地图复杂查找操作 [英] map complex find operation

问题描述

我想执行以下操作：

定义字符串和任何类型的对象之间的映射（可能是一个列表，整数 - 任何东西）。

地图可以如下（值再次不重要）：

AAA / 123==> 1

AAA / ==> 2

BBB / ==> 3

CCC / *==> 4

CCC / 123==> 5

现在，我想找到给定以下字符串的正确值：

AAA / 123应该给出1.

AAA / 111应该给予2.

CCC / 111应该给予4.

CCC / 123应该给出5.

BBB / AAA / 123应该给予3.

I want to do the following:
Define a map between a string and any kind of object (may be a list, integer - anything).
The keys to the map can be as follow (the values are, again, not important):
"AAA/123" ==> 1
"AAA/" ==> 2
"BBB/" ==> 3
"CCC/*" ==> 4
"CCC/123" ==> 5
Now, the trick is I want to find the right values given the following strings:
"AAA/123" should give 1.
"AAA/111" should give 2.
"CCC/111" should give 4.
"CCC/123" should give 5.
"BBB/AAA/123" should give 3.

任何想法我怎么用C ++和STL / boost？

Any idea how I do that with C++ and possibly STL/boost ?

推荐答案

这是一个变体的litb答案（这在某些方面从答案列表中删除），可能会被删除*的工作：

Here's a variant of litb answer (which was somehow deleted from the answers list) which might work given the '*' is removed:

template<typename Map> typename Map::const_iterator
find_prefix(Map const& map, typename Map::key_type const& key)
{
    typename Map::const_iterator it = map.upper_bound(key);
    while (it != map.begin())
    {
        --it;
        if(key.substr(0, it->first.size()) == it->first)
            return it;
    }

    return map.end(); // map contains no prefix
}

我忘了添加使用它的代码：

I forgot to add the code that uses it:

std::map<std::string, int> smap;
smap["AAA/"] = 1;
smap["BBB/"] = 2;
smap["AAA/AA"] = 3;

find_prefix(smap, "AAA/AB")->second; // ==> 1
find_prefix(smap, "AAA/AA")->second; // ==> 3
find_prefix(smap, "BBB/AB")->second; // ==> 2
find_prefix(smap, "CCC/AB"); // ==> smap.end()

任何评论（感谢litb）？

any comment (and thanks to litb) ?

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