Question

PetitParser中的规则是否分配？

接下来有规则：

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

如果我将它们改为：

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

然后0777L不再被解析了。它应与octalNumeral , (integerTypeSuffix optional)或新版本octalIntegerLiteral , (integerTypeSuffix optional)匹配，但这不会发生。

Answer 1

是的，PetitParser中的有序选择是分配式的。在你的例子中有一些上下文缺失，所以我不知道它为什么不适合你。

PetitParser优化器会自动执行您建议的更改。重写规则（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

PetitParser不分配？

1 个答案: