mirror of
https://gitlab.com/berufsschul-ae/blitzchat.git
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555 lines
21 KiB
JavaScript
555 lines
21 KiB
JavaScript
"use strict";
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var Buffer = require("safer-buffer").Buffer;
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// Multibyte codec. In this scheme, a character is represented by 1 or more bytes.
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// Our codec supports UTF-16 surrogates, extensions for GB18030 and unicode sequences.
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// To save memory and loading time, we read table files only when requested.
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exports._dbcs = DBCSCodec;
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var UNASSIGNED = -1,
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GB18030_CODE = -2,
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SEQ_START = -10,
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NODE_START = -1000,
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UNASSIGNED_NODE = new Array(0x100),
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DEF_CHAR = -1;
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for (var i = 0; i < 0x100; i++)
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UNASSIGNED_NODE[i] = UNASSIGNED;
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// Class DBCSCodec reads and initializes mapping tables.
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function DBCSCodec(codecOptions, iconv) {
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this.encodingName = codecOptions.encodingName;
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if (!codecOptions)
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throw new Error("DBCS codec is called without the data.")
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if (!codecOptions.table)
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throw new Error("Encoding '" + this.encodingName + "' has no data.");
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// Load tables.
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var mappingTable = codecOptions.table();
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// Decode tables: MBCS -> Unicode.
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// decodeTables is a trie, encoded as an array of arrays of integers. Internal arrays are trie nodes and all have len = 256.
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// Trie root is decodeTables[0].
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// Values: >= 0 -> unicode character code. can be > 0xFFFF
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// == UNASSIGNED -> unknown/unassigned sequence.
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// == GB18030_CODE -> this is the end of a GB18030 4-byte sequence.
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// <= NODE_START -> index of the next node in our trie to process next byte.
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// <= SEQ_START -> index of the start of a character code sequence, in decodeTableSeq.
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this.decodeTables = [];
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this.decodeTables[0] = UNASSIGNED_NODE.slice(0); // Create root node.
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// Sometimes a MBCS char corresponds to a sequence of unicode chars. We store them as arrays of integers here.
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this.decodeTableSeq = [];
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// Actual mapping tables consist of chunks. Use them to fill up decode tables.
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for (var i = 0; i < mappingTable.length; i++)
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this._addDecodeChunk(mappingTable[i]);
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this.defaultCharUnicode = iconv.defaultCharUnicode;
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// Encode tables: Unicode -> DBCS.
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// `encodeTable` is array mapping from unicode char to encoded char. All its values are integers for performance.
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// Because it can be sparse, it is represented as array of buckets by 256 chars each. Bucket can be null.
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// Values: >= 0 -> it is a normal char. Write the value (if <=256 then 1 byte, if <=65536 then 2 bytes, etc.).
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// == UNASSIGNED -> no conversion found. Output a default char.
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// <= SEQ_START -> it's an index in encodeTableSeq, see below. The character starts a sequence.
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this.encodeTable = [];
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// `encodeTableSeq` is used when a sequence of unicode characters is encoded as a single code. We use a tree of
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// objects where keys correspond to characters in sequence and leafs are the encoded dbcs values. A special DEF_CHAR key
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// means end of sequence (needed when one sequence is a strict subsequence of another).
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// Objects are kept separately from encodeTable to increase performance.
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this.encodeTableSeq = [];
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// Some chars can be decoded, but need not be encoded.
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var skipEncodeChars = {};
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if (codecOptions.encodeSkipVals)
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for (var i = 0; i < codecOptions.encodeSkipVals.length; i++) {
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var val = codecOptions.encodeSkipVals[i];
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if (typeof val === 'number')
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skipEncodeChars[val] = true;
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else
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for (var j = val.from; j <= val.to; j++)
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skipEncodeChars[j] = true;
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}
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// Use decode trie to recursively fill out encode tables.
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this._fillEncodeTable(0, 0, skipEncodeChars);
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// Add more encoding pairs when needed.
