text: // © 2016 and later: Unicode, Inc. and others.
  // License & terms of use: http://www.unicode.org/copyright.html
  /*
  ******************************************************************************
  *
  *   Copyright (C) 2001-2014, International Business Machines
  *   Corporation and others.  All Rights Reserved.
  *
  ******************************************************************************
  *   file name:  utrie2.h
  *   encoding:   UTF-8
  *   tab size:   8 (not used)
  *   indentation:4
  *
  *   created on: 2008aug16 (starting from a copy of utrie.h)
  *   created by: Markus W. Scherer
  */
  
  #ifndef __UTRIE2_H__
  #define __UTRIE2_H__
  
  #include "unicode/utypes.h"
  #include "unicode/utf8.h"
  #include "putilimp.h"
  
  U_CDECL_BEGIN
  
  struct UTrie;  /* forward declaration */
  #ifndef __UTRIE_H__
  typedef struct UTrie UTrie;
  #endif
  
  /**
   * \file
   *
   * This is a common implementation of a Unicode trie.
   * It is a kind of compressed, serializable table of 16- or 32-bit values associated with
   * Unicode code points (0..0x10ffff). (A map from code points to integers.)
   *
   * This is the second common version of a Unicode trie (hence the name UTrie2).
   * Compared with UTrie version 1:
   * - Still splitting BMP code points 11:5 bits for index and data table lookups.
   * - Still separate data for lead surrogate code _units_ vs. code _points_,
   *   but the lead surrogate code unit values are not required any more
   *   for data lookup for supplementary code points.
   * - The "folding" mechanism is removed. In UTrie version 1, this somewhat
   *   hard-to-explain mechanism was meant to be used for optimized UTF-16
   *   processing, with application-specific encoding of indexing bits
   *   in the lead surrogate data for the associated supplementary code points.
   * - For the last single-value code point range (ending with U+10ffff),
   *   the starting code point ("highStart") and the value are stored.
   * - For supplementary code points U+10000..highStart-1 a three-table lookup
   *   (two index tables and one data table) is used. The first index
   *   is truncated, omitting both the BMP portion and the high range.
   * - There is a special small index for 2-byte UTF-8, and the initial data
   *   entries are designed for fast 1/2-byte UTF-8 lookup.
   *   Starting with ICU 60, C0 and C1 are not recognized as UTF-8 lead bytes any more at all,
   *   and the associated 2-byte indexes are unused.
   */
  
  /**
   * Trie structure.
   * Use only with public API macros and functions.
   */
  struct UTrie2;
  typedef struct UTrie2 UTrie2;
  
  /* Public UTrie2 API functions: read-only access ---------------------------- */
  
  /**
   * Selectors for the width of a UTrie2 data value.
   */
  enum UTrie2ValueBits {
      /** 16 bits per UTrie2 data value. */
      UTRIE2_16_VALUE_BITS,
      /** 32 bits per UTrie2 data value. */
      UTRIE2_32_VALUE_BITS,
      /** Number of selectors for the width of UTrie2 data values. */
      UTRIE2_COUNT_VALUE_BITS
  };
  typedef enum UTrie2ValueBits UTrie2ValueBits;
  
  /**
   * Open a frozen trie from its serialized from, stored in 32-bit-aligned memory.
   * Inverse of utrie2_serialize().
   * The memory must remain valid and unchanged as long as the trie is used.
   * You must utrie2_close() the trie once you are done using it.
   *
   * @param valueBits selects the data entry size; results in an
   *                  U_INVALID_FORMAT_ERROR if it does not match the serialized form
   * @param data a pointer to 32-bit-aligned memory containing the serialized form of a UTrie2
   * @param length the number of bytes available at data;
   *               can be more than necessary
   * @param pActualLength receives the actual number of bytes at data taken up by the trie data;
   *                      can be NULL
   * @param pErrorCode an in/out ICU UErrorCode
   * @return the unserialized trie
   *
   * @see utrie2_open
   * @see utrie2_serialize
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_openFromSerialized(UTrie2ValueBits valueBits,
                            const void *data, int32_t length, int32_t *pActualLength,
                            UErrorCode *pErrorCode);
  
  /**
   * Open a frozen, empty "dummy" trie.
   * A dummy trie is an empty trie, used when a real data trie cannot
   * be loaded. Equivalent to calling utrie2_open() and utrie2_freeze(),
   * but without internally creating and compacting/serializing the
   * builder data structure.
   *
   * The trie always returns the initialValue,
   * or the errorValue for out-of-range code points and illegal UTF-8.
   *
   * You must utrie2_close() the trie once you are done using it.
   *
   * @param valueBits selects the data entry size
   * @param initialValue the initial value that is set for all code points
   * @param errorValue the value for out-of-range code points and illegal UTF-8
   * @param pErrorCode an in/out ICU UErrorCode
   * @return the dummy trie
   *
   * @see utrie2_openFromSerialized
   * @see utrie2_open
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_openDummy(UTrie2ValueBits valueBits,
                   uint32_t initialValue, uint32_t errorValue,
                   UErrorCode *pErrorCode);
  
