relationship.h

//
// Copyright 2016 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_RELATIONSHIP_H
#define PXR_USD_USD_RELATIONSHIP_H

#include "pxr/pxr.h"
#include "pxr/usd/usd/api.h"
#include "pxr/usd/usd/common.h"
#include "pxr/usd/usd/property.h"

#include "pxr/usd/sdf/path.h"
#include "pxr/base/vt/value.h"

#include <string>
#include <vector>

PXR_NAMESPACE_OPEN_SCOPE


class UsdRelationship;

typedef std::vector<UsdRelationship> UsdRelationshipVector;

class UsdRelationship : public UsdProperty {
public:
    UsdRelationship() : UsdProperty(_Null<UsdRelationship>()) {}


    // XXX Should the mutation API be changed to take UsdObject
    // pointers so that we can enforce (as does Mf) that you can only
    // target extant scenegraph objects? (Note the API would still need to
    // validate those objects since it is easy to create a UsdAttribute
    // or UsdRelationship object not backed by scene description).

    USD_API
    bool AddTarget(const SdfPath& target,
           UsdListPosition position=UsdListPositionBackOfPrependList) const;

    USD_API
    bool RemoveTarget(const SdfPath& target) const;

    USD_API
    bool SetTargets(const SdfPathVector& targets) const;

    USD_API
    bool ClearTargets(bool removeSpec) const;

    USD_API
    bool GetTargets(SdfPathVector* targets) const;

    USD_API
    bool GetForwardedTargets(SdfPathVector* targets) const;

    USD_API
    bool HasAuthoredTargets() const;


private:
    friend class UsdObject;
    friend class UsdPrim;
    friend class Usd_PrimData;
    template <class A0, class A1>
    friend struct UsdPrim_TargetFinder;

    UsdRelationship(const Usd_PrimDataHandle &prim,
                    const SdfPath &proxyPrimPath,
                    const TfToken& relName)
        : UsdProperty(UsdTypeRelationship, prim, proxyPrimPath, relName) {}

    UsdRelationship(UsdObjType objType,
                    const Usd_PrimDataHandle &prim,
                    const SdfPath &proxyPrimPath,
                    const TfToken &propName)
        : UsdProperty(objType, prim, proxyPrimPath, propName) {}

    SdfRelationshipSpecHandle _CreateSpec(bool fallbackCustom=true) const;
    bool _Create(bool fallbackCustom) const;

    bool _GetForwardedTargets(SdfPathVector* targets,
                              bool includeForwardingRels) const;

    bool _GetForwardedTargetsImpl(SdfPathSet* visited, 
                                  SdfPathSet* uniqueTargets,
                                  SdfPathVector* targets,
                                  bool *foundAnyErrors,
                                  bool includeForwardingRels) const;

    SdfPath _GetTargetForAuthoring(const SdfPath &targetPath,
                                   std::string* whyNot = 0) const;
};


PXR_NAMESPACE_CLOSE_SCOPE

#endif //PXR_USD_USD_RELATIONSHIP_H