icuSources/i18n/collationdatareader.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 *******************************************************************************
   5 * Copyright (C) 2013-2015, International Business Machines
   6 * Corporation and others.  All Rights Reserved.
   7 *******************************************************************************
   8 * collationdatareader.h
   9 *
  10 * created on: 2013feb07
  11 * created by: Markus W. Scherer
  12 */
  13
  14 #ifndef __COLLATIONDATAREADER_H__
  15 #define __COLLATIONDATAREADER_H__
  16
  17 #include "unicode/utypes.h"
  18
  19 #if !UCONFIG_NO_COLLATION
  20
  21 #include "unicode/udata.h"
  22
  23 struct UDataMemory;
  24
  25 U_NAMESPACE_BEGIN
  26
  27 struct CollationTailoring;
  28
  29 /**
  30  * Collation binary data reader.
  31  */
  32 struct U_I18N_API CollationDataReader /* all static */ {
  33     // The following constants are also copied into source/common/ucol_swp.cpp.
  34     // Keep them in sync!
  35     enum {
  36         /**
  37          * Number of int32_t indexes.
  38          *
  39          * Can be 2 if there are only options.
  40          * Can be 7 or 8 if there are only options and a script reordering.
  41          * The loader treats any index>=indexes[IX_INDEXES_LENGTH] as 0.
  42          */
  43         IX_INDEXES_LENGTH,  // 0
  44         /**
  45          * Bits 31..24: numericPrimary, for numeric collation
  46          *      23..16: fast Latin format version (0 = no fast Latin table)
  47          *      15.. 0: options bit set
  48          */
  49         IX_OPTIONS,
  50         IX_RESERVED2,
  51         IX_RESERVED3,
  52
  53         /** Array offset to Jamo CE32s in ce32s[], or <0 if none. */
  54         IX_JAMO_CE32S_START,  // 4
  55
  56         // Byte offsets from the start of the data, after the generic header.
  57         // The indexes[] are at byte offset 0, other data follows.
  58         // Each data item is aligned properly.
  59         // The data items should be in descending order of unit size,
  60         // to minimize the need for padding.
  61         // Each item's byte length is given by the difference between its offset and
  62         // the next index/offset value.
  63         /** Byte offset to int32_t reorderCodes[]. */
  64         IX_REORDER_CODES_OFFSET,
  65         /**
  66          * Byte offset to uint8_t reorderTable[].
  67          * Empty table if <256 bytes (padding only).
  68          * Otherwise 256 bytes or more (with padding).
  69          */
  70         IX_REORDER_TABLE_OFFSET,
  71         /** Byte offset to the collation trie. Its length is a multiple of 8 bytes. */
  72         IX_TRIE_OFFSET,
  73
  74         IX_RESERVED8_OFFSET,  // 8
  75         /** Byte offset to int64_t ces[]. */
  76         IX_CES_OFFSET,
  77         IX_RESERVED10_OFFSET,
  78         /** Byte offset to uint32_t ce32s[]. */
  79         IX_CE32S_OFFSET,
  80
  81         /** Byte offset to uint32_t rootElements[]. */
  82         IX_ROOT_ELEMENTS_OFFSET,  // 12
  83         /** Byte offset to UChar *contexts[]. */
  84         IX_CONTEXTS_OFFSET,
  85         /** Byte offset to uint16_t [] with serialized unsafeBackwardSet. */
  86         IX_UNSAFE_BWD_OFFSET,
  87         /** Byte offset to uint16_t fastLatinTable[]. */
  88         IX_FAST_LATIN_TABLE_OFFSET,
  89
  90         /** Byte offset to uint16_t scripts[]. */
  91         IX_SCRIPTS_OFFSET,  // 16
  92         /**
  93          * Byte offset to UBool compressibleBytes[].
  94          * Empty table if <256 bytes (padding only).
  95          * Otherwise 256 bytes or more (with padding).
  96          */
  97         IX_COMPRESSIBLE_BYTES_OFFSET,
  98         IX_RESERVED18_OFFSET,
  99         IX_TOTAL_SIZE
 100     };
 101
 102     static void read(const CollationTailoring *base, const uint8_t *inBytes, int32_t inLength,
 103                      CollationTailoring &tailoring, UErrorCode &errorCode);
 104
 105     static UBool U_CALLCONV
 106     isAcceptable(void *context, const char *type, const char *name, const UDataInfo *pInfo);
 107
 108 private:
 109     CollationDataReader();  // no constructor
 110 };
 111
 112 /*
 113  * Format of collation data (ucadata.icu, binary data in coll/ *.res files).
 114  * Format version 5.
 115  *
 116  * The root collation data is stored in the ucadata.icu file.
 117  * Tailorings are stored inside .res resource bundle files, with a complete file header.
 118  *
 119  * Collation data begins with a standard ICU data file header
 120  * (DataHeader, see ucmndata.h and unicode/udata.h).
 121  * The UDataInfo.dataVersion field contains the UCA and other version numbers,
 122  * see the comments for CollationTailoring.version.
 123  *
 124  * After the header, the file contains the following parts.
 125  * Constants are defined as enum values of the CollationDataReader class.
 126  * See also the Collation class.
 127  *
 128  * int32_t indexes[indexesLength];
 129  *      The indexes array has variable length.
 130  *      Some tailorings only need the length and the options,
 131  *      others only add reorderCodes and the reorderTable,
 132  *      some need to store mappings.
 133  *      Only as many indexes are stored as needed to read all of the data.
 134  *
 135  *      Index 0: indexesLength
 136  *      Index 1: numericPrimary, CollationFastLatin::VERSION, and options: see IX_OPTIONS
 137  *      Index 2..3: Unused/reserved/0.
