Huffman::unpackDictionary() - Code Metrics - Inspection of "Merge remote-tracking branch 'origin/huffman'" - mmeyer2k/dcrypt - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 968cc5...a69343 )

by Michael

created 2017-09-14 08:18 UTC

Huffman::unpackDictionary() A

↳ Parent: Huffman

Complexity

Conditions	2
Paths	2

Size

Total Lines	17
Code Lines	9

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
dl	0
loc	17
rs	9.4285
c	0
b	0
f	0
cc	2
eloc	9
nc	2
nop	1

<?php

/**
 * Huffman.php
 * 
 * PHP version 5
 * 
 * @category Dcrypt
 * @package  Dcrypt
 * @author   Michael Meyer (mmeyer2k) <[email protected]>
 * @license  http://opensource.org/licenses/MIT The MIT License (MIT)
 * @link     https://github.com/mmeyer2k/dcrypt
 */

namespace Dcrypt;

/**
 * Huffman compression functions.
 *
 * @category Dcrypt
 * @package  Dcrypt
 * @author   Michael Meyer (mmeyer2k) <[email protected]>
 * @license  http://opensource.org/licenses/MIT The MIT License (MIT)
 * @link     https://github.com/mmeyer2k/dcrypt
 * @link     https://apigen.ci/github/mmeyer2k/dcrypt/namespace-Dcrypt.html
 */
final class Huffman
{

    /**
     * Compress data
     *
     * @param string $data
     * @return string
     */
    public static function encode($data)
    {
        $dictionary = self::frequencyMap($data);

        $binaryString = '';

        $indexMap = self::createBinaryIndexes(count($dictionary));

        // Map the binary data to the index
        foreach (str_split($data) as $d) {
            // Find character position in dictionary array
            $pos = array_search(base64_encode($d), array_keys($dictionary));

            // Append the binary to the running string
            $binaryString = $binaryString . $indexMap[$pos];
        }

        // Pad the string to the byte boundry
        while (strlen($binaryString) % 8 !== 0) {
            $binaryString = $binaryString . '0';
        }

        // Chunk data into bytes
        $chunks = str_split($binaryString, 8);

        // Pack the binary string
        foreach ($chunks as $i => &$chunk) {
            $padded = str_pad($chunk, 8, '0', STR_PAD_RIGHT);
            $chunk = chr(bindec($padded));
$a = "a";
$ab = "ab";
$abc = "abc";
        }

        // Return compressed data with packed dictionary
        return self::packDictionary($dictionary) . implode($chunks);
    }

    /**
     * Decompress data
     *
     * @param string $data
     * @return string
     */
    public static function decode($data)
    {
        $dictionary = self::unpackDictionary($data);

        // Remove dictionary bytes from beginning of data
        $data = str_split(substr($data, count($dictionary) * 2 + 1));

        $binary = '';

        // Convert data to binary
        while ($data) {

            $b = decbin(ord(array_shift($data)));

            // Pad to the left with zeros
            $b = str_pad($b, 8, '0', STR_PAD_LEFT);

            $binary .= $b;
        }

        $binary = str_split($binary);

        $pop = '';
        $out = '';

        while ($binary) {

            $pop .= array_shift($binary);
            if (isset($dictionary[$pop])) {
                $out .= $dictionary[$pop];
                $pop = '';
$a = "a";
$ab = "ab";
$abc = "abc";
            }
        }

        return $out;
    }

    /**
     * Creates a packed dictionary.
     *
     * @param array $dictionary
     * @return string
     */
    private static function packDictionary(array $dictionary)
    {
        // First byte will be the count of items in the dictionary
        $out = chr(count($dictionary));

        // Get the binary index mapping
        $indexMap = self::createBinaryIndexTree(count($dictionary));


        $dictionary = array_keys($dictionary);

        foreach ($dictionary as $idx => $char) {
            $out = $out . chr(bindec($indexMap[$idx])) . base64_decode($char);
        }

        return $out;
    }

    /**
     * Unpack dictionary
     *
     * @param $data
     * @return array
     */
    private static function unpackDictionary($data)
    {
        // Get first byte which is dictionary size
        $count = ord(substr($data, 0, 1));
$a = "a";
$ab = "ab";
$abc = "abc";
        $packedBytes = str_split(substr($data, 1, $count * 2));

        $out = [];

        while ($packedBytes) {

            $idx = array_shift($packedBytes);
            $val = array_shift($packedBytes);

            $out[decbin(ord($idx))] = $val;
        }

        return $out;
    }

    /**
     * Returns a bit mapping array like this:
     *
     * 100
     * 101
     * 111
     *
     * @param $count
     * @return array
     */
    private static function createBinaryIndexes($count)
    {
        // Start a counter to base our binary frame on
        $startOffset = 0;

        // Start a loop that we will manually break out of
        while (1) {
            $out = array();

            foreach (range(1, $count) as $range) {
                $out[] = decbin($startOffset + $range);
            }

