sdlSymbols.py

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

"""
    OpenGEODE - A tiny SDL Editor for TASTE

    This module contains the definition of the SDL symbols,
    including geometry and specific symbol behaviour when needed.

    All symbols inherit the generic Vertical- and Horizontal-
    Symbol classes defined in the "genericSymbols.py" module.

    Copyright (c) 2012-2013 European Space Agency

    Designed and implemented by Maxime Perrotin

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

__all__ = ['Input', 'Output', 'State', 'Task', 'ProcedureCall', 'Label',
           'Decision', 'DecisionAnswer', 'Join', 'Start', 'TextSymbol',
           'Procedure', 'ProcedureStart', 'ProcedureStop', 'ProcessType',
           'StateStart', 'Process', 'ContinuousSignal']

import traceback
import logging
from itertools import chain

from PySide2.QtCore import *
from PySide2.QtGui import *
from PySide2.QtWidgets import *

from .genericSymbols import HorizontalSymbol, VerticalSymbol, Comment
from .Connectors import Connection, JoinConnection, Signalroute

from . import ogParser, ogAST


LOG = logging.getLogger('sdlSymbols')

AST = ogAST.AST()
CONTEXT = ogAST.Process()

# SDL-specific: reserved keywords, to be highlighted in textboxes
# Two kind of formatting are possible: black bold, and red bold
SDL_BLACKBOLD = ['\\b{word}\\b'.format(word=word) for word in (
                'DCL', 'CALL', 'ELSE', 'IF', 'THEN', 'MANTISSA', 'BASE',
                'EXPONENT', 'TRUE', 'FALSE', 'MOD', 'FI', 'WRITE', 'WRITELN',
                'LENGTH', 'PRESENT', 'FPAR', 'TODO', 'FIXME', 'XXX', 'ENDFOR',
                'CHECKME', 'PROCEDURE', 'EXTERNAL', 'IN', 'OUT', 'TIMER',
                'SET_TIMER', 'RESET_TIMER', 'VIA', 'ENTRY', 'EXIT', 'PRIORITY',
                'SYNTYPE', 'ENDSYNTYPE', 'CONSTANTS', 'ENDPROCEDURE', 'FOR',
                'COMMENT', 'SIGNAL', 'SIGNALLIST', 'USE', 'RETURNS', 'ANY',
                'NEWTYPE', 'ENDNEWTYPE', 'ARRAY', 'STRUCT', 'SYNONYM')]

SDL_REDBOLD = ['\\b{word}\\b'.format(word=word) for word in (
              'INPUT', 'OUTPUT', 'STATE', 'DECISION', 'NEXTSTATE', 'INTEGER',
              'CHARACTER', 'ASN1INT',
              'TASK', 'PROCESS', 'LABEL', 'JOIN', 'CONNECTION', 'CONNECT')]


