… what are the practical differences between these two statements in ANTLR … MY_RULE will be used to tokenize your input source. It represents a fundamental building block of your language. my_rule is called from the parser, it consists of zero or more other parser rules or tokens produced by the lexer. That’s the difference. … Read more
The Antlr package is used by the WebGrease package. The WebGrease package is used by the ASP.NET Web Optimization package. If you want to remove Antlr, remove the ASP.NET Web Optimization package. It will in turn remove the other 2 packages. It does not affect performance much, provided that you designed your application properly.
Raphael wrote: Does antlr build the AST for us automatically by option{output=AST;}? Or do I have to make the tree myself? If it does, then how to spit out the nodes on that AST? No, the parser does not know what you want as root and as leaves for each parser rule, so you’ll have … Read more
The v4 equivalent would look like: COMMENT : ( ‘//’ ~[\r\n]* ‘\r’? ‘\n’ | ‘/*’ .*? ‘*/’ ) -> channel(HIDDEN) ; which will put all single- and multi line comment on the HIDDEN channel. However, if you’re not doing anything with these HIDDEN-tokens, you could also skip these tokens, which would look like this: COMMENT … Read more
I highly recommend correcting all instances of this warning in code of any importance. This warning was created (by me actually) to alert you to situations like the following: shiftExpr : ID ((‘<<‘ | ‘>>’) ID)?; Since ANTLR 4 encourages action code be written in separate files in the target language instead of embedding them … Read more
I wouldn’t walk this manually if I were you. After generating a lexer and parser, ANTLR would also have generated a file called CfscriptBaseListener that has empty methods for all of your parser rules. You can let ANTLR walk your tree and attach a custom tree-listener in which you override only those methods/rules you’re interested … Read more
This seems to be a common misunderstanding of ANTLR: Language Processing in ANTLR: The Language Processing is done in two strictly separated phases: Lexing, i.e. partitioning the text into tokens Parsing, i.e. building a parse tree from the tokens Since lexing must preceed parsing there is a consequence: The lexer is independent of the parser, … Read more
It is a transitive dependency declared in the WebGrease package, where it is used for a CSS lexer and parser.
So I haven’t found a way to mark permanently one rule as a start rule, however in the right-click context menu for the grammar, there are two options that relate to ANTLR, one of them is ‘test rule xyz’, that did the job:
ANTLR’s CharStream class has a method getText(Interval interval) which will return the original source in the give range. The Context object has methods to get the beginning and end. Assuming you have a field in your listener called input which has the CharStream being parsed, you can do this: int a = ctx.start.getStartIndex(); int b … Read more