            // Make sure that no index is the prefix of any another
            $found = false;
            foreach ($out as $v1) {
                foreach ($out as $v2) {
                    if ($v1 !== $v2 && starts_with($v1, $v2)) {
                        $found = true;
                    }
                }
            }

            // Once a mapping is accepted, return it as an array
            if (!$found) {
                return $out;
            }

            // ... otherwise, try again from the next highest position
            $startOffset = $startOffset + 1;
        }
    }

    /**
     * Map character frequency as array. Returns array like this:
     *
     * array(
     * 
     * )
     *
     * @param string $data
     * @return array
     */
    private static function frequencyMap($data)
    {
        $occurences = array();

        while (isset($data[0])) {
            // Count occurences for the first char and add to frequency map
            $occurences[base64_encode($data[0])] = substr_count($data, $data[0]);

            $data = str_replace($data[0], '', $data);
        }

        // Sort the resulting array
        asort($occurences);

        // Return the array in descending order
        return array_reverse($occurences);
    }
}


1			<?php
2
3			/**
4			* Huffman.php
5			*
6			* PHP version 5
7			*
8			* @category Dcrypt
9			* @package Dcrypt
10			* @author Michael Meyer (mmeyer2k) <[email protected]>
11			* @license http://opensource.org/licenses/MIT The MIT License (MIT)
12			* @link https://github.com/mmeyer2k/dcrypt
13			*/
14
15			namespace Dcrypt;
16
17			/**
18			* Huffman compression functions.
19			*
20			* @category Dcrypt
21			* @package Dcrypt
22			* @author Michael Meyer (mmeyer2k) <[email protected]>
23			* @license http://opensource.org/licenses/MIT The MIT License (MIT)
24			* @link https://github.com/mmeyer2k/dcrypt
25			* @link https://apigen.ci/github/mmeyer2k/dcrypt/namespace-Dcrypt.html
26			*/
27			final class Huffman
28			{
29
30			/**
31			* Compress data
32			*
33			* @param string $data
34			* @return string
35			*/
36			public static function encode($data)
37			{
38			$dictionary = self::frequencyMap($data);
39
40			$binaryString = '';
41
42			$indexMap = self::createBinaryIndexes(count($dictionary));
43
44			// Map the binary data to the index
45			foreach (str_split($data) as $d) {
46			// Find character position in dictionary array
47			$pos = array_search(base64_encode($d), array_keys($dictionary));
48
49			// Append the binary to the running string
50			$binaryString = $binaryString . $indexMap[$pos];
51			}
52
53			// Pad the string to the byte boundry
54			while (strlen($binaryString) % 8 !== 0) {
55			$binaryString = $binaryString . '0';
56			}
57
58			// Chunk data into bytes
59			$chunks = str_split($binaryString, 8);
60
61			// Pack the binary string
62			foreach ($chunks as $i => &$chunk) {
63			$padded = str_pad($chunk, 8, '0', STR_PAD_RIGHT);
64			$chunk = chr(bindec($padded));
			0 ignored issues – show Coding Style introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report Equals sign not aligned with surrounding assignments; expected 2 spaces but found 1 space This check looks for multiple assignments in successive lines of code. It will report an issue if the operators are not in a straight line. To visualize $a = "a"; $ab = "ab"; $abc = "abc"; will produce issues in the first and second line, while this second example $a = "a"; $ab = "ab"; $abc = "abc"; will produce no issues. Loading history...
65			}
66
67			// Return compressed data with packed dictionary
68			return self::packDictionary($dictionary) . implode($chunks);
69			}
70
71			/**
72			* Decompress data
73			*
74			* @param string $data
75			* @return string
76			*/
77			public static function decode($data)
78			{
79			$dictionary = self::unpackDictionary($data);
80
81			// Remove dictionary bytes from beginning of data
82			$data = str_split(substr($data, count($dictionary) * 2 + 1));
83
84			$binary = '';
85
86			// Convert data to binary
87			while ($data) {
			0 ignored issues – show Bug Best Practice introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report The expression `$data` of type `array` is implicitly converted to a boolean; are you sure this is intended? If so, consider using `! empty($expr)` instead to make it clear that you intend to check for an array without elements. This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent. Consider making the comparison explicit by using `empty(..)` or `! empty(...)` instead. Loading history...
88			$b = decbin(ord(array_shift($data)));
89
90			// Pad to the left with zeros
91			$b = str_pad($b, 8, '0', STR_PAD_LEFT);
92
93			$binary .= $b;
94			}
95
96			$binary = str_split($binary);
97
98			$pop = '';
99			$out = '';
100
101			while ($binary) {
			0 ignored issues – show Bug Best Practice introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report The expression `$binary` of type `array` is implicitly converted to a boolean; are you sure this is intended? If so, consider using `! empty($expr)` instead to make it clear that you intend to check for an array without elements. This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent. Consider making the comparison explicit by using `empty(..)` or `! empty(...)` instead. Loading history...
