109 lines
3.1 KiB
C++
109 lines
3.1 KiB
C++
/*
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* Copyright 2017 WebAssembly Community Group participants
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef WABT_CAST_H_
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#define WABT_CAST_H_
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#include <memory>
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#include <type_traits>
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#include "wabt/common.h"
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// Modeled after LLVM's dynamic casts:
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// http://llvm.org/docs/ProgrammersManual.html#the-isa-cast-and-dyn-cast-templates
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//
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// Use isa<T>(foo) to check whether foo is a T*:
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//
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// if (isa<Minivan>(car)) {
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// ...
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// }
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//
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// Use cast<T>(foo) when you know that foo is a T* -- it will assert that the
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// type matches:
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//
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// switch (car.type) {
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// case CarType::Minivan: {
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// auto minivan = cast<Minivan>(car);
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// ...
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// }
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// }
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//
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// Use dyn_cast<T>(foo) as a combination if isa and cast, it will return
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// nullptr if the type doesn't match:
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//
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// if (auto minivan = dyn_cast<Minivan>(car)) {
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// ...
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// }
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//
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//
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// To use these classes in a type hierarchy, you must implement classof:
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//
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// enum CarType { Minivan, ... };
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// struct Car { CarType type; ... };
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// struct Minivan : Car {
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// static bool classof(const Car* car) { return car->type == Minivan; }
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// ...
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// };
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//
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namespace wabt {
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template <typename Derived, typename Base>
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bool isa(const Base* base) {
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WABT_STATIC_ASSERT((std::is_base_of<Base, Derived>::value));
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return Derived::classof(base);
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}
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template <typename Derived, typename Base>
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const Derived* cast(const Base* base) {
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assert(isa<Derived>(base));
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return static_cast<const Derived*>(base);
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};
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template <typename Derived, typename Base>
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Derived* cast(Base* base) {
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assert(isa<Derived>(base));
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return static_cast<Derived*>(base);
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};
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template <typename Derived, typename Base>
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const Derived* dyn_cast(const Base* base) {
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return isa<Derived>(base) ? static_cast<const Derived*>(base) : nullptr;
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};
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template <typename Derived, typename Base>
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Derived* dyn_cast(Base* base) {
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return isa<Derived>(base) ? static_cast<Derived*>(base) : nullptr;
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};
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// Cast functionality for unique_ptr. isa and dyn_cast are not included because
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// they won't always pass ownership back to the caller.
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template <typename Derived, typename Base>
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std::unique_ptr<const Derived> cast(std::unique_ptr<const Base>&& base) {
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assert(isa<Derived>(base.get()));
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return std::unique_ptr<Derived>(static_cast<const Derived*>(base.release()));
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};
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template <typename Derived, typename Base>
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std::unique_ptr<Derived> cast(std::unique_ptr<Base>&& base) {
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assert(isa<Derived>(base.get()));
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return std::unique_ptr<Derived>(static_cast<Derived*>(base.release()));
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};
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} // namespace wabt
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#endif // WABT_CAST_H_
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