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

Passed

Push — DictionaryOrder ( d89a7c )

by Josh

created 2020-09-01 10:46 UTC

Decoder::dictionaryError() A

↳ Parent: Decoder

Complexity

Conditions	3
Paths	3

Size

Total Lines	9
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	5
CRAP Score	3

Importance

Changes

Metric	Value
cc	3
eloc	4
c	0
b	0
f	0
nc	3
nop	3
dl	0
loc	9
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
	{
		$values  = [];
		$lastKey = null;

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

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

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

		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;
	}

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

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	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 $bencoded)
47		{
48	61	if ($bencoded === '')
49		{
50	1	throw new InvalidArgumentException;
51		}
52
53	60	$this->bencoded = $bencoded;
54	60	$this->len = strlen($bencoded);
55	60	$this->pos = 0;
56
57	60	$this->computeSafeBoundary();
58		}
59
60	60	protected function checkBoundary(): void
61		{
62	60	if ($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	12	protected function complianceError(string $message): void
90		{
91	12	throw new RuntimeException($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	60	protected function computeSafeBoundary(): void
100		{
101	60	$boundary = $this->len - 1;
102	60	$c = $this->bencoded[$boundary];
103	60	while (is_numeric($c) && --$boundary >= 0)
104		{
105	7	$c = $this->bencoded[$boundary];
106		}
107	60	if ($c === '-')
108		{
109	6	$boundary -= 2;
110		}
111	54	elseif ($c === 'i')
112		{
113	6	--$boundary;
114		}
115
116	60	$this->max = $boundary;
117	60	$this->checkBoundary();
118		}
119
120	50	protected function decodeAnything()
121		{
122	50	$c = $this->bencoded[$this->pos];
123	50	if ($c === 'i')
124		{
125	17	return $this->decodeInteger();
126		}
127	41	if ($c === 'd')
128		{
129	15	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	15	protected function decodeDictionary(): ArrayObject
140		{
141	15	$values = [];
142	15	$lastKey = null;
143
144	15	++$this->pos;
145	15	while ($this->pos <= $this->max)
146		{
147	15	if ($this->bencoded[$this->pos] === 'e')
148		{
149	7	++$this->pos;
150
151	7	return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
152		}
153
154	14	$pos = $this->pos;
155	14	$key = $this->decodeString();
156	13	if ($key <= $lastKey)
157		{
158	4	$this->dictionaryError($pos, $key, $lastKey);
159		}
160	13	if ($this->pos > $this->max)
161		{
162	1	break;
163		}
164	12	$values[$key] = $this->decodeAnything();
165	9	$lastKey = $key;
166		}
167
168	1	throw new RuntimeException('Premature end of data');
169		}
170
171	43	protected function decodeDigits(string $terminator): int
172		{
173		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
174	43	$spn = strspn($this->bencoded, '4615302879', $this->pos);
175	43	if (!$spn)
176		{
177	7	throw new RuntimeException('Illegal character found at offset ' . $this->pos);
178		}
179	38	if ($this->bencoded[$this->pos] === '0' && $spn > 1)
180		{
181	3	$this->complianceError('Illegal character found at offset ' . (1 + $this->pos));
182		}
183
184		// Capture the value and cast it as an integer
185	35	$value = (int) substr($this->bencoded, $this->pos, $spn);
186
187	35	$this->pos += $spn;
188	35	if ($this->bencoded[$this->pos] !== $terminator)
189		{
190	5	throw new RuntimeException('Illegal character found at offset ' . $this->pos);
191		}
192	30	++$this->pos;
193
194	30	return $value;
195		}
196
197	17	protected function decodeInteger(): int
198		{
199	17	$negative = ($this->bencoded[++$this->pos] === '-');
200	17	if ($negative && $this->bencoded[++$this->pos] === '0')
201		{
202	1	$this->complianceError('Illegal character found at offset ' . $this->pos);
203		}
204
205	16	$value = $this->decodeDigits('e');
206
207	11	return ($negative) ? -$value : $value;
208		}
209
210	12	protected function decodeList(): array
211		{
212	12	++$this->pos;
213
214	12	$list = [];
215	12	while ($this->pos <= $this->max)
216		{
217	11	if ($this->bencoded[$this->pos] === 'e')
218		{
219	7	++$this->pos;
220
221	7	return $list;
222		}
223
224	8	$list[] = $this->decodeAnything();
225		}
226
227	4	throw new RuntimeException('Premature end of data');
228		}
229
230	34	protected function decodeString(): string
231		{
232	34	$len = $this->decodeDigits(':');
233	26	$string = substr($this->bencoded, $this->pos, $len);
234	26	$this->pos += $len;
235
236	26	return $string;
237		}
238
239	4	protected function dictionaryError(int $pos, string $key, ?string $lastKey)
240		{
241	4	if ($key === $lastKey)
242		{
243	2	$this->complianceError("Duplicate dictionary entry '" . $key . "' at pos " . $pos);
244		}
245	2	elseif ($key < $lastKey)
246		{
247	1	$this->complianceError("Out-of-order dictionary entry '" . $key . "' at pos " . $pos);
248		}
249		}
250		}

s9e / Bencode

Push — DictionaryOrder ( d89a7c )

Decoder::dictionaryError() A

Complexity

Size

Duplication

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