vmap/libs/generic/callback.h
2020-11-17 12:16:16 +01:00

349 lines
10 KiB
C++

/*
Copyright (C) 2001-2006, William Joseph.
All Rights Reserved.
This file is part of GtkRadiant.
GtkRadiant is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
GtkRadiant is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#if !defined( INCLUDED_GENERIC_CLOSURE_H )
#define INCLUDED_GENERIC_CLOSURE_H
/// \file
/// \brief Type-safe techniques for binding the first argument of an opaque callback.
#include <cstddef>
#include "functional.h"
namespace detail {
template<typename Thunk_>
class CallbackBase {
void *m_environment;
Thunk_ m_thunk;
public:
typedef Thunk_ Thunk;
CallbackBase(void *environment, Thunk function) : m_environment(environment), m_thunk(function) {
}
void *getEnvironment() const {
return m_environment;
}
Thunk getThunk() const {
return m_thunk;
}
};
template<typename Thunk>
inline bool operator==(const CallbackBase<Thunk> &self, const CallbackBase<Thunk> &other) {
return self.getEnvironment() == other.getEnvironment() && self.getThunk() == other.getThunk();
}
template<typename Thunk>
inline bool operator!=(const CallbackBase<Thunk> &self, const CallbackBase<Thunk> &other) {
return !(self == other);
}
template<typename Thunk>
inline bool operator<(const CallbackBase<Thunk> &self, const CallbackBase<Thunk> &other) {
return self.getEnvironment() < other.getEnvironment() ||
(!(other.getEnvironment() < self.getEnvironment()) && self.getThunk() < other.getThunk());
}
}
namespace detail {
template<class Type>
struct ConvertFromOpaque {
};
// reference
template<class T>
inline const void *convertToOpaque(const T &t) {
return &t;
}
template<class T>
struct ConvertFromOpaque<const T &> {
static T const &apply(void *p) {
return *static_cast<const T *>(p);
}
};
template<class T>
inline void *convertToOpaque(T &t) {
return &t;
}
template<class T>
struct ConvertFromOpaque<T &> {
static T &apply(void *p) {
return *static_cast<T *>( p );
}
};
// pointer
template<class T>
inline const void *convertToOpaque(const T *t) {
return t;
}
template<class T>
struct ConvertFromOpaque<const T *> {
static const T *apply(void *p) {
return static_cast<const T *>(p);
}
};
template<class T>
inline void *convertToOpaque(T *t) {
return t;
}
template<class T>
struct ConvertFromOpaque<T *> {
static T *apply(void *p) {
return static_cast<T *>(p);
}
};
// function pointer
template<class R, class... Ts>
inline const void *convertToOpaque(R(*const &t)(Ts...)) {
return &t;
}
template<class R, class... Ts>
struct ConvertFromOpaque<R(*const &)(Ts...)> {
using Type = R(*)(Ts...);
static Type const &apply(void *p) {
return *static_cast<Type *>(p);
}
};
template<class R, class... Ts>
inline void *convertToOpaque(R(*&t)(Ts...)) {
return &t;
}
template<class R, class... Ts>
struct ConvertFromOpaque<R(*&)(Ts...)> {
using Type = R(*)(Ts...);
static Type &apply(void *p) {
return *static_cast<Type *>(p);
}
};
template<class Caller, class F>
class BindFirstOpaqueN;
template<class Caller, class R, class FirstBound, class... Ts>
class BindFirstOpaqueN<Caller, R(FirstBound, Ts...)> {
FirstBound firstBound;
public:
explicit BindFirstOpaqueN(FirstBound firstBound) : firstBound(firstBound) {
}
R operator()(Ts... args) const {
return Caller::call(firstBound, args...);
}
FirstBound getBound() const {
return firstBound;
}
static R thunk(void *environment, Ts... args) {
return thunk_(detail::ConvertFromOpaque<FirstBound>::apply(environment), args...);
}
static R thunk_(FirstBound environment, Ts... args) {
return Caller::call(environment, args...);
}
void *getEnvironment() const {
return const_cast<void *>(detail::convertToOpaque(firstBound));
}
};
}
template<class Caller>
using BindFirstOpaque = detail::BindFirstOpaqueN<Caller, get_func<Caller>>;
/// \brief Combines a void pointer with a pointer to a function which operates on a void pointer.
///
/// Use with the callback constructors MemberCaller0, ConstMemberCaller0, ReferenceCaller0, ConstReferenceCaller0, PointerCaller0, ConstPointerCaller0 and FreeCaller0.
