blob: 5a706c5acb2886144e41f6245a6901c09a405a33 [file] [log] [blame]
[/==============================================================================
Copyright (C) 2001-2007 Joel de Guzman, Dan Marsden, Tobias Schwinger
Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
===============================================================================/]
[section Iterator]
Like __mpl__ and __stl__, iterators are a fundamental concept in Fusion.
As with __mpl__ and __stl__ iterators describe positions, and
provide access to data within an underlying __sequence__.
[heading Header]
#include <boost/fusion/iterator.hpp>
#include <boost/fusion/include/iterator.hpp>
[section Concepts]
Fusion iterators are divided into different traversal categories.
__forward_iterator__ is the most basic concept. __bidirectional_iterator__
is a refinement of __forward_iterator__. __random_access_iterator__ is a
refinement of __bidirectional_iterator__. __associative_iterator__ is a
refinement of __forward_iterator__, __bidirectional_iterator__ or
__random_access_iterator__.
[section Forward Iterator]
[heading Description]
A Forward Iterator traverses a __sequence__ allowing movement in only one direction through
it's elements, one element at a time.
[variablelist Notation
[[`i`, `j`] [Forward Iterators]]
[[`I`, `J`] [Forward Iterator types]]
[[`M`] [An __mpl__ integral constant]]
[[`N`] [An integral constant]]
]
[heading Expression requirements]
A type models Forward Iterator if, in addition to being CopyConstructable,
the following expressions are valid:
[table
[[Expression] [Return type] [Runtime Complexity]]
[[`__next__(i)`] [__forward_iterator__] [Constant]]
[[`i == j`] [Convertible to bool] [Constant]]
[[`i != j`] [Convertible to bool] [Constant]]
[[`__advance_c__<N>(i)`] [__forward_iterator__] [Constant]]
[[`__advance__<M>(i)`] [__forward_iterator__] [Constant]]
[[`__distance__(i, j)`] [`__result_of_distance__<I, J>::type`][Constant]]
[[`__deref__(i)`] [`__result_of_deref__<I>::type`] [Constant]]
[[`*i`] [`__result_of_deref__<I>::type`] [Constant]]
]
[heading Meta Expressions]
[table
[[Expression] [Compile Time Complexity]]
[[`__result_of_next__<I>::type`] [Amortized constant time]]
[[`__result_of_equal_to__<I, J>::type`] [Amortized constant time]]
[[`__result_of_advance_c__<I, N>::type`] [Linear]]
[[`__result_of_advance__<I ,M>::type`] [Linear]]
[[`__result_of_distance__<I ,J>::type`] [Linear]]
[[`__result_of_deref__<I>::type`] [Amortized constant time]]
[[`__result_of_value_of__<I>::type`] [Amortized constant time]]
]
[heading Expression Semantics]
[
table
[[Expression] [Semantics]]
[[`__next__(i)`] [An iterator to the element following `i`]]
[[`i == j`] [Iterator equality comparison]]
[[`i != j`] [Iterator inequality comparison]]
[[`__advance_c__<N>(i)`] [An iterator n elements after `i` in the sequence]]
[[`__advance__<M>(i)`] [Equivalent to `advance_c<M::value>(i)`]]
[[`__distance__(i, j)`] [The number of elements between `i` and `j`]]
[[`__deref__(i)`] [The element at position`i`]]
[[`*i`] [Equivalent to `deref(i)`]]
]
[heading Invariants]
The following invariants always hold:
* `!(i == j) == (i != j)`
* `__next__(i) == __advance_c__<1>(i)`
* `__distance__(i, __advance_c__<N>(i)) == N`
* Using `__next__` to traverse the sequence will never return to a previously seen position
* `__deref__(i)` is equivalent to `*i`
* If `i == j` then `*i` is equivalent to `*j`
[heading Models]
* __std_pair__ iterator
* __boost_array__ iterator
* __vector__ iterator
* __cons__ iterator
* __list__ iterator
* __set__ iterator
* __map__ iterator
* __single_view__ iterator
* __filter_view__ iterator
* __iterator_range__ iterator
* __joint_view__ iterator
* __transform_view__ iterator
* __reverse_view__ iterator
[endsect]
[section Bidirectional Iterator]
[heading Description]
A Bidirectional Iterator traverses a __sequence__ allowing movement in either direction one
element at a time.
