text: // © 2016 and later: Unicode, Inc. and others.
  // License & terms of use: http://www.unicode.org/copyright.html
  /*
  *******************************************************************************
  *
  *   Copyright (C) 2004-2012, International Business Machines
  *   Corporation and others.  All Rights Reserved.
  *
  *******************************************************************************
  *   file name:  utext.h
  *   encoding:   UTF-8
  *   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 in 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.
   *
   * <em>Conventions for calling UText functions</em>
   *
   * Most UText access functions have as their first parameter a (UText *) pointer,
   * which specifies the UText to be used.  Unless otherwise noted, the
   * pointer must refer to a valid, open UText.  Attempting to
   * use a closed UText or passing a NULL pointer is a programming error and
   * will produce undefined results or NULL pointer exceptions.
   * 
   * The UText_Open family of functions can either open an existing (closed)
   * UText, or heap allocate a new UText.  Here is sample code for creating
   * a stack-allocated UText.
   *
   * \code
   *    char     *s = whatever();  // A utf-8 string 
   *    U_ErrorCode status = U_ZERO_ERROR;
   *    UText    ut = UTEXT_INITIALIZER;
   *    utext_openUTF8(ut, s, -1, &status);
   *    if (U_FAILURE(status)) {
   *        // error handling
   *    } else {
   *        // work with the UText
   *    }
   * \endcode
   *
   * Any existing UText passed to an open function _must_ have been initialized, 
   * either by the UTEXT_INITIALIZER, or by having been originally heap-allocated
   * by an open function.  Passing NULL will cause the open function to
   * heap-allocate and fully initialize a new UText.
   *
   */
  
  
  
  #include "unicode/utypes.h"
  #include "unicode/uchar.h"
  #if U_SHOW_CPLUSPLUS_API
  #include "unicode/localpointer.h"
  #include "unicode/rep.h"
  #include "unicode/unistr.h"
  #include "unicode/chariter.h"
  #endif
  
  
  U_CDECL_BEGIN
  
  struct UText;
  typedef struct UText UText; /**< C typedef for struct UText. @stable ICU 3.6 */
  
  
  /***************************************************************************************
   *
   *   C Functions for creating UText wrappers around various kinds of text strings.
   *
   ****************************************************************************************/
  
  
  /**
    * 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.
    *
    * @stable ICU 3.4
    */
  U_STABLE UText * U_EXPORT2
  utext_close(UText *ut);
  
  #if U_SHOW_CPLUSPLUS_API
  
  U_NAMESPACE_BEGIN
  
  /**
   * \class LocalUTextPointer
   * "Smart pointer" class, closes a UText via utext_close().
   * For most methods see the LocalPointerBase base class.
   *
   * @see LocalPointerBase
   * @see LocalPointer
   * @stable ICU 4.4
   */
  U_DEFINE_LOCAL_OPEN_POINTER(LocalUTextPointer, UText, utext_close);
  
  U_NAMESPACE_END
  
  #endif
  
  /**
   * 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.  Must not be NULL.
   * @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.
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openUTF8(UText *ut, const char *s, int64_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.
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openUChars(UText *ut, const UChar *s, int64_t length, UErrorCode *status);
  
  
  #if U_SHOW_CPLUSPLUS_API
  /**
   * 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.
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openUnicodeString(UText *ut, icu::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.
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openConstUnicodeString(UText *ut, const icu::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
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openReplaceable(UText *ut, icu::Replaceable *rep, UErrorCode *status);
  
  /**
   * Open a  UText implementation over an ICU CharacterIterator.
   * @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 ci     A Character Iterator.
   * @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
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_openCharacterIterator(UText *ut, icu::CharacterIterator *ci, UErrorCode *status);
  
