#!/usr/bin/env python
# -*- coding: utf-8 -*-


"""
    OpenGEODE SDL92 parser

    This library builds the SDL AST (described in ogAST.py)
    The AST can then be used to build SDL backends such as the
    diagram editor (placing symbols in a graphical canvas for editition)
    or code generators, etc.

    The AST build is based on the ANTLR-grammar and generated lexer and parser
    (the grammar is in the file sdl92.g and requires antlr 3.1.3 for Python
    to be compiled and used).

    During the build of the AST this library makes a number of semantic
    checks on the SDL input mode.

    Copyright (c) 2012-2013 European Space Agency

    Designed and implemented by Maxime Perrotin

    Contact: maxime.perrotin@esa.int
"""

__author__ = 'Maxime Perrotin'

import sys
import os
import logging
import traceback
from itertools import chain, permutations, combinations
from collections import defaultdict
import antlr3
import antlr3.tree

import sdl92Lexer as lexer
from sdl92Parser import sdl92Parser

import samnmax
import ogAST
from Asn1scc import parse_asn1, ASN1

LOG = logging.getLogger(__name__)

EXPR_NODE = {
    lexer.PLUS: ogAST.ExprPlus,
    lexer.ASTERISK: ogAST.ExprMul,
    lexer.IMPLIES: ogAST.ExprImplies,
    lexer.DASH: ogAST.ExprMinus,
    lexer.OR: ogAST.ExprOr,
    lexer.AND: ogAST.ExprAnd,
    lexer.XOR: ogAST.ExprXor,
    lexer.EQ: ogAST.ExprEq,
    lexer.NEQ: ogAST.ExprNeq,
    lexer.GT: ogAST.ExprGt,
    lexer.GE: ogAST.ExprGe,
    lexer.LT: ogAST.ExprLt,
    lexer.LE: ogAST.ExprLe,
    lexer.DIV: ogAST.ExprDiv,
    lexer.MOD: ogAST.ExprMod,
    lexer.APPEND: ogAST.ExprAppend,
    lexer.IN: ogAST.ExprIn,
    lexer.REM: ogAST.ExprRem,
    lexer.NOT: ogAST.ExprNot,
    lexer.NEG: ogAST.ExprNeg,
    lexer.PRIMARY: ogAST.Primary,
}

# Insert current path in the search list for importing modules
sys.path.insert(0, '.')

DV = None

# Code generator backends may need some intemediate variables to process
# expressions. For convenience and to avoid multiple pass parsing, the parser
# tries to guess where they may be useful, and adds a hint in the AST.
TMPVAR = 0

# ASN.1 types used to support the signature of special operators
INTEGER = type('IntegerType', (object,), {'kind': 'IntegerType',
                                          'Min': str(-(2 ** 63)),
                                          'Max': str(2 ** 63 - 1)})
INT32 = type('Integer32Type', (object,), {'kind': 'Integer32Type',
                                          'Min': '-2147483648',
                                          'Max': '2147483647'})
NUMERICAL = type('NumericalType', (object,), {'kind': 'Numerical'})
TIMER = type('TimerType', (object,), {'kind': 'TimerType'})
REAL = type('RealType', (object,), {'kind': 'RealType',
                                    'Min': str(1e-308),
                                    'Max': str(1e308)})
LIST = type('ListType', (object,), {'kind': 'ListType'})
ANY_TYPE = type('AnyType', (object,), {'kind': 'AnyType'})
CHOICE = type('ChoiceType', (object,), {'kind': 'ChoiceType'})
BOOLEAN = type('BooleanType', (object,), {'kind': 'BooleanType'})
RAWSTRING = type('RawString', (object,), {'kind': 'StandardStringType'})
OCTETSTRING = type('OctetString', (object,), {'kind': 'OctetStringType'})
ENUMERATED = type('EnumeratedType', (object,), {'kind': 'EnumeratedType'})

UNKNOWN_TYPE = type('UnknownType', (object,), {'kind': 'UnknownType'})


# Special SDL operators and signature
SPECIAL_OPERATORS = {'length': [LIST],
                     'write': [ANY_TYPE],
                     'writeln': [ANY_TYPE],
                     'present': [CHOICE],
                     'set_timer': [INTEGER, TIMER],
                     'reset_timer': [TIMER],
                     'abs': [NUMERICAL],
                     'num': [ENUMERATED],
                     'float': [NUMERICAL],
                     'fix': [NUMERICAL],
                     'power': [NUMERICAL, INTEGER]}

# Container to keep a list of types mapped from ANTLR Tokens
# (Used with singledispatch/visitor pattern)
ANTLR_TOKEN_TYPES = {a: type(a, (antlr3.tree.CommonTree,), {})
                    for a, b in lexer.__dict__.viewitems() if type(b) == int}


# Shortcut to create a new referenced ASN.1 type
new_ref_type = lambda refname: \
        type(str(refname), (object,),
                {'kind': 'ReferenceType',
                 'ReferencedTypeName': refname.replace('_', '-')})

# Shortcut to return a type name (Reference name or basic type)
type_name = lambda t: \
                t.kind if t.kind != 'ReferenceType' else t.ReferencedTypeName

types = lambda: getattr(DV, 'types', {})


def is_integer(ty):
    ''' Return true if a type is an Integer Type '''
    return find_basic_type(ty).kind in (
        'IntegerType',
        'Integer32Type'
    )


def is_numeric(ty):
    ''' Return true if a type is a Numeric Type '''
    return find_basic_type(ty).kind in (
        'IntegerType',
        'Integer32Type',
        'Numerical',
        'RealType'
    )


def is_string(ty):
    ''' Return true if a type is a String Type '''
    return find_basic_type(ty).kind in (
        'StandardStringType',
        'OctetStringType'
    )


def sdl_to_asn1(sort):
    '''
        Convert case insensitive type reference to the actual type as found
        in the ASN.1 datamodel
    '''
    for asn1_type in types().viewkeys():
        if sort.replace('_', '-').lower() == asn1_type.lower():
            break
    else:
        raise TypeError('Type {} not found in ASN.1 model'.format(sort))
    return new_ref_type(asn1_type)


def node_filename(node):
    ''' Return the filename associated to the stream of this node '''
    parent = node
    while parent:
        try:
            return parent.getToken().getInputStream().fileName
        except AttributeError:
            parent = parent.getParent()
    return None


def token_stream(node):
    '''
        Return the token stream associated to a tree node
        It is set at the root of the tree by the parser
    '''
    parent = node
    while parent:
        try:
            return parent.token_stream
        except AttributeError:
            parent = parent.getParent()


def signals_in_system(ast):
    ''' Recursively find signal definitions in a nested SDL model '''
    all_signals = []
    for block in ast.blocks:
        all_signals.extend(signals_in_system(block))
    all_signals.extend(ast.signals)
    return all_signals


def find_process_declaration(ast, process_name):
    ''' Recursively search for a process declaration in a nested SDL model '''
    for block in ast.blocks:
        result = find_process_declaration(block, process_name)
        if result:
            return result
    try:
        for process in ast.processes:
            if process.processName == process_name:
                return process
    except AttributeError:
        return None
    return None


def valid_output(scope):
    '''
        Yields the output, procedures, and operators names,
        that is all the elements that can be valid in an OUTPUT symbol
        (does not mean it IS valid - caller still has to check it)
    '''
    for out_sig in scope.output_signals:
        yield out_sig['name'].lower()
    for proc in scope.procedures:
        yield proc.inputString.lower()
    for special_op in SPECIAL_OPERATORS:
        yield special_op.lower()


def get_interfaces(ast, process_name):
    '''
        Search for the list of input and output signals (async PI/RI)
        and procedures (sync RI) of a process in a given top-level AST
    '''
    all_signals = []
    async_signals = []
    system = None

    # Move up to the system level, in case process is nested in a block
    # and not defined at root level as it is the case when it is referenced
    system = ast
    while hasattr(system, 'parent'):
        system = system.parent

    # If we are at AST level, check in all systems, otherwise in current one
    iterator = ast.systems if hasattr(ast, 'systems') else (system,)

    for system in iterator:
        all_signals.extend(signals_in_system(system))
        process_ref = find_process_declaration(system, process_name)
        if process_ref:
            # Go to the block where the process is defined
            process_parent = process_ref.parent
            break
    else:
        if isinstance(ast, ogAST.Block):
            process_parent = ast
        else:
            raise TypeError('Process ' + process_name +
                        ' is defined but not not declared in a system')
    # Find in and out signals names using the signalroutes
    for signalroute in process_parent.signalroutes:
        for route in signalroute['routes']:
            if route['source'] == process_name:
                direction = 'out'
            elif route['dest'] == process_name:
                direction = 'in'
            else:
                continue
            for sig_id in route['signals']:
                # Copy the signal to the result dict
                found, = [dict(sig) for sig in all_signals
                          if sig['name'] == sig_id]
                found['direction'] = direction
                async_signals.append(found)
    return async_signals, system.procedures


def get_input_string(root):
    ''' Return the input string of a tree node '''
    return token_stream(root).toString(root.getTokenStartIndex(),
            root.getTokenStopIndex())


def error(root, msg):
    ''' Return an error message '''
    return '{} - "{}"'.format(msg, get_input_string(root))


def warning(root, msg):
    ''' Return a warning message '''
    return '{} - "{}"'.format(msg, get_input_string(root))


def tmp():
    ''' Return a temporary variable name '''
    global TMPVAR
    varname = TMPVAR
    TMPVAR += 1
    return varname


def get_state_list(process_root):
    ''' Return the list of states of a process '''
    # 1) get all STATE statements
    states = (child for child in process_root.getChildren()
            if child.type == lexer.STATE)
    # 2) keep only the ones containing a STATELIST token (i.e. no ASTERISK)
    relevant = (child for state in states for child in state.getChildren()
            if child.type == lexer.STATELIST)
    # 3) extract the state list from each of them
    state_list = [s.text.lower() for r in relevant for s in r.getChildren()]
    # state_list.append('START')
    # 4) create a set to remove duplicates
    return set(state_list)


def find_basic_type(a_type):
    ''' Return the ASN.1 basic type of a_type '''
    basic_type = a_type or UNKNOWN_TYPE
    while basic_type.kind == 'ReferenceType':
        # Find type with proper case in the data view
        for typename in types().viewkeys():
            if typename.lower() == basic_type.ReferencedTypeName.lower():
                basic_type = types()[typename].type
                break
        else:
            raise TypeError('Type "' + type_name(basic_type) +
                            '" was not found in Dataview')
    return basic_type


def is_constant(var):
    ''' Check in ASN.1 modules if var (Primary) is declared as a constant '''
    if var is None:
        return False
    if isinstance(var, ogAST.PrimConstant):
        return True
    if DV and isinstance(var, ogAST.PrimVariable):
        for mod in DV.asn1Modules:
            for constant in DV.exportedVariables[mod]:
                if(constant.lower() == var.value[0].lower().replace('_', '-')):
                    LOG.debug('Constant ' + var.inputString + ' found')
                    return True
    return False


def fix_special_operators(op_name, expr_list, context):
    ''' Verify/fix type of special operators parameters '''
    if op_name.lower() in ('length', 'present', 'abs', 'float', 'fix', 'num'):
        if len(expr_list) != 1:
            raise AttributeError('Only one parameter for the {} operator'
                                 .format(op_name))
        expr = expr_list[0]
        if expr.exprType is UNKNOWN_TYPE:
            expr.exprType = find_variable(expr.value[0], context)
            # XXX should change type to PrimVariable
        basic = find_basic_type(expr.exprType)
        if op_name.lower() == 'length' and basic.kind != 'SequenceOfType' \
                and not is_string(basic):
            raise TypeError('Length operator works only on strings/lists')
        elif op_name.lower() == 'present' and basic.kind != 'ChoiceType':
            raise TypeError('Present operator works only on CHOICE types')
        elif op_name.lower() in ('abs', 'float', 'fix') \
                and not is_numeric(basic):
            raise TypeError('"{}" operator needs a numerical parameter'.format(
                op_name))
        elif op_name.lower() == 'num' and basic.kind != 'EnumeratedType':
            raise TypeError('Num operaror works only with enumerations')
    elif op_name.lower() == 'power':
        if len(expr_list) != 2:
            raise AttributeError('The "power" operator takes two parameters')
        for idx, expr in enumerate(expr_list):
            if expr.exprType is UNKNOWN_TYPE:
                expr.exprType = find_variable(expr.value[0], context)
                # XXX should change type to PrimVariable
            if idx == 0 and not is_numeric(expr.exprType):
                raise TypeError('First parameter of power must be numerical')
            elif idx == 1 and not is_integer(expr.exprType):
                raise TypeError('Second parameter of power must be integer')
    elif op_name.lower() in ('write', 'writeln'):
        for param in expr_list:
            if param.exprType is UNKNOWN_TYPE:
                for each in (INTEGER, REAL, BOOLEAN, RAWSTRING, OCTETSTRING):
                    try:
                        check_type_compatibility(param, each, context)
                        param.exprType = each
                        break
                    except TypeError:
                        continue
                else:
                    # Type not found among supported types
                    # Has to be a variable...otherwise, error!
                    try:
                        param.exprType = find_variable(param.value[0], context)
                    except (KeyError, AttributeError):
                        raise TypeError('Could not determine type of argument'
                                        ' "{}"'.format(param.inputString))
            basic = find_basic_type(param.exprType)
            if basic.kind not in ('IntegerType', 'Integer32Type',
                                  'RealType', 'BooleanType') \
                                and not basic.kind.endswith('StringType'):
                # Currently supported printable types
                raise TypeError('Write operator does not support type')
    elif op_name.lower() == 'set_timer':
        if len(expr_list) != 2:
            raise TypeError('SET_TIMER has 2 parameters: (int, timer_name)')
        basic = find_basic_type(expr_list[0].exprType)
        if not basic.kind.startswith('Integer'):
            raise TypeError('SET_TIMER first parameter is not an integer')
        timer = expr_list[1].inputString
        for each in chain(context.timers, context.global_timers):
            if each.lower() == timer.lower():
                break
        else:
            raise TypeError('Timer {} is not defined'.format(timer))
    elif op_name.lower == 'reset_timer':
        if len(expr_list) != 1:
            raise TypeError('RESET_TIMER has 1 parameter: timer_name')
        timer = expr_list[0].inputString
        for each in context.timers:
            if each.lower() == timer.lower():
                break
        else:
            raise TypeError('Timer {} is not defined'.format(timer))
    else:
        # TODO: other operators
        return


def check_and_fix_op_params(op_name, expr_list, context):
    '''
        Verify and/or set the type of a procedure/output parameters
        TODO: when supported, add operators
    '''
    # (1) Find the signature of the function
    # signature will hold the list of parameters for the function
    LOG.debug('[check_and_fix_op_params] ' + op_name + ' - ' + str(expr_list))
    signature = []
    key = ''

    for out_sig in context.output_signals:
        if out_sig['name'].lower() == op_name.lower():
            if out_sig.get('type'):
                # output signals: one single parameter
                signature = [{'type': out_sig.get('type'),
                              'name': out_sig.get('param_name' or ''),
                              'direction': 'in'}]
            break
    else:
        # Procedures (inner and external)
        for inner_proc in context.procedures:
            key = inner_proc.inputString
            if key.lower() == op_name.lower():
                signature = inner_proc.fpar
                break
        else:
            if op_name.lower() not in SPECIAL_OPERATORS:
                raise AttributeError('Operator/output/procedure not found: '
                    + op_name)
            else:
                # Special operators: parameters are context dependent
                fix_special_operators(op_name, expr_list, context)
                return
    # (2) Check that the number of given parameters matches the signature
    if signature is not None and len(signature) != len(expr_list):
        raise TypeError('Wrong number of parameters')
    # (3) Check each individual parameter type
    for idx, param in enumerate(expr_list):
        if signature is None:
            break
        # Get parameter type name from the function signature:
        param_type = type_name(signature[idx].get('type'))
        # Retrieve the type (or None if it is a sepecial operator)
        dataview_entry = types().get(param_type) or UNKNOWN_TYPE
        if dataview_entry is not UNKNOWN_TYPE:
            dataview_type = new_ref_type(param_type)
        else:
            dataview_type = UNKNOWN_TYPE

        expr = ogAST.ExprAssign()
        expr.left = ogAST.PrimVariable()
        expr.left.exprType = dataview_type
        expr.right = param
        fix_expression_types(expr, context)
        expr_list[idx] = expr.right
        if signature[idx].get('direction') != 'in' \
                and not isinstance(expr.right, ogAST.PrimVariable):
            raise TypeError('OUT parameter "{}" is not a variable'
                            .format(expr.right.inputString))


