icuSources/common/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  * getDynamicClassID() is declared in the base class of the hierarchy as
  63  * a pure virtual.  Each concrete subclass implements it in the same way:
  64  *
  65  * \code
  66  *      class Base {
  67  *      public:
  68  *          virtual UClassID getDynamicClassID() const = 0;
  69  *      }
  70  *
  71  *      class Derived {
  72  *      public:
  73  *          virtual UClassID getDynamicClassID() const
  74  *            { return Derived::getStaticClassID(); }
  75  *      }
  76  * \endcode
  77  *
  78  * Each concrete class implements getStaticClassID() as well, which allows
  79  * clients to test for a specific type.
  80  *
  81  * \code
  82  *      class Derived {
  83  *      public:
  84  *          static UClassID U_EXPORT2 getStaticClassID();
  85  *      private:
  86  *          static char fgClassID;
  87  *      }
  88  *
  89  *      // In Derived.cpp:
  90  *      UClassID Derived::getStaticClassID()
  91  *        { return (UClassID)&Derived::fgClassID; }
  92  *      char Derived::fgClassID = 0; // Value is irrelevant
  93  * \endcode
  94  * @stable ICU 2.0
  95  */
  96 typedef void* UClassID;
  97
  98 U_NAMESPACE_BEGIN
  99
 100 /**
 101  * UMemory is the common ICU base class.
 102  * All other ICU C++ classes are derived from UMemory (starting with ICU 2.4).
 103  *
 104  * This is primarily to make it possible and simple to override the
 105  * C++ memory management by adding new/delete operators to this base class.
 106  *
 107  * To override ALL ICU memory management, including that from plain C code,
 108  * replace the allocation functions declared in cmemory.h
 109  *
 110  * UMemory does not contain any virtual functions.
 111  * Common "boilerplate" functions are defined in UObject.
 112  *
 113  * @stable ICU 2.4
 114  */
 115 class U_COMMON_API UMemory {
 116 public:
 117
 118 /* test versions for debugging shaper heap memory problems */
 119 #ifdef SHAPER_MEMORY_DEBUG
 120     static void * NewArray(int size, int count);
 121     static void * GrowArray(void * array, int newSize );
 122     static void   FreeArray(void * array );
 123 #endif
 124
 125 #if U_OVERRIDE_CXX_ALLOCATION
 126     /**
 127      * Override for ICU4C C++ memory management.
 128      * simple, non-class types are allocated using the macros in common/cmemory.h
 129      * (uprv_malloc(), uprv_free(), uprv_realloc());
 130      * they or something else could be used here to implement C++ new/delete
 131      * for ICU4C C++ classes
 132      * @stable ICU 2.4
 133      */
 134     static void * U_EXPORT2 operator new(size_t size) U_NO_THROW;
 135
 136     /**
 137      * Override for ICU4C C++ memory management.
 138      * See new().
 139      * @stable ICU 2.4
 140      */
 141     static void * U_EXPORT2 operator new[](size_t size) U_NO_THROW;
 142
 143     /**
 144      * Override for ICU4C C++ memory management.
 145      * simple, non-class types are allocated using the macros in common/cmemory.h
 146      * (uprv_malloc(), uprv_free(), uprv_realloc());
 147      * they or something else could be used here to implement C++ new/delete
 148      * for ICU4C C++ classes
 149      * @stable ICU 2.4
 150      */
 151     static void U_EXPORT2 operator delete(void *p) U_NO_THROW;
 152
 153     /**
 154      * Override for ICU4C C++ memory management.
 155      * See delete().
 156      * @stable ICU 2.4
 157      */
 158     static void U_EXPORT2 operator delete[](void *p) U_NO_THROW;
 159
 160 #if U_HAVE_PLACEMENT_NEW
 161     /**
 162      * Override for ICU4C C++ memory management for STL.
 163      * See new().
 164      * @stable ICU 2.6
 165      */
 166     static inline void * U_EXPORT2 operator new(size_t, void *ptr) U_NO_THROW { return ptr; }
 167
 168     /**
 169      * Override for ICU4C C++ memory management for STL.
