uiter.h

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     * (protected) Start index or similar.
     * Not used by caller.
     * @stable ICU 2.1
     */
    int32_t start;

    /**
     * (protected) Current index or similar.
     * Not used by caller.
     * @stable ICU 2.1
     */
    int32_t index;

    /**
     * (protected) Limit index or similar.
     * Not used by caller.
     * @stable ICU 2.1
     */
    int32_t limit;

    /**
     * (protected) Used by UTF-8 iterators and possibly others.
     * @stable ICU 2.1
     */
    int32_t reservedField;

    /**
     * (public) Returns the current position or the
     * start or limit index of the iteration range.
     *
     * @see UCharIteratorGetIndex
     * @stable ICU 2.1
     */
    UCharIteratorGetIndex *getIndex;

    /**
     * (public) Moves the current position relative to the start or limit of the
     * iteration range, or relative to the current position itself.
     * The movement is expressed in numbers of code units forward
     * or backward by specifying a positive or negative delta.
     *
     * @see UCharIteratorMove
     * @stable ICU 2.1
     */
    UCharIteratorMove *move;

    /**
     * (public) Check if current() and next() can still
     * return another code unit.
     *
     * @see UCharIteratorHasNext
     * @stable ICU 2.1
     */
    UCharIteratorHasNext *hasNext;

    /**
     * (public) Check if previous() can still return another code unit.
     *
     * @see UCharIteratorHasPrevious
     * @stable ICU 2.1
     */
    UCharIteratorHasPrevious *hasPrevious;

    /**
     * (public) Return the code unit at the current position,
     * or U_SENTINEL if there is none (index is at the limit).
     *
     * @see UCharIteratorCurrent
     * @stable ICU 2.1
     */
    UCharIteratorCurrent *current;

    /**
     * (public) Return the code unit at the current index and increment
     * the index (post-increment, like s[i++]),
     * or return U_SENTINEL if there is none (index is at the limit).
     *
     * @see UCharIteratorNext
     * @stable ICU 2.1
     */
    UCharIteratorNext *next;

    /**
     * (public) Decrement the index and return the code unit from there
     * (pre-decrement, like s[--i]),
     * or return U_SENTINEL if there is none (index is at the start).
     *
     * @see UCharIteratorPrevious
     * @stable ICU 2.1
     */
    UCharIteratorPrevious *previous;

    /**
     * (public) Reserved for future use. Currently NULL.
     *
     * @see UCharIteratorReserved
     * @stable ICU 2.1
     */
    UCharIteratorReserved *reservedFn;

    /**
     * (public) Return the state of the iterator, to be restored later with setState().
     * This function pointer is NULL if the iterator does not implement it.
     *
     * @see UCharIteratorGet
     * @stable ICU 2.6
     */
    UCharIteratorGetState *getState;

    /**
     * (public) Restore the iterator state from the state word from a call
     * to getState().
     * This function pointer is NULL if the iterator does not implement it.
     *
     * @see UCharIteratorSet
     * @stable ICU 2.6
     */
    UCharIteratorSetState *setState;
};

/**
 * Helper function for UCharIterator to get the code point
 * at the current index.
 *
 * Return the code point that includes the code unit at the current position,
 * or U_SENTINEL if there is none (index is at the limit).
 * If the current code unit is a lead or trail surrogate,
 * then the following or preceding surrogate is used to form
 * the code point value.
 *
 * @param iter the UCharIterator structure ("this pointer")
 * @return the current code point
 *
 * @see UCharIterator
 * @see U16_GET
 * @see UnicodeString::char32At()
 * @stable ICU 2.1
 */
U_STABLE UChar32 U_EXPORT2
uiter_current32(UCharIterator *iter);

/**
 * Helper function for UCharIterator to get the next code point.
 *
 * Return the code point at the current index and increment
 * the index (post-increment, like s[i++]),
 * or return U_SENTINEL if there is none (index is at the limit).
 *
 * @param iter the UCharIterator structure ("this pointer")
 * @return the current code point (and post-increment the current index)
 *
 * @see UCharIterator
 * @see U16_NEXT
 * @stable ICU 2.1
 */
U_STABLE UChar32 U_EXPORT2
uiter_next32(UCharIterator *iter);

/**
 * Helper function for UCharIterator to get the previous code point.
 *
 * Decrement the index and return the code point from there
 * (pre-decrement, like s[--i]),
 * or return U_SENTINEL if there is none (index is at the start).
 *
 * @param iter the UCharIterator structure ("this pointer")
 * @return the previous code point (after pre-decrementing the current index)
 *
 * @see UCharIterator
 * @see U16_PREV
 * @stable ICU 2.1
 */
U_STABLE UChar32 U_EXPORT2
uiter_previous32(UCharIterator *iter);

/**
 * Get the "state" of the iterator in the form of a single 32-bit word.
 * This is a convenience function that calls iter->getState(iter)
 * if iter->getState is not NULL;
 * if it is NULL or any other error occurs, then UITER_NO_STATE is returned.
 *
 * Some UCharIterator implementations may not be able to return
 * a valid state for each position, in which case they return UITER_NO_STATE instead.
 * This will be clearly documented for each such iterator (none of the public ones here).
 *
 * @param iter the UCharIterator structure ("this pointer")
 * @return the state word
 *
 * @see UCharIterator
 * @see UCharIteratorGetState
 * @see UITER_NO_STATE
 * @stable ICU 2.6
 */
U_STABLE uint32_t U_EXPORT2
uiter_getState(const UCharIterator *iter);

