Not skip whitespace

[Mohan Radhakrishnan]

Hi,

          The Java grammar skips whitespaces ? I am losing comments and code formatting. How can I keep them and use them ?

So, for example, I want to keep the empty lines in this code.

package com.nationwide.pc.is.tpi.web.action;

import java.util.Enumeration;

Java.g4 has this.

WS  :  [ \t\r\n\u000C]+ -> skip
    ;

COMMENT
    :   '/*' .*? '*/' -> skip
    ;

LINE_COMMENT
    :   '//' ~[\r\n]* -> skip
    ;

Thanks,

Mohan

[Jim Idle]

Look in to lexer channels. You can send the whitespace et al to a different channel that the Parser will ignore but are available to you to render. 

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[Mohan Radhakrishnan]

WS  :  [ \t\r\n\u000C]+ -> channel(HIDDEN)
    ;

I tried this.

The standard code I find by searching is this. Whether I use DEFAULT_CHANNEL or HIDDEN_CHANNEL I still see the code. I thought DEFAULT_CHANNEL 

should have only code without whitespaces and HIDDEN_CHANNEL should have only spaces.

public void enterMethodDeclaration( JavaParser.MethodDeclarationContext ctx){

        ParserRuleContext parent = ctx.getParent();

        while (parent!=null && !(parent instanceof JavaParser.ClassBodyDeclarationContext)) {
            parent = parent.getParent();
        }
        if (parent == null) {
            parent = ctx;
        }
        Token start = parent.start;
        // work backwards in token stream to include all preceding whitespace and comments
        int tokenIndex = start.getTokenIndex();
        while ( tokenIndex > 0 && tokens.get(tokenIndex-1).getChannel() != Token.DEFAULT_CHANNEL ) {
            tokenIndex--;
        }
        int startIndex = start.getStartIndex();
        int endIndex = ctx.stop.getStopIndex();
        Interval interval = new Interval(startIndex,endIndex);
}

Mohan

[Mohan Radhakrishnan]

Hi,

      Is my approach right ? Can anyone nudge in the right direction ?

Update : This works.

((CommonTokenStream) tokens).getHiddenTokensToLeft( classOrInterfaceModifierContext.getStart().getTokenIndex(),
                                                    Token.HIDDEN_CHANNEL);

I get the comments and whitespaces before each method.

Thanks,

Mohan

[Niels Basjes]

Have a look at what I did https://github.com/nielsbasjes/yauaa/blob/SPACE_Skip/src/main/java/nl/basjes/parse/useragent/utils/AntlrUtils.java#L32

Perhaps this helps ?

Niels

Op vrijdag 8 juli 2016 08:24:29 UTC+2 schreef Mohan Radhakrishnan:

[miwor...@gmail.com]

Page not found,can you fix the address,thanks.

在 2016年7月9日星期六 UTC+8下午9:09:10，Niels Basjes写道：

[Niels Basjes]

Updated link

https://github.com/nielsbasjes/yauaa/blob/master/analyzer/src/main/java/nl/basjes/parse/useragent/utils/AntlrUtils.java#L32

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Best regards / Met vriendelijke groeten,

Niels Basjes