  /**
   * Get a value from a code point as stored in the trie.
   * Easier to use than UTRIE2_GET16() and UTRIE2_GET32() but slower.
   * Easier to use because, unlike the macros, this function works on all UTrie2
   * objects, frozen or not, holding 16-bit or 32-bit data values.
   *
   * @param trie the trie
   * @param c the code point
   * @return the value
   */
  U_CAPI uint32_t U_EXPORT2
  utrie2_get32(const UTrie2 *trie, UChar32 c);
  
  /* enumeration callback types */
  
  /**
   * Callback from utrie2_enum(), extracts a uint32_t value from a
   * trie value. This value will be passed on to the UTrie2EnumRange function.
   *
   * @param context an opaque pointer, as passed into utrie2_enum()
   * @param value a value from the trie
   * @return the value that is to be passed on to the UTrie2EnumRange function
   */
  typedef uint32_t U_CALLCONV
  UTrie2EnumValue(const void *context, uint32_t value);
  
  /**
   * Callback from utrie2_enum(), is called for each contiguous range
   * of code points with the same value as retrieved from the trie and
   * transformed by the UTrie2EnumValue function.
   *
   * The callback function can stop the enumeration by returning false.
   *
   * @param context an opaque pointer, as passed into utrie2_enum()
   * @param start the first code point in a contiguous range with value
   * @param end the last code point in a contiguous range with value (inclusive)
   * @param value the value that is set for all code points in [start..end]
   * @return false to stop the enumeration
   */
  typedef UBool U_CALLCONV
  UTrie2EnumRange(const void *context, UChar32 start, UChar32 end, uint32_t value);
  
  /**
   * Enumerate efficiently all values in a trie.
   * Do not modify the trie during the enumeration.
   *
   * For each entry in the trie, the value to be delivered is passed through
   * the UTrie2EnumValue function.
   * The value is unchanged if that function pointer is NULL.
   *
   * For each contiguous range of code points with a given (transformed) value,
   * the UTrie2EnumRange function is called.
   *
   * @param trie a pointer to the trie
   * @param enumValue a pointer to a function that may transform the trie entry value,
   *                  or NULL if the values from the trie are to be used directly
   * @param enumRange a pointer to a function that is called for each contiguous range
   *                  of code points with the same (transformed) value
   * @param context an opaque pointer that is passed on to the callback functions
   */
  U_CAPI void U_EXPORT2
  utrie2_enum(const UTrie2 *trie,
              UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange, const void *context);
  
  /* Building a trie ---------------------------------------------------------- */
  
  /**
   * Open an empty, writable trie. At build time, 32-bit data values are used.
   * utrie2_freeze() takes a valueBits parameter
   * which determines the data value width in the serialized and frozen forms.
   * You must utrie2_close() the trie once you are done using it.
   *
   * @param initialValue the initial value that is set for all code points
   * @param errorValue the value for out-of-range code points and illegal UTF-8
   * @param pErrorCode an in/out ICU UErrorCode
   * @return a pointer to the allocated and initialized new trie
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_open(uint32_t initialValue, uint32_t errorValue, UErrorCode *pErrorCode);
  
  /**
   * Clone a trie.
   * You must utrie2_close() the clone once you are done using it.
   *
   * @param other the trie to clone
   * @param pErrorCode an in/out ICU UErrorCode
   * @return a pointer to the new trie clone
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_clone(const UTrie2 *other, UErrorCode *pErrorCode);
  
  /**
   * Clone a trie. The clone will be mutable/writable even if the other trie
   * is frozen. (See utrie2_freeze().)
   * You must utrie2_close() the clone once you are done using it.
   *
   * @param other the trie to clone
   * @param pErrorCode an in/out ICU UErrorCode
   * @return a pointer to the new trie clone
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_cloneAsThawed(const UTrie2 *other, UErrorCode *pErrorCode);
  
  /**
   * Close a trie and release associated memory.
   *
   * @param trie the trie
   */
  U_CAPI void U_EXPORT2
  utrie2_close(UTrie2 *trie);
  
  /**
   * Set a value for a code point.
   *
   * @param trie the unfrozen trie
   * @param c the code point
   * @param value the value
   * @param pErrorCode an in/out ICU UErrorCode; among other possible error codes:
   * - U_NO_WRITE_PERMISSION if the trie is frozen
   */
  U_CAPI void U_EXPORT2
  utrie2_set32(UTrie2 *trie, UChar32 c, uint32_t value, UErrorCode *pErrorCode);
  
  /**
   * Set a value in a range of code points [start..end].
   * All code points c with start<=c<=end will get the value if
   * overwrite is true or if the old value is the initial value.
   *
   * @param trie the unfrozen trie
   * @param start the first code point to get the value
   * @param end the last code point to get the value (inclusive)
   * @param value the value
   * @param overwrite flag for whether old non-initial values are to be overwritten
   * @param pErrorCode an in/out ICU UErrorCode; among other possible error codes:
   * - U_NO_WRITE_PERMISSION if the trie is frozen
   */
  U_CAPI void U_EXPORT2
  utrie2_setRange32(UTrie2 *trie,
                    UChar32 start, UChar32 end,
                    uint32_t value, UBool overwrite,
                    UErrorCode *pErrorCode);
  
