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c_parser.py
#------------------------------------------------------------------------------ # pycparser: c_parser.py # # CParser class: Parser and AST builder for the C language # # Copyright (C) 2008-2015, Eli Bendersky # License: BSD #------------------------------------------------------------------------------ import re from ply import yacc from . import c_ast from .c_lexer import CLexer from .plyparser import PLYParser, Coord, ParseError from .ast_transforms import fix_switch_cases class CParser(PLYParser): def __init__( self, lex_optimize=True, lextab='pycparser.lextab', yacc_optimize=True, yacctab='pycparser.yacctab', yacc_debug=False, taboutputdir=''): """ Create a new CParser. Some arguments for controlling the debug/optimization level of the parser are provided. The defaults are tuned for release/performance mode. The simple rules for using them are: *) When tweaking CParser/CLexer, set these to False *) When releasing a stable parser, set to True lex_optimize: Set to False when you're modifying the lexer. Otherwise, changes in the lexer won't be used, if some lextab.py file exists. When releasing with a stable lexer, set to True to save the re-generation of the lexer table on each run. lextab: Points to the lex table that's used for optimized mode. Only if you're modifying the lexer and want some tests to avoid re-generating the table, make this point to a local lex table file (that's been earlier generated with lex_optimize=True) yacc_optimize: Set to False when you're modifying the parser. Otherwise, changes in the parser won't be used, if some parsetab.py file exists. When releasing with a stable parser, set to True to save the re-generation of the parser table on each run. yacctab: Points to the yacc table that's used for optimized mode. Only if you're modifying the parser, make this point to a local yacc table file yacc_debug: Generate a parser.out file that explains how yacc built the parsing table from the grammar. taboutputdir: Set this parameter to control the location of generated lextab and yacctab files. """ self.clex = CLexer( error_func=self._lex_error_func, on_lbrace_func=self._lex_on_lbrace_func, on_rbrace_func=self._lex_on_rbrace_func, type_lookup_func=self._lex_type_lookup_func) self.clex.build( optimize=lex_optimize, lextab=lextab, outputdir=taboutputdir) self.tokens = self.clex.tokens rules_with_opt = [ 'abstract_declarator', 'assignment_expression', 'declaration_list', 'declaration_specifiers', 'designation', 'expression', 'identifier_list', 'init_declarator_list', 'initializer_list', 'parameter_type_list', 'specifier_qualifier_list', 'block_item_list', 'type_qualifier_list', 'struct_declarator_list' ] for rule in rules_with_opt: self._create_opt_rule(rule) self.cparser = yacc.yacc( module=self, start='translation_unit_or_empty', debug=yacc_debug, optimize=yacc_optimize, tabmodule=yacctab, outputdir=taboutputdir) # Stack of scopes for keeping track of symbols. _scope_stack[-1] is # the current (topmost) scope. Each scope is a dictionary that # specifies whether a name is a type. If _scope_stack[n][name] is # True, 'name' is currently a type in the scope. If it's False, # 'name' is used in the scope but not as a type (for instance, if we # saw: int name; # If 'name' is not a key in _scope_stack[n] then 'name' was not defined # in this scope at all. self._scope_stack = [dict()] # Keeps track of the last token given to yacc (the lookahead token) self._last_yielded_token = None def parse(self, text, filename='', debuglevel=0): """ Parses C code and returns an AST. text: A string containing the C source code filename: Name of the file being parsed (for meaningful error messages) debuglevel: Debug level to yacc """ self.clex.filename = filename self.clex.reset_lineno() self._scope_stack = [dict()] self._last_yielded_token = None return self.cparser.parse( input=text, lexer=self.clex, debug=debuglevel) ######################-- PRIVATE --###################### def _push_scope(self): self._scope_stack.append(dict()) def _pop_scope(self): assert len(self._scope_stack) > 1 self._scope_stack.pop() def _add_typedef_name(self, name, coord): """ Add a new typedef name (ie a TYPEID) to the current scope """ if not self._scope_stack[-1].get(name, True): self._parse_error( "Typedef %r previously declared as non-typedef " "in this scope" % name, coord) self._scope_stack[-1][name] = True def _add_identifier(self, name, coord): """ Add a new object, function, or enum member name (ie an ID) to the current scope """ if self._scope_stack[-1].get(name, False): self._parse_error( "Non-typedef %r previously declared as typedef " "in this scope" % name, coord) self._scope_stack[-1][name] = False def _is_type_in_scope(self, name): """ Is *name* a typedef-name in the current scope? """ for scope in reversed(self._scope_stack): # If name is an identifier in this scope it shadows typedefs in # higher scopes. in_scope = scope.get(name) if in_scope is not None: return in_scope return False def _lex_error_func(self, msg, line, column): self._parse_error(msg, self._coord(line, column)) def _lex_on_lbrace_func(self): self._push_scope() def _lex_on_rbrace_func(self): self._pop_scope() def _lex_type_lookup_func(self, name): """ Looks up types that were previously defined with typedef. Passed to the lexer for recognizing identifiers that are types. """ is_type = self._is_type_in_scope(name) return is_type def _get_yacc_lookahead_token(self): """ We need access to yacc's lookahead token in certain cases. This is the last token yacc requested from the lexer, so we ask the lexer. """ return self.clex.last_token # To understand what's going on here, read sections A.8.5 and # A.8.6 of K&R2 very carefully. # # A C type consists of a basic type