def variables_autocompletion(symbol, type_filter=None):
    ''' Intelligent autocompletion for variables - including struct fields
        Optional: only variables of a type listed in type_filter are kept
    '''
    res = set()
    if not symbol.text:
        return res
    parts = symbol.text.context.split('!')
    if len(parts) == 0:
        return res
    elif len(parts) == 1:
        try:
            fpar = {fp['name']: (fp['type'], None) for fp in CONTEXT.fpar}
        except AttributeError:
            # not in the context of a procedure
            fpar = {}
        # Return the list of variables, possibly filterd by type
        if not type_filter:
            res = set( list(CONTEXT.variables.keys())
                      + list(CONTEXT.global_variables.keys())
                      + list(AST.asn1_constants.keys())
                      + list(fpar.keys()))
        else:
            constants = {name: (cty.type, None)
                         for name, cty in AST.asn1_constants.items()}
            try:
                type_filter_names = [ogParser.type_name(ty)
                                     for ty in type_filter]
            except AttributeError as err:
                # This would need to be investigated: it can happen when
                # using a parameter in an input just after the parameter was
                # added to the signal in the block view, and before any
                # variable has been declared....
                LOG.debug(str(err))
                return res
            for name, (asn1type, _) in chain(CONTEXT.variables.items(),
                                          CONTEXT.global_variables.items(),
                                          constants.items(),
                                          fpar.items()):
                if ogParser.type_name(asn1type) in type_filter_names:
                    res.add(name)
    else:
        var = parts[0].lower()
        try:
            var_t = ogParser.find_variable_type(var, CONTEXT)
            basic = ogParser.find_basic_type(var_t, AST.dataview)
            res = (field.replace('-', '_') for field in basic.Children.keys())
        except (AttributeError, TypeError):
            res = []
        else:
            for each in parts[1:-1]:
                try:
                    for child, childtype in basic.Children.items():
                        if child.lower() == each.lower().replace('_', '-'):
                            basic = ogParser.find_basic_type(childtype.type,
                                                             AST.dataview)
                            break
                    else:
                        res = ()
                        break
                except (AttributeError, TypeError):
                    res = ()
                    break
            else:
                try:
                    res = (field.replace('-', '_')
                           for field in basic.Children.keys())
                except AttributeError:
                    res = ()
    return res




# pylint: disable=R0904
class Input(HorizontalSymbol):
    ''' SDL INPUT Symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = ['Task', 'ProcedureCall', 'Output', 'Decision',
                             'Input', 'Label', 'Connect', 'ContinuousSignal']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']

    common_name = 'input_part'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ''' Create the INPUT symbol '''
        ast = ast or ogAST.Input()
        self.ast = ast
        self.branch_entrypoint = None
        self.width, self.height = 0, 0
        if not ast.pos_y and parent:
            # Make sure the item is placed below its parent
            ast.pos_y = parent.y() + parent.boundingRect().height() + 10
        super(Input, self).__init__(parent,
                                    text=ast.inputString,
                                    x=ast.pos_x or 0,
                                    y=ast.pos_y or 0,
                                    hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        gradient = QRadialGradient(50, 50, 50, 50, 50)
        gradient.setColorAt(0, QColor(255, 240, 170))
        gradient.setColorAt(1, Qt.white)
        self.setBrush(QBrush(gradient))
        self.terminal_symbol = False
        self.parser = ogParser
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    def insert_symbol(self, parent, x, y):
        ''' Insert Input symbol - propagate branch Entry point '''
        # Make sure that parent is a state, not a sibling symbol
        item_parent = (parent if not isinstance(parent, (Input,
                                                         ContinuousSignal))
                       else parent.parentItem())
        self.branch_entrypoint = item_parent.branch_entrypoint
        super(Input, self).insert_symbol(item_parent, x, y)

    def boundingRect(self):
        return QRectF(0, 0, self.width, self.height)


    def set_shape(self, width, height):
        ''' Compute the polygon to fit in width, height '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.lineTo(width, 0)
            path.lineTo(width - 11, height / 2)
            path.lineTo(width, height)
            path.lineTo(0, height)
            path.lineTo(0, 0)
            self.setPath(path)
            super(Input, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        if '(' in str(self):
            # Input parameter: return the list of variables of this type
            input_name = str(self).split('(')[0].strip().lower()
            asn1_filter = [sig.get('type') for sig in CONTEXT.input_signals if
                           sig['name'] == input_name]
            return variables_autocompletion(self, asn1_filter)
        else:
            # Return the list of input signals and timers
            return (set(sig['name'] for sig in CONTEXT.input_signals).union(
                    CONTEXT.global_timers + CONTEXT.timers))


class Connect(Input):
    ''' Connect point below a nested state '''
    common_name = 'connect_part'
    auto_expand = True
    resizeable = False
    # Symbol must not use antialiasing, otherwise the middle line is too thick
    _antialiasing = False

    def set_shape(self, width, height):
        ''' Compute the polygon to fit in width, height '''
        if width != self.width or height != self.height:
            self.setPen(QPen(Qt.blue))
            self.textbox_alignment = Qt.AlignLeft | Qt.AlignTop
            path = QPainterPath()
            path.moveTo(0, 0)
            path.lineTo(0, height)
            #path.moveTo(0, height / 2)
            #path.lineTo(width, height / 2)
            self.setPath(path)
            super(Input, self).set_shape(width, height)

    def resize_item(self, rect):
        ''' Symbol cannot be resized '''
        return