  #endif
  
  
  /**
    *  Clone a UText.  This is 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 affect 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.
    *
    *  The standard UText implementations for UTF8, UChar *, UnicodeString and
    *  Replaceable all support deep cloning.
    *
    *  The UText returned from a deep clone will be writable, assuming that the text
    *  provider is able to support writing, even if the source UText had been made
    *  non-writable by means of UText_freeze().
    *
    *  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.
    *
    *  Shallow UText clones should be avoided if the UText functions that modify the
    *  text are expected to be used, either on the original or the cloned UText.
    *  Any such modifications  can cause unpredictable behavior.  Read Only
    *  shallow clones provide some protection against errors of this type by
    *  disabling text modification via the cloned UText.
    *
    *  A shallow clone made with the readOnly parameter == FALSE will preserve the 
    *  utext_isWritable() state of the source object.  Note, however, that
    *  write operations must be avoided while more than one UText exists that refer
    *  to the same underlying text.
    *
    *  A UText and its clone may be safely concurrently accessed by separate threads.
    *  This is true for read access only with shallow clones, and for both read and
    *  write access with 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.
    *                If non-NULL, must refer to an already existing UText, which will then
    *                be reset to become the clone.
    *  @param src    The UText to be cloned.
    *  @param deep   TRUE to request a deep clone, FALSE for a shallow clone.
    *  @param readOnly TRUE to request that the cloned UText have read only access to the 
    *                underlying text.  
  
    *  @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.
    *  @stable ICU 3.4
    */
  U_STABLE UText * U_EXPORT2
  utext_clone(UText *dest, const UText *src, UBool deep, UBool readOnly, UErrorCode *status);
  
  
  /**
    *  Compare two UText objects for equality.
    *  UTexts are equal if they are iterating over the same text, and
    *    have the same iteration position within the text.
    *    If either or both of the parameters are NULL, the comparison is FALSE.
    *
    *  @param a   The first of the two UTexts to compare.
    *  @param b   The other UText to be compared.
    *  @return    TRUE if the two UTexts are equal.
    *  @stable ICU 3.6
    */
  U_STABLE UBool U_EXPORT2
  utext_equals(const UText *a, const UText *b);
  
  
  /*****************************************************************************
   *
   *   Functions to work with the text represented 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.
    *
    * @stable ICU 3.4
    */
  U_STABLE int64_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.
   * @stable ICU 3.4
   */
  U_STABLE 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 sequence
   *    utext_setNativeIndex(index);
   *    utext_current32();
   * (There is a subtle difference if the index is out of bounds by being less than zero - 
   * utext_setNativeIndex(negative value) sets the index to zero, after which utext_current()
   * will return the char at zero.  utext_char32At(negative index), on the other hand, will
   * return the U_SENTINEL value of -1.)
   * 
   * @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.
   * @stable ICU 3.4
   */
  U_STABLE UChar32 U_EXPORT2
  utext_char32At(UText *ut, int64_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.
   * @stable ICU 3.4
   */
  U_STABLE 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.
   *
   * If the position is at the end of the text (the index following
   * the last character, which is also the length of the text), 
   * return U_SENTINEL (-1) and do not advance the index. 
   *
   * 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
   * @stable ICU 3.4
   */
  U_STABLE 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.
   *
   *  If the initial position is at the start of the text (index of 0) 
   *  return U_SENTINEL (-1), and leave the position unchanged.
   *
   *  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
   *  @stable ICU 3.4
   */
  U_STABLE UChar32 U_EXPORT2
  utext_previous32(UText *ut);
  
  
  /**
    * Set the iteration index and return the code point at 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.  The results are identical to the those
    * from the sequence
    * \code
    *    utext_setIndex();
    *    utext_next32();
    * \endcode
    *
    *  @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.
    * @stable ICU 3.4
    */
  U_STABLE UChar32 U_EXPORT2
  utext_next32From(UText *ut, int64_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.
    *
    * @stable ICU 3.4
    */
  U_STABLE UChar32 U_EXPORT2
  utext_previous32From(UText *ut, int64_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 (possibly UTF-8 for example), and may not always be the same as
    * the corresponding UChar (UTF-16) index.
    * 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.
    * @stable ICU 3.4
    */
  U_STABLE int64_t U_EXPORT2
  utext_getNativeIndex(const 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 pinned 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.
   * @stable ICU 3.4
   */
  U_STABLE void U_EXPORT2
  utext_setNativeIndex(UText *ut, int64_t nativeIndex);
  
