Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/uiter.h

+/*
+*******************************************************************************
+*
+*   Copyright (C) 2002-2006,2009 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"
+
+#if U_SHOW_CPLUSPLUS_API
+    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);
+
+#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_STABLE void U_EXPORT2
+uiter_setCharacterIterator(UCharIterator *iter, U_NAMESPACE_QUALIFIER 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 U_NAMESPACE_QUALIFIER Replaceable *rep);
+
+#endif
+
+U_CDECL_END
+
+#endif