android/android-emu/android/base/files/ScopedRegKey.h

// Copyright 2014 The Android Open Source Project
//
// This software is licensed under the terms of the GNU General Public
// License version 2, as published by the Free Software Foundation, and
// may be copied, distributed, and modified under those terms.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

#pragma once

#if !defined(_WIN32) && !defined(_WIN64)
#error "Only compile this file when targetting Windows!"
#endif

#include "android/base/Compiler.h"
#include <algorithm>

#define WIN32_LEAN_AND_MEAN 1
#include <windows.h>

namespace android {
namespace base {

// Helper class used to wrap a Win32 HKEY that will be closed when
// the instance is destroyed, unless the release() method was called
// before that.
class ScopedRegKey {
public:
    // Default destructor is used to wrap an invalid HKEY value.
    ScopedRegKey() : hkey_(0), valid_(false) {}

    // Constructor takes ownership of |HKEY|.
    explicit ScopedRegKey(HKEY hkey) : hkey_(hkey), valid_(true) {}

    // Constructor takes ownership of |HKEY|.
    explicit ScopedRegKey(HKEY hkey, bool valid_) : hkey_(hkey), valid_(valid_) {}

    // Destructor calls close() method.
    ~ScopedRegKey() { close(); }

    // Returns true iff the wrapped HKEY value is valid.
    bool valid() const { return valid_; }

    // Return current HKEY value.  undefined if !valid_
    HKEY get() const { return hkey_; }

    // Return current HKEY value, transferring ownership to the caller.
    HKEY release() {
        HKEY h = hkey_;
        hkey_ = 0;
        valid_ = false;
        return h;
    }

    // Close HKEY if it is not invalid.
    void close() {
        if (valid_) {
            ::RegCloseKey(hkey_);
            hkey_ = 0;
            valid_ = false;
        }
    }

    // Swap the content of two ScopedRegKey instances.
    void swap(ScopedRegKey* other) {
        std::swap(hkey_, other->hkey_);
        std::swap(valid_, other->valid_);
    }

private:
    DISALLOW_COPY_AND_ASSIGN(ScopedRegKey);

    HKEY hkey_;
    bool valid_;
};

}  // namespace base
}  // namespace android