  /**
   * Move the iterator position 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.
   *
   * @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].
   * @stable ICU 3.4
   */
  U_STABLE UBool U_EXPORT2
  utext_moveIndex32(UText *ut, int32_t delta);
  
  /**
   * Get the native index of the character preceding the current position.
   * If the iteration position is already at the start of the text, zero
   * is returned.
   * The value returned is the same as that obtained from the following sequence,
   * but without the side effect of changing the iteration position.
   *   
   * \code
   *    UText  *ut = whatever;
   *      ...
   *    utext_previous(ut)
   *    utext_getNativeIndex(ut);
   * \endcode
   *
   * This function is most useful during forwards iteration, where it will get the
   *   native index of the character most recently returned from utext_next().
   *
   * @param ut the text to be accessed
   * @return the native index of the character preceding the current index position,
   *         or zero if the current position is at the start of the text.
   * @stable ICU 3.6
   */
  U_STABLE int64_t U_EXPORT2
  utext_getPreviousNativeIndex(UText *ut); 
  
  
  /**
   *
   * 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) of 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.
   * <p>
   * 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.
   * <p>
   * The iteration index is left at the position following the last extracted character.
   *
   * @param  ut    the UText from which to extract data.
   * @param  nativeStart the native index of the first character to extract.\
   *               If the specified index is out of range,
   *               it will be pinned to be within 0 <= index <= textLength
   * @param  nativeLimit the native string index of the position following the last
   *               character to extract.  If the specified index is out of range,
   *               it will be pinned to be within 0 <= index <= textLength.
   *               nativeLimit must be >= nativeStart.
   * @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.
   *
   * @stable ICU 3.4
   */
  U_STABLE int32_t U_EXPORT2
  utext_extract(UText *ut,
               int64_t nativeStart, int64_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.
   *
   ************************************************************************************/
  
  #ifndef U_HIDE_INTERNAL_API
  /**
   * inline version of utext_current32(), for performance-critical situations.
   *
   * Get the code point at the current iteration position of the UText.
   * Returns U_SENTINEL (-1) if the position is at the end of the
   * text.
   *
   * @internal ICU 4.4 technology preview
   */
  #define UTEXT_CURRENT32(ut)  \
      ((ut)->chunkOffset < (ut)->chunkLength && ((ut)->chunkContents)[(ut)->chunkOffset]<0xd800 ? \
      ((ut)->chunkContents)[((ut)->chunkOffset)] : utext_current32(ut))
  #endif  /* U_HIDE_INTERNAL_API */
  
  /**
   * 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.
   *
   * @stable ICU 3.4
   */
  #define UTEXT_NEXT32(ut)  \
      ((ut)->chunkOffset < (ut)->chunkLength && ((ut)->chunkContents)[(ut)->chunkOffset]<0xd800 ? \
      ((ut)->chunkContents)[((ut)->chunkOffset)++] : 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.
   *
   * @stable ICU 3.4
   */
  #define UTEXT_PREVIOUS32(ut)  \
      ((ut)->chunkOffset > 0 && \
       (ut)->chunkContents[(ut)->chunkOffset-1] < 0xd800 ? \
            (ut)->chunkContents[--((ut)->chunkOffset)]  :  utext_previous32(ut))
  
  /**
    *  inline version of utext_getNativeIndex(), for performance-critical situations.
    *
    * 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 (possibly UTF-8 for example), and may not always be the same as
    * the corresponding UChar (UTF-16) index.
    * The returned position will always be aligned to a code point boundary. 
    *
    * @stable ICU 3.6
    */
  #define UTEXT_GETNATIVEINDEX(ut)                       \
      ((ut)->chunkOffset <= (ut)->nativeIndexingLimit?   \
          (ut)->chunkNativeStart+(ut)->chunkOffset :     \
          (ut)->pFuncs->mapOffsetToNative(ut))    
  
