195 lines
6.5 KiB
C++
195 lines
6.5 KiB
C++
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Use std::tuple as tuple type. This file contains helper functions for
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// working with std::tuples.
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// The functions DispatchToMethod and DispatchToFunction take a function pointer
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// or instance and method pointer, and unpack a tuple into arguments to the
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// call.
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//
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// Example usage:
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// // These two methods of creating a Tuple are identical.
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// std::tuple<int, const char*> tuple_a(1, "wee");
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// std::tuple<int, const char*> tuple_b = std::make_tuple(1, "wee");
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//
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// void SomeFunc(int a, const char* b) { }
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// DispatchToFunction(&SomeFunc, tuple_a); // SomeFunc(1, "wee")
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// DispatchToFunction(
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// &SomeFunc, std::make_tuple(10, "foo")); // SomeFunc(10, "foo")
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//
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// struct { void SomeMeth(int a, int b, int c) { } } foo;
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// DispatchToMethod(&foo, &Foo::SomeMeth, std::make_tuple(1, 2, 3));
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// // foo->SomeMeth(1, 2, 3);
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#ifndef BASE_TUPLE_H_
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#define BASE_TUPLE_H_
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#include <stddef.h>
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#include <tuple>
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#include "base/bind_helpers.h"
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#include "build/build_config.h"
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namespace base {
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// Index sequences
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//
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// Minimal clone of the similarly-named C++14 functionality.
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template <size_t...>
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struct IndexSequence {};
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template <size_t... Ns>
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struct MakeIndexSequenceImpl;
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#if defined(_PREFAST_) && defined(OS_WIN)
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// Work around VC++ 2013 /analyze internal compiler error:
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// https://connect.microsoft.com/VisualStudio/feedback/details/1053626
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template <> struct MakeIndexSequenceImpl<0> {
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using Type = IndexSequence<>;
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};
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template <> struct MakeIndexSequenceImpl<1> {
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using Type = IndexSequence<0>;
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};
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template <> struct MakeIndexSequenceImpl<2> {
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using Type = IndexSequence<0,1>;
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};
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template <> struct MakeIndexSequenceImpl<3> {
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using Type = IndexSequence<0,1,2>;
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};
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template <> struct MakeIndexSequenceImpl<4> {
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using Type = IndexSequence<0,1,2,3>;
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};
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template <> struct MakeIndexSequenceImpl<5> {
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using Type = IndexSequence<0,1,2,3,4>;
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};
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template <> struct MakeIndexSequenceImpl<6> {
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using Type = IndexSequence<0,1,2,3,4,5>;
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};
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template <> struct MakeIndexSequenceImpl<7> {
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using Type = IndexSequence<0,1,2,3,4,5,6>;
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};
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template <> struct MakeIndexSequenceImpl<8> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7>;
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};
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template <> struct MakeIndexSequenceImpl<9> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7,8>;
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};
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template <> struct MakeIndexSequenceImpl<10> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9>;
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};
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template <> struct MakeIndexSequenceImpl<11> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10>;
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};
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template <> struct MakeIndexSequenceImpl<12> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10,11>;
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};
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template <> struct MakeIndexSequenceImpl<13> {
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using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10,11,12>;
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};
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#else // defined(OS_WIN) && defined(_PREFAST_)
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template <size_t... Ns>
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struct MakeIndexSequenceImpl<0, Ns...> {
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using Type = IndexSequence<Ns...>;
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};
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template <size_t N, size_t... Ns>
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struct MakeIndexSequenceImpl<N, Ns...>
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: MakeIndexSequenceImpl<N - 1, N - 1, Ns...> {};
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#endif // defined(OS_WIN) && defined(_PREFAST_)
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// std::get() in <=libstdc++-4.6 returns an lvalue-reference for
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// rvalue-reference of a tuple, where an rvalue-reference is expected.
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template <size_t I, typename... Ts>
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typename std::tuple_element<I, std::tuple<Ts...>>::type&& get(
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std::tuple<Ts...>&& t) {
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using ElemType = typename std::tuple_element<I, std::tuple<Ts...>>::type;
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return std::forward<ElemType>(std::get<I>(t));
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}
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template <size_t I, typename T>
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auto get(T& t) -> decltype(std::get<I>(t)) {
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return std::get<I>(t);
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}
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template <size_t N>
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using MakeIndexSequence = typename MakeIndexSequenceImpl<N>::Type;
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// Dispatchers ----------------------------------------------------------------
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//
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// Helper functions that call the given method on an object, with the unpacked
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// tuple arguments. Notice that they all have the same number of arguments,
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// so you need only write:
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// DispatchToMethod(object, &Object::method, args);
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// This is very useful for templated dispatchers, since they don't need to know
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// what type |args| is.
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// Non-Static Dispatchers with no out params.
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template <typename ObjT, typename Method, typename... Ts, size_t... Ns>
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inline void DispatchToMethodImpl(const ObjT& obj,
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Method method,
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const std::tuple<Ts...>& arg,
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IndexSequence<Ns...>) {
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(obj->*method)(internal::Unwrap(std::get<Ns>(arg))...);
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}
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template <typename ObjT, typename Method, typename... Ts>
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inline void DispatchToMethod(const ObjT& obj,
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Method method,
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const std::tuple<Ts...>& arg) {
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DispatchToMethodImpl(obj, method, arg, MakeIndexSequence<sizeof...(Ts)>());
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}
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// Static Dispatchers with no out params.
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template <typename Function, typename... Ts, size_t... Ns>
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inline void DispatchToFunctionImpl(Function function,
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const std::tuple<Ts...>& arg,
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IndexSequence<Ns...>) {
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(*function)(internal::Unwrap(std::get<Ns>(arg))...);
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}
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template <typename Function, typename... Ts>
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inline void DispatchToFunction(Function function,
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const std::tuple<Ts...>& arg) {
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DispatchToFunctionImpl(function, arg, MakeIndexSequence<sizeof...(Ts)>());
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}
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// Dispatchers with out parameters.
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template <typename ObjT,
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typename Method,
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typename... InTs,
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typename... OutTs,
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size_t... InNs,
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size_t... OutNs>
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inline void DispatchToMethodImpl(const ObjT& obj,
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Method method,
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const std::tuple<InTs...>& in,
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std::tuple<OutTs...>* out,
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IndexSequence<InNs...>,
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IndexSequence<OutNs...>) {
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(obj->*method)(internal::Unwrap(std::get<InNs>(in))...,
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&std::get<OutNs>(*out)...);
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}
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template <typename ObjT, typename Method, typename... InTs, typename... OutTs>
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inline void DispatchToMethod(const ObjT& obj,
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Method method,
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const std::tuple<InTs...>& in,
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std::tuple<OutTs...>* out) {
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DispatchToMethodImpl(obj, method, in, out,
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MakeIndexSequence<sizeof...(InTs)>(),
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MakeIndexSequence<sizeof...(OutTs)>());
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}
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} // namespace base
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#endif // BASE_TUPLE_H_
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