algorithm.qbk

Boost provides free peer-reviewed portable C++ source libraries. We emphasize libraries that work

    [[`f`][A unary function object][The search predicate]]
]

[heading Expression Semantics]
    __none__(seq, f);

[*Return type]: `bool`

[*Semantics]: Returns true if and only if `f(e)` evaluates to `false` for every element `e` in `seq`. Result equivalent to `!any(seq, f)`.

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/none.hpp>
    #include <boost/fusion/include/none.hpp>

[heading Example]
    struct odd
    {
        template<typename T>
        bool operator()(T t) const
        {
            return t % 2;
        }
    };
    ...
    assert(__none__(__make_vector__(2,4), odd()));
    assert(!__none__(__make_vector__(1,2), odd()));

[endsect]

[section find]

[heading Description]
Finds the first element of a given type within a sequence.

[heading Synopsis]
    template<
        typename T,
        typename Sequence
        >
    __unspecified__ find(Sequence const& seq);

    template<
        typename T,
        typename Sequence
        >
    __unspecified__ find(Sequence& seq);

[table Parameters
    [[Parameter][Requirement][Description]]
    [[`seq`][A model of __forward_sequence__][The sequence to search]]
    [[`T`][Any type][The type to search for]]
]

[heading Expression Semantics]
    __find__<T>(seq)

[*Return type]: A model of the same iterator category as the iterators of `seq`.

[*Semantics]: Returns an iterator to the first element of `seq` of type `T`, or `__end__(seq)` if there is no such element.
Equivalent to `__find_if__<boost::is_same<_, T> >(seq)`

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/find.hpp>
    #include <boost/fusion/include/find.hpp>

[heading Example]
    const __vector__<char,int> vec('a','0');
    assert(*__find__<int>(vec) == '0');
    assert(__find__<double>(vec) == __end__(vec));

[endsect]

[section find_if]
Finds the first element within a sequence with a type for which a given __mpl_lambda_expression__ evaluates to
`boost::mpl::true_`.

[heading Description]

[heading Synopsis]
    template<
        typename F,
        typename Sequence
        >
    __unspecified__ find_if(Sequence const& seq);

    template<
        typename F,
        typename Sequence
        >
    __unspecified__ find_if(Sequence& seq);

[table Parameters
    [[Parameter][Requirement][Description]]
    [[`seq`][A model of __forward_sequence__][The sequence to search]]
    [[`F`][A unary __mpl_lambda_expression__][The search predicate]]
]

[heading Expression Semantics]
    __find_if__<F>(seq)

[*Return type]: An iterator of the same iterator category as the iterators of `seq`.

[*Semantics]: Returns the first element of `seq` for which __mpl_lambda_expression__ `F` evaluates to `boost::mpl::true_`,
or `__end__(seq)` if there is no such element.

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.


/algorithm/query/find_if.hpp>

[heading Example]
    const __vector__<double,int> vec(1.0,2);
    assert(*__find_if__<is_integral<mpl::_> >(vec) == 2);
    assert(__find_if__<is_class<mpl::_> >(vec) == __end__(vec));

[endsect]

[section count]

[heading Description]
Returns the number of elements of a given type within a sequence.

[heading Synopsis]
    template<
        typename Sequence,
        typename T
        >
    typename __result_of_count__<Sequence, T>::type count(
        Sequence const& seq, T const& t);

[table Parameters
    [[Parameter][Requirement][Description]]
    [[`seq`][A model of __forward_sequence__, `e == t` must be a valid expression, convertible to `bool`, for each element `e` in `seq`][The sequence to search]]
    [[`T`][Any type][The type to count]]
]

[heading Expression Semantics]
    __count__(seq, t);

[*Return type]: `int`

[*Semantics]: Returns the number of elements of type `T` and equal to `t` in `seq`.

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/count.hpp>
    #include <boost/fusion/include/count.hpp>

[heading Example]
    const __vector__<double,int,int> vec(1.0,2,3);
    assert(__count__(vec,2) == 1);

[endsect]

[section count_if]

[heading Description]
Returns the number of elements within a sequence with a type for which a given unary function object evaluates to
`true`.

[heading Synopsis]
    template<
        typename Sequence,
        typename F
        >
    typename __result_of_count_if__<Sequence, F>::type count_if(
        Sequence const& seq, F f);

[table Parameters
    [[Parameter][Requirement][Description]]
    [[`seq`][A model of __forward_sequence__, `f(e)` is a valid expression, convertible to `bool`, for each element `e` in `seq`][The sequence to search]]
    [[`f`][A unary function object][The search predicate]]
]

[heading Expression Semantics]
    __count_if__(seq, f)

[*Return type]: `int`

[*Semantics]: Returns the number of elements in `seq` where `f` evaluates to `true`.

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/count_if.hpp>
    #include <boost/fusion/include/count_if.hpp>

[heading Example]
    const __vector__<int,int,int> vec(1,2,3);
    assert(__count_if__(vec,odd()) == 2);

[endsect]

[endsect]

[section Metafunctions]

[section any]

[heading Description]
A metafunction returning the result type of __any__.

