/*

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

 *

 *   Copyright (C) 2002-2005, International Business Machines

 *   Corporation and others.  All Rights Reserved.

 *

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

 *   file name:  uiter.h

 *   encoding:   US-ASCII

 *   tab size:   8 (not used)

 *   indentation:4

 *

 *   created on: 2002jan18

 *   created by: Markus W. Scherer

 */

 #ifndef __UITER_H__

 #define __UITER_H__

 /**

  * \file

  * \brief C API: Unicode Character Iteration

  *

  * @see UCharIterator

  */

 #include "unicode/utypes.h"

 #ifdef XP_CPLUSPLUS

     U_NAMESPACE_BEGIN

     class CharacterIterator;

     class Replaceable;

     U_NAMESPACE_END

 #endif

 U_CDECL_BEGIN

 struct UCharIterator;

 typedef struct UCharIterator UCharIterator; /**< C typedef for struct UCharIterator. @stable ICU 2.1 */

 /**

  * Origin constants for UCharIterator.getIndex() and UCharIterator.move().

  * @see UCharIteratorMove

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef enum UCharIteratorOrigin {

     UITER_START, UITER_CURRENT, UITER_LIMIT, UITER_ZERO, UITER_LENGTH

 } UCharIteratorOrigin;

 /** Constants for UCharIterator. @stable ICU 2.6 */

 enum {

     /**

      * Constant value that may be returned by UCharIteratorMove

      * indicating that the final UTF-16 index is not known, but that the move succeeded.

      * This can occur when moving relative to limit or length, or

      * when moving relative to the current index after a setState()

      * when the current UTF-16 index is not known.

      *

      * It would be very inefficient to have to count from the beginning of the text

      * just to get the current/limit/length index after moving relative to it.

      * The actual index can be determined with getIndex(UITER_CURRENT)

      * which will count the UChars if necessary.

      *

      * @stable ICU 2.6

      */

     UITER_UNKNOWN_INDEX=-2

 };

 /**

  * Constant for UCharIterator getState() indicating an error or

  * an unknown state.

  * Returned by uiter_getState()/UCharIteratorGetState

  * when an error occurs.

  * Also, some UCharIterator implementations may not be able to return

  * a valid state for each position. This will be clearly documented

  * for each such iterator (none of the public ones here).

  *

  * @stable ICU 2.6

  */

 #define UITER_NO_STATE ((uint32_t)0xffffffff)

 /**

  * Function type declaration for UCharIterator.getIndex().

  *

  * Gets the current position, or the start or limit of the

  * iteration range.

  *

  * This function may perform slowly for UITER_CURRENT after setState() was called,

  * or for UITER_LENGTH, because an iterator implementation may have to count

  * UChars if the underlying storage is not UTF-16.

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @param origin get the 0, start, limit, length, or current index

  * @return the requested index, or U_SENTINEL in an error condition

  *

  * @see UCharIteratorOrigin

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef int32_t U_CALLCONV

 UCharIteratorGetIndex(UCharIterator *iter, UCharIteratorOrigin origin);

 /**

  * Function type declaration for UCharIterator.move().

  *

  * Use iter->move(iter, index, UITER_ZERO) like CharacterIterator::setIndex(index).

  *

  * 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.

  * Out of bounds movement will be pinned to the start or limit.

  *

  * This function may perform slowly for moving relative to UITER_LENGTH

  * because an iterator implementation may have to count the rest of the

  * UChars if the native storage is not UTF-16.

  *

  * When moving relative to the limit or length, or

  * relative to the current position after setState() was called,

  * move() may return UITER_UNKNOWN_INDEX (-2) to avoid an inefficient

  * determination of the actual UTF-16 index.

  * The actual index can be determined with getIndex(UITER_CURRENT)

  * which will count the UChars if necessary.

  * See UITER_UNKNOWN_INDEX for details.

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @param delta can be positive, zero, or negative

  * @param origin move relative to the 0, start, limit, length, or current index

  * @return the new index, or U_SENTINEL on an error condition,

  *         or UITER_UNKNOWN_INDEX when the index is not known.

  *

  * @see UCharIteratorOrigin

  * @see UCharIterator

  * @see UITER_UNKNOWN_INDEX

  * @stable ICU 2.1

  */

 typedef int32_t U_CALLCONV

 UCharIteratorMove(UCharIterator *iter, int32_t delta, UCharIteratorOrigin origin);

 /**

  * Function type declaration for UCharIterator.hasNext().

  *

  * Check if current() and next() can still

  * return another code unit.

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @return boolean value for whether current() and next() can still return another code unit

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef UBool U_CALLCONV

 UCharIteratorHasNext(UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.hasPrevious().

  *

  * Check if previous() can still return another code unit.

