/*

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

 *

 *   Copyright (C) 2004-2005, International Business Machines

 *   Corporation and others.  All Rights Reserved.

 *

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

 *   file name:  utext.h

 *   encoding:   US-ASCII

 *   tab size:   8 (not used)

 *   indentation:4

 *

 *   created on: 2004oct06

 *   created by: Markus W. Scherer

 */

 #ifndef __UTEXT_H__

 #define __UTEXT_H__

 /**

  * \file

  * \brief C API: Abstract Unicode Text API

  *

  * The Text Access API provides a means to allow text that is stored in alternative

  * formats to work with ICU services.  ICU normally operates on text that is

  * stored UTF-16 format, in (UChar *) arrays for the C APIs or as type

  * UnicodeString for C++ APIs.

  *

  * ICU Text Access allows other formats, such as UTF-8 or non-contiguous

  * UTF-16 strings, to be placed in a UText wrapper and then passed to ICU services.

  *

  * There are three general classes of usage for UText:

  *

  *     Application Level Use.  This is the simplest usage - applications would

  *     use one of the utext_open() functions on their input text, and pass

  *     the resulting UText to the desired ICU service.

  *

  *     Second is usage in ICU Services, such as break iteration, that will need to

  *     operate on input presented to them as a UText.  These implementations

  *     will need to use the iteration and related UText functions to gain

  *     access to the actual text.

  *

  *     The third class of UText users are "text providers."  These are the

  *     UText implementations for the various text storage formats.  An application

  *     or system with a unique text storage format can implement a set of

  *     UText provider functions for that format, which will then allow

  *     ICU services to operate on that format.

  *

  *

  * <em>Iterating over text</em>

  *

  * Here is sample code for a forward iteration over the contents of a UText

  *

  * \code

  *    UChar32  c;

  *    UText    *ut = whatever();

  *

  *    for (c=utext_next32From(ut, 0); c>=0; c=utext_next32(ut)) {

  *       // do whatever with the codepoint c here.

  *    }

  * \endcode

  *

  * And here is similar code to iterate in the reverse direction, from the end

  * of the text towards the beginning.

  *

  * \code

  *    UChar32  c;

  *    UText    *ut = whatever();

  *    int      textLength = utext_nativeLength(ut);

  *    for (c=utext_previous32From(ut, textLength); c>=0; c=utext_previous32(ut)) {

  *       // do whatever with the codepoint c here.

  *    }

  * \endcode

  *

  * <em>Characters and Indexing</em>

  *

  * Indexing into text by UText functions is nearly always in terms of the native

  * indexing of the underlying text storage.  The storage format could be UTF-8

  * or UTF-32, for example.  When coding to the UText access API, no assumptions

  * can be made regarding the size of characters, or how far an index

  * may move when iterating between characters.

  *

  * All indices supplied to UText functions are pinned to the length of the

  * text.  An out-of-bounds index is not considered to be an error, but is

  * adjusted to be in the range  0 <= index <= length of input text.

  *

  *

  * When an index position is returned from a UText function, it will be

  * a native index to the underlying text.  In the case of multi-unit characters,

  * it will  always refer to the first position of the character,

  * never to the interior.  This is essentially the same thing as saying that

  * a returned index will always point to a boundary between characters.

  *

  * When a native index is supplied to a UText function, all indices that

  * refer to any part of a multi-unit character representation are considered

  * to be equivalent.  In the case of multi-unit characters, an incoming index

  * will be logically normalized to refer to the start of the character.

  * 

  * It is possible to test whether a native index is on a code point boundary

  * by doing a utext_setNativeIndex() followed by a utext_getNativeIndex().

  * If the index is returned unchanged, it was on a code point boundary.  If

  * an adjusted index is returned, the original index referred to the

  * interior of a character.

  *

  */

 #include "unicode/utypes.h"

 #ifdef XP_CPLUSPLUS

 #include "unicode/rep.h"

 #include "unicode/unistr.h"

 #endif

 #ifndef U_HIDE_DRAFT_API

 U_CDECL_BEGIN

 struct UText;

 typedef struct UText UText; /**< C typedef for struct UText. @draft ICU 3.4 */

 struct UTextChunk;

 typedef struct UTextChunk UTextChunk; /**< C typedef for struct UTextChunk. @draft ICU 3.4 */

 /***************************************************************************************

  *

  *   C Functions for creating UText wrappers around various kinds of text strings.

  *

  ****************************************************************************************/

 /**

   * utext_close    Close function for UText instances.

   *                Cleans up, releases any resources being held by an

   *                open UText.

   * <p/>

   *   If the UText was originally allocated by one of the utext_open functions,

   *   the storage associated with the utext will also be freed.

   *   If the UText storage originated with the application, as it would with

   *   a local or static instance, the storage will not be deleted.

   *

   *   An open UText can be reset to refer to new string by using one of the utext_open()

   *   functions without first closing the UText.  

   *

   * @param ut  The UText to be closed.

   * @return    NULL if the UText struct was deleted by the close.  If the UText struct

   *            was originally provided by the caller to the open function, it is

   *            returned by this function, and may be safely used again in

   *            a subsequent utext_open.

   *

   * @draft ICU 3.4

   */

 U_DRAFT UText * U_EXPORT2

 utext_close(UText *ut);

 /**

  * Open a read-only UText implementation for UTF-8 strings.

