BitString::bitAnd() - Code Metrics - Inspection of "update Travis configuration to also test on PHP 7...." - ondrej-bouda/ivory - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( c327c2...0adcf0 )

by Ondřej

created 2018-02-03 23:45 UTC

BitString::bitAnd() B

↳ Parent: BitString

Complexity

Conditions	5
Paths	4

Size

Total Lines	14
Code Lines	7

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	5
eloc	7
nc	4
nop	1
dl	0
loc	14
rs	8.8571
c	0
b	0
f	0

<?php
declare(strict_types=1);
namespace Ivory\Value;

use Ivory\Exception\ImmutableException;
use Ivory\Exception\IncomparableException;
use Ivory\Exception\UndefinedOperationException;
use Ivory\Value\Alg\IComparable;

/**
 * A common super type for bit string types - strings of 1's and 0's.
 *
 * The objects are immutable, i.e., operations always produce a new object.
 * The representation and operations resemble the specification for bit string types in PostgreSQL.
 *
 * It is possible to access individual bits using the array indices (readonly). The leftmost bit is at offset 0. Testing
 * whether the bit string has a bit at a given offset may be performed using `isset($this[$offset])`. Note that, apart
 * from reading out of such a call, it does not test whether the given bit is *set* (i.e., whether it is 1) - it merely
 * tests whether it is legal to access it. Negative offsets may be used to get bits off the end of the string.
 *
 * @see http://www.postgresql.org/docs/current/static/datatype-bit.html PostgreSQL Bit String Types
 * @see http://www.postgresql.org/docs/current/static/functions-bitstring.html PostgreSQL Bit String Functions and Operators
 *
 * @todo optimize the internal representation (unpack('c*', $value) might be handy for constructing from string)
 */
abstract class BitString implements IComparable, \ArrayAccess
{
    protected $bits;
    protected $len;


    /**
     * @param string $bits
     */
    protected function __construct(string $bits)
    {
        if (!preg_match('~^[01]*$~', $bits)) {
            throw new \InvalidArgumentException('bits');
        }

        $this->bits = $bits;
        $this->len = strlen($bits);
    }


    /**
     * @return string textual representation of this bit string (index 0 is the leftmost bit): a string of 1's and 0's
     */
    public function toString(): string
    {
        return $this->bits;
    }

    /**
     * @return int number of bits in the bit string
     */
    public function getLength(): int
    {
        return $this->len;
    }

    /**
     * @return bool whether all the bits are zero
     */
    public function isZero(): bool
    {
        return !$this->isNonZero();
    }

    /**
     * @return bool whether some bit is one
     */
    public function isNonZero(): bool
    {
        for ($i = 0; $i < $this->len; $i++) {
            if ($this->bits[$i] == '1') {
                return true;
            }
        }

        return false;
    }

    /**
     * @param BitString|null $other
     * @return bool whether this and the other bit string are of the same type, have the same bits and same length
     */
    public function equals($other): bool
    {
        return (
            $other !== null &&
            get_class($this) == get_class($other) &&
            $this->bits == $other->bits
        );
    }

    public function compareTo($other): int
    {
        if ($other === null) {
            throw new \InvalidArgumentException('comparing with null');
        }
        if (get_class($this) != get_class($other)) {
            throw new IncomparableException();
        }

        return strcmp($this->bits, $other->bits);
    }

    /**
     * @param BitString $other any bit string of any length
     * @return bool whether this and the other bit string have the same bits, i.e., are the same 1's and 0's strings
     */
    public function bitEquals(BitString $other): bool
    {
        return ($this->bits === $other->bits); // ===: PHP would otherwise convert both strings to integers
    }

    /**
     * Finds out whether the operands intersect at a 1 bit.
     *
     * Works for any lengths of the bit strings. The shorter bit string is right-padded with 0's.
     *
     * @param BitString $other any bit string of any length
     * @return bool whether this and the other bit string share at least one set bit at the same offset
     */
    public function intersects(BitString $other): bool
    {
        for ($i = min($this->len, $other->len) - 1; $i >= 0; $i--) {
            if ($this->bits[$i] == '1' && $other->bits[$i] == '1') {
                return true;
            }
        }

