Forward Sequence

Description

A Forward Sequence is an MPL concept representing a compile-time sequence of elements. Sequence elements are types, and are accessible through Iterators. The begin and end metafunctions provide iterators delimiting the range of the sequence elements. A sequence guarantees that its elements are arranged in a definite, but possibly unspecified, order. Every MPL sequence is a Forward Sequence.

Definitions

The size of a sequence is the number of elements it contains. The size is a nonnegative number.
A sequence is empty if its size is zero.

Expression requirements

For any Forward Sequence s the following expressions must be valid:

Expression	Type	Complexity
begin<s>::type	Forward Iterator	Amortized constant time
end<s>::type	Forward Iterator	Amortized constant time
size<s>::type	Integral Constant	Unspecified
empty<s>::type	Boolean Integral Constant	Constant time
front<s>::type	Any type	Amortized constant time

Expression semantics

Expression	Semantics
begin<s>::type	An iterator to the first element of the sequence; see begin.
end<s>::type	A past-the-end iterator to the sequence; see end.
size<s>::type	The size of the sequence; see size.
empty<s>::type	A boolean Integral Constant c such that c::value == true if and only if the sequence is empty; see empty.
front<s>::type	The first element in the sequence; see front.

Invariants

For any Forward Sequence s the following invariants always hold:

[begin<s>::type, end<s>::type) is always a valid range.
An algorithm that iterates through the range [begin<s>::type, end<s>::type) will pass through every element of s exactly once.
begin<s>::type is identical to end<s>::type if and only if s is empty.
Two different iterations through s will access its elements in the same order.

Forward Sequence

Forward Sequence

Description

Definitions

Expression requirements

Expression semantics

Invariants

Models

See also