зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1482046 - mfbt: FunctionTypeTraits - r=froydnj
FunctionTypeTraits< function type > makes it easier to inspect a function's return type, arity, and parameter types. It works with free functions, struct/class methods, function objects like non-generic lambdas and std::function. Differential Revision: https://phabricator.services.mozilla.com/D2998 --HG-- extra : moz-landing-system : lando
This commit is contained in:
Gerald Squelart
Родитель
9382a39249
Коммит
2d21b03a3b
|
|
@ -0,0 +1,136 @@
|
|||
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
||||
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
||||
/* This Source Code Form is subject to the terms of the Mozilla Public
|
||||
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
||||
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
||||
|
||||
/* Helpers to manipulate function types that don't fit in TypeTraits.h */
|
||||
|
||||
#ifndef mozilla_FunctionTypeTraits_h
|
||||
#define mozilla_FunctionTypeTraits_h
|
||||
|
||||
#include <tuple>
|
||||
|
||||
namespace mozilla {
|
||||
|
||||
// Main FunctionTypeTraits declaration, taking one template argument.
|
||||
//
|
||||
// Given a function type, FunctionTypeTraits will expose the following members:
|
||||
// - ReturnType: Return type.
|
||||
// - arity: Number of parameters (size_t).
|
||||
// - ParameterType<N>: Type of the Nth** parameter, 0-indexed.
|
||||
//
|
||||
// ** `ParameterType<N>` with `N` >= `arity` is allowed and gives `void`.
|
||||
// This prevents compilation errors when trying to access a type outside of the
|
||||
// function's parameters, which is useful for parameters checks, e.g.:
|
||||
// template<typename F>
|
||||
// auto foo(F&&)
|
||||
// -> enable_if(FunctionTypeTraits<F>::arity == 1 &&
|
||||
// is_same<FunctionTypeTraits<F>::template ParameterType<0>,
|
||||
// int>::value,
|
||||
// void)
|
||||
// {
|
||||
// // This function will only be enabled if `F` takes one `int`.
|
||||
// // Without the permissive ParameterType<any N>, it wouldn't even compile.
|
||||
//
|
||||
// Note: FunctionTypeTraits does not work with generic lambdas `[](auto&) {}`,
|
||||
// because parameter types cannot be known until an actual invocation when types
|
||||
// are inferred from the given arguments.
|
||||
template<typename T>
|
||||
struct FunctionTypeTraits;
|
||||
|
||||
// Remove reference and pointer wrappers, if any.
|
||||
template<typename T>
|
||||
struct FunctionTypeTraits<T&> : public FunctionTypeTraits<T>
|
||||
{
|
||||
};
|
||||
template<typename T>
|
||||
struct FunctionTypeTraits<T&&> : public FunctionTypeTraits<T>
|
||||
{
|
||||
};
|
||||
template<typename T>
|
||||
struct FunctionTypeTraits<T*> : public FunctionTypeTraits<T>
|
||||
{
|
||||
};
|
||||
|
||||
// Extract `operator()` function from callables (e.g. lambdas, std::function).
|
||||
template<typename T>
|
||||
struct FunctionTypeTraits : public FunctionTypeTraits<decltype(&T::operator())>
|
||||
{
|
||||
};
|
||||
|
||||
namespace detail {
|
||||
|
||||
// If `safe`, retrieve the `N`th type from `As`, otherwise `void`.
|
||||
// See top description for reason.
|
||||
template<bool safe, size_t N, typename... As>
|
||||
struct TupleElementSafe;
|
||||
template<size_t N, typename... As>
|
||||
struct TupleElementSafe<true, N, As...>
|
||||
{
|
||||
using Type = typename std::tuple_element<N, std::tuple<As...>>::type;
|
||||
};
|
||||
template<size_t N, typename... As>
|
||||
struct TupleElementSafe<false, N, As...>
|
||||
{
|
||||
using Type = void;
|
||||
};
|
||||
|
||||
template<typename R, typename... As>
|
||||
struct FunctionTypeTraitsHelper
|
||||
{
|
||||
using ReturnType = R;
|
||||
static constexpr size_t arity = sizeof...(As);
|
||||
template<size_t N>
|
||||
using ParameterType =
|
||||
typename TupleElementSafe<(N < sizeof...(As)), N, As...>::Type;
|
||||
};
|
||||
|
||||
} // namespace detail
|
||||
|
||||
// Specialization for free functions.
