libkern/libkern/c++/OSSymbol.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /* IOSymbol.h created by gvdl on Fri 1998-10-30 */
  26 /* IOSymbol must be created through the factory methods and thus is not subclassable. */
  27
  28 #ifndef _OS_OSSYMBOL_H
  29 #define _OS_OSSYMBOL_H
  30
  31 #include <libkern/c++/OSString.h>
  32
  33 /*!
  34     @class OSSymbol
  35     @abstract A container class whose instances represent unique string values.
  36     @discussion
  37     An OSSymbol object represents a unique string value.  When creating an OSSymbol, a string is given and an OSSymbol representing this string is created if none exist for this string.  If a symbol for this string already exists, then a reference to an existing symbol is returned.
  38 */
  39 class OSSymbol : public OSString
  40 {
  41     friend class OSSymbolPool;
  42
  43     OSDeclareAbstractStructors(OSSymbol)
  44
  45 private:
  46     struct ExpansionData { };
  47
  48     /*! @var reserved
  49         Reserved for future use.  (Internal use only)  */
  50     ExpansionData *reserved;
  51
  52     static void initialize();
  53
  54     friend void checkModuleForSymbols(void); /* in catalogue? */
  55
  56     // The string init methods have to be removed from the inheritance.
  57     virtual bool initWithString(const OSString *aString);
  58     virtual bool initWithCString(const char *cString);
  59     virtual bool initWithCStringNoCopy(const char *cString);
  60
  61 protected:
  62     /*!
  63         @function taggedRelease
  64         @abstract Overriden super class release method so we can synchronise with the symbol pool.
  65         @discussion When we release an symbol we need to synchronise the destruction of the object with any potential searches that may be occuring through the family factor methods.  See OSObject::taggedRelease
  66     */
  67     virtual void taggedRelease(const void *tag, const int when) const;
  68
  69     /*!
  70         @function free
  71         @abstract Overriden super class release method so we can synchronise with the symbol pool.
  72         @discussion When we release an symbol we need to synchronise the destruction of the object with any potential searches that may be occuring through the family factor methods.  See OSObject::free
  73     */
  74     virtual void free();
  75
  76 public:
  77     /*!
  78         @function taggedRelease
  79         @abstract Release a tag.
  80         @discussion The C++ language has forced me to override this method even though I have implemented it as { super::taggedRelease(tag) }. It seems that C++ is confused about the appearance of the protected taggedRelease with 2 args and refuses to only inherit one function.  See OSObject::taggedRelease
  81     */
  82     virtual void taggedRelease(const void *tag) const;
  83
  84
  85     /*!
  86         @function withString
  87         @abstract A static constructor function to create an OSSymbol instance from an OSString object or returns an existing OSSymbol object based on the OSString object given.
  88         @param aString An OSString object.
  89         @result Returns a unique OSSymbol object for the string given.
  90     */
  91     static const OSSymbol *withString(const OSString *aString);
  92     /*!
  93         @function withCString
  94         @abstract A static constructor function to create an OSSymbol instance from a simple c-string returns an existing OSSymbol object based on the string object given.
  95         @param cString A c-string.
  96         @result Returns a unique OSSymbol object for the string given.
  97     */
  98     static const OSSymbol *withCString(const char *cString);
  99     /*!
 100         @function withCStringNoCopy
 101         @abstract A static constructor function to create an OSSymbol instance from a simple c-string, but does not copy the string to the container.
 102         @param cString A c-string.
 103         @result Returns a unique OSSymbol object for the string given.
 104     */
 105     static const OSSymbol *withCStringNoCopy(const char *cString);
 106
 107     /*!
 108         @function isEqualTo
 109         @abstract A member function which tests the equality between two OSSymbol objects.  Two OSSymbol objects are only equivalent when their references are identical
 110         @param aSymbol The OSSymbol object to be compared against the receiver.
 111         @result Returns true if the two objects are equivalent, false otherwise.
 112     */
 113     virtual bool isEqualTo(const OSSymbol *aSymbol) const;
 114     /*!
 115         @function isEqualTo
 116         @abstract A member function which tests the equality between an OSSymbol object and a simple c-string.
 117         @param aCString The c-string to be compared against the receiver.
 118         @result Returns true if the OSSymbol's internal string representation is equivalent to the c-string it is being compared against, false otherwise.
 119     */
 120     virtual bool isEqualTo(const char *aCString) const;
 121     /*!
 122         @function isEqualTo
 123         @abstract A member function which tests the equality between an OSSymbol object and and arbitrary OSObject derived object.
 124         @param obj The OSObject derived object to be compared against the receiver.
 125         @result Returns true if the OSSymbol and the OSObject objects are equivalent.
 126     */
 127     virtual bool isEqualTo(const OSMetaClassBase *obj) const;
 128
 129     /* OSRuntime only INTERNAL API - DO NOT USE */
 130     static void checkForPageUnload(void *startAddr, void *endAddr);
 131
 132
 133     OSMetaClassDeclareReservedUnused(OSSymbol, 0);
 134     OSMetaClassDeclareReservedUnused(OSSymbol, 1);
 135     OSMetaClassDeclareReservedUnused(OSSymbol, 2);
 136     OSMetaClassDeclareReservedUnused(OSSymbol, 3);
 137     OSMetaClassDeclareReservedUnused(OSSymbol, 4);
 138     OSMetaClassDeclareReservedUnused(OSSymbol, 5);
 139     OSMetaClassDeclareReservedUnused(OSSymbol, 6);
 140     OSMetaClassDeclareReservedUnused(OSSymbol, 7);
 141 };
 142
 143 #endif /* !_OS_OSSYMBOL_H */