320 lines
9.7 KiB
JavaScript
320 lines
9.7 KiB
JavaScript
'use strict';
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var Buffer = require('safer-buffer').Buffer;
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// == UTF32-LE/BE codec. ==========================================================
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exports._utf32 = Utf32Codec;
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function Utf32Codec(codecOptions, iconv) {
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this.iconv = iconv;
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this.bomAware = true;
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this.isLE = codecOptions.isLE;
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}
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exports.utf32le = { type: '_utf32', isLE: true };
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exports.utf32be = { type: '_utf32', isLE: false };
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// Aliases
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exports.ucs4le = 'utf32le';
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exports.ucs4be = 'utf32be';
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Utf32Codec.prototype.encoder = Utf32Encoder;
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Utf32Codec.prototype.decoder = Utf32Decoder;
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// -- Encoding
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function Utf32Encoder(options, codec) {
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this.isLE = codec.isLE;
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this.highSurrogate = 0;
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}
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Utf32Encoder.prototype.write = function(str) {
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var src = Buffer.from(str, 'ucs2');
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var dst = Buffer.alloc(src.length * 2);
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var write32 = this.isLE ? dst.writeUInt32LE : dst.writeUInt32BE;
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var offset = 0;
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for (var i = 0; i < src.length; i += 2) {
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var code = src.readUInt16LE(i);
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var isHighSurrogate = (0xD800 <= code && code < 0xDC00);
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var isLowSurrogate = (0xDC00 <= code && code < 0xE000);
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if (this.highSurrogate) {
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if (isHighSurrogate || !isLowSurrogate) {
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// There shouldn't be two high surrogates in a row, nor a high surrogate which isn't followed by a low
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// surrogate. If this happens, keep the pending high surrogate as a stand-alone semi-invalid character
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// (technically wrong, but expected by some applications, like Windows file names).
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write32.call(dst, this.highSurrogate, offset);
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offset += 4;
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}
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else {
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// Create 32-bit value from high and low surrogates;
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var codepoint = (((this.highSurrogate - 0xD800) << 10) | (code - 0xDC00)) + 0x10000;
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write32.call(dst, codepoint, offset);
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offset += 4;
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this.highSurrogate = 0;
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continue;
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}
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}
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if (isHighSurrogate)
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this.highSurrogate = code;
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else {
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// Even if the current character is a low surrogate, with no previous high surrogate, we'll
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// encode it as a semi-invalid stand-alone character for the same reasons expressed above for
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// unpaired high surrogates.
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write32.call(dst, code, offset);
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offset += 4;
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this.highSurrogate = 0;
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}
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}
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if (offset < dst.length)
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dst = dst.slice(0, offset);
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return dst;
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};
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Utf32Encoder.prototype.end = function() {
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// Treat any leftover high surrogate as a semi-valid independent character.
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if (!this.highSurrogate)
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return;
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var buf = Buffer.alloc(4);
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if (this.isLE)
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buf.writeUInt32LE(this.highSurrogate, 0);
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else
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buf.writeUInt32BE(this.highSurrogate, 0);
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this.highSurrogate = 0;
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return buf;
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};
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// -- Decoding
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function Utf32Decoder(options, codec) {
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this.isLE = codec.isLE;
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this.badChar = codec.iconv.defaultCharUnicode.charCodeAt(0);
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this.overflow = [];
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}
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Utf32Decoder.prototype.write = function(src) {
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if (src.length === 0)
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return '';
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var i = 0;
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var codepoint = 0;
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var dst = Buffer.alloc(src.length + 4);
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var offset = 0;
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var isLE = this.isLE;
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var overflow = this.overflow;
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var badChar = this.badChar;
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if (overflow.length > 0) {
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for (; i < src.length && overflow.length < 4; i++)
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overflow.push(src[i]);
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if (overflow.length === 4) {
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// NOTE: codepoint is a signed int32 and can be negative.
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// NOTE: We copied this block from below to help V8 optimize it (it works with array, not buffer).
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if (isLE) {
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codepoint = overflow[i] | (overflow[i+1] << 8) | (overflow[i+2] << 16) | (overflow[i+3] << 24);
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} else {
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codepoint = overflow[i+3] | (overflow[i+2] << 8) | (overflow[i+1] << 16) | (overflow[i] << 24);
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}
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overflow.length = 0;
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offset = _writeCodepoint(dst, offset, codepoint, badChar);
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}
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}
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// Main loop. Should be as optimized as possible.
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for (; i < src.length - 3; i += 4) {
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// NOTE: codepoint is a signed int32 and can be negative.
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if (isLE) {
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codepoint = src[i] | (src[i+1] << 8) | (src[i+2] << 16) | (src[i+3] << 24);
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} else {
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codepoint = src[i+3] | (src[i+2] << 8) | (src[i+1] << 16) | (src[i] << 24);
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}
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offset = _writeCodepoint(dst, offset, codepoint, badChar);
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}
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// Keep overflowing bytes.
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for (; i < src.length; i++) {
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overflow.push(src[i]);
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}
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return dst.slice(0, offset).toString('ucs2');
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};
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function _writeCodepoint(dst, offset, codepoint, badChar) {
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// NOTE: codepoint is signed int32 and can be negative. We keep it that way to help V8 with optimizations.
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if (codepoint < 0 || codepoint > 0x10FFFF) {
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// Not a valid Unicode codepoint
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codepoint = badChar;
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}
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// Ephemeral Planes: Write high surrogate.