 170      * See delete().
 171      * @stable ICU 2.6
 172      */
 173     static inline void U_EXPORT2 operator delete(void *, void *) U_NO_THROW {}
 174 #endif /* U_HAVE_PLACEMENT_NEW */
 175 #if U_HAVE_DEBUG_LOCATION_NEW
 176     /**
 177       * This method overrides the MFC debug version of the operator new
 178       *
 179       * @param size   The requested memory size
 180       * @param file   The file where the allocation was requested
 181       * @param line   The line where the allocation was requested
 182       */
 183     static void * U_EXPORT2 operator new(size_t size, const char* file, int line) U_NO_THROW;
 184     /**
 185       * This method provides a matching delete for the MFC debug new
 186       *
 187       * @param p      The pointer to the allocated memory
 188       * @param file   The file where the allocation was requested
 189       * @param line   The line where the allocation was requested
 190       */
 191     static void U_EXPORT2 operator delete(void* p, const char* file, int line) U_NO_THROW;
 192 #endif /* U_HAVE_DEBUG_LOCATION_NEW */
 193 #endif /* U_OVERRIDE_CXX_ALLOCATION */
 194
 195     /*
 196      * Assignment operator not declared. The compiler will provide one
 197      * which does nothing since this class does not contain any data members.
 198      * API/code coverage may show the assignment operator as present and
 199      * untested - ignore.
 200      * Subclasses need this assignment operator if they use compiler-provided
 201      * assignment operators of their own. An alternative to not declaring one
 202      * here would be to declare and empty-implement a protected or public one.
 203     UMemory &UMemory::operator=(const UMemory &);
 204      */
 205 };
 206
 207 /**
 208  * UObject is the common ICU "boilerplate" class.
 209  * UObject inherits UMemory (starting with ICU 2.4),
 210  * and all other public ICU C++ classes
 211  * are derived from UObject (starting with ICU 2.2).
 212  *
 213  * UObject contains common virtual functions like for ICU's "poor man's RTTI".
 214  * It does not contain default implementations of virtual methods
 215  * like getDynamicClassID to allow derived classes such as Format
 216  * to declare these as pure virtual.
 217  *
 218  * The clone() function is not available in UObject because it is not
 219  * implemented by all ICU classes.
 220  * Many ICU services provide a clone() function for their class trees,
 221  * defined on the service's C++ base class, and all subclasses within that
 222  * service class tree return a pointer to the service base class
 223  * (which itself is a subclass of UObject).
 224  * This is because some compilers do not support covariant (same-as-this)
 225  * return types; cast to the appropriate subclass if necessary.
 226  *
 227  * @stable ICU 2.2
 228  */
 229 class U_COMMON_API UObject : public UMemory {
 230 public:
 231     /**
 232      * Destructor.
 233      *
 234      * @stable ICU 2.2
 235      */
 236     virtual ~UObject();
 237
 238     /**
 239      * ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.
 240      *
 241      * @stable ICU 2.2
 242      */
 243     virtual UClassID getDynamicClassID() const = 0;
 244
 245 protected:
 246     // the following functions are protected to prevent instantiation and
 247     // direct use of UObject itself
 248
 249     // default constructor
 250     // commented out because UObject is abstract (see getDynamicClassID)
 251     // inline UObject() {}
 252
 253     // copy constructor
 254     // commented out because UObject is abstract (see getDynamicClassID)
 255     // inline UObject(const UObject &other) {}
 256
 257 #if 0
 258     // TODO Sometime in the future. Implement operator==().