def check_range(typeref, type_to_check):
    ''' Verify the that the Min/Max bounds of two types are compatible
        Called to test that assignments are withing allowed range
        both types assumed to be basic types
    '''
    try:
        if float(type_to_check.Min) < float(typeref.Min) \
                or float(type_to_check.Max) > float(typeref.Max):
            raise TypeError('Expression evaluation in range [{}..{}], '
                            'outside expected range [{}..{}]'
                    .format(type_to_check.Min, type_to_check.Max,
                            typeref.Min, typeref.Max))
    except (AttributeError, ValueError):
        raise TypeError('Missing range')


def check_type_compatibility(primary, typeRef, context):
    '''
        Check if an ogAST.Primary (raw value, enumerated, ASN.1 Value...)
        is compatible with a given type (typeRef is an ASN1Scc type)
        Does not return anything if OK, otherwise raises TypeError
    '''
    assert typeRef is not None
    if typeRef is UNKNOWN_TYPE:
        raise TypeError('Type reference is unknown')
    if isinstance(primary, ogAST.PrimConstant):
        # ASN.1 constants type is unknown (Asn1 backend to be completed)
        return
    actual_type = find_basic_type(typeRef)
    LOG.debug("[check_type_compatibility] "
              "checking if {value} is of type {typeref}"
              .format(value=primary.inputString, typeref=type_name(typeRef)))

    if (isinstance(primary, ogAST.PrimEnumeratedValue)
            and actual_type.kind.endswith('EnumeratedType')):
        # If type ref is an enumeration, check that the value is valid
        # Note, when using the "present" operator of a CHOICE type, the
        # resulting value is actually an EnumeratedType
        enumerant = primary.inputString.replace('_', '-')
        corr_type = actual_type.EnumValues.get(enumerant)
        if corr_type:
            return
        else:
            err = ('Value "' + primary.inputString +
                   '" not in this enumeration: ' +
                   str(actual_type.EnumValues.keys()))
            raise TypeError(err)
    elif isinstance(primary, ogAST.PrimConditional):
        then_expr = primary.value['then']
        else_expr = primary.value['else']

        for expr in (then_expr, else_expr):
            if expr.is_raw:
                check_type_compatibility(expr, typeRef, context)
        return

    elif isinstance(primary, ogAST.PrimVariable):
        try:
            compare_types(primary.exprType, typeRef)
        except TypeError as err:
            raise TypeError('{expr} should be of type {ty} - {err}'
                            .format(expr=primary.inputString,
                                    ty=type_name(typeRef),
                                    err=str(err)))
        return
    elif isinstance(primary, ogAST.PrimInteger) \
            and actual_type.kind.startswith('Integer'):
        return

    elif isinstance(primary, ogAST.PrimReal) \
            and actual_type.kind.startswith('Real'):
        return

    elif isinstance(primary, ogAST.PrimBoolean) \
            and actual_type.kind.startswith('Boolean'):
        return
    elif (isinstance(primary, ogAST.PrimEmptyString) and
                                         actual_type.kind == 'SequenceOfType'):
        if int(actual_type.Min) == 0:
            return
        else:
            raise TypeError('SEQUENCE OF has a minimum size of '
                            + actual_type.Min + ')')
    elif isinstance(primary, ogAST.PrimSequenceOf) \
            and actual_type.kind == 'SequenceOfType':
        if (len(primary.value) < int(actual_type.Min) or
                len(primary.value) > int(actual_type.Max)):
            raise TypeError(str(len(primary.value)) +
                      ' elements in SEQUENCE OF, while constraint is [' +
                      str(actual_type.Min) + '..' + str(actual_type.Max) + ']')
        for elem in primary.value:
            check_type_compatibility(elem, actual_type.type, context)
        return
    elif isinstance(primary, ogAST.PrimSequence) \
            and actual_type.kind == 'SequenceType':
        user_nb_elem = len(primary.value.keys())
        type_nb_elem = len(actual_type.Children.keys())
        if user_nb_elem != type_nb_elem:
            raise TypeError('Wrong number of fields in SEQUENCE of type {}'
                            .format(type_name(typeRef)))
        else:
            for field, fd_data in actual_type.Children.viewitems():
                ufield = field.replace('-', '_')
                if ufield not in primary.value:
                    raise TypeError('Missing field {field} in SEQUENCE'
                                    ' of type {t1} '
                                    .format(field=ufield,
                                            t1=type_name(typeRef)))
                else:
                    # If the user field is a raw value
                    if primary.value[ufield].is_raw:
                        check_type_compatibility(primary.value[ufield],
                                                 fd_data.type, context)
                    else:
                        # Compare the types for semantic equivalence
                        try:
                            compare_types(
                                primary.value[ufield].exprType, fd_data.type)
                        except TypeError as err:
                            raise TypeError('Field ' + ufield +
                                        ' is not of the proper type, i.e. ' +
                                        type_name(fd_data.type) +
                                        ' - ' + str(err))
        return
    elif isinstance(primary, ogAST.PrimChoiceItem) \
                              and actual_type.kind.startswith('Choice'):
        for choicekey, choice in actual_type.Children.viewitems():
            if choicekey.lower() == primary.value['choice'].lower():
                break
        else:
            raise TypeError('Non-existent choice "{choice}" in type {t1}'
                            .format(choice=primary.value['choice'],
                            t1=type_name(typeRef)))
        # compare primary.value['value']
        # with actual_type['Children'][primary.choiceItem['choice']]
        value = primary.value['value']
        choice_field_type = choice.type
        # if the user field is a raw value:
        if value.is_raw:
            check_type_compatibility(value, choice_field_type, context)
        # Compare the types for semantic equivalence:
        else:
            try:
                compare_types(value.exprType, choice_field_type)
            except TypeError as err:
                raise TypeError(
                            'Field {field} in CHOICE is not of type {t1} - {e}'
                            .format(field=primary.value['choice'],
                                    t1=type_name(choice_field_type),
                                    e=str(err)))
        value.exprType = choice_field_type         # XXX
        return
    elif isinstance(primary, ogAST.PrimChoiceDeterminant) \
                and actual_type.kind.startswith('Choice'):
        for choicekey, choice in actual_type.EnumValues.viewitems():
            if choicekey.replace('-', '_').lower() == \
                    primary.inputString.lower():
                break
        else:
            raise TypeError('Non-existent choice "{choice}" in type {t1}'
                            .format(choice=primary.inputString,
                            t1=type_name(typeRef)))

    elif isinstance(primary, ogAST.PrimStringLiteral):
        # Octet strings
        basic_type = find_basic_type(typeRef)
        if basic_type.kind == 'StandardStringType':
            return
        elif basic_type.kind.endswith('StringType'):
            if int(basic_type.Min) <= len(
                    primary.value[1:-1]) <= int(basic_type.Max):
                return
            else:
                raise TypeError('Invalid string literal - check that length is'
                                'within the bound limits {Min}..{Max}'.format
                            (Min=str(basic_type.Min), Max=str(basic_type.Max)))
        else:
            raise TypeError('String literal not expected')
    elif (isinstance(primary, ogAST.PrimMantissaBaseExp) and
                                            actual_type.kind == 'RealType'):
        LOG.debug('PROBABLY (it is a float but I did not check'
                  'if values are compatible)')
        return
    else:
        raise TypeError('{prim} does not match type {t1}'
                        .format(prim=primary.inputString,
                                t1=type_name(typeRef)))


def compare_types(type_a, type_b):
    '''
       Compare two types, return if they are semantically equivalent,
       otherwise raise TypeError
    '''
    LOG.debug('[compare_types]' + str(type_a) + ' and ' + str(type_b) + ': ')

    type_a = find_basic_type(type_a)
    type_b = find_basic_type(type_b)

    if type_a == type_b:
        return

    # Check if both types have basic compatibility

    simple_types = (
        'IntegerType',
        'BooleanType',
        'RealType',
        'StringType',
        'SequenceOfType',
        'Integer32Type',
        'OctetStringType'
    )

    for ty in (type_a, type_b):
        if ty.kind not in simple_types:
            raise TypeError('Type {} is not a basic type'.format(type_name(ty)))

    if type_a.kind == type_b.kind:
        if type_a.kind == 'SequenceOfType':
            if type_a.Min == type_b.Min and type_a.Max == type_b.Max:
                compare_types(type_a.type, type_b.type)
                return
            else:
                raise TypeError('Incompatible arrays')
        # TODO: Check that OctetString types have compatible range
        return
    elif is_string(type_a) and is_string(type_b):
        return
    elif is_integer(type_a) and is_integer(type_b):
        return
    else:
        raise TypeError('Incompatible types {} and {}'.format(
            type_name(type_a),
            type_name(type_b)
        ))


def find_variable(var, context):
    ''' Look for a variable name in the context and return its type '''
    result = UNKNOWN_TYPE
    LOG.debug('[find_variable] checking if ' + str(var) + ' is defined')
    # all DCL-variables
    all_visible_variables = dict(context.global_variables)
    all_visible_variables.update(context.variables)
    # First check locally, i.e. in FPAR
    try:
        for variable in context.fpar:
            if variable['name'].lower() == var.lower():
                LOG.debug(str(var) + ' is defined')
                return variable['type']
    except AttributeError:
        # No FPAR section
        pass
    for varname, (vartype, _) in all_visible_variables.viewitems():
        # Case insensitive comparison with variables
        if var.lower() == varname.lower():
            result = vartype
            LOG.debug(str(var) + ' is defined')
            return result
    for timer in chain(context.timers, context.global_timers):
        if var.lower() == timer.lower():
            LOG.debug(str(var) + ' is defined')
            return result

    LOG.debug('[find_variable] result: not found, raising exception')
    raise AttributeError('Variable {var} not defined'.format(var=var))


def fix_enumerated_and_choice(expr_enum, context):
    ''' If left side of the expression is of Enumerated or Choice type,
        check if right side is a literal of that sort, and update type '''
    kind = find_basic_type(expr_enum.left.exprType).kind
    if kind == 'EnumeratedType':
        prim = ogAST.PrimEnumeratedValue(primary=expr_enum.right)
    elif kind == 'ChoiceEnumeratedType':
        prim = ogAST.PrimChoiceDeterminant(primary=expr_enum.right)
    try:
        check_type_compatibility(prim, expr_enum.left.exprType, context)
        expr_enum.right = prim
        expr_enum.right.exprType = expr_enum.left.exprType
    except (UnboundLocalError, AttributeError, TypeError):
        pass
    else:
        LOG.debug('Fixed enumerated/choice: {}'.format(expr_enum.inputString))


def fix_expression_types(expr, context):
    ''' Check/ensure type consistency in binary expressions '''
    for _ in range(2):
        # Check if an raw enumerated value is of a reference type
        fix_enumerated_and_choice(expr, context)
        expr.right, expr.left = expr.left, expr.right

#   for side in permutations(('left', 'right')):
#       side_type = find_basic_type(getattr(expr, side[0]).exprType).kind
#       if side_type == 'EnumeratedType':
#           prim = ogAST.PrimEnumeratedValue(primary=getattr(expr, side[1]))
#       elif side_type == 'ChoiceEnumeratedType':
#           prim = ogAST.PrimChoiceDeterminant(primary=getattr(expr, side[1]))
#       try:
#           check_type_compatibility(prim, getattr(expr, side[0]).exprType,
#                                    context)
#           setattr(expr, side[1], prim)
#           getattr(expr, side[1]).exprType = getattr(expr, side[0]).exprType
#       except (UnboundLocalError, AttributeError, TypeError):
#           pass

    # If a side type remains unknown, check if it is an ASN.1 constant
    for side in permutations(('left', 'right')):
        value = getattr(expr, side[0])
        if value.exprType == UNKNOWN_TYPE and is_constant(value):
            setattr(expr, side[0], ogAST.PrimConstant(primary=value))
            getattr(expr, side[0]).exprType = getattr(expr, side[1]).exprType

    for side in (expr.right, expr.left):
        if side.is_raw:
            raw_expr = side
        else:
            typed_expr = side
            ref_type = typed_expr.exprType

    # If a side is a raw Sequence Of with unknown type, try to resolve it
    for side in permutations(('left', 'right')):
        value = getattr(expr, side[0])  # get expr.left then expr.right
        if not isinstance(value, ogAST.PrimSequenceOf):
            continue
        other = getattr(expr, side[1])  # other side
        basic = find_basic_type(value.exprType)
        if basic.kind == 'SequenceOfType' and basic.type == UNKNOWN_TYPE:
            asn_type = find_basic_type(other.exprType)
            if asn_type.kind == 'SequenceOfType':
                asn_type = asn_type.type
                for idx, elem in enumerate(value.value):
                    check_expr = ogAST.ExprAssign()
                    check_expr.left = ogAST.PrimVariable()
                    check_expr.left.exprType = asn_type
                    check_expr.right = elem
                    fix_expression_types(check_expr, context)
                    value.value[idx] = check_expr.right
            # the type of the raw PrimSequenceOf can be set now
            value.exprType.type = asn_type

    if isinstance(expr, ogAST.ExprIn):
        return

    if not expr.right.is_raw and not expr.left.is_raw:
        unknown = [uk_expr for uk_expr in expr.right, expr.left
                   if uk_expr.exprType == UNKNOWN_TYPE]
        if unknown:
            #print traceback.print_stack()
            raise TypeError('Cannot resolve type of "{}"'
                            .format(unknown[0].inputString))

    # In Sequence, Choice and SEQUENCE OF expressions,
    # we must fix missing inner types
    # (due to similarities, the following should be refactored FIXME)
    if isinstance(expr.right, ogAST.PrimSequence):
        # left side must have a known type
        asn_type = find_basic_type(expr.left.exprType)
        if asn_type.kind != 'SequenceType':
            raise TypeError('left side must be a SEQUENCE type')
        for field, fd_expr in expr.right.value.viewitems():
            if fd_expr.exprType == UNKNOWN_TYPE:
                try:
                    expected_type = asn_type.Children.get(
                            field.replace('_', '-')).type
                except AttributeError:
                    raise TypeError('Field not found: ' + field)
                check_expr = ogAST.ExprAssign()
                check_expr.left = ogAST.PrimVariable()
                check_expr.left.exprType = expected_type
                check_expr.right = fd_expr
                fix_expression_types(check_expr, context)
                # Id of fd_expr may have changed (enumerated, choice)
                expr.right.value[field] = check_expr.right
    elif isinstance(expr.right, ogAST.PrimChoiceItem):
        asn_type = find_basic_type(expr.left.exprType)
        field = expr.right.value['choice'].replace('_', '-')
        if asn_type.kind != 'ChoiceType' \
                or field.lower() not in [key.lower()
                                  for key in asn_type.Children.viewkeys()]:
            raise TypeError('Field is not valid in CHOICE:' + field)
        key, = [key for key in asn_type.Children.viewkeys()
                if key.lower() == field.lower()]
        if expr.right.value['value'].exprType == UNKNOWN_TYPE:
            try:
                expected_type = asn_type.Children.get(key).type
            except AttributeError:
                raise TypeError('Field not found in CHOICE: ' + field)
            check_expr = ogAST.ExprAssign()
            check_expr.left = ogAST.PrimVariable()
            check_expr.left.exprType = expected_type
            check_expr.right = expr.right.value['value']
            fix_expression_types(check_expr, context)
            expr.right.value['value'] = check_expr.right
    elif isinstance(expr.right, ogAST.PrimConditional):
        for det in ('then', 'else'):
            # Recursively fix possibly missing types in the expression
            check_expr = ogAST.ExprAssign()
            check_expr.left = ogAST.PrimVariable()
            check_expr.left.exprType = expr.left.exprType
            check_expr.right = expr.right.value[det]
            fix_expression_types(check_expr, context)
            expr.right.value[det] = check_expr.right

    if expr.right.is_raw != expr.left.is_raw:
        check_type_compatibility(raw_expr, ref_type, context)
        if not raw_expr.exprType.kind.startswith(('Integer', 'Real')):
            # Raw int/real must keep their type because of the range
            # that can be computed
            raw_expr.exprType = ref_type
    else:
        compare_types(expr.left.exprType, expr.right.exprType)


def expression_list(root, context):
    ''' Parse a list of expression parameters '''
    errors = []
    warnings = []
    result = []
    for param in root.getChildren():
        exp, err, warn = expression(param, context)
        errors.extend(err)
        warnings.extend(warn)
        result.append(exp)
    return result, errors, warnings


def primary_variable(root, context):
    ''' Primary Variable analysis '''
    lexeme = root.children[0].text