  * 

  * \htmlonly

  * Any invalid UTF-8 in the input will be handled in this way:

  * a sequence of bytes that has the form of a truncated, but otherwise valid,

  * UTF-8 sequence will be replaced by a single unicode replacement character, \uFFFD. 

  * Any other illegal bytes will each be replaced by a \uFFFD.

  * \endhtmlonly

  * 

  * @param ut     Pointer to a UText struct.  If NULL, a new UText will be created.

  *               If non-NULL, must refer to an initialized UText struct, which will then

  *               be reset to reference the specified UTF-8 string.

  * @param s      A UTF-8 string

  * @param length The length of the UTF-8 string in bytes, or -1 if the string is

  *               zero terminated.

  * @param status Errors are returned here.

  * @return       A pointer to the UText.  If a pre-allocated UText was provided, it

  *               will always be used and returned.

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_openUTF8(UText *ut, const char *s, int32_t length, UErrorCode *status);

 /**

  * Open a read-only UText for UChar * string.

  * 

  * @param ut     Pointer to a UText struct.  If NULL, a new UText will be created.

  *               If non-NULL, must refer to an initialized UText struct, which will then

  *               be reset to reference the specified UChar string.

  * @param s      A UChar (UTF-16) string

  * @param length The number of UChars in the input string, or -1 if the string is

  *               zero terminated.

  * @param status Errors are returned here.

  * @return       A pointer to the UText.  If a pre-allocated UText was provided, it

  *               will always be used and returned.

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_openUChars(UText *ut, const UChar *s, int32_t length, UErrorCode *status);

 #ifdef XP_CPLUSPLUS

 /**

  * Open a writable UText for a non-const UnicodeString. 

  * 

  * @param ut      Pointer to a UText struct.  If NULL, a new UText will be created.

  *                 If non-NULL, must refer to an initialized UText struct, which will then

  *                 be reset to reference the specified input string.

  * @param s       A UnicodeString.

  * @param status Errors are returned here.

  * @return        Pointer to the UText.  If a UText was supplied as input, this

  *                 will always be used and returned.

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_openUnicodeString(UText *ut, UnicodeString *s, UErrorCode *status);

 /**

  * Open a UText for a const UnicodeString.   The resulting UText will not be writable.

  * 

  * @param ut    Pointer to a UText struct.  If NULL, a new UText will be created.

  *               If non-NULL, must refer to an initialized UText struct, which will then

  *               be reset to reference the specified input string.

  * @param s      A const UnicodeString to be wrapped.

  * @param status Errors are returned here.

  * @return       Pointer to the UText.  If a UText was supplied as input, this

  *               will always be used and returned.

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_openConstUnicodeString(UText *ut, const UnicodeString *s, UErrorCode *status);

 /**

  * Open a writable UText implementation for an ICU Replaceable object.

  * @param ut    Pointer to a UText struct.  If NULL, a new UText will be created.

  *               If non-NULL, must refer to an already existing UText, which will then

  *               be reset to reference the specified replaceable text.

  * @param rep    A Replaceable text object.

  * @param status Errors are returned here.

  * @return       Pointer to the UText.  If a UText was supplied as input, this

  *               will always be used and returned.

  * @see Replaceable

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_openReplaceable(UText *ut, Replaceable *rep, UErrorCode *status);

 #endif

 /**

   *  clone a UText.  Much like opening a UText where the source text is itself

   *  another UText.

   *

   *  A deep clone will copy both the UText data structures and the underlying text.

   *  The original and cloned UText will operate completely independently; modifications

   *  made to the text in one will not effect the other.  Text providers are not

   *  required to support deep clones.  The user of clone() must check the status return

   *  and be prepared to handle failures.

   *

   *  A shallow clone replicates only the UText data structures; it does not make

   *  a copy of the underlying text.  Shallow clones can be used as an efficient way to 

   *  have multiple iterators active in a single text string that is not being

   *  modified.

   *

   *  A shallow clone operation will not fail, barring truly exceptional conditions such

   *  as memory allocation failures.

   *

   *  A UText and its clone may be safely concurrently accessed by separate threads.

   *  This is true for both shallow and deep clones.

   *  It is the responsibility of the Text Provider to ensure that this thread safety

   *  constraint is met.

   *

   *  @param dest   A UText struct to be filled in with the result of the clone operation,

   *                or NULL if the clone function should heap-allocate a new UText struct.

   *  @param src    The UText to be cloned.

   *  @param deep   TRUE to request a deep clone, FALSE for a shallow clone.

   *  @param status Errors are returned here.  For deep clones, U_UNSUPPORTED_ERROR

   *                will be returned if the text provider is unable to clone the

   *                original text.

   *  @return       The newly created clone, or NULL if the clone operation failed.

   *  @draft ICU 3.4

   */

 U_DRAFT UText * U_EXPORT2

 utext_clone(UText *dest, const UText *src, UBool deep, UErrorCode *status);

 /*****************************************************************************

  *

  *   C Functions to work with the text represeted by a UText wrapper

  *

  *****************************************************************************/

 /**

   * Get the length of the text.  Depending on the characteristics

   * of the underlying text representation, this may be expensive.  

   * @see  utext_isLengthExpensive()

   *

   *

   * @param ut  the text to be accessed.

   * @return the length of the text, expressed in native units.

   *

   * @draft ICU 3.4

   */

 U_DRAFT int32_t U_EXPORT2

 utext_nativeLength(UText *ut);

 /**

  *  Return TRUE if calculating the length of the text could be expensive.

  *  Finding the length of NUL terminated strings is considered to be expensive.