  /**
   * Freeze a trie. Make it immutable (read-only) and compact it,
   * ready for serialization and for use with fast macros.
   * Functions to set values will fail after serializing.
   *
   * A trie can be frozen only once. If this function is called again with different
   * valueBits then it will set a U_ILLEGAL_ARGUMENT_ERROR.
   *
   * @param trie the trie
   * @param valueBits selects the data entry size; if smaller than 32 bits, then
   *                  the values stored in the trie will be truncated
   * @param pErrorCode an in/out ICU UErrorCode; among other possible error codes:
   * - U_INDEX_OUTOFBOUNDS_ERROR if the compacted index or data arrays are too long
   *                             for serialization
   *                             (the trie will be immutable and usable,
   *                             but not frozen and not usable with the fast macros)
   *
   * @see utrie2_cloneAsThawed
   */
  U_CAPI void U_EXPORT2
  utrie2_freeze(UTrie2 *trie, UTrie2ValueBits valueBits, UErrorCode *pErrorCode);
  
  /**
   * Test if the trie is frozen. (See utrie2_freeze().)
   *
   * @param trie the trie
   * @return true if the trie is frozen, that is, immutable, ready for serialization
   *         and for use with fast macros
   */
  U_CAPI UBool U_EXPORT2
  utrie2_isFrozen(const UTrie2 *trie);
  
  /**
   * Serialize a frozen trie into 32-bit aligned memory.
   * If the trie is not frozen, then the function returns with a U_ILLEGAL_ARGUMENT_ERROR.
   * A trie can be serialized multiple times.
   *
   * @param trie the frozen trie
   * @param data a pointer to 32-bit-aligned memory to be filled with the trie data,
   *             can be NULL if capacity==0
   * @param capacity the number of bytes available at data,
   *                 or 0 for preflighting
   * @param pErrorCode an in/out ICU UErrorCode; among other possible error codes:
   * - U_BUFFER_OVERFLOW_ERROR if the data storage block is too small for serialization
   * - U_ILLEGAL_ARGUMENT_ERROR if the trie is not frozen or the data and capacity
   *                            parameters are bad
   * @return the number of bytes written or needed for the trie
   *
   * @see utrie2_openFromSerialized()
   */
  U_CAPI int32_t U_EXPORT2
  utrie2_serialize(const UTrie2 *trie,
                   void *data, int32_t capacity,
                   UErrorCode *pErrorCode);
  
  /* Public UTrie2 API: miscellaneous functions ------------------------------- */
  
  /**
   * Build a UTrie2 (version 2) from a UTrie (version 1).
   * Enumerates all values in the UTrie and builds a UTrie2 with the same values.
   * The resulting UTrie2 will be frozen.
   *
   * @param trie1 the runtime UTrie structure to be enumerated
   * @param errorValue the value for out-of-range code points and illegal UTF-8
   * @param pErrorCode an in/out ICU UErrorCode
   * @return The frozen UTrie2 with the same values as the UTrie.
   */
  U_CAPI UTrie2 * U_EXPORT2
  utrie2_fromUTrie(const UTrie *trie1, uint32_t errorValue, UErrorCode *pErrorCode);
  
  /* Public UTrie2 API macros ------------------------------------------------- */
  
  /*
   * These macros provide fast data lookup from a frozen trie.
   * They will crash when used on an unfrozen trie.
   */
  
  /**
   * Return a 16-bit trie value from a code point, with range checking.
   * Returns trie->errorValue if c is not in the range 0..U+10ffff.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code point
   * @return (uint16_t) The code point's trie value.
   */
  #define UTRIE2_GET16(trie, c) _UTRIE2_GET((trie), index, (trie)->indexLength, (c))
  
  /**
   * Return a 32-bit trie value from a code point, with range checking.
   * Returns trie->errorValue if c is not in the range 0..U+10ffff.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code point
   * @return (uint32_t) The code point's trie value.
   */
  #define UTRIE2_GET32(trie, c) _UTRIE2_GET((trie), data32, 0, (c))
  
  /**
   * UTF-16: Get the next code point (UChar32 c, out), post-increment src,
   * and get a 16-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param src (const UChar *, in/out) the source text pointer
   * @param limit (const UChar *, in) the limit pointer for the text, or NULL if NUL-terminated
   * @param c (UChar32, out) variable for the code point
   * @param result (uint16_t, out) uint16_t variable for the trie lookup result
   */
  #define UTRIE2_U16_NEXT16(trie, src, limit, c, result) _UTRIE2_U16_NEXT(trie, index, src, limit, c, result)
  
  /**
   * UTF-16: Get the next code point (UChar32 c, out), post-increment src,
   * and get a 32-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param src (const UChar *, in/out) the source text pointer
   * @param limit (const UChar *, in) the limit pointer for the text, or NULL if NUL-terminated
   * @param c (UChar32, out) variable for the code point
   * @param result (uint32_t, out) uint32_t variable for the trie lookup result
   */
  #define UTRIE2_U16_NEXT32(trie, src, limit, c, result) _UTRIE2_U16_NEXT(trie, data32, src, limit, c, result)
  