    # Differentiate DCL and FPAR variables
    Prim = ogAST.PrimVariable
    if isinstance(context, ogAST.Procedure):
        for each in context.fpar:
            if each['name'].lower() == lexeme.lower():
                Prim = ogAST.PrimFPAR
                break

    prim, errors, warnings = Prim(), [], []
    prim.value = [root.children[0].text]
    prim.exprType = UNKNOWN_TYPE
    prim.inputString = get_input_string(root)
    prim.tmpVar = tmp()

    try:
        prim.exprType = find_variable(lexeme, context)
    except AttributeError:
        pass

    return prim, errors, warnings


def binary_expression(root, context):
    ''' Binary expression analysis '''
    errors, warnings = [], []

    ExprNode = EXPR_NODE[root.type]
    expr = ExprNode(
        get_input_string(root),
        root.getLine(),
        root.getCharPositionInLine()
    )
    expr.exprType = UNKNOWN_TYPE
    expr.tmpVar = tmp()

    left, right = root.children
    expr.left, err_left, warn_left = expression(left, context)
    expr.right, err_right, warn_right = expression(right, context)
    errors.extend(err_left)
    warnings.extend(warn_left)
    errors.extend(err_right)
    warnings.extend(warn_right)

    try:
        fix_expression_types(expr, context)
    except (AttributeError, TypeError) as err:
        errors.append(error(root, str(err)))

    return expr, errors, warnings


def unary_expression(root, context):
    ''' Unary expression analysys '''
    ExprNode = EXPR_NODE[root.type]
    expr = ExprNode(
        get_input_string(root),
        root.getLine(),
        root.getCharPositionInLine()
    )
    expr.exprType = UNKNOWN_TYPE
    expr.tmpVar = tmp()

    expr.expr, errors, warnings = expression(root.children[0], context)

    return expr, errors, warnings


def expression(root, context):
    ''' Expression analysis (e.g. 5+5*hello(world)!foo) '''
    logic = (lexer.OR, lexer.AND, lexer.XOR)
    arithmetic = (lexer.PLUS, lexer.ASTERISK, lexer.DASH,
                  lexer.DIV, lexer.MOD, lexer.REM)
    relational = (lexer.EQ, lexer.NEQ, lexer.GT, lexer.GE, lexer.LT, lexer.LE)

    if root.type in logic:
        return logic_expression(root, context)
    elif root.type in arithmetic:
        return arithmetic_expression(root, context)
    elif root.type in relational:
        return relational_expression(root, context)
    elif root.type == lexer.IN:
        return in_expression(root, context)
    elif root.type == lexer.APPEND:
        return append_expression(root, context)
    elif root.type == lexer.NOT:
        return not_expression(root, context)
    elif root.type == lexer.NEG:
        return neg_expression(root, context)
    elif root.type == lexer.PAREN:
        return expression(root.children[0], context)
    elif root.type == lexer.CONDITIONAL:
        return conditional_expression(root, context)
    elif root.type == lexer.PRIMARY:
        return primary(root.children[0], context)
    elif root.type == lexer.CALL:
        return call_expression(root, context)
    elif root.type == lexer.SELECTOR:
        return selector_expression(root, context)
    else:
        raise NotImplementedError


def logic_expression(root, context):
    ''' Logic expression analysis '''
    shortcircuit = ''
    # detect optional THEN in AND/OR expressions, indicating that the
    # short-circuit version of the operator is needed, to prevent the
    # evaluation of the right part if the left part does not evaluate
    # to true.
    if root.type in (lexer.OR, lexer.AND) and len(root.children) == 3:
        if root.children[1].type in (lexer.THEN, lexer.ELSE):
            root.children.pop(1)
            shortcircuit = ' else' if root.type == lexer.OR else ' then'

    expr, errors, warnings = binary_expression(root, context)
    expr.shortcircuit = shortcircuit

    left_bty = find_basic_type(expr.left.exprType)
    right_bty = find_basic_type(expr.right.exprType)

    for bty in left_bty, right_bty:
        if shortcircuit and bty.kind != 'BooleanType':
            msg = 'Shortcircuit operators only work with type Boolean'
            errors.append(error(root, msg))
            break

        if bty.kind == 'BooleanType':
            continue
        elif bty.kind == 'BitStringType' and bty.Min == bty.Max:
            continue
        elif bty.kind == 'SequenceOfType' and bty.Min == bty.Max \
                and find_basic_type(bty.type).kind == 'BooleanType':
            continue
        else:
            msg = 'Bitwise operators only work with Booleans, ' \
                  'fixed size SequenceOf Booleans or fixed size BitStrings'
            errors.append(error(root, msg))
            break

    if left_bty.kind == right_bty.kind == 'BooleanType':
        expr.exprType = BOOLEAN
    else:
        expr.exprType = expr.left.exprType

    return expr, errors, warnings


def arithmetic_expression(root, context):
    ''' Arithmetic expression analysis '''
    expr, errors, warnings = binary_expression(root, context)

    # Expressions returning a numerical type must have their range defined
    # accordingly with the kind of opration used between operand:
    basic = find_basic_type(expr.left.exprType)
    left = find_basic_type(expr.left.exprType)
    right = find_basic_type(expr.right.exprType)
    try:
        if isinstance(expr, ogAST.ExprPlus):
            attrs = {'Min': str(float(left.Min) + float(right.Min)),
                     'Max': str(float(left.Max) + float(right.Max))}
            expr.exprType = type('Plus', (basic,), attrs)
        elif isinstance(expr, ogAST.ExprMul):
            attrs = {'Min': str(float(left.Min) * float(right.Min)),
                     'Max': str(float(left.Max) * float(right.Max))}
            expr.exprType = type('Mul', (basic,), attrs)
        elif isinstance(expr, ogAST.ExprMinus):
            attrs = {'Min': str(float(left.Min) - float(right.Min)),
                     'Max': str(float(left.Max) - float(right.Max))}
            expr.exprType = type('Minus', (basic,), attrs)
        elif isinstance(expr, ogAST.ExprDiv):
            attrs = {'Min': str(float(left.Min) / (float(right.Min) or 1)),
                     'Max': str(float(left.Max) / (float(right.Max) or 1))}
            expr.exprType = type('Div', (basic,), attrs)
        elif isinstance(expr, (ogAST.ExprMod, ogAST.ExprRem)):
            attrs = {'Min': right.Min, 'Max': right.Max}
            expr.exprType = type('Mod', (basic,), attrs)
    except (ValueError, AttributeError):
        msg = 'Check that all your numerical data types '\
              'have a range constraint'
        errors.append(error(root, msg))

    if root.type in (lexer.REM, lexer.MOD):
        for ty in (expr.left.exprType, expr.right.exprType):
            if not is_integer(ty):
                msg = 'Mod/Rem expressions can only applied to Integer types'
                errors.append(error(root, msg))
                break

    return expr, errors, warnings


def relational_expression(root, context):
    ''' Relational expression analysys '''
    expr, errors, warnings = binary_expression(root, context)

    if root.type not in (lexer.EQ, lexer.NEQ):
        for ty in (expr.left.exprType, expr.right.exprType):
            if not is_numeric(ty):
                errors.append(error(root,
                    'Operands in relational expressions must be numerical'))
                break

    expr.exprType = BOOLEAN

    return expr, errors, warnings


def in_expression(root, context):
    ''' In expression analysis '''
    # Left and right are reversed for IN operator
    root.children[0], root.children[1] = root.children[1], root.children[0]

    expr, errors, warnings = binary_expression(root, context)
    expr.exprType = BOOLEAN

    # check that left part is a SEQUENCE OF or a string
    left_type = expr.left.exprType
    container_basic_type = find_basic_type(expr.left.exprType)
    if container_basic_type.kind == 'SequenceOfType':
        ref_type = container_basic_type.type
    elif container_basic_type.kind.endswith('StringType'):
        ref_type = container_basic_type
    else:
        msg = 'IN expression: right part must be a list'
        errors.append(error(root, msg))
        return expr, errors, warnings
    expr.left.exprType = ref_type

    if find_basic_type(ref_type).kind == 'EnumeratedType':
        fix_enumerated_and_choice(expr, context)

    expr.left.exprType = left_type

    try:
        compare_types(expr.right.exprType, ref_type)
    except TypeError as err:
        errors.append(error(root, str(err)))

    if expr.right.is_raw and expr.left.is_raw:
        # If both sides are raw (e.g. "3 in {1,2,3}"), evaluate expression
        bool_expr = ogAST.PrimBoolean()
        bool_expr.inputString = expr.inputString
        bool_expr.line = expr.line
        bool_expr.charPositionInLine = expr.charPositionInLine
        bool_expr.exprType = type('PrBool', (object,), {'kind': 'BooleanType'})
        if expr.right.value in [each.value for each in expr.left.value]:
            bool_expr.value = ['true']
            warnings.append('Expression {} is always true'
                            .format(expr.inputString))
        else:
            bool_expr.value = ['false']
            warnings.append('Expression {} is always false'
                            .format(expr.inputString))
        expr = bool_expr

    return expr, errors, warnings


def append_expression(root, context):
    ''' Append expression analysis '''
    expr, errors, warnings = binary_expression(root, context)

    for bty in (find_basic_type(expr.left.exprType),
                find_basic_type(expr.right.exprType)):
        if bty.kind != 'SequenceOfType' and not is_string(bty):
            msg = 'Append can only be applied to types SequenceOf or String'
            errors.append(error(root, msg))
            break

    expr.exprType = expr.left.exprType
    return expr, errors, warnings


def not_expression(root, context):
    ''' Not expression analysis '''
    expr, errors, warnings = unary_expression(root, context)

    bty = find_basic_type(expr.expr.exprType)
    if bty.kind in ('BooleanType', ):
        expr.exprType = BOOLEAN
    elif bty.kind == 'BitStringType':
        expr.exprType = expr.expr.exprType
    elif bty.kind == 'SequenceOfType' and bty.type.kind == 'BooleanType':
        expr.exprType = expr.expr.exprType
    else:
        msg = 'Bitwise operators only work with booleans '\
              'and arrays of booleans'
        errors.append(error(root, msg))

    return expr, errors, warnings


def neg_expression(root, context):
    ''' Negative expression analysis '''
    expr, errors, warnings = unary_expression(root, context)

    basic = find_basic_type(expr.expr.exprType)
    if not is_numeric(basic):
        msg = 'Negative expressions can only be applied to numeric types'
        errors.append(error(root, msg))
        return expr, errors, warnings

    try:
        attrs = {'Min': str(-float(basic.Max)), 'Max': str(-float(basic.Min))}
        expr.exprType = type('Neg', (basic,), attrs)
    except (ValueError, AttributeError):
        msg = 'Check that all your numerical data types '\
              'have a range constraint'
        errors.append(error(root, msg))

    return expr, errors, warnings


def conditional_expression(root, context):
    ''' Conditional expression analysis '''
    errors, warnings = [], []

    expr = ogAST.PrimConditional(
        get_input_string(root),
        root.getLine(),
        root.getCharPositionInLine()
    )
    expr.exprType = UNKNOWN_TYPE
    expr.tmpVar = tmp()

    if_part, then_part, else_part = root.getChildren()

    if_expr, err, warn = expression(if_part, context)
    errors.extend(err)
    warnings.extend(warn)

    then_expr, err, warn = expression(then_part, context)
    errors.extend(err)
    warnings.extend(warn)

    else_expr, err, warn = expression(else_part, context)
    errors.extend(err)
    warnings.extend(warn)

    if find_basic_type(if_expr.exprType).kind != 'BooleanType':
        msg = 'Conditions in conditional expressions must be of type Boolean'
        errors.append(error(root, msg))

    # TODO: Refactor this
    try:
        expr.left = then_expr
        expr.right = else_expr
        fix_expression_types(expr, context)
        expr.exprType = then_expr.exprType
    except (AttributeError, TypeError) as err:
        if UNKNOWN_TYPE not in (then_expr.exprType, else_expr.exprType):
            errors.append(error(root, str(err)))

    expr.value = {
        'if': if_expr,
        'then': then_expr,
        'else': else_expr,
        'tmpVar': expr.tmpVar
    }

    return expr, errors, warnings


def call_expression(root, context):
    ''' Call expression analysis '''
    errors, warnings = [], []

    if root.children[0].type == lexer.PRIMARY:
        primary = root.children[0]
        if primary.children[0].type == lexer.VARIABLE:
            variable = primary.children[0]
            ident = variable.children[0].text.lower()
            proc_list = [proc.inputString.lower()
                         for proc in context.procedures]
            if ident in (SPECIAL_OPERATORS.keys() + proc_list):
                return primary_call(root, context)

    num_params = len(root.children[1].children)

    if num_params == 1:
        return primary_index(root, context)

    elif num_params == 2:
        return primary_substring(root, context)

    else:
        node = ogAST.PrimCall()  # Use error node instead?
        node.inputString = get_input_string(root)
        node.exprType = UNKNOWN_TYPE
        errors.append(error(root, 'Wrong number of parameters'))
        return node, errors, warnings


def primary_call(root, context):
    ''' Primary call analysis '''
    node, errors, warnings = ogAST.PrimCall(), [], []

    node.exprType = UNKNOWN_TYPE
    node.inputString = get_input_string(root)
    node.tmpVar = tmp()

    ident = root.children[0].children[0].children[0].text.lower()

    params, params_errors, param_warnings = \
                                expression_list(root.children[1], context)
    errors.extend(params_errors)
    warnings.extend(param_warnings)

    try:
        fix_special_operators(ident, params, context)
    except (AttributeError, TypeError) as err:
        errors.append(error(root, str(err)))

    node.value = [ident, {'procParams': params}]

    params_bty = [find_basic_type(p.exprType) for p in params]

    if ident == 'present':
        try:
            node.exprType = type('present', (object,), {
                'kind': 'ChoiceEnumeratedType',
                'EnumValues': params_bty[0].Children
            })
        except AttributeError:
            errors.append(error(root, 'Parameter type is not a CHOICE'))

    elif ident in ('length', 'fix'):
        # result is an integer type with range of the param type
        try:
            node.exprType = type('fix', (INTEGER,), {
                'Min': params_bty[0].Min,
                'Max': params_bty[0].Max
            })
        except AttributeError:
            errors.append(error(root, 'Parameter type has no range'))

    elif ident == 'float':
        try:
            node.exprType = type('float_op', (REAL,), {
                'Min': params_bty[0].Min,
                'Max': params_bty[0].Max
            })
        except AttributeError:
            errors.append(error(root, 'Parameter type has no range'))

    elif ident == 'power':
        try:
            node.exprType = type('Power', (params_bty[0],), {
                'Min': str(pow(float(params_bty[0].Min),
                               float(params_bty[1].Min))),
                'Max': str(pow(float(params_bty[0].Max),
                               float(params_bty[1].Max)))
            })
        except OverflowError:
            errors.append(error(root, 'Result can exceeds 64-bits'))
        except AttributeError:
            errors.append(error(root, 'Parameter type has no range'))

    elif ident == 'abs':
        try:
            node.exprType = type('Abs', (params_bty[0],), {
                'Min': str(max(float(params_bty[0].Min), 0)),
                'Max': str(max(float(params_bty[0].Max), 0))
            })
        except AttributeError:
            errors.append(error(root, '"Abs" parameter type has no range'))
    elif ident == 'num':
        try:
            enum_values = [int(each.IntValue)
                           for each in params_bty[0].EnumValues.viewvalues()]

            node.exprType = type('Num', (INTEGER,), {
                'Min': str(min(enum_values)),
                'Max': str(max(enum_values))
            })
        except AttributeError:
            errors.append(error(root, '"Num" parameter error'))

    return node, errors, warnings


def primary_index(root, context):
    ''' Primary index analysis '''
    node, errors, warnings = ogAST.PrimIndex(), [], []

    node.exprType = UNKNOWN_TYPE
    node.inputString = get_input_string(root)
    node.tmpVar = tmp()

    receiver, receiver_err, receiver_warn = \
                                expression(root.children[0], context)
    receiver_bty = find_basic_type(receiver.exprType)
    errors.extend(receiver_err)
    warnings.extend(receiver_warn)

    params, params_errors, param_warnings = \
                                expression_list(root.children[1], context)
    errors.extend(params_errors)
    warnings.extend(param_warnings)