    @property
    def completion_list(self):
        ''' Set auto-completion list: list of exit points of nested state '''
        parent_state = str(self.parentItem()).lower()
        for each in CONTEXT.composite_states:
            if each.statename == parent_state:
                return each.state_exitpoints
        else:
            return set()


# pylint: disable=R0904
class Output(VerticalSymbol):
    ''' SDL OUTPUT Symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = [
            'Task', 'ProcedureCall', 'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    common_name = 'output'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.Output()
        self.ast = ast
        self.width, self.height = 0, 0
        super(Output, self).__init__(parent=parent,
                text=ast.inputString, x=ast.pos_x or 0, y=ast.pos_y or 0,
                hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)

        self.setBrush(QBrush(QColor(255, 255, 202)))
        self.terminal_symbol = False
        self.parser = ogParser
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    def set_shape(self, width, height):
        ''' Compute the polygon to fit in width, height '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.lineTo(width - 11, 0)
            path.lineTo(width, height / 2)
            path.lineTo(width - 11, height)
            path.lineTo(0, height)
            path.lineTo(0, 0)
            self.setPath(path)
            super(Output, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        if '(' in str(self):
            # Output parameter: return the list of variables of this type
            output_name = str(self).split('(')[0].strip().lower()
            asn1_filter = [sig['type'] for sig in CONTEXT.output_signals if
                           hasattr(sig, 'type') and sig['name'] == output_name]
            return variables_autocompletion(self, asn1_filter)
        else:
            # Return the list of output signals
            return (set(sig['name'] for sig in CONTEXT.output_signals))


# pylint: disable=R0904
class Decision(VerticalSymbol):
    ''' SDL DECISION Symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = ['DecisionAnswer', 'Task', 'ProcedureCall',
                             'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    common_name = 'decision'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD + ['\\b{}\\b'.format(word)
                                   for word in ('AND', 'OR')]
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.Decision()
        self.ast = ast
        self.width, self.height = 0, 0
        # Define the point where all branches of the decision can join again
        self.connectionPoint = QPoint(ast.width / 2, ast.height + 30)
        super(Decision, self).__init__(parent, text=ast.inputString,
                x=ast.pos_x or 0, y=ast.pos_y or 0, hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setBrush(QColor(255, 255, 202))
        self.minDistanceToSymbolAbove = 0
        self.parser = ogParser
        self.text_alignment = Qt.AlignHCenter
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    @property
    def terminal_symbol(self):
        '''
            Compute dynamically if the item is terminal by checking
            if all its branches end with a terminator
        '''
        for branch in self.branches():
            if not branch.last_branch_item.terminal_symbol:
                return False
        return True

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        return chain(variables_autocompletion(self), ('length', 'present'))

    def branches(self):
        ''' Return the list of decision answers (as a generator) '''
        return (branch for branch in self.childSymbols()
                if isinstance(branch, DecisionAnswer))

    def set_shape(self, width, height):
        ''' Define polygon points to draw the symbol '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.moveTo(width / 2, 0)
            path.lineTo(width, height / 2)
            path.lineTo(width / 2, height)
            path.lineTo(0, height / 2)
            path.lineTo(width / 2, 0)
            self.setPath(path)
            super(Decision, self).set_shape(width, height)

    def resize_item(self, rect):
        ''' On resize event, make sure connection points are updated '''
        delta_y = self.boundingRect().height() - rect.height()
        super(Decision, self).resize_item(rect)
        self.connectionPoint.setX(self.boundingRect().center().x())
        self.connectionPoint.setY(self.connectionPoint.y() - delta_y)
        self.update_connections()