  *

  *  Note that the value of this function may change

  *  as the result of other operations on a UText.

  *  Once the length of a string has been discovered, it will no longer

  *  be expensive to report it.

  *

  * @param ut the text to be accessed.

  * @return TRUE if determining the length of the text could be time consuming.

  * @draft ICU 3.4

  */

 U_DRAFT UBool U_EXPORT2

 utext_isLengthExpensive(const UText *ut);

 /**

  * Returns the code point at the requested index,

  * or U_SENTINEL (-1) if it is out of bounds.

  *

  * If the specified index points to the interior of a multi-unit

  * character - one of the trail bytes of a UTF-8 sequence, for example -

  * the complete code point will be returned.

  *

  * The iteration position will be set to the start of the returned code point.

  *

  * This function is roughly equivalent to the the sequence

  *    utext_setNativeIndex(index);

  *    utext_current32();

  * (There is a difference if the index is out of bounds by being less than zero)

  * 

  * @param ut the text to be accessed

  * @param nativeIndex the native index of the character to be accessed.  If the index points

  *        to other than the first unit of a multi-unit character, it will be adjusted

  *        to the start of the character.

  * @return the code point at the specified index.

  * @draft ICU 3.4

  */

 U_DRAFT UChar32 U_EXPORT2

 utext_char32At(UText *ut, int32_t nativeIndex);

 /**

  *

  * Get the code point at the current iteration position,

  * or U_SENTINEL (-1) if the iteration has reached the end of

  * the input text.

  *

  * @param ut the text to be accessed.

  * @return the Unicode code point at the current iterator position.

  * @draft ICU 3.4

  */

 U_DRAFT UChar32 U_EXPORT2

 utext_current32(UText *ut);

 /**

  * Get the code point at the current iteration position of the UText, and

  * advance the position to the first index following the character.

  * Returns U_SENTINEL (-1) if the position is at the end of the

  * text.

  * This is a post-increment operation

  *

  * An inline macro version of this function, UTEXT_NEXT32(), 

  * is available for performance critical use.

  *

  * @param ut the text to be accessed.

  * @return the Unicode code point at the iteration position.

  * @see UTEXT_NEXT32

  * @draft ICU 3.4

  */

 U_DRAFT UChar32 U_EXPORT2

 utext_next32(UText *ut);

 /**

  *  Move the iterator position to the character (code point) whose

  *  index precedes the current position, and return that character.

  *  This is a pre-decrement operation.

  *  Returns U_SENTINEL (-1) if the position is at the start of the  text.

  *  This is a pre-decrement operation.

  *

  * An inline macro version of this function, UTEXT_PREVIOUS32(), 

  * is available for performance critical use.

  *

  *  @param ut the text to be accessed.

  *  @return the previous UChar32 code point, or U_SENTINEL (-1) 

  *          if the iteration has reached the start of the text.

  *  @see UTEXT_PREVIOUS32

  *  @draft ICU 3.4

  */

 U_DRAFT UChar32 U_EXPORT2

 utext_previous32(UText *ut);

 /**

   * Set the iteration index, access the text for forward iteration,

   * and return the code point starting at or before that index.

   * Leave the iteration index at the start of the following code point.

   *

   * This function is the most efficient and convenient way to

   * begin a forward iteration.

   *

   *  @param ut the text to be accessed.

   *  @param nativeIndex Iteration index, in the native units of the text provider.

   *  @return Code point which starts at or before index,

   *         or U_SENTINEL (-1) if it is out of bounds.

   * @draft ICU 3.4

   */

 U_DRAFT UChar32 U_EXPORT2

 utext_next32From(UText *ut, int32_t nativeIndex);

 /**

   * Set the iteration index, and return the code point preceding the

   * one specified by the initial index.  Leave the iteration position

   * at the start of the returned code point.

   *

   * This function is the most efficient and convenient way to

   * begin a backwards iteration.

   *

   * @param ut the text to be accessed.

   * @param nativeIndex Iteration index in the native units of the text provider.

   * @return Code point preceding the one at the initial index,

   *         or U_SENTINEL (-1) if it is out of bounds.

   *

   * @draft ICU 3.4

   */

 U_DRAFT UChar32 U_EXPORT2

 utext_previous32From(UText *ut, int32_t nativeIndex);

 /**

   * Get the current iterator position, which can range from 0 to 

   * the length of the text.

   * The position is a native index into the input text, in whatever format it

   * may have, and may not always correspond to a UChar (UTF-16) index

   * into the text.  The returned position will always be aligned to a

   * code point boundary 

   *

   * @param ut the text to be accessed.

   * @return the current index position, in the native units of the text provider.

   * @draft ICU 3.4

   */

 U_DRAFT int32_t U_EXPORT2

 utext_getNativeIndex(UText *ut);

 /**

   * Set the current iteration position to the nearest code point

   * boundary at or preceding the specified index.

   * The index is in the native units of the original input text.

   * If the index is out of range, it will be trimmed to be within

   * the range of the input text.

   * <p/>

   * It will usually be more efficient to begin an iteration

   * using the functions utext_next32From() or utext_previous32From()

   * rather than setIndex().

   * <p/>

   * Moving the index position to an adjacent character is best done

   * with utext_next32(), utext_previous32() or utext_moveIndex32().

   * Attempting to do direct arithmetic on the index position is

   * complicated by the fact that the size (in native units) of a

   * character depends on the underlying representation of the character

   * (UTF-8, UTF-16, UTF-32, arbitrary codepage), and is not

   * easily knowable.

