java - Traversal of tokens using ParserRuleContext in listener - ANTLR4 -


while iterating on tokens using listener, know how use parserrulecontext peek @ next token or next few tokens in token stream?

in code below trying peek @ tokens after current token till eof:

@override  public void entersemicolon(javaparser.semicoloncontext ctx) {      token tok, semicolon = ctx.getstart();       int currentindex = semicolon.getstartindex();     int reqind = currentindex+1;     tokensource toksrc= semicolon.gettokensource();     charstream srcstream = semicolon.getinputstream();     srcstream.seek(currentindex);      while(true){          tok = toksrc.nexttoken() ;         system.out.println(tok);         if(tok.gettext()=="<eof>"){break;}         srcstream.seek(reqind++);     } }

but output is:

            .             .             .             .             . [@-1,131:130='',<-1>,13:0] [@-1,132:131='',<-1>,13:0] [@-1,133:132='',<-1>,13:0] [@-1,134:133='',<-1>,13:0] [@-1,135:134='',<-1>,13:0] [@-1,136:135='',<-1>,13:0] [@-1,137:136='',<-1>,13:0] [@-1,138:137='',<-1>,13:0] [@-1,139:138='',<-1>,13:0] [@-1,140:139='',<-1>,13:0] [@-1,141:140='',<-1>,13:0] [@-1,142:141='',<-1>,13:0] [@-1,143:142='',<-1>,13:0] [@-1,144:143='',<-1>,13:0] [@-1,145:144='',<-1>,13:0] [@-1,146:145='',<-1>,13:0] [@-1,147:146='',<-1>,13:0] [@-1,148:147='',<-1>,13:0] [@-1,149:148='',<-1>,13:0] [@-1,150:149='',<-1>,13:0] [@-1,151:150='',<-1>,13:0] [@-1,152:151='',<-1>,13:0] [@-1,153:152='',<-1>,13:0] [@-1,154:153='',<-1>,13:0] [@-1,155:154='',<-1>,13:0] [@-1,156:155='',<-1>,13:0] [@-1,157:156='',<-1>,13:0] [@-1,158:157='',<-1>,13:0] [@-1,159:158='',<-1>,13:0] [@-1,160:159='',<-1>,13:0] [@-1,161:160='<eof>',<-1>,13:0] [@-1,137:136='',<-1>,13:0] [@-1,138:137='',<-1>,13:0] [@-1,139:138='',<-1>,13:0] [@-1,140:139='',<-1>,13:0] [@-1,141:140='',<-1>,13:0] [@-1,142:141='',<-1>,13:0] [@-1,143:142='',<-1>,13:0] [@-1,144:143='',<-1>,13:0] [@-1,145:144='',<-1>,13:0] [@-1,146:145='',<-1>,13:0] [@-1,147:146='',<-1>,13:0] [@-1,148:147='',<-1>,13:0] [@-1,149:148='',<-1>,13:0] [@-1,150:149='',<-1>,13:0] [@-1,151:150='',<-1>,13:0] [@-1,152:151='',<-1>,13:0] [@-1,153:152='',<-1>,13:0] [@-1,154:153='',<-1>,13:0] [@-1,155:154='',<-1>,13:0] [@-1,156:155='',<-1>,13:0] [@-1,157:156='',<-1>,13:0] [@-1,158:157='',<-1>,13:0] [@-1,159:158='',<-1>,13:0] [@-1,160:159='',<-1>,13:0] [@-1,161:160='<eof>',<-1>,13:0]             .             .             .             .

we see although able traverse through tokens till eof, unable actual content or type of tokens. know if there neat way of doing using listener traversing.

hard certain, 

tok = toksrc.nexttoken() ;

appears rerunning lexer, starting @ presumed proper token boundary, without having reset lexer. lexer throwing errors might explain observed behavior.

still, better approach recover existing token stream:

public class walker implements yourjavalistener {      commontokenstream tokens;      public walker(javaparser parser) {         tokens = (commontokenstream) parser.gettokenstream()     }

then access stream desired tokens:

@override  public void entersemicolon(javaparser.semicoloncontext ctx) {     terminalnode semi = ctx.semicolon(); // adjust needed impl.     token tok = semi.getsymbol();     int idx = tok.gettokenindex();      while(tok.gettype() != intstream.eof) {         system.out.println(tok);         tok = tokens.get(idx++);     } }

an entirely different approach might serve ultimate purpose limited set of tokens directly parent context:

parserrulecontext pctx = ctx.getparent(); list<terminalnode> nodes = pctx.gettokens(pctx.getstart(), pctx.getstop());

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