[variablelist Notation
[[`i`] [A Bidirectional Iterator]]
[[`I`] [A Bidirectional Iterator type]]
[[`M`] [An __mpl__ integral constant]]
[[`N`] [An integral constant]]
]
[heading Refinement of]
__forward_iterator__
[heading Expression requirements]
In addition to the requirements defined in __forward_iterator__,
the following expressions must be valid:
[table
[[Expression] [Return type] [Runtime Complexity]]
[[`__next__(i)`] [__bidirectional_iterator__] [Constant]]
[[`__prior__(i)`] [__bidirectional_iterator__] [Constant]]
[[`__advance_c__<N>(i)`] [__bidirectional_iterator__] [Constant]]
[[`__advance__<M>(i)`] [__bidirectional_iterator__] [Constant]]
]
[heading Meta Expressions]
[table
[[Expression] [Compile Time Complexity]]
[[`__result_of_prior__<I>::type`] [Amortized constant time]]
]
[heading Expression Semantics]
The semantics of an expression are defined only where they differ from, or are not defined
in __forward_iterator__
[table
[[Expression] [Semantics]]
[[`__prior__(i)`] [An iterator to the element preceding `i`]]
]
[heading Invariants]
In addition to the invariants of __forward_iterator__,
the following invariants always hold:
* `__prior__(__next__(i)) == i && __prior__(__next__(i)) == __next__(__prior__(i))`
* `__prior__(i) == __advance_c__<-1>(i)`
* Using `__prior__` to traverse a sequence will never return a previously seen position
[heading Models]
* __std_pair__ iterator
* __boost_array__ iterator
* __vector__ iterator
* __iterator_range__ (where adapted sequence is a __bidirectional_sequence__)
* __transform_view__ (where adapted sequence is a __bidirectional_sequence__)
* __reverse_view__
[endsect]
[section Random Access Iterator]
[heading Description]
A Random Access Iterator traverses a __sequence__ moving in either direction,
permitting efficient arbitrary distance movements back and forward through the
sequence.
[variablelist Notation
[[`i`, `j`] [Random Access Iterators]]
[[`I`, `J`] [Random Access Iterator types]]
[[`M`] [An __mpl__ integral constant]]
[[`N`] [An integral constant]]
]
[heading Refinement of]
__bidirectional_iterator__
[heading Expression requirements]
In addition to the requirements defined in __bidirectional_iterator__,
the following expressions must be valid:
[table
[[Expression] [Return type] [Runtime Complexity]]
[[`__next__(i)`] [__random_access_iterator__] [Constant]]
[[`__prior__(i)`] [__random_access_iterator__] [Constant]]
[[`__advance_c__<N>(i)`] [__random_access_iterator__] [Constant]]
[[`__advance__<M>(i)`] [__random_access_iterator__] [Constant]]
]
[heading Meta Expressions]
[table
[[Expression] [Compile Time Complexity]]
[[`__result_of_advance_c__<I, N>::type`] [Amortized constant time]]
[[`__result_of_advance__<I, M>::type`] [Amortized constant time]]
[[`__result_of_distance__<I ,J>::type`] [Amortized constant time]]
]
[heading Models]
* __vector__ iterator
* __std_pair__ iterator
* __boost_array__ iterator
* __iterator_range__ iterator (where adapted sequence is a __random_access_sequence__)
* __transform_view__ iterator (where adapted sequence is a __random_access_sequence__)
* __reverse_view__ iterator (where adapted sequence is a __random_access_sequence__)
[endsect]
[section Associative Iterator]
[heading Description]
An Associative Iterator provides additional semantics to obtain the properties
of the element of an associative forward, bidirectional or random access sequence.
