lib/shared/include/unicode/uobject.h

   1 /*
   2 ******************************************************************************
   3 *
   4 *   Copyright (C) 2002-2012, International Business Machines
   5 *   Corporation and others.  All Rights Reserved.
   6 *
   7 ******************************************************************************
   8 *   file name:  uobject.h
   9 *   encoding:   US-ASCII
  10 *   tab size:   8 (not used)
  11 *   indentation:4
  12 *
  13 *   created on: 2002jun26
  14 *   created by: Markus W. Scherer
  15 */
  16
  17 #ifndef __UOBJECT_H__
  18 #define __UOBJECT_H__
  19
  20 #include "unicode/utypes.h"
  21
  22 /**
  23  * \file
  24  * \brief C++ API: Common ICU base class UObject.
  25  */
  26
  27 /**
  28  * @{
  29  * \def U_NO_THROW
  30  *         Define this to define the throw() specification so
  31  *                 certain functions do not throw any exceptions
  32  *
  33  *         UMemory operator new methods should have the throw() specification
  34  *         appended to them, so that the compiler adds the additional NULL check
  35  *         before calling constructors. Without, if <code>operator new</code> returns NULL the
  36  *         constructor is still called, and if the constructor references member
  37  *         data, (which it typically does), the result is a segmentation violation.
  38  *
  39  * @stable ICU 4.2
  40  */
  41 #ifndef U_NO_THROW
  42 #define U_NO_THROW throw()
  43 #endif
  44
  45 /** @} */
  46
  47 /*===========================================================================*/
  48 /* UClassID-based RTTI */
  49 /*===========================================================================*/
  50
  51 /**
  52  * UClassID is used to identify classes without using the compiler's RTTI.
  53  * This was used before C++ compilers consistently supported RTTI.
  54  * ICU 4.6 requires compiler RTTI to be turned on.
  55  *
  56  * Each class hierarchy which needs
  57  * to implement polymorphic clone() or operator==() defines two methods,
  58  * described in detail below.  UClassID values can be compared using
  59  * operator==(). Nothing else should be done with them.
  60  *
  61  * \par
  62  * In class hierarchies that implement "poor man's RTTI",
  63  * each concrete subclass implements getDynamicClassID() in the same way:
  64  *
  65  * \code
  66  *      class Derived {
  67  *      public:
  68  *          virtual UClassID getDynamicClassID() const
  69  *            { return Derived::getStaticClassID(); }
  70  *      }
  71  * \endcode
  72  *
  73  * Each concrete class implements getStaticClassID() as well, which allows
  74  * clients to test for a specific type.
  75  *
  76  * \code
  77  *      class Derived {
  78  *      public:
  79  *          static UClassID U_EXPORT2 getStaticClassID();
  80  *      private:
  81  *          static char fgClassID;
  82  *      }
  83  *
  84  *      // In Derived.cpp:
  85  *      UClassID Derived::getStaticClassID()
  86  *        { return (UClassID)&Derived::fgClassID; }
  87  *      char Derived::fgClassID = 0; // Value is irrelevant
  88  * \endcode
  89  * @stable ICU 2.0
  90  */
  91 typedef void* UClassID;
  92
  93 U_NAMESPACE_BEGIN
  94
  95 /**
  96  * UMemory is the common ICU base class.
  97  * All other ICU C++ classes are derived from UMemory (starting with ICU 2.4).
  98  *
  99  * This is primarily to make it possible and simple to override the
 100  * C++ memory management by adding new/delete operators to this base class.
 101  *
 102  * To override ALL ICU memory management, including that from plain C code,
 103  * replace the allocation functions declared in cmemory.h
 104  *
 105  * UMemory does not contain any virtual functions.
 106  * Common "boilerplate" functions are defined in UObject.
