text: // © 2016 and later: Unicode, Inc. and others.
  // License & terms of use: http://www.unicode.org/copyright.html
  /*
  *******************************************************************************
  *   Copyright (C) 2001-2014, International Business Machines
  *   Corporation and others.  All Rights Reserved.
  *******************************************************************************
  *
  * File ucoleitr.h
  *
  * Modification History:
  *
  * Date        Name        Description
  * 02/15/2001  synwee      Modified all methods to process its own function 
  *                         instead of calling the equivalent c++ api (coleitr.h)
  *******************************************************************************/
  
  #ifndef UCOLEITR_H
  #define UCOLEITR_H
  
  #include "unicode/utypes.h"
  
  #if !UCONFIG_NO_COLLATION
  
  /**  
   * This indicates an error has occured during processing or if no more CEs is 
   * to be returned.
   * @stable ICU 2.0
   */
  #define UCOL_NULLORDER        ((int32_t)0xFFFFFFFF)
  
  #include "unicode/ucol.h"
  
  /** 
   * The UCollationElements struct.
   * For usage in C programs.
   * @stable ICU 2.0
   */
  typedef struct UCollationElements UCollationElements;
  
  /**
   * \file
   * \brief C API: UCollationElements
   *
   * The UCollationElements API is used as an iterator to walk through each 
   * character of an international string. Use the iterator to return the
   * ordering priority of the positioned character. The ordering priority of a 
   * character, which we refer to as a key, defines how a character is collated 
   * in the given collation object.
   * For example, consider the following in Slovak and in traditional Spanish collation:
   * <pre>
   * .       "ca" -> the first key is key('c') and second key is key('a').
   * .       "cha" -> the first key is key('ch') and second key is key('a').
   * </pre>
   * And in German phonebook collation,
   * <pre>
   * .       "<ae ligature>b"-> the first key is key('a'), the second key is key('e'), and
   * .       the third key is key('b').
   * </pre>
   * <p>Example of the iterator usage: (without error checking)
   * <pre>
   * .  void CollationElementIterator_Example()
   * .  {
   * .      UChar *s;
   * .      t_int32 order, primaryOrder;
   * .      UCollationElements *c;
   * .      UCollatorOld *coll;
   * .      UErrorCode success = U_ZERO_ERROR;
   * .      s=(UChar*)malloc(sizeof(UChar) * (strlen("This is a test")+1) );
   * .      u_uastrcpy(s, "This is a test");
   * .      coll = ucol_open(NULL, &success);
   * .      c = ucol_openElements(coll, str, u_strlen(str), &status);
   * .      order = ucol_next(c, &success);
   * .      ucol_reset(c);
   * .      order = ucol_prev(c, &success);
   * .      free(s);
   * .      ucol_close(coll);
   * .      ucol_closeElements(c);
   * .  }
   * </pre>
   * <p>
   * ucol_next() returns the collation order of the next.
   * ucol_prev() returns the collation order of the previous character.
   * The Collation Element Iterator moves only in one direction between calls to
   * ucol_reset. That is, ucol_next() and ucol_prev can not be inter-used. 
   * Whenever ucol_prev is to be called after ucol_next() or vice versa, 
   * ucol_reset has to be called first to reset the status, shifting pointers to 
   * either the end or the start of the string. Hence at the next call of 
   * ucol_prev or ucol_next, the first or last collation order will be returned. 
   * If a change of direction is done without a ucol_reset, the result is 
   * undefined.
   * The result of a forward iterate (ucol_next) and reversed result of the  
   * backward iterate (ucol_prev) on the same string are equivalent, if 
   * collation orders with the value 0 are ignored.
   * Character based on the comparison level of the collator.  A collation order 
   * consists of primary order, secondary order and tertiary order.  The data 
   * type of the collation order is <strong>int32_t</strong>. 
   *
   * @see UCollator
   */
  
  /**
   * Open the collation elements for a string.
   *
   * @param coll The collator containing the desired collation rules.
   * @param text The text to iterate over.
   * @param textLength The number of characters in text, or -1 if null-terminated
   * @param status A pointer to a UErrorCode to receive any errors.
   * @return a struct containing collation element information
   * @stable ICU 2.0
   */
  U_STABLE UCollationElements* U_EXPORT2 
  ucol_openElements(const UCollator  *coll,
                    const UChar      *text,
                          int32_t    textLength,
                          UErrorCode *status);
  
  
  /**
   * get a hash code for a key... Not very useful!
   * @param key    the given key.
   * @param length the size of the key array.
   * @return       the hash code.
   * @stable ICU 2.0
   */
  U_STABLE int32_t U_EXPORT2 
  ucol_keyHashCode(const uint8_t* key, int32_t length);
  
