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collationdatareader.h (10346B)

---

// © 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 char16_t *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() = delete;  // 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.
*
* char16_t *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__