168 lines
3.7 KiB
JavaScript
168 lines
3.7 KiB
JavaScript
function BinaryString(source) {
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this._source = null;
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this._bytes = [];
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this._pos = 0;
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this._length = 0;
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this._init = function(source) {
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this._source = source;
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this._bytes = this._stringToBytes(this._source);
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this._length = this._bytes.length;
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}
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this.current = function() {return this._pos;}
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this.rewind = function() {return this.jump(0);}
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this.end = function() {return this.jump(this.length() - 1);}
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this.next = function() {return this.jump(this.current() + 1);}
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this.prev = function() {return this.jump(this.current() - 1);}
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this.jump = function(pos) {
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if (pos < 0 || pos >= this.length()) return false;
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this._pos = pos;
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return true;
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}
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this.readByte = function(pos) {
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pos = (typeof pos == 'number') ? pos : this.current();
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return this.readBytes(1, pos)[0];
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}
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this.readBytes = function(length, pos) {
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length = length || 1;
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pos = (typeof pos == 'number') ? pos : this.current();
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if (pos > this.length() ||
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pos < 0 ||
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length <= 0 ||
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pos + length > this.length() ||
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pos + length < 0
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) {
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return false;
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}
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var bytes = [];
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for (var i = pos; i < pos + length; i++) {
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bytes.push(this._bytes[i]);
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}
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return bytes;
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}
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this.length = function() {return this._length;}
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this.toString = function() {
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var string = '',
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length = this.length();
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for (var i = 0; i < length; i++) {
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string += String.fromCharCode(this.readByte(i));
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}
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return string;
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}
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this.toUtf8 = function() {
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var inc = 0,
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string = '',
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length = this.length();
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// determine if first 3 characters are the BOM
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// then skip them in output if so
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if (length >= 3 &&
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this.readByte(0) === 0xEF &&
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this.readByte(1) === 0xBB &&
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this.readByte(2) === 0xBF
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) {
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inc = 3;
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}
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for (; inc < length; inc++) {
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var byte1 = this.readByte(inc),
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byte2 = 0,
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byte3 = 0,
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byte4 = 0,
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code1 = 0,
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code2 = 0,
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point = 0;
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switch (true) {
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// single byte character; same as ascii
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case (byte1 < 0x80):
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code1 = byte1;
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break;
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// 2 byte character
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case (byte1 >= 0xC2 && byte1 < 0xE0):
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byte2 = this.readByte(++inc);
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code1 = ((byte1 & 0x1F) << 6) +
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(byte2 & 0x3F);
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break;
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// 3 byte character
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case (byte1 >= 0xE0 && byte1 < 0xF0):
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byte2 = this.readByte(++inc);
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byte3 = this.readByte(++inc);
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code1 = ((byte1 & 0xFF) << 12) +
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((byte2 & 0x3F) << 6) +
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(byte3 & 0x3F);
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break;
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// 4 byte character
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case (byte1 >= 0xF0 && byte1 < 0xF5):
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byte2 = this.readByte(++inc);
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byte3 = this.readByte(++inc);
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byte4 = this.readByte(++inc);
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point = ((byte1 & 0x07) << 18) +
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((byte2 & 0x3F) << 12) +
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((byte3 & 0x3F) << 6) +
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(byte4 & 0x3F)
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point -= 0x10000;
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code1 = (point >> 10) + 0xD800;
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code2 = (point & 0x3FF) + 0xDC00;
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break;
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default:
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throw 'Invalid byte ' + this._byteToString(byte1) + ' whilst converting to UTF-8';
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break;
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}
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string += (code2) ? String.fromCharCode(code1, code2)
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: String.fromCharCode(code1);
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}
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return string;
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}
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this.toArray = function() {return this.readBytes(this.length() - 1, 0);}
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this._stringToBytes = function(str) {
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var bytes = [],
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chr = 0;
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for (var i = 0; i < str.length; i++) {
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chr = str.charCodeAt(i);
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bytes.push(chr & 0xFF);
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}
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return bytes;
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}
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this._byteToString = function(byte) {
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var asString = byte.toString(16).toUpperCase();
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while (asString.length < 2) {
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asString = '0' + asString;
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}
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return '0x' + asString;
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}
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this._init(source);
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}
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