    node.value = [receiver, {'index': params}]

    if receiver_bty.kind == 'SequenceOfType':
        node.exprType = receiver_bty.type
    else:
        msg = 'Index can only be applied to type SequenceOf'
        errors.append(error(root, msg))

    return node, errors, warnings


def primary_substring(root, context):
    ''' Primary substring analysis '''
    node, errors, warnings = ogAST.PrimSubstring(), [], []

    node.exprType = UNKNOWN_TYPE
    node.inputString = get_input_string(root)
    node.tmpVar = tmp()

    receiver, receiver_err, receiver_warn = \
                                    expression(root.children[0], context)
    receiver_bty = find_basic_type(receiver.exprType)
    errors.extend(receiver_err)
    warnings.extend(receiver_warn)

    params, params_errors, param_warnings = \
                                    expression_list(root.children[1], context)
    errors.extend(params_errors)
    warnings.extend(param_warnings)

    node.value = [receiver, {'substring': params, 'tmpVar': tmp()}]

    if receiver_bty.kind == 'SequenceOfType' or \
            receiver_bty.kind.endswith('StringType'):
        node.exprType = receiver.exprType
        # Check bounds
        basic = find_basic_type(node.exprType)
        min0 = find_basic_type(params[0].exprType).Min
        min1 = find_basic_type(params[1].exprType).Min
        max0 = find_basic_type(params[0].exprType).Max
        max1 = find_basic_type(params[1].exprType).Max
        if int(min0) > int(min1) or int(max0) > int(max1):
            msg = 'Substring bounds are invalid'
            errors.append(error(root, msg))
        if int(min0) > int(basic.Max) \
                or int(max1) > int(basic.Max):
            msg = 'Substring bounds [{}..{}] outside range [{}..{}]'.format(
                    min0, max1, basic.Min, basic.Max)
            errors.append(error(root, msg))
    else:
        msg = 'Substring can only be applied to types SequenceOf or String'
        errors.append(error(root, msg))

    return node, errors, warnings


def selector_expression(root, context):
    ''' Selector expression analysis '''
    errors, warnings = [], []

    node = ogAST.PrimSelector()
    node.exprType = UNKNOWN_TYPE
    node.inputString = get_input_string(root)
    node.tmpVar = tmp()

    receiver, receiver_err, receiver_warn = \
                                expression(root.children[0], context)
    receiver_bty = find_basic_type(receiver.exprType)
    errors.extend(receiver_err)
    warnings.extend(receiver_warn)

    field_name = root.children[1].text.replace('_', '-').lower()

    for n, f in receiver_bty.Children.viewitems():
        if n.lower() == field_name:
            node.exprType = f.type
            break
    else:
        msg = 'Field "{}" not found in expression {}'.format(field_name)
        errors.append(error(root, msg))

    node.value = [receiver, field_name.replace('-', '_').lower()]

    return node, errors, warnings


def primary(root, context):
    ''' Literal expression analysis '''
    prim, errors, warnings = None, [], []

    if root.type == lexer.VARIABLE:
        return primary_variable(root, context)
    elif root.type == lexer.INT:
        prim = ogAST.PrimInteger()
        prim.value = [root.text.lower()]
        prim.exprType = type('PrInt', (object,), {
            'kind': 'IntegerType',
            'Min': root.text,
            'Max': root.text
        })
    elif root.type in (lexer.TRUE, lexer.FALSE):
        prim = ogAST.PrimBoolean()
        prim.value = [root.text.lower()]
        prim.exprType = type('PrBool', (object,), {'kind': 'BooleanType'})
    elif root.type == lexer.FLOAT:
        prim = ogAST.PrimReal()
        prim.value = [root.text]
        prim.exprType = type('PrReal', (object,), {
            'kind': 'RealType',
            'Min': prim.value[0],
            'Max': prim.value[0]
        })
    elif root.type == lexer.STRING:
        prim = ogAST.PrimStringLiteral()
        prim.value = root.text
        prim.exprType = type('PrStr', (object,), {
            'kind': 'StringType',
            'Min': str(len(prim.value) - 2),
            'Max': str(len(prim.value) - 2)
        })
    elif root.type == lexer.FLOAT2:
        prim = ogAST.PrimMantissaBaseExp()
        mant = float(root.getChild(0).toString())
        base = int(root.getChild(1).toString())
        exp = int(root.getChild(2).toString())
        # Compute mantissa * base**exponent to get the value type range
        value = float(mant * pow(base, exp))
        prim.value = {'mantissa': mant, 'base': base, 'exponent': exp}
        prim.exprType = type('PrMantissa', (object,), {
            'kind': 'RealType',
            'Min': str(value),
            'Max': str(value)
        })
    elif root.type == lexer.EMPTYSTR:
        # Empty SEQUENCE OF (i.e. "{}")
        prim = ogAST.PrimEmptyString()
        prim.exprType = type('PrES', (object,), {
            'kind': 'SequenceOfType',
            'Min': '0',
            'Max': '0'
        })
    elif root.type == lexer.CHOICE:
        prim = ogAST.PrimChoiceItem()
        choice = root.getChild(0).toString()
        expr, err, warn = expression(root.getChild(1), context)
        errors.extend(err)
        warnings.extend(warn)
        prim.value = {'choice': choice, 'value': expr}
        prim.exprType = UNKNOWN_TYPE
    elif root.type == lexer.SEQUENCE:
        prim = ogAST.PrimSequence()
        prim.value = {}
        for elem in root.getChildren():
            if elem.type == lexer.ID:
                field_name = elem.text
            else:
                prim.value[field_name], err, warn = (expression(elem, context))
                errors.extend(err)
                warnings.extend(warn)
        prim.exprType = UNKNOWN_TYPE
    elif root.type == lexer.SEQOF:
        prim = ogAST.PrimSequenceOf()
        prim.value = []
        for elem in root.getChildren():
            # SEQUENCE OF elements cannot have fieldnames/indexes
            prim_elem, prim_elem_errors, prim_elem_warnings = \
                                                        primary(elem, context)
            errors += prim_elem_errors
            warnings += prim_elem_warnings
            prim_elem.inputString = get_input_string(elem)
            prim_elem.line = elem.getLine()
            prim_elem.charPositionInLine = elem.getCharPositionInLine()
            prim.value.append(prim_elem)
        prim.exprType = type('PrSO', (object,), {
            'kind': 'SequenceOfType',
            'Min': str(len(root.children)),
            'Max': str(len(root.children)),
            'type': UNKNOWN_TYPE
        })
    elif root.type == lexer.BITSTR:
        prim = ogAST.PrimBitStringLiteral()
        warnings.append(warning(root, 'Bit string literal not supported yet'))
    elif root.type == lexer.OCTSTR:
        prim = ogAST.PrimOctetStringLiteral()
        warnings.append(
            warning(root, 'Octet string literal not supported yet'))
    else:
        # TODO: return error message
        raise NotImplementedError

    prim.inputString = get_input_string(root)
    prim.tmpVar = tmp()

    return prim, errors, warnings


def variables(root, ta_ast, context):
    ''' Process declarations of variables (dcl a,b Type := 5) '''
    var = []
    errors = []
    warnings = []
    asn1_sort, def_value = UNKNOWN_TYPE, None
    for child in root.getChildren():
        if child.type == lexer.ID:
            var.append(child.text)
        elif child.type == lexer.SORT:
            sort = child.getChild(0).text
            # Find corresponding type in ASN.1 model
            try:
                asn1_sort = sdl_to_asn1(sort)
            except TypeError as err:
                errors.append(error(root, str(err)))
        elif child.type == lexer.GROUND:
            # Default value for a variable - needs to be a ground expression
            def_value, err, warn = expression(child.getChild(0), context)
            errors.extend(err)
            warnings.extend(warn)
            expr = ogAST.ExprAssign()
            expr.left = ogAST.PrimVariable()
            expr.left.inputString = var[-1]
            expr.left.exprType = asn1_sort
            expr.right = def_value
            try:
                fix_expression_types(expr, context)
                def_value = expr.right
            except(AttributeError, TypeError) as err:
                #print (traceback.format_exc())
                errors.append('Types are incompatible in DCL assignment: '
                    'left (' +
                    expr.left.inputString + ', type= ' +
                    type_name(expr.left.exprType) + '), right (' +
                    expr.right.inputString + ', type= ' +
                    type_name(expr.right.exprType) + ') ' + str(err))
            else:
                def_value.exprType = asn1_sort

            if not def_value.is_raw and not is_constant(def_value):
                errors.append('In variable declaration {}: default'
                              ' value is not a valid ground expression'.
                              format(var[-1]))
        else:
            warnings.append('Unsupported variables construct type: ' +
                    str(child.type))
    for variable in var:
        # Add to the context and text area AST entries
        context.variables[variable] = (asn1_sort, def_value)
        ta_ast.variables[variable] = (asn1_sort, def_value)
    if not DV:
        errors.append('Cannot do semantic checks on variable declarations')
    return errors, warnings


def dcl(root, ta_ast, context):
    ''' Process a set of variable declarations '''
    errors = []
    warnings = []
    for child in root.getChildren():
        if child.type == lexer.VARIABLES:
            err, warn = variables(child, ta_ast, context)
            errors.extend(err)
            warnings.extend(warn)
        else:
            warnings.append(
                    'Unsupported dcl construct, type: ' + str(child.type))
    return errors, warnings


def fpar(root):
    ''' Process a formal parameter declaration '''
    errors = []
    warnings = []
    params = []
    asn1_sort = UNKNOWN_TYPE
    for param in root.getChildren():
        param_names = []
        sort = ''
        direction = 'in'
        assert param.type == lexer.PARAM
        for child in param.getChildren():
            if child.type == lexer.INOUT:
                direction = 'out'
            elif child.type == lexer.IN:
                pass
            elif child.type == lexer.ID:
                # variable name
                param_names.append(child.text)
            elif child.type == lexer.SORT:
                sort = child.getChild(0).text
                try:
                    asn1_sort = sdl_to_asn1(sort)
                except TypeError as err:
                    errors.append(str(err) +
                            '(line ' + str(child.getLine()) + ')')
                for name in param_names:
                    params.append({'name': name, 'direction': direction,
                                   'type': asn1_sort})
            else:
                warnings.append(
                        'Unsupported construct in FPAR, type: ' +
                        str(child.type))
    return params, errors, warnings


def composite_state(root, parent=None, context=None):
    ''' Parse a composite state definition '''
    comp = ogAST.CompositeState()
    errors, warnings = [], []
    # Create a list of all inherited data
    try:
        comp.global_variables = dict(context.variables)
        comp.global_variables.update(context.global_variables)
        comp.global_timers = list(context.timers)
        comp.global_timers.extend(list(context.global_timers))
        comp.input_signals = context.input_signals
        comp.output_signals = context.output_signals
        comp.procedures = context.procedures
        comp.operators = dict(context.operators)
    except AttributeError:
        LOG.debug('Procedure context is undefined')
    # Gather the list of states defined in the composite state
    # and map a list of transitionsi to each state
    comp.mapping = {name: [] for name in get_state_list(root)}
    inner_composite, states, floatings, starts = [], [], [], []
    for child in root.getChildren():
        if child.type == lexer.ID:
            comp.line = child.getLine()
            comp.charPositionInLine = child.getCharPositionInLine()
            comp.statename = child.toString().lower()
        elif child.type == lexer.COMMENT:
            comp.comment, _, _ = end(child)
        elif child.type == lexer.IN:
            # state entry point
            for point in child.getChildren():
                comp.state_entrypoints.append(point.toString().lower())
        elif child.type == lexer.OUT:
            # state exit point
            for point in child.getChildren():
                comp.state_exitpoints.append(point.toString().lower())
        elif child.type == lexer.TEXTAREA:
            textarea, err, warn = text_area(child, context=comp)
            errors.extend(err)
            warnings.extend(warn)
            comp.content.textAreas.append(textarea)
        elif child.type == lexer.PROCEDURE:
            new_proc, err, warn = procedure(child, context=comp)
            errors.extend(err)
            warnings.extend(warn)
            if new_proc.inputString.strip().lower() == 'entry':
                comp.entry_procedure = new_proc
            elif new_proc.inputString.strip().lower() == 'exit':
                comp.exit_procedure = new_proc
            comp.content.inner_procedures.append(new_proc)
            # Add procedure to the context, to make it visible at scope level
            context.procedures.append(new_proc)
        elif child.type == lexer.COMPOSITE_STATE:
            inner_composite.append(child)
        elif child.type == lexer.STATE:
            states.append(child)
        elif child.type == lexer.FLOATING_LABEL:
            floatings.append(child)
        elif child.type == lexer.START:
            starts.append(child)
        else:
            warnings.append(
                    'Unsupported construct in nested state, type: ' +
                    str(child.type) + ' - line ' + str(child.getLine()) +
                    ' - state name: ' + str(comp.statename))
    for each in inner_composite:
        # Parse inner composite states after the text areas to make sure
        # that all variables are propagated to the the inner scope
        inner, err, warn = composite_state(each, parent=None,
                                           context=comp)
        errors.extend(err)
        warnings.extend(warn)
        comp.composite_states.append(inner)
    # Parse other elements after the nested states
    for each in starts:
         # START transition (fills the mapping structure)
        st, err, warn = start(each, context=comp)
        errors.extend(err)
        warnings.extend(warn)
        if st.inputString:
            comp.content.named_start.append(st)
        elif not comp.content.start:
            comp.content.start = st
        else:
            errors.append('Only one unnamed START transition is allowed')
    for each in floatings:
        lab, err, warn = floating_label(each, parent=None, context=comp)
        errors.extend(err)
        warnings.extend(warn)
        comp.content.floating_labels.append(lab)
    for each in states:
        # And parse the states after inner states to make sure all CONNECTS
        # are properly defined.
        # Fill up the 'mapping' structure.
        newstate, err, warn = state(each, parent=None, context=comp)
        errors.extend(err)
        warnings.extend(warn)
        comp.content.states.append(newstate)
    # Post-processing: check that all NEXTSTATEs have a corresponding STATE
    for ns in [t.inputString.lower() for t in comp.terminators
            if t.kind == 'next_state']:
        if not ns in [s.lower() for s in
                comp.mapping.viewkeys()] + ['-']:
            errors.append('In composite state "{}": missing definition '
                         'of substate "{}"'.format(comp.statename, ns.upper()))
    return comp, errors, warnings


def procedure(root, parent=None, context=None):
    ''' Parse a procedure definition '''
    proc = ogAST.Procedure()
    errors = []
    warnings = []
    # Create a list of all inherited data
    try:
        proc.global_variables = dict(context.variables)
        proc.global_variables.update(context.global_variables)
        proc.global_timers = list(context.timers)
        proc.global_timers.extend(list(context.global_timers))
        proc.input_signals = context.input_signals
        proc.output_signals = context.output_signals
        proc.procedures = context.procedures
        proc.operators = dict(context.operators)
    except AttributeError:
        LOG.debug('Procedure context is undefined')
    # Gather the list of states defined in the procedure
    # and create a mapping of transitions to each state
    # (Note, procedures in OG currently do NOT support states)
    proc.mapping = {name: [] for name in get_state_list(root)}
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            proc.pos_x, proc.pos_y, proc.width, proc.height = cif(child)
        elif child.type == lexer.ID:
            proc.line = child.getLine()
            proc.charPositionInLine = child.getCharPositionInLine()
            proc.inputString = child.toString()
        elif child.type == lexer.COMMENT:
            proc.comment, _, ___ = end(child)
        elif child.type == lexer.TEXTAREA:
            textarea, err, warn = text_area(child, context=proc)
            errors.extend(err)
            warnings.extend(warn)
            proc.content.textAreas.append(textarea)
        elif child.type == lexer.PROCEDURE:
            new_proc, err, warn = procedure(child, context=proc)
            errors.extend(err)
            warnings.extend(warn)
            proc.content.inner_procedures.append(new_proc)
            # Add procedure to the context, to make it visible at scope level
            context.procedures.append(new_proc)
        elif child.type == lexer.EXTERNAL:
            proc.external = True
        elif child.type == lexer.FPAR:
            params, err, warn = fpar(child)
            errors.extend(err)
            warnings.extend(warn)
            proc.fpar = params
        elif child.type == lexer.START:
            # START transition (fills the mapping structure)
            proc.content.start, err, warn = start(child, context=proc)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.STATE:
            # STATE - fills up the 'mapping' structure.
            newstate, err, warn = state(child, parent=None, context=proc)
            errors.extend(err)
            warnings.extend(warn)
            proc.content.states.append(newstate)
        elif child.type == lexer.FLOATING_LABEL:
            lab, err, warn = floating_label(child, parent=None, context=proc)
            errors.extend(err)
            warnings.extend(warn)
            proc.content.floating_labels.append(lab)
        else:
            warnings.append(
                    'Unsupported construct in procedure, type: ' +
                    str(child.type) + ' - line ' + str(child.getLine()) +
                    ' - string: ' + str(proc.inputString))
    for each in proc.terminators:
        # check that RETURN statements type is correct
        if not proc.return_type and each.return_expr:
            errors.append('No return value expected in procedure '
                          + proc.inputString)
        elif proc.return_type and each.return_expr:
            check_expr = ogAST.ExprAssign()
            check_expr.left = ogAST.PrimVariable()
            check_expr.left.exprType = proc.return_type
            check_expr.right = each.return_expr
            try:
                fix_expression_types(check_expr, context)
            except (TypeError, AttributeError) as err:
                errors.append(str(err))
            # Id of fd_expr may have changed (enumerated, choice)
            each.return_expr = check_expr.right
        elif proc.return_type and not each.return_expr:
            errors.append('Missing return value in procedure '
                          + proc.inputString)
        else:
            continue
    return proc, errors, warnings


