[
https://issues.apache.org/jira/browse/GROOVY-12322?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18109678#comment-18109678
]
ASF GitHub Bot commented on GROOVY-12322:
-----------------------------------------
daniellansun opened a new pull request, #2848:
URL: https://github.com/apache/groovy/pull/2848
https://issues.apache.org/jira/browse/GROOVY-12322
> Inline the nls parser rule
> --------------------------
>
> Key: GROOVY-12322
> URL: https://issues.apache.org/jira/browse/GROOVY-12322
> Project: Groovy
> Issue Type: Improvement
> Reporter: Daniel Sun
> Priority: Major
>
> h3. Motivation
> {{GroovyParser.g4}} used a shared helper for optional newlines:
> {noformat}
> nls : NL* ;
> sep : (NL | SEMI)+ ;
> {noformat}
> Because {{sep}} can start with {{NL}}, {{FOLLOW(nls)}} contains {{NL}}. The
> star inside {{nls}} is therefore not LL(1) at the rule level: generated
> {{nls()}} always uses adaptivePredict, even at call sites where a simple
> {{while (LA(1)==NL)}} would be correct. The rule also allocates a
> {{NlsContext}} for every invocation, including the empty match.
> {{classOrInterfaceModifiersOpt}} already inlined {{NL*}} for this reason,
> with a comment not to put {{nls}} back.
> Same class of prediction-cost reduction as GROOVY-12173, applied to newline
> handling.
> h3. Changes
> * Delete the {{nls}} rule and write {{NL*}} at every former call site, so
> each site has its own star decision.
> * Teach {{GroovydocManager}} to read {{NL}} terminals as direct children
> (comments are lexed as {{NL}}). {{sep}} still wraps mixed {{NL}} / {{SEMI}}
> sequences.
> h3. Compatibility
> * Language and AST for correct programs are unchanged.
> * Parse-tree shape changes: no {{NlsContext}}; empty matches produce no
> child. {{NlsContext}} is generated parser API, not a stability covenant.
> * No public API additions.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