  /**
   * UTF-16: Get the previous code point (UChar32 c, out), pre-decrement src,
   * and get a 16-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param start (const UChar *, in) the start pointer for the text
   * @param src (const UChar *, in/out) the source text pointer
   * @param c (UChar32, out) variable for the code point
   * @param result (uint16_t, out) uint16_t variable for the trie lookup result
   */
  #define UTRIE2_U16_PREV16(trie, start, src, c, result) _UTRIE2_U16_PREV(trie, index, start, src, c, result)
  
  /**
   * UTF-16: Get the previous code point (UChar32 c, out), pre-decrement src,
   * and get a 32-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param start (const UChar *, in) the start pointer for the text
   * @param src (const UChar *, in/out) the source text pointer
   * @param c (UChar32, out) variable for the code point
   * @param result (uint32_t, out) uint32_t variable for the trie lookup result
   */
  #define UTRIE2_U16_PREV32(trie, start, src, c, result) _UTRIE2_U16_PREV(trie, data32, start, src, c, result)
  
  /**
   * UTF-8: Post-increment src and get a 16-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param src (const char *, in/out) the source text pointer
   * @param limit (const char *, in) the limit pointer for the text (must not be NULL)
   * @param result (uint16_t, out) uint16_t variable for the trie lookup result
   */
  #define UTRIE2_U8_NEXT16(trie, src, limit, result)\
      _UTRIE2_U8_NEXT(trie, data16, index, src, limit, result)
  
  /**
   * UTF-8: Post-increment src and get a 32-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param src (const char *, in/out) the source text pointer
   * @param limit (const char *, in) the limit pointer for the text (must not be NULL)
   * @param result (uint16_t, out) uint32_t variable for the trie lookup result
   */
  #define UTRIE2_U8_NEXT32(trie, src, limit, result) \
      _UTRIE2_U8_NEXT(trie, data32, data32, src, limit, result)
  
  /**
   * UTF-8: Pre-decrement src and get a 16-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param start (const char *, in) the start pointer for the text
   * @param src (const char *, in/out) the source text pointer
   * @param result (uint16_t, out) uint16_t variable for the trie lookup result
   */
  #define UTRIE2_U8_PREV16(trie, start, src, result) \
      _UTRIE2_U8_PREV(trie, data16, index, start, src, result)
  
  /**
   * UTF-8: Pre-decrement src and get a 32-bit value from the trie.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param start (const char *, in) the start pointer for the text
   * @param src (const char *, in/out) the source text pointer
   * @param result (uint16_t, out) uint32_t variable for the trie lookup result
   */
  #define UTRIE2_U8_PREV32(trie, start, src, result) \
      _UTRIE2_U8_PREV(trie, data32, data32, start, src, result)
  
  /* Public UTrie2 API: optimized UTF-16 access ------------------------------- */
  
  /*
   * The following functions and macros are used for highly optimized UTF-16
   * text processing. The UTRIE2_U16_NEXTxy() macros do not depend on these.
   *
   * A UTrie2 stores separate values for lead surrogate code _units_ vs. code _points_.
   * UTF-16 text processing can be optimized by detecting surrogate pairs and
   * assembling supplementary code points only when there is non-trivial data
   * available.
   *
   * At build-time, use utrie2_enumForLeadSurrogate() to see if there
   * is non-trivial (non-initialValue) data for any of the supplementary
   * code points associated with a lead surrogate.
   * If so, then set a special (application-specific) value for the
   * lead surrogate code _unit_, with utrie2_set32ForLeadSurrogateCodeUnit().
   *
   * At runtime, use UTRIE2_GET16_FROM_U16_SINGLE_LEAD() or
   * UTRIE2_GET32_FROM_U16_SINGLE_LEAD() per code unit. If there is non-trivial
   * data and the code unit is a lead surrogate, then check if a trail surrogate
   * follows. If so, assemble the supplementary code point with
   * U16_GET_SUPPLEMENTARY() and look up its value with UTRIE2_GET16_FROM_SUPP()
   * or UTRIE2_GET32_FROM_SUPP(); otherwise reset the lead
   * surrogate's value or do a code point lookup for it.
   *
   * If there is only trivial data for lead and trail surrogates, then processing
   * can often skip them. For example, in normalization or case mapping
   * all characters that do not have any mappings are simply copied as is.
   */
  
  /**
   * Get a value from a lead surrogate code unit as stored in the trie.
   *
   * @param trie the trie
   * @param c the code unit (U+D800..U+DBFF)
   * @return the value
   */
  U_CAPI uint32_t U_EXPORT2
  utrie2_get32FromLeadSurrogateCodeUnit(const UTrie2 *trie, UChar32 c);
  
  /**
   * Enumerate the trie values for the 1024=0x400 code points
   * corresponding to a given lead surrogate.
   * For example, for the lead surrogate U+D87E it will enumerate the values
   * for [U+2F800..U+2FC00[.
   * Used by data builder code that sets special lead surrogate code unit values
   * for optimized UTF-16 string processing.
   *
   * Do not modify the trie during the enumeration.
   *
   * Except for the limited code point range, this functions just like utrie2_enum():
   * For each entry in the trie, the value to be delivered is passed through
   * the UTrie2EnumValue function.
   * The value is unchanged if that function pointer is NULL.
   *
   * For each contiguous range of code points with a given (transformed) value,
   * the UTrie2EnumRange function is called.
   *
   * @param trie a pointer to the trie
   * @param enumValue a pointer to a function that may transform the trie entry value,
   *                  or NULL if the values from the trie are to be used directly
   * @param enumRange a pointer to a function that is called for each contiguous range
   *                  of code points with the same (transformed) value
   * @param context an opaque pointer that is passed on to the callback functions
   */
  U_CAPI void U_EXPORT2
  utrie2_enumForLeadSurrogate(const UTrie2 *trie, UChar32 lead,
                              UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange,
                              const void *context);
  
