Procedural File: CompressStr.php

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Copyright (c) 2006-2016 Khaled Al-Sham'aa.

http://www.ar-php.org

PHP Version 5

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LICENSE

This program is open source product; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License (LGPL) as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/lgpl.txt>.

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Class Name: Compress string using Huffman-like coding

Filename: CompressStr.php

Original Author(s): Khaled Al-Sham'aa <khaled@ar-php.org>

Purpose: This class will compress given string in binary format using variable-length code table (derived in a particular way based on the estimated probability of occurrence for each possible value of the source symbol) for encoding a source symbol

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Arabic Compress String Class

Compress string using Huffman-like coding

This class compresses text strings into roughly 70% of their original size by benefit from using compact coding for most frequented letters in a given language. This algorithm associated with text language, so you will find 6 different classes for the following languages: Arabic, English, French, German, Italian and Spanish language.

Benefits of this compress algorithm include:

• It is written in pure PHP code, so there is no need to any PHP extensions to use it.
• You can search in compressed string directly without any need uncompress text before search in.
• You can get original string length directly without need to uncompress compressed text.

There is another drawback, this algorithm working only on text from a given language, it does not working fine on binary files like images or PDF.

Example:

1.  include('./I18N/Arabic.php');
2.  $obj = new I18N_Arabic('CompressStr');
3.  
4.  $obj->setInputCharset('windows-1256');
5.  $obj->setOutputCharset('windows-1256');
6.  
7.  $file = 'Compress/ar_example.txt';
8.  $fh   = fopen($file, 'r');
9.  $str  = fread($fh, filesize($file));
10.  fclose($fh);
11.  
12.  $zip = $obj->compress($str);
13.  
14.  $before = strlen($str);
15.  $after  = strlen($zip);
16.  $rate   = round($after * 100 / $before);
17.  
18.  echo "String size before was: $before Byte<br>";
19.  echo "Compressed string size after is: $after Byte<br>";
20.  echo "Rate $rate %<hr>";
21.  
22.  $str = $obj->decompress($zip);
23.  
24.  if ($obj->search($zip, $word)) {
25.      echo "Search for $word in zipped string and find it<hr>";
26.  } else {
27.      echo "Search for $word in zipped string and do not find it<hr>";
28.  }
29.  
30.  $len = $obj->length($zip);
31.  echo "Original length of zipped string is $len Byte<hr>";
32.  
33.  echo '<div dir="rtl" align="justify">'.nl2br($str).'</div>';

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