102			$pop .= array_shift($binary);
103			if (isset($dictionary[$pop])) {
104			$out .= $dictionary[$pop];
105			$pop = '';
			0 ignored issues – show Coding Style introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report Equals sign not aligned with surrounding assignments; expected 2 spaces but found 1 space This check looks for multiple assignments in successive lines of code. It will report an issue if the operators are not in a straight line. To visualize $a = "a"; $ab = "ab"; $abc = "abc"; will produce issues in the first and second line, while this second example $a = "a"; $ab = "ab"; $abc = "abc"; will produce no issues. Loading history...
106			}
107			}
108
109			return $out;
110			}
111
112			/**
113			* Creates a packed dictionary.
114			*
115			* @param array $dictionary
116			* @return string
117			*/
118			private static function packDictionary(array $dictionary)
119			{
120			// First byte will be the count of items in the dictionary
121			$out = chr(count($dictionary));
122
123			// Get the binary index mapping
124			$indexMap = self::createBinaryIndexTree(count($dictionary));
			0 ignored issues – show Bug introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report The method `createBinaryIndexTree()` does not exist on `Dcrypt\Huffman`. Did you maybe mean `createBinaryIndexes()`? This check marks calls to methods that do not seem to exist on an object. This is most likely the result of a method being renamed without all references to it being renamed likewise. Loading history...
125
126			$dictionary = array_keys($dictionary);
127
128			foreach ($dictionary as $idx => $char) {
129			$out = $out . chr(bindec($indexMap[$idx])) . base64_decode($char);
130			}
131
132			return $out;
133			}
134
135			/**
136			* Unpack dictionary
137			*
138			* @param $data
139			* @return array
140			*/
141			private static function unpackDictionary($data)
142			{
143			// Get first byte which is dictionary size
144			$count = ord(substr($data, 0, 1));
			0 ignored issues – show Coding Style introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report Equals sign not aligned with surrounding assignments; expected 7 spaces but found 1 space This check looks for multiple assignments in successive lines of code. It will report an issue if the operators are not in a straight line. To visualize $a = "a"; $ab = "ab"; $abc = "abc"; will produce issues in the first and second line, while this second example $a = "a"; $ab = "ab"; $abc = "abc"; will produce no issues. Loading history...
145			$packedBytes = str_split(substr($data, 1, $count * 2));
146
147			$out = [];
148
149			while ($packedBytes) {
			0 ignored issues – show Bug Best Practice introduced 2017-09-14 08:20 UTC by Report Bug Copy Issue Report The expression `$packedBytes` of type `array` is implicitly converted to a boolean; are you sure this is intended? If so, consider using `! empty($expr)` instead to make it clear that you intend to check for an array without elements. This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent. Consider making the comparison explicit by using `empty(..)` or `! empty(...)` instead. Loading history...
150			$idx = array_shift($packedBytes);
151			$val = array_shift($packedBytes);
152
153			$out[decbin(ord($idx))] = $val;
154			}
155
156			return $out;
157			}
158
159			/**
160			* Returns a bit mapping array like this:
161			*
162			* 100
163			* 101
164			* 111
165			*
166			* @param $count
167			* @return array
168			*/
169			private static function createBinaryIndexes($count)
170			{
171			// Start a counter to base our binary frame on
172			$startOffset = 0;
173
174			// Start a loop that we will manually break out of
175			while (1) {
176			$out = array();
177
178			foreach (range(1, $count) as $range) {
179			$out[] = decbin($startOffset + $range);
180			}
181
182			// Make sure that no index is the prefix of any another
183			$found = false;
184			foreach ($out as $v1) {
185			foreach ($out as $v2) {
186			if ($v1 !== $v2 && starts_with($v1, $v2)) {
187			$found = true;
188			}
189			}
190			}
191
192			// Once a mapping is accepted, return it as an array
193			if (!$found) {
194			return $out;
195			}
196
197			// ... otherwise, try again from the next highest position
198			$startOffset = $startOffset + 1;
199			}
200			}
201
202			/**
203			* Map character frequency as array. Returns array like this:
204			*
205			* array(
206			*
207			* )
208			*
209			* @param string $data
210			* @return array
211			*/
212			private static function frequencyMap($data)
213			{
214			$occurences = array();
215
216			while (isset($data[0])) {
217			// Count occurences for the first char and add to frequency map
218			$occurences[base64_encode($data[0])] = substr_count($data, $data[0]);
219
220			$data = str_replace($data[0], '', $data);
221			}
222
223			// Sort the resulting array
224			asort($occurences);
225
226			// Return the array in descending order
227			return array_reverse($occurences);
228			}
229			}
230

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Huffman::unpackDictionary() A

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