        return false;
    }

    /**
     * Extracts a bit substring from this bit string.
     *
     * Note the semantics are according to the SQL standard, which PostgreSQL implements. That is, the arguments do NOT
     * work the same as for PHP {@link substr()} function.
     *
     * Examples:
     * - `substring(2)` on `'1101001'` yields `'101001'`
     * - `substring(2, 4)` on `'1101001'` yields `'1010'`
     * - `substring(2, 0)` on `'1101001'` yields `''`
     * - `substring(-2, 4)` on `'1101001'` yields `'1'`
     *
     * @param int $from position to start at;
     *                  one-based - e.g., <tt>$from = 2</tt> omits the first character;
     *                  if less than one, it yields the start of the string, but counting from the given (negative or
     *                    zero) position, effectively decreasing the <tt>$for</tt> argument, if given
     * @param int|null $for number of characters to take; must be non-negative;
     *                      <tt>null</tt> for the rest of the string
     * @return FixedBitString the substring of the bit string
     * @throws UndefinedOperationException when <tt>$for</tt> is negative
     */
    public function substring(int $from, ?int $for = null): FixedBitString
    {
        if ($for < 0) {
            throw new UndefinedOperationException('negative number of bits to take');
        }

        $offset = max(0, $from - 1);
        if ($offset >= $this->len) {
            return FixedBitString::fromString('');
        }

        if ($for === null) {
            $len = $this->len;
        } elseif ($from >= 0) {
            $len = $for;
        } else {
            $len = max(0, $for + $from - 1);
        }

        return FixedBitString::fromString(substr($this->bits, $offset, $len));
    }

    /**
     * Concatenates this bit string with another one.
     *
     * The result is a bit string with bits of this bit string followed by the bits from the `$concatenated` bit string.
     *
     * If both the operands are fixed-length of length `A` and `B`, the result is a fixed-length bit string of length
     * `A+B`. Otherwise, the result is a variable-length bit string.
     *
     * @param BitString $concatenated
     * @return VarBitString bit string made up by concatenating the <tt>$concatenated</tt> after this bit string
     */
    public function concat(BitString $concatenated): VarBitString
    {
        return VarBitString::fromString($this->bits . $concatenated->bits);
    }

    /**
     * Bitwise AND operation. Only legal for operands of equal bit lengths.
     *
     * @param BitString $other the other operand
     * @return FixedBitString new bit string: <tt>$this & $other</tt>
     * @throws UndefinedOperationException if the operands are of different bit lengths
     */
    public function bitAnd(BitString $other): FixedBitString
    {
        if ($this->len != $other->len) {
            throw new UndefinedOperationException('operands are of different bit lengths');
        }

        $res = str_repeat('0', $this->len);
        for ($i = 0; $i < $this->len; $i++) {
            if ($this->bits[$i] == '1' && $other->bits[$i] == '1') {
                $res[$i] = '1';
            }
        }

        return FixedBitString::fromString($res);
    }

    /**
     * Bitwise OR operation. Only legal for operands of equal bit lengths.
     *
     * @param BitString $other the other operand
     * @return FixedBitString new bit string: <tt>$this | $other</tt>
     * @throws UndefinedOperationException if the operands are of different bit lengths
     */
    public function bitOr(BitString $other): FixedBitString
    {
        if ($this->len != $other->len) {
            throw new UndefinedOperationException('operands are of different bit lengths');
        }

        $res = str_repeat('1', $this->len);
        for ($i = 0; $i < $this->len; $i++) {
            if ($this->bits[$i] == '0' && $other->bits[$i] == '0') {
                $res[$i] = '0';
            }
        }

        return FixedBitString::fromString($res);
    }

    /**
     * Bitwise exclusive OR operation. Only legal for operands of equal bit lengths.
     *
     * @param BitString $other the other operand
     * @return FixedBitString new bit string: <tt>$this ^ $other</tt>
     * @throws UndefinedOperationException if the operands are of different bit lengths
     */
    public function bitXor(BitString $other): FixedBitString
    {
        if ($this->len != $other->len) {
            throw new UndefinedOperationException('operands are of different bit lengths');
        }

        $res = str_repeat('0', $this->len);
        for ($i = 0; $i < $this->len; $i++) {
            if ($this->bits[$i] != $other->bits[$i]) {
                $res[$i] = '1';
            }
        }

        return FixedBitString::fromString($res);
    }

    /**
     * Bitwise negation, i.e., reverses all bits of the bit string.
     *
     * @return FixedBitString new bit string: <tt>~$this</tt>
     */
    public function bitNot(): FixedBitString
    {
        return FixedBitString::fromString(strtr($this->bits, '01', '10'));
    }

    /**
     * Shifts the bits to the left.
     *
     * The length of the bit string is preserved, thus, the `$shift` left trailing bits are discarded. The shifted bit
     * positions are filled with 0's.
     *
     * @param int $shift number of positions to shift the bits to the left;
     *                   might even be negative (results in shifting to the right by <tt>-$shift</tt>)
     * @return FixedBitString a bit string with bits shifted by <tt>$shift</tt> to the left
     */
    public function bitShiftLeft(int $shift): FixedBitString
    {
        if ($shift < 0) {
            return $this->bitShiftRight(-$shift);
        }

