extComputationContext.h

//
// Copyright 2017 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_IMAGING_HD_EXT_COMPUTATION_CONTEXT_H
#define PXR_IMAGING_HD_EXT_COMPUTATION_CONTEXT_H
 
#include "pxr/pxr.h"
#include "pxr/imaging/hd/api.h"
#include "pxr/base/vt/value.h"
 
PXR_NAMESPACE_OPEN_SCOPE
 
class HdExtComputationContext {
public:
    HdExtComputationContext() = default;
    virtual ~HdExtComputationContext();
 
    virtual const VtValue &GetInputValue(const TfToken &name) const = 0;
 
    template <typename T>
    T GetTypedInputValue(const TfToken &name) const;
    
    virtual const VtValue *GetOptionalInputValuePtr(
                                                 const TfToken &name) const = 0;
 
    template <typename T>
    const T *GetOptionalTypedInputValuePtr(const TfToken &name) const;
 
    virtual void SetOutputValue(const TfToken &name, const VtValue &output) = 0;
 
    template <typename T>
    void SetTypedOutputValue(const TfToken &name, const T &output);
 
    virtual void RaiseComputationError() = 0;
 
private:
    HdExtComputationContext(const HdExtComputationContext &)           = delete;
    HdExtComputationContext &operator = (const HdExtComputationContext &)
                                                                       = delete;
};
 
template <typename T>
T
HdExtComputationContext::GetTypedInputValue(const TfToken &name) const
{
    const VtValue &v = GetInputValue(name);
    if (!v.IsHolding<T>()) {
        TF_CODING_ERROR(
            "HdExtComputationContext::GetTypedInputValue<T> called with type T"
            "not matching the type of the input value for '%s'.",
            name.GetText());
        return {};
    }
 
    return v.UncheckedGet<T>();
}
 
template <typename T>
const T *
HdExtComputationContext::GetOptionalTypedInputValuePtr(const TfToken &name) const
{
    const VtValue * const v = GetOptionalInputValuePtr(name);
    if (!v) {
        return nullptr;
    }
   
    if (!v->IsHolding<T>()) {
        TF_CODING_ERROR(
            "HdExtComputationContext::GetOptionalTypedInputValue<T> called with "
            "type T not matching the type of the input value for '%s'.",
            name.GetText());
        return nullptr;
    }
 
    return &(v->UncheckedGet<T>());
}
 
template <typename T>
void
HdExtComputationContext::
SetTypedOutputValue(const TfToken &name, const T &output)
{
    SetOutputValue(name, VtValue(output));
}
 
PXR_NAMESPACE_CLOSE_SCOPE
 
#endif // PXR_IMAGING_HD_EXT_COMPUTATION_CONTEXT_H