/**
 * Restore the "state" of the iterator using a state word from a getState() call.
 * This is a convenience function that calls iter->setState(iter, state, pErrorCode)
 * if iter->setState is not NULL; if it is NULL, then U_UNSUPPORTED_ERROR is set.
 *
 * @param iter the UCharIterator structure ("this pointer")
 * @param state the state word from a getState() call
 *              on a same-type, same-string iterator
 * @param pErrorCode Must be a valid pointer to an error code value,
 *                   which must not indicate a failure before the function call.
 *
 * @see UCharIterator
 * @see UCharIteratorSetState
 * @stable ICU 2.6
 */
U_STABLE void U_EXPORT2
uiter_setState(UCharIterator *iter, uint32_t state, UErrorCode *pErrorCode);

/**
 * Set up a UCharIterator to iterate over a string.
 *
 * Sets the UCharIterator function pointers for iteration over the string s
 * with iteration boundaries start=index=0 and length=limit=string length.
 * The "provider" may set the start, index, and limit values at any time
 * within the range 0..length.
 * The length field will be ignored.
 *
 * The string pointer s is set into UCharIterator.context without copying
 * or reallocating the string contents.
 *
 * getState() simply returns the current index.
 * move() will always return the final index.
 *
 * @param iter UCharIterator structure to be set for iteration
 * @param s String to iterate over
 * @param length Length of s, or -1 if NUL-terminated
 *
 * @see UCharIterator
 * @stable ICU 2.1
 */
U_STABLE void U_EXPORT2
uiter_setString(UCharIterator *iter, const UChar *s, int32_t length);

/**
 * Set up a UCharIterator to iterate over a UTF-16BE string
 * (byte vector with a big-endian pair of bytes per UChar).
 *
 * Everything works just like with a normal UChar iterator (uiter_setString),
 * except that UChars are assembled from byte pairs,
 * and that the length argument here indicates an even number of bytes.
 *
 * getState() simply returns the current index.
 * move() will always return the final index.
 *
 * @param iter UCharIterator structure to be set for iteration
 * @param s UTF-16BE string to iterate over
 * @param length Length of s as an even number of bytes, or -1 if NUL-terminated
 *               (NUL means pair of 0 bytes at even index from s)
 *
 * @see UCharIterator
 * @see uiter_setString
 * @stable ICU 2.6
 */
U_STABLE void U_EXPORT2
uiter_setUTF16BE(UCharIterator *iter, const char *s, int32_t length);

/**
 * Set up a UCharIterator to iterate over a UTF-8 string.
 *
 * Sets the UCharIterator function pointers for iteration over the UTF-8 string s
 * with UTF-8 iteration boundaries 0 and length.
 * The implementation counts the UTF-16 index on the fly and
 * lazily evaluates the UTF-16 length of the text.
 *
 * The start field is used as the UTF-8 offset, the limit field as the UTF-8 length.
 * When the reservedField is not 0, then it contains a supplementary code point
 * and the UTF-16 index is between the two corresponding surrogates.
 * At that point, the UTF-8 index is behind that code point.
 *
 * The UTF-8 string pointer s is set into UCharIterator.context without copying
 * or reallocating the string contents.
 *
 * getState() returns a state value consisting of
 * - the current UTF-8 source byte index (bits 31..1)
 * - a flag (bit 0) that indicates whether the UChar position is in the middle
 *   of a surrogate pair
 *   (from a 4-byte UTF-8 sequence for the corresponding supplementary code point)
 *
 * getState() cannot also encode the UTF-16 index in the state value.
 * move(relative to limit or length), or
 * move(relative to current) after setState(), may return UITER_UNKNOWN_INDEX.
 *
 * @param iter UCharIterator structure to be set for iteration
 * @param s UTF-8 string to iterate over
 * @param length Length of s in bytes, or -1 if NUL-terminated
 *
 * @see UCharIterator
 * @stable ICU 2.6
 */
U_STABLE void U_EXPORT2
uiter_setUTF8(UCharIterator *iter, const char *s, int32_t length);

#ifdef XP_CPLUSPLUS

/**
 * Set up a UCharIterator to wrap around a C++ CharacterIterator.
 *
 * Sets the UCharIterator function pointers for iteration using the
 * CharacterIterator charIter.
 *
 * The CharacterIterator pointer charIter is set into UCharIterator.context
 * without copying or cloning the CharacterIterator object.
 * The other "protected" UCharIterator fields are set to 0 and will be ignored.
 * The iteration index and boundaries are controlled by the CharacterIterator.
 *
 * getState() simply returns the current index.
 * move() will always return the final index.
 *
 * @param iter UCharIterator structure to be set for iteration
 * @param charIter CharacterIterator to wrap
 *
 * @see UCharIterator
 * @stable ICU 2.1
 */
U_STABLE void U_EXPORT2
uiter_setCharacterIterator(UCharIterator *iter, CharacterIterator *charIter);

/**
 * Set up a UCharIterator to iterate over a C++ Replaceable.
 *
 * Sets the UCharIterator function pointers for iteration over the
 * Replaceable rep with iteration boundaries start=index=0 and
 * length=limit=rep->length().
 * The "provider" may set the start, index, and limit values at any time
 * within the range 0..length=rep->length().
 * The length field will be ignored.
 *
 * The Replaceable pointer rep is set into UCharIterator.context without copying
 * or cloning/reallocating the Replaceable object.
 *
 * getState() simply returns the current index.
 * move() will always return the final index.
 *
 * @param iter UCharIterator structure to be set for iteration
 * @param rep Replaceable to iterate over
 *
 * @see UCharIterator
 * @stable ICU 2.1
 */
U_STABLE void U_EXPORT2
uiter_setReplaceable(UCharIterator *iter, const Replaceable *rep);

#endif

U_CDECL_END

#endif