text: // © 2016 and later: Unicode, Inc. and others.
  // License & terms of use: http://www.unicode.org/copyright.html
  /*
  *******************************************************************************
  * Copyright (C) 2013-2015, International Business Machines
  * Corporation and others.  All Rights Reserved.
  *******************************************************************************
  * collationdatareader.h
  *
  * created on: 2013feb07
  * created by: Markus W. Scherer
  */
  
  #ifndef __COLLATIONDATAREADER_H__
  #define __COLLATIONDATAREADER_H__
  
  #include "unicode/utypes.h"
  
  #if !UCONFIG_NO_COLLATION
  
  #include "unicode/udata.h"
  
  struct UDataMemory;
  
  U_NAMESPACE_BEGIN
  
  struct CollationTailoring;
  
  /**
   * Collation binary data reader.
   */
  struct U_I18N_API CollationDataReader /* all static */ {
      // The following constants are also copied into source/common/ucol_swp.cpp.
      // Keep them in sync!
      enum {
          /**
           * Number of int32_t indexes.
           *
           * Can be 2 if there are only options.
           * Can be 7 or 8 if there are only options and a script reordering.
           * The loader treats any index>=indexes[IX_INDEXES_LENGTH] as 0.
           */
          IX_INDEXES_LENGTH,  // 0
          /**
           * Bits 31..24: numericPrimary, for numeric collation
           *      23..16: fast Latin format version (0 = no fast Latin table)
           *      15.. 0: options bit set
           */
          IX_OPTIONS,
          IX_RESERVED2,
          IX_RESERVED3,
  
          /** Array offset to Jamo CE32s in ce32s[], or <0 if none. */
          IX_JAMO_CE32S_START,  // 4
  
          // Byte offsets from the start of the data, after the generic header.
          // The indexes[] are at byte offset 0, other data follows.
          // Each data item is aligned properly.
          // The data items should be in descending order of unit size,
          // to minimize the need for padding.
          // Each item's byte length is given by the difference between its offset and
          // the next index/offset value.
          /** Byte offset to int32_t reorderCodes[]. */
          IX_REORDER_CODES_OFFSET,
          /**
           * Byte offset to uint8_t reorderTable[].
           * Empty table if <256 bytes (padding only).
           * Otherwise 256 bytes or more (with padding).
           */
          IX_REORDER_TABLE_OFFSET,
          /** Byte offset to the collation trie. Its length is a multiple of 8 bytes. */
          IX_TRIE_OFFSET,
  
          IX_RESERVED8_OFFSET,  // 8
          /** Byte offset to int64_t ces[]. */
          IX_CES_OFFSET,
          IX_RESERVED10_OFFSET,
          /** Byte offset to uint32_t ce32s[]. */
          IX_CE32S_OFFSET,
  
          /** Byte offset to uint32_t rootElements[]. */
          IX_ROOT_ELEMENTS_OFFSET,  // 12
          /** Byte offset to UChar *contexts[]. */
          IX_CONTEXTS_OFFSET,
          /** Byte offset to uint16_t [] with serialized unsafeBackwardSet. */
          IX_UNSAFE_BWD_OFFSET,
          /** Byte offset to uint16_t fastLatinTable[]. */
          IX_FAST_LATIN_TABLE_OFFSET,
  
          /** Byte offset to uint16_t scripts[]. */
          IX_SCRIPTS_OFFSET,  // 16
          /**
           * Byte offset to UBool compressibleBytes[].
           * Empty table if <256 bytes (padding only).
           * Otherwise 256 bytes or more (with padding).
           */
          IX_COMPRESSIBLE_BYTES_OFFSET,
          IX_RESERVED18_OFFSET,
          IX_TOTAL_SIZE
      };
  
      static void read(const CollationTailoring *base, const uint8_t *inBytes, int32_t inLength,
                       CollationTailoring &tailoring, UErrorCode &errorCode);
  
      static UBool U_CALLCONV
      isAcceptable(void *context, const char *type, const char *name, const UDataInfo *pInfo);
  
  private:
      CollationDataReader();  // no constructor
  };
  