  /**
   * Close a UCollationElements.
   * Once closed, a UCollationElements may no longer be used.
   * @param elems The UCollationElements to close.
   * @stable ICU 2.0
   */
  U_STABLE void U_EXPORT2 
  ucol_closeElements(UCollationElements *elems);
  
  /**
   * Reset the collation elements to their initial state.
   * This will move the 'cursor' to the beginning of the text.
   * Property settings for collation will be reset to the current status.
   * @param elems The UCollationElements to reset.
   * @see ucol_next
   * @see ucol_previous
   * @stable ICU 2.0
   */
  U_STABLE void U_EXPORT2 
  ucol_reset(UCollationElements *elems);
  
  /**
   * Get the ordering priority of the next collation element in the text.
   * A single character may contain more than one collation element.
   * @param elems The UCollationElements containing the text.
   * @param status A pointer to a UErrorCode to receive any errors.
   * @return The next collation elements ordering, otherwise returns UCOL_NULLORDER 
   *         if an error has occured or if the end of string has been reached
   * @stable ICU 2.0
   */
  U_STABLE int32_t U_EXPORT2 
  ucol_next(UCollationElements *elems, UErrorCode *status);
  
  /**
   * Get the ordering priority of the previous collation element in the text.
   * A single character may contain more than one collation element.
   * Note that internally a stack is used to store buffered collation elements. 
   * @param elems The UCollationElements containing the text.
   * @param status A pointer to a UErrorCode to receive any errors. Noteably 
   *               a U_BUFFER_OVERFLOW_ERROR is returned if the internal stack
   *               buffer has been exhausted.
   * @return The previous collation elements ordering, otherwise returns 
   *         UCOL_NULLORDER if an error has occured or if the start of string has 
   *         been reached.
   * @stable ICU 2.0
   */
  U_STABLE int32_t U_EXPORT2 
  ucol_previous(UCollationElements *elems, UErrorCode *status);
  
  /**
   * Get the maximum length of any expansion sequences that end with the 
   * specified comparison order.
   * This is useful for .... ?
   * @param elems The UCollationElements containing the text.
   * @param order A collation order returned by previous or next.
   * @return maximum size of the expansion sequences ending with the collation 
   *         element or 1 if collation element does not occur at the end of any 
   *         expansion sequence
   * @stable ICU 2.0
   */
  U_STABLE int32_t U_EXPORT2 
  ucol_getMaxExpansion(const UCollationElements *elems, int32_t order);
  
  /**
   * Set the text containing the collation elements.
   * Property settings for collation will remain the same.
   * In order to reset the iterator to the current collation property settings,
   * the API reset() has to be called.
   * @param elems The UCollationElements to set.
   * @param text The source text containing the collation elements.
   * @param textLength The length of text, or -1 if null-terminated.
   * @param status A pointer to a UErrorCode to receive any errors.
   * @see ucol_getText
   * @stable ICU 2.0
   */
  U_STABLE void U_EXPORT2 
  ucol_setText(      UCollationElements *elems, 
               const UChar              *text,
                     int32_t            textLength,
                     UErrorCode         *status);
  
  /**
   * Get the offset of the current source character.
   * This is an offset into the text of the character containing the current
   * collation elements.
   * @param elems The UCollationElements to query.
   * @return The offset of the current source character.
   * @see ucol_setOffset
   * @stable ICU 2.0
   */
  U_STABLE int32_t U_EXPORT2 
  ucol_getOffset(const UCollationElements *elems);
  
  /**
   * Set the offset of the current source character.
   * This is an offset into the text of the character to be processed.
   * Property settings for collation will remain the same.
   * In order to reset the iterator to the current collation property settings,
   * the API reset() has to be called.
   * @param elems The UCollationElements to set.
   * @param offset The desired character offset.
   * @param status A pointer to a UErrorCode to receive any errors.
   * @see ucol_getOffset
   * @stable ICU 2.0
   */
  U_STABLE void U_EXPORT2 
  ucol_setOffset(UCollationElements *elems,
                 int32_t        offset,
                 UErrorCode         *status);
  
  /**
  * Get the primary order of a collation order.
  * @param order the collation order
  * @return the primary order of a collation order.
  * @stable ICU 2.6
  */
  U_STABLE int32_t U_EXPORT2
  ucol_primaryOrder (int32_t order); 
  
  /**
  * Get the secondary order of a collation order.
  * @param order the collation order
  * @return the secondary order of a collation order.
  * @stable ICU 2.6
  */
  U_STABLE int32_t U_EXPORT2
  ucol_secondaryOrder (int32_t order); 
  
  /**
  * Get the tertiary order of a collation order.
  * @param order the collation order
  * @return the tertiary order of a collation order.
  * @stable ICU 2.6
  */
  U_STABLE int32_t U_EXPORT2
  ucol_tertiaryOrder (int32_t order); 
  
  #endif /* #if !UCONFIG_NO_COLLATION */
  
  #endif
  