Version 5.0 The LEDA User Manual

7.4 Maps ( map )
1. Definition
An instance M of the parameterized data type map is an injective mapping from
the data type I, called the index type of M, to the set of variables of data type E, called
the element type of M. I must be a pointer, item, or handle type or the type int. We use
M(i) to denote the variable indexed by i. All variables are initialized to xdef , an element
of E that is specified in the definition of M. A subset of I is designated as the domain of
M. Elements are added to dom(M) by the subscript operator; however, the domain may
also contain indices for which the access operator was never executed.
Related data types are d arrays, h arrays, and dictionaries.
#include < LEDA/core/map.h >
2. Types
map:: item
map:: index type
map:: element type
the item type.
the index type.
the element type.
3. Creation
map M;
map M(E x);
map M(E x, int table sz);
4. Operations
creates an injective function m from I to the set of unused
variables of type E, sets xdef to the default value of type E
(if E has no default value then xdef is set to an unspecified
element of E), and initializes M with m.
creates an injective function m from I to the set of unused
variables of type E, sets xdef to x, and initializes M with m.
as above, but uses an initial table size of table sz instead of
the default size 1.
E& M[const I& i] returns the variable M(i) and adds i to dom(M).
If M is a const-object then M(i) is read-only and
i is not added to dom(M).
bool M.defined(const I& i) returns true if i ∈ dom(M).
void M.clear( ) makes M empty.
void M.clear(const E& x) makes M empty and sets xdef to x.
void M.set default value(const E& x)
Iteration:
sets xdef to x.
forall(x, M) { “the entries M[i] with i ∈ dom(M) are successively assigned to x” }