 107  *
 108  * @stable ICU 2.4
 109  */
 110 class U_COMMON_API UMemory {
 111 public:
 112
 113 /* test versions for debugging shaper heap memory problems */
 114 #ifdef SHAPER_MEMORY_DEBUG
 115     static void * NewArray(int size, int count);
 116     static void * GrowArray(void * array, int newSize );
 117     static void   FreeArray(void * array );
 118 #endif
 119
 120 #if U_OVERRIDE_CXX_ALLOCATION
 121     /**
 122      * Override for ICU4C C++ memory management.
 123      * simple, non-class types are allocated using the macros in common/cmemory.h
 124      * (uprv_malloc(), uprv_free(), uprv_realloc());
 125      * they or something else could be used here to implement C++ new/delete
 126      * for ICU4C C++ classes
 127      * @stable ICU 2.4
 128      */
 129     static void * U_EXPORT2 operator new(size_t size) U_NO_THROW;
 130
 131     /**
 132      * Override for ICU4C C++ memory management.
 133      * See new().
 134      * @stable ICU 2.4
 135      */
 136     static void * U_EXPORT2 operator new[](size_t size) U_NO_THROW;
 137
 138     /**
 139      * Override for ICU4C C++ memory management.
 140      * simple, non-class types are allocated using the macros in common/cmemory.h
 141      * (uprv_malloc(), uprv_free(), uprv_realloc());
 142      * they or something else could be used here to implement C++ new/delete
 143      * for ICU4C C++ classes
 144      * @stable ICU 2.4
 145      */
 146     static void U_EXPORT2 operator delete(void *p) U_NO_THROW;
 147
 148     /**
 149      * Override for ICU4C C++ memory management.
 150      * See delete().
 151      * @stable ICU 2.4
 152      */
 153     static void U_EXPORT2 operator delete[](void *p) U_NO_THROW;
 154
 155 #if U_HAVE_PLACEMENT_NEW
 156     /**
 157      * Override for ICU4C C++ memory management for STL.
 158      * See new().
 159      * @stable ICU 2.6
 160      */
 161     static inline void * U_EXPORT2 operator new(size_t, void *ptr) U_NO_THROW { return ptr; }
 162
 163     /**
 164      * Override for ICU4C C++ memory management for STL.
 165      * See delete().
 166      * @stable ICU 2.6
 167      */
 168     static inline void U_EXPORT2 operator delete(void *, void *) U_NO_THROW {}
 169 #endif /* U_HAVE_PLACEMENT_NEW */
 170 #if U_HAVE_DEBUG_LOCATION_NEW
 171     /**
 172       * This method overrides the MFC debug version of the operator new
 173       *
 174       * @param size   The requested memory size
 175       * @param file   The file where the allocation was requested
 176       * @param line   The line where the allocation was requested
 177       */
 178     static void * U_EXPORT2 operator new(size_t size, const char* file, int line) U_NO_THROW;
 179     /**
 180       * This method provides a matching delete for the MFC debug new
 181       *
 182       * @param p      The pointer to the allocated memory
 183       * @param file   The file where the allocation was requested
 184       * @param line   The line where the allocation was requested
 185       */
 186     static void U_EXPORT2 operator delete(void* p, const char* file, int line) U_NO_THROW;
 187 #endif /* U_HAVE_DEBUG_LOCATION_NEW */
 188 #endif /* U_OVERRIDE_CXX_ALLOCATION */
 189
 190     /*
 191      * Assignment operator not declared. The compiler will provide one
 192      * which does nothing since this class does not contain any data members.
 193      * API/code coverage may show the assignment operator as present and
 194      * untested - ignore.
 195      * Subclasses need this assignment operator if they use compiler-provided
 196      * assignment operators of their own. An alternative to not declaring one
 197      * here would be to declare and empty-implement a protected or public one.
 198     UMemory &UMemory::operator=(const UMemory &);
 199      */
 200 };
 201
 202 /**
 203  * UObject is the common ICU "boilerplate" class.
 204  * UObject inherits UMemory (starting with ICU 2.4),
 205  * and all other public ICU C++ classes
 206  * are derived from UObject (starting with ICU 2.2).
 207  *
 208  * UObject contains common virtual functions, in particular a virtual destructor.
