[英]How to write standard C++ iterator?
I have the following simple Graph
class, where for each Node
, I store a set of outgoing Arcs
: 我有以下简单的Graph
类,其中对于每个Node
,我存储一组传出的Arcs
:
#include <iostream>
#include <vector>
#include <map>
#include <set>
struct Arc {
char label;
int targetNode;
};
struct Graph {
std::vector<int> nodes;
std::map< int, std::set<Arc*> > outgoingArcsPerNode;
};
How can I provide a standard C++ iterator
over all the arcs in the graph (order of iteration doesn't matter) that hides how the arcs are stored in the graph? 如何在图中的所有弧上提供标准C ++ iterator
(迭代次序无关紧要),隐藏弧如何存储在图中?
I would like to use it similar to the following: 我想使用它类似于以下内容:
int main() {
Graph g;
for (Graph::const_iterator it = g.arcsBegin(); it != g.arcsEnd(); ++it) {
Arc* a = *it;
}
}
I heard of boost::iterator
, but I find it confusing. 我听说过boost::iterator
,但我发现它令人困惑。 Maybe someone could give a hint how to use it in this case? 也许有人可以提示如何在这种情况下使用它?
If you don't want to use boost, have a look at what iterators must provide : STL documentation . 如果您不想使用boost,请查看迭代器必须提供的内容: STL文档 。
Otherwise, you may use boost iterator library . 否则,您可以使用boost迭代器库 。 See the iterator_facade tutorial which is very close to what you're asking. 请参阅iterator_facade教程 ,该教程非常接近您的要求。
Create class which has two iterators inside: one over map and another over set. 创建内部有两个迭代器的类:一个在地图上,另一个在集合上。
Each ++ is applied to set iterator. 每个++都应用于设置迭代器。 When it reaches the end, increment map iterator and reinitialize set iterator. 当它到达结尾时,增加map迭代器并重新初始化set iterator。
Also you can use boost::iterator_facade - it will not help to implement algorithm of the iteration, but will minimize your effort on making your iterator compatible to STL expectations... 您也可以使用boost :: iterator_facade - 它将无助于实现迭代算法,但会最大限度地减少您使迭代器与STL期望兼容的努力......
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