Use less stack space while parsing if-statements #41657
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Tagging @RikkiGibson @jcouv @cston |
CyrusNajmabadi
commented
Feb 13, 2020
| this.EatToken(SyntaxKind.CloseParenToken), | ||
| this.ParseEmbeddedStatement(), | ||
| this.ParseElseClauseOpt()); | ||
| } |
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optimie the fast path of a normal if-statement, with no need for flow control or storage for flow control temps.
CyrusNajmabadi
commented
Feb 13, 2020
| this.ParseElseClauseOpt()); | ||
| } | ||
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| private IfStatementSyntax ParseMisplacedElse() |
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MisplacedElse is a very rare case (usually just in the IDE as people are typing). it's fine for it to have it's own dedicated parsing method.
RikkiGibson
reviewed
Feb 13, 2020
| return this.ParseIfStatement(); | ||
| case SyntaxKind.ElseKeyword: | ||
| // Including 'else' keyword to handle 'else without if' error cases | ||
| return this.ParseMisplacedElse(); |
RikkiGibson
reviewed
Feb 13, 2020
| return _syntaxFactory.IfStatement(@if, openParen, condition, closeParen, statement, elseClause); | ||
| return _syntaxFactory.IfStatement( | ||
| this.EatToken(SyntaxKind.IfKeyword, ErrorCode.ERR_ElseCannotStartStatement), | ||
| this.EatToken(SyntaxKind.OpenParenToken), |
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Should we call EatToken, ParseExpressionCore, etc in this way even though we know they will always fail? Basically everything before 'ParseElseClauseOpt'?
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Yes. That's the idea (and what the code did before). It effectively synthesizes the missing nodes/tokens we want here
RikkiGibson
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Feb 13, 2020
RikkiGibson
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cston
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Feb 13, 2020
ghost
merged commit
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Thanks! |
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This gives us the ability to parse about 30 more frames during heavily recursive scenarios.