icuSources/common/brkeng.h

   1 /**
   2  ************************************************************************************
   3  * Copyright (C) 2006-2012, International Business Machines Corporation and others. *
   4  * All Rights Reserved.                                                             *
   5  ************************************************************************************
   6  */
   7
   8 #ifndef BRKENG_H
   9 #define BRKENG_H
  10
  11 #include "unicode/utypes.h"
  12 #include "unicode/uobject.h"
  13 #include "unicode/utext.h"
  14 #include "unicode/uscript.h"
  15
  16 U_NAMESPACE_BEGIN
  17
  18 class UnicodeSet;
  19 class UStack;
  20 class DictionaryMatcher;
  21
  22 /*******************************************************************
  23  * LanguageBreakEngine
  24  */
  25
  26 /**
  27  * <p>LanguageBreakEngines implement language-specific knowledge for
  28  * finding text boundaries within a run of characters belonging to a
  29  * specific set. The boundaries will be of a specific kind, e.g. word,
  30  * line, etc.</p>
  31  *
  32  * <p>LanguageBreakEngines should normally be implemented so as to
  33  * be shared between threads without locking.</p>
  34  */
  35 class LanguageBreakEngine : public UMemory {
  36  public:
  37
  38   /**
  39    * <p>Default constructor.</p>
  40    *
  41    */
  42   LanguageBreakEngine();
  43
  44   /**
  45    * <p>Virtual destructor.</p>
  46    */
  47   virtual ~LanguageBreakEngine();
  48
  49  /**
  50   * <p>Indicate whether this engine handles a particular character for
  51   * a particular kind of break.</p>
  52   *
  53   * @param c A character which begins a run that the engine might handle
  54   * @param breakType The type of text break which the caller wants to determine
  55   * @return TRUE if this engine handles the particular character and break
  56   * type.
  57   */
  58   virtual UBool handles(UChar32 c, int32_t breakType) const = 0;
  59
  60  /**
  61   * <p>Find any breaks within a run in the supplied text.</p>
  62   *
  63   * @param text A UText representing the text. The
  64   * iterator is left at the end of the run of characters which the engine
  65   * is capable of handling.
  66   * @param startPos The start of the run within the supplied text.
  67   * @param endPos The end of the run within the supplied text.
  68   * @param reverse Whether the caller is looking for breaks in a reverse
  69   * direction.
  70   * @param breakType The type of break desired, or -1.
  71   * @param foundBreaks An allocated C array of the breaks found, if any
  72   * @return The number of breaks found.
  73   */
  74   virtual int32_t findBreaks( UText *text,
  75                               int32_t startPos,
  76                               int32_t endPos,
  77                               UBool reverse,
  78                               int32_t breakType,
  79                               UStack &foundBreaks ) const = 0;
  80
  81 };
  82
  83 /*******************************************************************
  84  * LanguageBreakFactory
  85  */
  86
  87 /**
  88  * <p>LanguageBreakFactorys find and return a LanguageBreakEngine
  89  * that can determine breaks for characters in a specific set, if
  90  * such an object can be found.</p>
  91  *
  92  * <p>If a LanguageBreakFactory is to be shared between threads,
  93  * appropriate synchronization must be used; there is none internal
  94  * to the factory.</p>
  95  *
  96  * <p>A LanguageBreakEngine returned by a LanguageBreakFactory can
  97  * normally be shared between threads without synchronization, unless
  98  * the specific subclass of LanguageBreakFactory indicates otherwise.</p>
  99  *
 100  * <p>A LanguageBreakFactory is responsible for deleting any LanguageBreakEngine
 101  * it returns when it itself is deleted, unless the specific subclass of
 102  * LanguageBreakFactory indicates otherwise. Naturally, the factory should
 103  * not be deleted until the LanguageBreakEngines it has returned are no
 104  * longer needed.</p>
 105  */
 106 class LanguageBreakFactory : public UMemory {
 107  public:
 108
 109   /**
 110    * <p>Default constructor.</p>
 111    *
 112    */
 113   LanguageBreakFactory();
 114
 115   /**
 116    * <p>Virtual destructor.</p>
 117    */
 118   virtual ~LanguageBreakFactory();
 119
 120  /**
 121   * <p>Find and return a LanguageBreakEngine that can find the desired
 122   * kind of break for the set of characters to which the supplied
 123   * character belongs. It is up to the set of available engines to
 124   * determine what the sets of characters are.</p>
 125   *
 126   * @param c A character that begins a run for which a LanguageBreakEngine is
 127   * sought.
 128   * @param breakType The kind of text break for which a LanguageBreakEngine is
 129   * sought.
 130   * @return A LanguageBreakEngine with the desired characteristics, or 0.