  /**
    *  inline version of utext_setNativeIndex(), for performance-critical situations.
    *
    * 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 pinned to be within
    * the range of the input text.
    *
    * @stable ICU 3.8
    */
  #define UTEXT_SETNATIVEINDEX(ut, ix) UPRV_BLOCK_MACRO_BEGIN { \
      int64_t __offset = (ix) - (ut)->chunkNativeStart; \
      if (__offset>=0 && __offset<(int64_t)(ut)->nativeIndexingLimit && (ut)->chunkContents[__offset]<0xdc00) { \
          (ut)->chunkOffset=(int32_t)__offset; \
      } else { \
          utext_setNativeIndex((ut), (ix)); \
      } \
  } UPRV_BLOCK_MACRO_END
  
  
  
  /************************************************************************************
   *
   *   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 (modified) with utext_replace() or
   *  utext_copy().  For the text to be writable, the text provider must
   *  be of a type that supports writing and the UText must not be frozen.
   *
   *  Attempting to modify text when utext_isWriteable() is FALSE will fail -
   *  the text will not be modified, and an error will be returned from the function
   *  that attempted the modification.
   *
   * @param  ut   the UText to be tested.
   * @return TRUE if the text is modifiable.
   *
   * @see    utext_freeze()
   * @see    utext_replace()
   * @see    utext_copy()
   * @stable ICU 3.4
   *
   */
  U_STABLE 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.
    * @stable ICU 3.4
    */
  U_STABLE 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.
   *
   * @stable ICU 3.4
   */
  U_STABLE int32_t U_EXPORT2
  utext_replace(UText *ut,
               int64_t nativeStart, int64_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.
   *
   * The iteration position is left following the newly inserted text
   * at the destination position.
   *
   * 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
   *                       
   * @stable ICU 3.4
   */
  U_STABLE void U_EXPORT2
  utext_copy(UText *ut,
            int64_t nativeStart, int64_t nativeLimit,
            int64_t destIndex,
            UBool move,
            UErrorCode *status);
  
  
  /**
    *  <p>
    *  Freeze a UText.  This prevents any modification to the underlying text itself
    *  by means of functions operating on this UText.
    *  </p>
    *  <p>
    *  Once frozen, a UText can not be unfrozen.  The intent is to ensure
    *  that a the text underlying a frozen UText wrapper cannot be modified via that UText.
    *  </p>
    *  <p>
    *  Caution:  freezing a UText will disable changes made via the specific
    *   frozen UText wrapper only; it will not have any effect on the ability to
    *   directly modify the text by bypassing the UText.  Any such backdoor modifications
    *   are always an error while UText access is occurring because the underlying
    *   text can get out of sync with UText's buffering.
    *  </p>
    *
    *  @param ut  The UText to be frozen.
    *  @see   utext_isWritable()
    *  @stable ICU 3.6
    */
  U_STABLE void U_EXPORT2
  utext_freeze(UText *ut);
  
  
  /**
   * UText provider properties (bit field indexes).
   *
   * @see UText
   * @stable ICU 3.4
   */
  enum {
      /**
       * It is potentially time consuming for the provider to determine the length of the text.
       * @stable 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).
       * @stable ICU 3.4
       */
      UTEXT_PROVIDER_STABLE_CHUNKS = 2,
      /**
       * The provider supports modifying the text via the replace() and copy()
       * functions.
       * @see Replaceable
       * @stable ICU 3.4
       */
      UTEXT_PROVIDER_WRITABLE = 3,
      /**
       * There is meta data associated with the text.
       * @see Replaceable::hasMetaData()
       * @stable ICU 3.4
       */ 
      UTEXT_PROVIDER_HAS_META_DATA = 4,
      /**
       * Text provider owns the text storage.
       *  Generally occurs as the result of a deep clone of the UText.
       *  When closing the UText, the associated text must
       *  also be closed/deleted/freed/ whatever is appropriate.
       * @stable ICU 3.6
       */
       UTEXT_PROVIDER_OWNS_TEXT = 5
  };
  
