//
// Copyright 2017 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//

#ifndef PXR_IMAGING_HD_EXT_COMP_INPUT_SOURCE_H
#define PXR_IMAGING_HD_EXT_COMP_INPUT_SOURCE_H

#include "pxr/pxr.h"
#include "pxr/imaging/hd/api.h"
#include "pxr/imaging/hd/version.h"
#include "pxr/imaging/hd/bufferSource.h"

#include <memory>

PXR_NAMESPACE_OPEN_SCOPE

class VtValue;

///
/// Abstract base class for a Buffer Source that represents a binding to an
/// input to an ExtComputation.
///
///
class Hd_ExtCompInputSource : public HdNullBufferSource {
public:
    /// Constructs the input binding with the name inputName
    HD_API
    Hd_ExtCompInputSource(const TfToken &inputName);

    HD_API
    virtual ~Hd_ExtCompInputSource() = default;

    /// Returns the name of the input.
    HD_API
    virtual TfToken const &GetName() const final;

    /// Returns the value associated with the input.
    HD_API
    virtual const VtValue &GetValue() const = 0;

private:
    TfToken _inputName;

    Hd_ExtCompInputSource()                                            = delete;
    Hd_ExtCompInputSource(const Hd_ExtCompInputSource &)               = delete;
    Hd_ExtCompInputSource &operator = (const Hd_ExtCompInputSource &)  = delete;
};

using Hd_ExtCompInputSourceSharedPtr = 
   std::shared_ptr<Hd_ExtCompInputSource>;
using Hd_ExtCompInputSourceSharedPtrVector =
    std::vector<Hd_ExtCompInputSourceSharedPtr>;


PXR_NAMESPACE_CLOSE_SCOPE

#endif // PXR_IMAGING_HD_EXT_COMP_INPUT_SOURCE_H