Forward Container
 |
 |
Category: containers |
Component type: concept |
Description
A Forward Container is a Container whose elements are
arranged in a definite order: the ordering will not change
spontaneously from iteration to iteration. The requirement of a
definite ordering allows the definition of element-by-element equality
(if the container's element type is Equality Comparable)
and of lexicographical ordering
(if the container's element type is LessThan Comparable).
Iterators into a Forward Container
satisfy the forward iterator requirements; consequently, Forward
Containers support multipass algorithms and allow multiple iterators
into the same container to be active at the same time.
Refinement of
Container, EqualityComparable, LessThanComparable
Associated types
No additional types beyond those defined in Container. However,
the requirements for the iterator type are strengthened: the iterator
type must be a model of Forward Iterator.
Notation
X
|
A type that is a model of Forward Container
|
a, b
|
Object of type X
|
T
|
The value type of X
|
Definitions
Valid expressions
In addition to the expressions defined in Container,
EqualityComparable, and LessThanComparable,
the following expressions must be valid.
Expression semantics
Semantics of an expression is defined only where it is not defined in
Container, EqualityComparable, or LessThanComparable, or
where there is additional information.
Name
|
Expression
|
Precondition
|
Semantics
|
Postcondition
|
Equality
|
a == b
|
|
Returns true if a.size() == b.size() and if each element of a
compares equal to the corresponding element of b. Otherwise
returns false.
|
|
Less
|
a < b
|
|
Equivalent to lexicographical_compare(a,b)
|
|
Complexity guarantees
The equality and inequality operations are linear in the
container's size.
Invariants
Ordering
|
Two different iterations through a forward container will access
its elements in the same order, providing that there have been
no intervening mutative operations.
|
Models
Notes
See also
The iterator overview, Forward Iterator, Sequence
Copyright ©
1996 Silicon Graphics, Inc. All Rights Reserved.
TrademarkInformation