113 lines
4.2 KiB
C
113 lines
4.2 KiB
C
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// 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 <utility>
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#include "build/build_config.h"
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namespace base {
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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 Tuple, size_t... Ns>
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inline void DispatchToMethodImpl(const ObjT& obj,
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Method method,
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Tuple&& args,
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std::index_sequence<Ns...>) {
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(obj->*method)(std::get<Ns>(std::forward<Tuple>(args))...);
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}
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template <typename ObjT, typename Method, typename Tuple>
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inline void DispatchToMethod(const ObjT& obj,
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Method method,
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Tuple&& args) {
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constexpr size_t size = std::tuple_size<std::decay_t<Tuple>>::value;
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DispatchToMethodImpl(obj, method, std::forward<Tuple>(args),
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std::make_index_sequence<size>());
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}
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// Static Dispatchers with no out params.
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template <typename Function, typename Tuple, size_t... Ns>
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inline void DispatchToFunctionImpl(Function function,
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Tuple&& args,
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std::index_sequence<Ns...>) {
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(*function)(std::get<Ns>(std::forward<Tuple>(args))...);
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}
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template <typename Function, typename Tuple>
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inline void DispatchToFunction(Function function, Tuple&& args) {
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constexpr size_t size = std::tuple_size<std::decay_t<Tuple>>::value;
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DispatchToFunctionImpl(function, std::forward<Tuple>(args),
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std::make_index_sequence<size>());
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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 InTuple,
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typename OutTuple,
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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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InTuple&& in,
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OutTuple* out,
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std::index_sequence<InNs...>,
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std::index_sequence<OutNs...>) {
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(obj->*method)(std::get<InNs>(std::forward<InTuple>(in))...,
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&std::get<OutNs>(*out)...);
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}
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template <typename ObjT, typename Method, typename InTuple, typename OutTuple>
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inline void DispatchToMethod(const ObjT& obj,
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Method method,
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InTuple&& in,
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OutTuple* out) {
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constexpr size_t in_size = std::tuple_size<std::decay_t<InTuple>>::value;
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constexpr size_t out_size = std::tuple_size<OutTuple>::value;
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DispatchToMethodImpl(obj, method, std::forward<InTuple>(in), out,
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std::make_index_sequence<in_size>(),
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std::make_index_sequence<out_size>());
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}
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} // namespace base
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#endif // BASE_TUPLE_H_
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