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @return boolean value for whether previous() can still return another code unit

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef UBool U_CALLCONV

 UCharIteratorHasPrevious(UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.current().

  *

  * Return the code unit at the current position,

  * or U_SENTINEL if there is none (index is at the limit).

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @return the current code unit

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef UChar32 U_CALLCONV

 UCharIteratorCurrent(UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.next().

  *

  * 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).

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @return the current code unit (and post-increment the current index)

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef UChar32 U_CALLCONV

 UCharIteratorNext(UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.previous().

  *

  * 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).

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @return the previous code unit (after pre-decrementing the current index)

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef UChar32 U_CALLCONV

 UCharIteratorPrevious(UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.reservedFn().

  * Reserved for future use.

  *

  * @param iter the UCharIterator structure ("this pointer")

  * @param something some integer argument

  * @return some integer

  *

  * @see UCharIterator

  * @stable ICU 2.1

  */

 typedef int32_t U_CALLCONV

 UCharIteratorReserved(UCharIterator *iter, int32_t something);

 /**

  * Function type declaration for UCharIterator.getState().

  *

  * Get the "state" of the iterator in the form of a single 32-bit word.

  * It is recommended that the state value be calculated to be as small as

  * is feasible. For strings with limited lengths, fewer than 32 bits may

  * be sufficient.

  *

  * This is used together with setState()/UCharIteratorSetState

  * to save and restore the iterator position more efficiently than with

  * getIndex()/move().

  *

  * The iterator state is defined as a uint32_t value because it is designed

  * for use in ucol_nextSortKeyPart() which provides 32 bits to store the state

  * of the character iterator.

  *

  * With some UCharIterator implementations (e.g., UTF-8),

  * getting and setting the UTF-16 index with existing functions

  * (getIndex(UITER_CURRENT) followed by move(pos, UITER_ZERO)) is possible but

  * relatively slow because the iterator has to "walk" from a known index

  * to the requested one.

  * This takes more time the farther it needs to go.

  *

  * An opaque state value allows an iterator implementation to provide

  * an internal index (UTF-8: the source byte array index) for

  * fast, constant-time restoration.

  *

  * After calling setState(), a getIndex(UITER_CURRENT) may be slow because

  * the UTF-16 index may not be restored as well, but the iterator can deliver

  * the correct text contents and move relative to the current position

  * without performance degradation.

  *

  * 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 UCharIteratorSetState

  * @see UITER_NO_STATE

  * @stable ICU 2.6

  */

 typedef uint32_t U_CALLCONV

 UCharIteratorGetState(const UCharIterator *iter);

 /**

  * Function type declaration for UCharIterator.setState().

  *

  * Restore the "state" of the iterator using a state word from a getState() call.

  * The iterator object need not be the same one as for which getState() was called,

  * but it must be of the same type (set up using the same uiter_setXYZ function)

  * and it must iterate over the same string

  * (binary identical regardless of memory address).

  * For more about the state word see UCharIteratorGetState.

  *

  * After calling setState(), a getIndex(UITER_CURRENT) may be slow because

  * the UTF-16 index may not be restored as well, but the iterator can deliver

  * the correct text contents and move relative to the current position

  * without performance degradation.

  *

  * @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 UCharIteratorGetState

  * @stable ICU 2.6

  */

 typedef void U_CALLCONV

 UCharIteratorSetState(UCharIterator *iter, uint32_t state, UErrorCode *pErrorCode);

 /**

  * C API for code unit iteration.

  * This can be used as a C wrapper around

  * CharacterIterator, Replaceable, or implemented using simple strings, etc.

  *

  * There are two roles for using UCharIterator:

  *

  * A "provider" sets the necessary function pointers and controls the "protected"

  * fields of the UCharIterator structure. A "provider" passes a UCharIterator

  * into C APIs that need a UCharIterator as an abstract, flexible string interface.

  *

  * Implementations of such C APIs are "callers" of UCharIterator functions;

  * they only use the "public" function pointers and never access the "protected"

  * fields directly.

  *

  * The current() and next() functions only check the current index against the

  * limit, and previous() only checks the current index against the start,

  * to see if the iterator already reached the end of the iteration range.

  *

  * The assumption - in all iterators - is that the index is moved via the API,

  * which means it won't go out of bounds, or the index is modified by

  * user code that knows enough about the iterator implementation to set valid

  * index values.

  *

  * UCharIterator functions return code unit values 0..0xffff,

  * or U_SENTINEL if the iteration bounds are reached.

  *

  * @stable ICU 2.1

  */

 struct UCharIterator {

     /**

      * (protected) Pointer to string or wrapped object or similar.

      * Not used by caller.

      * @stable ICU 2.1

      */

     const void *context;

     /**

      * (protected) Length of string or similar.

      * Not used by caller.

      * @stable ICU 2.1

      */

     int32_t length;

     /**

      * (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