flow like the river

VISUALIZACION/node_modules/unicode-trie/index.coffee

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+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