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PetitParser 中的规则是可分配的吗？

有以下规则：

integerLiteral --> hexIntegerLiteral / octalIntegerLiteral / decimalIntegerLiteral
  hexIntegerLiteral     --> hexNumeral , (integerTypeSuffix optional)
  octalIntegerLiteral   --> octalNumeral , (integerTypeSuffix optional)
  decimalIntegerLiteral --> decimalNumeral , (integerTypeSuffix optional)

如果我将它们更改为：

integerLiteral --> (hexIntegerLiteral / octalIntegerLiteral / decimalIntegerLiteral) , (integerTypeSuffix optional)
  hexIntegerLiteral     --> hexNumeral
  octalIntegerLiteral   --> octalNumeral
  decimalIntegerLiteral --> decimalNumeral

then0777L不再被解析。它应该匹配octalNumeral , (integerTypeSuffix optional)或在新版本octalIntegerLiteral , (integerTypeSuffix optional)中，但没有发生。

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1 回答 1

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是的，PetitParser 中的有序选择是分布式的。在您的示例中，缺少一些上下文，所以我不知道为什么它对您不起作用。

PetitParser 优化器会自动执行您建议的更改。重写规则（以稍微更一般的形式）定义为：

PPOptimizer>>#postfixChoice
    <optimize>

    | before prefix body1 body2 postfix after |
    before := PPListPattern any.
    prefix := PPPattern any.
    body1 := PPListPattern any.
    body2 := PPListPattern any.
    postfix := PPPattern any.
    after := PPListPattern any.
    rewriter
        replace: before / (prefix , body1) / (prefix , body2) / after
        with: before / (prefix , (body1 / body2)) / after.
    rewriter
        replace: before / (body1 , postfix) / (body2 , postfix) / after
        with: before / ((body1 / body2) , postfix) / after
于 2013-03-20T15:21:28.643 回答