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
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
I managed to get this to work with some help from the Webpack team. Using the following webpack configuration as recommended by the antlr4 documentation is no longer supported. Does not work { node: { fs: ’empty’, module: ’empty’, net: ’empty’ } } Working configuration { resolve: { fallback: { fs: false } } } … Read more
Here is quote from the book that I think is relevant: The biggest difference between the listener and visitor mechanisms is that listener methods are called by the ANTLR-provided walker object, whereas visitor methods must walk their children with explicit visit calls. Forgetting to invoke visit() on a node’s children means those subtrees don’t get … Read more
You generated Java source files by running ANTLR on the grammar, but TestRig is looking for compiled .class files. You need to run the Java compiler on the source files before using TestRig.
By default, ANTLR 4 generates listeners. But if you give org.antlr.v4.Tool the command line parameter -visitor, ANTLR generates visitor classes for you. These work much like listeners, but give you more control over which (sub) trees are walked/visited. This is particularly useful if you want to exclude certain (sub) trees (like else/if blocks, as in … Read more