declaration, with a list # of modifiers. For example: # # int *c[5]; # # The basic declaration here is 'int c', and the pointer and # the array are the modifiers. # # Basic declarations are represented by TypeDecl (from module c_ast) and the # modifiers are FuncDecl, PtrDecl and ArrayDecl. # # The standard states that whenever a new modifier is parsed, it should be # added to the end of the list of modifiers. For example: # # K&R2 A.8.6.2: Array Declarators # # In a declaration T D where D has the form # D1 [constant-expression-opt] # and the type of the identifier in the declaration T D1 is # "type-modifier T", the type of the # identifier of D is "type-modifier array of T" # # This is what this method does. The declarator it receives # can be a list of declarators ending with TypeDecl. It # tacks the modifier to the end of this list, just before # the TypeDecl. # # Additionally, the modifier may be a list itself. This is # useful for pointers, that can come as a chain from the rule # p_pointer. In this case, the whole modifier list is spliced # into the new location. def _type_modify_decl(self, decl, modifier): """ Tacks a type modifier on a declarator, and returns the modified declarator. Note: the declarator and modifier may be modified """ #~ print '****' #~ decl.show(offset=3) #~ modifier.show(offset=3) #~ print '****' modifier_head = modifier modifier_tail = modifier # The modifier may be a nested list. Reach its tail. # while modifier_tail.type: modifier_tail = modifier_tail.type # If the decl is a basic type, just tack the modifier onto # it # if isinstance(decl, c_ast.TypeDecl): modifier_tail.type = decl return modifier else: # Otherwise, the decl is a list of modifiers. Reach # its tail and splice the modifier onto the tail, # pointing to the underlying basic type. # decl_tail = decl while not isinstance(decl_tail.type, c_ast.TypeDecl): decl_tail = decl_tail.type modifier_tail.type = decl_tail.type decl_tail.type = modifier_head return decl # Due to the order in which declarators are constructed, # they have to be fixed in order to look like a normal AST. # # When a declaration arrives from syntax construction, it has # these problems: # * The innermost TypeDecl has no type (because the basic # type is only known at the uppermost declaration level) # * The declaration has no variable name, since that is saved # in the innermost TypeDecl # * The typename of the declaration is a list of type # specifiers, and not a node. Here, basic identifier types # should be separated from more complex types like enums # and structs. # # This method fixes these problems. # def _fix_decl_name_type(self, decl, typename): """ Fixes a declaration. Modifies decl. """ # Reach the underlying basic type # type = decl while not isinstance(type, c_ast.TypeDecl): type = type.type decl.name = type.declname type.quals = decl.quals # The typename is a list of types. If any type in this # list isn't an IdentifierType, it must be the only # type in the list (it's illegal to declare "int enum ..") # If all the types are basic, they're collected in the # IdentifierType holder. # for tn in typename: if not isinstance(tn, c_ast.IdentifierType): if len(typename) > 1: self._parse_error( "Invalid multiple types specified", tn.coord) else: type.type = tn return decl if not typename: # Functions default to returning int # if not isinstance(decl.type, c_ast.FuncDecl): self._parse_error( "Missing type in declaration", decl.coord) type.type = c_ast.IdentifierType( ['int'], coord=decl.coord) else: # At this point, we know that typename is a list of IdentifierType # nodes. Concatenate all the names into a single list. # type.type = c_ast.IdentifierType( [name for id in typename for name in id.names], coord=typename[0].coord) return decl def _add_declaration_specifier(self, declspec, newspec, kind): """ Declaration specifiers are represented by a dictionary with the entries: * qual: a list of type qualifiers * storage: a list of storage type qualifiers * type: a list of type specifiers * function: a list of function specifiers This method is given a declaration specifier, and a new specifier of a given kind. Returns the declaration specifier, with the new specifier incorporated. """ spec = declspec or dict(qual=[], storage=[], type=[], function=[]) spec[kind].insert(0, newspec) return spec def _build_declarations(self, spec, decls, typedef_namespace=False): """ Builds a list of declarations all sharing the given specifiers. If typedef_namespace is true, each declared name is added to the "typedef namespace", which also includes objects, functions, and enum constants. """ is_typedef = 'typedef' in spec['storage'] declarations = [] # Bit-fields are allowed to be unnamed. # if decls[0].get('bitsize') is not None: pass # When redeclaring typedef names as identifiers in inner scopes, a # problem can occur where the identifier gets grouped into # spec['type'], leaving decl as None. This can only occur for the # first declarator. # elif decls[0]['decl'] is None: if len(spec['type']) < 2 or len(spec['type'][-1].names) != 1 or \ not self._is_type_in_scope(spec['type'][-1].names[0]): coord = '?' for t in spec['type']: if hasattr(t, 'coord'): coord = t.coord break self._parse_error('Invalid declaration', coord) # Make this look as if it came from "direct_declarator:ID" decls[0]['decl'] = c_ast.TypeDecl( declname=spec['type'][-1].names[0], type=None, quals=None, coord=spec['type'][-1].coord) # Remove the "new" type's name from the end of spec['type'] del spec['type'][-1] # A similar problem can occur where the declaration ends up looking # like an abstract declarator. Give it a name if this is the case. # elif not isinstance(decls[0]['decl'], (c_ast.Struct, c_ast.Union, c_ast.IdentifierType)): decls_0_tail = decls[0]['decl'] while