expressionVariables.h

//
// Copyright 2023 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_USD_PCP_EXPRESSION_VARIABLES_H
#define PXR_USD_PCP_EXPRESSION_VARIABLES_H
 
#include "pxr/pxr.h"
#include "pxr/usd/pcp/api.h"
#include "pxr/usd/pcp/layerStackIdentifier.h"
#include "pxr/usd/pcp/expressionVariablesSource.h"
 
#include "pxr/base/vt/dictionary.h"
 
#include <utility>
#include <unordered_map>
 
PXR_NAMESPACE_OPEN_SCOPE
 
class PcpExpressionVariables
{
public:
    PCP_API
    static PcpExpressionVariables
    Compute(
        const PcpLayerStackIdentifier& sourceLayerStackId,
        const PcpLayerStackIdentifier& rootLayerStackId,
        const PcpExpressionVariables* overrideExpressionVars = nullptr);
 
    PcpExpressionVariables() = default;
 
    PcpExpressionVariables(
        const PcpExpressionVariablesSource& source,
        const VtDictionary& expressionVariables)
        : PcpExpressionVariables(
            PcpExpressionVariablesSource(source),
            VtDictionary(expressionVariables))
    { }
 
    PcpExpressionVariables(
        PcpExpressionVariablesSource&& source,
        VtDictionary&& expressionVariables)
        : _source(std::move(source))
        , _expressionVariables(std::move(expressionVariables))
    { }
 
    bool operator==(const PcpExpressionVariables& rhs) const
    { 
        return (this == &rhs) || 
        (std::tie(_source, _expressionVariables) == 
         std::tie(rhs._source, rhs._expressionVariables));
    }
 
    bool operator!=(const PcpExpressionVariables& rhs) const
    { 
        return !(*this == rhs);
    }
 
    const PcpExpressionVariablesSource& GetSource() const
    { return _source; }
 
    const VtDictionary& GetVariables() const
    { return _expressionVariables; }
 
    void SetVariables(const VtDictionary& variables)
    { _expressionVariables = variables; }
 
private:
    PcpExpressionVariablesSource _source;
    VtDictionary _expressionVariables;
};
 
// ------------------------------------------------------------
 
class PcpExpressionVariableCachingComposer
{
public:
    PCP_API
    explicit PcpExpressionVariableCachingComposer(
        const PcpLayerStackIdentifier& rootLayerStackIdentifier);
 
    PCP_API
    const PcpExpressionVariables&
    ComputeExpressionVariables(const PcpLayerStackIdentifier& id);
 
private:
    PcpLayerStackIdentifier _rootLayerStackId;
 
    using _IdentifierToExpressionVarsMap = std::unordered_map<
        PcpLayerStackIdentifier, PcpExpressionVariables, TfHash>;
    _IdentifierToExpressionVarsMap _identifierToExpressionVars;
};
 
PXR_NAMESPACE_CLOSE_SCOPE
 
#endif