[variablelist Notation
[[`i`] [Associative Iterator]]
[[`I`] [Associative Iterator type]]
]
[heading Refinement of]
__forward_iterator__, __bidirectional_iterator__ or __random_access_iterator__
[heading Expression requirements]
In addition to the requirements defined in __forward_iterator__,
__bidirectional_iterator__ or __random_access_iterator__ the following
expressions must be valid:
[table
[[Expression] [Return type] [Runtime Complexity]]
[[`__deref_data__(i)`][`__result_of_deref_data__<I>::type`][Constant]]
]
[heading Meta Expressions]
[table
[[Expression] [Compile Time Complexity]]
[[`__result_of_key_of__<I>::type`][Amortized constant time]]
[[`__result_of_value_of_data__<I>::type`][Amortized constant time]]
[[`__result_of_deref_data__<I>::type`][Amortized constant time]]
]
[heading Models]
* __map__ iterator
* __set__ iterator
* __filter_view__ iterator (where adapted sequence is an __associative_sequence__ and a __forward_sequence__)
* __iterator_range__ iterator (where adapted iterators are __associative_iterator__\ s)
* __joint_view__ iterator (where adapted sequences are __associative_sequence__\ s and __forward_sequence__\ s)
* __reverse_view__ iterator (where adapted sequence is an __associative_sequence__ and a __bidirectional_sequence__)
[endsect]
[endsect]
[section Functions]
Fusion provides functions for manipulating iterators, analogous to the similar functions
from the __mpl__ library.
[section deref]
[heading Description]
Deferences an iterator.
[heading Synopsis]
template<
typename I
>
typename __result_of_deref__<I>::type deref(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__deref__(i);
[*Return type]: `__result_of_deref__<I>::type`
[*Semantics]: Dereferences the iterator `i`.
[heading Header]
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/include/deref.hpp>
[heading Example]
typedef __vector__<int,int&> vec;
int i(0);
vec v(1,i);
assert(__deref__(__begin__(v)) == 1);
assert(__deref__(__next__(__begin__(v))) == 0);
assert(&(__deref__(__next__(__begin__(v)))) == &i);
[endsect]
[section next]
[heading Description]
Moves an iterator 1 position forwards.
[heading Synopsis]
template<
typename I
>
typename __result_of_next__<I>::type next(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
next(i);
[*Return type]: A model of the same iterator concept as `i`.
[*Semantics]: Returns an iterator to the next element after `i`.
[heading Header]
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/include/next.hpp>
[heading Example]
typedef __vector__<int,int,int> vec;
vec v(1,2,3);
assert(__deref__(__begin__(v)) == 1);
assert(__deref__(__next__(__begin__(v))) == 2);
assert(__deref__(__next__(__next__(__begin__(v)))) == 3);
[endsect]
[section prior]
[heading Description]
Moves an iterator 1 position backwards.
[heading Synopsis]
template<
typename I
>
typename __result_of_prior__<I>::type prior(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __bidirectional_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__prior__(i);
[*Return type]: A model of the same iterator concept as `i`.
[*Semantics]: Returns an iterator to the element prior to `i`.
[heading Header]
#include <boost/fusion/iterator/prior.hpp>
#include <boost/fusion/include/prior.hpp>
[heading Example]
typedef __vector__<int,int> vec;
vec v(1,2);
assert(__deref__(__next__(__begin__(v))) == 2);
assert(__deref__(__prior__(__next__(__begin__(v)))) == 1);
[endsect]
[section distance]
[heading Description]
Returns the distance between 2 iterators.
[heading Synopsis]
template<
typename I,
typename J
>
typename __result_of_distance__<I, J>::type distance(I const& i, J const& j);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`, `j`] [Models of __forward_iterator__ into the same sequence] [The start and end points of the distance to be measured]]
]
[heading Expression Semantics]
__distance__(i,j);
[*Return type]: `int`
[*Semantics]: Returns the distance between iterators `i` and `j`.
[heading Header]
#include <boost/fusion/iterator/distance.hpp>
#include <boost/fusion/include/distance.hpp>
[heading Example]
typedef __vector__<int,int,int> vec;
vec v(1,2,3);
assert(__distance__(__begin__(v), __next__(__next__(__begin__(v)))) == 2);
[endsect]
[section advance]
[heading Description]
Moves an iterator by a specified distance.
[heading Synopsis]
template<
typename I,
typename M
>
typename __result_of_advance__<I, M>::type advance(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __forward_iterator__] [Iterator to move relative to]]
[[`N`] [An __mpl_integral_constant__] [Number of positions to move]]
]
[heading Expression Semantics]
__advance__<M>(i);
[*Return type]: A model of the same iterator concept as `i`.
[*Semantics]: Returns an iterator to the element `M` positions from `i`. If `i` is a __bidirectional_iterator__ then `M` may be negative.
