/*

***************************************************************************

*   Copyright (C) 1999-2005 International Business Machines Corporation   *

*   and others. All rights reserved.                                      *

***************************************************************************

**********************************************************************

*   Date        Name        Description

*   10/22/99    alan        Creation.

*   11/11/99    rgillam     Complete port from Java.

**********************************************************************

*/

#ifndef RBBI_H

#define RBBI_H

#include "unicode/utypes.h"

/**

 * \file

 * \brief C++ API: Rule Based Break Iterator

 */

#if !UCONFIG_NO_BREAK_ITERATION

#include "unicode/brkiter.h"

#include "unicode/udata.h"

#include "unicode/parseerr.h"

struct UTrie;

U_NAMESPACE_BEGIN

/** @internal */

struct RBBIDataHeader;

class  RuleBasedBreakIteratorTables;

class  BreakIterator;

class  RBBIDataWrapper;

struct RBBIStateTable;

/**

 *

 * A subclass of BreakIterator whose behavior is specified using a list of rules.

 * <p>Instances of this class are most commonly created by the factory methods of

 *  BreakIterator::createWordInstance(), BreakIterator::createLineInstance(), etc.,

 *  and then used via the abstract API in class BreakIterator</p>

 *

 * <p>See the ICU User Guide for information on Break Iterator Rules.</p>

 *

 * <p>This class is not intended to be subclassed.  (Class DictionaryBasedBreakIterator

 *    is a subclass, but that relationship is effectively internal to the ICU

 *    implementation.  The subclassing interface to RulesBasedBreakIterator is

 *    not part of the ICU API, and may not remain stable.</p>

 *

 */

class U_COMMON_API RuleBasedBreakIterator : public BreakIterator {

protected:

    /**

     * The character iterator through which this BreakIterator accesses the text

     * @internal

     */

    CharacterIterator*  fText;

    /**

     * The rule data for this BreakIterator instance

     * @internal

     */

    RBBIDataWrapper    *fData;

    /** Index of the Rule {tag} values for the most recent match.

     *  @internal

    */

    int32_t             fLastRuleStatusIndex;

    /**

     * Rule tag value valid flag.

     * Some iterator operations don't intrinsically set the correct tag value.

     * This flag lets us lazily compute the value if we are ever asked for it.

     * @internal

     */

    UBool               fLastStatusIndexValid;

    /**

     * Counter for the number of characters encountered with the "dictionary"

     *   flag set.  Normal RBBI iterators don't use it, although the code

     *   for updating it is live.  Dictionary Based break iterators (a subclass

     *   of us) access this field directly.

     * @internal

     */

    uint32_t           fDictionaryCharCount;

    /**

     * Debugging flag.  Trace operation of state machine when true.

     * @internal

     */

    static UBool        fTrace;

protected:

    //=======================================================================

    // constructors

    //=======================================================================

    /**

     * Constructor from a flattened set of RBBI data in malloced memory.

     *             RulesBasedBreakIterators built from a custom set of rules

     *             are created via this constructor; the rules are compiled

     *             into memory, then the break iterator is constructed here.

     *

     *             The break iterator adopts the memory, and will

     *             free it when done.

     * @internal

     */

    RuleBasedBreakIterator(RBBIDataHeader* data, UErrorCode &status);

    /** @internal */

    friend class RBBIRuleBuilder;

    /** @internal */

    friend class BreakIterator;

public:

    /** Default constructor.  Creates an empty shell of an iterator, with no

     *  rules or text to iterate over.   Object can subsequently be assigned to.

     *  @stable ICU 2.2

     */

    RuleBasedBreakIterator();

    /**

     * Copy constructor.  Will produce a break iterator with the same behavior,

     * and which iterates over the same text, as the one passed in.

     * @param that The RuleBasedBreakIterator passed to be copied

     * @stable ICU 2.0

     */

    RuleBasedBreakIterator(const RuleBasedBreakIterator& that);

    /**

     * Construct a RuleBasedBreakIterator from a set of rules supplied as a string.

     * @param rules The break rules to be used.

     * @param parseError  In the event of a syntax error in the rules, provides the location

     *                    within the rules of the problem.

     * @param status Information on any errors encountered.

