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 #include "unicode/platform.h"
  24
  25 /**
  26  * \file
  27  * \brief C++ API: Common ICU base class UObject.
  28  */
  29
  30 /**
  31  * \def U_NO_THROW
  32  *         Since ICU 64, use U_NOEXCEPT instead.
  33  *
  34  *         Previously, define this to define the throw() specification so
  35  *                 certain functions do not throw any exceptions
  36  *
  37  *         UMemory operator new methods should have the throw() specification
  38  *         appended to them, so that the compiler adds the additional NULL check
  39  *         before calling constructors. Without, if <code>operator new</code> returns NULL the
  40  *         constructor is still called, and if the constructor references member
  41  *         data, (which it typically does), the result is a segmentation violation.
  42  *
  43  * @stable ICU 4.2. Since ICU 64, Use U_NOEXCEPT instead. See ICU-20422.
  44  */
  45 #ifndef U_NO_THROW
  46 #define U_NO_THROW throw()
  47 #endif
  48
  49 /*===========================================================================*/
  50 /* UClassID-based RTTI */
  51 /*===========================================================================*/
  52
  53 /**
  54  * UClassID is used to identify classes without using the compiler's RTTI.
  55  * This was used before C++ compilers consistently supported RTTI.
  56  * ICU 4.6 requires compiler RTTI to be turned on.
  57  *
  58  * Each class hierarchy which needs
  59  * to implement polymorphic clone() or operator==() defines two methods,
  60  * described in detail below.  UClassID values can be compared using
  61  * operator==(). Nothing else should be done with them.
  62  *
  63  * \par
  64  * In class hierarchies that implement "poor man's RTTI",
  65  * each concrete subclass implements getDynamicClassID() in the same way:
  66  *
  67  * \code
  68  *      class Derived {
  69  *      public:
  70  *          virtual UClassID getDynamicClassID() const
  71  *            { return Derived::getStaticClassID(); }
  72  *      }
  73  * \endcode
  74  *
  75  * Each concrete class implements getStaticClassID() as well, which allows
  76  * clients to test for a specific type.
  77  *
  78  * \code
  79  *      class Derived {
  80  *      public:
  81  *          static UClassID U_EXPORT2 getStaticClassID();
  82  *      private:
  83  *          static char fgClassID;
  84  *      }
  85  *
  86  *      // In Derived.cpp:
  87  *      UClassID Derived::getStaticClassID()
  88  *        { return (UClassID)&Derived::fgClassID; }
  89  *      char Derived::fgClassID = 0; // Value is irrelevant
  90  * \endcode
  91  * @stable ICU 2.0
  92  */
  93 typedef void* UClassID;
  94
  95 #if U_SHOW_CPLUSPLUS_API
  96 U_NAMESPACE_BEGIN
  97
  98 /**
  99  * UMemory is the common ICU base class.
 100  * All other ICU C++ classes are derived from UMemory (starting with ICU 2.4).
 101  *
 102  * This is primarily to make it possible and simple to override the
 103  * C++ memory management by adding new/delete operators to this base class.
 104  *
 105  * To override ALL ICU memory management, including that from plain C code,
 106  * replace the allocation functions declared in cmemory.h
 107  *
 108  * UMemory does not contain any virtual functions.
 109  * Common "boilerplate" functions are defined in UObject.
 110  *
 111  * @stable ICU 2.4
 112  */
 113 class U_COMMON_API UMemory {
 114 public:
 115
 116 /* test versions for debugging shaper heap memory problems */
 117 #ifdef SHAPER_MEMORY_DEBUG
 118     static void * NewArray(int size, int count);
 119     static void * GrowArray(void * array, int newSize );
 120     static void   FreeArray(void * array );
 121 #endif
 122
 123 #if U_OVERRIDE_CXX_ALLOCATION
 124     /**
 125      * Override for ICU4C C++ memory management.