        $pad = min($this->len, $shift);
        $prefix = ($pad == $this->len ? '' : substr($this->bits, $pad));
        return FixedBitString::fromString($prefix . str_repeat('0', $pad));
    }

    /**
     * Shifts the bits to the right.
     *
     * The length of the bit string is preserved, thus, the `$shift` right trailing bits are discarded. The shifted bit
     * positions are filled with 0's.
     *
     * @param int $shift number of positions to shift the bits to the right;
     *                   might even be negative (results in shifting to the left by <tt>-$shift</tt>)
     * @return FixedBitString a bit string with bits shifted by <tt>$shift</tt> to the right
     */
    public function bitShiftRight(int $shift): FixedBitString
    {
        if ($shift < 0) {
            return $this->bitShiftLeft(-$shift);
        }

        $pad = min($this->len, $shift);
        $postfix = substr($this->bits, 0, $this->len - $pad);
        return FixedBitString::fromString(str_repeat('0', $pad) . $postfix);
    }

    /**
     * Rotates the bits to the left.
     *
     * @param int $rot the length of the rotation
     * @return FixedBitString a bit string with <tt>$rot</tt> (mod length) leftmost bits moved to the back of the bit
     *                          string
     */
    public function bitRotateLeft(int $rot): FixedBitString
    {
        if ($rot < 0) {
            return $this->bitRotateRight(-$rot);
        }
        if ($this->len == 0) {
            return FixedBitString::fromString('');
        }

        $pos = $rot % $this->len;
        return FixedBitString::fromString(substr($this->bits, $pos) . substr($this->bits, 0, $pos));
    }

    /**
     * Rotates the bits to the right.
     *
     * @param int $rot the length of the rotation
     * @return FixedBitString a bit string with <tt>$rot</tt> (mod length) rightmost bits moved to the front of the bit
     *                          string
     */
    public function bitRotateRight(int $rot): FixedBitString
    {
        if ($rot < 0) {
            return $this->bitRotateLeft(-$rot);
        }
        if ($this->len == 0) {
            return FixedBitString::fromString('');
        }

        $pos = $this->len - ($rot % $this->len);
        return FixedBitString::fromString(substr($this->bits, $pos) . substr($this->bits, 0, $pos));
    }


    public function __toString()
    {
        return $this->toString();
    }


    /**
     * @param int $offset the bit to know existence of; 0 for the leftmost bit, 1 for the next bit, -1 for the rightmost
     *                      bit, etc.
     * @return bool <tt>true</tt> if the bit string has <tt>$offset</tt>-th bit defined,
     *              <tt>false</tt> if the bit string is too short (i.e., shorter than <tt>$offset+1</tt> bits)
     */
    public function offsetExists($offset)
    {
        if ($offset < 0 && PHP_VERSION_ID < 70100) { // PHP < 7.1 did not support negative string offsets
            $offset = $this->len + $offset;
        }

        return isset($this->bits[$offset]);
    }

    /**
     * @param int $offset the bit to get; 0 for the leftmost bit, 1 for the next bit, -1 for the rightmost bit, etc.
     * @return int|null 0 or 1 depending on whether the <tt>$offset</tt>-th bit is set, or
     *                  <tt>null</tt> if outside of the bit string
     */
    public function offsetGet($offset)
    {
        if ($offset < 0 && PHP_VERSION_ID < 70100) { // PHP < 7.1 did not support negative string offsets
            $offset = $this->len + $offset;
        }

        if (isset($this->bits[$offset])) {
            return (int)$this->bits[$offset];
        } else {
            return null;
        }
    }

    /**
     * Setting a bit is not implemented - the bit string is immutable.
     *
     * @param mixed $offset
     * @param mixed $value
     * @throws ImmutableException
     */
    public function offsetSet($offset, $value)
    {
        throw new ImmutableException();
    }

    /**
     * Unsetting a bit is not implemented - the bit string is immutable.
     *
     * @param mixed $offset
     * @throws ImmutableException
     */
    public function offsetUnset($offset)
    {
        throw new ImmutableException();
    }
}