 131   */
 132   virtual const LanguageBreakEngine *getEngineFor(UChar32 c, int32_t breakType) = 0;
 133
 134 };
 135
 136 /*******************************************************************
 137  * UnhandledEngine
 138  */
 139
 140 /**
 141  * <p>UnhandledEngine is a special subclass of LanguageBreakEngine that
 142  * handles characters that no other LanguageBreakEngine is available to
 143  * handle. It is told the character and the type of break; at its
 144  * discretion it may handle more than the specified character (e.g.,
 145  * the entire script to which that character belongs.</p>
 146  *
 147  * <p>UnhandledEngines may not be shared between threads without
 148  * external synchronization.</p>
 149  */
 150
 151 class UnhandledEngine : public LanguageBreakEngine {
 152  private:
 153
 154     /**
 155      * The sets of characters handled, for each break type
 156      * @internal
 157      */
 158
 159   UnicodeSet    *fHandled[4];
 160
 161  public:
 162
 163   /**
 164    * <p>Default constructor.</p>
 165    *
 166    */
 167   UnhandledEngine(UErrorCode &status);
 168
 169   /**
 170    * <p>Virtual destructor.</p>
 171    */
 172   virtual ~UnhandledEngine();
 173
 174  /**
 175   * <p>Indicate whether this engine handles a particular character for
 176   * a particular kind of break.</p>
 177   *
 178   * @param c A character which begins a run that the engine might handle
 179   * @param breakType The type of text break which the caller wants to determine
 180   * @return TRUE if this engine handles the particular character and break
 181   * type.
 182   */
 183   virtual UBool handles(UChar32 c, int32_t breakType) const;
 184
 185  /**
 186   * <p>Find any breaks within a run in the supplied text.</p>
 187   *
 188   * @param text A UText representing the text (TODO: UText). The
 189   * iterator is left at the end of the run of characters which the engine
 190   * is capable of handling.
 191   * @param startPos The start of the run within the supplied text.
 192   * @param endPos The end of the run within the supplied text.
 193   * @param reverse Whether the caller is looking for breaks in a reverse
 194   * direction.
 195   * @param breakType The type of break desired, or -1.
 196   * @param foundBreaks An allocated C array of the breaks found, if any
 197   * @return The number of breaks found.
 198   */
 199   virtual int32_t findBreaks( UText *text,
 200                               int32_t startPos,
 201                               int32_t endPos,
 202                               UBool reverse,
 203                               int32_t breakType,
 204                               UStack &foundBreaks ) const;
 205
 206  /**
 207   * <p>Tell the engine to handle a particular character and break type.</p>
 208   *
 209   * @param c A character which the engine should handle
 210   * @param breakType The type of text break for which the engine should handle c
 211   */
 212   virtual void handleCharacter(UChar32 c, int32_t breakType);
 213
 214 };
 215
 216 /*******************************************************************
 217  * ICULanguageBreakFactory
 218  */
 219
 220 /**
 221  * <p>ICULanguageBreakFactory is the default LanguageBreakFactory for
 222  * ICU. It creates dictionary-based LanguageBreakEngines from dictionary
 223  * data in the ICU data file.</p>
 224  */
 225 class ICULanguageBreakFactory : public LanguageBreakFactory {
 226  private:
 227
 228     /**
 229      * The stack of break engines created by this factory
 230      * @internal
 231      */
 232
 233   UStack    *fEngines;
 234
 235  public:
 236
 237   /**
 238    * <p>Standard constructor.</p>
 239    *
 240    */
 241   ICULanguageBreakFactory(UErrorCode &status);
 242
 243   /**
 244    * <p>Virtual destructor.</p>
 245    */
 246   virtual ~ICULanguageBreakFactory();
 247
 248  /**
 249   * <p>Find and return a LanguageBreakEngine that can find the desired
 250   * kind of break for the set of characters to which the supplied
 251   * character belongs. It is up to the set of available engines to
 252   * determine what the sets of characters are.</p>
 253   *
 254   * @param c A character that begins a run for which a LanguageBreakEngine is
 255   * sought.
 256   * @param breakType The kind of text break for which a LanguageBreakEngine is
 257   * sought.
 258   * @return A LanguageBreakEngine with the desired characteristics, or 0.
 259   */
 260   virtual const LanguageBreakEngine *getEngineFor(UChar32 c, int32_t breakType);
 261
 262 protected:
 263  /**
 264   * <p>Create a LanguageBreakEngine for the set of characters to which
 265   * the supplied character belongs, for the specified break type.</p>
 266   *
 267   * @param c A character that begins a run for which a LanguageBreakEngine is
 268   * sought.
 269   * @param breakType The kind of text break for which a LanguageBreakEngine is
 270   * sought.
 271   * @return A LanguageBreakEngine with the desired characteristics, or 0.
 272   */
 273   virtual const LanguageBreakEngine *loadEngineFor(UChar32 c, int32_t breakType);
 274
 275   /**
 276    * <p>Create a DictionaryMatcher for the specified script and break type.</p>
 277    * @param script An ISO 15924 script code that identifies the dictionary to be
 278    * created.
 279    * @param breakType The kind of text break for which a dictionary is
 280    * sought.
 281    * @return A DictionaryMatcher with the desired characteristics, or NULL.
 282    */
 283   virtual DictionaryMatcher *loadDictionaryMatcherFor(UScriptCode script, int32_t breakType);
 284 };
 285
 286 U_NAMESPACE_END
 287
 288     /* BRKENG_H */
 289 #endif