 138  *      Index 4: Index into the ce32s array where the CE32s of the conjoining Jamo
 139  *               are stored in a short, contiguous part of the ce32s array.
 140  *
 141  *      Indexes 5..19 are byte offsets in ascending order.
 142  *      Each byte offset marks the start of the next part in the data file,
 143  *      and the end of the previous one.
 144  *      When two consecutive byte offsets are the same (or too short),
 145  *      then the corresponding part is empty.
 146  *      Byte offsets are offsets from after the header,
 147  *      that is, from the beginning of the indexes[].
 148  *      Each part starts at an offset with proper alignment for its data.
 149  *      If necessary, the previous part may include padding bytes to achieve this alignment.
 150  *      The last byte offset that is stored in the indexes indicates the total size of the data
 151  *      (starting with the indexes).
 152  *
 153  * int32_t reorderCodes[]; -- empty in root
 154  *      The list of script and reordering codes.
 155  *
 156  *      Beginning with format version 5, this array may optionally
 157  *      have trailing entries with a full list of reorder ranges
 158  *      as described for CollationSettings::reorderRanges.
 159  *
 160  *      Script or reorder codes are first and do not exceed 16-bit values.
 161  *      Range limits are stored in the upper 16 bits, and are never 0.
 162  *      Split this array into reorder codes and ranges at the first entry
 163  *      with non-zero upper 16 bits.
 164  *
 165  *      If the ranges are missing but needed for split-reordered primary lead bytes,
 166  *      then they are regenerated at load time.
 167  *
 168  * uint8_t reorderTable[256]; -- empty in root; can be longer to include padding bytes
 169  *      Primary-weight lead byte permutation table.
 170  *      Normally present when the reorderCodes are, but can be built at load time.
 171  *
 172  *      Beginning with format version 5, a 0 entry at a non-zero index
 173  *      (which is otherwise an illegal value)
 174  *      means that the primary lead byte is "split"
 175  *      (there are different offsets for primaries that share that lead byte)
 176  *      and the reordering offset must be determined via the reorder ranges
 177  *      that are either stored as part of the reorderCodes array
 178  *      or regenerated at load time.
 179  *
 180  * UTrie2 trie; -- see utrie2_impl.h and utrie2.h
 181  *      The trie holds the main collation data. Each code point is mapped to a 32-bit value.
 182  *      It encodes a simple collation element (CE) in compact form, unless bits 7..6 are both set,
 183  *      in which case it is a special CE32 and contains a 4-bit tag and further data.
 184  *      See the Collation class for details.
 185  *
 186  *      The trie has a value for each lead surrogate code unit with some bits encoding
 187  *      collective properties of the 1024 supplementary characters whose UTF-16 form starts with
 188  *      the lead surrogate. See Collation::LEAD_SURROGATE_TAG..
 189  *
 190  * int64_t ces[];
 191  *      64-bit CEs and expansions that cannot be stored in a more compact form.
 192  *
 193  * uint32_t ce32s[];
 194  *      CE32s for expansions in compact form, and for characters whose trie values
 195  *      contain special data.
 196  *
 197  * uint32_t rootElements[]; -- empty in all tailorings
 198  *      Compact storage for all of the CEs that occur in the root collation.
 199  *      See the CollationRootElements class.
 200  *
 201  * UChar *contexts[];
 202  *      Serialized UCharsTrie structures with prefix (pre-context) and contraction mappings.
 203  *
 204  * uint16_t unsafeBackwardSet[]; -- see UnicodeSet::serialize()
 205  *      Serialized form of characters that are unsafe when iterating backwards,
 206  *      and at the end of an identical string prefix.
 207  *      Back up to a safe character.
 208  *      Lead surrogates are "unsafe" when any of their corresponding supplementary
 209  *      code points are unsafe.
 210  *      Does not include [:^lccc=0:][:^tccc=0:].
 211  *      For each tailoring, the root unsafeBackwardSet is subtracted.
 212  *      (As a result, in many tailorings no set needs to be stored.)
 213  *
 214  * uint16_t fastLatinTable[];
 215  *      Optional optimization for Latin text.
 216  *      See the CollationFastLatin class.
 217  *
 218  * uint16_t scripts[]; -- empty in all tailorings
 219  *      Format version 5:
 220  *      uint16_t numScripts;
 221  *      uint16_t scriptsIndex[numScripts+16];
 222  *      uint16_t scriptStarts[];
 223  *      See CollationData::numScripts etc.
 224  *
 225  *      Format version 4:
 226  *      Table of the reordering groups with their first and last lead bytes,
 227  *      and their script and reordering codes.
 228  *      See CollationData::scripts.
 229  *
 230  * UBool compressibleBytes[]; -- empty in all tailorings
 231  *      Flag for getSortKey(), indicating primary weight lead bytes that are compressible.
 232  *
 233  * -----------------
 234  * Changes for formatVersion 5 (ICU 55)
 235  *
 236  * Reordering moves single scripts, not groups of scripts.
 237  * Reorder ranges are optionally appended to the reorderCodes,
 238  * and a 0 entry in the reorderTable indicates a split lead byte.
 239  * The scripts data has a new format.
 240  *
 241  * The rootElements may contain secondary and tertiary weights below common=05.
 242  * (Used for small Hiragana letters.)
 243  * Where is occurs, there is also an explicit unit with common secondary & tertiary weights.
 244  * There are no other data structure changes, but builder code needs to be able to handle such data.
 245  *
 246  * The collation element for the merge separator code point U+FFFE
 247  * does not necessarily have special, unique secondary/tertiary weights any more.
 248  */
 249
 250 U_NAMESPACE_END
 251
 252 #endif  // !UCONFIG_NO_COLLATION
 253 #endif  // __COLLATIONDATAREADER_H__