[functional.syn] (original) (raw)

20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.2 Header synopsis [functional.syn]

namespace std { // [func.invoke], invoke template<class F, class... Args> constexpr invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) noexcept(is_nothrow_invocable_v<F, Args...>);// [refwrap], reference_­wrapper template<class T> class reference_wrapper;template<class T> constexpr reference_wrapper<T> ref(T&) noexcept;template<class T> constexpr reference_wrapper<const T> cref(const T&) noexcept;template<class T> void ref(const T&&) = delete;template<class T> void cref(const T&&) = delete;template<class T> constexpr reference_wrapper<T> ref(reference_wrapper<T>) noexcept;template<class T> constexpr reference_wrapper<const T> cref(reference_wrapper<T>) noexcept;// [arithmetic.operations], arithmetic operations template<class T = void> struct plus;template<class T = void> struct minus;template<class T = void> struct multiplies;template<class T = void> struct divides;template<class T = void> struct modulus;template<class T = void> struct negate;template<> struct plus<void>;template<> struct minus<void>;template<> struct multiplies<void>;template<> struct divides<void>;template<> struct modulus<void>;template<> struct negate<void>;// [comparisons], comparisons template<class T = void> struct equal_to;template<class T = void> struct not_equal_to;template<class T = void> struct greater;template<class T = void> struct less;template<class T = void> struct greater_equal;template<class T = void> struct less_equal;template<> struct equal_to<void>;template<> struct not_equal_to<void>;template<> struct greater<void>;template<> struct less<void>;template<> struct greater_equal<void>;template<> struct less_equal<void>;// [comparisons.three.way], class compare_­three_­way struct compare_three_way;// [logical.operations], logical operations template<class T = void> struct logical_and;template<class T = void> struct logical_or;template<class T = void> struct logical_not;template<> struct logical_and<void>;template<> struct logical_or<void>;template<> struct logical_not<void>;// [bitwise.operations], bitwise operations template<class T = void> struct bit_and;template<class T = void> struct bit_or;template<class T = void> struct bit_xor;template<class T = void> struct bit_not;template<> struct bit_and<void>;template<> struct bit_or<void>;template<> struct bit_xor<void>;template<> struct bit_not<void>;// [func.identity], identity struct identity;// [func.not.fn], function template not_­fn template<class F> constexpr unspecified not_fn(F&& f);// [func.bind.front], function template bind_­front template<class F, class... Args> constexpr unspecified bind_front(F&&, Args&&...);// [func.bind], bind template<class T> struct is_bind_expression;template<class T> inline constexpr bool is_bind_expression_v = is_bind_expression<T>::value;template<class T> struct is_placeholder;template<class T> inline constexpr int is_placeholder_v = is_placeholder<T>::value;template<class F, class... BoundArgs> constexpr unspecified bind(F&&, BoundArgs&&...);template<class R, class F, class... BoundArgs> constexpr unspecified bind(F&&, BoundArgs&&...);namespace placeholders { // M is the implementation-defined number of placeholders see below _1;see below _2;. . . see below _ M;} // [func.memfn], member function adaptors template<class R, class T> constexpr unspecified mem_fn(R T::*) noexcept;// [func.wrap], polymorphic function wrappers class bad_function_call;template<class> class function; // not defined template<class R, class... ArgTypes> class function<R(ArgTypes...)>;template<class R, class... ArgTypes> void swap(function<R(ArgTypes...)>&, function<R(ArgTypes...)>&) noexcept;template<class R, class... ArgTypes> bool operator==(const function<R(ArgTypes...)>&, nullptr_t) noexcept;// [func.search], searchers template<class ForwardIterator, class BinaryPredicate = equal_to<>> class default_searcher;template<class RandomAccessIterator,class Hash = hash<typename iterator_traits<RandomAccessIterator>::value_type>,class BinaryPredicate = equal_to<>> class boyer_moore_searcher;template<class RandomAccessIterator,class Hash = hash<typename iterator_traits<RandomAccessIterator>::value_type>,class BinaryPredicate = equal_to<>> class boyer_moore_horspool_searcher;// [unord.hash], class template hash template<class T> struct hash;namespace ranges { // [range.cmp], concept-constrained comparisons struct equal_to;struct not_equal_to;struct greater;struct less;struct greater_equal;struct less_equal;} }

[Example 1:

If a C++ program wants to have a by-element addition of two vectors aand b containing double and put the result into a, it can do:transform(a.begin(), a.end(), b.begin(), a.begin(), plus<double>());

— _end example_]

[Example 2:

To negate every element of a:transform(a.begin(), a.end(), a.begin(), negate<double>());

— _end example_]