  /**
   * Set a value for a lead surrogate code unit.
   *
   * @param trie the unfrozen trie
   * @param lead the lead surrogate code unit (U+D800..U+DBFF)
   * @param value the value
   * @param pErrorCode an in/out ICU UErrorCode; among other possible error codes:
   * - U_NO_WRITE_PERMISSION if the trie is frozen
   */
  U_CAPI void U_EXPORT2
  utrie2_set32ForLeadSurrogateCodeUnit(UTrie2 *trie,
                                       UChar32 lead, uint32_t value,
                                       UErrorCode *pErrorCode);
  
  /**
   * Return a 16-bit trie value from a UTF-16 single/lead code unit (<=U+ffff).
   * Same as UTRIE2_GET16() if c is a BMP code point except for lead surrogates,
   * but smaller and faster.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code unit, must be 0<=c<=U+ffff
   * @return (uint16_t) The code unit's trie value.
   */
  #define UTRIE2_GET16_FROM_U16_SINGLE_LEAD(trie, c) _UTRIE2_GET_FROM_U16_SINGLE_LEAD((trie), index, c)
  
  /**
   * Return a 32-bit trie value from a UTF-16 single/lead code unit (<=U+ffff).
   * Same as UTRIE2_GET32() if c is a BMP code point except for lead surrogates,
   * but smaller and faster.
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code unit, must be 0<=c<=U+ffff
   * @return (uint32_t) The code unit's trie value.
   */
  #define UTRIE2_GET32_FROM_U16_SINGLE_LEAD(trie, c) _UTRIE2_GET_FROM_U16_SINGLE_LEAD((trie), data32, c)
  
  /**
   * Return a 16-bit trie value from a supplementary code point (U+10000..U+10ffff).
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code point, must be U+10000<=c<=U+10ffff
   * @return (uint16_t) The code point's trie value.
   */
  #define UTRIE2_GET16_FROM_SUPP(trie, c) _UTRIE2_GET_FROM_SUPP((trie), index, c)
  
  /**
   * Return a 32-bit trie value from a supplementary code point (U+10000..U+10ffff).
   *
   * @param trie (const UTrie2 *, in) a frozen trie
   * @param c (UChar32, in) the input code point, must be U+10000<=c<=U+10ffff
   * @return (uint32_t) The code point's trie value.
   */
  #define UTRIE2_GET32_FROM_SUPP(trie, c) _UTRIE2_GET_FROM_SUPP((trie), data32, c)
  
  U_CDECL_END
  
  /* C++ convenience wrappers ------------------------------------------------- */
  
  #ifdef __cplusplus
  
  #include "unicode/utf.h"
  #include "mutex.h"
  
  U_NAMESPACE_BEGIN
  
  // Use the Forward/Backward subclasses below.
  class UTrie2StringIterator : public UMemory {
  public:
      UTrie2StringIterator(const UTrie2 *t, const UChar *p) :
          trie(t), codePointStart(p), codePointLimit(p), codePoint(U_SENTINEL) {}
  
      const UTrie2 *trie;
      const UChar *codePointStart, *codePointLimit;
      UChar32 codePoint;
  };
  
  class BackwardUTrie2StringIterator : public UTrie2StringIterator {
  public:
      BackwardUTrie2StringIterator(const UTrie2 *t, const UChar *s, const UChar *p) :
          UTrie2StringIterator(t, p), start(s) {}
  
      uint16_t previous16();
  
      const UChar *start;
  };
  
  class ForwardUTrie2StringIterator : public UTrie2StringIterator {
  public:
      // Iteration limit l can be NULL.
      // In that case, the caller must detect c==0 and stop.
      ForwardUTrie2StringIterator(const UTrie2 *t, const UChar *p, const UChar *l) :
          UTrie2StringIterator(t, p), limit(l) {}
  
      uint16_t next16();
  
      const UChar *limit;
  };
  
  U_NAMESPACE_END
  
  #endif
  
  /* Internal definitions ----------------------------------------------------- */
  
  U_CDECL_BEGIN
  
  /** Build-time trie structure. */
  struct UNewTrie2;
  typedef struct UNewTrie2 UNewTrie2;
  
  /*
   * Trie structure definition.
   *
   * Either the data table is 16 bits wide and accessed via the index
   * pointer, with each index item increased by indexLength;
   * in this case, data32==NULL, and data16 is used for direct ASCII access.
   *
   * Or the data table is 32 bits wide and accessed via the data32 pointer.
   */
  struct UTrie2 {
      /* protected: used by macros and functions for reading values */
      const uint16_t *index;
      const uint16_t *data16;     /* for fast UTF-8 ASCII access, if 16b data */
      const uint32_t *data32;     /* NULL if 16b data is used via index */
  
      int32_t indexLength, dataLength;
      uint16_t index2NullOffset;  /* 0xffff if there is no dedicated index-2 null block */
      uint16_t dataNullOffset;
      uint32_t initialValue;
      /** Value returned for out-of-range code points and illegal UTF-8. */
      uint32_t errorValue;
  
