resolveTarget.h

//
// Copyright 2022 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_USD_USD_RESOLVE_TARGET_H
#define PXR_USD_USD_RESOLVE_TARGET_H

#include "pxr/pxr.h"
#include "pxr/usd/usd/api.h"
#include "pxr/usd/pcp/node.h"
#include "pxr/usd/pcp/primIndex.h"
#include "pxr/usd/sdf/declareHandles.h"

#include <memory>

PXR_NAMESPACE_OPEN_SCOPE

SDF_DECLARE_HANDLES(SdfLayer);

class UsdResolveTarget {

public:
    UsdResolveTarget() = default;

    const PcpPrimIndex *GetPrimIndex() const {
        return _expandedPrimIndex.get();
    }

    USD_API
    PcpNodeRef GetStartNode() const;

    USD_API
    SdfLayerHandle GetStartLayer() const;

    USD_API
    PcpNodeRef GetStopNode() const;

    USD_API
    SdfLayerHandle GetStopLayer() const;

    bool IsNull() const {
        return !bool(_expandedPrimIndex);
    }

private:
    // Non-null UsdResolveTargets can only be created by functions in UsdPrim 
    // and UsdPrimCompositionQueryArc.
    friend class UsdPrim;
    friend class UsdPrimCompositionQueryArc;

    // Usd_Resolver wants to access the iterators provided by this target.
    friend class Usd_Resolver;

    USD_API
    UsdResolveTarget(
        const std::shared_ptr<PcpPrimIndex> &index, 
        const PcpNodeRef &node, 
        const SdfLayerHandle &layer);

    USD_API
    UsdResolveTarget(
        const std::shared_ptr<PcpPrimIndex> &index, 
        const PcpNodeRef &node, 
        const SdfLayerHandle &layer,
        const PcpNodeRef &stopNode, 
        const SdfLayerHandle &stopLayer);

    // Resolve targets are created with an expanded prim index either from
    // a composition query (which owns and holds it) or from a UsdPrim (which
    // creates it solely to create the resolve target). The expanded prim index
    // is not otherwise cached, so we have to hold on to it during the lifetime
    // of the resolve target.
    std::shared_ptr<PcpPrimIndex> _expandedPrimIndex;
    PcpNodeRange _nodeRange;

    PcpNodeIterator _startNodeIt;
    SdfLayerRefPtrVector::const_iterator _startLayerIt;
    PcpNodeIterator _stopNodeIt;
    SdfLayerRefPtrVector::const_iterator _stopLayerIt;
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif // PXR_USD_USD_RESOLVE_TARGET_H