def floating_label(root, parent, context):
    ''' Floating label: name and optional transition '''
    errors = []
    warnings = []
    lab = ogAST.Floating_label()
    # Keep track of the number of terminator statements following the label
    # useful if we want to render graphs from the SDL model
    terminators = len(context.terminators)
    for child in root.getChildren():
        if child.type == lexer.ID:
            lab.inputString = child.text
            lab.line = child.getLine()
            lab.charPositionInLine = child.getCharPositionInLine()
        elif child.type == lexer.CIF:
            # Get symbol coordinates
            lab.pos_x, lab.pos_y, lab.width, lab.height = cif(child)
        elif child.type == lexer.HYPERLINK:
            lab.hyperlink = child.getChild(0).text[1:-1]
        elif child.type == lexer.TRANSITION:
            trans, err, warn = transition(
                                    child, parent=lab, context=context)
            errors.extend(err)
            warnings.extend(warn)
            lab.transition = trans
        else:
            warnings.append(
                    'Unsupported construct in floating label: ' +
                    str(child.type))
    if not lab.transition:
        warnings.append('Floating labels not followed by a transition: ' +
                        str(lab.inputString))
    # At the end of the label parsing, get the the list of terminators that
    # the transition contains by making a diff with the list at context
    # level (we counted the number of terminators before parsing the item)
    lab.terminators = list(context.terminators[terminators:])
    return lab, errors, warnings


def newtype_gettype(root, ta_ast, context):
    ''' Returns the name of the new type created by a NEWTYPE construction '''
    errors = []
    warnings = []
    newtypename = ""
    if (root.getChild(0).type != lexer.SORT):
        warnings.append("Expected SORT in newtype identifier, got type:"
                        + str(root.type))
        return newtypename, errors, warnings

    newtypename = root.getChild(0).getChild(0).text
    return newtypename, errors, warnings


def get_array_type(root):
    ''' Returns the subtype associated to an NEWTYPE ARRAY construction '''
    # indexSort = root.getChild(0).text
    typeSort = root.getChild(1).text
    typeSortLine = root.getChild(1).getLine()
    typeSortChar = root.getChild(1).getCharPositionInLine()

    # Constructing ASN.1 AST subtype
    newtype = type("SeqOf_type", (object,), {
        "Line": typeSortLine, "CharPositionInLine": typeSortChar,
        "Kind": "ReferenceType", "ReferencedTypeName": typeSort
    })

    return newtype


def get_struct_children(root):
    ''' Returns the fields of a STRUCT as a dictionary '''
    children = {}
    fieldlist = root.getChild(0)
    fieldname = ""
    typename = ""
    if (fieldlist.type != lexer.FIELDS):
        return children

    for field in fieldlist.getChildren():
        if (field.type == lexer.FIELD):
            fieldname = field.getChild(0).text
            typename = field.getChild(1).getChild(0).text
            line = field.getChild(0).getLine()
            charpos = field.getChild(0).getCharPositionInLine()

            children[fieldname] = type(str(fieldname), (object,), {
                "Optional": "False", "Line": line,
                "CharPositionInLine": charpos,
                "type": type(str(fieldname + "_type"), (object,), {
                    "Line": line, "CharPositionInLine": charpos,
                    "kind": "ReferenceType", "ReferencedTypeName": typename
                })
            })
    return children


def syntype(root, ta_ast, context):
    ''' Parse a SYNTYPE definition and inject it in ASN1 AST'''
    errors = []
    warnings = []
    newtype = ""
    reftype = ""
    global DV

    newtypename = root.getChild(0).getChild(0).text
    # reftypename = root.getChild(1).getChild(0).text
    newtype = type(str(newtypename), (object,), {
        "Line": root.getChild(0).getLine(),
        "CharPositionInLine": root.getChild(0).getCharPositionInLine(),
    })
    newtype.type = type(str(newtypename) + "_type", (object,), {
        "Line": root.getChild(1).getLine(),
        "CharPositionInLine": root.getChild(1).getCharPositionInLine(),
        "kind": reftype + "Type"
    })

    DV.types[str(newtypename)] = newtype
    LOG.debug("Found new SYNTYPE " + newtypename)
    return errors, warnings


def newtype(root, ta_ast, context):
    ''' Parse a NEWTYPE definition and inject it in ASN1 AST'''
    errors = []
    warnings = []
    global DV

    newtypename, errors, warnings = newtype_gettype(root, ta_ast, context)
    if (newtypename == ""):
        return errors, warnings

    newtype = type(str(newtypename), (object,), {
                   "Line": root.getLine(),
                   "CharPositionInLine": root.getCharPositionInLine()})

    if (root.getChild(1).type == lexer.ARRAY):
        newtype.kind = "SequenceOfType"
        newtype.type = get_array_type(root.getChild(1))
        newtype.Min = "Min"
        newtype.Max = "Max"
        DV.types[str(newtypename)] = newtype
        LOG.debug("Found new ARRAY type " + newtypename)
    elif (root.getChild(1).type == lexer.STRUCT):
        newtype.kind = "SequenceType"
        newtype.Children = get_struct_children(root.getChild(1))
        DV.types[str(newtypename)] = newtype
        LOG.debug("Found new STRUCT type " + newtypename)
    else:
        warnings.append(
                    'Unsupported type definition in newtype, type: ' +
                    str(root.type))
     # STRUCT CASE
    return errors, warnings


def synonym(root, ta_ast, context):
    ''' Parse a SYNONYM definition and inject it in ASN1 exported variables'''
    errors = []
    warnings = []
    global DV

    if not "SDL-Constants" in DV.asn1Modules:
        DV.asn1Modules.append("SDL-Constants")
        DV.exportedVariables["SDL-Constants"] = []

    for child in root.getChildren():
        if child.getChild(0).type == lexer.SORT:
            DV.exportedVariables["SDL-Constants"].append(
                                            child.getChild(0).getChild(0).text)
    return errors, warnings


def text_area_content(root, ta_ast, context):
    ''' Content of a text area: DCL, NEWTYPES, SYNTYPES, SYNONYMS, operators,
        procedures  '''
    errors = []
    warnings = []
    for child in root.getChildren():
        if child.type == lexer.DCL:
            err, warn = dcl(child, ta_ast, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.SYNONYM_LIST:
            err, warn = synonym(child, ta_ast, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.NEWTYPE:
            err, warn = newtype(child, ta_ast, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.SYNTYPE:
            err, warn = syntype(child, ta_ast, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.PROCEDURE:
            proc, err, warn = procedure(child, context=context)
            errors.extend(err)
            warnings.extend(warn)
            # Add procedure to the container (process or procedure)
            context.content.inner_procedures.append(proc)
            # Add to context to make it visible at scope level
            context.procedures.append(proc)
        elif child.type == lexer.FPAR:
            params, err, warn = fpar(child)
            errors.extend(err)
            warnings.extend(warn)
            try:
                if context.fpar:
                    errors.append('Duplicate declaration of FPAR section')
                else:
                    context.fpar = params
            except AttributeError:
                errors.append('Only procedures can have an FPAR section')
        elif child.type == lexer.TIMER:
            context.timers.extend(timer.text.lower()
                                            for timer in child.children)
        else:
            warnings.append(
                    'Unsupported construct in text area content, type: ' +
                    str(child.type))
    return errors, warnings


def text_area(root, parent=None, context=None):
    ''' Process a text area (DCL, procedure, operators declarations '''
    errors = []
    warnings = []
    ta = ogAST.TextArea()
    coord = False
    for child in root.getChildren():
        if child.type == lexer.CIF:
            userTextStartIndex = child.getTokenStopIndex() + 1
            ta.pos_x, ta.pos_y, ta.width, ta.height = cif(child)
            coord = True
        elif child.type == lexer.TEXTAREA_CONTENT:
            ta.line = child.getLine()
            ta.charPositionInLine = child.getCharPositionInLine()
            # Go update the process-level list of variables
            # (TODO: also ops and procedures)
            err, warn = text_area_content(child, ta, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.ENDTEXT:
            userTextStopIndex = child.getTokenStartIndex() - 1
            ta.inputString = token_stream(child).toString(
                    userTextStartIndex, userTextStopIndex).strip()
        elif child.type == lexer.HYPERLINK:
            ta.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported construct in text area, type: ' +
                    str(child.type))
    # Report errors with symbol coordinates
    if coord:
        errors = [[e, [ta.pos_x, ta.pos_y]] for e in errors]
        warnings = [[w, [ta.pos_x, ta.pos_y]] for w in warnings]
    return ta, errors, warnings


def signal(root):
    ''' SIGNAL definition: name and optional list of types '''
    errors, warnings = [], []
    new_signal = {}
    for child in root.getChildren():
        if child.type == lexer.ID:
            new_signal['name'] = child.text
        elif child.type == lexer.PARAMNAMES:
            try:
                param_name, = [par.text for par in child.getChildren()]
                new_signal['param_name'] = param_name
            except ValueError:
                # Will be raised and reported at PARAMS token
                pass
        elif child.type == lexer.PARAMS:
            try:
                param, = [par.text for par in child.getChildren()]
                new_signal['type'] = sdl_to_asn1(param)
            except ValueError:
                errors.append(new_signal['name'] + ' cannot have more' +
                  ' than one parameter. Check signal declaration.')
            except TypeError as err:
                errors.append(str(err))
    return new_signal, errors, warnings


def single_route(root):
    ''' Route (from id to id with [signal id] '''
    route = {'source': root.getChild(0).text,
             'dest': root.getChild(1).text,
             'signals': [sig.text for sig in root.getChildren()[2:]]}
    return route


def channel_signalroute(root):
    ''' Channel/signalroute definition (connections) '''
    # no AST entry for edges - a simple dict is sufficient
    # (name, [route])
    edge = {'routes': []}
    for child in root.getChildren():
        if child.type == lexer.ID:
            edge['name'] = child.text
        elif child.type == lexer.ROUTE:
            edge['routes'].append(single_route(child))
    return edge


def block_definition(root, parent):
    ''' BLOCK entity definition '''
    errors, warnings = [], []
    block = ogAST.Block()
    block.parent = parent
    parent.blocks.append(block)
    for child in root.getChildren():
        if child.type == lexer.ID:
            block.name = child.text
        elif child.type == lexer.SIGNAL:
            sig, err, warn = signal(child)
            errors.extend(err)
            warnings.extend(warn)
            block.signals.append(sig)
        elif child.type == lexer.CONNECTION:
            block.connections.append({'channel': cnx[0].text,
              'signalroute': cnx[1].text} for cnx in child.getChildren())
        elif child.type == lexer.BLOCK:
            block, err, warn = block_definition(child, parent=block)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.PROCESS:
            proc, err, warn = process_definition(child, parent=block)
            block.processes.append(proc)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.SIGNALROUTE:
            sigroute = channel_signalroute(child)
            block.signalroutes.append(sigroute)
        else:
            warnings.append('Unsupported block child type: ' +
                str(child.type))
    return block, errors, warnings


def system_definition(root, parent):
    ''' SYSTEM part - contains blocks, procedures and channels '''
    errors, warnings = [], []
    system = ogAST.System()
    # Store the name of the file where the system is defined
    system.filename = node_filename(root)
    system.ast = parent
    for child in root.getChildren():
        if child.type == lexer.ID:
            system.name = child.text
            LOG.debug('System name: ' + system.name)
        elif child.type == lexer.SIGNAL:
            sig, err, warn = signal(child)
            errors.extend(err)
            warnings.extend(warn)
            system.signals.append(sig)
            LOG.debug('Found signal: ' + str(sig))
        elif child.type == lexer.PROCEDURE:
            LOG.debug('procedure declaration')
            proc, err, warn = procedure(
                    child, parent=None, context=system)
            errors.extend(err)
            warnings.extend(warn)
            system.procedures.append(proc)
            LOG.debug('Added procedure: ' + proc.inputString)
        elif child.type == lexer.CHANNEL:
            LOG.debug('channel declaration')
            channel = channel_signalroute(child)
            system.channels.append(channel)
        elif child.type == lexer.BLOCK:
            LOG.debug('block declaration')
            block, err, warn = block_definition(child, parent=system)
            errors.extend(err)
            warnings.extend(warn)
        else:
            warnings.append('Unsupported construct in system: ' +
                    str(child.type))
    return system, errors, warnings


def process_definition(root, parent=None, context=None):
    ''' Process definition analysis '''
    errors = []
    warnings = []
    process = ogAST.Process()
    process.filename = node_filename(root)
    process.parent = parent
    coord = False
    # Prepare the transition/state mapping
    process.mapping = {name: [] for name in get_state_list(root)}
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            process.pos_x, process.pos_y, process.width, process.height =\
                    cif(child)
            coord = True
        elif child.type == lexer.ID:
            # Get process (taste function) name
            process.processName = child.text
            try:
                # Retrieve process interface (PI/RI)
                async_signals, procedures = get_interfaces(parent, child.text)
                process.input_signals.extend([sig for sig in async_signals
                                             if sig['direction'] == 'in'])
                process.output_signals.extend([sig for sig in async_signals
                                              if sig['direction'] == 'out'])
                process.procedures.extend(procedures)
            except AttributeError as err:
                # No interface because process is defined standalone
                LOG.debug('Discarding process ' + child.text + ' ' + str(err))
            except TypeError as error:
                LOG.debug(str(error))
                errors.append(str(error))
            if coord:
                errors = [[e, [process.pos_x, process.pos_y]] for e in errors]
                warnings = [[w, [process.pos_x, process.pos_y]]
                             for w in warnings]
        elif child.type == lexer.TEXTAREA:
            # Text zone where variables and operators are declared
            textarea, err, warn = text_area(child, context=process)
            errors.extend(err)
            warnings.extend(warn)
            process.content.textAreas.append(textarea)
        elif child.type == lexer.START:
            # START transition (fills the mapping structure)
            process.content.start, err, warn = start(
                    child, context=process)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.STATE:
            # STATE - fills up the 'mapping' structure.
            statedef, err, warn = state(
                    child, parent=None, context=process)
            errors.extend(err)
            warnings.extend(warn)
            process.content.states.append(statedef)
        elif child.type == lexer.NUMBER_OF_INSTANCES:
            # Number of instances - discarded (working on a single process)
            pass
        elif child.type == lexer.PROCEDURE:
            proc, err, warn = procedure(
                    child, parent=None, context=process)
            errors.extend(err)
            warnings.extend(warn)
            process.content.inner_procedures.append(proc)
            # Add it at process level so that it is in the scope
            process.procedures.append(proc)
        elif child.type == lexer.FLOATING_LABEL:
            lab, err, warn = floating_label(
                    child, parent=None, context=process)
            errors.extend(err)
            warnings.extend(warn)
            process.content.floating_labels.append(lab)
        elif child.type == lexer.COMPOSITE_STATE:
            comp, err, warn = composite_state(child,
                                              parent=None,
                                              context=process)
            errors.extend(err)
            warnings.extend(warn)
            process.composite_states.append(comp)
        elif child.type == lexer.REFERENCED:
            process.referenced = True
        elif child.type == lexer.COMMENT:
            process.comment, _, _ = end(child)
        else:
            warnings.append('Unsupported process definition child: ' +
                             sdl92Parser.tokenNames[child.type] +
                            ' - line ' + str(child.getLine()))
    return process, errors, warnings