      /* Start of the last range which ends at U+10ffff, and its value. */
      UChar32 highStart;
      int32_t highValueIndex;
  
      /* private: used by builder and unserialization functions */
      void *memory;           /* serialized bytes; NULL if not frozen yet */
      int32_t length;         /* number of serialized bytes at memory; 0 if not frozen yet */
      UBool isMemoryOwned;    /* true if the trie owns the memory */
      UBool padding1;
      int16_t padding2;
      UNewTrie2 *newTrie;     /* builder object; NULL when frozen */
  
  #ifdef UTRIE2_DEBUG
      const char *name;
  #endif
  };
  
  /**
   * Trie constants, defining shift widths, index array lengths, etc.
   *
   * These are needed for the runtime macros but users can treat these as
   * implementation details and skip to the actual public API further below.
   */
  enum {
      /** Shift size for getting the index-1 table offset. */
      UTRIE2_SHIFT_1=6+5,
  
      /** Shift size for getting the index-2 table offset. */
      UTRIE2_SHIFT_2=5,
  
      /**
       * Difference between the two shift sizes,
       * for getting an index-1 offset from an index-2 offset. 6=11-5
       */
      UTRIE2_SHIFT_1_2=UTRIE2_SHIFT_1-UTRIE2_SHIFT_2,
  
      /**
       * Number of index-1 entries for the BMP. 32=0x20
       * This part of the index-1 table is omitted from the serialized form.
       */
      UTRIE2_OMITTED_BMP_INDEX_1_LENGTH=0x10000>>UTRIE2_SHIFT_1,
  
      /** Number of code points per index-1 table entry. 2048=0x800 */
      UTRIE2_CP_PER_INDEX_1_ENTRY=1<<UTRIE2_SHIFT_1,
  
      /** Number of entries in an index-2 block. 64=0x40 */
      UTRIE2_INDEX_2_BLOCK_LENGTH=1<<UTRIE2_SHIFT_1_2,
  
      /** Mask for getting the lower bits for the in-index-2-block offset. */
      UTRIE2_INDEX_2_MASK=UTRIE2_INDEX_2_BLOCK_LENGTH-1,
  
      /** Number of entries in a data block. 32=0x20 */
      UTRIE2_DATA_BLOCK_LENGTH=1<<UTRIE2_SHIFT_2,
  
      /** Mask for getting the lower bits for the in-data-block offset. */
      UTRIE2_DATA_MASK=UTRIE2_DATA_BLOCK_LENGTH-1,
  
      /**
       * Shift size for shifting left the index array values.
       * Increases possible data size with 16-bit index values at the cost
       * of compactability.
       * This requires data blocks to be aligned by UTRIE2_DATA_GRANULARITY.
       */
      UTRIE2_INDEX_SHIFT=2,
  
      /** The alignment size of a data block. Also the granularity for compaction. */
      UTRIE2_DATA_GRANULARITY=1<<UTRIE2_INDEX_SHIFT,
  
      /* Fixed layout of the first part of the index array. ------------------- */
  
      /**
       * The BMP part of the index-2 table is fixed and linear and starts at offset 0.
       * Length=2048=0x800=0x10000>>UTRIE2_SHIFT_2.
       */
      UTRIE2_INDEX_2_OFFSET=0,
  
      /**
       * The part of the index-2 table for U+D800..U+DBFF stores values for
       * lead surrogate code _units_ not code _points_.
       * Values for lead surrogate code _points_ are indexed with this portion of the table.
       * Length=32=0x20=0x400>>UTRIE2_SHIFT_2. (There are 1024=0x400 lead surrogates.)
       */
      UTRIE2_LSCP_INDEX_2_OFFSET=0x10000>>UTRIE2_SHIFT_2,
      UTRIE2_LSCP_INDEX_2_LENGTH=0x400>>UTRIE2_SHIFT_2,
  
      /** Count the lengths of both BMP pieces. 2080=0x820 */
      UTRIE2_INDEX_2_BMP_LENGTH=UTRIE2_LSCP_INDEX_2_OFFSET+UTRIE2_LSCP_INDEX_2_LENGTH,
  
      /**
       * The 2-byte UTF-8 version of the index-2 table follows at offset 2080=0x820.
       * Length 32=0x20 for lead bytes C0..DF, regardless of UTRIE2_SHIFT_2.
       */
      UTRIE2_UTF8_2B_INDEX_2_OFFSET=UTRIE2_INDEX_2_BMP_LENGTH,
      UTRIE2_UTF8_2B_INDEX_2_LENGTH=0x800>>6,  /* U+0800 is the first code point after 2-byte UTF-8 */
  
