icuSources/common/unicode/uobject.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 ******************************************************************************
   5 *
   6 *   Copyright (C) 2002-2012, International Business Machines
   7 *   Corporation and others.  All Rights Reserved.
   8 *
   9 ******************************************************************************
  10 *   file name:  uobject.h
  11 *   encoding:   UTF-8
  12 *   tab size:   8 (not used)
  13 *   indentation:4
  14 *
  15 *   created on: 2002jun26
  16 *   created by: Markus W. Scherer
  17 */
  18
  19 #ifndef __UOBJECT_H__
  20 #define __UOBJECT_H__
  21
  22 #include "unicode/utypes.h"
  23
  24 #if U_SHOW_CPLUSPLUS_API
  25
  26 #include "unicode/platform.h"
  27
  28 /**
  29  * \file
  30  * \brief C++ API: Common ICU base class UObject.
  31  */
  32
  33 /**
  34  * \def U_NO_THROW
  35  *         Since ICU 64, use U_NOEXCEPT instead.
  36  *
  37  *         Previously, define this to define the throw() specification so
  38  *                 certain functions do not throw any exceptions
  39  *
  40  *         UMemory operator new methods should have the throw() specification
  41  *         appended to them, so that the compiler adds the additional NULL check
  42  *         before calling constructors. Without, if <code>operator new</code> returns NULL the
  43  *         constructor is still called, and if the constructor references member
  44  *         data, (which it typically does), the result is a segmentation violation.
  45  *
  46  * @stable ICU 4.2. Since ICU 64, Use U_NOEXCEPT instead. See ICU-20422.
  47  */
  48 #ifndef U_NO_THROW
  49 #define U_NO_THROW U_NOEXCEPT
  50 #endif
  51
  52 /*===========================================================================*/
  53 /* UClassID-based RTTI */
  54 /*===========================================================================*/
  55
  56 /**
  57  * UClassID is used to identify classes without using the compiler's RTTI.
  58  * This was used before C++ compilers consistently supported RTTI.
  59  * ICU 4.6 requires compiler RTTI to be turned on.
  60  *
  61  * Each class hierarchy which needs
  62  * to implement polymorphic clone() or operator==() defines two methods,
  63  * described in detail below.  UClassID values can be compared using
  64  * operator==(). Nothing else should be done with them.
  65  *
  66  * \par
  67  * In class hierarchies that implement "poor man's RTTI",
  68  * each concrete subclass implements getDynamicClassID() in the same way:
  69  *
  70  * \code
  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_NOEXCEPT;
 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_NOEXCEPT;
 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_NOEXCEPT;
 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_NOEXCEPT;
 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_NOEXCEPT { 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_NOEXCEPT {}
 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_NOEXCEPT;
 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_NOEXCEPT;
 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, in particular a virtual destructor.
 214  *
 215  * The clone() function is not available in UObject because it is not
 216  * implemented by all ICU classes.
 217  * Many ICU services provide a clone() function for their class trees,
 218  * defined on the service's C++ base class
 219  * (which itself is a subclass of UObject).
 220  *
 221  * @stable ICU 2.2
 222  */
 223 class U_COMMON_API UObject : public UMemory {
 224 public:
 225     /**
 226      * Destructor.
 227      *
 228      * @stable ICU 2.2
 229      */
 230     virtual ~UObject();
 231
 232     /**
 233      * ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.
 234      * The base class implementation returns a dummy value.
 235      *
 236      * Use compiler RTTI rather than ICU's "poor man's RTTI".
 237      * Since ICU 4.6, new ICU C++ class hierarchies do not implement "poor man's RTTI".
 238      *
 239      * @stable ICU 2.2
 240      */
 241     virtual UClassID getDynamicClassID() const;
 242
 243 protected:
 244     // the following functions are protected to prevent instantiation and
 245     // direct use of UObject itself
 246
 247     // default constructor
 248     // inline UObject() {}
 249
 250     // copy constructor
 251     // inline UObject(const UObject &other) {}
 252
 253 #if 0
 254     // TODO Sometime in the future. Implement operator==().
 255     // (This comment inserted in 2.2)
 256     // some or all of the following "boilerplate" functions may be made public
 257     // in a future ICU4C release when all subclasses implement them
 258
 259     // assignment operator
 260     // (not virtual, see "Taligent's Guide to Designing Programs" pp.73..74)
 261     // commented out because the implementation is the same as a compiler's default
 262     // UObject &operator=(const UObject &other) { return *this; }
 263
 264     // comparison operators
 265     virtual inline UBool operator==(const UObject &other) const { return this==&other; }
 266     inline UBool operator!=(const UObject &other) const { return !operator==(other); }
 267
 268     // clone() commented out from the base class:
 269     // some compilers do not support co-variant return types
 270     // (i.e., subclasses would have to return UObject * as well, instead of SubClass *)
 271     // see also UObject class documentation.
 272     // virtual UObject *clone() const;
 273 #endif
 274
 275     /*
 276      * Assignment operator not declared. The compiler will provide one
 277      * which does nothing since this class does not contain any data members.
 278      * API/code coverage may show the assignment operator as present and
 279      * untested - ignore.
 280      * Subclasses need this assignment operator if they use compiler-provided
 281      * assignment operators of their own. An alternative to not declaring one
 282      * here would be to declare and empty-implement a protected or public one.
 283     UObject &UObject::operator=(const UObject &);
 284      */
 285 };
 286
 287 #ifndef U_HIDE_INTERNAL_API
 288 /**
 289  * This is a simple macro to add ICU RTTI to an ICU object implementation.
 290  * This does not go into the header. This should only be used in *.cpp files.
 291  *
 292  * @param myClass The name of the class that needs RTTI defined.
 293  * @internal
 294  */
 295 #define UOBJECT_DEFINE_RTTI_IMPLEMENTATION(myClass) \
 296     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 297         static char classID = 0; \
 298         return (UClassID)&classID; \
 299     } \
 300     UClassID myClass::getDynamicClassID() const \
 301     { return myClass::getStaticClassID(); }
 302
 303
 304 /**
 305  * This macro adds ICU RTTI to an ICU abstract class implementation.
 306  * This macro should be invoked in *.cpp files.  The corresponding
 307  * header should declare getStaticClassID.
 308  *
 309  * @param myClass The name of the class that needs RTTI defined.
 310  * @internal
 311  */
 312 #define UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(myClass) \
 313     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 314         static char classID = 0; \
 315         return (UClassID)&classID; \
 316     }
 317
 318 #endif  /* U_HIDE_INTERNAL_API */
 319
 320 U_NAMESPACE_END
 321
 322 #endif /* U_SHOW_CPLUSPLUS_API */
 323
 324 #endif