lib/lz-string.js

// Copyright (c) 2013 Pieroxy <[email protected]>
// 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 1.3.3
var LZString = {
  
  
  // private property
  _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
  _f : String.fromCharCode,
  
  compressToBase64 : function (input) {
    if (input == null) return "";
    var output = "";
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
    var i = 0;
    
    input = LZString.compress(input);
    
    while (i < input.length*2) {
      
      if (i%2==0) {
        chr1 = input.charCodeAt(i/2) >> 8;
        chr2 = input.charCodeAt(i/2) & 255;
        if (i/2+1 < input.length) 
          chr3 = input.charCodeAt(i/2+1) >> 8;
        else 
          chr3 = NaN;
      } else {
        chr1 = input.charCodeAt((i-1)/2) & 255;
        if ((i+1)/2 < input.length) {
          chr2 = input.charCodeAt((i+1)/2) >> 8;
          chr3 = input.charCodeAt((i+1)/2) & 255;
        } else 
          chr2=chr3=NaN;
      }
      i+=3;
      
      enc1 = chr1 >> 2;
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
      enc4 = chr3 & 63;
      
      if (isNaN(chr2)) {
        enc3 = enc4 = 64;
      } else if (isNaN(chr3)) {
        enc4 = 64;
      }
      
      output = output +
        LZString._keyStr.charAt(enc1) + LZString._keyStr.charAt(enc2) +
          LZString._keyStr.charAt(enc3) + LZString._keyStr.charAt(enc4);
      
    }
    
    return output;
  },
  
  decompressFromBase64 : function (input) {
    if (input == null) return "";
    var output = "",
        ol = 0, 
        output_,
        chr1, chr2, chr3,
        enc1, enc2, enc3, enc4,
        i = 0, f=LZString._f;
    
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    
    while (i < input.length) {
      
      enc1 = LZString._keyStr.indexOf(input.charAt(i++));
      enc2 = LZString._keyStr.indexOf(input.charAt(i++));
      enc3 = LZString._keyStr.indexOf(input.charAt(i++));
      enc4 = LZString._keyStr.indexOf(input.charAt(i++));
      
      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;
      
      if (ol%2==0) {
        output_ = chr1 << 8;
        
        if (enc3 != 64) {
          output += f(output_ | chr2);
        }
        if (enc4 != 64) {
          output_ = chr3 << 8;
        }
      } else {
        output = output + f(output_ | chr1);
        
        if (enc3 != 64) {
          output_ = chr2 << 8;
        }
        if (enc4 != 64) {
          output += f(output_ | chr3);
        }
      }
      ol+=3;
    }
    
    return LZString.decompress(output);
    
  },

  compressToUTF16 : function (input) {
    if (input == null) return "";
    var output = "",
        i,c,
        current,
        status = 0,
        f = LZString._f;
    
    input = LZString.compress(input);
    
    for (i=0 ; i<input.length ; i++) {
      c = input.charCodeAt(i);
      switch (status++) {
        case 0:
          output += f((c >> 1)+32);
          current = (c & 1) << 14;
          break;
        case 1:
          output += f((current + (c >> 2))+32);
          current = (c & 3) << 13;
          break;
        case 2:
          output += f((current + (c >> 3))+32);
          current = (c & 7) << 12;
          break;
        case 3:
          output += f((current + (c >> 4))+32);
          current = (c & 15) << 11;
          break;
        case 4:
          output += f((current + (c >> 5))+32);
          current = (c & 31) << 10;
          break;
        case 5:
          output += f((current + (c >> 6))+32);
          current = (c & 63) << 9;
          break;
        case 6:
          output += f((current + (c >> 7))+32);
          current = (c & 127) << 8;
          break;
        case 7:
          output += f((current + (c >> 8))+32);
          current = (c & 255) << 7;
          break;
        case 8:
          output += f((current + (c >> 9))+32);
          current = (c & 511) << 6;
          break;
        case 9:
          output += f((current + (c >> 10))+32);
          current = (c & 1023) << 5;
          break;
        case 10:
          output += f((current + (c >> 11))+32);
          current = (c & 2047) << 4;
          break;
        case 11:
          output += f((current + (c >> 12))+32);
          current = (c & 4095) << 3;
          break;
        case 12:
          output += f((current + (c >> 13))+32);
          current = (c & 8191) << 2;
          break;
        case 13:
          output += f((current + (c >> 14))+32);
          current = (c & 16383) << 1;
          break;
        case 14:
          output += f((current + (c >> 15))+32, (c & 32767)+32);
          status = 0;
          break;
      }
    }
    
