Decoder::checkDictionaryCompliance() - Code Metrics - Inspection of "Added support for encoding objects that extend a s..." - s9e/Bencode - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 2c49eb...da29c3 )

by Josh

created 2020-11-16 20:46 UTC

Decoder::checkDictionaryCompliance() A

↳ Parent: Decoder

Complexity

Conditions	3
Paths	3

Size

Total Lines	9
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	2
CRAP Score	3

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	3
eloc	4
nc	3
nop	3
dl	0
loc	9
ccs	2
cts	2
cp	1
crap	3
rs	10
c	1
b	0
f	0

<?php declare(strict_types=1);

/**
* @package   s9e\Bencode
* @copyright Copyright (c) 2014-2020 The s9e authors
* @license   http://www.opensource.org/licenses/mit-license.php The MIT License
*/
namespace s9e\Bencode;

use ArrayObject;
use s9e\Bencode\Exceptions\ComplianceError;
use s9e\Bencode\Exceptions\DecodingException;

class Decoder
{
	/**
	* @var string Bencoded string being decoded
	*/
	protected string $bencoded;

	/**
	* @var int Length of the bencoded string
	*/
	protected int $len;

	/**
	* @var int Safe rightmost boundary
	*/
	protected int $max;

	/**
	* @var int Position of the cursor while decoding
	*/
	protected int $offset;

	public static function decode(string $bencoded)
	{
		$decoder = new static($bencoded);
		$value   = $decoder->decodeAnything();

		$decoder->checkCursorPosition();

		return $value;
	}

	protected function __construct(string $bencoded)
	{
		$this->bencoded = $bencoded;
		$this->len      = strlen($bencoded);
		$this->offset   = 0;

		if ($bencoded === '')
		{
			throw new DecodingException('Premature end of data', 0);
		}
		$this->computeSafeBoundary();
	}

	protected function checkBoundary(): void
	{
		if ($this->max < 1)
		{
			if (strpos('-e', $this->bencoded[0]) !== false)
			{
				throw new DecodingException('Illegal character', 0);
			}

			throw new DecodingException('Premature end of data', $this->len - 1);
		}
	}

	/**
	* Check the cursor's position after decoding is done
	*/
	protected function checkCursorPosition(): void
	{
		if ($this->offset !== $this->len)
		{
			if ($this->offset > $this->len)
			{
				throw new DecodingException('Premature end of data', $this->len - 1);
			}

			$this->complianceError('Superfluous content', $this->offset);
		}
	}

	protected function checkDictionaryCompliance(int $offset, string $key, ?string $lastKey): void
	{
		if ($key === $lastKey)
		{
			$this->complianceError("Duplicate dictionary entry '" . $key . "'", $offset);
		}
		elseif ($key < $lastKey)
		{
			$this->complianceError("Out of order dictionary entry '" . $key . "'", $offset);
		}
	}

	protected function complianceError(string $message, int $offset): void
	{
		throw new ComplianceError($message, $offset);
	}

	/**
	* Adjust the rightmost boundary to the last safe character that can start a value
	*
	* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
	*/
	protected function computeSafeBoundary(): void
	{
		$boundary = $this->len - 1;
		$c = $this->bencoded[$boundary];
		while (is_numeric($c) && --$boundary >= 0)
		{
			$c = $this->bencoded[$boundary];
		}
		if ($c === '-')
		{
			$boundary -= 2;
		}
		elseif ($c === 'i')
		{
			--$boundary;
		}

		$this->max = $boundary;
		$this->checkBoundary();
	}

	protected function decodeAnything()
	{
		$c = $this->bencoded[$this->offset];
		if ($c === 'i')
		{
			return $this->decodeInteger();
		}
		if ($c === 'd')
		{
			return $this->decodeDictionary();
		}
		if ($c === 'l')
		{
			return $this->decodeList();
		}

		return $this->decodeString();
	}

	protected function decodeDictionary(): ArrayObject
	{
		$values  = [];
		$lastKey = null;