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if (codecOptions.encodeAdd) {
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for (var uChar in codecOptions.encodeAdd)
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if (Object.prototype.hasOwnProperty.call(codecOptions.encodeAdd, uChar))
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this._setEncodeChar(uChar.charCodeAt(0), codecOptions.encodeAdd[uChar]);
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}
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this.defCharSB = this.encodeTable[0][iconv.defaultCharSingleByte.charCodeAt(0)];
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if (this.defCharSB === UNASSIGNED) this.defCharSB = this.encodeTable[0]['?'];
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if (this.defCharSB === UNASSIGNED) this.defCharSB = "?".charCodeAt(0);
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// Load & create GB18030 tables when needed.
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if (typeof codecOptions.gb18030 === 'function') {
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this.gb18030 = codecOptions.gb18030(); // Load GB18030 ranges.
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// Add GB18030 decode tables.
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var thirdByteNodeIdx = this.decodeTables.length;
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var thirdByteNode = this.decodeTables[thirdByteNodeIdx] = UNASSIGNED_NODE.slice(0);
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var fourthByteNodeIdx = this.decodeTables.length;
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var fourthByteNode = this.decodeTables[fourthByteNodeIdx] = UNASSIGNED_NODE.slice(0);
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for (var i = 0x81; i <= 0xFE; i++) {
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var secondByteNodeIdx = NODE_START - this.decodeTables[0][i];
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var secondByteNode = this.decodeTables[secondByteNodeIdx];
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for (var j = 0x30; j <= 0x39; j++)
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secondByteNode[j] = NODE_START - thirdByteNodeIdx;
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}
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for (var i = 0x81; i <= 0xFE; i++)
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thirdByteNode[i] = NODE_START - fourthByteNodeIdx;
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for (var i = 0x30; i <= 0x39; i++)
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fourthByteNode[i] = GB18030_CODE
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}
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}
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DBCSCodec.prototype.encoder = DBCSEncoder;
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DBCSCodec.prototype.decoder = DBCSDecoder;
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// Decoder helpers
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DBCSCodec.prototype._getDecodeTrieNode = function(addr) {
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var bytes = [];
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for (; addr > 0; addr >>= 8)
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bytes.push(addr & 0xFF);
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if (bytes.length == 0)
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bytes.push(0);
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var node = this.decodeTables[0];
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for (var i = bytes.length-1; i > 0; i--) { // Traverse nodes deeper into the trie.
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var val = node[bytes[i]];
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if (val == UNASSIGNED) { // Create new node.
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node[bytes[i]] = NODE_START - this.decodeTables.length;
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this.decodeTables.push(node = UNASSIGNED_NODE.slice(0));
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}
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else if (val <= NODE_START) { // Existing node.
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node = this.decodeTables[NODE_START - val];
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}
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else
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throw new Error("Overwrite byte in " + this.encodingName + ", addr: " + addr.toString(16));
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}
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return node;
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}
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DBCSCodec.prototype._addDecodeChunk = function(chunk) {
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// First element of chunk is the hex mbcs code where we start.
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var curAddr = parseInt(chunk[0], 16);
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// Choose the decoding node where we'll write our chars.
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var writeTable = this._getDecodeTrieNode(curAddr);
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curAddr = curAddr & 0xFF;
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// Write all other elements of the chunk to the table.
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for (var k = 1; k < chunk.length; k++) {
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var part = chunk[k];
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if (typeof part === "string") { // String, write as-is.