    def update_connections(self):
        ''' Redefined - update arrows shape below connection point '''
        super(Decision, self).update_connections()
        for branch in self.branches():
            for cnx in branch.last_branch_item.connections():
                cnx.reshape()

    def updateConnectionPointPosition(self):
        ''' Compute the joining point of decision branches '''
        new_y = 0
        new_x = self.boundingRect().width() / 2.0
        answers = False
        for branch in self.branches():
            answers = True
            last_cnx = None
            last = branch.last_branch_item
            try:
                # To compute the branch length, we must keep only the symbols,
                # so we must remove the last connection (if any)
                last_cnx, = (c for c in last.childItems() if
                    isinstance(c, Connection) and not
                    isinstance(c.child, (Comment, HorizontalSymbol)))
                # Don't set parent item to None to avoid Qt segfault
                # The bug with setParentItem is a Qt bug documented here:
                # https://bugreports.qt.io/browse/QTBUG-18616
                # the crash may happen if the scene of the new parent
                # is different from the scene of the object. the doc says
                # it is allowed but an assert in the code makes it crash
                # workaround: first put the item manually in the right scene
                # then call setParentItem
                if self.scene() != last_cnx.scene():
                    self.scene().addItem(last_cnx)
                last_cnx.setParentItem(self)
            except ValueError:
                pass
            branch_len = branch.y() + (
                    branch.boundingRect() |
                    branch.childrenBoundingRect()).height()
            try:
                if last.scene() != last_cnx.scene():
                    last.scene().addItem(last_cnx) # workaround Qt's bug 18616
                last_cnx.setParentItem(last)
            except AttributeError:
                pass
            # If last item was a decision, use its connection point
            # position to get the length of the branch:
            try:
                branch_len = (last.connectionPoint.y() +
                        self.mapFromScene(0, last.scenePos().y()).y())
            except AttributeError:
                pass
            # Rounded with int() -> mandatory when view scale has changed
            new_y = int(max(new_y, branch_len))
        if not answers:
            new_y = int(self.boundingRect().height())
        new_y += 15
        delta = new_y - self.connectionPoint.y()
        self.connectionPoint.setY(new_y)
        self.connectionPoint.setX(new_x)
        if delta != 0:
            child = self.next_aligned_symbol()
            try:
                child.pos_y += delta
            except AttributeError:
                pass
        self.update_connections()


# pylint: disable=R0904
class DecisionAnswer(HorizontalSymbol):
    ''' If Decision is a "switch", DecisionAnswer is a "case" '''
    _insertable_followers = ['DecisionAnswer', 'Task', 'ProcedureCall',
                        'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    common_name = 'alternative_part'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.Answer()
        self.ast = ast
        self.width, self.height = 0, 0 #ast.width, ast.height
        self.terminal_symbol = False
        # last_branch_item is used to compute branch length
        # for the connection point positionning
        self.last_branch_item = self
        super(DecisionAnswer, self).__init__(parent,
                                             text=ast.inputString,
                                             x=ast.pos_x or 0,
                                             y=ast.pos_y or 0,
                                             hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.branch_entrypoint = self
        self.parser = ogParser

    def insert_symbol(self, parent, x, y):
        ''' ANSWER-specific insersion behaviour: link to connection point '''
        if not parent:
            return
        # Make sure that parent is not a sibling answer
        item_parent = (parent if not isinstance(parent, DecisionAnswer)
                       else parent.parentItem())
        super(DecisionAnswer, self).insert_symbol(item_parent, x, y)
        self.last_branch_item.connectionBelow = \
                JoinConnection(self.last_branch_item, item_parent)
        self.text.try_resize()

    def boundingRect(self):
        return QRectF(0, 0, self.width, self.height)

    def set_shape(self, width, height):
        ''' ANSWER has round, disjoint sides - does not fit in a polygon '''
        if width != self.width or height != self.height:
            point = 20
            path = QPainterPath()
            left = QRect(0, 0, point, height)
            right = QRect(width - point, 0, point, height)
            path.arcMoveTo(left, 125)
            path.arcTo(left, 125, 110)
            path.arcMoveTo(right, -55)
            path.arcTo(right, -55, 110)
            path.moveTo(width, height)
            self.setPath(path)
            super(DecisionAnswer, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        return ['ELSE']


