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Subject: Re: More Antlr4-based Groovy parser status update
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From: Pascal Schumacher <pascalschumacher@gmx.net>
Message-ID: <56D32D1D.6070303@gmx.net>
Date: Sun, 28 Feb 2016 18:23:41 +0100
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Hi Jesper,

thanks for the update. :) Nice to hear you are progressing.

Concerning the ASTBuilder to Java conversion, there is a pull request 
with this at the old repo https://github.com/groovy/groovy-core/pull/513

Cheers,
Pascal

Am 28.02.2016 um 12:55 schrieb Jesper Steen Møller:
> Hi Groovy-Dev
>
> Here’s another update on the progress on the Antlr4 parser, as 
> maintained on *https://github.com/jespersm/groovy.git* (in the 
> *antlr4* branch).
> To play with it, try:
>
>     $ git clone -b antlr4 https://jespersm@github.com/jespersm/groovy.git
>     $ cd groovy
>     $ gradle -PuseAntlr4=true console
>
>
> I’ve fixed a number of issues:
>
>   * Support method pointer operator
>   * Attributes/method/property names as strings/gstrings
>   * Real support for unary plus and minus (mimics old parser’s behaviour)
>   * Compilation units not ending with semicolon or newline
>   * Slashy strings could span lines, confusing division statements and
>     comments
>
> I can now explore the new grammar and AST building using the Console, 
> which is fun, but it’s very easy to find unsupported constructs. 
> Mapping out the full Groovy grammar from the documentation alone is 
> quite a task. Just today, I discovered lacking support for ‘assert’ 
> and for ’super’-calls. The smaller issues currently are:
>
>   * assert
>   * super()
>   * Full Unicode letter support  for identifiers
>   * Support identifiers as property names and map literal entry names
>
>
> The bigger issue is with converting the ASTBuilder to pure Java, a 
> task I havn’t started yet. Actually, this poses a different question 
> for AST generation: Whether to switch from tree-walking the parse tree 
> (so whole tree must be kept in memory), to the listener-based 
> approach, where the AST is built mostly bottom-up, ensuring smaller 
> memory footprint.
>
> So you can help me with a couple of answers:
>
>   * Memory: Is this an issue I should be focusing on — and is there a
>     test to baseline against?
>   * I’ve discovered a small issue with unary syntax. Currently, nested
>     unary expressions are not supported without parenthesis: Try e.g.
>     - -1 or + -1. Is this intentional, or just an artifact of the
>     precedence-refactored Java grammar?
>
>
> -Jesper
>


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    <div class="moz-cite-prefix">Hi Jesper,<br>
      <br>
      thanks for the update. :) Nice to hear you are progressing.<br>
      <br>
      Concerning the ASTBuilder to Java conversion, there is a pull
      request with this at the old repo
      <a class="moz-txt-link-freetext" href="https://github.com/groovy/groovy-core/pull/513">https://github.com/groovy/groovy-core/pull/513</a><br>
      <br>
      Cheers,<br>
      Pascal<br>
      <br>
      Am 28.02.2016 um 12:55 schrieb Jesper Steen Møller:<br>
    </div>
    <blockquote
      cite="mid:D2FC84CD-DD73-4A31-86E9-813643D9F0B0@selskabet.org"
      type="cite">
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
      Hi Groovy-Dev
      <div class=""><br class="">
      </div>
      <div class="">Here’s another update on the progress on the Antlr4
        parser, as maintained on <b class=""><a moz-do-not-send="true"
            href="https://github.com/jespersm/groovy.git" class="">https://github.com/jespersm/groovy.git</a></b>
        (in the <b class="">antlr4</b> branch).</div>
      <div class="">To play with it, try:</div>
      <div class=""><br class="">
      </div>
      <blockquote style="margin: 0 0 0 40px; border: none; padding:
        0px;" class="">
        <div class="">$ git clone -b antlr4 <a moz-do-not-send="true"
            href="https://jespersm@github.com/jespersm/groovy.git"
            class="">https://jespersm@github.com/jespersm/groovy.git</a></div>
        <div class="">$ cd groovy</div>
        <div class="">$ gradle -PuseAntlr4=true console</div>
      </blockquote>
      <div class=""><br class="">
      </div>
      <div class="">I’ve fixed a number of issues:</div>
      <div class="">
        <ul class="">
          <li class="">Support method pointer operator</li>
          <li class="">Attributes/method/property names as
            strings/gstrings</li>
          <li class="">Real support for unary plus and minus (mimics old
            parser’s behaviour)</li>
          <li class="">Compilation units not ending with semicolon or
            newline</li>
          <li class="">Slashy strings could span lines, confusing
            division statements and comments</li>
        </ul>
      </div>
      <div class="">I can now explore the new grammar and AST building
        using the Console, which is fun, but it’s very easy to find
        unsupported constructs. Mapping out the full Groovy grammar from
        the documentation alone is quite a task. Just today, I
        discovered lacking support for ‘assert’ and for ’super’-calls.
        The smaller issues currently are:</div>
      <div class="">
        <ul class="MailOutline">
          <li class="">assert</li>
          <li class="">super()</li>
          <li class="">Full Unicode letter support  for identifiers</li>
          <li class="">Support identifiers as property names and map
            literal entry names</li>
        </ul>
      </div>
      <div class=""><br class="">
      </div>
      <div class="">The bigger issue is with converting the ASTBuilder
        to pure Java, a task I havn’t started yet. Actually, this poses
        a different question for AST generation: Whether to switch from
        tree-walking the parse tree (so whole tree must be kept in
        memory), to the listener-based approach, where the AST is built
        mostly bottom-up, ensuring smaller memory footprint.</div>
      <div class=""><br class="">
      </div>
      <div class="">So you can help me with a couple of answers:</div>
      <div class="">
        <ul class="MailOutline">
          <li class="">Memory: Is this an issue I should be focusing on
            — and is there a test to baseline against?</li>
          <li class="">I’ve discovered a small issue with unary syntax.
            Currently, nested unary expressions are not supported
            without parenthesis: Try e.g. - -1 or + -1. Is this
            intentional, or just an artifact of the
            precedence-refactored Java grammar?</li>
        </ul>
      </div>
      <div class=""><br class="">
      </div>
      <div class="">-Jesper</div>
      <div class=""><br class="">
      </div>
    </blockquote>
    <br>
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