   *

   * @param ut the text to be accessed.

   * @param nativeIndex the native unit index of the new iteration position.

   * @draft ICU 3.4

   */

 U_DRAFT void U_EXPORT2

 utext_setNativeIndex(UText *ut, int32_t nativeIndex);

 /**

   * Move the iterator postion by delta code points.  The number of code points

   * is a signed number; a negative delta will move the iterator backwards,

   * towards the start of the text.

   * <p/>

   * The index is moved by <code>delta</code> code points

   * forward or backward, but no further backward than to 0 and

   * no further forward than to utext_nativeLength().

   * The resulting index value will be in between 0 and length, inclusive.

   * <p/>

   * Because the index is kept in the native units of the text provider, the

   * actual numeric amount by which the index moves depends on the

   * underlying text storage representation of the text provider.

   *

   * @param ut the text to be accessed.

   * @param delta the signed number of code points to move the iteration position.

   * @return TRUE if the position could be moved the requested number of positions while

   *              staying within the range [0 - text length].

   * @draft ICU 3.4

   */

 U_DRAFT UBool U_EXPORT2

 utext_moveIndex32(UText *ut, int32_t delta);

 /**

  *

  * Extract text from a UText into a UChar buffer.  The range of text to be extracted

  * is specified in the native indices of the UText provider.  These may not necessarily

  * be UTF-16 indices.

  * <p/>

  * The size (number of 16 bit UChars) in the data to be extracted is returned.  The

  * full number of UChars is returned, even when the extracted text is truncated

  * because the specified buffer size is too small.

  *

  * The extracted string will (if you are a user) / must (if you are a text provider)

  * be NUL-terminated if there is sufficient space in the destination buffer.  This

  * terminating NUL is not included in the returned length.

  *

  * @param  ut    the UText from which to extract data.

  * @param  nativeStart the native index of the first character to extract.

  * @param  nativeLimit the native string index of the position following the last

  *               character to extract.  If the specified limit is greater than the length

  *               of the text, the limit will be trimmed back to the text length.

  * @param  dest  the UChar (UTF-16) buffer into which the extracted text is placed

  * @param  destCapacity  The size, in UChars, of the destination buffer.  May be zero

  *               for precomputing the required size.

  * @param  status receives any error status.

  *         U_BUFFER_OVERFLOW_ERROR: the extracted text was truncated because the 

  *         buffer was too small.  Returns number of UChars for preflighting.

  * @return Number of UChars in the data to be extracted.  Does not include a trailing NUL.

  *

  * @draft ICU 3.4

  */

 U_DRAFT int32_t U_EXPORT2

 utext_extract(UText *ut,

              int32_t nativeStart, int32_t nativeLimit,

              UChar *dest, int32_t destCapacity,

              UErrorCode *status);

 /************************************************************************************

  *

  *  #define inline versions of selected performance-critical text access functions

  *          Caution:  do not use auto increment++ or decrement-- expressions

  *                    as parameters to these macros.

  *

  *          For most use, where there is no extreme performance constraint, the

  *          normal, non-inline functions are a better choice.  The resulting code

  *          will be smaller, and, if the need ever arises, easier to debug.

  *

  *          These are implemented as #defines rather than real functions

  *          because there is no fully portable way to do inline functions in plain C.

  *

  ************************************************************************************/

 /**

  * inline version of utext_next32(), for performance-critical situations.

  *

  * Get the code point at the current iteration position of the UText, and

  * advance the position to the first index following the character.

  * This is a post-increment operation.

  * Returns U_SENTINEL (-1) if the position is at the end of the

  * text.

  *

  * @draft ICU 3.4

  */

 #define UTEXT_NEXT32(ut)  \

     ((ut)->chunk.offset < (ut)->chunk.length && ((ut)->chunk.contents)[(ut)->chunk.offset]<0xd800 ? \

     ((ut)->chunk.contents)[((ut)->chunk.offset)++] : utext_next32(ut))

 /**

  * inline version of utext_previous32(), for performance-critical situations.

  *

  *  Move the iterator position to the character (code point) whose

  *  index precedes the current position, and return that character.

  *  This is a pre-decrement operation.

  *  Returns U_SENTINEL (-1) if the position is at the start of the  text.

  *

  * @draft ICU 3.4

  */

 #define UTEXT_PREVIOUS32(ut)  \

     ((ut)->chunk.offset > 0 && \

      (ut)->chunk.contents[(ut)->chunk.offset-1] < 0xd800 ? \

           (ut)->chunk.contents[--((ut)->chunk.offset)]  :  utext_previous32(ut))

 /************************************************************************************

  *

  *   Functions related to writing or modifying the text.

  *   These will work only with modifiable UTexts.  Attempting to

  *   modify a read-only UText will return an error status.

  *

  ************************************************************************************/

 /**

  *  Return TRUE if the text can be written with utext_replace() or

  *  utext_copy().  For the text to be writable, the text provider must

  *  be of a type that supports writing.

  *

  * @param  ut   the UText to be tested.

  * @return TRUE if the text is modifiable.

  * @draft ICU 3.4

  *

  */

 U_DRAFT UBool U_EXPORT2

 utext_isWritable(const UText *ut);

 /**

   * Test whether there is meta data associated with the text.

   * @see Replaceable::hasMetaData()

   *

   * @param ut The UText to be tested

   * @return TRUE if the underlying text includes meta data.

