/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* OSBoolean.cpp created by rsulack on Tue Oct 12 1999 */

#ifndef _OS_OSBOOLEAN_H
#define _OS_OSBOOLEAN_H

#include <libkern/c++/OSObject.h>

class OSString;

/*!
 * @header
 *
 * @abstract
 * This header declares the OSBoolean container class.
 */
 

/*!
 * @class OSBoolean
 *
 * @abstract
 * OSBoolean wraps a boolean value in a C++ object
 * for use in Libkern collections.
 *
 * @discussion
 * OSBoolean represents a boolean <code>true</code>/<code>false</code> value
 * as a Libkern C++ object.
 * There are only two instances of OSBoolean,
 * <code>@link kOSBooleanTrue kOSBooleanTrue@/link</code>
 * and <code>@link kOSBooleanFalse kOSBooleanFalse@/link</code>.
 * These are shared globally and returned by the instance-creation function
 * <code>@link withBoolean withBoolean@/link</code>.
 * Thus, you can use pointer comparison
 * to test whether two OSBoolean objects are equal.
 */
class OSBoolean : public OSObject
{
    OSDeclareDefaultStructors(OSBoolean)

protected:
    bool value;

   /*!
    * @function taggedRelease
    *
    * @abstract
    * Overrides the reference counting mechanism
    * for the shared global instances.
    *
    * @param tag  Unused. 
    * @param when Unused. 
    */
    virtual void taggedRelease(
        const void * tag,
        const int    when) const;

public:
    static void initialize();

   /*!
    * @function withBoolean
    *
    * @abstract
    * Returns one of the global instances of OSBoolean.
    *
    * @param value   A boolean value.
    *
    * @result
    * The global instance of OSBoolean with the boolean <code>value</code>.
    *
    * @discussion
    * This function actually returns either
    * <code>@link kOSBooleanTrue kOSBooleanTrue@/link</code> or
    * <code>@link kOSBooleanFalse kOSBooleanFalse@/link</code>,
    * so that you can always use pointer comparison with OSBoolean objects.
    */
    static OSBoolean * withBoolean(bool value);

   /*!
    * @function free
    *
    * @abstract
    * Overridden to prevent deallocation of the shared global instances.
    *
    * @discussion
    * This function should never be called.
    */
    virtual void free();


   /*!
    * @function taggedRetain
    *
    * @abstract
    * Overrides the reference counting mechanism for the shared global instances.
    *
    * @param tag  Unused. 
    */
    virtual void taggedRetain(const void * tag) const;


   /*!
    * @function isTrue
    *
    * @abstract
    * Checks whether the OSBoolean object
    * represents a <code>true</code> <code>bool</code> value.
    *
    * @result
    * <code>true</code> if the OSBoolean object is <code>true</code>,
    * <code>false</code> otherwise.
    *
    * @discussion
    * You can also use <code>==</code> against
    * <code>@link kOSBooleanTrue kOSBooleanTrue@/link</code>.
    */
    virtual bool isTrue() const;


   /*!
    * @function isFalse
    *
    * @abstract
    * Checks whether the OSBoolean object
    * represents a <code>false</code> <code>bool</code> value.
    *
    * @result
    * <code>true</code> if the OSBoolean object is <code>false</code>,
    * <code>true</code> otherwise.
    *
    * @discussion
    * You can also use <code>==</code> against
    * <code>@link kOSBooleanFalse kOSBooleanFalse@/link</code>.
    */
    virtual bool isFalse() const;


   /*!
    * @function getValue
    *
    * @abstract
    * Returns the C++ <code>bool</code> value for the OSBoolean object.
    *
    * @result
    * Returns the C++ <code>bool</code> value of the OSBoolean object. 
    */
    virtual bool getValue() const;


   /*!
    * @function isEqualTo
    *
    * @abstract
    * Tests the equality of two OSBoolean objects.
    *
    * @param aBoolean    The OSBoolean to be compared against the receiver.
    *
    * @result
    * <code>true</code> if the OSBoolean objects are equal,
    * <code>false</code> if not.
    *
    * @discussion
    * Two OSBoolean objects are considered equal
    * if they are the same exact object (pointer equality).
    */
    virtual bool isEqualTo(const OSBoolean * aBoolean) const;


   /*!
    * @function isEqualTo
    *
    * @abstract
    * Tests the equality an OSBoolean to an arbitrary object.
    *
    * @param anObject  An object to be compared against the receiver.
    *
    * @result
    * <code>true</code> if the objects are equal, <code>false</code> if not.
    *
    * @discussion
    * An OSBoolean is considered equal to another object
    * if that object is derived from OSBoolean
    * and represents the same C++ <code>bool</code> value.
    */
    virtual bool isEqualTo(const OSMetaClassBase * anObject) const;


   /*!
    * @function serialize
    *
    * @abstract
    * Archives the receiver into the provided
    * @link //apple_ref/doc/class/OSSerialize OSSerialize@/link object.
    *
    * @param serializer  The OSSerialize object.
    *
    * @result
    * <code>true</code> if serialization succeeds, <code>false</code> if not.
    */
    virtual bool serialize(OSSerialize * serializer) const;

    OSMetaClassDeclareReservedUnused(OSBoolean, 0);
    OSMetaClassDeclareReservedUnused(OSBoolean, 1);
    OSMetaClassDeclareReservedUnused(OSBoolean, 2);
    OSMetaClassDeclareReservedUnused(OSBoolean, 3);
    OSMetaClassDeclareReservedUnused(OSBoolean, 4);
    OSMetaClassDeclareReservedUnused(OSBoolean, 5);
    OSMetaClassDeclareReservedUnused(OSBoolean, 6);
    OSMetaClassDeclareReservedUnused(OSBoolean, 7);
};

/*!
 * @const kOSBoolean<code>true</code>
 *
 * @abstract
 * The OSBoolean constant for <code>true</code>.
 *
 * @discussion
 * The OSBoolean constant for <code>true</code>.
 * This object does not need to be retained or released (but it can be).
 * Comparisons of the form
 * booleanObject == kOSBooleanTrue</code> are acceptable
 * and are equivalent to 
 * <code>booleanObject->getValue() == true</code>.
 */
extern OSBoolean * const & kOSBooleanTrue;

/*!
 * @const kOSBoolean<code>false</code>
 *
 * @abstract
 * The OSBoolean constant for <code>false</code>.
 *
 * @discussion
 * The OSBoolean constant for <code>false</code>.
 * This object does not need to be retained or released (but it can be).
 * Comparisons of the form
 * <code>booleanObject == kOSBooleanFalse</code>
 * are acceptable and are equivalent to
 * <code>booleanObject->getValue() == <code>false</code>.
 */
extern OSBoolean * const & kOSBooleanFalse;

#endif /* !_OS_OSBOOLEAN_H */