| /* |
| ********************************************************************** |
| * Copyright (C) 1999-2004 IBM Corp. All rights reserved. |
| ********************************************************************** |
| * Date Name Description |
| * 12/1/99 rgillam Complete port from Java. |
| * 01/13/2000 helena Added UErrorCode to ctors. |
| ********************************************************************** |
| */ |
| |
| #ifndef DBBI_H |
| #define DBBI_H |
| |
| #include "unicode/rbbi.h" |
| |
| #if !UCONFIG_NO_BREAK_ITERATION |
| |
| U_NAMESPACE_BEGIN |
| |
| /* forward declaration */ |
| class DictionaryBasedBreakIteratorTables; |
| |
| /** |
| * A subclass of RuleBasedBreakIterator that adds the ability to use a dictionary |
| * to further subdivide ranges of text beyond what is possible using just the |
| * state-table-based algorithm. This is necessary, for example, to handle |
| * word and line breaking in Thai, which doesn't use spaces between words. The |
| * state-table-based algorithm used by RuleBasedBreakIterator is used to divide |
| * up text as far as possible, and then contiguous ranges of letters are |
| * repeatedly compared against a list of known words (i.e., the dictionary) |
| * to divide them up into words. |
| * |
| * <p>Applications do not normally need to include this header.</p> |
| * |
| * <p>This class will probably be deprecated in a future release of ICU, and replaced |
| * with a more flexible and capable dictionary based break iterator. This change |
| * should be invisible to applications, because creation and use of instances of |
| * DictionaryBasedBreakIterator is through the factories and abstract |
| * API on class BreakIterator, which will remain stable.</p> |
| * |
| * <p>This class is not intended to be subclassed.</p> |
| * |
| * |
| * DictionaryBasedBreakIterator uses the same rule language as RuleBasedBreakIterator, |
| * but adds one more special substitution name: <dictionary>. This substitution |
| * name is used to identify characters in words in the dictionary. The idea is that |
| * if the iterator passes over a chunk of text that includes two or more characters |
| * in a row that are included in <dictionary>, it goes back through that range and |
| * derives additional break positions (if possible) using the dictionary. |
| * |
| * DictionaryBasedBreakIterator is also constructed with the filename of a dictionary |
| * file. It follows a prescribed search path to locate the dictionary (right now, |
| * it looks for it in /com/ibm/text/resources in each directory in the classpath, |
| * and won't find it in JAR files, but this location is likely to change). The |
| * dictionary file is in a serialized binary format. We have a very primitive (and |
| * slow) BuildDictionaryFile utility for creating dictionary files, but aren't |
| * currently making it public. Contact us for help. |
| * <p> |
| * <b> NOTE </b> The DictionaryBasedIterator class is still under development. The |
| * APIs are not in stable condition yet. |
| */ |
| class U_COMMON_API DictionaryBasedBreakIterator : public RuleBasedBreakIterator { |
| |
| private: |
| |
| /** |
| * when a range of characters is divided up using the dictionary, the break |
| * positions that are discovered are stored here, preventing us from having |
| * to use either the dictionary or the state table again until the iterator |
| * leaves this range of text |
| */ |
| int32_t* cachedBreakPositions; |
| |
| /** |
| * The number of elements in cachedBreakPositions |
| */ |
| int32_t numCachedBreakPositions; |
| |
| /** |
| * if cachedBreakPositions is not null, this indicates which item in the |
| * cache the current iteration position refers to |
| */ |
| int32_t positionInCache; |
| |
| DictionaryBasedBreakIteratorTables *fTables; |
| |
| /**======================================================================= |
| * Create a dictionary based break boundary detection iterator. |
| * @param tablesImage The location for the dictionary to be loaded into memory |
| * @param dictionaryFilename The name of the dictionary file |
| * @param status the error code status |
| * @return A dictionary based break detection iterator. The UErrorCode& status |
| * parameter is used to return status information to the user. |
| * To check whether the construction succeeded or not, you should check |
| * the value of U_SUCCESS(err). If you wish more detailed information, you |
| * can check for informational error results which still indicate success. For example, |
| * U_FILE_ACCESS_ERROR will be returned if the file does not exist. |
| * The caller owns the returned object and is responsible for deleting it. |
| ======================================================================= */ |
| DictionaryBasedBreakIterator(UDataMemory* tablesImage, const char* dictionaryFilename, UErrorCode& status); |
| |
| public: |
| //======================================================================= |
| // boilerplate |
| //======================================================================= |
| |
| /** |
| * Destructor |
| * @stable ICU 2.0 |
| */ |
| virtual ~DictionaryBasedBreakIterator(); |
| |
| /** |
| * Default constructor. Creates an "empty" break iterator. |
| * Such an iterator can subsequently be assigned to. |
| * @return the newly created DictionaryBaseBreakIterator. |
| * @stable ICU 2.0 |
| */ |
| DictionaryBasedBreakIterator(); |
| |
| /** |
| * Copy constructor. |
| * @param other The DictionaryBasedBreakIterator to be copied. |
