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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_ZUCCHINI_TYPED_VALUE_H_
#define COMPONENTS_ZUCCHINI_TYPED_VALUE_H_
#include <ostream>
namespace zucchini {
// Strong typed values, with compare and convert functions for underlying data.
// Typically one would use strongly typed enums for this. However, for Zucchini,
// the number of bytes is not fixed, and must be represented as an integer for
// iteration.
// |Tag| is a type tag used to uniquely identify TypedValue.
// |T| is an integral type used to hold values.
// Example:
// struct Foo : TypedValue<Foo, int> {
// using Foo::TypedValue::TypedValue; // inheriting constructor.
// };
// Foo will be used to hold values of type |int|, but with a distinct type from
// any other TypedValue.
template <class Tag, class T>
class TypedValue {
public:
constexpr TypedValue() = default;
explicit constexpr TypedValue(const T& value) : value_(value) {}
explicit operator T() const { return value_; }
const T value() const { return value_; }
friend bool operator==(const TypedValue& a, const TypedValue& b) {
return a.value_ == b.value_;
}
friend bool operator!=(const TypedValue& a, const TypedValue& b) {
return !(a == b);
}
friend bool operator<(const TypedValue& a, const TypedValue& b) {
return a.value_ < b.value_;
}
friend bool operator>(const TypedValue& a, const TypedValue& b) {
return b < a;
}
private:
T value_ = {};
};
template <class Tag, class T>
std::ostream& operator<<(std::ostream& os, const TypedValue<Tag, T>& tag) {
return os << tag.value();
}
} // namespace zucchini
#endif // COMPONENTS_ZUCCHINI_TYPED_VALUE_H_
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