Daniel Sun created GROOVY-12322:
-----------------------------------
Summary: 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
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)