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for (var l = 0; l < part.length;) {
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var code = part.charCodeAt(l++);
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if (0xD800 <= code && code < 0xDC00) { // Decode surrogate
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var codeTrail = part.charCodeAt(l++);
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if (0xDC00 <= codeTrail && codeTrail < 0xE000)
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writeTable[curAddr++] = 0x10000 + (code - 0xD800) * 0x400 + (codeTrail - 0xDC00);
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else
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throw new Error("Incorrect surrogate pair in " + this.encodingName + " at chunk " + chunk[0]);
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}
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else if (0x0FF0 < code && code <= 0x0FFF) { // Character sequence (our own encoding used)
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var len = 0xFFF - code + 2;
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var seq = [];
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for (var m = 0; m < len; m++)
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seq.push(part.charCodeAt(l++)); // Simple variation: don't support surrogates or subsequences in seq.
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writeTable[curAddr++] = SEQ_START - this.decodeTableSeq.length;
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this.decodeTableSeq.push(seq);
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}
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else
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writeTable[curAddr++] = code; // Basic char
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}
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}
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else if (typeof part === "number") { // Integer, meaning increasing sequence starting with prev character.
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var charCode = writeTable[curAddr - 1] + 1;
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for (var l = 0; l < part; l++)
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writeTable[curAddr++] = charCode++;
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}
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else
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throw new Error("Incorrect type '" + typeof part + "' given in " + this.encodingName + " at chunk " + chunk[0]);
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}
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if (curAddr > 0xFF)
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throw new Error("Incorrect chunk in " + this.encodingName + " at addr " + chunk[0] + ": too long" + curAddr);
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}
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// Encoder helpers
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DBCSCodec.prototype._getEncodeBucket = function(uCode) {
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var high = uCode >> 8; // This could be > 0xFF because of astral characters.
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if (this.encodeTable[high] === undefined)
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this.encodeTable[high] = UNASSIGNED_NODE.slice(0); // Create bucket on demand.
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return this.encodeTable[high];
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}
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DBCSCodec.prototype._setEncodeChar = function(uCode, dbcsCode) {
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var bucket = this._getEncodeBucket(uCode);
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var low = uCode & 0xFF;
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if (bucket[low] <= SEQ_START)
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this.encodeTableSeq[SEQ_START-bucket[low]][DEF_CHAR] = dbcsCode; // There's already a sequence, set a single-char subsequence of it.
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else if (bucket[low] == UNASSIGNED)
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bucket[low] = dbcsCode;
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}
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DBCSCodec.prototype._setEncodeSequence = function(seq, dbcsCode) {
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// Get the root of character tree according to first character of the sequence.
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var uCode = seq[0];
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var bucket = this._getEncodeBucket(uCode);
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var low = uCode & 0xFF;
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var node;
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if (bucket[low] <= SEQ_START) {
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// There's already a sequence with - use it.
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node = this.encodeTableSeq[SEQ_START-bucket[low]];
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}
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else {
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// There was no sequence object - allocate a new one.
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node = {};
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if (bucket[low] !== UNASSIGNED) node[DEF_CHAR] = bucket[low]; // If a char was set before - make it a single-char subsequence.
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bucket[low] = SEQ_START - this.encodeTableSeq.length;
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this.encodeTableSeq.push(node);
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}
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// Traverse the character tree, allocating new nodes as needed.
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for (var j = 1; j < seq.length-1; j++) {
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var oldVal = node[uCode];
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if (typeof oldVal === 'object')
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node = oldVal;
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else {
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node = node[uCode] = {}
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if (oldVal !== undefined)
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node[DEF_CHAR] = oldVal
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}
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}
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// Set the leaf to given dbcsCode.