  /*
   * Format of collation data (ucadata.icu, binary data in coll/ *.res files).
   * Format version 5.
   *
   * The root collation data is stored in the ucadata.icu file.
   * Tailorings are stored inside .res resource bundle files, with a complete file header.
   *
   * Collation data begins with a standard ICU data file header
   * (DataHeader, see ucmndata.h and unicode/udata.h).
   * The UDataInfo.dataVersion field contains the UCA and other version numbers,
   * see the comments for CollationTailoring.version.
   *
   * After the header, the file contains the following parts.
   * Constants are defined as enum values of the CollationDataReader class.
   * See also the Collation class.
   *
   * int32_t indexes[indexesLength];
   *      The indexes array has variable length.
   *      Some tailorings only need the length and the options,
   *      others only add reorderCodes and the reorderTable,
   *      some need to store mappings.
   *      Only as many indexes are stored as needed to read all of the data.
   *
   *      Index 0: indexesLength
   *      Index 1: numericPrimary, CollationFastLatin::VERSION, and options: see IX_OPTIONS
   *      Index 2..3: Unused/reserved/0.
   *      Index 4: Index into the ce32s array where the CE32s of the conjoining Jamo
   *               are stored in a short, contiguous part of the ce32s array.
   *
   *      Indexes 5..19 are byte offsets in ascending order.
   *      Each byte offset marks the start of the next part in the data file,
   *      and the end of the previous one.
   *      When two consecutive byte offsets are the same (or too short),
   *      then the corresponding part is empty.
   *      Byte offsets are offsets from after the header,
   *      that is, from the beginning of the indexes[].
   *      Each part starts at an offset with proper alignment for its data.
   *      If necessary, the previous part may include padding bytes to achieve this alignment.
   *      The last byte offset that is stored in the indexes indicates the total size of the data
   *      (starting with the indexes).
   *
   * int32_t reorderCodes[]; -- empty in root
   *      The list of script and reordering codes.
   *
   *      Beginning with format version 5, this array may optionally
   *      have trailing entries with a full list of reorder ranges
   *      as described for CollationSettings::reorderRanges.
   *
   *      Script or reorder codes are first and do not exceed 16-bit values.
   *      Range limits are stored in the upper 16 bits, and are never 0.
   *      Split this array into reorder codes and ranges at the first entry
   *      with non-zero upper 16 bits.
   *
   *      If the ranges are missing but needed for split-reordered primary lead bytes,
   *      then they are regenerated at load time.
   *
   * uint8_t reorderTable[256]; -- empty in root; can be longer to include padding bytes
   *      Primary-weight lead byte permutation table.
   *      Normally present when the reorderCodes are, but can be built at load time.
   *
   *      Beginning with format version 5, a 0 entry at a non-zero index
   *      (which is otherwise an illegal value)
   *      means that the primary lead byte is "split"
   *      (there are different offsets for primaries that share that lead byte)
   *      and the reordering offset must be determined via the reorder ranges
   *      that are either stored as part of the reorderCodes array
   *      or regenerated at load time.
   *
   * UTrie2 trie; -- see utrie2_impl.h and utrie2.h
   *      The trie holds the main collation data. Each code point is mapped to a 32-bit value.
   *      It encodes a simple collation element (CE) in compact form, unless bits 7..6 are both set,
   *      in which case it is a special CE32 and contains a 4-bit tag and further data.
   *      See the Collation class for details.
   *
   *      The trie has a value for each lead surrogate code unit with some bits encoding
   *      collective properties of the 1024 supplementary characters whose UTF-16 form starts with
   *      the lead surrogate. See Collation::LEAD_SURROGATE_TAG..
   *
   * int64_t ces[];
   *      64-bit CEs and expansions that cannot be stored in a more compact form.
   *
   * uint32_t ce32s[];
   *      CE32s for expansions in compact form, and for characters whose trie values
   *      contain special data.
   *
   * uint32_t rootElements[]; -- empty in all tailorings
   *      Compact storage for all of the CEs that occur in the root collation.
   *      See the CollationRootElements class.
   *
   * UChar *contexts[];
   *      Serialized UCharsTrie structures with prefix (pre-context) and contraction mappings.
   *
   * uint16_t unsafeBackwardSet[]; -- see UnicodeSet::serialize()
   *      Serialized form of characters that are unsafe when iterating backwards,
   *      and at the end of an identical string prefix.
   *      Back up to a safe character.
   *      Lead surrogates are "unsafe" when any of their corresponding supplementary
   *      code points are unsafe.
   *      Does not include [:^lccc=0:][:^tccc=0:].
   *      For each tailoring, the root unsafeBackwardSet is subtracted.
   *      (As a result, in many tailorings no set needs to be stored.)
   *
   * uint16_t fastLatinTable[];
   *      Optional optimization for Latin text.
   *      See the CollationFastLatin class.
   *
   * uint16_t scripts[]; -- empty in all tailorings
   *      Format version 5:
   *      uint16_t numScripts;
   *      uint16_t scriptsIndex[numScripts+16];
   *      uint16_t scriptStarts[];
   *      See CollationData::numScripts etc.
   *
   *      Format version 4:
   *      Table of the reordering groups with their first and last lead bytes,
   *      and their script and reordering codes.
   *      See CollationData::scripts.
   *
   * UBool compressibleBytes[]; -- empty in all tailorings
   *      Flag for getSortKey(), indicating primary weight lead bytes that are compressible.
   *
   * -----------------
   * Changes for formatVersion 5 (ICU 55)
   *
   * Reordering moves single scripts, not groups of scripts.
   * Reorder ranges are optionally appended to the reorderCodes,
   * and a 0 entry in the reorderTable indicates a split lead byte.
   * The scripts data has a new format.
   *
   * The rootElements may contain secondary and tertiary weights below common=05.
   * (Used for small Hiragana letters.)
   * Where is occurs, there is also an explicit unit with common secondary & tertiary weights.
   * There are no other data structure changes, but builder code needs to be able to handle such data.
   *
   * The collation element for the merge separator code point U+FFFE
   * does not necessarily have special, unique secondary/tertiary weights any more.
   */
  
  U_NAMESPACE_END
  
  #endif  // !UCONFIG_NO_COLLATION
  #endif  // __COLLATIONDATAREADER_H__
  