not isinstance(decls_0_tail, c_ast.TypeDecl): decls_0_tail = decls_0_tail.type if decls_0_tail.declname is None: decls_0_tail.declname = spec['type'][-1].names[0] del spec['type'][-1] for decl in decls: assert decl['decl'] is not None if is_typedef: declaration = c_ast.Typedef( name=None, quals=spec['qual'], storage=spec['storage'], type=decl['decl'], coord=decl['decl'].coord) else: declaration = c_ast.Decl( name=None, quals=spec['qual'], storage=spec['storage'], funcspec=spec['function'], type=decl['decl'], init=decl.get('init'), bitsize=decl.get('bitsize'), coord=decl['decl'].coord) if isinstance(declaration.type, (c_ast.Struct, c_ast.Union, c_ast.IdentifierType)): fixed_decl = declaration else: fixed_decl = self._fix_decl_name_type(declaration, spec['type']) # Add the type name defined by typedef to a # symbol table (for usage in the lexer) # if typedef_namespace: if is_typedef: self._add_typedef_name(fixed_decl.name, fixed_decl.coord) else: self._add_identifier(fixed_decl.name, fixed_decl.coord) declarations.append(fixed_decl) return declarations def _build_function_definition(self, spec, decl, param_decls, body): """ Builds a function definition. """ assert 'typedef' not in spec['storage'] declaration = self._build_declarations( spec=spec, decls=[dict(decl=decl, init=None)], typedef_namespace=True)[0] return c_ast.FuncDef( decl=declaration, param_decls=param_decls, body=body, coord=decl.coord) def _select_struct_union_class(self, token): """ Given a token (either STRUCT or UNION), selects the appropriate AST class. """ if token == 'struct': return c_ast.Struct else: return c_ast.Union ## ## Precedence and associativity of operators ## precedence = ( ('left', 'LOR'), ('left', 'LAND'), ('left', 'OR'), ('left', 'XOR'), ('left', 'AND'), ('left', 'EQ', 'NE'), ('left', 'GT', 'GE', 'LT', 'LE'), ('left', 'RSHIFT', 'LSHIFT'), ('left', 'PLUS', 'MINUS'), ('left', 'TIMES', 'DIVIDE', 'MOD') ) ## ## Grammar productions ## Implementation of the BNF defined in K&R2 A.13 ## # Wrapper around a translation unit, to allow for empty input. # Not strictly part of the C99 Grammar, but useful in practice. # def p_translation_unit_or_empty(self, p): """ translation_unit_or_empty : translation_unit | empty """ if p[1] is None: p[0] = c_ast.FileAST([]) else: p[0] = c_ast.FileAST(p[1]) def p_translation_unit_1(self, p): """ translation_unit : external_declaration """ # Note: external_declaration is already a list # p[0] = p[1] def p_translation_unit_2(self, p): """ translation_unit : translation_unit external_declaration """ if p[2] is not None: p[1].extend(p[2]) p[0] = p[1] # Declarations always come as lists (because they can be # several in one line), so we wrap the function definition # into a list as well, to make the return value of # external_declaration homogenous. # def p_external_declaration_1(self, p): """ external_declaration : function_definition """ p[0] = [p[1]] def p_external_declaration_2(self, p): """ external_declaration : declaration """ p[0] = p[1] def p_external_declaration_3(self, p): """ external_declaration : pp_directive """ p[0] = p[1] def p_external_declaration_4(self, p): """ external_declaration : SEMI """ p[0] = None def p_pp_directive(self, p): """ pp_directive : PPHASH """ self._parse_error('Directives not supported yet', self._coord(p.lineno(1))) # In function definitions, the declarator can be followed by # a declaration list, for old "K&R style" function definitios. # def p_function_definition_1(self, p): """ function_definition : declarator declaration_list_opt compound_statement """ # no declaration specifiers - 'int' becomes the default type spec = dict( qual=[], storage=[], type=[c_ast.IdentifierType(['int'], coord=self._coord(p.lineno(1)))], function=[]) p[0] = self._build_function_definition( spec=spec, decl=p[1], param_decls=p[2], body=p[3]) def p_function_definition_2(self, p): """ function_definition : declaration_specifiers declarator declaration_list_opt compound_statement """ spec = p[1] p[0] = self._build_function_definition( spec=spec, decl=p[2], param_decls=p[3], body=p[4]) def p_statement(self, p): """ statement : labeled_statement | expression_statement | compound_statement | selection_statement | iteration_statement | jump_statement """ p[0] = p[1] # In C, declarations can come several in a line: # int x, *px, romulo = 5; # # However, for the AST, we will split them to separate Decl # nodes. # # This rule splits its declarations and always returns a list # of Decl nodes, even if it's one element long. # def p_decl_body(self, p): """ decl_body : declaration_specifiers init_declarator_list_opt """ spec = p[1] # p[2] (init_declarator_list_opt) is either a list or None # if p[2] is None: # By the standard, you must have at least one declarator unless # declaring a structure tag, a union tag, or the members of an # enumeration. # ty = spec['type'] s_u_or_e = (c_ast.Struct, c_ast.Union, c_ast.Enum) if len(ty) == 1 and isinstance(ty[0], s_u_or_e): decls = [c_ast.Decl( name=None, quals=spec['qual'], storage=spec['storage'], funcspec=spec['function'], type=ty[0], init=None, bitsize=None, coord=ty[0].coord)] # However, this case can also occur on redeclared identifiers in # an inner scope. The trouble is that the redeclared type's name # gets grouped into declaration_specifiers; _build_declarations # compensates for this. # else: decls = self._build_declarations( spec=spec, decls=[dict(decl=None, init=None)], typedef_namespace=True) else: decls = self._build_declarations( spec=spec, decls=p[2], typedef_namespace=True) p[0] = decls # The declaration has been split to a decl_body sub-rule and # SEMI, because having them in a single rule created a problem # for defining typedefs. # # If a typedef line was directly followed by a line using the # type defined with