Decoder::checkCursorPosition() - Code Metrics - Inspection of "41168939300bdeae2bcfb378af8e9637f9f597dc" - s9e/Bencode - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Branch — master (411689)

by Josh

created 2020-08-30 17:09 UTC

Decoder::checkCursorPosition() A

↳ Parent: Decoder

Complexity

Conditions	3
Paths	3

Size

Total Lines	10
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	5
CRAP Score	3

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	3
eloc	4
c	1
b	0
f	0
nc	3
nop	0
dl	0
loc	10
ccs	5
cts	5
cp	1
crap	3
rs	10

<?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 InvalidArgumentException;
use RuntimeException;

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 $pos;

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

		$decoder->checkCursorPosition();

		return $value;
	}

	protected function __construct(string $bencoded)
	{
		if ($bencoded === '')
		{
			throw new InvalidArgumentException;
		}

		$this->bencoded = $bencoded;
		$this->len      = strlen($bencoded);
		$this->pos      = 0;

		$this->computeSafeBoundary();
	}

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

			throw new RuntimeException('Premature end of data');
		}
	}

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

			$this->complianceError('Superfluous content found at offset ' . $this->pos);
		}
	}

	protected function complianceError(string $message): void
	{
		throw new RuntimeException($message);
	}

	/**
	* 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->pos];
		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
	{
		$dictionary = new ArrayObject;
		$dictionary->setFlags(ArrayObject::ARRAY_AS_PROPS);

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

				return $dictionary;
			}

			$pos = $this->pos;
			$key = $this->decodeString();
			if (isset($dictionary->$key))
			{
				$this->complianceError("Duplicate dictionary entry '" . $key . "' at pos " . $pos);
			}
			if ($this->pos > $this->max)
			{
				break;
			}
			$dictionary->$key = $this->decodeAnything();
		}

		throw new RuntimeException('Premature end of data');
	}

	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', $this->pos);
		if (!$spn)
		{
			throw new RuntimeException('Illegal character found at offset ' . $this->pos);
		}
		if ($this->bencoded[$this->pos] === '0' && $spn > 1)
		{
			$this->complianceError('Illegal character found at offset ' . (1 + $this->pos));
		}

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

		$this->pos += $spn;
		if ($this->bencoded[$this->pos] !== $terminator)
		{
			throw new RuntimeException('Illegal character found at offset ' . $this->pos);
		}
		++$this->pos;

		return $value;
	}

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

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

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

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

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

				return $list;
			}

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

		throw new RuntimeException('Premature end of data');
	}

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

s9e / Bencode

Branch — master (411689)

Decoder::checkCursorPosition() A

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Size

Duplication

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