|
||||
template<typename R, typename... As>
|
||||
struct FunctionTypeTraits<R(As...)> : detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
|
||||
// Specialization for non-const member functions.
|
||||
template<typename C, typename R, typename... As>
|
||||
struct FunctionTypeTraits<R (C::*)(As...)>
|
||||
: detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
|
||||
// Specialization for const member functions.
|
||||
template<typename C, typename R, typename... As>
|
||||
struct FunctionTypeTraits<R (C::*)(As...) const>
|
||||
: detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
|
||||
#ifdef NS_HAVE_STDCALL
|
||||
// Specialization for __stdcall free functions.
|
||||
template<typename R, typename... As>
|
||||
struct FunctionTypeTraits<R NS_STDCALL(As...)>
|
||||
: detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
|
||||
// Specialization for __stdcall non-const member functions.
|
||||
template<typename C, typename R, typename... As>
|
||||
struct FunctionTypeTraits<R (NS_STDCALL C::*)(As...)>
|
||||
: detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
|
||||
// Specialization for __stdcall const member functions.
|
||||
template<typename C, typename R, typename... As>
|
||||
struct FunctionTypeTraits<R (NS_STDCALL C::*)(As...) const>
|
||||
: detail::FunctionTypeTraitsHelper<R, As...>
|
||||
{
|
||||
};
|
||||
#endif // NS_HAVE_STDCALL
|
||||
|
||||
} // namespace mozilla
|
||||
|
||||
#endif // mozilla_FunctionTypeTraits_h
|
||||
|
|
@ -42,6 +42,7 @@ EXPORTS.mozilla = [
|
|||
'FastBernoulliTrial.h',
|
||||
'FloatingPoint.h',
|
||||
'FStream.h',
|
||||
'FunctionTypeTraits.h',
|
||||
'GuardObjects.h',
|
||||
'HashFunctions.h',
|
||||
'HashTable.h',
|
||||
|
|
|
|||
|
|
@ -0,0 +1,261 @@
|
|||
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
||||
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
||||
/* This Source Code Form is subject to the terms of the Mozilla Public
|
||||
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
|
||||
* You can obtain one at http://mozilla.org/MPL/2.0/. */
|
||||
|
||||
#include "mozilla/FunctionTypeTraits.h"
|
||||
|
||||
#include <functional>
|
||||
|
||||
using mozilla::FunctionTypeTraits;
|
||||
|
||||
void
|
||||
f0()
|
||||
{
|
||||
}
|
||||
|
||||
int
|
||||
f1(char)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
|
||||
#ifdef NS_HAVE_STDCALL
|
||||
void NS_STDCALL
|
||||
f0s()
|
||||
{
|
||||
}
|
||||
|
||||
int NS_STDCALL
|
||||
f1s(char)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
#endif // NS_HAVE_STDCALL
|
||||
|
||||
struct S
|
||||
{
|
||||
void f0() {}
|
||||
void f0c() const {}
|
||||
int f1(char) { return 0; }
|
||||
int f1c(char) const { return 0; }
|
||||
#ifdef NS_HAVE_STDCALL
|
||||
void NS_STDCALL f0s() {}
|
||||
void NS_STDCALL f0cs() const {}
|
||||
int NS_STDCALL f1s(char) { return 0; }
|
||||
int NS_STDCALL f1cs(char) const { return 0; }
|
||||
#endif // NS_HAVE_STDCALL
|
||||
};
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(f0)>::ReturnType,
|
||||
void>::value,
|
||||
"f0 returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(f0)>::arity == 0,
|
||||
"f0 takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(f0)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"f0 has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f0)>::ReturnType,
|
||||
void>::value,
|
||||
"S::f0 returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f0)>::arity == 0,
|
||||
"S::f0 takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f0)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"S::f0 has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f0c)>::ReturnType,
|
||||
void>::value,
|
||||
"S::f0c returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f0c)>::arity == 0,
|
||||
"S::f0c takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f0c)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"S::f0c has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(f1)>::ReturnType,
|
||||
int>::value,
|
||||
"f1 returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(f1)>::arity == 1,
|
||||
"f1 takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(f1)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"f1 takes a char");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f1)>::ReturnType,
|
||||
int>::value,
|
||||
"S::f1 returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f1)>::arity == 1,
|
||||
"S::f1 takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f1)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"S::f1 takes a char");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f1c)>::ReturnType,
