Antlr - Lexer Grammar

Card Puncher Data Processing

About

The grammar file of the lexer is composed of lexer rule, optionally broken into multiple lexical modes

The most common approach is to combine combined in in one grammar file, the lexer and parser grammar.

Characteristics

Only lexer grammars can contain:

  • mode specifications.
  • custom channels specifications

Syntax

lexer grammar Name;
...

In the parser grammar, you define the lexer with the tokenVocab option.

parser grammar MarkupParser;

options { tokenVocab=MarkupLexer; }





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Card Puncher Data Processing
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When you don't want to check for non-semantic rule such as comments / whitespace, you can throw them away with -> skip but if you want to preserve them, you use channels. Only lexer grammars can...
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in Antlr. They are rules that defines tokens. They are written generally in the grammar but may be written in a lexer grammar file Each lexer rule is either matched or not so every lexer rule expression...
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Antlr - Lexical mode

Lexical mode in Antlr Lexical modes allow to split a single lexer grammar file into multiple sublexers. The lexer can then only return tokens matched by rules from the current mode. Lexers start out...
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Antlr - Parser Grammar

The grammar file of the parser contains the parser rule. grammar file If you have two differents file and your lexer grammar is defined in another file, you need to define it with the tokenVocab...



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