     * @stable ICU 2.2

     */

    RuleBasedBreakIterator( const UnicodeString    &rules,

                             UParseError           &parseError,

                             UErrorCode            &status);

    /**

     * This constructor uses the udata interface to create a BreakIterator

     * whose internal tables live in a memory-mapped file.  "image" is an

     * ICU UDataMemory handle for the pre-compiled break iterator tables.

     * @param image handle to the memory image for the break iterator data.

     *        Ownership of the UDataMemory handle passes to the Break Iterator,

     *        which will be responsible for closing it when it is no longer needed.

     * @param status Information on any errors encountered.

     * @see udata_open

     * @see #getBinaryRules

     * @stable ICU 2.8

     */

    RuleBasedBreakIterator(UDataMemory* image, UErrorCode &status);

    /**

     * Destructor

     *  @stable ICU 2.0

     */

    virtual ~RuleBasedBreakIterator();

    /**

     * Assignment operator.  Sets this iterator to have the same behavior,

     * and iterate over the same text, as the one passed in.

     * @param that The RuleBasedBreakItertor passed in

     * @return the newly created RuleBasedBreakIterator

     *  @stable ICU 2.0

     */

    RuleBasedBreakIterator& operator=(const RuleBasedBreakIterator& that);

    /**

     * Equality operator.  Returns TRUE if both BreakIterators are of the

     * same class, have the same behavior, and iterate over the same text.

     * @param that The BreakIterator to be compared for equality

     * @return TRUE if both BreakIterators are of the

     * same class, have the same behavior, and iterate over the same text.

     *  @stable ICU 2.0

     */

    virtual UBool operator==(const BreakIterator& that) const;

    /**

     * Not-equal operator.  If operator== returns TRUE, this returns FALSE,

     * and vice versa.

     * @param that The BreakIterator to be compared for inequality

     * @return TRUE if both BreakIterators are not same.

     *  @stable ICU 2.0

     */

    UBool operator!=(const BreakIterator& that) const;

    /**

     * Returns a newly-constructed RuleBasedBreakIterator with the same

     * behavior, and iterating over the same text, as this one.

     * Differs from the copy constructor in that it is polymorphic, and

     * will correctly clone (copy) a derived class.

     * clone() is thread safe.  Multiple threads may simultaeneously

     * clone the same source break iterator.

     * @return a newly-constructed RuleBasedBreakIterator

     * @stable ICU 2.0

     */

    virtual BreakIterator* clone() const;

    /**

     * Compute a hash code for this BreakIterator

     * @return A hash code

     *  @stable ICU 2.0

     */

    virtual int32_t hashCode(void) const;

    /**

     * Returns the description used to create this iterator

     * @return the description used to create this iterator

     *  @stable ICU 2.0

     */

    virtual const UnicodeString& getRules(void) const;

    //=======================================================================

    // BreakIterator overrides

    //=======================================================================

    /**

     * Return a CharacterIterator over the text being analyzed.  This version

     * of this method returns the actual CharacterIterator we're using internally.

     * Changing the state of this iterator can have undefined consequences.  If

     * you need to change it, clone it first.

     * @return An iterator over the text being analyzed.

     *  @stable ICU 2.0

     */

    virtual const CharacterIterator& getText(void) const;

    /**

      *  Get a UText for the text being analyzed.

      *  The returned UText is a shallow clone of the UText used internally

      *  by the break iterator implementation.  It can safely be used to

      *  access the text without impacting any break iterator operations,

      *  but the underlying text itself must not be altered.

      *

      * @param fillIn A UText to be filled in.  If NULL, a new UText will be

      *           allocated to hold the result.

      * @param status receives any error codes.

      * @return   The current UText for this break iterator.  If an input

      *           UText was provided, it will always be returned.

      * @draft ICU 3.4

      */

     virtual UText *getUText(UText *fillIn, UErrorCode &status) const;

    /**

     * Set the iterator to analyze a new piece of text.  This function resets

     * the current iteration position to the beginning of the text.

     * @param newText An iterator over the text to analyze.  The BreakIterator

     * takes ownership of the character iterator.  The caller MUST NOT delete it!

     *  @stable ICU 2.0

     */

    virtual void adoptText(CharacterIterator* newText);

    /**

     * Set the iterator to analyze a new piece of text.  This function resets

     * the current iteration position to the beginning of the text.

     * @param newText The text to analyze.

     *  @stable ICU 2.0

     */

    virtual void setText(const UnicodeString& newText);

    /**

     * Reset the break iterator to operate over the text represented by

     * the UText.  The iterator position is reset to the start.

