EncodableToTLV.h

/*
 *    Copyright (c) 2024 Project CHIP Authors
 *    All rights reserved.
 *
 *    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
 *
 *        http://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.
 */

#pragma once

#include <app/data-model/Encode.h>
#include <lib/core/CHIPError.h>
#include <lib/core/TLV.h>

namespace chip {
namespace app {
namespace DataModel {

/// Defines an abstract class of something that can be encoded
/// into a TLV with a given data tag
class EncodableToTLV
{
public:
    virtual ~EncodableToTLV() = default;

    virtual CHIP_ERROR EncodeTo(TLV::TLVWriter & writer, TLV::Tag tag) const = 0;
};

/// An `EncodableToTLV` that uses `DataModel::Encode` to encode things in one call.
///
/// Applicable to any type for which `chip::app::DataModel::Encode` works. In
/// particular, types like <ClusterName>::Commands::<CommandName>::Type
/// can be used as a type here.
template <typename T>
class EncodableType : public EncodableToTLV
{
public:
    /// Encodes the given value via `DataModel::Encode` when the underlying
    /// encode is called.
    ///
    /// LIFETIME NOTE: uses a reference to value, so value must live longer than
    ///                this object.
    EncodableType(const T & value) : mValue(value) {}

    CHIP_ERROR EncodeTo(TLV::TLVWriter & writer, TLV::Tag tag) const override { return DataModel::Encode(writer, tag, mValue); }

private:
    const T & mValue;
};

} // namespace DataModel
} // namespace app
} // namespace chip