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Asked: 2026-05-27T15:23:53+00:00

Im trying to write very simple HTML parser with ANTLR and Im facing problem,

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Im trying to write very simple HTML parser with ANTLR and Im facing problem, that ~ rule which should match all until specified character is not working.

My lexer grammar:

lexer grammar HtmlParserLexer;

HTML: OHTML PCDATA CHTML;

PCDATA :(~'<') ; //match all until <

OHTML: '<html>';

CHTML: '</html>';

Im trying to match:

<html>foo bar</html>

Error from Eclipse ANTLR plugin Interpreter:

MismatchedTokenException: line 1:7 mismatched input UNKNOW expecting '<'

Which means, that my grammar ignore PCDATA rule and I dont know why.
Thanks in advance for your help.

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1 Answer

  1. Editorial Team

    The rule PCDATA :(~'<') ; matches a single character other than '<'. You’ll need to repeat it once or more: PCDATA :(~'<')+ ; (notice the +).

    You may also want to allow <html></html> (nothing in between<html> and </html>). In that case, you shouldn’t change PCDATA :(~'<')+ ; into PCDATA :(~'<')* ;, but do this instead:

    HTML: OHTML PCDATA? CHTML;

PCDATA : (~'<')+ ;

    because you shouldn’t create lexer rules that could potentially match an empty string.

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