You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
121 lines
4.7 KiB
CoffeeScript
121 lines
4.7 KiB
CoffeeScript
7 years ago
|
inflate = require 'tiny-inflate'
|
||
|
|
||
|
class UnicodeTrie
|
||
|
# Shift size for getting the index-1 table offset.
|
||
|
SHIFT_1 = 6 + 5
|
||
|
|
||
|
# Shift size for getting the index-2 table offset.
|
||
|
SHIFT_2 = 5
|
||
|
|
||
|
# Difference between the two shift sizes,
|
||
|
# for getting an index-1 offset from an index-2 offset. 6=11-5
|
||
|
SHIFT_1_2 = SHIFT_1 - 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.
|
||
|
OMITTED_BMP_INDEX_1_LENGTH = 0x10000 >> SHIFT_1
|
||
|
|
||
|
# Number of entries in an index-2 block. 64=0x40
|
||
|
INDEX_2_BLOCK_LENGTH = 1 << SHIFT_1_2
|
||
|
|
||
|
# Mask for getting the lower bits for the in-index-2-block offset. */
|
||
|
INDEX_2_MASK = INDEX_2_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 DATA_GRANULARITY.
|
||
|
INDEX_SHIFT = 2
|
||
|
|
||
|
# Number of entries in a data block. 32=0x20
|
||
|
DATA_BLOCK_LENGTH = 1 << SHIFT_2
|
||
|
|
||
|
# Mask for getting the lower bits for the in-data-block offset.
|
||
|
DATA_MASK = DATA_BLOCK_LENGTH - 1
|
||
|
|
||
|
# 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>>SHIFT_2. (There are 1024=0x400 lead surrogates.)
|
||
|
LSCP_INDEX_2_OFFSET = 0x10000 >> SHIFT_2
|
||
|
LSCP_INDEX_2_LENGTH = 0x400 >> SHIFT_2
|
||
|
|
||
|
# Count the lengths of both BMP pieces. 2080=0x820
|
||
|
INDEX_2_BMP_LENGTH = LSCP_INDEX_2_OFFSET + 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 SHIFT_2.
|
||
|
UTF8_2B_INDEX_2_OFFSET = INDEX_2_BMP_LENGTH
|
||
|
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>>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.
|
||
|
INDEX_1_OFFSET = UTF8_2B_INDEX_2_OFFSET + UTF8_2B_INDEX_2_LENGTH
|
||
|
|
||
|
# The alignment size of a data block. Also the granularity for compaction.
|
||
|
DATA_GRANULARITY = 1 << INDEX_SHIFT
|
||
|
|
||
|
constructor: (data) ->
|
||
|
isBuffer = typeof data.readUInt32BE is 'function' and typeof data.slice is 'function'
|
||
|
|
||
|
if isBuffer or data instanceof Uint8Array
|
||
|
# read binary format
|
||
|
if isBuffer
|
||
|
@highStart = data.readUInt32BE 0
|
||
|
@errorValue = data.readUInt32BE 4
|
||
|
uncompressedLength = data.readUInt32BE 8
|
||
|
data = data.slice 12
|
||
|
else
|
||
|
view = new DataView data.buffer
|
||
|
@highStart = view.getUint32 0
|
||
|
@errorValue = view.getUint32 4
|
||
|
uncompressedLength = view.getUint32 8
|
||
|
data = data.subarray 12
|
||
|
|
||
|
# double inflate the actual trie data
|
||
|
data = inflate data, new Uint8Array uncompressedLength
|
||
|
data = inflate data, new Uint8Array uncompressedLength
|
||
|
@data = new Uint32Array data.buffer
|
||
|
|
||
|
else
|
||
|
# pre-parsed data
|
||
|
{@data, @highStart, @errorValue} = data
|
||
|
|
||
|
get: (codePoint) ->
|
||
|
if codePoint < 0 or codePoint > 0x10ffff
|
||
|
return @errorValue
|
||
|
|
||
|
if (codePoint < 0xd800 or (codePoint > 0xdbff and codePoint <= 0xffff))
|
||
|
# Ordinary BMP code point, excluding leading surrogates.
|
||
|
# BMP uses a single level lookup. BMP index starts at offset 0 in the index.
|
||
|
# data is stored in the index array itself.
|
||
|
index = (@data[codePoint >> SHIFT_2] << INDEX_SHIFT) + (codePoint & DATA_MASK)
|
||
|
return @data[index]
|
||
|
|
||
|
if codePoint <= 0xffff
|
||
|
# Lead Surrogate Code Point. A Separate index section is stored for
|
||
|
# lead surrogate code units and code points.
|
||
|
# The main index has the code unit data.
|
||
|
# For this function, we need the code point data.
|
||
|
index = (@data[LSCP_INDEX_2_OFFSET + ((codePoint - 0xd800) >> SHIFT_2)] << INDEX_SHIFT) + (codePoint & DATA_MASK)
|
||
|
return @data[index]
|
||
|
|
||
|
if codePoint < @highStart
|
||
|
# Supplemental code point, use two-level lookup.
|
||
|
index = @data[(INDEX_1_OFFSET - OMITTED_BMP_INDEX_1_LENGTH) + (codePoint >> SHIFT_1)]
|
||
|
index = @data[index + ((codePoint >> SHIFT_2) & INDEX_2_MASK)]
|
||
|
index = (index << INDEX_SHIFT) + (codePoint & DATA_MASK)
|
||
|
return @data[index]
|
||
|
|
||
|
return @data[@data.length - DATA_GRANULARITY]
|
||
|
|
||
|
module.exports = UnicodeTrie
|