|
||||
int>::value,
|
||||
"S::f1c returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f1c)>::arity == 1,
|
||||
"S::f1c takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f1c)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"S::f1c takes a char");
|
||||
|
||||
#ifdef NS_HAVE_STDCALL
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(f0s)>::ReturnType,
|
||||
void>::value,
|
||||
"f0s returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(f0s)>::arity == 0,
|
||||
"f0s takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(f0s)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"f0s has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f0s)>::ReturnType,
|
||||
void>::value,
|
||||
"S::f0s returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f0s)>::arity == 0,
|
||||
"S::f0s takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f0s)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"S::f0s has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f0cs)>::ReturnType,
|
||||
void>::value,
|
||||
"S::f0cs returns void");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f0cs)>::arity == 0,
|
||||
"S::f0cs takes no parameters");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f0cs)>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"S::f0cs has no first parameter");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(f1s)>::ReturnType,
|
||||
int>::value,
|
||||
"f1s returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(f1s)>::arity == 1,
|
||||
"f1s takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(f1s)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"f1s takes a char");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f1s)>::ReturnType,
|
||||
int>::value,
|
||||
"S::f1s returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f1s)>::arity == 1,
|
||||
"S::f1s takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f1s)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"S::f1s takes a char");
|
||||
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<decltype(&S::f1cs)>::ReturnType,
|
||||
int>::value,
|
||||
"S::f1cs returns int");
|
||||
static_assert(FunctionTypeTraits<decltype(&S::f1cs)>::arity == 1,
|
||||
"S::f1cs takes one parameter");
|
||||
static_assert(
|
||||
std::is_same<
|
||||
typename FunctionTypeTraits<decltype(&S::f1cs)>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"S::f1cs takes a char");
|
||||
#endif // NS_HAVE_STDCALL
|
||||
|
||||
template<typename F>
|
||||
void
|
||||
TestVoidVoid(F&&)
|
||||
{
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<F>::ReturnType, void>::value,
|
||||
"Should return void");
|
||||
static_assert(FunctionTypeTraits<F>::arity == 0, "Should take no parameters");
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<F>::template ParameterType<0>,
|
||||
void>::value,
|
||||
"Should have no first parameter");
|
||||
}
|
||||
|
||||
template<typename F>
|
||||
void
|
||||
TestIntChar(F&&)
|
||||
{
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<F>::ReturnType, int>::value,
|
||||
"Should return int");
|
||||
static_assert(FunctionTypeTraits<F>::arity == 1, "Should take one parameter");
|
||||
static_assert(
|
||||
std::is_same<typename FunctionTypeTraits<F>::template ParameterType<0>,
|
||||
char>::value,
|
||||
"Should take a char");
|
||||
}
|
||||
|
||||
int
|
||||
main()
|
||||
{
|
||||
TestVoidVoid(f0);
|
||||
TestVoidVoid(&f0);
|
||||
TestVoidVoid(&S::f0);
|
||||
TestVoidVoid(&S::f0c);
|
||||
TestVoidVoid([]() {});
|
||||
std::function<void()> ff0 = f0;
|
||||
TestVoidVoid(ff0);
|
||||
|
||||
TestIntChar(f1);
|
||||
TestIntChar(&f1);
|
||||
TestIntChar(&S::f1);
|
||||
TestIntChar(&S::f1c);
|
||||
TestIntChar([](char) { return 0; });
|
||||
std::function<int(char)> ff1 = f1;
|
||||
TestIntChar(ff1);
|
||||
|
||||
#ifdef NS_HAVE_STDCALL
|
||||
TestVoidVoid(f0s);
|
||||
TestVoidVoid(&f0s);
|
||||
TestVoidVoid(&S::f0s);
|
||||
TestVoidVoid(&S::f0cs);
|
||||
std::function<void()> ff0s = f0s;
|
||||
TestVoidVoid(ff0s);
|
||||
|
||||
TestIntChar(f1s);
|
||||
TestIntChar(&f1s);
|
||||
TestIntChar(&S::f1s);
|
||||
TestIntChar(&S::f1cs);
|
||||
std::function<int(char)> ff1s = f1s;
|
||||
TestIntChar(ff1s);
|
||||
#endif // NS_HAVE_STDCALL
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -30,6 +30,7 @@ CppUnitTests([
|
|||
'TestEnumTypeTraits',
|
||||
'TestFastBernoulliTrial',
|
||||
'TestFloatingPoint',
|
||||
'TestFunctionTypeTraits',
|
||||
'TestIntegerPrintfMacros',
|
||||
'TestIntegerRange',
|
||||
'TestJSONWriter',
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче