CODEWITHSUNDEEP
antlrantlr4
Hoang
Hoang

Reputation: 29

ANTLR4: How to hide a specific character?

I am new to ANTLR4 and have a trouble.

I want to have the code accept integers with _ between digits, but the output would not include _ characters. For example: it would accept 12_34_5 and the expected token would be 12345.

Is there a way to do that in ANTLR4?

Upvotes: 1

Views: 206

Answers (1)

kaby76
kaby76

Reputation: 1408

I think what you mean by "output would not include _ characters" is to rewrite the text value of the recognized token. The "output" of a parse is a parse tree.

Use a lexer action.

CSharp:

grammar Rewrite;
everything: .* EOF;
Int: [0-9_]+ { Text = Text.Replace("_",""); };
WS: [ \n\r\t]+ -> skip;

Note, the "action code" is target-specific, i.e., in C# for the CSharp target. You will need to change the action code for another target.

Upvotes: 2

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