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