# pylint: disable=R0904
class Join(VerticalSymbol):
    ''' JOIN symbol (GOTO) '''
    auto_expand = True
    arrow_head = 'simple'
    common_name = 'terminator_statement'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        self.ast = ast
        self.width, self.height = 0, 0
        if not ast:
            ast = ogAST.Terminator(defName='')
            ast.pos_y = 0
            ast.width = 35
            ast.height = 35
        super(Join, self).__init__(parent,
                                   text=ast.inputString,
                                   x=ast.pos_x,
                                   y=ast.pos_y,
                                   hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setPen(QPen(Qt.blue))
        self.terminal_symbol = True
        self.parser = ogParser

    def resize_item(self, rect):
        ''' Redefinition of the resize item (block is a square) '''
        size = min(rect.width(), rect.height())
        rect.setWidth(size)
        rect.setHeight(size)
        super(Join, self).resize_item(rect)

    def set_shape(self, width, height):
        ''' Define the bouding rectangle of the JOIN symbol '''
        if width != self.width or height != self.height:
            circ = min(width, height)
            path = QPainterPath()
            path.addEllipse(0, 0, circ, circ)
            self.setPath(path)
            super(Join, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list - list of labels '''
        return (label.inputString for label in CONTEXT.labels)

    def update_completion_list(self, pr_text: str) -> None:
        ''' When text was entered, update list of join terminators '''
        ast, _, _, _, _ = self.parser.parseSingleElement(self.common_name,
                                                         pr_text)
        if not ast:
            # in case of syntax error in the symbol text
            return
        for each in (t for t in CONTEXT.terminators if t.kind == 'join'):
            if each.inputString == str(self):
                # Ignore if already defined
                break
        else:
            CONTEXT.terminators.append(ast)


class ProcedureStop(Join):
    ''' Procedure STOP symbol - very similar to JOIN '''
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        self.ast = ast
        self.width, self.height = 0, 0
        if not ast:
            ast = ogAST.Terminator(defName='')
            ast.pos_y = 0
            ast.width = 35
            ast.height = 35
        super(ProcedureStop, self).__init__(parent, ast)

    def set_shape(self, width, height):
        ''' Define the symbol shape '''
        if width != self.width or height != self.height:
            circ = min(width, height)
            path = QPainterPath()
            path.addEllipse(0, 0, circ, circ)
            point1 = path.pointAtPercent(0.625)
            point2 = path.pointAtPercent(0.125)
            point3 = path.pointAtPercent(0.875)
            point4 = path.pointAtPercent(0.375)
            path.moveTo(point1)
            path.lineTo(point2)
            path.moveTo(point3)
            path.lineTo(point4)
            self.setPath(path)
            # call Join superclass, otherwise symbol will take Join shape
            super(Join, self).set_shape(circ, circ)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        try:
            return CONTEXT.state_exitpoints
        except AttributeError:
            # Not in a state but in a procedure
            return set()

    def update_completion_list(self, pr_text):
        ''' When text was entered, if in a nested state update exit points '''
        ast, _, _, _, _ = self.parser.parseSingleElement(self.common_name,
                                                         pr_text)
        if not ast:
            # in case of syntax error in the symbol text
            return
        try:
            CONTEXT.state_exitpoints = \
                    set(CONTEXT.state_exitpoints) | set(str(self))
        except AttributeError:
            # No state exit points in a procedure
            pass