 126      * simple, non-class types are allocated using the macros in common/cmemory.h
 127      * (uprv_malloc(), uprv_free(), uprv_realloc());
 128      * they or something else could be used here to implement C++ new/delete
 129      * for ICU4C C++ classes
 130      * @stable ICU 2.4
 131      */
 132     static void * U_EXPORT2 operator new(size_t size) U_NOEXCEPT;
 133
 134     /**
 135      * Override for ICU4C C++ memory management.
 136      * See new().
 137      * @stable ICU 2.4
 138      */
 139     static void * U_EXPORT2 operator new[](size_t size) U_NOEXCEPT;
 140
 141     /**
 142      * Override for ICU4C C++ memory management.
 143      * simple, non-class types are allocated using the macros in common/cmemory.h
 144      * (uprv_malloc(), uprv_free(), uprv_realloc());
 145      * they or something else could be used here to implement C++ new/delete
 146      * for ICU4C C++ classes
 147      * @stable ICU 2.4
 148      */
 149     static void U_EXPORT2 operator delete(void *p) U_NOEXCEPT;
 150
 151     /**
 152      * Override for ICU4C C++ memory management.
 153      * See delete().
 154      * @stable ICU 2.4
 155      */
 156     static void U_EXPORT2 operator delete[](void *p) U_NOEXCEPT;
 157
 158 #if U_HAVE_PLACEMENT_NEW
 159     /**
 160      * Override for ICU4C C++ memory management for STL.
 161      * See new().
 162      * @stable ICU 2.6
 163      */
 164     static inline void * U_EXPORT2 operator new(size_t, void *ptr) U_NOEXCEPT { return ptr; }
 165
 166     /**
 167      * Override for ICU4C C++ memory management for STL.
 168      * See delete().
 169      * @stable ICU 2.6
 170      */
 171     static inline void U_EXPORT2 operator delete(void *, void *) U_NOEXCEPT {}
 172 #endif /* U_HAVE_PLACEMENT_NEW */
 173 #if U_HAVE_DEBUG_LOCATION_NEW
 174     /**
 175       * This method overrides the MFC debug version of the operator new
 176       *
 177       * @param size   The requested memory size
 178       * @param file   The file where the allocation was requested
 179       * @param line   The line where the allocation was requested
 180       */
 181     static void * U_EXPORT2 operator new(size_t size, const char* file, int line) U_NOEXCEPT;
 182     /**
 183       * This method provides a matching delete for the MFC debug new
 184       *
 185       * @param p      The pointer to the allocated memory
 186       * @param file   The file where the allocation was requested
 187       * @param line   The line where the allocation was requested
 188       */
 189     static void U_EXPORT2 operator delete(void* p, const char* file, int line) U_NOEXCEPT;
 190 #endif /* U_HAVE_DEBUG_LOCATION_NEW */
 191 #endif /* U_OVERRIDE_CXX_ALLOCATION */
 192
 193     /*
 194      * Assignment operator not declared. The compiler will provide one
 195      * which does nothing since this class does not contain any data members.
 196      * API/code coverage may show the assignment operator as present and
 197      * untested - ignore.
 198      * Subclasses need this assignment operator if they use compiler-provided
 199      * assignment operators of their own. An alternative to not declaring one
 200      * here would be to declare and empty-implement a protected or public one.
 201     UMemory &UMemory::operator=(const UMemory &);
 202      */
 203 };
 204
 205 /**
 206  * UObject is the common ICU "boilerplate" class.
 207  * UObject inherits UMemory (starting with ICU 2.4),
 208  * and all other public ICU C++ classes
 209  * are derived from UObject (starting with ICU 2.2).
 210  *
 211  * UObject contains common virtual functions, in particular a virtual destructor.
 212  *
 213  * The clone() function is not available in UObject because it is not
 214  * implemented by all ICU classes.
 215  * Many ICU services provide a clone() function for their class trees,
 216  * defined on the service's C++ base class, and all subclasses within that
 217  * service class tree return a pointer to the service base class
 218  * (which itself is a subclass of UObject).
