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276 lines
7.9 KiB
276 lines
7.9 KiB
"use strict";
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var utils = require("./utils");
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var support = require("./support");
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var nodejsUtils = require("./nodejsUtils");
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var GenericWorker = require("./stream/GenericWorker");
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/**
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* The following functions come from pako, from pako/lib/utils/strings
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* released under the MIT license, see pako https://github.com/nodeca/pako/
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*/
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// Table with utf8 lengths (calculated by first byte of sequence)
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// Note, that 5 & 6-byte values and some 4-byte values can not be represented in JS,
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// because max possible codepoint is 0x10ffff
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var _utf8len = new Array(256);
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for (var i=0; i<256; i++) {
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_utf8len[i] = (i >= 252 ? 6 : i >= 248 ? 5 : i >= 240 ? 4 : i >= 224 ? 3 : i >= 192 ? 2 : 1);
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}
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_utf8len[254]=_utf8len[254]=1; // Invalid sequence start
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// convert string to array (typed, when possible)
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var string2buf = function (str) {
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var buf, c, c2, m_pos, i, str_len = str.length, buf_len = 0;
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// count binary size
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for (m_pos = 0; m_pos < str_len; m_pos++) {
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c = str.charCodeAt(m_pos);
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if ((c & 0xfc00) === 0xd800 && (m_pos+1 < str_len)) {
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c2 = str.charCodeAt(m_pos+1);
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if ((c2 & 0xfc00) === 0xdc00) {
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c = 0x10000 + ((c - 0xd800) << 10) + (c2 - 0xdc00);
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m_pos++;
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}
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}
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buf_len += c < 0x80 ? 1 : c < 0x800 ? 2 : c < 0x10000 ? 3 : 4;
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}
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// allocate buffer
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if (support.uint8array) {
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buf = new Uint8Array(buf_len);
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} else {
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buf = new Array(buf_len);
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}
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// convert
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for (i=0, m_pos = 0; i < buf_len; m_pos++) {
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c = str.charCodeAt(m_pos);
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if ((c & 0xfc00) === 0xd800 && (m_pos+1 < str_len)) {
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c2 = str.charCodeAt(m_pos+1);
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if ((c2 & 0xfc00) === 0xdc00) {
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c = 0x10000 + ((c - 0xd800) << 10) + (c2 - 0xdc00);
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m_pos++;
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}
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}
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if (c < 0x80) {
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/* one byte */
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buf[i++] = c;
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} else if (c < 0x800) {
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/* two bytes */
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buf[i++] = 0xC0 | (c >>> 6);
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buf[i++] = 0x80 | (c & 0x3f);
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} else if (c < 0x10000) {
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/* three bytes */
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buf[i++] = 0xE0 | (c >>> 12);
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buf[i++] = 0x80 | (c >>> 6 & 0x3f);
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buf[i++] = 0x80 | (c & 0x3f);
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} else {
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/* four bytes */
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buf[i++] = 0xf0 | (c >>> 18);
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buf[i++] = 0x80 | (c >>> 12 & 0x3f);
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buf[i++] = 0x80 | (c >>> 6 & 0x3f);
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buf[i++] = 0x80 | (c & 0x3f);
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}
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}
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return buf;
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};
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// Calculate max possible position in utf8 buffer,
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// that will not break sequence. If that's not possible
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// - (very small limits) return max size as is.
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//
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// buf[] - utf8 bytes array
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// max - length limit (mandatory);
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var utf8border = function(buf, max) {
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var pos;
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max = max || buf.length;
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if (max > buf.length) { max = buf.length; }
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// go back from last position, until start of sequence found
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pos = max-1;
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while (pos >= 0 && (buf[pos] & 0xC0) === 0x80) { pos--; }
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// Fuckup - very small and broken sequence,
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// return max, because we should return something anyway.
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if (pos < 0) { return max; }
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// If we came to start of buffer - that means vuffer is too small,
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// return max too.
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if (pos === 0) { return max; }
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return (pos + _utf8len[buf[pos]] > max) ? pos : max;
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};
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// convert array to string
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var buf2string = function (buf) {
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var i, out, c, c_len;
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var len = buf.length;
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// Reserve max possible length (2 words per char)
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// NB: by unknown reasons, Array is significantly faster for
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// String.fromCharCode.apply than Uint16Array.