| * @return the newly created DictionaryBasedBreakIterator. |
| * @stable ICU 2.0 |
| */ |
| DictionaryBasedBreakIterator(const DictionaryBasedBreakIterator &other); |
| |
| /** |
| * Assignment operator. |
| * @param that The object to be copied. |
| * @return the newly set DictionaryBasedBreakIterator. |
| * @stable ICU 2.0 |
| */ |
| DictionaryBasedBreakIterator& operator=(const DictionaryBasedBreakIterator& that); |
| |
| /** |
| * Returns a newly-constructed RuleBasedBreakIterator with the same |
| * behavior, and iterating over the same text, as this one. |
| * @return Returns a newly-constructed RuleBasedBreakIterator. |
| * @stable ICU 2.0 |
| */ |
| virtual BreakIterator* clone(void) const; |
| |
| //======================================================================= |
| // BreakIterator overrides |
| //======================================================================= |
| /** |
| * Advances the iterator backwards, to the last boundary preceding this one. |
| * @return The position of the last boundary position preceding this one. |
| * @stable ICU 2.0 |
| */ |
| virtual int32_t previous(void); |
| |
| /** |
| * Sets the iterator to refer to the first boundary position following |
| * the specified position. |
| * @param offset The position from which to begin searching for a break position. |
| * @return The position of the first break after the current position. |
| * @stable ICU 2.0 |
| */ |
| virtual int32_t following(int32_t offset); |
| |
| /** |
| * Sets the iterator to refer to the last boundary position before the |
| * specified position. |
| * @param offset The position to begin searching for a break from. |
| * @return The position of the last boundary before the starting position. |
| * @stable ICU 2.0 |
| */ |
| virtual int32_t preceding(int32_t offset); |
| |
| /** |
| * Returns the class ID for this class. This is useful only for |
| * comparing to a return value from getDynamicClassID(). For example: |
| * |
| * Base* polymorphic_pointer = createPolymorphicObject(); |
| * if (polymorphic_pointer->getDynamicClassID() == |
| * Derived::getStaticClassID()) ... |
| * |
| * @return The class ID for all objects of this class. |
| * @stable ICU 2.0 |
| */ |
| static UClassID getStaticClassID(void); |
| |
| /** |
| * Returns a unique class ID POLYMORPHICALLY. Pure virtual override. |
| * This method is to implement a simple version of RTTI, since not all |
| * C++ compilers support genuine RTTI. Polymorphic operator==() and |
| * clone() methods call this method. |
| * |
| * @return The class ID for this object. All objects of a |
| * given class have the same class ID. Objects of |
| * other classes have different class IDs. |
| * @stable ICU 2.0 |
| */ |
| virtual UClassID getDynamicClassID(void) const; |
| |
| protected: |
| //======================================================================= |
| // implementation |
| //======================================================================= |
| /** |
| * This method is the actual implementation of the next() method. All iteration |
| * vectors through here. This method initializes the state machine to state 1 |
| * and advances through the text character by character until we reach the end |
| * of the text or the state machine transitions to state 0. We update our return |
| * value every time the state machine passes through a possible end state. |
| * @internal |
| */ |
| virtual int32_t handleNext(void); |
| |
| /** |
| * removes the cache of break positions (usually in response to a change in |
| * position of some sort) |
| * @internal |
| */ |
| virtual void reset(void); |
| |
| /** |
| * init Initialize a dbbi. Common routine for use by constructors. |
| * @internal |
| */ |
| void init(); |
| |
| /** |
| * @param stackBuffer user allocated space for the new clone. If NULL new memory will be allocated. |
| * If buffer is not large enough, new memory will be allocated. |
| * @param BufferSize reference to size of allocated space. |
| * If BufferSize == 0, a sufficient size for use in cloning will |
| * be returned ('pre-flighting') |
| * If BufferSize is not enough for a stack-based safe clone, |
| * new memory will be allocated. |
| * @param status to indicate whether the operation went on smoothly or there were errors |
| * An informational status value, U_SAFECLONE_ALLOCATED_ERROR, is used if any allocations were |
| * necessary. |
| * @return pointer to the new clone |
| * @internal |
| */ |
| virtual BreakIterator * createBufferClone(void *stackBuffer, |
| int32_t &BufferSize, |
| UErrorCode &status); |
| |
| |
| private: |
| /** |
| * This is the function that actually implements the dictionary-based |
| * algorithm. Given the endpoints of a range of text, it uses the |
| * dictionary to determine the positions of any boundaries in this |
| * range. It stores all the boundary positions it discovers in |
| * cachedBreakPositions so that we only have to do this work once |
| * for each time we enter the range. |
| * @param startPos The start position of a range of text |
| * @param endPos The end position of a range of text |
| * @param status The error code status |
| */ |
| void divideUpDictionaryRange(int32_t startPos, int32_t endPos, UErrorCode &status); |
| |
| |
| /* |
| * HSYS : Please revisit with Rich, the ctors of the DBBI class is currently |
| * marked as private. |
| */ |
| friend class DictionaryBasedBreakIteratorTables; |
| friend class BreakIterator; |
| }; |
| |
| U_NAMESPACE_END |
| |
| #endif /* #if !UCONFIG_NO_BREAK_ITERATION */ |
| |
| #endif |