     *

     * This function makes a shallow clone of the supplied UText.  This means

     * that the caller is free to immediately close or otherwise reuse the

     * Utext that was passed as a parameter, but that the underlying text itself

     * must not be altered while being referenced by the break iterator.

     *

     * @param text    The UText used to change the text.

     * @param status  Receives any error codes.

     * @draft ICU 3.4

     */

    virtual void  setText(UText *text, UErrorCode &status);

    /**

     * Sets the current iteration position to the beginning of the text.

     * (i.e., the CharacterIterator's starting offset).

     * @return The offset of the beginning of the text.

     *  @stable ICU 2.0

     */

    virtual int32_t first(void);

    /**

     * Sets the current iteration position to the end of the text.

     * (i.e., the CharacterIterator's ending offset).

     * @return The text's past-the-end offset.

     *  @stable ICU 2.0

     */

    virtual int32_t last(void);

    /**

     * Advances the iterator either forward or backward the specified number of steps.

     * Negative values move backward, and positive values move forward.  This is

     * equivalent to repeatedly calling next() or previous().

     * @param n The number of steps to move.  The sign indicates the direction

     * (negative is backwards, and positive is forwards).

     * @return The character offset of the boundary position n boundaries away from

     * the current one.

     *  @stable ICU 2.0

     */

    virtual int32_t next(int32_t n);

    /**

     * Advances the iterator to the next boundary position.

     * @return The position of the first boundary after this one.

     *  @stable ICU 2.0

     */

    virtual int32_t next(void);

    /**

     * Moves 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 true if the specfied position is a boundary position.  As a side

     * effect, leaves the iterator pointing to the first boundary position at

     * or after "offset".

     * @param offset the offset to check.

     * @return True if "offset" is a boundary position.

     *  @stable ICU 2.0

     */

    virtual UBool isBoundary(int32_t offset);

    /**

     * Returns the current iteration position.

     * @return The current iteration position.

     * @stable ICU 2.0

     */

    virtual int32_t current(void) const;

    /**

     * Return the status tag from the break rule that determined the most recently

     * returned break position.  For break rules that do not specify a

     * status, a default value of 0 is returned.  If more than one break rule

     * would cause a boundary to be located at some position in the text,

     * the numerically largest of the applicable status values is returned.

     * <p>

     * Of the standard types of ICU break iterators, only word break and

     * line break provide status values.  The values are defined in

     * the header file ubrk.h.  For Word breaks, the status allows distinguishing between words

     * that contain alphabetic letters, "words" that appear to be numbers,

     * punctuation and spaces, words containing ideographic characters, and

     * more.  For Line Break, the status distinguishes between hard (mandatory) breaks

     * and soft (potential) break positions.

     * <p>

     * <code>getRuleStatus()</code> can be called after obtaining a boundary

     * position from <code>next()</code>, <code>previous()</code>, or

     * any other break iterator functions that returns a boundary position.

     * <p>

     * When creating custom break rules, one is free to define whatever

     * status values may be convenient for the application.

     * <p>

     * Note: this function is not thread safe.  It should not have been

     *       declared const, and the const remains only for compatibility

     *       reasons.  (The function is logically const, but not bit-wise const).

     * <p>

     * @return the status from the break rule that determined the most recently

     * returned break position.

     *

     * @see UWordBreak

     * @stable ICU 2.2

     */

    virtual int32_t getRuleStatus() const;

   /**

    * Get the status (tag) values from the break rule(s) that determined the most

    * recently returned break position.

    * <p>

    * The returned status value(s) are stored into an array provided by the caller.

    * The values are stored in sorted (ascending) order.

    * If the capacity of the output array is insufficient to hold the data,

    *  the output will be truncated to the available length, and a

    *  U_BUFFER_OVERFLOW_ERROR will be signaled.

    *

    * @param fillInVec an array to be filled in with the status values.

    * @param capacity  the length of the supplied vector.  A length of zero causes

    *                  the function to return the number of status values, in the

    *                  normal way, without attemtping to store any values.

    * @param status    receives error codes.

    * @return          The number of rule status values from rules that determined

    *                  the most recent boundary returned by the break iterator.

    *                  In the event of a U_BUFFER_OVERFLOW_ERROR, the return value

    *                  is the total number of status values that were available,

    *                  not the reduced number that were actually returned.