the typedef, the type would not be # recognized. This is because to reduce the declaration rule, # the parser's lookahead asked for the token after SEMI, which # was the type from the next line, and the lexer had no chance # to see the updated type symbol table. # # Splitting solves this problem, because after seeing SEMI, # the parser reduces decl_body, which actually adds the new # type into the table to be seen by the lexer before the next # line is reached. def p_declaration(self, p): """ declaration : decl_body SEMI """ p[0] = p[1] # Since each declaration is a list of declarations, this # rule will combine all the declarations and return a single # list # def p_declaration_list(self, p): """ declaration_list : declaration | declaration_list declaration """ p[0] = p[1] if len(p) == 2 else p[1] + p[2] def p_declaration_specifiers_1(self, p): """ declaration_specifiers : type_qualifier declaration_specifiers_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'qual') def p_declaration_specifiers_2(self, p): """ declaration_specifiers : type_specifier declaration_specifiers_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'type') def p_declaration_specifiers_3(self, p): """ declaration_specifiers : storage_class_specifier declaration_specifiers_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'storage') def p_declaration_specifiers_4(self, p): """ declaration_specifiers : function_specifier declaration_specifiers_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'function') def p_storage_class_specifier(self, p): """ storage_class_specifier : AUTO | REGISTER | STATIC | EXTERN | TYPEDEF """ p[0] = p[1] def p_function_specifier(self, p): """ function_specifier : INLINE """ p[0] = p[1] def p_type_specifier_1(self, p): """ type_specifier : VOID | _BOOL | CHAR | SHORT | INT | LONG | FLOAT | DOUBLE | _COMPLEX | SIGNED | UNSIGNED """ p[0] = c_ast.IdentifierType([p[1]], coord=self._coord(p.lineno(1))) def p_type_specifier_2(self, p): """ type_specifier : typedef_name | enum_specifier | struct_or_union_specifier """ p[0] = p[1] def p_type_qualifier(self, p): """ type_qualifier : CONST | RESTRICT | VOLATILE """ p[0] = p[1] def p_init_declarator_list_1(self, p): """ init_declarator_list : init_declarator | init_declarator_list COMMA init_declarator """ p[0] = p[1] + [p[3]] if len(p) == 4 else [p[1]] # If the code is declaring a variable that was declared a typedef in an # outer scope, yacc will think the name is part of declaration_specifiers, # not init_declarator, and will then get confused by EQUALS. Pass None # up in place of declarator, and handle this at a higher level. # def p_init_declarator_list_2(self, p): """ init_declarator_list : EQUALS initializer """ p[0] = [dict(decl=None, init=p[2])] # Similarly, if the code contains duplicate typedefs of, for example, # array types, the array portion will appear as an abstract declarator. # def p_init_declarator_list_3(self, p): """ init_declarator_list : abstract_declarator """ p[0] = [dict(decl=p[1], init=None)] # Returns a {decl=<declarator> : init=<initializer>} dictionary # If there's no initializer, uses None # def p_init_declarator(self, p): """ init_declarator : declarator | declarator EQUALS initializer """ p[0] = dict(decl=p[1], init=(p[3] if len(p) > 2 else None)) def p_specifier_qualifier_list_1(self, p): """ specifier_qualifier_list : type_qualifier specifier_qualifier_list_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'qual') def p_specifier_qualifier_list_2(self, p): """ specifier_qualifier_list : type_specifier specifier_qualifier_list_opt """ p[0] = self._add_declaration_specifier(p[2], p[1], 'type') # TYPEID is allowed here (and in other struct/enum related tag names), because # struct/enum tags reside in their own namespace and can be named the same as types # def p_struct_or_union_specifier_1(self, p): """ struct_or_union_specifier : struct_or_union ID | struct_or_union TYPEID """ klass = self._select_struct_union_class(p[1]) p[0] = klass( name=p[2], decls=None, coord=self._coord(p.lineno(2))) def p_struct_or_union_specifier_2(self, p): """ struct_or_union_specifier : struct_or_union brace_open struct_declaration_list brace_close """ klass = self._select_struct_union_class(p[1]) p[0] = klass( name=None, decls=p[3], coord=self._coord(p.lineno(2))) def p_struct_or_union_specifier_3(self, p): """ struct_or_union_specifier : struct_or_union ID brace_open struct_declaration_list brace_close | struct_or_union TYPEID brace_open struct_declaration_list brace_close """ klass = self._select_struct_union_class(p[1]) p[0] = klass( name=p[2], decls=p[4], coord=self._coord(p.lineno(2))) def p_struct_or_union(self, p): """ struct_or_union : STRUCT | UNION """ p[0] = p[1] # Combine all declarations into a single list # def p_struct_declaration_list(self, p): """ struct_declaration_list : struct_declaration | struct_declaration_list struct_declaration """ p[0] = p[1] if len(p) == 2 else p[1] + p[2] def p_struct_declaration_1(self, p): """ struct_declaration : specifier_qualifier_list struct_declarator_list_opt SEMI """ spec = p[1] assert 'typedef' not in spec['storage'] if p[2] is not None: decls = self._build_declarations( spec=spec, decls=p[2]) elif len(spec['type']) == 1: # Anonymous struct/union, gcc extension, C1x feature. # Although the standard only allows structs/unions here, I see no # reason to disallow other types since some compilers have typedefs # here, and pycparser isn't about rejecting all invalid code. # node = spec['type'][0] if isinstance(node, c_ast.Node): decl_type = node else: decl_type = c_ast.IdentifierType(node) decls = self._build_declarations( spec=spec, decls=[dict(decl=decl_type)]) else: # Structure/union members can have the same names as typedefs. # The trouble is that the member's name