def input_part(root, parent, context):
    ''' Parse an INPUT - set of TASTE provided interfaces '''
    i = ogAST.Input()
    warnings, errors = [], []
    coord = False
    # Keep track of the number of terminator statements follow the input
    # useful if we want to render graphs from the SDL model
    terminators = len(context.terminators)
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            i.pos_x, i.pos_y, i.width, i.height = cif(child)
            coord = True
        elif child.type == lexer.INPUTLIST:
            i.inputString = get_input_string(child)
            i.line = child.getLine()
            i.charPositionInLine = child.getCharPositionInLine()
            # get input name and parameters (support for one parameter only)
            sig_param_type, user_param_type = None, None
            inputnames = [c for c in child.getChildren()
                                                  if c.type != lexer.PARAMS]
            for inputname in inputnames:
                for inp_sig in context.input_signals:
                    if inp_sig['name'].lower() == inputname.text.lower():
                        i.inputlist.append(inp_sig['name'])
                        sig_param_type = inp_sig.get('type')
                        break
                else:
                    for timer in chain(context.timers, context.global_timers):
                        if timer.lower() == inputname.text.lower():
                            i.inputlist.append(timer.lower())
                            break
                    else:
                        errors.append('Input signal or timer not declared: '
                            + inputname.toString() +
                            ' (line ' + str(i.line) + ')')
            if len(inputnames) > 1 and sig_param_type is not None:
                errors.append('Inputs in a list shall not expect parameters')
            # Parse all parameters (then check that there is only one)
            inputparams = [c.getChildren() for c in child.getChildren()
                                                     if c.type == lexer.PARAMS]
            if len(inputparams) > 1:
                # user entered e.g. INPUT a(x), b(y) instead of INPUT a,b
                errors.append('Only one input can have a parameter')
            elif len(inputparams) == 1 and sig_param_type is not None and \
                    len(inputparams[0]) == 1:
                user_param, = inputparams[0]
                try:
                    user_param_type = find_variable(user_param.text, context)
                    try:
                        compare_types(sig_param_type, user_param_type)
                    except TypeError as err:
                        errors.append('Parameter type does not match with '
                                      'signal declaration (expecting '
                                      'a variable of type ' +
                                      sig_param_type.ReferencedTypeName + ') -'
                                      + str(err))
                    else:
                        # Store parameter only if everything is OK
                        i.parameters = [user_param.text.lower()]
                except AttributeError as err:
                    errors.append(str(err))
            elif inputparams or sig_param_type:
                errors.append('Wrong number of parameters or type mismatch')

            # Report errors with symbol coordinates
            if coord:
                errors = [[e, [i.pos_x, i.pos_y]] for e in errors]
                warnings = [[w, [i.pos_x, i.pos_y]] for w in warnings]
        elif child.type == lexer.ASTERISK:
            # Asterisk means: all inputs not processed explicitely
            # Here we do not set the input list - it is set after
            # all other inputs are processed (see state function)
            i.inputString = get_input_string(child)
            i.line = child.getLine()
            i.charPositionInLine = child.getCharPositionInLine()
        elif child.type == lexer.PROVIDED:
            warnings.append('"PROVIDED" expressions not supported')
            i.provided = 'Provided'
        elif child.type == lexer.TRANSITION:
            trans, err, warn = transition(
                                    child, parent=i, context=context)
            errors.extend(err)
            warnings.extend(warn)
            i.transition = trans
            # Associate a reference to the transition to the list of inputs
            # The reference is an index to process.transitions table
            context.transitions.append(trans)
            i.transition_id = len(context.transitions) - 1
        elif child.type == lexer.COMMENT:
            i.comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            i.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported INPUT child type: ' +
                    str(child.type))
    # At the end of the input parsing, get the the list of terminators that
    # follow the input transition by making a diff with the list at process
    # level (we counted the number of terminators before parsing the input)
    i.terminators = list(context.terminators[terminators:])
    return i, errors, warnings


def state(root, parent, context):
    '''
        Parse a STATE.
        "parent" is used to compute absolute coordinates
        "context" is the AST used to store global data (process/procedure)
    '''
    errors = []
    warnings = []
    state_def = ogAST.State()
    asterisk_state = False
    asterisk_input = None
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            (state_def.pos_x, state_def.pos_y,
            state_def.width, state_def.height) = cif(child)
        elif child.type == lexer.STATELIST:
            # State name(state_def)
            state_def.inputString = get_input_string(child)
            state_def.line = child.getLine()
            state_def.charPositionInLine = child.getCharPositionInLine()
            for statename in child.getChildren():
                state_def.statelist.append(statename.toString())
        elif child.type == lexer.ASTERISK:
            asterisk_state = True
            state_def.inputString = get_input_string(child)
            state_def.line = child.getLine()
            state_def.charPositionInLine = child.getCharPositionInLine()
            exceptions = [c.toString() for c in child.getChildren()]
            for st in context.mapping:
                if st not in (exceptions, 'START'):
                    state_def.statelist.append(st)
        elif child.type == lexer.INPUT:
            # A transition triggered by an INPUT
            inp, err, warn = \
                    input_part(child, parent=state_def, context=context)
            errors.extend(err)
            warnings.extend(warn)
            try:
                for statename in state_def.statelist:
                    context.mapping[statename.lower()].append(inp)
            except KeyError:
                warnings.append('State definition missing')
            state_def.inputs.append(inp)
            if inp.inputString.strip() == '*':
                if asterisk_input:
                    errors.append('Multiple asterisk inputs under state ' +
                            str(state_def.inputString))
                else:
                    asterisk_input = inp
        elif child.type == lexer.CONNECT:
            comp_states = (comp.statename for comp in context.composite_states)
            if asterisk_state or len(state_def.statelist) != 1 \
                    or state_def.statelist[0].lower() not in comp_states:
                errors.append('State {} is not a composite state and cannot '
                              'be followed by a connect statement'
                              .format(state_def.statelist[0]))
            conn_part, err, warn = connect_part(child, state_def, context)
            state_def.connects.append(conn_part)
            warnings.extend(warn)
            errors.extend(err)
        elif child.type == lexer.COMMENT:
            state_def.comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            state_def.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported STATE definition child type: ' +
                str(child.type))
    # post-processing: if state is followed by an ASTERISK input, the exact
    # list of inputs can be updated. Possible only if context has signals
    if context.input_signals and asterisk_input:
        explicit_inputs = set()
        for inp in state_def.inputs:
            explicit_inputs |= set(inp.inputlist)
        # Keep only inputs that are not explicitely defined
        input_signals = (sig['name'] for sig in context.input_signals)
        remaining_inputs = set(input_signals) - explicit_inputs
        asterisk_input.inputlist = list(remaining_inputs)
    # post-processing: if state is composite, add link to the content
    if len(state_def.statelist) == 1 and not asterisk_state:
        for each in context.composite_states:
            if each.statename.lower() == state_def.statelist[0].lower():
                state_def.composite = each

    return state_def, errors, warnings


def connect_part(root, parent, context):
    ''' Connection of a nested state exit point with a transition
        Very similar to INPUT '''
    errors, warnings = [], []
    coord = False
    conn = ogAST.Connect()
    try:
        statename = parent.statelist[0].lower()
    except AttributeError:
        # Ignore missing parent/statelist to allow local syntax check
        statename = ''
    id_token = []
    # Keep track of the number of terminator statements follow the input
    # useful if we want to render graphs from the SDL model
    terms = len(context.terminators)
    # Retrieve composite state
    try:
        nested, = (comp for comp in context.composite_states
                   if comp.statename.lower() == statename.lower())
    except ValueError:
        # Ignore unexisting state - to allow local syntax check
        nested = ogAST.CompositeState()

    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            conn.pos_x, conn.pos_y, conn.width, conn.height = cif(child)
            coord = True
        elif child.type == lexer.ID:
            id_token.append(child)
            conn.connect_list.append(child.toString().lower())
        elif child.type == lexer.ASTERISK:
            id_token.append(child)
            conn.connect_list = nested.state_exitpoints
        elif child.type == lexer.TRANSITION:
            trans, err, warn = transition(child, parent=conn, context=context)
            errors.extend(err)
            warnings.extend(warn)
            context.transitions.append(trans)
            trans_id = len(context.transitions) - 1
            conn.transition_id = trans_id
            conn.transition = trans
        elif child.type == lexer.HYPERLINK:
            conn.hyperlink = child.getChild(0).toString()[1:-1]
        elif child.type == lexer.COMMENT:
            conn.comment, _, _ = end(child)
        else:
            warnings.append('Unsupported CONNECT PART child type: ' +
                            sdl92Parser.tokenNames[child.type])
    if not conn.connect_list:
        conn.connect_list.append('')
    if not id_token:
        conn.inputString = ''
        conn.line = root.getLine()
        conn.charPositionInLine = root.getCharPositionInLine()
    else:
        conn.line = id_token[0].getLine()
        conn.charPositionInLine = id_token[0].getCharPositionInLine()
        conn.inputString = token_stream(id_token[0]).toString(
                                        id_token[0].getTokenStartIndex(),
                                        id_token[-1].getTokenStopIndex())
    for exitp in conn.connect_list:
        if exitp != '' and not exitp in nested.state_exitpoints:
            errors.append('Exit point {ep} not defined in state {st}'
                          .format(ep=exitp, st=statename))
        terminators = [term for term in nested.terminators
                       if term.kind == 'return'
                       and term.inputString.lower() == exitp]
        if not terminators:
            errors.append('No {rs} return statement in nested state {st}'
                          .format(rs=exitp, st=statename))
        for each in terminators:
            # Set next transition, exact id to be found in postprocessing
            each.next_trans = trans
    # Set list of terminators
    conn.terminators = list(context.terminators[terms:])
    # Report errors with symbol coordinates
    if coord:
        errors = [[e, [conn.pos_x, conn.pos_y]] for e in errors]
        warnings = [[w, [conn.pos_x, conn.pos_y]] for w in warnings]
    return conn, errors, warnings


def cif(root):
    ''' Return the CIF coordinates '''
    result = []
    for child in root.getChildren():
        if child.type == lexer.DASH:
            val = -int(child.getChild(0).toString())
        else:
            val = int(child.toString())
        result.append(val)
    return result


def start(root, parent=None, context=None):
    ''' Parse the START transition '''
    errors = []
    warnings = []
    if isinstance(context, ogAST.Procedure):
        s = ogAST.Procedure_start()
    elif isinstance(context, ogAST.CompositeState):
        s = ogAST.CompositeState_start()
    else:
        s = ogAST.Start()
    # Keep track of the number of terminator statements following the start
    # useful if we want to render graphs from the SDL model
    terminators = len(context.terminators)
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            s.pos_x, s.pos_y, s.width, s.height = cif(child)
        elif child.type == lexer.ID:
            # in nested states, START can be followed by the entry point name
            s.inputString = child.toString().lower() + '_START'
        elif child.type == lexer.TRANSITION:
            s.transition, err, warn = transition(
                                        child, parent=s, context=context)
            errors.extend(err)
            warnings.extend(warn)
            context.transitions.append(s.transition)
            context.mapping[s.inputString or 'START'] = \
                                                   len(context.transitions) - 1
        elif child.type == lexer.COMMENT:
            s.comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            s.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('START unsupported child type: ' +
                    str(child.type))
    # At the end of the START parsing, get the the list of terminators that
    # follow the START transition by making a diff with the list at process
    # level (we counted the number of terminators before parsing the START)
    s.terminators = list(context.terminators[terminators:])
    return s, errors, warnings


def end(root, parent=None, context=None):
    ''' Parse a comment symbol '''
    c = ogAST.Comment()
    c.line = root.getLine()
    c.charPositionInLine = root.getCharPositionInLine()
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            c.pos_x, c.pos_y, c.width, c.height = cif(child)
        elif child.type == lexer.STRING:
            c.inputString = child.toString()[1:-1]
        elif child.type == lexer.HYPERLINK:
            c.hyperlink = child.getChild(0).toString()[1:-1]
    return c, [], []


def procedure_call(root, parent, context):
    ''' Parse a PROCEDURE CALL (synchronous required interface) '''
    # Same as OUTPUT for external procedures
    out_ast = ogAST.ProcedureCall()
    _, err, warn = output(root, parent, out_ast, context)
    return out_ast, err, warn


def outputbody(root, context):
    ''' Parse an output body (the content excluding the CIF statement) '''
    errors = []
    warnings = []
    body = {'outputName': '', 'params': []}
    for child in root.getChildren():
        if child.type == lexer.ID:
            body['outputName'] = child.text
            if child.text.lower() not in valid_output(context):
                errors.append('"' + child.text +
                              '" is not defined in the current scope')
        elif child.type == lexer.PARAMS:
            body['params'], err, warn = expression_list(
                                                    child, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.TO:
            pass
        # TODO: better support of TO primitive
        else:
            warnings.append('Unsupported output body type:' +
                    str(child.type))
    # Check/set the type of each param
    try:
        check_and_fix_op_params(body.get('outputName', ''),
                                body.get('params', []),
                                context)
    except (AttributeError, TypeError) as op_err:
        errors.append(str(op_err) + ' - ' + get_input_string(root))
        LOG.debug('[outputbody] call check_and_fix_op_params : '
                    + get_input_string(root) + str(op_err))
        LOG.debug(str(traceback.format_exc()))
    if body['params']:
        body['tmpVars'] = []
        for _ in body['params']:
            body['tmpVars'].append(tmp())
    return body, errors, warnings


def output(root, parent, out_ast=None, context=None):
    ''' Parse an OUTPUT :  set of asynchronous required interface(s) '''
    errors = []
    warnings = []
    coord = False
    out_ast = out_ast or ogAST.Output()  # syntax checker passes no ast
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            out_ast.pos_x, out_ast.pos_y, out_ast.width, out_ast.height = \
                    cif(child)
            coord = True
        elif child.type == lexer.OUTPUT_BODY:
            out_ast.inputString = get_input_string(child)
            out_ast.line = child.getLine()
            out_ast.charPositionInLine = child.getCharPositionInLine()
            body, err, warn = outputbody(child, context)
            errors.extend(err)
            warnings.extend(warn)
            out_ast.output.append(body)
        elif child.type == lexer.COMMENT:
            out_ast.comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            out_ast.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported output child type: ' +
                    str(child.type))
    # Report errors with symbol coordinates
    if coord:
        errors = [[e, [out_ast.pos_x, out_ast.pos_y]] for e in errors]
        warnings = [[w, [out_ast.pos_x, out_ast.pos_y]] for w in warnings]
    return out_ast, errors, warnings


def alternative_part(root, parent, context):
    ''' Parse a decision answer '''
    errors = []
    warnings = []
    ans = ogAST.Answer()
    coord = False
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            ans.pos_x, ans.pos_y, ans.width, ans.height = cif(child)
            coord = True
        elif child.type == lexer.CLOSED_RANGE:
            ans.kind = 'closed_range'
            cl0, err0, warn0 = expression(child.getChild(0), context)
            cl1, err1, warn1 = expression(child.getChild(1), context)
            errors.extend(err0)
            errors.extend(err1)
            warnings.extend(warn0)
            warnings.extend(warn1)
            ans.closedRange = [cl0, cl1]
        elif child.type == lexer.CONSTANT:
            ans.kind = 'constant'
            ans.constant, err, warn = expression(
                                        child.getChild(0), context)
            errors.extend(err)
            warnings.extend(warn)
            ans.openRangeOp = ogAST.ExprEq
        elif child.type == lexer.OPEN_RANGE:
            ans.kind = 'open_range'
            for c in child.getChildren():
                if c.type == lexer.CONSTANT:
                    ans.constant, err, warn = expression(
                            c.getChild(0), context)
                    errors.extend(err)
                    warnings.extend(warn)
                    if not ans.openRangeOp:
                        ans.openRangeOp = ogAST.ExprEq
                else:
                    ans.openRangeOp = EXPR_NODE[c.type]
        elif child.type == lexer.INFORMAL_TEXT:
            ans.kind = 'informal_text'
            ans.informalText = child.getChild(0).toString()[1:-1]
        elif child.type == lexer.TRANSITION:
            ans.transition, err, warn = transition(
                                        child, parent=ans, context=context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.HYPERLINK:
            ans.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported answer type: ' + str(child.type))
        if child.type in (lexer.CLOSED_RANGE, lexer.CONSTANT,
                          lexer.OPEN_RANGE, lexer.INFORMAL_TEXT):
            ans.inputString = get_input_string(child)
            ans.line = child.getLine()
            ans.charPositionInLine = child.getCharPositionInLine()
            # Report errors with symbol coordinates
            if coord:
                errors = [[e, [ans.pos_x, ans.pos_y]] for e in errors]
                warnings = [[w, [ans.pos_x, ans.pos_y]] for w in warnings]
    return ans, errors, warnings