   * @draft ICU 3.4

   */

 U_DRAFT UBool U_EXPORT2

 utext_hasMetaData(const UText *ut);

 /**

  * Replace a range of the original text with a replacement text.

  *

  * Leaves the current iteration position at the position following the

  *  newly inserted replacement text.

  *

  * This function is only available on UText types that support writing,

  * that is, ones where utext_isWritable() returns TRUE.

  *

  * When using this function, there should be only a single UText opened onto the

  * underlying native text string.  Behavior after a replace operation

  * on a UText is undefined for any other additional UTexts that refer to the

  * modified string.

  *

  * @param ut               the UText representing the text to be operated on.

  * @param nativeStart      the native index of the start of the region to be replaced

  * @param nativeLimit      the native index of the character following the region to be replaced.

  * @param replacementText  pointer to the replacement text

  * @param replacementLength length of the replacement text, or -1 if the text is NUL terminated.

  * @param status           receives any error status.  Possible errors include

  *                         U_NO_WRITE_PERMISSION

  *

  * @return The signed number of (native) storage units by which

  *         the length of the text expanded or contracted.

  *

  * @draft ICU 3.4

  */

 U_DRAFT int32_t U_EXPORT2

 utext_replace(UText *ut,

              int32_t nativeStart, int32_t nativeLimit,

              const UChar *replacementText, int32_t replacementLength,

              UErrorCode *status);

 /**

  *

  * Copy or move a substring from one position to another within the text,

  * while retaining any metadata associated with the text.

  * This function is used to duplicate or reorder substrings.

  * The destination index must not overlap the source range.

  *

  * The text to be copied or moved is inserted at destIndex;

  * it does not replace or overwrite any existing text.

  *

  * This function is only available on UText types that support writing,

  * that is, ones where utext_isWritable() returns TRUE.

  *

  * When using this function, there should be only a single UText opened onto the

  * underlying native text string.  Behavior after a copy operation

  * on a UText is undefined in any other additional UTexts that refer to the

  * modified string.

  *

  * @param ut           The UText representing the text to be operated on.

  * @param nativeStart  The native index of the start of the region to be copied or moved

  * @param nativeLimit  The native index of the character position following the region to be copied.

  * @param destIndex    The native destination index to which the source substring is copied or moved.

  * @param move         If TRUE, then the substring is moved, not copied/duplicated.

  * @param status       receives any error status.  Possible errors include U_NO_WRITE_PERMISSION

  *                       

  * @draft ICU 3.4

  */

 U_DRAFT void U_EXPORT2

 utext_copy(UText *ut,

           int32_t nativeStart, int32_t nativeLimit,

           int32_t destIndex,

           UBool move,

           UErrorCode *status);

 /****************************************************************************************

  *

  *   The following items are required by text providers implementations -

  *    by packages that are writing UText wrappers for additional types of text strings.

  *    These declarations are not needed by applications that use already existing

  *    UText functions for wrapping strings or accessing text data that has been

  *    wrapped in a UText.

  *

  *****************************************************************************************/

 /**

   *  Descriptor of a chunk, or segment of text in UChar format.

   *

   *  UText provider implementations surface their text in the form of UTextChunks.

   *

   *  If the native form of the text if UTF-16, a chunk will typically refer back to the

   *   original native text storage.  If the native format is something else, chunks

   *   will typically refer to a buffer maintained by the provider that contains

   *   some amount input that has been converted to UTF-16 (UChar) form.

   *

   * @draft ICU 3.4

   */  

 struct UTextChunk {

     /** Pointer to contents of text chunk.  UChar format.   */

     const UChar *contents;

     /**  Index within the contents of the current iteration position. */

     int32_t     offset;  

     /** Number of UChars in the chunk. */

     int32_t     length;

     /** (Native) text index corresponding to the start of the chunk. */

     int32_t     nativeStart;

     /** (Native) text index corresponding to the end of the chunk (contents+length). */

     int32_t     nativeLimit;

     /** If TRUE, then non-UTF-16 indexes are used in this chunk. */

     UBool       nonUTF16Indexes;

     /** Unused. */

     UBool       padding1, padding2, padding3;

     /** Unused. */

     int32_t     padInt1, padInt2;

     /** Contains sizeof(UTextChunk) and allows the future addition of fields. */

     int32_t     sizeOfStruct;

 };

 /**

  * UText provider properties (bit field indexes).

  *

  * @see UText

  * @draft ICU 3.4

  */

 enum {

     /**

      * The provider works with non-UTF-16 ("native") text indexes.

      * For example, byte indexes into UTF-8 text or UTF-32 indexes into UTF-32 text.

      * @draft ICU 3.4

      */

     UTEXT_PROVIDER_NON_UTF16_INDEXES = 0,

     /**

      * It is potentially time consuming for the provider to determine the length of the text.

      * @draft ICU 3.4

      */

     UTEXT_PROVIDER_LENGTH_IS_EXPENSIVE = 1,

     /**

      * Text chunks remain valid and usable until the text object is modified or

      * deleted, not just until the next time the access() function is called

      * (which is the default).

      * @draft ICU 3.4

      */

     UTEXT_PROVIDER_STABLE_CHUNKS = 2,

     /**

      * The provider supports modifying the text via the replace() and copy()

      * functions.

      * @see Replaceable

      * @draft ICU 3.4

      */

     UTEXT_PROVIDER_WRITABLE = 3,

     /**

      * There is meta data associated with the text.