		++$this->offset;
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
			}

			$offset = $this->offset;
			$key    = $this->decodeString();
			if ($key <= $lastKey)
			{
				$this->checkDictionaryCompliance($offset, $key, $lastKey);
			}
			if ($this->offset > $this->max)
			{
				break;
			}
			$values[$key] = $this->decodeAnything();
			$lastKey      = $key;
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeDigits(string $terminator): int
	{
		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
		$spn = strspn($this->bencoded, '4615302879', $this->offset);
		if (!$spn)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		if ($this->bencoded[$this->offset] === '0' && $spn > 1)
		{
			$this->complianceError('Illegal character', 1 + $this->offset);
		}

		// Capture the value and cast it as an integer
		$value = (int) substr($this->bencoded, $this->offset, $spn);

		$this->offset += $spn;
		if ($this->bencoded[$this->offset] !== $terminator)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		++$this->offset;

		return $value;
	}

	protected function decodeInteger(): int
	{
		$negative = ($this->bencoded[++$this->offset] === '-');
		if ($negative && $this->bencoded[++$this->offset] === '0')
		{
			$this->complianceError('Illegal character', $this->offset);
		}

		$value = $this->decodeDigits('e');

		return ($negative) ? -$value : $value;
	}

	protected function decodeList(): array
	{
		++$this->offset;

		$list = [];
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return $list;
			}

			$list[] = $this->decodeAnything();
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeString(): string
	{
		$len           = $this->decodeDigits(':');
		$string        = substr($this->bencoded, $this->offset, $len);
		$this->offset += $len;

