Qvitter/js/lib/lz-string.js

/*

@licstart  The following is the entire license notice for the
JavaScript code in this page.

DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004

Copyright (c) 2013 Pieroxy <pieroxy@pieroxy.net> http://pieroxy.net/blog/pages/lz-string/testing.html

Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.

WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

0. You just DO WHAT THE FUCK YOU WANT TO.

@licend  The above is the entire license notice
for the JavaScript code in this page.

*/

// 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;
})();