https://eindtoetsmedicatieveiligheid.netlify.app/lib/lzwcompress.js

1/*
2 * lzwCompress.js
3 *
4 * Copyright (c) 2012-2016 floydpink
5 * Licensed under the MIT license.
6 *
7 * The MIT License (MIT)
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a copy
10 * of this software and associated documentation files (the "Software"), to deal
11 * in the Software without restriction, including without limitation the rights
12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the Software is
14 * furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included in all
17 * copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25 * SOFTWARE.
26 */
27
28'use strict';
29
30(function () {
31  var root = this;
32
33  var lzwCompress = (function (Array, JSON, undefined) {
34    var _self = {},
35        _lzwLoggingEnabled = false,
36        _lzwLog = function (message) {
37          try {
38            console.log('lzwCompress: ' +
39              (new Date()).toISOString() + ' : ' + (typeof(message) === 'object' ? JSON.stringify(message) : message));
40          } catch (e) {
41          }
42        };
43
44    // KeyOptimize
45    // http://stackoverflow.com/questions/4433402/replace-keys-json-in-javascript
46    (function (self, Array, JSON) {
47
48      var _keys = [],
49          comparer = function (key) {
50            return function (e) {
51              return e === key;
52            };
53          },
54          inArray = function (array,comparer) {
55            for (var i = 0; i < array.length; i++) {
56              if (comparer(array[i])) {
57                return true;
58              }
59            }
60            return false;
61          },
62          pushNew = function (array,element, comparer) {
63            if (!inArray(array,comparer)) {
64              array.push(element);
65            }
66          },
67          _extractKeys = function (obj) {
68            if (typeof obj === 'object') {
69              for (var key in obj) {
70                if (!Array.isArray(obj)) {
71                  pushNew(_keys,key, comparer(key));
72                }
73                _extractKeys(obj[key]);
74              }
75            }
76          },
77          _encode = function (obj) {
78            if (typeof obj !== 'object') {
79              return obj;
80            }
81            for (var prop in obj) {
82              if (!Array.isArray(obj)) {
83                if (obj.hasOwnProperty(prop)) {
84                  obj[_keys.indexOf(prop)] = _encode(obj[prop]);
85                  delete obj[prop];
86                }
87              } else {
88                obj[prop] = _encode(obj[prop]);
89              }
90            }
91            return obj;
92          },
93          _decode = function (obj) {
94            if (typeof obj !== 'object') {
95              return obj;
96            }
97            for (var prop in obj) {
98              if (!Array.isArray(obj)) {
99                if (obj.hasOwnProperty(prop) && _keys[prop]) {
100                  obj[_keys[prop]] = _decode(obj[prop]);
101                  delete obj[prop];
102                }
103              } else {
104                obj[prop] = _decode(obj[prop]);
105              }
106            }
107            return obj;
108          },
109          compress = function (json) {
110            _keys = [];
111            var jsonObj = JSON.parse(json);
112            _extractKeys(jsonObj);
113            _lzwLoggingEnabled && _lzwLog('keys length : ' + _keys.length);
114            _lzwLoggingEnabled && _lzwLog('keys        : ' + _keys);
115            return JSON.stringify({ __k : _keys, __v : _encode(jsonObj) });
116          },
117          decompress = function (minifiedJson) {
118            var obj = minifiedJson;
119            if (typeof(obj) !== 'object') {
120              return minifiedJson;
121            }
122            if (!obj.hasOwnProperty('__k')) {
123              return JSON.stringify(obj);
124            }
125            _keys = obj.__k;
126            return _decode(obj.__v);
127          };
128
129      self.KeyOptimize = {
130        pack   : compress,
131        unpack : decompress
132      };
133    }(_self, Array, JSON));
134
135    // LZWCompress
136    // http://stackoverflow.com/a/2252533/218882
137    // http://rosettacode.org/wiki/LZW_compression#JavaScript
138    (function (self, Array) {
139      var compress = function (uncompressed) {
140            if (typeof(uncompressed) !== 'string') {
141              return uncompressed;
142            }
143            var i,
144                dictionary = {},
145                c,
146                wc,
147                w = '',
148                result = [],
149                dictSize = 256;
150            for (i = 0; i < 256; i += 1) {
151              dictionary[String.fromCharCode(i)] = i;
152            }
153            for (i = 0; i < uncompressed.length; i += 1) {
154              c = uncompressed.charAt(i);
155              wc = w + c;
156              if (dictionary[wc]) {
157                w = wc;
158              } else {
159                if (dictionary[w] === undefined) {
160                  return uncompressed;
161                }
162                result.push(dictionary[w]);
163                dictionary[wc] = dictSize++;
164                w = String(c);
165              }
166            }
167            if (w !== '') {
168              result.push(dictionary[w]);
169            }
170            return result;
171          },
172          decompress = function (compressed) {
173            if (!Array.isArray(compressed)) {
174              return compressed;
175            }
176            var i,
177                dictionary = [],
178                w,
179                result,
180                k,
181                entry = '',
182                dictSize = 256;
183            for (i = 0; i < 256; i += 1) {
184              dictionary[i] = String.fromCharCode(i);
185            }
186            w = String.fromCharCode(compressed[0]);
187            result = w;
188            for (i = 1; i < compressed.length; i += 1) {
189              k = compressed[i];
190              if (dictionary[k]) {
191                entry = dictionary[k];
192              } else {
193                if (k === dictSize) {
194                  entry = w + w.charAt(0);
195                } else {
196                  return null;
197                }
198              }
199              result += entry;
200              dictionary[dictSize++] = w + entry.charAt(0);
201              w = entry;
202            }
203            return result;
204          };
205
206      self.LZWCompress = {
207        pack   : compress,
208        unpack : decompress
209      };
210    }(_self, Array));
211
212    var _compress = function (obj) {
213          _lzwLoggingEnabled && _lzwLog('original (uncompressed) : ' + obj);
214          if (!obj || obj === true || obj instanceof Date) {
215            return obj;
216          }
217          var result = obj;
218          if (typeof obj === 'object') {
219            result = _self.KeyOptimize.pack(JSON.stringify(obj));
220            _lzwLoggingEnabled && _lzwLog('key optimized: ' + result);
221          }
222          var packedObj = _self.LZWCompress.pack(result);
223          _lzwLoggingEnabled && _lzwLog('packed   (compressed)   : ' + packedObj);
224          return packedObj;
225        },
226        _decompress = function (compressedObj) {
227          _lzwLoggingEnabled && _lzwLog('original (compressed)   : ' + compressedObj);
228          if (!compressedObj || compressedObj === true || compressedObj instanceof Date) {
229            return compressedObj;
230          }
231          var probableJSON, result = _self.LZWCompress.unpack(compressedObj);
232          try {
233            probableJSON = JSON.parse(result);
234          } catch (e) {
235            _lzwLoggingEnabled && _lzwLog('unpacked (uncompressed) : ' + result);
236            return result;
237          }
238          if (typeof probableJSON === 'object') {
239            result = _self.KeyOptimize.unpack(probableJSON);
240          }
241          _lzwLoggingEnabled && _lzwLog('unpacked (uncompressed) : ' + result);
242          return result;
243        },
244        _enableLogging = function (enable) {
245          _lzwLoggingEnabled = enable;
246        };
247
248    return {
249      pack          : _compress,
250      unpack        : _decompress,
251      enableLogging : _enableLogging
252    };
253
254  })(Array, JSON);
255
256  if (typeof module !== 'undefined' && module.exports) {
257    module.exports = lzwCompress;
258  }
259  else {
260    root.lzwCompress = lzwCompress;
261  }
262
263}).call(this);