  /**
    * 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.
    *
    * @stable 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
   * @stable ICU 3.4
   */
  typedef int64_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
   * @stable ICU 3.4
   */
  typedef UBool U_CALLCONV
  UTextAccess(UText *ut, int64_t nativeIndex, UBool forward);
  
  /**
   * 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.
   * <p>
   * 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 character 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.
   *
   * @stable ICU 3.4
   */
  typedef int32_t U_CALLCONV
  UTextExtract(UText *ut,
               int64_t nativeStart, int64_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.
   *
   * @stable ICU 3.4
   */
  typedef int32_t U_CALLCONV
  UTextReplace(UText *ut,
               int64_t nativeStart, int64_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
   *
   * @stable ICU 3.4
   */
  typedef void U_CALLCONV
  UTextCopy(UText *ut,
            int64_t nativeStart, int64_t nativeLimit,
            int64_t nativeDest,
            UBool move,
            UErrorCode *status);
  
  /**
   * Function type declaration for UText.mapOffsetToNative().
   * Map from the current UChar offset within the current text chunk 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.
   *
   * @param ut     the UText.
   * @return Absolute (native) index corresponding to chunkOffset in the current chunk.
   *         The returned native index should always be to a code point boundary.
   *
   * @stable ICU 3.4
   */
  typedef int64_t U_CALLCONV
  UTextMapOffsetToNative(const UText *ut);
  
  /**
   * Function type declaration for UText.mapIndexToUTF16().
   * Map from a native index to a UChar offset within a text chunk.
   * Behavior is undefined if the native index does not fall within the
   *   current 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.
   *
   * @stable ICU 3.4
   */
  typedef int32_t U_CALLCONV
  UTextMapNativeIndexToUTF16(const UText *ut, int64_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.
   *
   * @stable ICU 3.4
   */
  typedef void U_CALLCONV
  UTextClose(UText *ut);
  
  
  /**
    *   (public)  Function dispatch table for UText.
    *             Conceptually very much like a C++ Virtual Function Table.
    *             This struct defines the organization of the table.
    *             Each text provider implementation must provide an
    *              actual table that is initialized with the appropriate functions
    *              for the type of text being handled.
    *   @stable ICU 3.6
    */
  struct UTextFuncs {
      /**
       *   (public)  Function table size, sizeof(UTextFuncs)
       *             Intended for use should the table grow to accommodate added
       *             functions in the future, to allow tests for older format
       *             function tables that do not contain the extensions.
       *
       *             Fields are placed for optimal alignment on
       *             32/64/128-bit-pointer machines, by normally grouping together
       *             4 32-bit fields,
       *             4 pointers,
       *             2 64-bit fields
       *             in sequence.
       *   @stable ICU 3.6
       */
      int32_t       tableSize;
  
      /**
        *   (private)  Alignment padding.
        *              Do not use, reserved for use by the UText framework only.
        *   @internal
        */
      int32_t       reserved1, /** @internal */ reserved2, /** @internal */ reserved3;
  
  
      /**
       * (public) Function pointer for UTextClone
       *
       * @see UTextClone
       * @stable ICU 3.6
       */
      UTextClone *clone;
  
      /**
       * (public) function pointer for UTextLength
       * May be expensive to compute!
       *
       * @see UTextLength
       * @stable ICU 3.6
       */
      UTextNativeLength *nativeLength;
  
      /**
       * (public) Function pointer for UTextAccess.
       *
       * @see UTextAccess
       * @stable ICU 3.6
       */
      UTextAccess *access;
  
      /**
       * (public) Function pointer for UTextExtract.
       *
       * @see UTextExtract
       * @stable ICU 3.6
       */
      UTextExtract *extract;
  
      /**
       * (public) Function pointer for UTextReplace.
       *
       * @see UTextReplace
       * @stable ICU 3.6
       */
      UTextReplace *replace;
  