    * @see getRuleStatus

    * @draft ICU 3.0

    */

    virtual int32_t getRuleStatusVec(int32_t *fillInVec, int32_t capacity, UErrorCode &status);

    /**

     * 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;

    /**

     * 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 U_EXPORT2 getStaticClassID(void);

    /*

     * Create a clone (copy) of this break iterator in memory provided

     *  by the caller.  The idea is to increase performance by avoiding

     *  a storage allocation.  Use of this functoin is NOT RECOMMENDED.

     *  Performance gains are minimal, and correct buffer management is

     *  tricky.  Use clone() instead.

     *

     * @param stackBuffer  The pointer to the memory into which the cloned object

     *                     should be placed.  If NULL,  allocate heap memory

     *                     for the cloned object.

     * @param BufferSize   The size of the buffer.  If zero, return the required

     *                     buffer size, but do not clone the object.  If the

     *                     size was too small (but not zero), allocate heap

     *                     storage for the cloned object.

     *

     * @param status       Error status.  U_SAFECLONE_ALLOCATED_WARNING will be

     *                     returned if the the provided buffer was too small, and

     *                     the clone was therefore put on the heap.

     *

     * @return  Pointer to the clone object.  This may differ from the stackBuffer

     *          address if the byte alignment of the stack buffer was not suitable

     *          or if the stackBuffer was too small to hold the clone.

     * @stable ICU 2.0

     */

    virtual BreakIterator *  createBufferClone(void *stackBuffer,

                                               int32_t &BufferSize,

                                               UErrorCode &status);

    /**

     * Return the binary form of compiled break rules,

     * which can then be used to create a new break iterator at some

     * time in the future.  Creating a break iterator from pre-compiled rules

     * is much faster than building one from the source form of the

     * break rules.

     *

     * The binary data can only be used with the same version of ICU

     *  and on the same platform type (processor endian-ness)

     *

     * @param length Returns the length of the binary data.  (Out paramter.)

     *

     * @return   A pointer to the binary (compiled) rule data.  The storage

     *           belongs to the RulesBasedBreakIterator object, not the

     *           caller, and must not be modified or deleted.

     * @internal

     */

    virtual const uint8_t *getBinaryRules(uint32_t &length);

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);

    /**

     * This method backs the iterator back up to a "safe position" in the text.

     * This is a position that we know, without any context, must be a break position.

     * The various calling methods then iterate forward from this safe position to

     * the appropriate position to return.  (For more information, see the description

     * of buildBackwardsStateTable() in RuleBasedBreakIterator.Builder.)

     * @internal

     */

    virtual int32_t handlePrevious(void);

    /**

     * Dumps caches and performs other actions associated with a complete change

     * in text or iteration position.  This function is a no-op in RuleBasedBreakIterator,

     * but subclasses can and do override it.

     * @internal

     */

    virtual void reset(void);

    /**

      * Return true if the category lookup for this char

      * indicates that it is in the set of dictionary lookup chars.

      * This function is intended for use by dictionary based break iterators.

      * @return true if the category lookup for this char

      * indicates that it is in the set of dictionary lookup chars.

      * @internal

      */

    virtual UBool isDictionaryChar(UChar32);

    /**

      * Common initialization function, used by constructors and bufferClone.

      *   (Also used by DictionaryBasedBreakIterator::createBufferClone().)

      * @internal

      */

    void init();

private:

    /**

     * This method backs the iterator back up to a "safe position" in the text.

     * This is a position that we know, without any context, must be a break position.

     * The various calling methods then iterate forward from this safe position to

     * the appropriate position to return.  (For more information, see the description

     * of buildBackwardsStateTable() in RuleBasedBreakIterator.Builder.)

     * @param statetable state table used of moving backwards

     * @internal

     */

    int32_t handlePrevious(const RBBIStateTable *statetable);

    /**

     * 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.

     * @param statetable state table used of moving forwards

     * @internal

     */

    int32_t handleNext(const RBBIStateTable *statetable);

    /**

     *  @internal

     */

    void makeRuleStatusValid();

};

//------------------------------------------------------------------------------

//

//   Inline Functions Definitions ...

//

//------------------------------------------------------------------------------

inline UBool RuleBasedBreakIterator::operator!=(const BreakIterator& that) const {

    return !operator==(that);

}

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_BREAK_ITERATION */

#endif