如何忽略ANTLR4中的某些文本？

Question

first of all, thank you in advance for your answer, this problem is killing me

1. My first question is how can ignore certain text? I wanna ignore certain text from my document, I have the next text:

And I wanna ignore the text enclosed by the rectangle...when the lexer find the "demandante" word it will stop to ignore...

I used this grammar

grammar A;

documento:((acciondemandante acciondemandado) | (acciondemandado acciondemandante));
acciondemandante: PALABRASDEMANDA informacionentidad+;
acciondemandado: PALABRASDEMANDADO informacionentidad+;
informacionentidad: nombres distancia? identificacion;
nombres: nombrenormal|nombremayuscula; 
nombrenormal: WORDCAPITALIZE WORDCAPITALIZE+;
nombremayuscula: WORDUPPER WORDUPPER+;
distancia: WORDLOWER;
identificacion: tipo indicador? INT+;
tipo: cedula | NIT;
cedula: CEDULA | LCASE_LETTER LCASE_LETTER | UCASE_LETTER UCASE_LETTER;
indicador: WORDCAPITALIZE | WORDLOWER;

CEDULA: 'cedula' | 'cc' | 'CC';
NIT: 'NIT' | 'nit';
PALABRASDEMANDADO: 'demandados' | 'demandado';
PALABRASDEMANDA: 'demandante' | 'demandantes';
WORDUPPER: UCASE_LETTER UCASE_LETTER+;
WORDLOWER: LCASE_LETTER LCASE_LETTER+;
WORDCAPITALIZE: UCASE_LETTER LCASE_LETTER+;
LCASE_LETTER: 'a'..'z' | 'ñ' | 'á' | 'é' | 'í' | 'ó' | 'ú';
UCASE_LETTER: 'A'..'Z' | 'Ñ' | 'Á' | 'É' | 'Í' | 'Ó' | 'Ú';
INT: DIGIT+;
DIGIT: '0'..'9';  
SPECIAL_CHAR: '.'  -> skip;
WS : [ \t\r\n]+ -> skip;
//ANY: ~[ ]+;

I have tried a trick skipping the whitespaces WS : [ \\t\\r\\n]+ -> skip; and then ignoring what is not whitespaces ANY: ~[ ]+; But it does not work because the lexer never recognize the ANY token...

What I would like my grammar to read

bullshit bullshit demandado Julian Solarte cc 120109321 bullshit bullshit

2. My second problem is that I get the "mismatched input ''" problem, and in order to resolve this problem I add this rule "SKIPEND: EOF ->skip;" but it does not works...

Thank you thank you so much.

Answer 1

My approach to this problem would be 2 steps:

1. Find the keyword in the input stream (here demandado ).
2. Let a parser parse from this position without forcing an EOF for the input in the grammar. It will go as far as possible ignoring everything it doesn't understand after what was understood.

This will make your grammar much simpler and you will get a parse tree only for the relevant input.