Definition
An instance of the data type edge_map<E> is a map for the edges of a graph G, i.e., equivalent to map<edge,E> (cf. Maps). It can be used as a dynamic variant of the data type edge_array (cf. Edge Arrays). New: Since edge_map<E> is derived from edge_array<E> edge maps can be passed (by reference) to functions with edge array parameters. In particular, all LEDA graph algorithms expecting an edge_array<E>& argument can be passed an edge_map<E>& instead.
#include < LEDA/edge _map.h >
Creation
| edge_map<E> | M | introduces a variable M of type edge_map<E> and initializes it to the map with empty domain. |
| edge_map<E> | M(graph G) | introduces a variable M of type edge_map<E> and initializes it with a mapping m from the set of all edges of G into the set of variables of type E. The variables in the range of m are initialized by a call of the default constructor of type E. |
| edge_map<E> | M(graph G, E x) | introduces a variable M of type edge_map<E> and initializes it with a mapping m from the set of all edges of G into the set of variables of type E. The variables in the range of m are initialized with a copy of x. |
Operations
| graph | M.get_graph() | returns a reference to the graph of M. |
| void | M.init() | makes M a edge map with empty domain. |
| void | M.init(graph G) | makes M a mapping m from the set of all edges of G into the set of variables of type E. The variables in the range of m are initialized by a call of the default constructor of type E. |
| void | M.init(graph G, E x) | makes M a mapping m from the set of all edges of G into the set of variables of type E. The variables in the range of m are initialized with a copy of x. |
| E& | M[edge e] | returns the variable M(v). |
Implementation
Edge maps are implemented by an efficient hashing method based on the internal numbering of the edges. An access operation takes expected time O(1).