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if (codepoint >= 0x10000) {
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codepoint -= 0x10000;
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var high = 0xD800 | (codepoint >> 10);
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dst[offset++] = high & 0xff;
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dst[offset++] = high >> 8;
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// Low surrogate is written below.
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var codepoint = 0xDC00 | (codepoint & 0x3FF);
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}
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// Write BMP char or low surrogate.
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dst[offset++] = codepoint & 0xff;
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dst[offset++] = codepoint >> 8;
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return offset;
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};
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Utf32Decoder.prototype.end = function() {
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this.overflow.length = 0;
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};
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// == UTF-32 Auto codec =============================================================
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// Decoder chooses automatically from UTF-32LE and UTF-32BE using BOM and space-based heuristic.
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// Defaults to UTF-32LE. http://en.wikipedia.org/wiki/UTF-32
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// Encoder/decoder default can be changed: iconv.decode(buf, 'utf32', {defaultEncoding: 'utf-32be'});
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// Encoder prepends BOM (which can be overridden with (addBOM: false}).
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exports.utf32 = Utf32AutoCodec;
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exports.ucs4 = 'utf32';
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function Utf32AutoCodec(options, iconv) {
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this.iconv = iconv;
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}
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Utf32AutoCodec.prototype.encoder = Utf32AutoEncoder;
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Utf32AutoCodec.prototype.decoder = Utf32AutoDecoder;
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// -- Encoding
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function Utf32AutoEncoder(options, codec) {
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options = options || {};
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if (options.addBOM === undefined)
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options.addBOM = true;
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this.encoder = codec.iconv.getEncoder(options.defaultEncoding || 'utf-32le', options);
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}
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Utf32AutoEncoder.prototype.write = function(str) {
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return this.encoder.write(str);
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};
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Utf32AutoEncoder.prototype.end = function() {
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return this.encoder.end();
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};
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// -- Decoding
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function Utf32AutoDecoder(options, codec) {
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this.decoder = null;
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this.initialBufs = [];
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this.initialBufsLen = 0;
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this.options = options || {};
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this.iconv = codec.iconv;
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}
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Utf32AutoDecoder.prototype.write = function(buf) {
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if (!this.decoder) {
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// Codec is not chosen yet. Accumulate initial bytes.
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this.initialBufs.push(buf);
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this.initialBufsLen += buf.length;
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if (this.initialBufsLen < 32) // We need more bytes to use space heuristic (see below)
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return '';
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// We have enough bytes -> detect endianness.
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var encoding = detectEncoding(this.initialBufs, this.options.defaultEncoding);
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this.decoder = this.iconv.getDecoder(encoding, this.options);
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var resStr = '';
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for (var i = 0; i < this.initialBufs.length; i++)
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resStr += this.decoder.write(this.initialBufs[i]);
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this.initialBufs.length = this.initialBufsLen = 0;
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return resStr;
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}
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return this.decoder.write(buf);
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};
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Utf32AutoDecoder.prototype.end = function() {
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if (!this.decoder) {
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var encoding = detectEncoding(this.initialBufs, this.options.defaultEncoding);
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this.decoder = this.iconv.getDecoder(encoding, this.options);
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var resStr = '';
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for (var i = 0; i < this.initialBufs.length; i++)
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resStr += this.decoder.write(this.initialBufs[i]);
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var trail = this.decoder.end();
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if (trail)
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resStr += trail;
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this.initialBufs.length = this.initialBufsLen = 0;
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return resStr;
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}
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return this.decoder.end();
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};
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function detectEncoding(bufs, defaultEncoding) {
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var b = [];
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var charsProcessed = 0;
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var invalidLE = 0, invalidBE = 0; // Number of invalid chars when decoded as LE or BE.
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var bmpCharsLE = 0, bmpCharsBE = 0; // Number of BMP chars when decoded as LE or BE.
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outer_loop:
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for (var i = 0; i < bufs.length; i++) {
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var buf = bufs[i];
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for (var j = 0; j < buf.length; j++) {
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b.push(buf[j]);
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if (b.length === 4) {
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if (charsProcessed === 0) {
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// Check BOM first.
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if (b[0] === 0xFF && b[1] === 0xFE && b[2] === 0 && b[3] === 0) {
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return 'utf-32le';
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}
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if (b[0] === 0 && b[1] === 0 && b[2] === 0xFE && b[3] === 0xFF) {
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return 'utf-32be';
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}
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}
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if (b[0] !== 0 || b[1] > 0x10) invalidBE++;
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if (b[3] !== 0 || b[2] > 0x10) invalidLE++;
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if (b[0] === 0 && b[1] === 0 && (b[2] !== 0 || b[3] !== 0)) bmpCharsBE++;
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if ((b[0] !== 0 || b[1] !== 0) && b[2] === 0 && b[3] === 0) bmpCharsLE++;
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b.length = 0;
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charsProcessed++;
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if (charsProcessed >= 100) {
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break outer_loop;
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}
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}
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}
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}
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// Make decisions.
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if (bmpCharsBE - invalidBE > bmpCharsLE - invalidLE) return 'utf-32be';
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if (bmpCharsBE - invalidBE < bmpCharsLE - invalidLE) return 'utf-32le';
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// Couldn't decide (likely all zeros or not enough data).
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return defaultEncoding || 'utf-32le';
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}
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