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Commit 117f41be authored by rswindell's avatar rswindell
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Handy data compression library from https://github.com/pieroxy/lz-string

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// Copyright (c) 2013 Pieroxy <pieroxy@pieroxy.net>
// This work is free. You can redistribute it and/or modify it
// under the terms of the WTFPL, Version 2
// For more information see LICENSE.txt or http://www.wtfpl.net/
//
// For more information, the home page:
// http://pieroxy.net/blog/pages/lz-string/testing.html
//
// LZ-based compression algorithm, version 1.4.4
var LZString = (function() {
// private property
var f = String.fromCharCode;
var keyStrBase64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var keyStrUriSafe = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-$";
var baseReverseDic = {};
function getBaseValue(alphabet, character) {
if (!baseReverseDic[alphabet]) {
baseReverseDic[alphabet] = {};
for (var i=0 ; i<alphabet.length ; i++) {
baseReverseDic[alphabet][alphabet.charAt(i)] = i;
}
}
return baseReverseDic[alphabet][character];
}
var LZString = {
compressToBase64 : function (input) {
if (input == null) return "";
var res = LZString._compress(input, 6, function(a){return keyStrBase64.charAt(a);});
switch (res.length % 4) { // To produce valid Base64
default: // When could this happen ?
case 0 : return res;
case 1 : return res+"===";
case 2 : return res+"==";
case 3 : return res+"=";
}
},
decompressFromBase64 : function (input) {
if (input == null) return "";
if (input == "") return null;
return LZString._decompress(input.length, 32, function(index) { return getBaseValue(keyStrBase64, input.charAt(index)); });
},
compressToUTF16 : function (input) {
if (input == null) return "";
return LZString._compress(input, 15, function(a){return f(a+32);}) + " ";
},
decompressFromUTF16: function (compressed) {
if (compressed == null) return "";
if (compressed == "") return null;
return LZString._decompress(compressed.length, 16384, function(index) { return compressed.charCodeAt(index) - 32; });
},
//compress into uint8array (UCS-2 big endian format)
compressToUint8Array: function (uncompressed) {
var compressed = LZString.compress(uncompressed);
var buf=new Uint8Array(compressed.length*2); // 2 bytes per character
for (var i=0, TotalLen=compressed.length; i<TotalLen; i++) {
var current_value = compressed.charCodeAt(i);
buf[i*2] = current_value >>> 8;
buf[i*2+1] = current_value % 256;
}
return buf;
},
//decompress from uint8array (UCS-2 big endian format)
decompressFromUint8Array:function (compressed) {
if (compressed===null || compressed===undefined){
return LZString.decompress(compressed);
} else {
var buf=new Array(compressed.length/2); // 2 bytes per character
for (var i=0, TotalLen=buf.length; i<TotalLen; i++) {
buf[i]=compressed[i*2]*256+compressed[i*2+1];
}
var result = [];
buf.forEach(function (c) {
result.push(f(c));
});
return LZString.decompress(result.join(''));
}
},
//compress into a string that is already URI encoded
compressToEncodedURIComponent: function (input) {
if (input == null) return "";
return LZString._compress(input, 6, function(a){return keyStrUriSafe.charAt(a);});
},
//decompress from an output of compressToEncodedURIComponent
decompressFromEncodedURIComponent:function (input) {
if (input == null) return "";
if (input == "") return null;
input = input.replace(/ /g, "+");
return LZString._decompress(input.length, 32, function(index) { return getBaseValue(keyStrUriSafe, input.charAt(index)); });
},
compress: function (uncompressed) {
return LZString._compress(uncompressed, 16, function(a){return f(a);});
},
_compress: function (uncompressed, bitsPerChar, getCharFromInt) {
if (uncompressed == null) return "";
var i, value,
context_dictionary= {},
context_dictionaryToCreate= {},
context_c="",
context_wc="",
context_w="",
context_enlargeIn= 2, // Compensate for the first entry which should not count
context_dictSize= 3,
context_numBits= 2,
context_data=[],
context_data_val=0,
context_data_position=0,
ii;
for (ii = 0; ii < uncompressed.length; ii += 1) {
context_c = uncompressed.charAt(ii);
if (!Object.prototype.hasOwnProperty.call(context_dictionary,context_c)) {
context_dictionary[context_c] = context_dictSize++;
context_dictionaryToCreate[context_c] = true;
}
context_wc = context_w + context_c;
if (Object.prototype.hasOwnProperty.call(context_dictionary,context_wc)) {
context_w = context_wc;
} else {
if (Object.prototype.hasOwnProperty.call(context_dictionaryToCreate,context_w)) {
if (context_w.charCodeAt(0)<256) {
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
}
value = context_w.charCodeAt(0);
for (i=0 ; i<8 ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
} else {
value = 1;
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1) | value;
if (context_data_position ==bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = 0;
}
value = context_w.charCodeAt(0);
for (i=0 ; i<16 ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
}
context_enlargeIn--;
if (context_enlargeIn == 0) {
context_enlargeIn = Math.pow(2, context_numBits);
context_numBits++;
}
delete context_dictionaryToCreate[context_w];
} else {
value = context_dictionary[context_w];
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
}
context_enlargeIn--;
if (context_enlargeIn == 0) {
context_enlargeIn = Math.pow(2, context_numBits);
context_numBits++;
}
// Add wc to the dictionary.