    return output + f(current + 32);
  },
  

  decompressFromUTF16 : function (input) {
    if (input == null) return "";
    var output = "",
        current,c,
        status=0,
        i = 0,
        f = LZString._f;
    
    while (i < input.length) {
      c = input.charCodeAt(i) - 32;
      
      switch (status++) {
        case 0:
          current = c << 1;
          break;
        case 1:
          output += f(current | (c >> 14));
          current = (c&16383) << 2;
          break;
        case 2:
          output += f(current | (c >> 13));
          current = (c&8191) << 3;
          break;
        case 3:
          output += f(current | (c >> 12));
          current = (c&4095) << 4;
          break;
        case 4:
          output += f(current | (c >> 11));
          current = (c&2047) << 5;
          break;
        case 5:
          output += f(current | (c >> 10));
          current = (c&1023) << 6;
          break;
        case 6:
          output += f(current | (c >> 9));
          current = (c&511) << 7;
          break;
        case 7:
          output += f(current | (c >> 8));
          current = (c&255) << 8;
          break;
        case 8:
          output += f(current | (c >> 7));
          current = (c&127) << 9;
          break;
        case 9:
          output += f(current | (c >> 6));
          current = (c&63) << 10;
          break;
        case 10:
          output += f(current | (c >> 5));
          current = (c&31) << 11;
          break;
        case 11:
          output += f(current | (c >> 4));
          current = (c&15) << 12;
          break;
        case 12:
          output += f(current | (c >> 3));
          current = (c&7) << 13;
          break;
        case 13:
          output += f(current | (c >> 2));
          current = (c&3) << 14;
          break;
        case 14:
          output += f(current | (c >> 1));
          current = (c&1) << 15;
          break;
        case 15:
          output += f(current | c);
          status=0;
          break;
      }
      
      
      i++;
    }
    
    return LZString.decompress(output);
    //return output;
    
  },


  
  compress: function (uncompressed) {
    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_string="", 
        context_data_val=0, 
        context_data_position=0,
        ii,
        f=LZString._f;
    
    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 == 15) {
                context_data_position = 0;
                context_data_string += f(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 == 15) {
                context_data_position = 0;
                context_data_string += f(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 == 15) {
                context_data_position = 0;
                context_data_string += f(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 == 15) {
                context_data_position = 0;
                context_data_string += f(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 == 15) {
              context_data_position = 0;
              context_data_string += f(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 == 15) {
              context_data_position = 0;
              context_data_string += f(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 == 15) {
              context_data_position = 0;
              context_data_string += f(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 == 15) {
              context_data_position = 0;
              context_data_string += f(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 == 15) {
              context_data_position = 0;
              context_data_string += f(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 == 15) {
            context_data_position = 0;
            context_data_string += f(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 == 15) {
        context_data_position = 0;
        context_data_string += f(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 == 15) {
        context_data_string += f(context_data_val);
        break;
      }
      else context_data_position++;
    }
    return context_data_string;
  },
  
  decompress: function (compressed) {
    if (compressed == null) return "";
    if (compressed == "") return null;
    var dictionary = [],
        next,
        enlargeIn = 4,
        dictSize = 4,
        numBits = 3,
        entry = "",
        result = "",
        i,
        w,
        bits, resb, maxpower, power,
        c,
        f = LZString._f,
        data = {string:compressed, val:compressed.charCodeAt(0), position:32768, 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 = 32768;
        data.val = data.string.charCodeAt(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 = 32768;
              data.val = data.string.charCodeAt(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 = 32768;
              data.val = data.string.charCodeAt(data.index++);
            }
            bits |= (resb>0 ? 1 : 0) * power;
            power <<= 1;
          }
        c = f(bits);
        break;
      case 2: 
        return "";
    }
    dictionary[3] = c;
    w = result = c;
    while (true) {
      if (data.index > data.string.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 = 32768;
          data.val = data.string.charCodeAt(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 = 32768;
              data.val = data.string.charCodeAt(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 = 32768;
              data.val = data.string.charCodeAt(data.index++);
            }
            bits |= (resb>0 ? 1 : 0) * power;
            power <<= 1;
          }
          dictionary[dictSize++] = f(bits);
          c = dictSize-1;
          enlargeIn--;
          break;
        case 2: 
          return result;
      }
      
      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 += 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++;
      }
      
    }
  }
};

if( typeof module !== 'undefined' && module != null ) {
  module.exports = LZString
}