[heading Header]
#include <boost/fusion/iterator/advance.hpp>
#include <boost/fusion/include/advance.hpp>
[heading Example]
typedef __vector__<int,int,int> vec;
vec v(1,2,3);
assert(__deref__(__advance__<mpl::int_<2> >(__begin__(v))) == 3);
[endsect]
[section advance_c]
[heading Description]
Moves an iterator by a specified distance.
[heading Synopsis]
template<
typename I,
int N
>
typename __result_of_advance_c__<I, N>::type advance_c(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __forward_iterator__] [Iterator to move relative to]]
[[`N`] [Integer constant] [Number of positions to move]]
]
[heading Expression Semantics]
__advance_c__<N>(i);
[*Return type]: A model of the same iterator concept as `i`.
[*Semantics]: Returns an iterator to the element `N` positions from `i`. If `i` is a __bidirectional_iterator__ then `N` may be negative.
[heading Header]
#include <boost/fusion/iterator/advance.hpp>
#include <boost/fusion/include/advance.hpp>
[heading Example]
typedef __vector__<int,int,int> vec;
vec v(1,2,3);
assert(__deref__(__advance_c__<2>(__begin__(v))) == 3);
[endsect]
[section deref_data]
[heading Description]
Deferences the data property associated with the element referenced by an associative iterator.
[heading Synopsis]
template<
typename I
>
typename __result_of_deref_data__<I>::type deref(I const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __associative_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__deref_data__(i);
[*Return type]: `__result_of_deref_data__<I>::type`
[*Semantics]: Dereferences the data property associated with the element referenced by an associative iterator `i`.
[heading Header]
#include <boost/fusion/iterator/deref_data.hpp>
#include <boost/fusion/include/deref_data.hpp>
[heading Example]
typedef __map__<__pair__<float,int&> > map;
int i(0);
map m(1.0f,i);
assert(__deref_data__(__begin__(m)) == 0);
assert(&(__deref_data__(__begin__(m))) == &i);
[endsect]
[endsect]
[section Operator]
Overloaded operators are provided to provide a more natural syntax for dereferencing iterators, and comparing them for equality.
[section:operator_unary_star Operator *]
[heading Description]
Dereferences an iterator.
[heading Synopsis]
template<
typename I
>
typename __result_of_deref__<I>::type operator*(__unspecified__<I> const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
*i
[*Return type]: Equivalent to the return type of `__deref__(i)`.
[*Semantics]: Equivalent to `__deref__(i)`.
[heading Header]
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/include/deref.hpp>
[heading Example]
typedef __vector__<int,int&> vec;
int i(0);
vec v(1,i);
assert(*__begin__(v) == 1);
assert(*__next__(__begin__(v)) == 0);
assert(&(*__next__(__begin__(v))) == &i);
[endsect]
[section:operator_equality Operator ==]
[heading Description]
Compares 2 iterators for equality.
[heading Synopsis]
template<
typename I,
typename J
>
__unspecified__ operator==(I const& i, J const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`, `j`] [Any fusion iterators] [Operation's arguments]]
]
[heading Expression Semantics]
i == j
[*Return type]: Convertible to `bool`.
[*Semantics]: Equivalent to `__result_of_equal_to__<I,J>::value` where `I` and `J` are the types of `i` and `j` respectively.
[heading Header]
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/include/equal_to.hpp>
[endsect]
[section:operator_inequality Operator !=]
[heading Description]
Compares 2 iterators for inequality.
[heading Synopsis]
template<
typename I,
typename J
>
__unspecified__ operator==(I const& i, J const& i);
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`i`, `j`] [Any fusion iterators] [Operation's arguments]]
]
[heading Expression Semantics]
[*Return type]: Convertible to `bool`.
[*Semantics]: Equivalent to `!__result_of_equal_to__<I,J>::value` where `I` and `J` are the types of `i` and `j` respectively.
[heading Header]
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/include/equal_to.hpp>
[endsect]
[endsect]
[section Metafunctions]
[section value_of]
[heading Description]
Returns the type stored at the position of an iterator.
[heading Synopsis]
template<
typename I
>
struct value_of
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_value_of__<I>::type
[*Return type]: Any type
[*Semantics]: Returns the type stored in a sequence at iterator position `I`.
[heading Header]
#include <boost/fusion/iterator/value_of.hpp>
#include <boost/fusion/include/value_of.hpp>
[heading Example]
typedef __vector__<int,int&,const int&> vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_next__<first>::type second;
typedef __result_of_next__<second>::type third;
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<first>::type, int>));
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<second>::type, int&>));
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<third>::type, const int&>));
[endsect]
[section deref]
[heading Description]
Returns the type that will be returned by dereferencing an iterator.
[heading Synposis]
template<
typename I
>
struct deref
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_deref__<I>::type
[*Return type]: Any type
[*Semantics]: Returns the result of dereferencing an iterator of type `I`.
[heading Header]
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/include/deref.hpp>
[heading Example]
typedef __vector__<int,int&> vec;
typedef const vec const_vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_next__<first>::type second;
typedef __result_of_begin__<const_vec>::type const_first;
typedef __result_of_next__<const_first>::type const_second;
BOOST_MPL_ASSERT((boost::is_same<__result_of_deref__<first>::type, int&>));
BOOST_MPL_ASSERT((boost::is_same<__result_of_deref__<second>::type, int&>));
[endsect]
[section next]
[heading Description]
Returns the type of the next iterator in a sequence.
[heading Synposis]
template<
typename I
>
struct next
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __forward_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_next__<I>::type
[*Return type]: A model of the same iterator concept as `I`.
[*Semantics]: Returns an iterator to the next element in the sequence after `I`.
[heading Header]
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/include/next.hpp>
[heading Example]
typedef __vector__<int,double> vec;
typedef __result_of_next__<__result_of_begin__<vec>::type>::type second;
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<second>::type, double>));
[endsect]
[section prior]
[heading Description]
Returns the type of the previous iterator in a sequence.
[heading Synopsis]
template<
typename I
>
struct prior
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __bidirectional_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_prior__<I>::type
[*Return type]: A model of the same iterator concept as `I`.
[*Semantics]: Returns an iterator to the previous element in the sequence before `I`.
[heading Header]
#include <boost/fusion/iterator/prior.hpp>
#include <boost/fusion/include/prior.hpp>
[heading Example]
typedef __vector__<int,double> vec;
typedef __result_of_next__<__result_of_begin__<vec>::type>::type second;
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<second>::type, double>));
typedef __result_of_prior__<second>::type first;
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of__<first>::type, int>));
[endsect]
[section equal_to]
[heading Description]
Returns a true-valued __mpl_integral_constant__ if `I` and `J` are equal.
[heading Synopsis]
template<
typename I,
typename J
>
struct equal_to
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`, `J`] [Any fusion iterators] [Operation's arguments]]
]
[heading Expression Semantics]
__result_of_equal_to__<I, J>::type
[*Return type]: A model of __mpl_integral_constant__.
[*Semantics]: Returns `boost::mpl::true_` if `I` and `J` are iterators to the same position. Returns `boost::mpl::false_` otherwise.
[heading Header]
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/include/equal_to.hpp>
[heading Example]
typedef __vector__<int,double> vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_end__<vec>::type last;
BOOST_MPL_ASSERT((__result_of_equal_to__<first, first>));
BOOST_MPL_ASSERT_NOT((__result_of_equal_to__<first,last>));
[endsect]
[section distance]
[heading Description]
Returns the distance between two iterators.
[heading Synopsis]
template<
typename I,
typename J
>
struct distance
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`, `J`] [Models of __forward_iterator__ into the same sequence] [The start and end points of the distance to be measured]]
]
[heading Expression Semantics]
__result_of_distance__<I, J>::type
[*Return type]: A model of __mpl_integral_constant__.
[*Semantics]: Returns the distance between iterators of types `I` and `J`.
[heading Header]
#include <boost/fusion/iterator/distance.hpp>
#include <boost/fusion/include/distance.hpp>
[heading Example]
typedef __vector__<int,double,char> vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_next__<first>::type second;
typedef __result_of_next__<second>::type third;
typedef __result_of_distance__<first,third>::type dist;
BOOST_MPL_ASSERT_RELATION(dist::value, ==, 2);
[endsect]
[section advance]
[heading Description]
Moves an iterator a specified distance.