context_dictionary[context_wc] = context_dictSize++;
context_w = String(context_c);
}
}
// Output the code for w.
if (context_w !== "") {
if (Object.prototype.hasOwnProperty.call(context_dictionaryToCreate,context_w)) {
if (context_w.charCodeAt(0)<256) {
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
}
value = context_w.charCodeAt(0);
for (i=0 ; i<8 ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
} else {
value = 1;
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1) | value;
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = 0;
}
value = context_w.charCodeAt(0);
for (i=0 ; i<16 ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
}
context_enlargeIn--;
if (context_enlargeIn == 0) {
context_enlargeIn = Math.pow(2, context_numBits);
context_numBits++;
}
delete context_dictionaryToCreate[context_w];
} else {
value = context_dictionary[context_w];
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
}
context_enlargeIn--;
if (context_enlargeIn == 0) {
context_enlargeIn = Math.pow(2, context_numBits);
context_numBits++;
}
}
// Mark the end of the stream
value = 2;
for (i=0 ; i<context_numBits ; i++) {
context_data_val = (context_data_val << 1) | (value&1);
if (context_data_position == bitsPerChar-1) {
context_data_position = 0;
context_data.push(getCharFromInt(context_data_val));
context_data_val = 0;
} else {
context_data_position++;
}
value = value >> 1;
}
// Flush the last char
while (true) {
context_data_val = (context_data_val << 1);
if (context_data_position == bitsPerChar-1) {
context_data.push(getCharFromInt(context_data_val));
break;
}
else context_data_position++;
}
return context_data.join('');
},
decompress: function (compressed) {
if (compressed == null) return "";
if (compressed == "") return null;
return LZString._decompress(compressed.length, 32768, function(index) { return compressed.charCodeAt(index); });
},
_decompress: function (length, resetValue, getNextValue) {
var dictionary = [],
next,
enlargeIn = 4,
dictSize = 4,
numBits = 3,
entry = "",
result = [],
i,
w,
bits, resb, maxpower, power,
c,
data = {val:getNextValue(0), position:resetValue, index:1};
for (i = 0; i < 3; i += 1) {
dictionary[i] = i;
}
bits = 0;
maxpower = Math.pow(2,2);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
switch (next = bits) {
case 0:
bits = 0;
maxpower = Math.pow(2,8);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
c = f(bits);
break;
case 1:
bits = 0;
maxpower = Math.pow(2,16);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
c = f(bits);
break;
case 2:
return "";
}
dictionary[3] = c;
w = c;
result.push(c);
while (true) {
if (data.index > length) {
return "";
}
bits = 0;
maxpower = Math.pow(2,numBits);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
switch (c = bits) {
case 0:
bits = 0;
maxpower = Math.pow(2,8);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
dictionary[dictSize++] = f(bits);
c = dictSize-1;
enlargeIn--;
break;
case 1:
bits = 0;
maxpower = Math.pow(2,16);
power=1;
while (power!=maxpower) {
resb = data.val & data.position;
data.position >>= 1;
if (data.position == 0) {
data.position = resetValue;
data.val = getNextValue(data.index++);
}
bits |= (resb>0 ? 1 : 0) * power;
power <<= 1;
}
dictionary[dictSize++] = f(bits);
c = dictSize-1;
enlargeIn--;
break;
case 2:
return result.join('');
}
if (enlargeIn == 0) {
enlargeIn = Math.pow(2, numBits);
numBits++;
}
if (dictionary[c]) {
entry = dictionary[c];
} else {
if (c === dictSize) {
entry = w + w.charAt(0);
} else {
return null;
}
}
result.push(entry);
// Add w+entry[0] to the dictionary.
dictionary[dictSize++] = w + entry.charAt(0);
enlargeIn--;
w = entry;
if (enlargeIn == 0) {
enlargeIn = Math.pow(2, numBits);
numBits++;
}
}
}
};
return LZString;
})();
if (typeof define === 'function' && define.amd) {
define(function () { return LZString; });
} else if( typeof module !== 'undefined' && module != null ) {
module.exports = LZString
} else if( typeof angular !== 'undefined' && angular != null ) {
angular.module('LZString', [])
.factory('LZString', function () {
return LZString;
});
}
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