Backend template

GenericBackend.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+    OpenGEODE - A tiny SDL Editor for TASTE
+
+    This module is a template for backends such as code generators
+
+    Entry point:
+    The AST of the model that is parsed is described in ogAST.py
+
+    A Visitor Pattern using Python's "singledispatch" mechanism is used
+    to go through the AST and generate code for each SDL construct.
+
+    There is a single function called "generate", decorated with the
+    singledispatch mechanism, that needs to be called to generate the code
+    of any AST element.
+
+    Copyright (c) 2012-2014 European Space Agency
+
+    Designed and implemented by Maxime Perrotin
+
+    Contact: maxime.perrotin@esa.int
+"""
+
+
+import logging
+from singledispatch import singledispatch
+
+import ogAST
+
+LOG = logging.getLogger(__name__)
+
+__all__ = ['generate']
+
+
+@singledispatch
+def generate(ast):
+    ''' Generate the code for an item of the AST '''
+    raise TypeError('[Backend] Unsupported AST construct')
+
+# Processing of the AST
+
+@generate.register(ogAST.Process)
+def _process(process):
+    ''' Generate the code for a complete process (AST Top level) '''
+    pass
+
+def write_statement(param, newline):
+    ''' Generate the code for the special "write" operator '''
+    pass
+
+@generate.register(ogAST.Output)
+@generate.register(ogAST.ProcedureCall)
+def _call_external_function(output):
+    ''' Generate the code of a set of output or procedure call statement '''
+    pass
+
+
+@generate.register(ogAST.TaskAssign)
+def _task_assign(task):
+    ''' A list of assignments in a task symbol '''
+    pass
+
+
+@generate.register(ogAST.TaskInformalText)
+def _task_informal_text(task):
+    ''' Generate comments for informal text '''
+    pass
+
+
+@generate.register(ogAST.TaskForLoop)
+def _task_forloop(task):
+    '''
+        Return the code corresponding to a for loop. Two forms are possible:
+        for x in range ([start], stop [, step])
+        for x in iterable (a SEQUENCE OF)
+    '''
+    pass
+
+
+@generate.register(ogAST.PrimVariable)
+def _primary_variable(prim):
+    ''' Single variable reference '''
+    pass
+
+
+@generate.register(ogAST.PrimPath)
+def _prim_path(primaryId):
+    '''
+        Return the string of an element list (path)
+        cases: a => 'l_a' (reference to a variable)
+        a_timer => 'a_timer'  (reference to a timer)
+        a!b => a.b (field of a structure)
+        a!b if a is a CHOICE => TypeOfa_b_get(a)
+        a(Expression) => a(ExpressionSolver) (array index)
+        Expression can be complex (if-then-else-fi..)
+    '''
+    pass
+
+
+@generate.register(ogAST.ExprPlus)
+@generate.register(ogAST.ExprMul)
+@generate.register(ogAST.ExprMinus)
+@generate.register(ogAST.ExprEq)
+@generate.register(ogAST.ExprNeq)
+@generate.register(ogAST.ExprGt)
+@generate.register(ogAST.ExprGe)
+@generate.register(ogAST.ExprLt)
+@generate.register(ogAST.ExprLe)
+@generate.register(ogAST.ExprDiv)
+@generate.register(ogAST.ExprMod)
+@generate.register(ogAST.ExprRem)
+@generate.register(ogAST.ExprAssign)
+def _basic_operators(expr):
+    ''' Expressions with two sides '''
+    pass
+
+
+@generate.register(ogAST.ExprOr)
+@generate.register(ogAST.ExprAnd)
+@generate.register(ogAST.ExprXor)
+def _bitwise_operators(expr):
+    ''' Logical operators '''
+    pass
+
+
+@generate.register(ogAST.ExprAppend)
+def _append(expr):
+    ''' Generate code for the APPEND construct: a // b '''
+    pass
+
+
+@generate.register(ogAST.ExprIn)
+def _expr_in(expr):
+    ''' IN expressions: check if item is in a SEQUENCE OF '''
+    pass
+
+
+@generate.register(ogAST.PrimEnumeratedValue)
+def _enumerated_value(primary):
+    ''' Generate code for an enumerated value '''
+    pass
+
+
+@generate.register(ogAST.PrimChoiceDeterminant)
+def _choice_determinant(primary):
+    ''' Generate code for a choice determinant (enumerated) '''
+    pass
+
+
+@generate.register(ogAST.PrimInteger)
+@generate.register(ogAST.PrimReal)
+@generate.register(ogAST.PrimBoolean)
+def _integer(primary):
+    ''' Generate code for a raw integer/real/boolean value  '''
+    pass
+
+
+@generate.register(ogAST.PrimEmptyString)
+def _empty_string(primary):
+    ''' Generate code for an empty SEQUENCE OF: {} '''
+    pass
+
+
+@generate.register(ogAST.PrimStringLiteral)
+def _string_literal(primary):
+    ''' Generate code for a string (Octet String) '''
+    pass
+
+
+@generate.register(ogAST.PrimConstant)
+def _constant(primary):
+    ''' Generate code for a reference to an ASN.1 constant '''
+    pass
+
+
+@generate.register(ogAST.PrimMantissaBaseExp)
+def _mantissa_base_exp(primary):
+    ''' Generate code for a Real with Mantissa-base-Exponent representation '''
+    pass
+
+
+@generate.register(ogAST.PrimIfThenElse)
+def _if_then_else(ifThenElse):
+    ''' Return string and statements for ternary operator '''
+    pass
+
+
+@generate.register(ogAST.PrimSequence)
+def _sequence(seq):
+    ''' Return Ada string for an ASN.1 SEQUENCE '''
+    pass
+
+
+@generate.register(ogAST.PrimSequenceOf)
+def _sequence_of(seqof):
+    ''' Return Ada string for an ASN.1 SEQUENCE OF '''
+    pass
+
+
+@generate.register(ogAST.PrimChoiceItem)
+def _choiceitem(choice):
+    ''' Return the Ada code for a CHOICE expression '''
+    pass
+
+
+@generate.register(ogAST.Decision)
+def _decision(dec):
+    ''' generate the code for a decision '''
+    pass
+
+
+@generate.register(ogAST.Label)
+def _label(tr):
+    ''' Transition following labels are generated in a separate section
+        for visibility reasons (see Ada scope)
+    '''
+    pass
+
+
+@generate.register(ogAST.Transition)
+def _transition(tr):
+    ''' generate the code for a transition '''
+    pass
+
+
+@generate.register(ogAST.Floating_label)
+def _floating_label(label):
+    ''' Generate the code for a floating label (Ada label + transition) '''
+    pass
+
+
+@generate.register(ogAST.Procedure)
+def _inner_procedure(proc):
+    ''' Generate the code for a procedure '''
+    pass