      /**
       * The index-1 table, only used for supplementary code points, at offset 2112=0x840.
       * Variable length, for code points up to highStart, where the last single-value range starts.
       * Maximum length 512=0x200=0x100000>>UTRIE2_SHIFT_1.
       * (For 0x100000 supplementary code points U+10000..U+10ffff.)
       *
       * The part of the index-2 table for supplementary code points starts
       * after this index-1 table.
       *
       * Both the index-1 table and the following part of the index-2 table
       * are omitted completely if there is only BMP data.
       */
      UTRIE2_INDEX_1_OFFSET=UTRIE2_UTF8_2B_INDEX_2_OFFSET+UTRIE2_UTF8_2B_INDEX_2_LENGTH,
      UTRIE2_MAX_INDEX_1_LENGTH=0x100000>>UTRIE2_SHIFT_1,
  
      /*
       * Fixed layout of the first part of the data array. -----------------------
       * Starts with 4 blocks (128=0x80 entries) for ASCII.
       */
  
      /**
       * The illegal-UTF-8 data block follows the ASCII block, at offset 128=0x80.
       * Used with linear access for single bytes 0..0xbf for simple error handling.
       * Length 64=0x40, not UTRIE2_DATA_BLOCK_LENGTH.
       */
      UTRIE2_BAD_UTF8_DATA_OFFSET=0x80,
  
      /** The start of non-linear-ASCII data blocks, at offset 192=0xc0. */
      UTRIE2_DATA_START_OFFSET=0xc0
  };
  
  /* Internal functions and macros -------------------------------------------- */
  
  /**
   * Internal function for part of the UTRIE2_U8_NEXTxx() macro implementations.
   * Do not call directly.
   * @internal
   */
  U_CAPI int32_t U_EXPORT2
  utrie2_internalU8NextIndex(const UTrie2 *trie, UChar32 c,
                             const uint8_t *src, const uint8_t *limit);
  
  /**
   * Internal function for part of the UTRIE2_U8_PREVxx() macro implementations.
   * Do not call directly.
   * @internal
   */
  U_CAPI int32_t U_EXPORT2
  utrie2_internalU8PrevIndex(const UTrie2 *trie, UChar32 c,
                             const uint8_t *start, const uint8_t *src);
  
  
  /** Internal low-level trie getter. Returns a data index. */
  #define _UTRIE2_INDEX_RAW(offset, trieIndex, c) \
      (((int32_t)((trieIndex)[(offset)+((c)>>UTRIE2_SHIFT_2)]) \
      <<UTRIE2_INDEX_SHIFT)+ \
      ((c)&UTRIE2_DATA_MASK))
  
  /** Internal trie getter from a UTF-16 single/lead code unit. Returns the data index. */
  #define _UTRIE2_INDEX_FROM_U16_SINGLE_LEAD(trieIndex, c) _UTRIE2_INDEX_RAW(0, trieIndex, c)
  
  /** Internal trie getter from a lead surrogate code point (D800..DBFF). Returns the data index. */
  #define _UTRIE2_INDEX_FROM_LSCP(trieIndex, c) \
      _UTRIE2_INDEX_RAW(UTRIE2_LSCP_INDEX_2_OFFSET-(0xd800>>UTRIE2_SHIFT_2), trieIndex, c)
  
  /** Internal trie getter from a BMP code point. Returns the data index. */
  #define _UTRIE2_INDEX_FROM_BMP(trieIndex, c) \
      _UTRIE2_INDEX_RAW(U_IS_LEAD(c) ? UTRIE2_LSCP_INDEX_2_OFFSET-(0xd800>>UTRIE2_SHIFT_2) : 0, \
                        trieIndex, c)
  
  /** Internal trie getter from a supplementary code point below highStart. Returns the data index. */
  #define _UTRIE2_INDEX_FROM_SUPP(trieIndex, c) \
      (((int32_t)((trieIndex)[ \
          (trieIndex)[(UTRIE2_INDEX_1_OFFSET-UTRIE2_OMITTED_BMP_INDEX_1_LENGTH)+ \
                        ((c)>>UTRIE2_SHIFT_1)]+ \
          (((c)>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK)]) \
      <<UTRIE2_INDEX_SHIFT)+ \
      ((c)&UTRIE2_DATA_MASK))
  
  /**
   * Internal trie getter from a code point, with checking that c is in 0..10FFFF.
   * Returns the data index.
   */
  #define _UTRIE2_INDEX_FROM_CP(trie, asciiOffset, c) \
      ((uint32_t)(c)<0xd800 ? \
          _UTRIE2_INDEX_RAW(0, (trie)->index, c) : \
          (uint32_t)(c)<=0xffff ? \
              _UTRIE2_INDEX_RAW( \
                  (c)<=0xdbff ? UTRIE2_LSCP_INDEX_2_OFFSET-(0xd800>>UTRIE2_SHIFT_2) : 0, \
                  (trie)->index, c) : \
              (uint32_t)(c)>0x10ffff ? \
                  (asciiOffset)+UTRIE2_BAD_UTF8_DATA_OFFSET : \
                  (c)>=(trie)->highStart ? \
                      (trie)->highValueIndex : \
                      _UTRIE2_INDEX_FROM_SUPP((trie)->index, c))
  
  /** Internal trie getter from a UTF-16 single/lead code unit. Returns the data. */
  #define _UTRIE2_GET_FROM_U16_SINGLE_LEAD(trie, data, c) \
      (trie)->data[_UTRIE2_INDEX_FROM_U16_SINGLE_LEAD((trie)->index, c)]
  
