Python parser generation: rule can't have same name as python identifier

[BenBanerjeeRichards]

If a grammar contains a rule with the same name as a python keyword, then the generated parser will contain a function with the name of a python keyword - this creates a python syntax error.

For example, if the grammar Test has the rule if: IDENTIFIER; then in TestLangParser.py the following code is generated

   class IfContext(ParserRuleContext):
            #...
            def if(self): # Syntax error: identifier expected
                    localctx = TestLangParser.IfContext(self, self._ctx, self.state)
                   #...

Stack trace when running antlr4-python3-runtime:

Traceback (most recent call last):
  File "C:/Users/Ben/Desktop/benlang/grammar/parser.py", line 3, in <module>
    from BenLangVisitor import BenLangVisitor
  File "C:\Users\Ben\Desktop\benlang\grammar\BenLangVisitor.py", line 6, in <module>
    from BenLangParser import BenLangParser
  File "C:\Users\Ben\Desktop\benlang\grammar\BenLangParser.py", line 338
    def if(self):
         ^
SyntaxError: invalid syntax

Exact grammar extract:

grammar BenLang;		
prog:		statement progRest;
progRest:	SEMICOLON statement progRest | ;
statement: 	expr | bool_expr;

if:		IF LBRACKET bool_expr RBRACKET;

Python version: 3.6
Antlr version: 4.7.1

[ericvergnaud]

H, thanks for this. Indeed the core keywords were missing in the list of bad words, only the reserved identifiers were there. Weird… Eric

…

Le 31 déc. 2017 à 22:24, Ben Banerjee-Richards ***@***.***> a écrit : If a grammar contains a rule with the same name as a python keyword, then the generated parser will contain a function with the name of a python keyword - this creates a python syntax error. For example, if the grammar Test has the rule if: IDENTIFIER; then in TestLangParser.py the following code is generated class IfContext(ParserRuleContext): #... def if(self): # Syntax error: identifier expected localctx = TestLangParser.IfContext(self, self._ctx, self.state) #... Stack trace when running antlr4-python3-runtime: Traceback (most recent call last): File "C:/Users/Ben/Desktop/benlang/grammar/parser.py", line 3, in <module> from BenLangVisitor import BenLangVisitor File "C:\Users\Ben\Desktop\benlang\grammar\BenLangVisitor.py", line 6, in <module> from BenLangParser import BenLangParser File "C:\Users\Ben\Desktop\benlang\grammar\BenLangParser.py", line 338 def if(self): ^ SyntaxError: invalid syntax Exact grammar extract: grammar BenLang; prog: statement progRest; progRest: SEMICOLON statement progRest | ; statement: expr | bool_expr; if: IF LBRACKET bool_expr RBRACKET; Python version: 3.6 Antlr version: 4.7.1 — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2188>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ADLYJPXwvSwDKaUyfTDQp_-f5Wi8-fudks5tF5kCgaJpZM4RP3Dd>.