      * @see Replaceable::hasMetaData()

      * @draft ICU 3.4

      */

     UTEXT_PROVIDER_HAS_META_DATA = 4

 };

 /**

   * Function type declaration for UText.clone().

   *

   *  clone a UText.  Much like opening a UText where the source text is itself

   *  another UText.

   *

   *  A deep clone will copy both the UText data structures and the underlying text.

   *  The original and cloned UText will operate completely independently; modifications

   *  made to the text in one will not effect the other.  Text providers are not

   *  required to support deep clones.  The user of clone() must check the status return

   *  and be prepared to handle failures.

   *

   *  A shallow clone replicates only the UText data structures; it does not make

   *  a copy of the underlying text.  Shallow clones can be used as an efficient way to 

   *  have multiple iterators active in a single text string that is not being

   *  modified.

   *

   *  A shallow clone operation must not fail except for truly exceptional conditions such

   *  as memory allocation failures.

   *

   *  A UText and its clone may be safely concurrently accessed by separate threads.

   *  This is true for both shallow and deep clones.

   *  It is the responsibility of the Text Provider to ensure that this thread safety

   *  constraint is met.

   *

   *  @param dest   A UText struct to be filled in with the result of the clone operation,

   *                or NULL if the clone function should heap-allocate a new UText struct.

   *  @param src    The UText to be cloned.

   *  @param deep   TRUE to request a deep clone, FALSE for a shallow clone.

   *  @param status Errors are returned here.  For deep clones, U_UNSUPPORTED_ERROR

   *                should be returned if the text provider is unable to clone the

   *                original text.

   *  @return       The newly created clone, or NULL if the clone operation failed.

   *

   * @draft ICU 3.4

   */

 typedef UText * U_CALLCONV

 UTextClone(UText *dest, const UText *src, UBool deep, UErrorCode *status);

 /**

  * Function type declaration for UText.nativeLength().

  *

  * @param ut the UText to get the length of.

  * @return the length, in the native units of the original text string.

  * @see UText

  * @draft ICU 3.4

  */

 typedef int32_t U_CALLCONV

 UTextNativeLength(UText *ut);

 /**

  * Function type declaration for UText.access().  Get the description of the text chunk

  *  containing the text at a requested native index.  The UText's iteration

  *  position will be left at the requested index.  If the index is out

  *  of bounds, the iteration position will be left at the start or end

  *  of the string, as appropriate.

  *

  *  Chunks must begin and end on code point boundaries.  A single code point

  *  comprised of multiple storage units must never span a chunk boundary.

  *

  *

  * @param ut          the UText being accessed.

  * @param nativeIndex Requested index of the text to be accessed.

  * @param forward     If TRUE, then the returned chunk must contain text

  *                    starting from the index, so that start<=index<limit.

  *                    If FALSE, then the returned chunk must contain text

  *                    before the index, so that start<index<=limit.

  * @return            True if the requested index could be accessed.  The chunk

  *                    will contain the requested text.

  *                    False value if a chunk cannot be accessed

  *                    (the requested index is out of bounds).

  *

  * @see UText

  * @draft ICU 3.4

  */

 typedef UBool U_CALLCONV

 UTextAccess(UText *ut, int32_t nativeIndex, UBool forward, UTextChunk *chunk);

 /**

  * Function type declaration for UText.extract().

  *

  * Extract text from a UText into a UChar buffer.  The range of text to be extracted

  * is specified in the native indices of the UText provider.  These may not necessarily

  * be UTF-16 indices.

  * <p/>

  * The size (number of 16 bit UChars) in the data to be extracted is returned.  The

  * full amount is returned, even when the specified buffer size is smaller.

  *

  * The extracted string will (if you are a user) / must (if you are a text provider)

  * be NUL-terminated if there is sufficient space in the destination buffer.

  *

  * @param  ut            the UText from which to extract data.

  * @param  nativeStart   the native index of the first characer to extract.

  * @param  nativeLimit   the native string index of the position following the last

  *                       character to extract.

  * @param  dest          the UChar (UTF-16) buffer into which the extracted text is placed

  * @param  destCapacity  The size, in UChars, of the destination buffer.  May be zero

  *                       for precomputing the required size.

  * @param  status        receives any error status.

  *                       If U_BUFFER_OVERFLOW_ERROR: Returns number of UChars for

  *                       preflighting.

  * @return Number of UChars in the data.  Does not include a trailing NUL.

  *

  * @draft ICU 3.4

  */

 typedef int32_t U_CALLCONV

 UTextExtract(UText *ut,

              int32_t nativeStart, int32_t nativeLimit,

              UChar *dest, int32_t destCapacity,

              UErrorCode *status);

 /**

  * Function type declaration for UText.replace().

  *

  * Replace a range of the original text with a replacement text.

  *

  * Leaves the current iteration position at the position following the

  *  newly inserted replacement text.

  *

  * This function need only be implemented on UText types that support writing.

  *

  * When using this function, there should be only a single UText opened onto the

  * underlying native text string.  The function is responsible for updating the

  * text chunk within the UText to reflect the updated iteration position,

  * taking into account any changes to the underlying string's structure caused

  * by the replace operation.

  *

  * @param ut               the UText representing the text to be operated on.

  * @param nativeStart      the index of the start of the region to be replaced

  * @param nativeLimit      the index of the character following the region to be replaced.

  * @param replacementText  pointer to the replacement text

  * @param replacmentLength length of the replacement text in UChars, or -1 if the text is NUL terminated.