 219  * This is because some compilers do not support covariant (same-as-this)
 220  * return types; cast to the appropriate subclass if necessary.
 221  *
 222  * @stable ICU 2.2
 223  */
 224 class U_COMMON_API UObject : public UMemory {
 225 public:
 226     /**
 227      * Destructor.
 228      *
 229      * @stable ICU 2.2
 230      */
 231     virtual ~UObject();
 232
 233     /**
 234      * ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.
 235      * The base class implementation returns a dummy value.
 236      *
 237      * Use compiler RTTI rather than ICU's "poor man's RTTI".
 238      * Since ICU 4.6, new ICU C++ class hierarchies do not implement "poor man's RTTI".
 239      *
 240      * @stable ICU 2.2
 241      */
 242     virtual UClassID getDynamicClassID() const;
 243
 244 protected:
 245     // the following functions are protected to prevent instantiation and
 246     // direct use of UObject itself
 247
 248     // default constructor
 249     // inline UObject() {}
 250
 251     // copy constructor
 252     // inline UObject(const UObject &other) {}
 253
 254 #if 0
 255     // TODO Sometime in the future. Implement operator==().
 256     // (This comment inserted in 2.2)
 257     // some or all of the following "boilerplate" functions may be made public
 258     // in a future ICU4C release when all subclasses implement them
 259
 260     // assignment operator
 261     // (not virtual, see "Taligent's Guide to Designing Programs" pp.73..74)
 262     // commented out because the implementation is the same as a compiler's default
 263     // UObject &operator=(const UObject &other) { return *this; }
 264
 265     // comparison operators
 266     virtual inline UBool operator==(const UObject &other) const { return this==&other; }
 267     inline UBool operator!=(const UObject &other) const { return !operator==(other); }
 268
 269     // clone() commented out from the base class:
 270     // some compilers do not support co-variant return types
 271     // (i.e., subclasses would have to return UObject * as well, instead of SubClass *)
 272     // see also UObject class documentation.
 273     // virtual UObject *clone() const;
 274 #endif
 275
 276     /*
 277      * Assignment operator not declared. The compiler will provide one
 278      * which does nothing since this class does not contain any data members.
 279      * API/code coverage may show the assignment operator as present and
 280      * untested - ignore.
 281      * Subclasses need this assignment operator if they use compiler-provided
 282      * assignment operators of their own. An alternative to not declaring one
 283      * here would be to declare and empty-implement a protected or public one.
 284     UObject &UObject::operator=(const UObject &);
 285      */
 286 };
 287
 288 #ifndef U_HIDE_INTERNAL_API
 289 /**
 290  * This is a simple macro to add ICU RTTI to an ICU object implementation.
 291  * This does not go into the header. This should only be used in *.cpp files.
 292  *
 293  * @param myClass The name of the class that needs RTTI defined.
 294  * @internal
 295  */
 296 #define UOBJECT_DEFINE_RTTI_IMPLEMENTATION(myClass) \
 297     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 298         static char classID = 0; \
 299         return (UClassID)&classID; \
 300     } \
 301     UClassID myClass::getDynamicClassID() const \
 302     { return myClass::getStaticClassID(); }
 303
 304
 305 /**
 306  * This macro adds ICU RTTI to an ICU abstract class implementation.
 307  * This macro should be invoked in *.cpp files.  The corresponding
 308  * header should declare getStaticClassID.
 309  *
 310  * @param myClass The name of the class that needs RTTI defined.
 311  * @internal
 312  */
 313 #define UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(myClass) \
 314     UClassID U_EXPORT2 myClass::getStaticClassID() { \
 315         static char classID = 0; \
 316         return (UClassID)&classID; \
 317     }
 318
 319 #endif  /* U_HIDE_INTERNAL_API */
 320
 321 U_NAMESPACE_END
 322 #endif // U_SHOW_CPLUSPLUS_API
 323
 324 #endif