[heading Synopsis]
template<
typename I,
typename M
>
struct advance
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __forward_iterator__] [Iterator to move relative to]]
[[`M`] [Model of __mpl_integral_constant__] [Number of positions to move]]
]
[heading Expression Semantics]
__result_of_advance__<I,M>::type
[*Return type]: A model of the same iterator concept as `I`.
[*Semantics]: Returns an iterator a distance `M` from `I`. If `I` is a __bidirectional_iterator__ then `M` may be negative.
[heading Header]
#include <boost/fusion/iterator/advance.hpp>
#include <boost/fusion/include/advance.hpp>
[heading Example]
typedef __vector__<int,double,char> vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_next__<first>::type second;
typedef __result_of_next__<second>::type third;
BOOST_MPL_ASSERT((__result_of_equal_to__<__result_of_advance__<first, boost::mpl::int_<2> >::type, third>));
[endsect]
[section advance_c]
[heading Description]
Moves an iterator by a specified distance.
[heading Synopsis]
template<
typename I,
int N
>
struct advance_c
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __forward_iterator__] [Iterator to move relative to]]
[[`N`] [Integer constant] [Number of positions to move]]
]
[heading Expression Semantics]
__result_of_advance_c__<I, N>::type
[*Return type]: A model of the same iterator concept as `I`.
[*Semantics]: Returns an iterator a distance `N` from `I`. If `I` is a __bidirectional_iterator__ then `N` may be negative. Equivalent to `__result_of_advance__<I, boost::mpl::int_<N> >::type`.
[heading Header]
#include <boost/fusion/iterator/advance.hpp>
#include <boost/fusion/include/advance.hpp>
[heading Example]
typedef __vector__<int,double,char> vec;
typedef __result_of_begin__<vec>::type first;
typedef __result_of_next__<first>::type second;
typedef __result_of_next__<second>::type third;
BOOST_MPL_ASSERT((__result_of_equal_to__<__result_of_advance_c__<first, 2>::type, third>));
[endsect]
[section key_of]
[heading Description]
Returns the key type associated with the element referenced by an associative iterator.
[heading Synopsis]
template<
typename I
>
struct key_of
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __associative_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_key_of__<I>::type
[*Return type]: Any type
[*Semantics]: Returns the key type associated with the element referenced by an associative iterator `I`.
[heading Header]
#include <boost/fusion/iterator/key_of.hpp>
#include <boost/fusion/include/key_of.hpp>
[heading Example]
typedef __map__<__pair__<float,int> > vec;
typedef __result_of_begin__<vec>::type first;
BOOST_MPL_ASSERT((boost::is_same<__result_of_key_of__<first>::type, float>));
[endsect]
[section value_of_data]
[heading Description]
Returns the type of the data property associated with the element referenced by an associative iterator references.
[heading Synopsis]
template<
typename I
>
struct value_of_data
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __associative_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_value_of_data__<I>::type
[*Return type]: Any type
[*Semantics]: Returns the type of the data property associated with the element referenced by an associative iterator `I`.
[heading Header]
#include <boost/fusion/iterator/value_of_data.hpp>
#include <boost/fusion/include/value_of_data.hpp>
[heading Example]
typedef __map__<__pair__<float,int> > vec;
typedef __result_of_begin__<vec>::type first;
BOOST_MPL_ASSERT((boost::is_same<__result_of_value_of_data__<first>::type, int>));
[endsect]
[section deref_data]
[heading Description]
Returns the type that will be returned by dereferencing the data property referenced by an associative iterator.
[heading Synposis]
template<
typename I
>
struct deref_data
{
typedef __unspecified__ type;
};
[table Parameters
[[Parameter] [Requirement] [Description]]
[[`I`] [Model of __associative_iterator__] [Operation's argument]]
]
[heading Expression Semantics]
__result_of_deref_data__<I>::type
[*Return type]: Any type
[*Semantics]: Returns the result of dereferencing the data property referenced by an associative iterator of type `I`.
[heading Header]
#include <boosta/fusion/iterator/deref_data.hpp>
#include <boost/fusion/include/deref_data.hpp>
[heading Example]
typedef __map__<__pair__<float,int> > map;
typedef __result_of_begin__<vec>::type first;
BOOST_MPL_ASSERT((boost::is_same<__result_of_deref_data__<first>::type, int&>));
[endsect]
[endsect]
[endsect]