  /** Internal trie getter from a supplementary code point. Returns the data. */
  #define _UTRIE2_GET_FROM_SUPP(trie, data, c) \
      (trie)->data[(c)>=(trie)->highStart ? (trie)->highValueIndex : \
                   _UTRIE2_INDEX_FROM_SUPP((trie)->index, c)]
  
  /**
   * Internal trie getter from a code point, with checking that c is in 0..10FFFF.
   * Returns the data.
   */
  #define _UTRIE2_GET(trie, data, asciiOffset, c) \
      (trie)->data[_UTRIE2_INDEX_FROM_CP(trie, asciiOffset, c)]
  
  /** Internal next-post-increment: get the next code point (c) and its data. */
  #define _UTRIE2_U16_NEXT(trie, data, src, limit, c, result) UPRV_BLOCK_MACRO_BEGIN { \
      { \
          uint16_t __c2; \
          (c)=*(src)++; \
          if(!U16_IS_LEAD(c)) { \
              (result)=_UTRIE2_GET_FROM_U16_SINGLE_LEAD(trie, data, c); \
          } else if((src)==(limit) || !U16_IS_TRAIL(__c2=*(src))) { \
              (result)=(trie)->data[_UTRIE2_INDEX_FROM_LSCP((trie)->index, c)]; \
          } else { \
              ++(src); \
              (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
              (result)=_UTRIE2_GET_FROM_SUPP((trie), data, (c)); \
          } \
      } \
  } UPRV_BLOCK_MACRO_END
  
  /** Internal pre-decrement-previous: get the previous code point (c) and its data */
  #define _UTRIE2_U16_PREV(trie, data, start, src, c, result) UPRV_BLOCK_MACRO_BEGIN { \
      { \
          uint16_t __c2; \
          (c)=*--(src); \
          if(!U16_IS_TRAIL(c) || (src)==(start) || !U16_IS_LEAD(__c2=*((src)-1))) { \
              (result)=(trie)->data[_UTRIE2_INDEX_FROM_BMP((trie)->index, c)]; \
          } else { \
              --(src); \
              (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
              (result)=_UTRIE2_GET_FROM_SUPP((trie), data, (c)); \
          } \
      } \
  } UPRV_BLOCK_MACRO_END
  
  /** Internal UTF-8 next-post-increment: get the next code point's data. */
  #define _UTRIE2_U8_NEXT(trie, ascii, data, src, limit, result) UPRV_BLOCK_MACRO_BEGIN { \
      uint8_t __lead=(uint8_t)*(src)++; \
      if(U8_IS_SINGLE(__lead)) { \
          (result)=(trie)->ascii[__lead]; \
      } else { \
          uint8_t __t1, __t2; \
          if( /* handle U+0800..U+FFFF inline */ \
              0xe0<=__lead && __lead<0xf0 && ((src)+1)<(limit) && \
              U8_IS_VALID_LEAD3_AND_T1(__lead, __t1=(uint8_t)*(src)) && \
              (__t2=(uint8_t)(*((src)+1)-0x80))<= 0x3f \
          ) { \
              (src)+=2; \
              (result)=(trie)->data[ \
                  ((int32_t)((trie)->index[((__lead-0xe0)<<(12-UTRIE2_SHIFT_2))+ \
                                           ((__t1&0x3f)<<(6-UTRIE2_SHIFT_2))+(__t2>>UTRIE2_SHIFT_2)]) \
                  <<UTRIE2_INDEX_SHIFT)+ \
                  (__t2&UTRIE2_DATA_MASK)]; \
          } else if( /* handle U+0080..U+07FF inline */ \
              __lead<0xe0 && __lead>=0xc2 && (src)<(limit) && \
              (__t1=(uint8_t)(*(src)-0x80))<=0x3f \
          ) { \
              ++(src); \
              (result)=(trie)->data[ \
                  (trie)->index[(UTRIE2_UTF8_2B_INDEX_2_OFFSET-0xc0)+__lead]+ \
                  __t1]; \
          } else { \
              int32_t __index=utrie2_internalU8NextIndex((trie), __lead, (const uint8_t *)(src), \
                                                                         (const uint8_t *)(limit)); \
              (src)+=__index&7; \
              (result)=(trie)->data[__index>>3]; \
          } \
      } \
  } UPRV_BLOCK_MACRO_END
  
  /** Internal UTF-8 pre-decrement-previous: get the previous code point's data. */
  #define _UTRIE2_U8_PREV(trie, ascii, data, start, src, result) UPRV_BLOCK_MACRO_BEGIN { \
      uint8_t __b=(uint8_t)*--(src); \
      if(U8_IS_SINGLE(__b)) { \
          (result)=(trie)->ascii[__b]; \
      } else { \
          int32_t __index=utrie2_internalU8PrevIndex((trie), __b, (const uint8_t *)(start), \
                                                                  (const uint8_t *)(src)); \
          (src)-=__index&7; \
          (result)=(trie)->data[__index>>3]; \
      } \
  } UPRV_BLOCK_MACRO_END
  
  U_CDECL_END
  
  #endif
  