CODEWITHSUNDEEP
antlrdsllexer
user15307601
user15307601

Reputation:

How do I combine ANTLR lexer rules from different lexer grammars?

I am playing around with ANTLR and building a DSL like jsx.

But in jsx you have javasciprt expressions inside {}, how can I define those ECMAScript rules in my lexer grammar? Should I rewrite the whole ECMAScript lexer from scratch or there are some ways to import those rules in my lexer grammar?

<div class={javasciprt expression in here}></div>

Upvotes: 0

Views: 257

Answers (1)

Bart Kiers
Bart Kiers

Reputation: 170308

You can use lexical modes for that:

lexer grammar YourCurrentLexer;

EXISTING_TOKEN
 : '...' 
 ;

// other tokens

ECMA_START
 : '{' -> pushMode(ECMA_MODE)
 ;

mode ECMA_MODE;

 ECMA_TOKEN
  : '...'
  ;

 // other ECMA tokens
 
 // Support nested { ... }
 OPEN_BRACE
  : '{' -> pushMode(ECMA_MODE)
  ;

 CLOSE_BRACE
  : '}' -> popMode
  ;

Should I rewrite the whole ECMAScript lexer from scratch or there are some ways to import those rules in my lexer grammar?

You cannot just import an existing grammar inside a lexical mode. Just copy-paste the rules you want: https://github.com/antlr/grammars-v4/blob/master/javascript/ecmascript/JavaScript/ECMAScript.g4

Upvotes: 1

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