Block style conditional statements in actions

[ixti]

Right now one need to write cond. stmts like this:

if (yytext.slice(-1) === '\\')
  yytext = yytext.substr(0, yyleng-1),
  do_more
else
  do_other;

it would be great to be able to use braces :))

[jasonwyatt]

You can use braces if you also use double-braces to wrap your action:

{{
    if (ytext.slice(-1) === '\\') {
        yytext = yytext.substr(0, yyleng-1),
        // do more
    } else {
        // do other
    }
}}

Hope this helps!

[ixti]

@jasonwyatt Thanks. That works for parser. But not for lexer...

To be more visual, here's what I mean. Following works perfectly:

%lex

%%

.* {
     return "FOOBAR";
   }

/lex

%start test

%%

test
  : FOOBAR EOF {{
    if (true) {
      console.log('test');
    }

    return $$;
  }}
  ;

But this one fails:

%lex

%%

.* {{
     if (true) {
      console.log('test');
     }
     return "FOOBAR";
   }}

/lex

%start test

%%

test
  : FOOBAR EOF {{
    if (true) {
      console.log('test');
    }

    return $$;
  }}
  ;

The last one gives me following on attempt to compile:

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
SyntaxError: Unexpected token case
    at Function (unknown source)
    at Object.buildActions (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/lexer.js:111:12)
    at Object.RegExpLexer (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/lexer.js:122:39)
    at [object Object].Jison_Generator (/home/ixti/projects/ndoc/node_modules/jison/lib/jison.js:102:22)
    at [object Object].<anonymous> (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/util/typal.js:23:28)
    at new <anonymous> (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/util/typal.js:77:70)
    at new Jison_Generator (/home/ixti/projects/ndoc/node_modules/jison/lib/jison.js:1527:20)
    at processGrammar (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/cli-wrapper.js:76:21)
    at Object.main (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/cli-wrapper.js:48:46)
    at Object.<anonymous> (/home/ixti/projects/ndoc/node_modules/jison/lib/jison/cli-wrapper.js:81:13)

[jasonwyatt]

@ixti Ah, after looking through the source a bit, I think this is how you can do multi-line actions with braces in the lexer config:

.* %{
        if (true) {
            console.log('test');
        }
        return "FOOBAR";
    %}

[ixti]

Oops. You're right! I was trying it before but it as not working - seems I was missing something (probably I was misspelling closing brace)

[ixti]

@jasonwyatt thanks!

[zaach]

I'll reopen this as a reminder that I still need to implement block style with single braces.