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uCode = seq[seq.length-1];
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node[uCode] = dbcsCode;
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}
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DBCSCodec.prototype._fillEncodeTable = function(nodeIdx, prefix, skipEncodeChars) {
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var node = this.decodeTables[nodeIdx];
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for (var i = 0; i < 0x100; i++) {
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var uCode = node[i];
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var mbCode = prefix + i;
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if (skipEncodeChars[mbCode])
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continue;
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if (uCode >= 0)
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this._setEncodeChar(uCode, mbCode);
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else if (uCode <= NODE_START)
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this._fillEncodeTable(NODE_START - uCode, mbCode << 8, skipEncodeChars);
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else if (uCode <= SEQ_START)
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this._setEncodeSequence(this.decodeTableSeq[SEQ_START - uCode], mbCode);
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}
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}
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// == Encoder ==================================================================
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function DBCSEncoder(options, codec) {
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// Encoder state
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this.leadSurrogate = -1;
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this.seqObj = undefined;
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// Static data
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this.encodeTable = codec.encodeTable;
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this.encodeTableSeq = codec.encodeTableSeq;
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this.defaultCharSingleByte = codec.defCharSB;
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this.gb18030 = codec.gb18030;
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}
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DBCSEncoder.prototype.write = function(str) {
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var newBuf = Buffer.alloc(str.length * (this.gb18030 ? 4 : 3)),
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leadSurrogate = this.leadSurrogate,
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seqObj = this.seqObj, nextChar = -1,
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i = 0, j = 0;
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while (true) {
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// 0. Get next character.
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if (nextChar === -1) {
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if (i == str.length) break;
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var uCode = str.charCodeAt(i++);
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}
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else {
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var uCode = nextChar;
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nextChar = -1;
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}
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// 1. Handle surrogates.
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if (0xD800 <= uCode && uCode < 0xE000) { // Char is one of surrogates.
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if (uCode < 0xDC00) { // We've got lead surrogate.
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if (leadSurrogate === -1) {
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leadSurrogate = uCode;
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continue;
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} else {
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leadSurrogate = uCode;
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// Double lead surrogate found.
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uCode = UNASSIGNED;
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}
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} else { // We've got trail surrogate.
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if (leadSurrogate !== -1) {
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uCode = 0x10000 + (leadSurrogate - 0xD800) * 0x400 + (uCode - 0xDC00);
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leadSurrogate = -1;
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} else {
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// Incomplete surrogate pair - only trail surrogate found.
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uCode = UNASSIGNED;
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}
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}
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}
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else if (leadSurrogate !== -1) {
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// Incomplete surrogate pair - only lead surrogate found.
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nextChar = uCode; uCode = UNASSIGNED; // Write an error, then current char.
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leadSurrogate = -1;
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}
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// 2. Convert uCode character.
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var dbcsCode = UNASSIGNED;
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if (seqObj !== undefined && uCode != UNASSIGNED) { // We are in the middle of the sequence
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var resCode = seqObj[uCode];
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if (typeof resCode === 'object') { // Sequence continues.
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seqObj = resCode;
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continue;
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} else if (typeof resCode == 'number') { // Sequence finished. Write it.
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dbcsCode = resCode;
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} else if (resCode == undefined) { // Current character is not part of the sequence.
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// Try default character for this sequence
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resCode = seqObj[DEF_CHAR];
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if (resCode !== undefined) {
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dbcsCode = resCode; // Found. Write it.
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nextChar = uCode; // Current character will be written too in the next iteration.
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} else {
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// TODO: What if we have no default? (resCode == undefined)
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// Then, we should write first char of the sequence as-is and try the rest recursively.
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// Didn't do it for now because no encoding has this situation yet.
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// Currently, just skip the sequence and write current char.
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}
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}
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seqObj = undefined;
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}
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else if (uCode >= 0) { // Regular character
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var subtable = this.encodeTable[uCode >> 8];
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if (subtable !== undefined)
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dbcsCode = subtable[uCode & 0xFF];
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if (dbcsCode <= SEQ_START) { // Sequence start
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seqObj = this.encodeTableSeq[SEQ_START-dbcsCode];
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continue;
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}
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if (dbcsCode == UNASSIGNED && this.gb18030) {
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// Use GB18030 algorithm to find character(s) to write.
