How to return a parsing rule context in ANTLR 4?
Returns a range indicating the index in the TokenStream of the first and last token associated with this subtree. Get the initial token in this context. Get the final token in this context. Used by enterOuterAlt to discard a previously added RuleContext when we enter a rule. Methods inherited from the org.antlr.v4.runtime class. RuleContext
Table of Contents
How do you return text from a parserrulecontext?
Subclasses created for each rule and grammar track the parameters, return values, locales, and labels specific to that rule. These are the objects that are returned from the rules. The note text is not an actual field of a rule’s return value; is calculated from the start and to the end using the toString() method of the input stream.
How is the current rule stored in the parse tree?
Contains all information about the current rule that is not stored in the RuleContext. It handles the list of parse tree children, the tracking of any ATN state, and the default values available for rule invocations: start, stop, rule index, current alt number.
How to create a parse tree child in ANTLR 4?
Add a parse tree node to this as a child. Add a token leaf child node and force its parent to be this node. Outdated. Add a child error node and force its parent to be this node. Outdated. COPY to ctx (I am deliberately not using the copy constructor) to avoid confusion with creating a node with parent.
How is an ANTLR4 lexer different from a parser?
Antlr4 also enables implicit literal token values sprinkled into grammar rules. For example, our demo lexer includes implicit tokens ‘+’, ‘*’, “%’, and ‘-‘, which appear in the parser grammar. A lexer, unlike a parser, does not care about the order of the tokens. There is no context between tokens.
What do you need to know about using ANTLR?
When you use ANTLR you start by writing a grammar, a file with a .g4 extension that contains the rules of the language you are parsing. It then uses the antlr4 program to generate the files that your program will actually use, such as the lexer and parser. There are a couple of important options that you can specify when running antlr4.
How do you write a grammar file in ANTLR?
When you use ANTLR you start by writing a grammar, a file with a .g4 extension that contains the rules of the language you are parsing. It then uses the antlr4 program to generate the files that your program will actually use, such as the lexer and parser.