# pylint: disable=R0904
class Label(VerticalSymbol):
    ''' LABEL symbol '''
    _insertable_followers = [
            'Task', 'ProcedureCall', 'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    needs_parent = False
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD
    # Symbol must not use antialiasing, otherwise the middle line is too thick
    _antialiasing = False

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.Label()
        self.ast = ast
        self.width, self.height = 0, 0
        super(Label, self).__init__(parent,
                                    text=ast.inputString,
                                    x=ast.pos_x or 0,
                                    y=ast.pos_y or 0,
                                    hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setPen(QPen(Qt.blue))
        self.terminal_symbol = False
        self.textbox_alignment = Qt.AlignLeft | Qt.AlignTop
        self.parser = ogParser

    @property
    def common_name(self):
        return 'label' if self.hasParent else 'floating_label'

    def set_shape(self, width, height):
        ''' Define the shape of the LABEL symbol '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.addEllipse(0, height / 2, width / 4, height / 2)
            path.moveTo(width / 4, height * 3 / 4)
            path.lineTo(width / 2, height * 3 / 4)
            # Add arrow head
            path.moveTo(width / 2 - 5, height * 3 / 4 - 5)
            path.lineTo(width / 2, height * 3 / 4)
            path.lineTo(width / 2 - 5, height * 3 / 4 + 5)
            # Add vertical line in the middle of the symbol
            path.moveTo(width / 2, 0)
            path.lineTo(width / 2, height)
            # Make sure the bounding rect is withing specifications
            path.moveTo(width, height)
            self.setPath(path)
            super(Label, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list - list of JOIN '''
        return (term.inputString
                for term in CONTEXT.terminators if term.kind == 'join')

    def update_completion_list(self, pr_text):
        ''' When text was entered, update list of labels in current context '''
        ast, _, _, _, _ = self.parser.parseSingleElement(self.common_name,
                                                         pr_text)
        if not ast:
            # in case of syntax error in the symbol text
            return
        for each in CONTEXT.labels:
            if each.inputString == str(self):
                # Ignore if already defined
                break
        else:
            CONTEXT.labels.append(ast)


# pylint: disable=R0904
class Task(VerticalSymbol):
    ''' TASK symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = [
            'Task', 'ProcedureCall', 'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    common_name = 'task'
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ''' Initializes the TASK symbol '''
        ast = ast or ogAST.Task()
        self.ast = ast
        self.width, self.height = 0, 0
        super(Task, self).__init__(parent,
                                   text=ast.inputString,
                                   x=ast.pos_x or 0,
                                   y=ast.pos_y or 0,
                                   hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setBrush(QBrush(QColor(255, 255, 202)))
        self.terminal_symbol = False
        self.parser = ogParser
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    def set_shape(self, width, height):
        ''' Compute the polygon to fit in width, height '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.lineTo(width, 0)
            path.lineTo(width, height)
            path.lineTo(0, height)
            path.lineTo(0, 0)
            self.setPath(path)
            super(Task, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        elems = str(self).lower().strip().split()
        asn1_filter = []
        if len(elems) == 2 and elems[1] == ':=':
            # Find type of variable on the left and filter accordingly
            varname = elems[0]
            try:
                fpar = {fp['name']: (fp['type'], None) for fp in CONTEXT.fpar}
            except AttributeError:
                # not in the context of a procedure
                fpar = {}
            constants = {name: (cty.type, None)
                         for name, cty in AST.asn1_constants.items()}
            for name, (asn1ty, _) in chain (CONTEXT.variables.items(),
                                          CONTEXT.global_variables.items(),
                                          constants.items(),
                                          fpar.items()):
                if name == varname:
                    asn1_filter = [asn1ty]
                    break
        return chain(variables_autocompletion(self, asn1_filter),
                     ogParser.SPECIAL_OPERATORS.keys())

