使用非键类型在集中进行有效搜索 [英] Efective search in set with non-key type

问题描述

我有类似的数据结构：

struct Data { std::string id; Blob data; };

现在我可以使用 std :: map 存储结构并通过ID搜索，但是我搜索一个方法来实现与 std :: set 相同的事情（因为我真的不需要分离ID和结构）。

Now I can use a std::map to store the structure and search by ID, but I searching for a way to achieve the same thing with a std::set (since I don't really need to separate the ID and the structure).

std :: set :: find 当然采用键类型作为参数，所以我可以这样做（使用适当的构造函数）：

std::set::find of course takes the key type as a parameter, so I could do something like this (with the appropriate constructor):

set<Data> x; x.find(Data("some_id"));

但我想避免这种情况。它需要有一个允许ID没有数据的构造函数，加上我不喜欢构造一个对象，只是用它作为搜索的键。

But I would like to avoid this if possible. It would require having a constructor that allows ID without data, plus I don't really like constructing an object, just to use it as a key for search.

问题是：有更好的方法吗？

So my question is: Is there a better way?

推荐答案

除非开销是明显不可接受的，我会去 std :: map< std :: string，Data *> 或者可能 std :: map< std :: string，boost :: shared_ptr< Data> > ，假设您无权访问提供shared_ptr的本地编译器。

Unless the overhead is demonstrably unacceptable I'd go for std::map<std::string, Data *>, or possibly std::map<std::string, boost::shared_ptr<Data> >, assuming you don't have access to a compiler that provides shared_ptr natively.

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