 209  *
 210  * The clone() function is not available in UObject because it is not
 211  * implemented by all ICU classes.
 212  * Many ICU services provide a clone() function for their class trees,
 213  * defined on the service's C++ base class, and all subclasses within that
 214  * service class tree return a pointer to the service base class
 215  * (which itself is a subclass of UObject).
 216  * This is because some compilers do not support covariant (same-as-this)
 217  * return types; cast to the appropriate subclass if necessary.
 218  *
 219  * @stable ICU 2.2
 220  */
 221 class U_COMMON_API UObject : public UMemory {
 222 public:
 223     /**
 224      * Destructor.
 225      *
 226      * @stable ICU 2.2
 227      */
 228     virtual ~UObject();
 229
 230     /**
 231      * ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.
 232      * The base class implementation returns a dummy value.
 233      *
 234      * Use compiler RTTI rather than ICU's "poor man's RTTI".
 235      * Since ICU 4.6, new ICU C++ class hierarchies do not implement "poor man's RTTI".
 236      *
 237      * @stable ICU 2.2
 238      */
 239     virtual UClassID getDynamicClassID() const;
 240
 241 protected:
 242     // the following functions are protected to prevent instantiation and
 243     // direct use of UObject itself
 244
 245     // default constructor
 246     // inline UObject() {}
 247
 248     // copy constructor
 249     // inline UObject(const UObject &other) {}
 250
 251 #if 0
 252     // TODO Sometime in the future. Implement operator==().
 253     // (This comment inserted in 2.2)
 254     // some or all of the following "boilerplate" functions may be made public
 255     // in a future ICU4C release when all subclasses implement them
 256
 257     // assignment operator
 258     // (not virtual, see "Taligent's Guide to Designing Programs" pp.73..74)
 259     // commented out because the implementation is the same as a compiler's default
 260     // UObject &operator=(const UObject &other) { return *this; }
 261
 262     // comparison operators
 263     virtual inline UBool operator==(const UObject &other) const { return this==&other; }
 264     inline UBool operator!=(const UObject &other) const { return !operator==(other); }
 265
 266     // clone() commented out from the base class:
 267     // some compilers do not support co-variant return types
 268     // (i.e., subclasses would have to return UObject * as well, instead of SubClass *)
 269     // see also UObject class documentation.
 270     // virtual UObject *clone() const;
 271 #endif
 272
 273     /*
 274      * Assignment operator not declared. The compiler will provide one
 275      * which does nothing since this class does not contain any data members.
 276      * API/code coverage may show the assignment operator as present and
 277      * untested - ignore.
 278      * Subclasses need this assignment operator if they use compiler-provided
 279      * assignment operators of their own. An alternative to not declaring one
 280      * here would be to declare and empty-implement a protected or public one.
 281     UObject &UObject::operator=(const UObject &);
 282      */
 283 };
 284
 285 #ifndef U_HIDE_INTERNAL_API
 286 /**
 287  * This is a simple macro to add ICU RTTI to an ICU object implementation.
 288  * This does not go into the header. This should only be used in *.cpp files.
 289  *
 290  * @param myClass The name of the class that needs RTTI defined.
 291  * @internal
 292  */
 293 #define UOBJECT_DEFINE_RTTI_IMPLEMENTATION(myClass) \
 294     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 295         static char classID = 0; \
 296         return (UClassID)&classID; \
 297     } \
 298     UClassID myClass::getDynamicClassID() const \
 299     { return myClass::getStaticClassID(); }
 300
 301
 302 /**
 303  * This macro adds ICU RTTI to an ICU abstract class implementation.
 304  * This macro should be invoked in *.cpp files.  The corresponding
 305  * header should declare getStaticClassID.
 306  *
 307  * @param myClass The name of the class that needs RTTI defined.
 308  * @internal
 309  */
 310 #define UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(myClass) \
 311     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 312         static char classID = 0; \
 313         return (UClassID)&classID; \
 314     }
 315
 316 #endif  /* U_HIDE_INTERNAL_API */
 317
 318 U_NAMESPACE_END
 319
 320 #endif