# pylint: disable=R0904
class ProcedureCall(VerticalSymbol):
    ''' PROCEDURE CALL symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = [
            'Task', 'ProcedureCall', 'Output', 'Decision', 'Label']
    _terminal_followers = ['Join', 'State', 'ProcedureStop']
    common_name = 'procedure_call'
    # Define reserved keywords for the syntax highlighter
    blackbold = ['\\bWRITELN\\b', '\\bWRITE\\b',
                 '\\bSET_TIMER\\b', '\\bRESET_TIMER\\b']
    redbold = SDL_REDBOLD

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.Output(defName='')
        self.ast = ast
        self.width, self.height = 0, 0
        super(ProcedureCall, self).__init__(parent,
                                            text=ast.inputString,
                                            x=ast.pos_x or 0,
                                            y=ast.pos_y or 0,
                                            hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setBrush(QBrush(QColor(255, 255, 202)))
        self.terminal_symbol = False
        self.parser = ogParser
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    def set_shape(self, width, height):
        ''' Compute the polygon to fit in width, height '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.addRect(0, 0, width, height)
            path.moveTo(7, 0)
            path.lineTo(7, height)
            path.moveTo(width - 7, 0)
            path.lineTo(width - 7, height)
            self.setPath(path)
            super(ProcedureCall, self).set_shape(width, height)

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        if '(' in str(self):
            # Get the variables of the type of the current parameter
            count = str(self).count(',')
            procname = str(self).split('(')[0].strip().lower()
            for each in (proc for proc in CONTEXT.procedures
                         if proc.inputString.lower() == procname):
                param_types = [p['type'] for p in each.fpar]
                break
            else:
                # Procedure not defined, check special operators
                if (procname == 'set_timer' and count == 1) or (
                        procname == 'reset_timer' and count == 0):
                    return chain(CONTEXT.timers, CONTEXT.global_timers)
                elif procname in ('write', 'writeln'):
                    # Could filter for OCTET STRINGS/Strings/Integer/Booleans
                    return variables_autocompletion(self)
                else:
                    return ()
            if count + 1 > len(param_types):
                # User tries to set more parameters than defined
                return ()
            else:
                # Return variables of the type of the parameter
                asn1_filter = param_types[slice(count, count + 1)]
                return variables_autocompletion(self, asn1_filter)
        else:
            return chain((proc.inputString for proc in CONTEXT.procedures),
                         ('set_timer', 'reset_timer', 'write', 'writeln'))


# pylint: disable=R0904
class TextSymbol(HorizontalSymbol):
    ''' Text symbol - used to declare variables, etc. '''
    common_name = 'text_area'
    default_size = 'any'
    needs_parent = False
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD

    def __init__(self, ast=None):
        ''' Create a Text Symbol '''
        ast = ast or ogAST.TextArea()
        self.ast = ast
        self.width, self.height = 0, 0
        super(TextSymbol, self).__init__(parent=None,
                                         text=ast.inputString,
                                         x=ast.pos_x or 0,
                                         y=ast.pos_y or 0,
                                         hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setBrush(QBrush(QColor(249, 249, 249)))
        self.terminal_symbol = False
        self.position = QPointF(ast.pos_x or 0, ast.pos_y or 0)
        # Disable hyperlinks for Text symbols
        self._no_hyperlink = True
        # Text is not centered in the box - change default alignment:
        self.textbox_alignment = Qt.AlignLeft | Qt.AlignTop
        self.parser = ogParser