def decision(root, parent, context):
    ''' Parse a DECISION '''
    errors = []
    warnings = []
    dec = ogAST.Decision()
    dec.tmpVar = tmp()
    has_else = False
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            dec.pos_x, dec.pos_y, dec.width, dec.height = cif(child)
        elif child.type == lexer.QUESTION:
            dec.kind = 'question'
            decisionExpr, err, warn = expression(
                                        child.getChild(0), context)
            for e in err:
                errors.append([e, [dec.pos_x, dec.pos_y]])
            for w in warn:
                warnings.append([w, [dec.pos_x, dec.pos_y]])
            dec.question = decisionExpr
            dec.inputString = dec.question.inputString
            dec.line = dec.question.line
            dec.charPositionInLine = dec.question.charPositionInLine
        elif child.type == lexer.INFORMAL_TEXT:
            dec.kind = 'informal_text'
            dec.inputString = get_input_string(child)
            dec.informalText = child.getChild(0).toString()[1:-1]
            dec.line = child.getLine()
            dec.charPositionInLine = child.getCharPositionInLine()
        elif child.type == lexer.ANY:
            dec.kind = 'any'
        elif child.type == lexer.COMMENT:
            dec.comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            dec.hyperlink = child.getChild(0).toString()[1:-1]
        elif child.type == lexer.ANSWER:
            ans, err, warn = alternative_part(child, parent, context)
            errors.extend(err)
            warnings.extend(warn)
            dec.answers.append(ans)
        elif child.type == lexer.ELSE:
            a = ogAST.Answer()
            a.inputString = child.toString()
            for c in child.getChildren():
                if c.type == lexer.CIF:
                    a.pos_x, a.pos_y, a.width, a.height = cif(c)
                elif c.type == lexer.TRANSITION:
                    a.transition, err, warn = transition(
                                            c, parent=a, context=context)
                    errors.extend(err)
                    warnings.extend(warn)
                elif child.type == lexer.HYPERLINK:
                    a.hyperlink = child.getChild(0).toString()[1:-1]
            a.kind = 'else'
            dec.answers.append(a)
            has_else = True
        else:
            warnings.append(['Unsupported DECISION child type: ' +
                str(child.type), [dec.pos_x, dec.pos_y]])
    # Make type checks to be sure that question and answers are compatible
    covered_ranges = defaultdict(list)
    qmin, qmax = 0, 0
    need_else = False
    for ans in dec.answers:
        if ans.kind in ('constant', 'open_range'):
            expr = ans.openRangeOp()
            expr.left = dec.question
            expr.right = ans.constant
            try:
                fix_expression_types(expr, context)
                if dec.question.exprType == UNKNOWN_TYPE:
                    dec.question = expr.left
                ans.constant = expr.right
                q_basic = find_basic_type(dec.question.exprType)
                a_basic = find_basic_type(ans.constant.exprType)
                if not q_basic.kind.startswith('Integer'):
                    continue
                # numeric type -> find the range covered by this answer
                if a_basic.Min != a_basic.Max:
                    # Not a constant or a raw number, range is not fix
                    need_else = True
                    continue
                val_a = int(float(a_basic.Min))
                qmin, qmax = int(float(q_basic.Min)), int(float(q_basic.Max))
                # Check the operator to compute the range
                reachable = True
                if ans.openRangeOp == ogAST.ExprLe:
                    if qmin <= val_a:
                        covered_ranges[ans].append((qmin, val_a))
                    else:
                        reachable = False
                elif ans.openRangeOp == ogAST.ExprLt:
                    if qmin < val_a:
                        covered_ranges[ans].append((qmin, val_a - 1))
                    else:
                        reachable = False
                elif ans.openRangeOp == ogAST.ExprGt:
                    if qmax > val_a:
                        covered_ranges[ans].append((val_a + 1, qmax))
                    else:
                        reachable = False
                elif ans.openRangeOp == ogAST.ExprGe:
                    if qmax >= val_a:
                        covered_ranges[ans].append((val_a, qmax))
                    else:
                        reachable = False
                elif ans.openRangeOp == ogAST.ExprEq:
                    if qmin <= val_a <= qmax:
                        covered_ranges[ans].append((val_a, val_a))
                    else:
                        reachable = False
                elif ans.openRangeOp == ogAST.ExprNeq:
                    if qmin == val_a:
                        covered_ranges[ans].append((qmin + 1, qmax))
                    elif qmax == val_a:
                        covered_ranges[ans].append((qmin, qmax - 1))
                    elif qmin < val_a < qmax:
                        covered_ranges[ans].append((qmin, val_a - 1))
                        covered_ranges[ans].append((val_a + 1, qmax))
                    else:
                        warnings.append('Condition is always true: {} /= {}'
                                        .format(dec.inputString,
                                                ans.inputString))
                else:
                    warnings.append('Unsupported range expression')
                if not reachable:
                        warnings.append('Decision "{}": '
                                        'Unreachable branch "{}"'
                                        .format(dec.inputString,
                                                ans.inputString))
            except (AttributeError, TypeError) as err:
                errors.append('Types are incompatible in DECISION: '
                    'question (' + expr.left.inputString + ', type= ' +
                    type_name(expr.left.exprType) + '), answer (' +
                    expr.right.inputString + ', type= ' +
                    type_name(expr.right.exprType) + ') ' + str(err))
        elif ans.kind == 'closed_range':
            if not is_numeric(dec.question.exprType):
                errors.append('Closed range are only for numerical types')
                continue
            for ast_type, idx in zip((ogAST.ExprGe, ogAST.ExprLe), (0, 1)):
                expr = ast_type()
                expr.left = dec.question
                expr.right = ans.closedRange[idx]
                try:
                    fix_expression_types(expr, context)
                    if dec.question.exprType == UNKNOWN_TYPE:
                        dec.question = expr.left
                    ans.closedRange[idx] = expr.right
                except (AttributeError, TypeError) as err:
                    errors.append('Types are incompatible in DECISION: '
                        'question (' + expr.left.inputString + ', type= ' +
                        type_name(expr.left.exprType) + '), answer (' +
                        expr.right.inputString + ', type= ' +
                        type_name(expr.right.exprType) + ') ' + str(err))
            q_basic = find_basic_type(dec.question.exprType)
            if not q_basic.kind.startswith('Integer'):
                continue
            # numeric type -> find the range covered by this answer
            a0_basic = find_basic_type(ans.closedRange[0].exprType)
            a1_basic = find_basic_type(ans.closedRange[1].exprType)
            if a0_basic.Min != a0_basic.Max or a1_basic.Min != a1_basic.Max:
                # Not a constant or a raw number, range is not fix
                need_else = True
                continue
            qmin, qmax = int(float(q_basic.Min)), int(float(q_basic.Max))
            a0_val = int(float(a0_basic.Min))
            a1_val = int(float(a1_basic.Max))
            if a0_val < qmin:
                warnings.append('Decision "{dec}": '
                                'Range [{a0} .. {qmin}] is unreachable'
                                .format(a0=a0_val, qmin=qmin - 1,
                                        dec=dec.inputString))
            if a1_val > qmax:
                warnings.append('Decision "{dec}": '
                                'Range [{qmax} .. {a1}] is unreachable'
                                .format(qmax=qmax + 1, a1=a1_val,
                                        dec=dec.inputString))
            if (a0_val < qmin and a1_val < qmin) or (a0_val > qmax and
                                                     a1_val > qmax):
                warnings.append('Decision "{dec}": Unreachable branch {l}:{h}'
                                .format(dec=dec.inputString,
                                        l=a0_val, h=a1_val))
            covered_ranges[ans].append((int(float(a0_basic.Min)),
                                        int(float(a1_basic.Max))))
    # Check the following:
    # (1) no overlap between covered ranges in decision answers
    # (2) no gap in the coverage of the decision possible values
    # (3) ELSE branch, if present, can be reached
    # (4) if an answer uses a non-ground expression an ELSE is there

    q_ranges = [(qmin, qmax)] if is_numeric(dec.question.exprType) else []
    for each in combinations(covered_ranges.viewitems(), 2):
        for comb in combinations(
                chain.from_iterable(val[1] for val in each), 2):
            comb_overlap = (max(comb[0][0], comb[1][0]),
                            min(comb[0][1], comb[1][1]))
            if comb_overlap[0] <= comb_overlap[1]:
                # (1) - check for overlaps
                errors.append('Decision "{d}": answers {a1} and {a2} '
                              'are overlapping in range [{o1} .. {o2}]'
                              .format(d=dec.inputString,
                                      a1=each[0][0].inputString,
                                      a2=each[1][0].inputString,
                                      o1=comb_overlap[0],
                                      o2=comb_overlap[1]))
    new_q_ranges = []
#   for minq, maxq in q_ranges:
    # (2) Check that decision range is fully covered
    for ans_ref, ranges in covered_ranges.viewitems():
        for mina, maxa in ranges:
            for minq, maxq in q_ranges:
                left = (minq, min(maxq, mina - 1))
                right = (max(minq, maxa + 1), maxq)
                if mina > minq and maxa < maxq:
                    new_q_ranges.extend([left, right])
                elif mina <= minq and maxa >= maxq:
                    pass
                elif mina <= minq:
                    new_q_ranges.append(right)
                elif maxa >= maxq:
                    new_q_ranges.append(left)
            q_ranges, new_q_ranges = new_q_ranges, []
    if not has_else:
        for minq, maxq in q_ranges:
            errors.append('Decision "{}": No answer to cover range [{} .. {}]'
                          .format(dec.inputString, minq, maxq))
    elif has_else and is_numeric(dec.question.exprType) and not q_ranges:
        # (3) Check that ELSE branch is reachable
        warnings.append('Decision "{}": ELSE branch is unreachable'
                        .format(dec.inputString))

    if need_else and not has_else:
        # (4) Answers use non-ground expression -> there should be an ELSE
        warnings.append('Decision "{}": Missing ELSE branch'
                        .format(dec.inputString))

    return dec, errors, warnings


def nextstate(root, context):
    ''' Parse a NEXTSTATE [VIA State_Entry_Point] - detect various kinds of
        errors when trying to enter a nested state '''
    next_state_id, via, entrypoint = '', None, None
    errors = []
    for child in root.getChildren():
        if child.type == lexer.ID:
            next_state_id = child.text
        elif child.type == lexer.DASH:
            next_state_id = '-'
        elif child.type == lexer.VIA:
            if next_state_id.strip() != '-':
                via = get_input_string(root).replace(
                                                'NEXTSTATE', '', 1).strip()
                entrypoint = child.getChild(0).text
                try:
                    composite, = (comp for comp in context.composite_states
                                  if comp.statename.lower()
                                                == next_state_id.lower())
                except ValueError:
                    errors.append('State {} is not a composite state'
                                    .format(next_state_id))
                else:
                    if entrypoint.lower() not in composite.state_entrypoints:
                        errors.append('State {s} has no "{p}" entrypoint'
                                       .format(s=next_state_id, p=entrypoint))
                    for each in composite.content.named_start:
                        if each.inputString == entrypoint.lower() + '_START':
                            break
                    else:
                        errors.append('Entrypoint {p} in state {s} is '
                                      'declared but not defined'.format
                                      (s=next_state_id, p=entrypoint))
            else:
                errors.append('"History" NEXTSTATE cannot have a "via" clause')
        else:
            errors.append('NEXTSTATE undefined construct')
        if not via:
            # check that if the nextstate is nested, it has a START symbol
            try:
                composite, = (comp for comp in context.composite_states
                          if comp.statename.lower() == next_state_id.lower())
                if not composite.content.start:
                    errors.append('Composite state "{}" has no unnamed '
                                  'START symbol'.format(composite.statename))
            except ValueError:
                pass
    return next_state_id, via, entrypoint, errors


def terminator_statement(root, parent, context):
    ''' Parse a terminator (NEXTSTATE, JOIN, STOP) '''
    errors = []
    warnings = []
    t = ogAST.Terminator()
    coord = False
    for term in root.getChildren():
        if term.type == lexer.CIF:
            t.pos_x, t.pos_y, t.width, t.height = cif(term)
            coord = True
        elif term.type == lexer.LABEL:
            lab, err, warn = label(term, parent=parent)
            errors.extend(err)
            warnings.extend(warn)
            t.label = lab
            context.labels.append(lab)
            lab.terminators = [t]
        elif term.type == lexer.NEXTSTATE:
            t.kind = 'next_state'
            t.inputString, t.via, t.entrypoint, err = nextstate(term, context)
            if err:
                errors.extend(err)
            t.line = term.getChild(0).getLine()
            t.charPositionInLine = term.getChild(0).getCharPositionInLine()
            # Add next state infos at process level
            # Used in rendering backends to merge a NEXTSTATE with a STATE
            context.terminators.append(t)
            # post-processing: if nextatate is nested, add link to the content
            # (normally handled at state level, but if state is not defined
            # standalone, the nextstate must hold the composite content)
            if t.inputString != '-':
                for each in context.composite_states:
                    if each.statename.lower() == t.inputString.lower():
                        t.composite = each
        elif term.type == lexer.JOIN:
            t.kind = 'join'
            t.inputString = term.getChild(0).toString()
            t.line = term.getChild(0).getLine()
            t.charPositionInLine = term.getChild(0).getCharPositionInLine()
            context.terminators.append(t)
        elif term.type == lexer.STOP:
            t.kind = 'stop'
            context.terminators.append(t)
        elif term.type == lexer.RETURN:
            t.kind = 'return'
            if term.children:
                t.return_expr, err, warn = expression(
                        term.getChild(0), context)
                t.inputString = t.return_expr.inputString
                errors.extend(err)
                warnings.extend(warn)
            context.terminators.append(t)
        elif term.type == lexer.COMMENT:
            t.comment, _, _ = end(term)
        elif term.type == lexer.HYPERLINK:
            t.hyperlink = term.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported terminator type: ' +
                    str(term.type))
    # Report errors with symbol coordinates
    if coord:
        errors = [[e, [t.pos_x, t.pos_y]] for e in errors]
        warnings = [[w, [t.pos_x, t.pos_y]] for w in warnings]
    return t, errors, warnings


def transition(root, parent, context):
    ''' Parse a transition '''
    errors = []
    warnings = []
    trans = ogAST.Transition()
    # Used to list terminators in this transition
    terminators = {'trans': len(context.terminators)}
    #terminators = len(context.terminators)
    for child in root.getChildren():
        if child.type == lexer.PROCEDURE_CALL:
            proc_call, err, warn = procedure_call(
                            child, parent=parent, context=context)
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(proc_call)
            parent = proc_call
        elif child.type == lexer.LABEL:
            term_count = len(context.terminators)
            lab, err, warn = label(child, parent=parent)
            terminators[lab] = term_count
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(lab)
            parent = lab
            context.labels.append(lab)
        elif child.type == lexer.TASK:
            tas, err, warn = task(
                            child, parent=parent, context=context)
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(tas)
            parent = tas
        elif child.type == lexer.TASK_BODY:
            t, err, warn = task_body(child, context)
            t.inputString = get_input_string(child)
            t.line = child.getLine()
            t.charPositionInLine = child.getCharPositionInLine()
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(t)
            parent = t
        elif child.type == lexer.OUTPUT:
            out_ast = ogAST.Output()
            _, err, warn = output(child,
                               parent=parent,
                               out_ast=out_ast,
                               context=context)
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(out_ast)
            parent = out_ast
        elif child.type == lexer.DECISION:
            dec, err, warn = decision(
                            child, parent=parent, context=context)
            errors.extend(err)
            warnings.extend(warn)
            trans.actions.append(dec)
            parent = dec
        elif child.type == lexer.TERMINATOR:
            term, err, warn = terminator_statement(child,
                    parent=parent, context=context)
            errors.extend(err)
            warnings.extend(warn)
            trans.terminator = term
        else:
            warnings.append('Unsupported symbol in transition, type: ' +
                    str(child.type))
    # At the end of the transition parsing, get the the list of terminators
    # the transition contains by making a diff with the list at context
    # level (we counted the number of terminators before parsing the item)
    trans.terminators = list(context.terminators[terminators.pop('trans'):])
    # Also update the list of terminators of each label in the transition
    for lab, term_count in terminators.viewitems():
        lab.terminators = list(context.terminators[term_count:])
    return trans, errors, warnings