  * @param status           receives any error status.  Possible errors include

  *                         U_NO_WRITE_PERMISSION

  *

  * @return The signed number of (native) storage units by which

  *         the length of the text expanded or contracted.

  *

  * @draft ICU 3.4

  */

 typedef int32_t U_CALLCONV

 UTextReplace(UText *ut,

              int32_t nativeStart, int32_t nativeLimit,

              const UChar *replacementText, int32_t replacmentLength,

              UErrorCode *status);

 /**

  * Function type declaration for UText.copy().

  *

  * Copy or move a substring from one position to another within the text,

  * while retaining any metadata associated with the text.

  * This function is used to duplicate or reorder substrings.

  * The destination index must not overlap the source range.

  *

  * The text to be copied or moved is inserted at destIndex;

  * it does not replace or overwrite any existing text.

  *

  * This function need only be implemented for UText types that support writing.

  *

  * When using this function, there should be only a single UText opened onto the

  * underlying native text string.  The function is responsible for updating the

  * text chunk within the UText to reflect the updated iteration position,

  * taking into account any changes to the underlying string's structure caused

  * by the replace operation.

  *

  * @param ut           The UText representing the text to be operated on.

  * @param nativeStart  The index of the start of the region to be copied or moved

  * @param nativeLimit  The index of the character following the region to be replaced.

  * @param nativeDest   The destination index to which the source substring is copied or moved.

  * @param move         If TRUE, then the substring is moved, not copied/duplicated.

  * @param status       receives any error status.  Possible errors include U_NO_WRITE_PERMISSION

  *

  * @draft ICU 3.4

  */

 typedef void U_CALLCONV

 UTextCopy(UText *ut,

           int32_t nativeStart, int32_t nativeLimit,

           int32_t nativeDest,

           UBool move,

           UErrorCode *status);

 /**

  * Function type declaration for UText.mapOffsetToNative().

  * Map from a UChar offset within the current text chunk within the UText to

  *  the corresponding native index in the original source text.

  *

  * This is required only for text providers that do not use native UTF-16 indexes.

  *

  * TODO:  specify behavior with out-of-bounds offset?  Shouldn't ever occur.

  *

  * @param ut     the UText.

  * @param offset UTF-16 offset within text chunk 

  *               0<=offset<=chunk->length.

  * @return Absolute (native) index corresponding to the specified chunk offset.

  *         The returned native index should always be to a code point boundary.

  *

  * @draft ICU 3.4

  */

 typedef int32_t U_CALLCONV

 UTextMapOffsetToNative(UText *ut, int32_t offset);

 /**

  * Function type declaration for UText.mapIndexToUTF16().

  * Map from a native index to a UChar offset within a text chunk

  *

  * This function is required only for text providers that do not use native UTF-16 indexes.

  *

  * @param ut          The UText containing the text chunk.

  * @param nativeIndex Absolute (native) text index, chunk->start<=index<=chunk->limit.

  * @return            Chunk-relative UTF-16 offset corresponding to the specified native

  *                    index.

  *

  * TODO:  specify behavior with out-of-bounds index?  Shouldn't ever occur.

  * @draft ICU 3.4

  */

 typedef int32_t U_CALLCONV

 UTextMapNativeIndexToUTF16(UText *ut, int32_t nativeIndex);

 /**

  * Function type declaration for UText.utextClose().

  *

  * A Text Provider close function is only required for provider types that make

  *  allocations in their open function (or other functions) that must be 

  *  cleaned when the UText is closed.

  *

  * The allocation of the UText struct itself and any "extra" storage

  * associated with the UText is handled by the common UText implementation

  * and does not require provider specific cleanup in a close function.

  *

  * Most UText provider implementations do not need to implement this function.

  *

  * @param ut A UText object to be closed.

  *

  * @draft ICU 3.4

  */

 typedef void U_CALLCONV

 UTextClose(UText *ut);

 /**

   *   UText struct.  Provides the interface between the generic UText access code

   *                  and the UText provider code that works on specific kinds of

   *                  text  (UTF-8, noncontiguous UTF-16, whatever.)

   *

   *                  Applications that are using predefined types of text providers

   *                  to pass text data to ICU services will have no need to view the

   *                  internals of the UText structs that they open.

   *

   * @draft ICU 3.4

   */

 struct UText {

     /**

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

      * Not used by caller.

      * @draft ICU 3.4

      */

     const void *context;

     /**

      * (protected) Pointer fields available for use by the text provider.

      * Not used by UText common code.

      * @draft ICU 3.4

      */

     const void *p, *q, *r;

     /**

      *  (protected)  Pointer to additional space requested by the

      *               text provider during the utext_open operation.

      * @draft ICU 3.4

      */

     void          *pExtra;

     /**

      *   (protected)  Size in bytes of the extra space (pExtra).

      *  @draft ICU 3.4

      */

     int32_t        extraSize;

     /**

      *     (private)  Flags for managing the allocation and freeing of

      *                memory associated with this UText.

      * @internal

      */

     int32_t        flags;

     /**

      *     (private)  Magic.  Try to detect when we are handed junk.

      *                        utext_openXYZ() functions take an initialized,

      *                        but not necessarily open, UText struct as an,

      *                        optional fill-in parameter.  This magic field

      *                        is used to check for that initialization.

      *                        Text provider close functions must NOT clear

      *                        the magic field because that would prevent

      *                        reuse of the UText struct.