gets grouped into # specifier_qualifier_list; _build_declarations compensates. # decls = self._build_declarations( spec=spec, decls=[dict(decl=None, init=None)]) p[0] = decls def p_struct_declaration_2(self, p): """ struct_declaration : specifier_qualifier_list abstract_declarator SEMI """ # "Abstract declarator?!", you ask? Structure members can have the # same names as typedefs. The trouble is that the member's name gets # grouped into specifier_qualifier_list, leaving any remainder to # appear as an abstract declarator, as in: # typedef int Foo; # struct { Foo Foo[3]; }; # p[0] = self._build_declarations( spec=p[1], decls=[dict(decl=p[2], init=None)]) def p_struct_declarator_list(self, p): """ struct_declarator_list : struct_declarator | struct_declarator_list COMMA struct_declarator """ p[0] = p[1] + [p[3]] if len(p) == 4 else [p[1]] # struct_declarator passes up a dict with the keys: decl (for # the underlying declarator) and bitsize (for the bitsize) # def p_struct_declarator_1(self, p): """ struct_declarator : declarator """ p[0] = {'decl': p[1], 'bitsize': None} def p_struct_declarator_2(self, p): """ struct_declarator : declarator COLON constant_expression | COLON constant_expression """ if len(p) > 3: p[0] = {'decl': p[1], 'bitsize': p[3]} else: p[0] = {'decl': c_ast.TypeDecl(None, None, None), 'bitsize': p[2]} def p_enum_specifier_1(self, p): """ enum_specifier : ENUM ID | ENUM TYPEID """ p[0] = c_ast.Enum(p[2], None, self._coord(p.lineno(1))) def p_enum_specifier_2(self, p): """ enum_specifier : ENUM brace_open enumerator_list brace_close """ p[0] = c_ast.Enum(None, p[3], self._coord(p.lineno(1))) def p_enum_specifier_3(self, p): """ enum_specifier : ENUM ID brace_open enumerator_list brace_close | ENUM TYPEID brace_open enumerator_list brace_close """ p[0] = c_ast.Enum(p[2], p[4], self._coord(p.lineno(1))) def p_enumerator_list(self, p): """ enumerator_list : enumerator | enumerator_list COMMA | enumerator_list COMMA enumerator """ if len(p) == 2: p[0] = c_ast.EnumeratorList([p[1]], p[1].coord) elif len(p) == 3: p[0] = p[1] else: p[1].enumerators.append(p[3]) p[0] = p[1] def p_enumerator(self, p): """ enumerator : ID | ID EQUALS constant_expression """ if len(p) == 2: enumerator = c_ast.Enumerator( p[1], None, self._coord(p.lineno(1))) else: enumerator = c_ast.Enumerator( p[1], p[3], self._coord(p.lineno(1))) self._add_identifier(enumerator.name, enumerator.coord) p[0] = enumerator def p_declarator_1(self, p): """ declarator : direct_declarator """ p[0] = p[1] def p_declarator_2(self, p): """ declarator : pointer direct_declarator """ p[0] = self._type_modify_decl(p[2], p[1]) # Since it's impossible for a type to be specified after a pointer, assume # it's intended to be the name for this declaration. _add_identifier will # raise an error if this TYPEID can't be redeclared. # def p_declarator_3(self, p): """ declarator : pointer TYPEID """ decl = c_ast.TypeDecl( declname=p[2], type=None, quals=None, coord=self._coord(p.lineno(2))) p[0] = self._type_modify_decl(decl, p[1]) def p_direct_declarator_1(self, p): """ direct_declarator : ID """ p[0] = c_ast.TypeDecl( declname=p[1], type=None, quals=None, coord=self._coord(p.lineno(1))) def p_direct_declarator_2(self, p): """ direct_declarator : LPAREN declarator RPAREN """ p[0] = p[2] def p_direct_declarator_3(self, p): """ direct_declarator : direct_declarator LBRACKET type_qualifier_list_opt assignment_expression_opt RBRACKET """ quals = (p[3] if len(p) > 5 else []) or [] # Accept dimension qualifiers # Per C99 6.7.5.3 p7 arr = c_ast.ArrayDecl( type=None, dim=p[4] if len(p) > 5 else p[3], dim_quals=quals, coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=arr) def p_direct_declarator_4(self, p): """ direct_declarator : direct_declarator LBRACKET STATIC type_qualifier_list_opt assignment_expression RBRACKET | direct_declarator LBRACKET type_qualifier_list STATIC assignment_expression RBRACKET """ # Using slice notation for PLY objects doesn't work in Python 3 for the # version of PLY embedded with pycparser; see PLY Google Code issue 30. # Work around that here by listing the two elements separately. listed_quals = [item if isinstance(item, list) else [item] for item in [p[3],p[4]]] dim_quals = [qual for sublist in listed_quals for qual in sublist if qual is not None] arr = c_ast.ArrayDecl( type=None, dim=p[5], dim_quals=dim_quals, coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=arr) # Special for VLAs # def p_direct_declarator_5(self, p): """ direct_declarator : direct_declarator LBRACKET type_qualifier_list_opt TIMES RBRACKET """ arr = c_ast.ArrayDecl( type=None, dim=c_ast.ID(p[4], self._coord(p.lineno(4))), dim_quals=p[3] if p[3] != None else [], coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=arr) def p_direct_declarator_6(self, p): """ direct_declarator : direct_declarator LPAREN parameter_type_list RPAREN | direct_declarator LPAREN identifier_list_opt RPAREN """ func = c_ast.FuncDecl( args=p[3], type=None, coord=p[1].coord) # To see why _get_yacc_lookahead_token is needed, consider: # typedef char TT; # void foo(int TT) { TT = 10; } # Outside the function, TT is a typedef, but inside (starting and # ending with the braces) it's a parameter. The trouble begins with # yacc's lookahead token. We don't know if we're declaring or # defining a function until we see LBRACE, but if we wait for yacc to # trigger a rule on that token, then TT will have already been read # and incorrectly interpreted as TYPEID. We need to add the # parameters to the scope the moment the lexer sees LBRACE. # if self._get_yacc_lookahead_token().type == "LBRACE": if func.args is not None: for param in func.args.params: if isinstance(param, c_ast.EllipsisParam): break self._add_identifier(param.name, param.coord) p[0] = self._type_modify_decl(decl=p[1], modifier=func) def