[heading Synopsis]
    template<
        typename Sequence,
        typename F
        >
    struct any
    {
        typedef bool type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`F`]       [A model of unary __poly_func_obj__] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_any__<Sequence, F>::type

[*Return type]: `bool`.

[*Semantics]: Returns the return type of __any__ given a sequence of type `Sequence` and a unary __poly_func_obj__ of type `F`. The return type is always `bool`.

[heading Complexity]
Constant.

[heading Header]

    #include <boost/fusion/algorithm/query/any.hpp>
    #include <boost/fusion/include/any.hpp>

[endsect]

[section all]

[heading Description]
A metafunction returning the result type of __all__.

[heading Synopsis]
    template<
        typename Sequence,
        typename F
        >
    struct all
    {
        typedef bool type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`F`]        [A model of unary __poly_func_obj__] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_all__<Sequence, F>::type

[*Return type]: `bool`.

[*Semantics]: Returns the return type of __all__ given a sequence of type `Sequence` and a unary __poly_func_obj__ of type `F`. The return type is always `bool`.

[heading Complexity]
Constant.

[heading Header]

    #include <boost/fusion/algorithm/query/all.hpp>
    #include <boost/fusion/include/all.hpp>

[endsect]

[section none]

[heading Description]
A metafunction returning the result type of __none__.

[heading Synopsis]
    template<
        typename Sequence,
        typename F
        >
    struct none
    {
        typedef bool type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`F`]        [A model of unary __poly_func_obj__] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_none__<Sequence, F>::type

[*Return type]: `bool`.

[*Semantics]: Returns the return type of __none__ given a sequence of type `Sequence` and a unary __poly_func_obj__ of type `F`. The return type is always `bool`.

[heading Complexity]
Constant.

[heading Header]

    #include <boost/fusion/algorithm/query/none.hpp>
    #include <boost/fusion/include/none.hpp>

[endsect]

[section find]

[heading Description]
Returns the result type of `find`, given the sequence and search types.

[heading Synopsis]
    template<
        typename Sequence,
        typename T
        >
    struct find
    {
        typedef __unspecified__ type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [Model of __forward_sequence__] [Operation's argument]]
    [[`T`]        [Any type] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_find__<Sequence, T>::type

[*Return type]: A model of the same iterator category as the iterators of `Sequence`.

[*Semantics]: Returns an iterator to the first element of type `T` in `Sequence`, or `__result_of_end__<Sequence>::type` if there is no such element.

[heading Complexity]
Linear, at most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/find.hpp>
    #include <boost/fusion/include/find.hpp>

[endsect]

[section find_if]

[heading Description]
Returns the result type of `find_if` given the sequence and predicate types.

[heading Synopsis]
    template<
        typename Sequence,
        typename Pred
        >
    struct find_if
    {
        typedef __unspecified__ type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`Pred`]     [A model of __mpl_lambda_expression__] [Operation's arguments]]
]

[heading Expression Semantics]
    __result_of_find_if__<Sequence, Pred>::type

[*Return type]: A model of the same iterator category as the iterators of `Sequence`.

[*Semantics]: Returns an iterator to the first element in `Sequence` for which `Pred` evaluates to true. Returns `__result_of_end__<Sequence>::type` if there is no such element.

[heading Complexity]
Linear. At most `__result_of_size__<Sequence>::value` comparisons.

[heading Header]

    #include <boost/fusion/algorithm/query/find_if.hpp>
    #include <boost/fusion/include/find_if.hpp>

[endsect]

[section count]

[heading Description]
A metafunction that returns the result type of `count` given the sequence and search types.

[heading Synopsis]
    template<
        typename Sequence,
        typename T
        >
    struct count
    {
        typedef int type;
    };

[table Parameters
    [[Parameter] [Requirement] [heading Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`T`] [Any type] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_count__<T>::type

[*Return type]: `int`.

[*Semantics]: Returns the return type of __count__. The return type is always `int`.

[heading Complexity]
Constant.

[heading Header]

    #include <boost/fusion/algorithm/query/count.hpp>
    #include <boost/fusion/include/count.hpp>

[endsect]

[section count_if]

[heading Description]
A metafunction that returns the result type of `count_if` given the sequence and predicate types.

[heading Synopsis]
    template<
        typename Sequence,
        typename Pred
        >
    struct count_if
    {
        typedef int type;
    };

[table Parameters
    [[Parameter] [Requirement] [Description]]
    [[`Sequence`] [A model of __forward_sequence__] [Operation's argument]]
    [[`Pred`]     [A unary function object] [Operation's argument]]
]

[heading Expression Semantics]
    __result_of_count_if__<Sequence, Pred>::type

[*Return type]: `int`.

[*Semantics]: Returns the return type of __count_if__. The return type is always `int`.

[heading Complexity]
Constant.