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var idx = findIdx(this.gb18030.uChars, uCode);
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if (idx != -1) {
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var dbcsCode = this.gb18030.gbChars[idx] + (uCode - this.gb18030.uChars[idx]);
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newBuf[j++] = 0x81 + Math.floor(dbcsCode / 12600); dbcsCode = dbcsCode % 12600;
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newBuf[j++] = 0x30 + Math.floor(dbcsCode / 1260); dbcsCode = dbcsCode % 1260;
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newBuf[j++] = 0x81 + Math.floor(dbcsCode / 10); dbcsCode = dbcsCode % 10;
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newBuf[j++] = 0x30 + dbcsCode;
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continue;
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}
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}
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}
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// 3. Write dbcsCode character.
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if (dbcsCode === UNASSIGNED)
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dbcsCode = this.defaultCharSingleByte;
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if (dbcsCode < 0x100) {
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newBuf[j++] = dbcsCode;
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}
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else if (dbcsCode < 0x10000) {
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newBuf[j++] = dbcsCode >> 8; // high byte
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newBuf[j++] = dbcsCode & 0xFF; // low byte
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}
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else {
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newBuf[j++] = dbcsCode >> 16;
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newBuf[j++] = (dbcsCode >> 8) & 0xFF;
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newBuf[j++] = dbcsCode & 0xFF;
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}
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}
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this.seqObj = seqObj;
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this.leadSurrogate = leadSurrogate;
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return newBuf.slice(0, j);
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}
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DBCSEncoder.prototype.end = function() {
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if (this.leadSurrogate === -1 && this.seqObj === undefined)
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return; // All clean. Most often case.
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var newBuf = Buffer.alloc(10), j = 0;
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if (this.seqObj) { // We're in the sequence.
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var dbcsCode = this.seqObj[DEF_CHAR];
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if (dbcsCode !== undefined) { // Write beginning of the sequence.
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if (dbcsCode < 0x100) {
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newBuf[j++] = dbcsCode;
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}
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else {
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newBuf[j++] = dbcsCode >> 8; // high byte
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newBuf[j++] = dbcsCode & 0xFF; // low byte
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}
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} else {
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// See todo above.
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}
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this.seqObj = undefined;
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}
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if (this.leadSurrogate !== -1) {
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// Incomplete surrogate pair - only lead surrogate found.
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newBuf[j++] = this.defaultCharSingleByte;
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this.leadSurrogate = -1;
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}
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return newBuf.slice(0, j);
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}
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// Export for testing
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DBCSEncoder.prototype.findIdx = findIdx;
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// == Decoder ==================================================================
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function DBCSDecoder(options, codec) {
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// Decoder state
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this.nodeIdx = 0;
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this.prevBuf = Buffer.alloc(0);
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// Static data
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this.decodeTables = codec.decodeTables;
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this.decodeTableSeq = codec.decodeTableSeq;
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this.defaultCharUnicode = codec.defaultCharUnicode;
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this.gb18030 = codec.gb18030;
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}
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DBCSDecoder.prototype.write = function(buf) {
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var newBuf = Buffer.alloc(buf.length*2),
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nodeIdx = this.nodeIdx,
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prevBuf = this.prevBuf, prevBufOffset = this.prevBuf.length,
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seqStart = -this.prevBuf.length, // idx of the start of current parsed sequence.
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uCode;
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if (prevBufOffset > 0) // Make prev buf overlap a little to make it easier to slice later.
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prevBuf = Buffer.concat([prevBuf, buf.slice(0, 10)]);
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for (var i = 0, j = 0; i < buf.length; i++) {
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var curByte = (i >= 0) ? buf[i] : prevBuf[i + prevBufOffset];
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// Lookup in current trie node.
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var uCode = this.decodeTables[nodeIdx][curByte];
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if (uCode >= 0) {
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// Normal character, just use it.
