Adaptor Classes for Graphs
[Graph Structures]

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Detailed Description

The main parts of LEMON are the different graph structures, generic graph algorithms, graph concepts which couple these, and graph adaptors. While the previous notions are more or less clear, the latter one needs further explanation. Graph adaptors are graph classes which serve for considering graph structures in different ways.

A short example makes this much clearer. Suppose that we have an instance g of a directed graph type say ListGraph and an algorithm

 template<typename Graph> int algorithm(const Graph&); 

is needed to run on the reversed oriented graph. It may be expensive (in time or in memory usage) to copy g with the reversed orientation. In this case, an adaptor class is used, which (according to LEMON graph concepts) works as a graph. The adaptor uses the original graph structure and graph operations when methods of the reversed oriented graph are called. This means that the adaptor have minor memory usage, and do not perform sophisticated algorithmic actions. The purpose of it is to give a tool for the cases when a graph have to be used in a specific alteration. If this alteration is obtained by a usual construction like filtering the edge-set or considering a new orientation, then an adaptor is worthwhile to use. To come back to the reversed oriented graph, in this situation

 template<typename Graph> class RevGraphAdaptor; 

template class can be used. The code looks as follows

   ListGraph g;
   RevGraphAdaptor<ListGraph> rga(g);
   int result=algorithm(rga);

After running the algorithm, the original graph g is untouched. This techniques gives rise to an elegant code, and based on stable graph adaptors, complex algorithms can be implemented easily.

In flow, circulation and bipartite matching problems, the residual graph is of particular importance. Combining an adaptor implementing this, shortest path algorithms and minimum mean cycle algorithms, a range of weighted and cardinality optimization algorithms can be obtained. For other examples, the interested user is referred to the detailed documentation of particular adaptors.

The behavior of graph adaptors can be very different. Some of them keep capabilities of the original graph while in other cases this would be meaningless. This means that the concepts that they are models of depend on the graph adaptor, and the wrapped graph(s). If an edge of rga is deleted, this is carried out by deleting the corresponding edge of g, thus the adaptor modifies the original graph. But for a residual graph, this operation has no sense. Let us stand one more example here to simplify your work. RevGraphAdaptor has constructor

   RevGraphAdaptor(Graph& _g);

This means that in a situation, when a const ListGraph& reference to a graph is given, then it have to be instantiated with Graph=const ListGraph.

   int algorithm1(const ListGraph& g) {
   RevGraphAdaptor<const ListGraph> rga(g);
   return algorithm2(rga);
   }

Classes
class	BpUGraphAdaptorBase< _BpUGraph >
	Base type for the Bipartite Undirected Graph Adaptors. More...
class	BpUGraphAdaptor< _BpUGraph >
	Trivial Bipartite Undirected Graph Adaptor. More...
class	SwapBpUGraphAdaptor< _BpUGraph >
	Bipartite graph adaptor which swaps the two nodeset. More...
class	MatchingBpUGraphAdaptor< _BpUGraph, _ANMatchingMap, _BNMatchingMap >
	Bipartite graph adaptor to implement matching algorithms. More...
class	GraphAdaptor< _Graph >
	Trivial Graph Adaptor. More...
class	RevGraphAdaptor< _Graph >
	A graph adaptor which reverses the orientation of the edges. More...
class	SubGraphAdaptor< _Graph, NodeFilterMap, EdgeFilterMap, checked >
	A graph adaptor for hiding nodes and edges from a graph. More...
class	NodeSubGraphAdaptor< Graph, NodeFilterMap, checked >
	An adaptor for hiding nodes from a graph. More...
class	EdgeSubGraphAdaptor< Graph, EdgeFilterMap >
	An adaptor for hiding edges from a graph. More...
class	UndirGraphAdaptor< _Graph >
	An undirected graph is made from a directed graph by an adaptor. More...
class	ResGraphAdaptor< Graph, Number, CapacityMap, FlowMap, Tol >
	An adaptor for composing the residual graph for directed flow and circulation problems. More...
class	ErasingFirstGraphAdaptor< _Graph, FirstOutEdgesMap >
	For blocking flows. More...
class	SplitGraphAdaptor< _Graph >
	Split graph adaptor class. More...
class	UGraphAdaptor< _UGraph >
	Trivial undirected graph adaptor. More...
class	SubUGraphAdaptor< _UGraph, NodeFilterMap, UEdgeFilterMap, checked >
	A graph adaptor for hiding nodes and edges from an undirected graph. More...
class	NodeSubUGraphAdaptor< _UGraph, NodeFilterMap, checked >
	An adaptor for hiding nodes from an undirected graph. More...
class	EdgeSubUGraphAdaptor< _UGraph, UEdgeFilterMap >
	An adaptor for hiding undirected edges from an undirected graph. More...
class	DirUGraphAdaptor< _Graph, DirectionMap >
	A directed graph is made from an undirected graph by an adaptor. More...
Files
file	bpugraph_adaptor.h
	Several graph adaptors.
file	graph_adaptor.h
	Several graph adaptors.
file	ugraph_adaptor.h
	Several graph adaptors.