 259     // (This comment inserted in 2.2)
 260     // some or all of the following "boilerplate" functions may be made public
 261     // in a future ICU4C release when all subclasses implement them
 262
 263     // assignment operator
 264     // (not virtual, see "Taligent's Guide to Designing Programs" pp.73..74)
 265     // commented out because the implementation is the same as a compiler's default
 266     // UObject &operator=(const UObject &other) { return *this; }
 267
 268     // comparison operators
 269     virtual inline UBool operator==(const UObject &other) const { return this==&other; }
 270     inline UBool operator!=(const UObject &other) const { return !operator==(other); }
 271
 272     // clone() commented out from the base class:
 273     // some compilers do not support co-variant return types
 274     // (i.e., subclasses would have to return UObject * as well, instead of SubClass *)
 275     // see also UObject class documentation.
 276     // virtual UObject *clone() const;
 277 #endif
 278
 279     /*
 280      * Assignment operator not declared. The compiler will provide one
 281      * which does nothing since this class does not contain any data members.
 282      * API/code coverage may show the assignment operator as present and
 283      * untested - ignore.
 284      * Subclasses need this assignment operator if they use compiler-provided
 285      * assignment operators of their own. An alternative to not declaring one
 286      * here would be to declare and empty-implement a protected or public one.
 287     UObject &UObject::operator=(const UObject &);
 288      */
 289
 290 // Future implementation for RTTI that support subtyping. [alan]
 291 //
 292 //  public:
 293 //     /**
 294 //      * @internal
 295 //      */
 296 //     static UClassID getStaticClassID();
 297 //
 298 //     /**
 299 //      * @internal
 300 //      */
 301 //     UBool instanceOf(UClassID type) const;
 302 };
 303
 304 #ifndef U_HIDE_INTERNAL_API
 305 /**
 306  * This is a simple macro to add ICU RTTI to an ICU object implementation.
 307  * This does not go into the header. This should only be used in *.cpp files.
 308  *
 309  * @param myClass The name of the class that needs RTTI defined.
 310  * @internal
 311  */
 312 #define UOBJECT_DEFINE_RTTI_IMPLEMENTATION(myClass) \
 313     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 314         static char classID = 0; \
 315         return (UClassID)&classID; \
 316     } \
 317     UClassID myClass::getDynamicClassID() const \
 318     { return myClass::getStaticClassID(); }
 319
 320
 321 /**
 322  * This macro adds ICU RTTI to an ICU abstract class implementation.
 323  * This macro should be invoked in *.cpp files.  The corresponding
 324  * header should declare getStaticClassID.
 325  *
 326  * @param myClass The name of the class that needs RTTI defined.
 327  * @internal
 328  */
 329 #define UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(myClass) \
 330     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 331         static char classID = 0; \
 332         return (UClassID)&classID; \
 333     }
 334
 335 /**
 336  * This is a simple macro to express that a class and its subclasses do not offer
 337  * ICU's "poor man's RTTI".
 338  * Beginning with ICU 4.6, ICU requires C++ compiler RTTI.
 339  * This does not go into the header. This should only be used in *.cpp files.
 340  * Use this with a private getDynamicClassID() in an immediate subclass of UObject.
 341  *
 342  * @param myClass The name of the class that needs RTTI defined.
 343  * @internal
 344  */
 345 #define UOBJECT_DEFINE_NO_RTTI_IMPLEMENTATION(myClass) \
 346     UClassID myClass::getDynamicClassID() const { return NULL; }
 347
 348 // /**
 349 //  * This macro adds ICU RTTI to an ICU concrete class implementation.
 350 //  * This macro should be invoked in *.cpp files.  The corresponding
 351 //  * header should declare getDynamicClassID and getStaticClassID.
 352 //  *
 353 //  * @param myClass The name of the class that needs RTTI defined.
 354 //  * @param myParent The name of the myClass's parent.
 355 //  * @internal
 356 //  */
 357 /*#define UOBJECT_DEFINE_RTTI_IMPLEMENTATION(myClass, myParent) \
 358     UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(myClass, myParent) \
 359     UClassID myClass::getDynamicClassID() const { \
 360         return myClass::getStaticClassID(); \
 361     }
 362 */
 363 #endif  /* U_HIDE_INTERNAL_API */
 364
 365 U_NAMESPACE_END
 366
 367 #endif