scoped.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_BASE_TF_SCOPED_H
#define PXR_BASE_TF_SCOPED_H

#include "pxr/pxr.h"

#include <functional>

PXR_NAMESPACE_OPEN_SCOPE

template <typename T = std::function<void ()> >
class TfScoped {
    TfScoped(TfScoped const &) = delete;
    TfScoped &operator=(TfScoped const &) = delete;
public:
    typedef T Procedure;

    explicit TfScoped(const Procedure& leave) : _onExit(leave) { }

    ~TfScoped() { _onExit(); }

private:
    // Can't put these on the heap.  No implementation needed.
    static void *operator new(::std::size_t size);

private:
    Procedure _onExit;
};

// Specialization of TfScoped for member functions.
template <typename T>
class TfScoped<void (T::*)()> {
    TfScoped(TfScoped const &) = delete;
    TfScoped &operator=(TfScoped const &) = delete;
public:
    typedef void (T::*Procedure)();

    explicit TfScoped(T* obj, const Procedure& leave) :
        _obj(obj), _onExit(leave) { }

    ~TfScoped() { (_obj->*_onExit)(); }

private:
    // Can't put these on the heap.  No implementation needed.
    static void *operator new(::std::size_t size);

private:
    T* _obj;
    Procedure _onExit;
};

// Specialization of TfScoped for functions taking one pointer argument.
template <typename T>
class TfScoped<void (*)(T*)> {
    TfScoped(TfScoped const &) = delete;
    TfScoped &operator=(TfScoped const &) = delete;
public:
    typedef void (*Procedure)(T*);

    explicit TfScoped(const Procedure& leave, T* obj) :
        _obj(obj), _onExit(leave) { }

    ~TfScoped() { _onExit(_obj); }

private:
    // Can't put these on the heap.  No implementation needed.
    static void *operator new(::std::size_t size);

private:
    T* _obj;
    Procedure _onExit;
};

template <typename T>
class TfScopedVar {
    TfScopedVar(TfScopedVar const &) = delete;
    TfScopedVar &operator=(TfScopedVar const &) = delete;
public:
    explicit TfScopedVar(T& x, const T& val) :
        _x(&x),
        _old(x)
    {
        x = val;
    }

    ~TfScopedVar() { *_x = _old; }

private:
    // Can't put these on the heap.  No implementation needed.
    static void *operator new(::std::size_t size);

private:
    T* _x;
    T _old;
};

class TfScopedAutoVar {
    TfScopedAutoVar(TfScopedAutoVar const &) = delete;
    TfScopedAutoVar &operator=(TfScopedAutoVar const &) = delete;
public:
    template <typename T>
    explicit TfScopedAutoVar(T& x, const T& val) :
        _scope(std::bind(&TfScopedAutoVar::_Set<T>, &x, x))
    {
        x = val;
    }

private:
    // Restore value function
    template <typename T>
    static void _Set(T* x, const T& val)
    {
        *x = val;
    }

    // Can't put these on the heap.  No implementation needed.
    static void *operator new(::std::size_t size);

private:
    TfScoped<> _scope;
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif // PXR_BASE_TF_SCOPED_H