什么是嵌套名称说明符？ [英] What is a nested name specifier?

问题描述

与此相关

我想知道什么是嵌套的名称说明符？我在草稿中查找，但我可以理解语法，因为我还没有采取任何编译器设计类。

  void S （）{} 
 
 struct S {
 S（）{cout< 1;} 
 void f（）{} 
 static const int x = 0; 
}; 
 
 int main（）{
 struct S * p = new struct :: S; 
 p-> :: S :: f（）; 
 
 S :: x; 
 
 :: S（）; // Is :: S是一个嵌套的名称说明符吗？ 
 delete p; 
} 
  

解决方案

:: S 是一个 qualified-id 。

在 qualified-id :: S :: f ， S :: 是一个嵌套名称说明符。

中， id 的一部分

• 在 qualified-id 开头或在初始范围解析运算符（ :: ）之后开始 id 和


• 的最开始处以 qualified-id 中的最后一个范围解析运算符结束。 b $ b

非常正式 ¹ ， id 是 qualified-id 或 unqualified-id 。如果 id 是 qualified-id ，它实际上由两部分组成：嵌套名称说明符后面跟一个 unsqualified-id 。

给定：

  struct A {
 struct B {
 void F（）; 
}; 
}; 
  

• A em>，但没有 nested-name-specifier 。


• A :: B > qualified-id 和 A :: 是一个嵌套名称说明符。


• :: A :: B 是 qualified-id 和 A :: a qualified-id ，并且 B :: 和 A :: B :: -name-specifiers 。


• :: A :: B :: F ，并且 B :: 和 A :: B ::
。这是一个不完整的描述。很难用简单的英语描述语法...



Related to this

I want to know what exactly is a nested name specifier? I looked up in the draft but I could understand the grammar as I haven't taken any Compiler Design classes yet.

void S(){}

struct S{
   S(){cout << 1;}
   void f(){}
   static const int x = 0;
}; 

int main(){ 
   struct S *p = new struct ::S;  
   p->::S::f();

   S::x;  

   ::S(); // Is ::S a nested name specifier?
   delete p;
} 

解决方案

::S is a qualified-id.

In the qualified-id ::S::f, S:: is a nested-name-specifier.

In informal terms¹, a nested-name-specifier is the part of the id that

• begins either at the very beginning of a qualified-id or after the initial scope resolution operator (::) if one appears at the very beginning of the id and
• ends with the last scope resolution operator in the qualified-id.

Very informally¹, an id is either a qualified-id or an unqualified-id. If the id is a qualified-id, it is actually composed of two parts: a nested-name specifier followed by an unqualified-id.

Given:

struct  A {
    struct B {
        void F();
    };
};

• A is an unqualified-id.
• ::A is a qualified-id but has no nested-name-specifier.
• A::B is a qualified-id and A:: is a nested-name-specifier.
• ::A::B is a qualified-id and A:: is a nested-name-specifier.
• A::B::F is a qualified-id and both B:: and A::B:: are nested-name-specifiers.
• ::A::B::F is a qualified-id and both B:: and A::B:: are nested-name-specifiers.

---

[1] This is quite an inexact description. It's hard to describe a grammar in plain English...

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