p_pointer(self, p): """ pointer : TIMES type_qualifier_list_opt | TIMES type_qualifier_list_opt pointer """ coord = self._coord(p.lineno(1)) # Pointer decls nest from inside out. This is important when different # levels have different qualifiers. For example: # # char * const * p; # # Means "pointer to const pointer to char" # # While: # # char ** const p; # # Means "const pointer to pointer to char" # # So when we construct PtrDecl nestings, the leftmost pointer goes in # as the most nested type. nested_type = c_ast.PtrDecl(quals=p[2] or [], type=None, coord=coord) if len(p) > 3: tail_type = p[3] while tail_type.type is not None: tail_type = tail_type.type tail_type.type = nested_type p[0] = p[3] else: p[0] = nested_type def p_type_qualifier_list(self, p): """ type_qualifier_list : type_qualifier | type_qualifier_list type_qualifier """ p[0] = [p[1]] if len(p) == 2 else p[1] + [p[2]] def p_parameter_type_list(self, p): """ parameter_type_list : parameter_list | parameter_list COMMA ELLIPSIS """ if len(p) > 2: p[1].params.append(c_ast.EllipsisParam(self._coord(p.lineno(3)))) p[0] = p[1] def p_parameter_list(self, p): """ parameter_list : parameter_declaration | parameter_list COMMA parameter_declaration """ if len(p) == 2: # single parameter p[0] = c_ast.ParamList([p[1]], p[1].coord) else: p[1].params.append(p[3]) p[0] = p[1] def p_parameter_declaration_1(self, p): """ parameter_declaration : declaration_specifiers declarator """ spec = p[1] if not spec['type']: spec['type'] = [c_ast.IdentifierType(['int'], coord=self._coord(p.lineno(1)))] p[0] = self._build_declarations( spec=spec, decls=[dict(decl=p[2])])[0] def p_parameter_declaration_2(self, p): """ parameter_declaration : declaration_specifiers abstract_declarator_opt """ spec = p[1] if not spec['type']: spec['type'] = [c_ast.IdentifierType(['int'], coord=self._coord(p.lineno(1)))] # Parameters can have the same names as typedefs. The trouble is that # the parameter's name gets grouped into declaration_specifiers, making # it look like an old-style declaration; compensate. # if len(spec['type']) > 1 and len(spec['type'][-1].names) == 1 and \ self._is_type_in_scope(spec['type'][-1].names[0]): decl = self._build_declarations( spec=spec, decls=[dict(decl=p[2], init=None)])[0] # This truly is an old-style parameter declaration # else: decl = c_ast.Typename( name='', quals=spec['qual'], type=p[2] or c_ast.TypeDecl(None, None, None), coord=self._coord(p.lineno(2))) typename = spec['type'] decl = self._fix_decl_name_type(decl, typename) p[0] = decl def p_identifier_list(self, p): """ identifier_list : identifier | identifier_list COMMA identifier """ if len(p) == 2: # single parameter p[0] = c_ast.ParamList([p[1]], p[1].coord) else: p[1].params.append(p[3]) p[0] = p[1] def p_initializer_1(self, p): """ initializer : assignment_expression """ p[0] = p[1] def p_initializer_2(self, p): """ initializer : brace_open initializer_list_opt brace_close | brace_open initializer_list COMMA brace_close """ if p[2] is None: p[0] = c_ast.InitList([], self._coord(p.lineno(1))) else: p[0] = p[2] def p_initializer_list(self, p): """ initializer_list : designation_opt initializer | initializer_list COMMA designation_opt initializer """ if len(p) == 3: # single initializer init = p[2] if p[1] is None else c_ast.NamedInitializer(p[1], p[2]) p[0] = c_ast.InitList([init], p[2].coord) else: init = p[4] if p[3] is None else c_ast.NamedInitializer(p[3], p[4]) p[1].exprs.append(init) p[0] = p[1] def p_designation(self, p): """ designation : designator_list EQUALS """ p[0] = p[1] # Designators are represented as a list of nodes, in the order in which # they're written in the code. # def p_designator_list(self, p): """ designator_list : designator | designator_list designator """ p[0] = [p[1]] if len(p) == 2 else p[1] + [p[2]] def p_designator(self, p): """ designator : LBRACKET constant_expression RBRACKET | PERIOD identifier """ p[0] = p[2] def p_type_name(self, p): """ type_name : specifier_qualifier_list abstract_declarator_opt """ #~ print '==========' #~ print p[1] #~ print p[2] #~ print p[2].children() #~ print '==========' typename = c_ast.Typename( name='', quals=p[1]['qual'], type=p[2] or c_ast.TypeDecl(None, None, None), coord=self._coord(p.lineno(2))) p[0] = self._fix_decl_name_type(typename, p[1]['type']) def p_abstract_declarator_1(self, p): """ abstract_declarator : pointer """ dummytype = c_ast.TypeDecl(None, None, None) p[0] = self._type_modify_decl( decl=dummytype, modifier=p[1]) def p_abstract_declarator_2(self, p): """ abstract_declarator : pointer direct_abstract_declarator """ p[0] = self._type_modify_decl(p[2], p[1]) def p_abstract_declarator_3(self, p): """ abstract_declarator : direct_abstract_declarator """ p[0] = p[1] # Creating and using direct_abstract_declarator_opt here # instead of listing both direct_abstract_declarator and the # lack of it in the beginning of _1 and _2 caused two # shift/reduce errors. # def p_direct_abstract_declarator_1(self, p): """ direct_abstract_declarator : LPAREN abstract_declarator RPAREN """ p[0] = p[2] def p_direct_abstract_declarator_2(self, p): """ direct_abstract_declarator : direct_abstract_declarator LBRACKET assignment_expression_opt RBRACKET """ arr = c_ast.ArrayDecl( type=None, dim=p[3], dim_quals=[], coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=arr) def p_direct_abstract_declarator_3(self, p): """ direct_abstract_declarator : LBRACKET assignment_expression_opt RBRACKET """ p[0] = c_ast.ArrayDecl( type=c_ast.TypeDecl(None, None, None), dim=p[2], dim_quals=[], coord=self._coord(p.lineno(1))) def p_direct_abstract_declarator_4(self, p): """ direct_abstract_declarator : direct_abstract_declarator LBRACKET TIMES RBRACKET """ arr = c_ast.ArrayDecl( type=None, dim=c_ast.ID(p[3], self._coord(p.lineno(3))), dim_quals=[], coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=arr) def p_direct_abstract_declarator_5(self, p): """ direct_abstract_declarator : LBRACKET TIMES RBRACKET """ p[0] = c_ast.ArrayDecl( type=c_ast.TypeDecl(None, None, None), dim=c_ast.ID(p[3], self._coord(p.lineno(3))), dim_quals=[], coord=self._coord(p.lineno(1))) def p_direct_abstract_declarator_6(self, p): """ direct_abstract_declarator : direct_abstract_declarator LPAREN parameter_type_list_opt RPAREN """ func = c_ast.FuncDecl( args=p[3], type=None, coord=p[1].coord) p[0] = self._type_modify_decl(decl=p[1], modifier=func) def p_direct_abstract_declarator_7(self, p): """ direct_abstract_declarator : LPAREN parameter_type_list_opt RPAREN """ p[0] = c_ast.FuncDecl( args=p[2], type=c_ast.TypeDecl(None, None, None), coord=self._coord(p.lineno(1))) # declaration is a list, statement isn't. To make it consistent, block_item # will always be a list # def p_block_item(self, p): """ block_item : declaration | statement """ p[0] = p[1] if isinstance(p[1], list) else [p[1]] # Since we made block_item a list, this just combines lists # def p_block_item_list(self, p): """ block_item_list : block_item | block_item_list block_item """ # Empty block items (plain ';') produce [None], so ignore them p[0] = p[1] if (len(p) == 2 or p[2] == [None]) else p[1] + p[2] def p_compound_statement_1(self, p): """ compound_statement : brace_open block_item_list_opt brace_close """ p[0] = c_ast.Compound( block_items=p[2], coord=self._coord(p.lineno(1))) def p_labeled_statement_1(self, p): """ labeled_statement : ID COLON statement """ p[0] = c_ast.Label(p[1], p[3], self._coord(p.lineno(1))) def p_labeled_statement_2(self, p): """ labeled_statement : CASE constant_expression COLON statement """ p[0] = c_ast.Case(p[2], [p[4]], self._coord(p.lineno(1))) def p_labeled_statement_3(self, p): """ labeled_statement : DEFAULT COLON statement """ p[0] = c_ast.Default([p[3]], self._coord(p.lineno(1))) def p_selection_statement_1(self, p): """ selection_statement : IF LPAREN expression RPAREN statement """ p[0] = c_ast.If(p[3], p[5], None, self._coord(p.lineno(1))) def p_selection_statement_2(self, p): """ selection_statement : IF LPAREN expression RPAREN statement ELSE statement """ p[0] = c_ast.If(p[3], p[5], p[7], self._coord(p.lineno(1))) def p_selection_statement_3(self, p): """ selection_statement : SWITCH LPAREN expression RPAREN statement """ p[0] = fix_switch_cases( c_ast.Switch(p[3], p[5], self._coord(p.lineno(1)))) def p_iteration_statement_1(self, p): """ iteration_statement : WHILE LPAREN expression RPAREN statement """ p[0] = c_ast.While(p[3], p[5], self._coord(p.lineno(1))) def p_iteration_statement_2(self, p): """ iteration_statement : DO statement WHILE LPAREN expression RPAREN SEMI """ p[0] = c_ast.DoWhile(p[5], p[2], self._coord(p.lineno(1))) def p_iteration_statement_3(self, p): """ iteration_statement : FOR LPAREN expression_opt SEMI expression_opt SEMI expression_opt RPAREN statement """ p[0] = c_ast.For(p[3], p[5], p[7], p[9], self._coord(p.lineno(1))) def p_iteration_statement_4(self, p): """ iteration_statement : FOR LPAREN declaration expression_opt SEMI expression_opt RPAREN statement """ p[0] = c_ast.For(c_ast.DeclList(p[3], self._coord(p.lineno(1))), p[4], p[6], p[8], self._coord(p.lineno(1))) def p_jump_statement_1(self, p): """ jump_statement : GOTO ID SEMI """ p[0] = c_ast.Goto(p[2], self._coord(p.lineno(1))) def p_jump_statement_2(self, p): """ jump_statement : BREAK SEMI """ p[0] = c_ast.Break(self._coord(p.lineno(1))) def p_jump_statement_3(self, p): """ jump_statement : CONTINUE SEMI """ p[0] = c_ast.Continue(self._coord(p.lineno(1))) def p_jump_statement_4(self, p): """ jump_statement : RETURN expression SEMI | RETURN SEMI """ p[0] = c_ast.Return(p[2] if len(p) == 4 else None, self._coord(p.lineno(1))) def p_expression_statement(self, p): """ expression_statement : expression_opt SEMI """ if p[1] is None: p[0] = c_ast.EmptyStatement(self._coord(p.lineno(1))) else: p[0] = p[1] def p_expression(self, p): """ expression : assignment_expression | expression COMMA assignment_expression """ if len(p) == 2: p[0] = p[1] else: if not isinstance(p[1], c_ast.ExprList): p[1] = c_ast.ExprList([p[1]], p[1].coord) p[1].exprs.append(p[3]) p[0] = p[1] def p_typedef_name(self, p): """ typedef_name : TYPEID """ p[0] = c_ast.IdentifierType([p[1]], coord=self._coord(p.lineno(1))) def p_assignment_expression(self, p): """ assignment_expression : conditional_expression | unary_expression assignment_operator assignment_expression """ if len(p) == 2: p[0] = p[1] else: p[0] = c_ast.Assignment(p[2], p[1], p[3], p[1].coord) # K&R2 defines these as many separate rules, to encode # precedence and associativity. Why work hard ? I'll just use # the built in precedence/associativity specification feature # of PLY. (see precedence declaration above) # def p_assignment_operator(self, p): """ assignment_operator : EQUALS | XOREQUAL | TIMESEQUAL | DIVEQUAL | MODEQUAL | PLUSEQUAL | MINUSEQUAL | LSHIFTEQUAL | RSHIFTEQUAL | ANDEQUAL | OREQUAL """ p[0] = p[1] def p_constant_expression(self, p): """ constant_expression : conditional_expression """ p[0] = p[1] def p_conditional_expression(self, p): """ conditional_expression : binary_expression | binary_expression CONDOP expression COLON conditional_expression """ if len(p) == 2: p[0] = p[1] else: p[0] = c_ast.TernaryOp(p[1], p[3], p[5], p[1].coord) def p_binary_expression(self, p): """ binary_expression : cast_expression | binary_expression TIMES binary_expression | binary_expression DIVIDE binary_expression | binary_expression MOD binary_expression | binary_expression PLUS binary_expression | binary_expression MINUS binary_expression | binary_expression