      /**
       * (public) Function pointer for UTextCopy.
       *
       * @see UTextCopy
       * @stable ICU 3.6
       */
      UTextCopy *copy;
  
      /**
       * (public) Function pointer for UTextMapOffsetToNative.
       *
       * @see UTextMapOffsetToNative
       * @stable ICU 3.6
       */
      UTextMapOffsetToNative *mapOffsetToNative;
  
      /**
       * (public) Function pointer for UTextMapNativeIndexToUTF16.
       *
       * @see UTextMapNativeIndexToUTF16
       * @stable ICU 3.6
       */
      UTextMapNativeIndexToUTF16 *mapNativeIndexToUTF16;
  
      /**
       * (public) Function pointer for UTextClose.
        *
        * @see UTextClose
        * @stable ICU 3.6
        */
      UTextClose  *close;
  
      /**
        * (private)  Spare function pointer
        * @internal
        */
      UTextClose  *spare1;
      
      /**
        * (private)  Spare function pointer
        * @internal
        */
      UTextClose  *spare2;
  
      /**
        * (private)  Spare function pointer
        * @internal
        */
      UTextClose  *spare3;
  
  };
  /**
   * Function dispatch table for UText
   * @see UTextFuncs
   */
  typedef struct UTextFuncs UTextFuncs;
  
   /**
    *   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.
    *
    * @stable ICU 3.6
    */
  struct UText {
      /**
       *     (private)  Magic.  Used to help detect when UText functions are handed
       *                        invalid or uninitialized UText structs.
       *                        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;
  
  
      /**
       *     (private)  Flags for managing the allocation and freeing of
       *                memory associated with this UText.
       * @internal
       */
      int32_t        flags;
  
  
      /**
        *  Text provider properties.  This set of flags is maintained by the
        *                             text provider implementation.
        *  @stable ICU 3.4
        */
      int32_t         providerProperties;
  
      /**
       * (public) sizeOfStruct=sizeof(UText)
       * Allows possible backward compatible extension.
       *
       * @stable ICU 3.4
       */
      int32_t         sizeOfStruct;
      
      /* ------ 16 byte alignment boundary -----------  */
      
  
      /**
        *  (protected) Native index of the first character position following
        *              the current chunk.
        *  @stable ICU 3.6
        */
      int64_t         chunkNativeLimit;
  
      /**
       *   (protected)  Size in bytes of the extra space (pExtra).
       *  @stable ICU 3.4
       */
      int32_t        extraSize;
  
      /**
        *    (protected) The highest chunk offset where native indexing and
        *    chunk (UTF-16) indexing correspond.  For UTF-16 sources, value
        *    will be equal to chunkLength.
        *
        *    @stable ICU 3.6
        */
      int32_t         nativeIndexingLimit;
  
      /* ---- 16 byte alignment boundary------ */
      
      /**
       *  (protected) Native index of the first character in the text chunk.
       *  @stable ICU 3.6
       */
      int64_t         chunkNativeStart;
  
      /**
       *  (protected) Current iteration position within the text chunk (UTF-16 buffer).
       *  This is the index to the character that will be returned by utext_next32().
       *  @stable ICU 3.6
       */
      int32_t         chunkOffset;
  
      /**
       *  (protected) Length the text chunk (UTF-16 buffer), in UChars.
       *  @stable ICU 3.6
       */
      int32_t         chunkLength;
  
      /* ---- 16  byte alignment boundary-- */
      
  
      /**
       *  (protected)  pointer to a chunk of text in UTF-16 format.
       *  May refer either to original storage of the source of the text, or
       *  if conversion was required, to a buffer owned by the UText.
       *  @stable ICU 3.6
       */
      const UChar    *chunkContents;
  
       /**
        * (public)     Pointer to Dispatch table for accessing functions for this UText.
        * @stable ICU 3.6
        */
      const UTextFuncs     *pFuncs;
  
