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

Completed

Push — 2.0/master ( 68076f...9cf05b )

by Josh

created 2020-08-29 13:45 UTC

Decoder::checkCursorPosition() A

↳ Parent: Decoder

Complexity

Conditions	3
Paths	3

Size

Total Lines	10
Code Lines	4

Duplication

Lines	0
Ratio	0 %

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
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;

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

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

		$this->computeSafeBoundary();
	}

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

		$decoder->checkCursorPosition();

		return $value;
	}

	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');
		}
	}

	protected function checkCursorPosition(): void
	{
		if ($this->pos !== $this->len)
		{
			if ($this->pos > $this->len)
			{
				throw new RuntimeException('Premature end of data');
			}

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

	/**
	* Adjust the rightmost boundary to the last safe character
	*
	* 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->nonFatalError("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 ' . $this->pos);
		}
		elseif ($spn > 1 && $this->bencoded[$this->pos] === '0')
		{
			$this->nonFatalError('Illegal character found at offset ' . $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->nonFatalError('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 nonFatalError(string $message): void
	{
		throw new RuntimeException($message);
	}
}

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

s9e / Bencode

Push — 2.0/master ( 68076f...9cf05b )

Decoder::checkCursorPosition() A

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