// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ******************************************************************************* * * Copyright (C) 2002-2011 International Business Machines * Corporation and others. All Rights Reserved. * ******************************************************************************* * file name: uiter.h * encoding: UTF-8 * 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" #if U_SHOW_CPLUSPLUS_API U_NAMESPACE_BEGIN class CharacterIterator; class Replaceable; U_NAMESPACE_END #endif U_CDECL_BEGIN 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 */ UCharIteratorOrigin; /** Constants for UCharIterator. @stable ICU 2.6 */ enum { … }; /** * 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 … /** * 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 */ UCharIteratorGetIndex; /** * 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 */ UCharIteratorMove; /** * 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 */ UCharIteratorHasNext; /** * 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 */ UCharIteratorHasPrevious; /** * 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 */ UCharIteratorCurrent; /** * 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 */ UCharIteratorNext; /** * 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 */ UCharIteratorPrevious; /** * 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 */ UCharIteratorReserved; /** * 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 */ UCharIteratorGetState; /** * 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 */ UCharIteratorSetState; /** * 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 { … }; /** * 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI void U_EXPORT2 uiter_setUTF8(UCharIterator *iter, const char *s, int32_t length); #if U_SHOW_CPLUSPLUS_API /** * 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_CAPI void U_EXPORT2 uiter_setCharacterIterator(UCharIterator *iter, icu::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_CAPI void U_EXPORT2 uiter_setReplaceable(UCharIterator *iter, const icu::Replaceable *rep); #endif U_CDECL_END #endif
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