      /**
       *  (protected)  Pointer to additional space requested by the
       *               text provider during the utext_open operation.
       * @stable ICU 3.4
       */
      void          *pExtra;
  
      /**
       * (protected) Pointer to string or text-containing object or similar.
       * This is the source of the text that this UText is wrapping, in a format
       *  that is known to the text provider functions.
       * @stable ICU 3.4
       */
      const void   *context;
  
      /* --- 16 byte alignment boundary--- */
  
      /**
       * (protected) Pointer fields available for use by the text provider.
       * Not used by UText common code.
       * @stable ICU 3.6
       */
      const void     *p; 
      /**
       * (protected) Pointer fields available for use by the text provider.
       * Not used by UText common code.
       * @stable ICU 3.6
       */
      const void     *q;
       /**
       * (protected) Pointer fields available for use by the text provider.
       * Not used by UText common code.
       * @stable ICU 3.6
        */
      const void     *r;
  
      /**
        *  Private field reserved for future use by the UText framework
        *     itself.  This is not to be touched by the text providers.
        * @internal ICU 3.4
        */
      void           *privP;
  
  
      /* --- 16 byte alignment boundary--- */
      
  
      /**
        * (protected) Integer field reserved for use by the text provider.
        * Not used by the UText framework, or by the client (user) of the UText.
        * @stable ICU 3.4
        */
      int64_t         a;
  
      /**
        * (protected) Integer field reserved for use by the text provider.
        * Not used by the UText framework, or by the client (user) of the UText.
        * @stable ICU 3.4
        */
      int32_t         b;
  
      /**
        * (protected) Integer field reserved for use by the text provider.
        * Not used by the UText framework, or by the client (user) of the UText.
        * @stable ICU 3.4
        */
      int32_t         c;
  
      /*  ---- 16 byte alignment boundary---- */
  
  
      /**
        *  Private field reserved for future use by the UText framework
        *     itself.  This is not to be touched by the text providers.
        * @internal ICU 3.4
        */
      int64_t         privA;
      /**
        *  Private field reserved for future use by the UText framework
        *     itself.  This is not to be touched by the text providers.
        * @internal ICU 3.4
        */
      int32_t         privB;
      /**
        *  Private field reserved for future use by the UText framework
        *     itself.  This is not to be touched by the text providers.
        * @internal ICU 3.4
        */
      int32_t         privC;
  };
  
  
  /**
   *  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.
   * @stable ICU 3.4
   */
  U_STABLE UText * U_EXPORT2
  utext_setup(UText *ut, int32_t extraSpace, UErrorCode *status);
  
  // do not use #ifndef U_HIDE_INTERNAL_API around the following!
  /**
    * @internal
    *  Value used to help identify correctly initialized UText structs.
    *  Note:  must be publicly visible so that UTEXT_INITIALIZER can access it.
    */
  enum {
      UTEXT_MAGIC = 0x345ad82c
  };
  
  /**
   * 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.
   *
   * @stable ICU 3.6
   */
  #define UTEXT_INITIALIZER {                                        \
                    UTEXT_MAGIC,          /* magic                */ \
                    0,                    /* flags                */ \
                    0,                    /* providerProps        */ \
                    sizeof(UText),        /* sizeOfStruct         */ \
                    0,                    /* chunkNativeLimit     */ \
                    0,                    /* extraSize            */ \
                    0,                    /* nativeIndexingLimit  */ \
                    0,                    /* chunkNativeStart     */ \
                    0,                    /* chunkOffset          */ \
                    0,                    /* chunkLength          */ \
                    NULL,                 /* chunkContents        */ \
                    NULL,                 /* pFuncs               */ \
                    NULL,                 /* pExtra               */ \
                    NULL,                 /* context              */ \
                    NULL, NULL, NULL,     /* p, q, r              */ \
                    NULL,                 /* privP                */ \
                    0, 0, 0,              /* a, b, c              */ \
                    0, 0, 0               /* privA,B,C,           */ \
                    }
  
  
  U_CDECL_END
  
  
  
  #endif
  