"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;
}
