[英]To initialize a filtered_graph object in constructor after graph is defined in BOOST GRAPH
I have a query in initializing filtered_graph in boost. 我在初始化boost中的filter_graph有一个查询。
here is my code, 这是我的代码,
// predicate
template <typename TGraph>
struct edge_predicate
{
bool operator()(const typename boost::graph_traits<TGraph>::edge_descriptor& v) const
{
return true //testing purpose
}
};
// class
class A{
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, Node_Info, Edge_Info > Graph_t;
typedef boost::filtered_graph < Graph_t , edge_predicate > FilteredGraphType_t;
// members
Graph G;
FilteredGraphType_t FG() ; // empty filter graph ???
// constructor for A
template < ..typename list >
A ( ... input iterators list... )
{
fill the graph G with some values passed in constructor argument list.
// predicate
edge_predicate< Graph_t > EPred;
//filtered_graph
FilteredGraphType_t FG( G, EPred); // I am passing on edge predicate.
}
};
// member function:
FilteredGraphType_t& get_filtered_graph()
{
return FG;
}
Problem: 问题:
FG is a member of class A, and G is also a member of A. Initially G is empty object, so is FG I suppose,.. FG是A类的成员,G也是A的成员。最初,G是空对象,所以我想FG也是如此。
In constructor of A, I fill Graph G with my logic ( such as number of vertices, edges etc ). 在A的构造函数中,我用自己的逻辑(例如,顶点数,边数等)填充GraphG。 Now, I want to create a filter FG (which is member of class A) over graph G (after G is filled).
现在,我想在图G(填充G之后)上创建一个过滤器FG (它是A类的成员 )。
The reason I want this is that this filtered graph is passed as a reference to some other class constructor. 我想要这个的原因是,此筛选后的图形作为对其他类构造函数的引用传递。 This forces me to make FG as member of class A. ( I could create new instance of filter graph in constructor of A itself, but it wont serve the purpose of returning the reference to FG. )
这迫使我使FG成为类A的成员。(我可以在A本身的构造函数中创建过滤器图的新实例,但不会达到将引用返回给FG的目的。)
I hope it is clear. 我希望这很清楚。 please suggest
请建议
You can make your code compile and work OK. 您可以使代码编译并正常运行。 Try reorganizing the constructor as follows:
尝试按如下所示重新组织构造函数:
// constructor for A
template < ..typename list >
A ( ... input iterators list... )
: G() //calls constructor for G
, EPred(...) //some constructor for predicate
, FG( boost::make_filtered_graph(G, EPred) ) //creates your filtered graph
{
// fill the graph G with some values passed in constructor argument list.
}
The rest of code can remain unchanged. 其余代码可以保持不变。
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