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}
|
|
else if (uCode === UNASSIGNED) { // Unknown char.
|
|
// TODO: Callback with seq.
|
|
//var curSeq = (seqStart >= 0) ? buf.slice(seqStart, i+1) : prevBuf.slice(seqStart + prevBufOffset, i+1 + prevBufOffset);
|
|
i = seqStart; // Try to parse again, after skipping first byte of the sequence ('i' will be incremented by 'for' cycle).
|
|
uCode = this.defaultCharUnicode.charCodeAt(0);
|
|
}
|
|
else if (uCode === GB18030_CODE) {
|
|
var curSeq = (seqStart >= 0) ? buf.slice(seqStart, i+1) : prevBuf.slice(seqStart + prevBufOffset, i+1 + prevBufOffset);
|
|
var ptr = (curSeq[0]-0x81)*12600 + (curSeq[1]-0x30)*1260 + (curSeq[2]-0x81)*10 + (curSeq[3]-0x30);
|
|
var idx = findIdx(this.gb18030.gbChars, ptr);
|
|
uCode = this.gb18030.uChars[idx] + ptr - this.gb18030.gbChars[idx];
|
|
}
|
|
else if (uCode <= NODE_START) { // Go to next trie node.
|
|
nodeIdx = NODE_START - uCode;
|
|
continue;
|
|
}
|
|
else if (uCode <= SEQ_START) { // Output a sequence of chars.
|
|
var seq = this.decodeTableSeq[SEQ_START - uCode];
|
|
for (var k = 0; k < seq.length - 1; k++) {
|
|
uCode = seq[k];
|
|
newBuf[j++] = uCode & 0xFF;
|
|
newBuf[j++] = uCode >> 8;
|
|
}
|
|
uCode = seq[seq.length-1];
|
|
}
|
|
else
|
|
throw new Error("iconv-lite internal error: invalid decoding table value " + uCode + " at " + nodeIdx + "/" + curByte);
|
|
|
|
// Write the character to buffer, handling higher planes using surrogate pair.
|
|
if (uCode > 0xFFFF) {
|
|
uCode -= 0x10000;
|
|
var uCodeLead = 0xD800 + Math.floor(uCode / 0x400);
|
|
newBuf[j++] = uCodeLead & 0xFF;
|
|
newBuf[j++] = uCodeLead >> 8;
|
|
|
|
uCode = 0xDC00 + uCode % 0x400;
|
|
}
|
|
newBuf[j++] = uCode & 0xFF;
|
|
newBuf[j++] = uCode >> 8;
|
|
|
|
// Reset trie node.
|
|
nodeIdx = 0; seqStart = i+1;
|
|
}
|
|
|
|
this.nodeIdx = nodeIdx;
|
|
this.prevBuf = (seqStart >= 0) ? buf.slice(seqStart) : prevBuf.slice(seqStart + prevBufOffset);
|
|
return newBuf.slice(0, j).toString('ucs2');
|
|
}
|
|
|
|
DBCSDecoder.prototype.end = function() {
|
|
var ret = '';
|
|
|
|
// Try to parse all remaining chars.
|
|
while (this.prevBuf.length > 0) {
|
|
// Skip 1 character in the buffer.
|
|
ret += this.defaultCharUnicode;
|
|
var buf = this.prevBuf.slice(1);
|
|
|
|
// Parse remaining as usual.
|
|
this.prevBuf = Buffer.alloc(0);
|
|
this.nodeIdx = 0;
|
|
if (buf.length > 0)
|
|
ret += this.write(buf);
|
|
}
|
|
|
|
this.nodeIdx = 0;
|
|
return ret;
|
|
}
|
|
|
|
// Binary search for GB18030. Returns largest i such that table[i] <= val.
|
|
function findIdx(table, val) {
|
|
if (table[0] > val)
|
|
return -1;
|
|
|
|
var l = 0, r = table.length;
|
|
while (l < r-1) { // always table[l] <= val < table[r]
|
|
var mid = l + Math.floor((r-l+1)/2);
|
|
if (table[mid] <= val)
|
|
l = mid;
|
|
else
|
|
r = mid;
|
|
}
|
|
return l;
|
|
}
|
|
|