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var utf16buf = new Array(len*2);
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for (out=0, i=0; i<len;) {
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c = buf[i++];
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// quick process ascii
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if (c < 0x80) { utf16buf[out++] = c; continue; }
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c_len = _utf8len[c];
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// skip 5 & 6 byte codes
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if (c_len > 4) { utf16buf[out++] = 0xfffd; i += c_len-1; continue; }
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// apply mask on first byte
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c &= c_len === 2 ? 0x1f : c_len === 3 ? 0x0f : 0x07;
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// join the rest
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while (c_len > 1 && i < len) {
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c = (c << 6) | (buf[i++] & 0x3f);
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c_len--;
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}
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// terminated by end of string?
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if (c_len > 1) { utf16buf[out++] = 0xfffd; continue; }
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if (c < 0x10000) {
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utf16buf[out++] = c;
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} else {
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c -= 0x10000;
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utf16buf[out++] = 0xd800 | ((c >> 10) & 0x3ff);
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utf16buf[out++] = 0xdc00 | (c & 0x3ff);
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}
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}
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// shrinkBuf(utf16buf, out)
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if (utf16buf.length !== out) {
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if(utf16buf.subarray) {
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utf16buf = utf16buf.subarray(0, out);
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} else {
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utf16buf.length = out;
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}
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}
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// return String.fromCharCode.apply(null, utf16buf);
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return utils.applyFromCharCode(utf16buf);
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};
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// That's all for the pako functions.
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/**
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* Transform a javascript string into an array (typed if possible) of bytes,
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* UTF-8 encoded.
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* @param {String} str the string to encode
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* @return {Array|Uint8Array|Buffer} the UTF-8 encoded string.
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*/
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exports.utf8encode = function utf8encode(str) {
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if (support.nodebuffer) {
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return nodejsUtils.newBufferFrom(str, "utf-8");
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}
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return string2buf(str);
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};
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/**
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* Transform a bytes array (or a representation) representing an UTF-8 encoded
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* string into a javascript string.
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* @param {Array|Uint8Array|Buffer} buf the data de decode
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* @return {String} the decoded string.
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*/
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exports.utf8decode = function utf8decode(buf) {
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if (support.nodebuffer) {
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return utils.transformTo("nodebuffer", buf).toString("utf-8");
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}
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buf = utils.transformTo(support.uint8array ? "uint8array" : "array", buf);
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return buf2string(buf);
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};
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/**
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* A worker to decode utf8 encoded binary chunks into string chunks.
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* @constructor
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*/
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function Utf8DecodeWorker() {
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GenericWorker.call(this, "utf-8 decode");
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// the last bytes if a chunk didn't end with a complete codepoint.
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this.leftOver = null;
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}
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utils.inherits(Utf8DecodeWorker, GenericWorker);
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/**
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* @see GenericWorker.processChunk
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*/
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Utf8DecodeWorker.prototype.processChunk = function (chunk) {
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var data = utils.transformTo(support.uint8array ? "uint8array" : "array", chunk.data);
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// 1st step, re-use what's left of the previous chunk
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if (this.leftOver && this.leftOver.length) {
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if(support.uint8array) {
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var previousData = data;
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data = new Uint8Array(previousData.length + this.leftOver.length);
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data.set(this.leftOver, 0);
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data.set(previousData, this.leftOver.length);
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} else {
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data = this.leftOver.concat(data);
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}
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this.leftOver = null;
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}
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var nextBoundary = utf8border(data);
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var usableData = data;
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if (nextBoundary !== data.length) {
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if (support.uint8array) {
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usableData = data.subarray(0, nextBoundary);
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this.leftOver = data.subarray(nextBoundary, data.length);
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} else {
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usableData = data.slice(0, nextBoundary);
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this.leftOver = data.slice(nextBoundary, data.length);
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}
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}
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this.push({
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data : exports.utf8decode(usableData),
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meta : chunk.meta
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});
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};
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/**
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* @see GenericWorker.flush
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*/
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Utf8DecodeWorker.prototype.flush = function () {
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if(this.leftOver && this.leftOver.length) {
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this.push({
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data : exports.utf8decode(this.leftOver),
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meta : {}
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});
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this.leftOver = null;
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}
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};
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exports.Utf8DecodeWorker = Utf8DecodeWorker;
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/**
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* A worker to endcode string chunks into utf8 encoded binary chunks.
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* @constructor
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*/
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function Utf8EncodeWorker() {
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GenericWorker.call(this, "utf-8 encode");
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}
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utils.inherits(Utf8EncodeWorker, GenericWorker);
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/**
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* @see GenericWorker.processChunk
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*/
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Utf8EncodeWorker.prototype.processChunk = function (chunk) {
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this.push({
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data : exports.utf8encode(chunk.data),
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meta : chunk.meta
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});
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};
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exports.Utf8EncodeWorker = Utf8EncodeWorker;
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