def assign(root, context):
    ''' Parse an assignation (a := b) in a task symbol '''
    errors = []
    warnings = []
    expr = ogAST.ExprAssign(
        get_input_string(root),
        root.getLine(),
        root.getCharPositionInLine()
    )
    expr.kind = 'assign'

    if root.children[0].type == lexer.CALL:
        expr.left, err, warn = call_expression(root.children[0], context)
    elif root.children[0].type == lexer.SELECTOR:
        expr.left, err, warn = selector_expression(root.children[0], context)
    else:
        expr.left, err, warn = primary_variable(root.children[0], context)
    warnings.extend(warn)
    errors.extend(err)

    expr.right, err, warn = expression(root.children[1], context)
    errors.extend(err)
    warnings.extend(warn)

    try:
        fix_expression_types(expr, context)
        # Assignment with numerical value: check range
        basic = find_basic_type(expr.left.exprType)
        if basic.kind.startswith(('Integer', 'Real')):
            check_range(basic, find_basic_type(expr.right.exprType))
    except(AttributeError, TypeError) as err:
        errors.append('Types are incompatible in assignment: left (' +
            expr.left.inputString + ', type= ' +
            type_name(expr.left.exprType) + '), right (' +
            expr.right.inputString + ', type= ' +
            (type_name(expr.right.exprType)
                if expr.right.exprType else 'Unknown') + ') ' + str(err))
    else:
        expr.right.exprType = expr.left.exprType

    return expr, errors, warnings


def for_range(root, context):
    ''' Parse a RANGE statement (in a FOR loop) '''
    errors = []
    warnings = []
    # start and stop are expressions
    result = {'start': None, 'stop': None, 'step': 1}
    expr = []
    for child in root.getChildren():
        if child.type == lexer.GROUND:
            ground, err, warn = expression(child.getChild(0), context)
            errors.extend(err)
            warnings.extend(warn)
            expr.append(ground)
        elif child.type == lexer.INT:
            result['step'] = int(child.text)
        else:
            warnings.append('Unsupported child type in RANGE: ' +
                            str(child.type))
    for range_item in expr:
        if not range_item:
            errors.append('Range must use a ground expression: '
                          + range_item.inputString)
    if len(expr) == 2:
        result['start'], result['stop'] = expr
    elif len(expr) == 1:
        result['stop'] = expr[0]
    else:
        errors.append('Incorrect range expression')
    return result, errors, warnings


def for_loop(root, context):
    ''' Parse a FOR LOOP in a task symbol '''
    errors = []
    warnings = []
    forloop = {'var': '', 'type': None,
               'list': '', 'range': None,
               'transition': None}
    for child in root.getChildren():
        if child.type == lexer.ID:
            forloop['var'] = child.text
            # Implicit variable declaration for the iterator
            context_scope = dict(context.variables)
        elif child.type == lexer.VARIABLE:
            forloop['list'], err, warn = primary_variable(child, context)
            warnings.extend(warn)
            errors.extend(err)
        elif child.type == lexer.CALL:
            forloop['list'], err, warn = call_expression(child, context)
            warnings.extend(warn)
            errors.extend(err)
        elif child.type == lexer.SELECTOR:
            forloop['list'], err, warn = selector_expression(child, context)
            warnings.extend(warn)
            errors.extend(err)
        elif child.type == lexer.RANGE:
            forloop['range'], err, warn = for_range(child, context)
            errors.extend(err)
            warnings.extend(warn)
        elif child.type == lexer.TRANSITION:
            # First we need to define the type of the iterator (and check it)
            if forloop['list']:
                basic_type = find_basic_type(forloop['list'].exprType)
                if basic_type.kind != 'SequenceOfType':
                    errors.append('Variable {} is not iterable'
                                  .format(forloop['list'].inputString))
                else:
                    forloop['type'] = basic_type.type
                    # Set the type of the iterator
                    context.variables[forloop['var']] = (forloop['type'], 0)
            else:
                # Using a range - set type of iterator to standard integer
                start_expr, stop_expr = forloop['range']['start'], \
                                        forloop['range']['stop']
                if not start_expr:
                    r_min = '0'
                else:
                    basic = find_basic_type(start_expr.exprType)
                    r_min = basic.Min if basic != UNKNOWN_TYPE else '0'
                basic = find_basic_type(stop_expr.exprType)
                r_max = basic.Max if basic != UNKNOWN_TYPE else '4294967295'
                # basic may be UNKNOWN_TYPE if the expression is a
                # reference to an ASN.1 constant - their values are not
                # currently visible to the SDL parser
                result_type = type('for_range', (INT32,), {'Min': r_min,
                                                           'Max': r_max})
                context.variables[forloop['var']] = (result_type, 0)

            forloop['transition'], err, warn = transition(
                                    child, parent=for_loop, context=context)
            errors.extend(err)
            warnings.extend(warn)
        else:
            warnings.append('Unsupported child type in FOR body' +
                            str(child.type))
    context.variables = context_scope
    return forloop, errors, warnings


def task_body(root, context):
    ''' Parse the body of a task (excluding CIF and TASK tokens) '''
    errors = []
    warnings = []
    body = None
    for child in root.getChildren():
        if child.type == lexer.ASSIGN:
            if not body:
                body = ogAST.TaskAssign()
            assig, err, warn = assign(child, context)
            errors.extend(err)
            warnings.extend(warn)
            body.elems.append(assig)
        elif child.type == lexer.INFORMAL_TEXT:
            if not body:
                body = ogAST.TaskInformalText()
            body.elems.append(child.getChild(0).toString()[1:-1])
        elif child.type == lexer.FOR:
            if not body:
                body = ogAST.TaskForLoop()
            forloop, err, warn = for_loop(child, context)
            errors.extend(err)
            warnings.extend(warn)
            body.elems.append(forloop)
        else:
            warnings.append('Unsupported child type in task body: ' +
                    str(child.type))
    if not body:
        body = ogAST.TaskAssign()
    return body, errors, warnings


def task(root, parent=None, context=None):
    ''' Parse a TASK symbol (assignation or informal text) '''
    errors = []
    warnings = []
    coord = False
    comment, body = None, None
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            pos_x, pos_y, width, height = cif(child)
            coord = True
        elif child.type == lexer.TASK_BODY:
            body, task_err, task_warn = task_body(child, context)
            body.inputString = get_input_string(child)
            body.line = child.getLine()
            body.charPositionInLine = child.getCharPositionInLine()
            errors.extend(task_err)
            warnings.extend(task_warn)
        elif child.type == lexer.COMMENT:
            comment, _, _ = end(child)
        elif child.type == lexer.HYPERLINK:
            body.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append('Unsupported child type in task definition: ' +
                    str(child.type))
    # Report errors with symbol coordinates
    if coord and body:
        body.pos_x, body.pos_y, body.width, body.height = \
                pos_x, pos_y, width, height
        errors = [[e, [pos_x, pos_y]] for e in errors]
        warnings = [[w, [pos_x, pos_y]] for w in warnings]
    if body:
        body.comment = comment
    else:
        warnings.append('TASK missing content')
        body = ogAST.TaskAssign()
    return body, errors, warnings


def label(root, parent, context=None):
    ''' Parse a LABEL symbol '''
    errors = []
    warnings = []
    lab = ogAST.Label()
    coord = False
    for child in root.getChildren():
        if child.type == lexer.CIF:
            # Get symbol coordinates
            lab.pos_x, lab.pos_y, lab.width, lab.height = cif(child)
            coord = True
        elif child.type == lexer.ID:
            lab.inputString = get_input_string(child)
            lab.line = child.getLine()
            lab.charPositionInLine = child.getCharPositionInLine()
        elif child.type == lexer.HYPERLINK:
            lab.hyperlink = child.getChild(0).toString()[1:-1]
        else:
            warnings.append(
                    'Unsupported child type in label definition: ' +
                    str(child.type))
    # Report errors with symbol coordinates
    if coord:
        errors = [[e, [lab.pos_x, lab.pos_y]] for e in errors]
        warnings = [[w, [lab.pos_x, lab.pos_y]] for w in warnings]
    return lab, errors, warnings


def pr_file(root):
    ''' Complete PR model - can be made up from several files/strings '''
    errors = []
    warnings = []
    ast = ogAST.AST()
    global DV

    # In case no ASN.1 files are parsed, the DV structure is pre-initialised
    # This to allow SDL types injection in ASN1 ASTs
    DV = type("ASNParseTree", (object, ),
              {"types": {}, "exportedVariables": {}, "asn1Modules": []})

    # Re-order the children of the AST to make sure system and use clauses
    # are parsed before process definition - to get signal definitions
    # and data typess references.
    processes, uses, systems = [], [], []
    for child in root.getChildren():
        ast.pr_files.add(node_filename(child))
        if child.type == lexer.PROCESS:
            processes.append(child)
        elif child.type == lexer.USE:
            uses.append(child)
        elif child.type == lexer.SYSTEM:
            systems.append(child)
        else:
            LOG.error('Unsupported construct in PR:' + str(child.type))
    for child in uses:
        LOG.debug('USE clause')
        # USE clauses can contain a CIF comment with the ASN.1 filename
        use_clause_subs = child.getChildren()
        asn1_filename = None
        for clause in use_clause_subs:
            if clause.type == lexer.ASN1:
                asn1_filename = clause.getChild(0).text[1:-1]
                ast.asn1_filenames.append(asn1_filename)
            else:
                ast.use_clauses.append(clause.text)
#       if not asn1_filename:
#           # Look for case insentitive pr file and add it to AST
#           search = fnmatch.translate(clause.text + '.pr')
#           searchobj = re.compile(search, re.IGNORECASE)
#           for each in os.listdir('.'):
#               if searchobj.match(each):
#                   print 'found', each
        try:
            DV = parse_asn1(tuple(ast.asn1_filenames),
                            ast_version=ASN1.UniqueEnumeratedNames,
                            flags=[ASN1.AstOnly])
            ast.asn1Modules = DV.asn1Modules
            # Add constants defined in the ASN.1 modules (for visibility)
            for mod in ast.asn1Modules:
                ast.asn1_constants.extend(DV.exportedVariables[mod])
        except (ImportError, NameError) as err:
            # Can happen if DataView.py is not there
            LOG.info('USE Clause did not contain ASN.1 filename')
            LOG.debug(str(err))

    for child in systems:
        LOG.debug('found SYSTEM')
        system, err, warn = system_definition(child, parent=ast)
        errors.extend(err)
        warnings.extend(warn)
        ast.systems.append(system)

        def find_processes(block):
            ''' Recursively find processes in a system '''
            try:
                result = [proc for proc in block.processes
                          if not proc.referenced]
            except AttributeError:
                result = []
            for nested in block.blocks:
                result.extend(find_processes(nested))
            return result
        ast.processes.extend(find_processes(system))
    for child in processes:
        # process definition at root level (must be referenced in a system)
        LOG.debug('found PROCESS')
        process, err, warn = process_definition(child, parent=ast)
        ast.processes.append(process)
        process.dataview = types()
        process.asn1Modules = ast.asn1Modules
        errors.extend(err)
        warnings.extend(warn)
    LOG.debug('all files: ' + str(ast.pr_files))

    # Since SDL type declarations are injected in ASN.1 ast,
    # The ASN.1 ASTs needs to be copied at the end of PR parsing process
    # and not just after the ASN1 specific parsing
    ast.dataview = types()
    for mod in DV.exportedVariables:
        ast.asn1_constants.extend(DV.exportedVariables[mod])
    return ast, errors, warnings


def add_to_ast(ast, filename=None, string=None):
    ''' Parse a file or string and add it to an AST '''
    errors, warnings = [], []
    try:
        parser = parser_init(filename=filename, string=string)
    except IOError:
        LOG.error('parser_init failed')
        raise
    # Use Sam & Max output capturer to get errors from ANTLR parser
    with samnmax.capture_ouput() as (stdout, stderr):
        tree_rule_return_scope = parser.pr_file()
    for e in stderr:
        errors.append([e.strip()])
    for w in stdout:
        warnings.append([w.strip()])
    # Root of the AST is of type antlr3.tree.CommonTree
    # Add it as a child of the common tree
    subtree = tree_rule_return_scope.tree
    token_str = parser.getTokenStream()
    children_before = set(ast.children)
    # addChild does not simply add the subtree - it flattens it if necessary
    # this means that possibly SEVERAL subtrees can be added. We must set
    # the token_stream reference to all of them.
    ast.addChild(subtree)
    for tree in set(ast.children) - children_before:
        tree.token_stream = token_str
    return errors, warnings


def parse_pr(files=None, string=None):
    ''' Parse SDL files (.pr) and/or string '''
    warnings = []
    errors = []
    files = files or []
    # define a common tree to combine several PR inputs
    common_tree = antlr3.tree.CommonTree(None)
    for filename in files:
        sys.path.insert(0, os.path.dirname(filename))
    for filename in files:
        err, warn = add_to_ast(common_tree, filename=filename)
        errors.extend(err)
        warnings.extend(warn)
    if string:
        err, warn = add_to_ast(common_tree, string=string)
        errors.extend(err)
        warnings.extend(warn)

    # At the end when common tree is complete, perform the parsing
    og_ast, err, warn = pr_file(common_tree)
    for error in err:
        errors.append([error] if type(error) is not list else error)
    for warning in warn:
        warnings.append([warning] if type(warning) is not list else warning)
    # Post-parsing: additional semantic checks
    # check that all NEXTSTATEs have a correspondingly defined STATE
    # (except the '-' state, which means "stay in the same state')
    for process in og_ast.processes:
        for ns in [t.inputString.lower() for t in process.terminators
                if t.kind == 'next_state']:
            if not ns in [s.lower() for s in
                    process.mapping.viewkeys()] + ['-']:
                errors.append(['State definition missing: ' + ns.upper()])
        # TODO: do the same with JOIN/LABEL
    return og_ast, warnings, errors


def parseSingleElement(elem='', string=''):
    '''
        Parse any symbol and return syntax error and AST entry
        Used for on-the-fly checks when user edits text
        and for copy/cut to create a new object
    '''
    assert(elem in ('input_part', 'output', 'decision', 'alternative_part',
            'terminator_statement', 'label', 'task', 'procedure_call', 'end',
            'text_area', 'state', 'start', 'procedure', 'floating_label',
            'connect_part', 'process_definition', 'proc_start', 'state_start'))
    # Create a dummy context, needed to place context data
    if elem == 'proc_start':
        elem = 'start'
        context = ogAST.Procedure()
    elif elem == 'state_start':
        elem = 'start'
        context = ogAST.CompositeState()
    else:
        context = ogAST.Process()
    LOG.debug('Parsing string: ' + string + ' with elem ' + elem)
    parser = parser_init(string=string)
    parser_ptr = getattr(parser, elem)
    assert parser_ptr is not None
    syntax_errors = []
    semantic_errors = []
    warnings = []
    t = None
    if parser:
        with samnmax.capture_ouput() as (stdout, stderr):
            r = parser_ptr()
        for e in stderr:
            syntax_errors.append(e.strip())
        for w in stdout:
            syntax_errors.append(w.strip())
        # Get the root of the Antlr-AST to build our own AST entry
        root = r.tree
        root.token_stream = parser.getTokenStream()
        backend_ptr = eval(elem)
        try:
            t, semantic_errors, warnings = backend_ptr(
                                root=root, parent=None, context=context)
        except AttributeError as err:
            print str(err)
            print (traceback.format_exc())
            # Syntax checker has no visibility on variables and types
            # so we have to discard exceptions sent by e.g. find_variable
            pass
    return(t, syntax_errors, semantic_errors, warnings,
            context.terminators)


def parser_init(filename=None, string=None):
    ''' Initialize the parser (to be called first) '''
    try:
        char_stream = antlr3.ANTLRFileStream(filename, encoding='utf-8')
    except (IOError, TypeError):
        try:
            char_stream = antlr3.ANTLRStringStream(string)
        except TypeError as err:
            raise IOError('Could not parse input' + str(err))
    lex = lexer.sdl92Lexer(char_stream)
    tokens = antlr3.CommonTokenStream(lex)
    parser = sdl92Parser(tokens)
    return parser


if __name__ == '__main__':
    print 'This module is not callable'