template<class F>
class Callback;
template<class R, class... Ts>
class Callback<R(Ts...)> : public detail::CallbackBase<R(*)(void *, Ts...)> {
using Base = detail::CallbackBase<R (*)(void *, Ts...)>;
static R nullThunk(void *, Ts...) {
}
public:
using func = R(Ts...);
Callback() : Base(0, nullThunk) {
}
template<typename Caller>
Callback(const BindFirstOpaque<Caller> &caller) : Base(caller.getEnvironment(), BindFirstOpaque<Caller>::thunk) {
}
Callback(void *environment, typename Base::Thunk function) : Base(environment, function) {
}
R operator()(Ts... args) const {
return Base::getThunk()(Base::getEnvironment(), args...);
}
};
namespace detail {
template<class F>
struct Arglist;
template<class R, class Head, class... Ts>
struct Arglist<R(Head, Ts...)> {
using type = R(Head, Ts...);
template <class Unshift>
using unshift = Arglist<R(Unshift, Head, Ts...)>;
using shift = Arglist<R(Ts...)>;
};
template<class R, class... Ts>
struct Arglist<R(Ts...)> {
using type = R(Ts...);
template <class Unshift>
using unshift = Arglist<R(Unshift, Ts...)>;
};
template<class F>
using ArgShift = typename detail::Arglist<F>::shift::type;
template<class F, class T>
using ArgUnshift = typename detail::Arglist<F>::template unshift<T>::type;
}
template<typename Caller>
inline Callback<detail::ArgShift<get_func<Caller>>> makeCallback(const Caller &caller, get_argument<Caller, 0> callee) {
return BindFirstOpaque<Caller>(callee);
}
template<class Caller, class F>
class CallerShiftFirst;
template<class Caller, class R, class FirstArgument, class... Ts>
class CallerShiftFirst<Caller, R(FirstArgument, Ts...)> {
public:
using func = R(FirstArgument, Ts...);
static R call(FirstArgument, Ts... args) {
return Caller::call(args...);
}
};
template<typename Caller>
inline Callback<get_func<Caller>> makeStatelessCallback(const Caller &caller) {
return makeCallback(CallerShiftFirst<Caller, detail::ArgUnshift<get_func<Caller>, void *>>(), nullptr);
}
/// \brief Forms a Callback from a non-const Environment reference and a non-const Environment member-function.
template<class Environment, class F, MemberFunction<Environment, F> member>
using MemberCaller = BindFirstOpaque<Member<Environment, F, member>>;
/// \brief Constructs a Callback1 from a non-const \p functor
///
/// \param Functor Must define \c first_argument_type and \c operator()(first_argument_type).
template<typename Functor>
inline Callback<get_func<Functor>> makeCallback(Functor &functor) {
return MemberCaller<Functor, get_func<Functor>, &Functor::operator()>(functor);
}
/// \brief Forms a Callback from a const Environment reference and a const Environment member-function.
template<class Environment, class F, ConstMemberFunction<Environment, F> member>
using ConstMemberCaller = BindFirstOpaque<ConstMember<Environment, F, member>>;
/// \brief Constructs a Callback1 from a const \p functor
///
/// \param Functor Must define \c first_argument_type and const \c operator()(first_argument_type).
template<typename Functor>
inline Callback<get_func<Functor>> makeCallback(const Functor &functor) {
return ConstMemberCaller<Functor, get_func<Functor>, &Functor::operator()>(functor);
}
/// \brief Forms a Callback from a non-const Environment reference and a free function which operates on a non-const Environment reference.
template<class Environment, class F, detail::ArgUnshift<F, Environment &> *func>
using ReferenceCaller = BindFirstOpaque<Function<detail::ArgUnshift<F, Environment &>, func>>;
/// \brief Forms a Callback from a const Environment reference and a free function which operates on a const Environment reference.
template<class Environment, class F, detail::ArgUnshift<F, const Environment &> *func>
using ConstReferenceCaller = BindFirstOpaque<Function<detail::ArgUnshift<F, const Environment &>, func>>;
/// \brief Forms a Callback from a non-const Environment pointer and a free function which operates on a non-const Environment pointer.
template<class Environment, class F, detail::ArgUnshift<F, Environment *> *func>
using PointerCaller = BindFirstOpaque<Function<detail::ArgUnshift<F, Environment *>, func>>;
/// \brief Forms a Callback from a const Environment pointer and a free function which operates on a const Environment pointer.
template<class Environment, class F, detail::ArgUnshift<F, const Environment *> *func>
using ConstPointerCaller = BindFirstOpaque<Function<detail::ArgUnshift<F, const Environment *>, func>>;
namespace detail {
template<class Caller, class F>
class FreeCaller : public BindFirstOpaque<CallerShiftFirst<Caller, detail::ArgUnshift<F, void *>>> {
public:
FreeCaller() : BindFirstOpaque<CallerShiftFirst<Caller, detail::ArgUnshift<F, void *>>>(nullptr) {
}
};
template<class F>
struct FreeCallerWrapper;
template<class R, class... Ts>
struct FreeCallerWrapper<R(Ts...)> {
using func = R(void *, Ts...);
static R call(void *f, Ts... args) {
// ideally, we'd get the implementation of the function type directly. Instead, it's passed in
return reinterpret_cast<R(*)(Ts...)>(f)(args...);
}
};
}
/// \brief Forms a Callback from a free function
template<class F, F *func>
using FreeCaller = detail::FreeCaller<Function<F, func>, F>;
template<class R, class... Ts>
inline Callback<R(Ts...)> makeCallbackF(R(*func)(Ts...)) {
void *pVoid = reinterpret_cast<void *>(func);
return BindFirstOpaque<detail::FreeCallerWrapper<R(Ts...)>>(pVoid);
}
#endif