C++ 一个字符串的代理类（String View)

最新推荐文章于 2025-07-08 10:42:53 发布

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最新推荐文章于 2025-07-08 10:42:53 发布 · 4.3k 阅读

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#c++

在学习muduo/base源码的时候看到一个StringPiece类，是个string view，记录下来。

关于string view，看http://stackoverflow.com/questions/20803826/what-is-string-view。

简单摘抄下来就是

The purpose of any and all kinds of “string reference” and “array reference” proposals is to avoid copying data which is already owned somewhere else and of which only a non-mutating view is required. The string_view in question is one such proposal; there were earlier ones called string_ref and array_ref, too.

The idea is always to store a pair of pointer-to-first-element and size of some existing data array or string.

string view解释过来就是个窗口，你通过这个窗口查看代理的字符串的内容，移动指针和改变长度就可以移动窗口，而且，自身不需要存储字符串，只读，不可修改，生命期应和代理的字符串一致。

muduo的StringPiece代码如下，个人做了一点修改：

class StringPiece {
public:
    StringPiece()
        : _ptr(nullptr),
          _length(0)
    {
    }

    StringPiece(const char* str)
        : _ptr(str),
          _length(strlen(_ptr))
    {
    }

    StringPiece(