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// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef EMBOSS_RUNTIME_CPP_EMBOSS_CONSTANT_VIEW_H_
#define EMBOSS_RUNTIME_CPP_EMBOSS_CONSTANT_VIEW_H_
#include "runtime/cpp/emboss_maybe.h"
namespace emboss {
namespace support {
// MaybeConstantView is a "view" type that "reads" a value passed into its
// constructor.
//
// This is used internally by generated structure view classes to provide views
// of parameters; in this way, parameters can be treated like fields in the
// generated code.
template <typename ValueT>
class MaybeConstantView {
public:
MaybeConstantView() : value_() {}
constexpr explicit MaybeConstantView(ValueT value) : value_(value) {}
MaybeConstantView(const MaybeConstantView &) = default;
MaybeConstantView(MaybeConstantView &&) = default;
MaybeConstantView &operator=(const MaybeConstantView &) = default;
MaybeConstantView &operator=(MaybeConstantView &&) = default;
~MaybeConstantView() = default;
constexpr ValueT Read() const { return value_.Value(); }
constexpr ValueT UncheckedRead() const { return value_.ValueOrDefault(); }
constexpr bool Ok() const { return value_.Known(); }
private:
::emboss::support::Maybe<ValueT> value_;
};
} // namespace support
} // namespace emboss
#endif // EMBOSS_RUNTIME_CPP_EMBOSS_CONSTANT_VIEW_H_