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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkFunction_DEFINED
#define SkFunction_DEFINED
// TODO: document, more pervasive move support in constructors, small-Fn optimization
#include "SkUtility.h"
#include "SkUniquePtr.h"
#include "SkTypes.h"
template <typename> class SkFunction;
template <typename R, typename... Args>
class SkFunction<R(Args...)> {
public:
SkFunction() {}
template <typename Fn>
SkFunction(const Fn& fn)
: fFunction(new LambdaImpl<Fn>(fn)) {}
SkFunction(R (*fn)(Args...)) : fFunction(new FnPtrImpl(fn)) {}
SkFunction(const SkFunction& other) { *this = other; }
SkFunction& operator=(const SkFunction& other) {
if (this != &other) {
fFunction.reset(other.fFunction.get() ? other.fFunction->clone() : nullptr);
}
return *this;
}
R operator()(Args... args) const {
SkASSERT(fFunction.get());
return fFunction->call(skstd::forward<Args>(args)...);
}
private:
struct Interface {
virtual ~Interface() {}
virtual R call(Args...) const = 0;
virtual Interface* clone() const = 0;
};
template <typename Fn>
class LambdaImpl final : public Interface {
public:
LambdaImpl(const Fn& fn) : fFn(fn) {}
R call(Args... args) const override { return fFn(skstd::forward<Args>(args)...); }
Interface* clone() const override { return new LambdaImpl<Fn>(fFn); }
private:
Fn fFn;
};
class FnPtrImpl final : public Interface {
public:
FnPtrImpl(R (*fn)(Args...)) : fFn(fn) {}
R call(Args... args) const override { return fFn(skstd::forward<Args>(args)...); }
Interface* clone() const override { return new FnPtrImpl(fFn); }
private:
R (*fFn)(Args...);
};
skstd::unique_ptr<Interface> fFunction;
};
#endif//SkFunction_DEFINED
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