RSHIFT binary_expression | binary_expression LSHIFT binary_expression | binary_expression LT binary_expression | binary_expression LE binary_expression | binary_expression GE binary_expression | binary_expression GT binary_expression | binary_expression EQ binary_expression | binary_expression NE binary_expression | binary_expression AND binary_expression | binary_expression OR binary_expression | binary_expression XOR binary_expression | binary_expression LAND binary_expression | binary_expression LOR binary_expression """ if len(p) == 2: p[0] = p[1] else: p[0] = c_ast.BinaryOp(p[2], p[1], p[3], p[1].coord) def p_cast_expression_1(self, p): """ cast_expression : unary_expression """ p[0] = p[1] def p_cast_expression_2(self, p): """ cast_expression : LPAREN type_name RPAREN cast_expression """ p[0] = c_ast.Cast(p[2], p[4], self._coord(p.lineno(1))) def p_unary_expression_1(self, p): """ unary_expression : postfix_expression """ p[0] = p[1] def p_unary_expression_2(self, p): """ unary_expression : PLUSPLUS unary_expression | MINUSMINUS unary_expression | unary_operator cast_expression """ p[0] = c_ast.UnaryOp(p[1], p[2], p[2].coord) def p_unary_expression_3(self, p): """ unary_expression : SIZEOF unary_expression | SIZEOF LPAREN type_name RPAREN """ p[0] = c_ast.UnaryOp( p[1], p[2] if len(p) == 3 else p[3], self._coord(p.lineno(1))) def p_unary_operator(self, p): """ unary_operator : AND | TIMES | PLUS | MINUS | NOT | LNOT """ p[0] = p[1] def p_postfix_expression_1(self, p): """ postfix_expression : primary_expression """ p[0] = p[1] def p_postfix_expression_2(self, p): """ postfix_expression : postfix_expression LBRACKET expression RBRACKET """ p[0] = c_ast.ArrayRef(p[1], p[3], p[1].coord) def p_postfix_expression_3(self, p): """ postfix_expression : postfix_expression LPAREN argument_expression_list RPAREN | postfix_expression LPAREN RPAREN """ p[0] = c_ast.FuncCall(p[1], p[3] if len(p) == 5 else None, p[1].coord) def p_postfix_expression_4(self, p): """ postfix_expression : postfix_expression PERIOD ID | postfix_expression PERIOD TYPEID | postfix_expression ARROW ID | postfix_expression ARROW TYPEID """ field = c_ast.ID(p[3], self._coord(p.lineno(3))) p[0] = c_ast.StructRef(p[1], p[2], field, p[1].coord) def p_postfix_expression_5(self, p): """ postfix_expression : postfix_expression PLUSPLUS | postfix_expression MINUSMINUS """ p[0] = c_ast.UnaryOp('p' + p[2], p[1], p[1].coord) def p_postfix_expression_6(self, p): """ postfix_expression : LPAREN type_name RPAREN brace_open initializer_list brace_close | LPAREN type_name RPAREN brace_open initializer_list COMMA brace_close """ p[0] = c_ast.CompoundLiteral(p[2], p[5]) def p_primary_expression_1(self, p): """ primary_expression : identifier """ p[0] = p[1] def p_primary_expression_2(self, p): """ primary_expression : constant """ p[0] = p[1] def p_primary_expression_3(self, p): """ primary_expression : unified_string_literal | unified_wstring_literal """ p[0] = p[1] def p_primary_expression_4(self, p): """ primary_expression : LPAREN expression RPAREN """ p[0] = p[2] def p_primary_expression_5(self, p): """ primary_expression : OFFSETOF LPAREN type_name COMMA identifier RPAREN """ coord = self._coord(p.lineno(1)) p[0] = c_ast.FuncCall(c_ast.ID(p[1], coord), c_ast.ExprList([p[3], p[5]], coord), coord) def p_argument_expression_list(self, p): """ argument_expression_list : assignment_expression | argument_expression_list COMMA assignment_expression """ if len(p) == 2: # single expr p[0] = c_ast.ExprList([p[1]], p[1].coord) else: p[1].exprs.append(p[3]) p[0] = p[1] def p_identifier(self, p): """ identifier : ID """ p[0] = c_ast.ID(p[1], self._coord(p.lineno(1))) def p_constant_1(self, p): """ constant : INT_CONST_DEC | INT_CONST_OCT | INT_CONST_HEX | INT_CONST_BIN """ p[0] = c_ast.Constant( 'int', p[1], self._coord(p.lineno(1))) def p_constant_2(self, p): """ constant : FLOAT_CONST | HEX_FLOAT_CONST """ p[0] = c_ast.Constant( 'float', p[1], self._coord(p.lineno(1))) def p_constant_3(self, p): """ constant : CHAR_CONST | WCHAR_CONST """ p[0] = c_ast.Constant( 'char', p[1], self._coord(p.lineno(1))) # The "unified" string and wstring literal rules are for supporting # concatenation of adjacent string literals. # I.e. "hello " "world" is seen by the C compiler as a single string literal # with the value "hello world" # def p_unified_string_literal(self, p): """ unified_string_literal : STRING_LITERAL | unified_string_literal STRING_LITERAL """ if len(p) == 2: # single literal p[0] = c_ast.Constant( 'string', p[1], self._coord(p.lineno(1))) else: p[1].value = p[1].value[:-1] + p[2][1:] p[0] = p[1] def p_unified_wstring_literal(self, p): """ unified_wstring_literal : WSTRING_LITERAL | unified_wstring_literal WSTRING_LITERAL """ if len(p) == 2: # single literal p[0] = c_ast.Constant( 'string', p[1], self._coord(p.lineno(1))) else: p[1].value = p[1].value.rstrip()[:-1] + p[2][2:] p[0] = p[1] def p_brace_open(self, p): """ brace_open : LBRACE """ p[0] = p[1] def p_brace_close(self, p): """ brace_close : RBRACE """ p[0] = p[1] def p_empty(self, p): 'empty : ' p[0] = None def p_error(self, p): # If error recovery is added here in the future, make sure # _get_yacc_lookahead_token still works! # if p: self._parse_error( 'before: %s' % p.value, self._coord(lineno=p.lineno, column=self.clex.find_tok_column(p))) else: self._parse_error('At end of input', '') #------------------------------------------------------------------------------ if __name__ == "__main__": import pprint import time, sys #t1 = time.time() #parser = CParser(lex_optimize=True, yacc_debug=True, yacc_optimize=False) #sys.write(time.time() - t1) #buf = ''' #int (*k)(int); #''' ## set debuglevel to 2 for debugging #t = parser.parse(buf, 'x.c', debuglevel=0) #t.show(showcoord=True)