    def update_completion_list(self, pr_text):
        ''' When text was entered, update list of variables/FPAR/Timers '''
        # note, on standalone systems, if the textbox contains a
        # USE Dataview comment 'file.asn'. this file is parsed when leaving
        # the textbox. This gives the impression that this function is slow,
        # it it is not! - no need to investigate performance issues here
        # Get AST for the symbol
        ast, _, _, _, _ = self.parser.parseSingleElement('text_area', pr_text)
        if not ast:
            # in case of syntax error in the symbol text
            return
        try:
            CONTEXT.variables.update(ast.variables)
            CONTEXT.timers = list(set(CONTEXT.timers + ast.timers))
        except AttributeError:
            # context may not have variables/timers (eg if context = block)
            pass
        try:
            existing = {proc.inputString.lower()
                       for proc in CONTEXT.procedures}
            CONTEXT.procedures += [proc for proc in ast.procedures
                                   if proc.inputString.lower() not in existing]
            CONTEXT.fpar.extend(ast.fpar)
        except AttributeError:
            pass
        # Update completion list of Signalroutes
        try:
            Signalroute.completion_list |= set(sig['name']
                                               for sig in ast.signals)
            # Here: update input signals of the process AST since the
            # signature of the signals may have changed...TODO
            CONTEXT.signals += ast.signals
        except AttributeError:
            # no AST, e.g. in case of syntax errors in the text area
            pass

    @property
    def completion_list(self):
        ''' Set auto-completion list '''
        try:
            return set(AST.dataview.keys())
        except AttributeError:
            return [] # No Dataview

    def set_shape(self, width, height):
        ''' Define the polygon of the text symbol '''
        if width != self.width or height != self.height:
            path = QPainterPath()
            path.moveTo(width - 10, 0)
            path.lineTo(0, 0)
            path.lineTo(0, height)
            path.lineTo(width, height)
            path.lineTo(width, 10)
            path.lineTo(width - 10, 10)
            path.lineTo(width - 10, 0)
            path.lineTo(width, 10)
            self.setPath(path)
            super(TextSymbol, self).set_shape(width, height)

    def resize_item(self, rect):
        ''' Text Symbol only resizes down or right '''
        if self.grabber.resize_mode.endswith('left'):
            return
        self.prepareGeometryChange()
        self.set_shape(rect.width(), rect.height())


# pylint: disable=R0904
class State(VerticalSymbol):
    ''' SDL STATE Symbol '''
    _unique_followers = ['Comment']
    _insertable_followers = ['Input', 'Connect', 'ContinuousSignal']
    arrow_head = 'simple'
    common_name = 'terminator_statement'
    needs_parent = False
    # Define reserved keywords for the syntax highlighter
    blackbold = SDL_BLACKBOLD
    redbold = SDL_REDBOLD
    context_name = "state"

    def __init__(self, parent=None, ast=None):
        ast = ast or ogAST.State()
        self.ast = ast
        self.width, self.height = 0, 0
        ast.inputString = getattr(ast, 'via', None) or ast.inputString
        super(State, self).__init__(parent=parent,
                                    text=ast.inputString,
                                    x=ast.pos_x or 0,
                                    y=ast.pos_y or 0,
                                    hyperlink=ast.hyperlink)
        self.set_shape(ast.width, ast.height)
        self.setBrush(QBrush(QColor(255, 228, 213)))
        self.terminal_symbol = True
        if parent:
            try:
                # Map AST scene coordinates to get actual position
                self.position += self.mapFromScene(ast.pos_x or 0,
                                                   ast.pos_y or 0)
            except TypeError:
                self.update_position()
        else:
            # Use scene coordinates to position
            self.position = QPointF(ast.pos_x or 0, ast.pos_y or 0)
        self.parser = ogParser
        if ast.comment:
            Comment(parent=self, ast=ast.comment)

    @property
    def allow_nesting(self):
        ''' Redefinition - must be checked according to context '''
        result = not any(elem in str(self).lower().strip()
                       for elem in ('-', ',', '*'))
        return result

    @property
    def nested_scene(self):
        ''' Redefined - nested scene per state must be unique '''
        return self._nested_scene

    def double_click(self):
        ''' Catch a double click - Set nested scene '''
        for each, value in self.scene().composite_states.items():
            if str(self).split()[0].lower() == str(each):
                self.nested_scene = value
                break
        else:
            self.nested_scene = None

    @nested_scene.setter
    def nested_scene(self, value):
        ''' Set the value of the nested scene '''
        self._nested_scene = value

    def update_completion_list(self, pr_text):