Boost C++ Libraries

Concept InputIterator

InputIterator

Description

An input iterator is an iterator that can read through a sequence of values. It is single-pass (old values of the iterator cannot be re-used), and read-only.

An input iterator represents a position in a sequence. Therefore, the iterator can point into the sequence (returning a value when dereferenced and being incrementable), or be off-the-end (and not dereferenceable or incrementable).

Refinement of

Associated types

value_type
```
std::iterator_traits<Iter>::value_type
```
The value type of the iterator (not necessarily what *i returns)
difference_type
```
std::iterator_traits<Iter>::difference_type
```
The difference type of the iterator

category

std::iterator_traits<Iter>::iterator_category

The category of the iterator

Notation

Iter: A type playing the role of iterator-type in the InputIterator concept.
i, j: Objects of type Iter
x: Object of type value_type

Type expressions

Category tag: category must be derived from std::input_iterator_tag, a model of DefaultConstructible, and a model of CopyConstructible.
Value type copy constructibility: value_type must be a model of CopyConstructible.
Difference type properties: difference_type must be a model of SignedInteger.

Valid expressions

Name	Expression	Type	Precondition	Semantics	Postcondition
Dereference	*i	Convertible to value_type	`i` is incrementable (not off-the-end)
Preincrement	++i	Iter &	`i` is incrementable (not off-the-end)
Postincrement	i++		`i` is incrementable (not off-the-end)	Equivalent to `(void)(++i)`	`i` is dereferenceable or off-the-end
Postincrement and dereference	*i++	Convertible to value_type	`i` is incrementable (not off-the-end)	Equivalent to `{value_type t = *i; ++i; return t;}`	`i` is dereferenceable or off-the-end

Complexity

All iterator operations must take amortized constant time.

Models

std::istream_iterator

This product includes software developed at the University of Notre Dame and the Pervasive Technology Labs at Indiana University. For technical information contact Andrew Lumsdaine at the Pervasive Technology Labs at Indiana University. For administrative and license questions contact the Advanced Research and Technology Institute at 351 West 10th Street. Indianapolis, Indiana 46202, phone 317-278-4100, fax 317-274-5902.

Some concepts based on versions from the MTL draft manual and Boost Graph and Property Map documentation, the SGI Standard Template Library documentation and the Hewlett-Packard STL, under the following license:

Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Silicon Graphics makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.