      * @internal

      */

     uint32_t       magic;

     /**

      * (public) sizeOfStruct=sizeof(UText)

      * Allows possible backward compatible extension.

      *

      * @draft ICU 3.4

      */

     int32_t         sizeOfStruct;

     /**

       * (protected) Integer fields for use by text provider.

       * Not used by caller.

       * @draft ICU 3.4

       */

     int32_t         a, b, c;

     /**

       *  Text provider properties.  This set of flags is maintainted by the

       *                             text provider implementation.

       *  @draft ICU 3.4

       */

     int32_t providerProperties;     

     /**  descriptor for the text chunk that includes or is adjacent to

       *  the current iteration position.

       *   @draft ICU 3.4

       */

     UTextChunk      chunk;   

     /**

      * (public) Function pointer for UTextClone

      *

      * @see UTextClone

      * @draft ICU 3.4

      */

     UTextClone *clone;

     /**

      * (public) function pointer for UTextLength

      * May be expensive to compute!

      *

      * @see UTextLength

      * @draft ICU 3.4

      */

     UTextNativeLength *nativeLength;

     /**

      * (public) Function pointer for UTextAccess.

      *

      * @see UTextAccess

      * @draft ICU 3.4

      */

     UTextAccess *access;

     /**

      * (public) Function pointer for UTextExtract.

      *

      * @see UTextExtract

      * @draft ICU 3.4

      */

     UTextExtract *extract;

     /**

      * (public) Function pointer for UTextReplace.

      *

      * @see UTextReplace

      * @draft ICU 3.4

      */

     UTextReplace *replace;

     /**

      * (public) Function pointer for UTextCopy.

      *

      * @see UTextCopy

      * @draft ICU 3.4

      */

     UTextCopy *copy;

     /**

      * (public) Function pointer for UTextMapOffsetToNative.

      *

      * @see UTextMapOffsetToNative

      * @draft ICU 3.4

      */

     UTextMapOffsetToNative *mapOffsetToNative;

     /**

      * (public) Function pointer for UTextMapNativeIndexToUTF16.

      *

      * @see UTextMapNativeIndexToUTF16

      * @draft ICU 3.4

      */

     UTextMapNativeIndexToUTF16 *mapNativeIndexToUTF16;

     /**

      * (public) Function pointer for UTextClose.

       *

       * @see UTextClose

       * @draft ICU 3.4

       */

     UTextClose  *close;

 };

 /**

  *  Common function for use by Text Provider implementations to allocate and/or initialize

  *  a new UText struct.  To be called in the implementation of utext_open() functions.

  *  If the supplied UText parameter is null, a new UText struct will be allocated on the heap.

  *  If the supplied UText is already open, the provider's close function will be called

  *  so that the struct can be reused by the open that is in progress.

  *

  * @param ut   pointer to a UText struct to be re-used, or null if a new UText

  *             should be allocated.

  * @param extraSpace The amount of additional space to be allocated as part

  *             of this UText, for use by types of providers that require

  *             additional storage.

  * @param status Errors are returned here.

  * @return pointer to the UText, allocated if necessary, with extra space set up if requested.

  * @draft ICU 3.4

  */

 U_DRAFT UText * U_EXPORT2

 utext_setup(UText *ut, int32_t extraSpace, UErrorCode *status);

 /**

   * @internal

   */

 enum {

     UTEXT_MAGIC = 0x345ad82c

 };

 /**

  *  Initializer for a UTextChunk

  *  @internal

  */

 #define UTEXT_CHUNK_INIT   {                               \

                   NULL,                /* contents      */ \

                   0,                   /* offset        */ \

                   0,                   /* length        */ \

                   0,                   /* start         */ \

                   0,                   /* limit         */ \

                   FALSE,               /* nonUTF16idx   */ \

                   FALSE, FALSE, FALSE, /* padding1,2,3  */ \

                   0, 0,                /* padInt1, 2    */ \

                   sizeof(UTextChunk)                       \

 }               

 /**

  * Initializer for the first part of a UText struct, the part that is

  *  in common for all types of text providers.

  *

  * @internal

  */

 #define UTEXT_INITIALIZER_HEAD  \

                   NULL,                 /* context       */ \

                   NULL, NULL, NULL,     /* p, q, r       */ \

                   NULL,                 /* pExtra        */ \

                   0,                    /* extraSize     */ \

                   0,                    /* flags         */ \

                   UTEXT_MAGIC,          /* magic         */ \

                   sizeof(UText),        /* sizeOfStruct  */ \

                   0, 0, 0,              /* a, b, c       */ \

                   0,                    /* providerProps */ \

                   UTEXT_CHUNK_INIT      /* UTextChunk    */

 /**

  * initializer to be used with local (stack) instances of a UText

  *  struct.  UText structs must be initialized before passing

  *  them to one of the utext_open functions.

  *

  * @draft ICU 3.4

  */

 #define UTEXT_INITIALIZER {                                \

                   UTEXT_INITIALIZER_HEAD,                  \

                   NULL,                 /* clone ()     */ \

                   NULL,                 /* length ()    */ \

                   NULL,                 /* access ()    */ \

                   NULL,                 /* extract ()   */ \

                   NULL,                 /* replace ()   */ \

                   NULL,                 /* copy ()      */ \

                   NULL, NULL,           /* map * 2 ()   */ \

                   NULL                  /* close ()     */ \

 }

 U_CDECL_END

 #endif /* U_HIDE_DRAFT_API */

 #endif