		return $string;
	}
}

1		<?php declare(strict_types=1);
2
3		/**
4		* @package s9e\Bencode
5		* @copyright Copyright (c) 2014-2020 The s9e authors
6		* @license http://www.opensource.org/licenses/mit-license.php The MIT License
7		*/
8		namespace s9e\Bencode;
9
10		use ArrayObject;
11		use s9e\Bencode\Exceptions\ComplianceError;
12		use s9e\Bencode\Exceptions\DecodingException;
13
14		class Decoder
15		{
16		/**
17		* @var string Bencoded string being decoded
18		*/
19		protected string $bencoded;
20
21		/**
22		* @var int Length of the bencoded string
23		*/
24		protected int $len;
25
26		/**
27		* @var int Safe rightmost boundary
28		*/
29		protected int $max;
30
31		/**
32		* @var int Position of the cursor while decoding
33		*/
34		protected int $offset;
35
36	61	public static function decode(string $bencoded)
37		{
38	61	$decoder = new static($bencoded);
39	50	$value = $decoder->decodeAnything();
40
41	26	$decoder->checkCursorPosition();
42
43	18	return $value;
44		}
45
46	61	protected function __construct(string $bencoded)
47		{
48	61	$this->bencoded = $bencoded;
49	61	$this->len = strlen($bencoded);
50	61	$this->offset = 0;
51
52	61	if ($bencoded === '')
53		{
54	1	throw new DecodingException('Premature end of data', 0);
55		}
56	60	$this->computeSafeBoundary();
57		}
58
59	60	protected function checkBoundary(): void
60		{
61	60	if ($this->max < 1)
62		{
63	10	if (strpos('-e', $this->bencoded[0]) !== false)
64		{
65	2	throw new DecodingException('Illegal character', 0);
66		}
67
68	8	throw new DecodingException('Premature end of data', $this->len - 1);
69		}
70		}
71
72		/**
73		* Check the cursor's position after decoding is done
74		*/
75	26	protected function checkCursorPosition(): void
76		{
77	26	if ($this->offset !== $this->len)
78		{
79	8	if ($this->offset > $this->len)
80		{
81	3	throw new DecodingException('Premature end of data', $this->len - 1);
82		}
83
84	5	$this->complianceError('Superfluous content', $this->offset);
85		}
86		}
87
88	12	protected function checkDictionaryCompliance(int $offset, string $key, ?string $lastKey): void
89		{
90	12	if ($key === $lastKey)
91		{
92		$this->complianceError("Duplicate dictionary entry '" . $key . "'", $offset);
93		}
94		elseif ($key < $lastKey)
95		{
96		$this->complianceError("Out of order dictionary entry '" . $key . "'", $offset);
97		}
98	60	}
99
100	60	protected function complianceError(string $message, int $offset): void
101	60	{
102	60	throw new ComplianceError($message, $offset);
103		}
104	7
105		/**
106	60	* Adjust the rightmost boundary to the last safe character that can start a value
107		*
108	6	* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
109		*/
110	54	protected function computeSafeBoundary(): void
111		{
112	6	$boundary = $this->len - 1;
113		$c = $this->bencoded[$boundary];
114		while (is_numeric($c) && --$boundary >= 0)
115	60	{
116	60	$c = $this->bencoded[$boundary];
117		}
118		if ($c === '-')
119	50	{
120		$boundary -= 2;
121	50	}
122	50	elseif ($c === 'i')
123		{
124	17	--$boundary;
125		}
126	41
127		$this->max = $boundary;
128	15	$this->checkBoundary();
129		}
130	32
131		protected function decodeAnything()
132	12	{
133		$c = $this->bencoded[$this->offset];
134		if ($c === 'i')
135	25	{
136		return $this->decodeInteger();
137		}
138	15	if ($c === 'd')
139		{
140	15	return $this->decodeDictionary();
141	15	}
142		if ($c === 'l')
143	15	{
144	15	return $this->decodeList();
145		}
146	15
147		return $this->decodeString();
148	7	}
149
150	7	protected function decodeDictionary(): ArrayObject
151		{
152		$values = [];
153	14	$lastKey = null;
154	14
155	13	++$this->offset;
156		while ($this->offset <= $this->max)
157	4	{
158		if ($this->bencoded[$this->offset] === 'e')
159	13	{
160		++$this->offset;
161	1
162		return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
163	12	}
164	9
165		$offset = $this->offset;
166		$key = $this->decodeString();
167	1	if ($key <= $lastKey)
168		{
169		$this->checkDictionaryCompliance($offset, $key, $lastKey);
170	43	}
171		if ($this->offset > $this->max)
172		{
173	43	break;
174	43	}
175		$values[$key] = $this->decodeAnything();
176	7	$lastKey = $key;
177		}
178	38
179		throw new DecodingException('Premature end of data', $this->len - 1);
180	3	}
181
182		protected function decodeDigits(string $terminator): int
183		{
184	35	// Digits sorted by decreasing frequency as observed on a random sample of torrent files
185		$spn = strspn($this->bencoded, '4615302879', $this->offset);
186	35	if (!$spn)
187	35	{
188		throw new DecodingException('Illegal character', $this->offset);
189	5	}
190		if ($this->bencoded[$this->offset] === '0' && $spn > 1)
191	30	{
192		$this->complianceError('Illegal character', 1 + $this->offset);
193	30	}
194
195		// Capture the value and cast it as an integer
196	17	$value = (int) substr($this->bencoded, $this->offset, $spn);
197
198	17	$this->offset += $spn;
199	17	if ($this->bencoded[$this->offset] !== $terminator)
200		{
201	1	throw new DecodingException('Illegal character', $this->offset);
202		}
203		++$this->offset;
204	16
205		return $value;
206	11	}
207
208		protected function decodeInteger(): int
209	12	{
210		$negative = ($this->bencoded[++$this->offset] === '-');
211	12	if ($negative && $this->bencoded[++$this->offset] === '0')
212		{
213	12	$this->complianceError('Illegal character', $this->offset);
214	12	}
215
216	11	$value = $this->decodeDigits('e');
217
218	7	return ($negative) ? -$value : $value;
219		}
220	7
221		protected function decodeList(): array
222		{
223	8	++$this->offset;
224
225		$list = [];
226	4	while ($this->offset <= $this->max)
227		{
228		if ($this->bencoded[$this->offset] === 'e')
229	34	{
230		++$this->offset;
231	34
232	26	return $list;
233	26	}
234
235	26	$list[] = $this->decodeAnything();
236		}
237
238	4	throw new DecodingException('Premature end of data', $this->len - 1);
239		}
240	4
241		protected function decodeString(): string
242	2	{
243		$len = $this->decodeDigits(':');
244	2	$string = substr($this->bencoded, $this->offset, $len);
245		$this->offset += $len;
246	1
247		return $string;
248		}
249		}

s9e / Bencode

Push — master ( 2c49eb...da29c3 )

Decoder::checkDictionaryCompliance() A

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