1			<?php
2			declare(strict_types=1);
3			namespace Ivory\Value;
4
5			use Ivory\Exception\ImmutableException;
6			use Ivory\Exception\IncomparableException;
7			use Ivory\Exception\UndefinedOperationException;
8			use Ivory\Value\Alg\IComparable;
9
10			/**
11			* A common super type for bit string types - strings of 1's and 0's.
12			*
13			* The objects are immutable, i.e., operations always produce a new object.
14			* The representation and operations resemble the specification for bit string types in PostgreSQL.
15			*
16			* It is possible to access individual bits using the array indices (readonly). The leftmost bit is at offset 0. Testing
17			* whether the bit string has a bit at a given offset may be performed using `isset($this[$offset])`. Note that, apart
18			* from reading out of such a call, it does not test whether the given bit is set (i.e., whether it is 1) - it merely
19			* tests whether it is legal to access it. Negative offsets may be used to get bits off the end of the string.
20			*
21			* @see http://www.postgresql.org/docs/current/static/datatype-bit.html PostgreSQL Bit String Types
22			* @see http://www.postgresql.org/docs/current/static/functions-bitstring.html PostgreSQL Bit String Functions and Operators
23			*
24			* @todo optimize the internal representation (unpack('c*', $value) might be handy for constructing from string)
25			*/
26			abstract class BitString implements IComparable, \ArrayAccess
27			{
28			protected $bits;
29			protected $len;
30
31
32			/**
33			* @param string $bits
34			*/
35			protected function __construct(string $bits)
36			{
37			if (!preg_match('~^[01]*$~', $bits)) {
38			throw new \InvalidArgumentException('bits');
39			}
40
41			$this->bits = $bits;
42			$this->len = strlen($bits);
43			}
44
45
46			/**
47			* @return string textual representation of this bit string (index 0 is the leftmost bit): a string of 1's and 0's
48			*/
49			public function toString(): string
50			{
51			return $this->bits;
52			}
53
54			/**
55			* @return int number of bits in the bit string
56			*/
57			public function getLength(): int
58			{
59			return $this->len;
60			}
61
62			/**
63			* @return bool whether all the bits are zero
64			*/
65			public function isZero(): bool
66			{
67			return !$this->isNonZero();
68			}
69
70			/**
71			* @return bool whether some bit is one
72			*/
73			public function isNonZero(): bool
74			{
75			for ($i = 0; $i < $this->len; $i++) {
76			if ($this->bits[$i] == '1') {
77			return true;
78			}
79			}
80
81			return false;
82			}
83
84			/**
85			* @param BitString\|null $other
86			* @return bool whether this and the other bit string are of the same type, have the same bits and same length
87			*/
88			public function equals($other): bool
89			{
90			return (
91			$other !== null &&
92			get_class($this) == get_class($other) &&
93			$this->bits == $other->bits
94			);
95			}
96
97			public function compareTo($other): int
98			{
99			if ($other === null) {
100			throw new \InvalidArgumentException('comparing with null');
101			}
102			if (get_class($this) != get_class($other)) {
103			throw new IncomparableException();
104			}
105
106			return strcmp($this->bits, $other->bits);
107			}
108
109			/**
110			* @param BitString $other any bit string of any length
111			* @return bool whether this and the other bit string have the same bits, i.e., are the same 1's and 0's strings
112			*/
113			public function bitEquals(BitString $other): bool
114			{
115			return ($this->bits === $other->bits); // ===: PHP would otherwise convert both strings to integers
116			}
117
118			/**
119			* Finds out whether the operands intersect at a 1 bit.
120			*
121			* Works for any lengths of the bit strings. The shorter bit string is right-padded with 0's.
122			*
123			* @param BitString $other any bit string of any length
124			* @return bool whether this and the other bit string share at least one set bit at the same offset
125			*/
126			public function intersects(BitString $other): bool
127			{
128			for ($i = min($this->len, $other->len) - 1; $i >= 0; $i--) {
129			if ($this->bits[$i] == '1' && $other->bits[$i] == '1') {
130			return true;
131			}
132			}
133
134			return false;
135			}
136
137			/**
138			* Extracts a bit substring from this bit string.
139			*
140			* Note the semantics are according to the SQL standard, which PostgreSQL implements. That is, the arguments do NOT
141			* work the same as for PHP {@link substr()} function.
142			*
143			* Examples:
144			* - `substring(2)` on `'1101001'` yields `'101001'`
145			* - `substring(2, 4)` on `'1101001'` yields `'1010'`
146			* - `substring(2, 0)` on `'1101001'` yields `''`
147			* - `substring(-2, 4)` on `'1101001'` yields `'1'`
148			*
149			* @param int $from position to start at;
150			* one-based - e.g., <tt>$from = 2</tt> omits the first character;
151			* if less than one, it yields the start of the string, but counting from the given (negative or
152			* zero) position, effectively decreasing the <tt>$for</tt> argument, if given
153			* @param int\|null $for number of characters to take; must be non-negative;
154			* <tt>null</tt> for the rest of the string
155			* @return FixedBitString the substring of the bit string
156			* @throws UndefinedOperationException when <tt>$for</tt> is negative
157			*/
158			public function substring(int $from, ?int $for = null): FixedBitString
159			{
160			if ($for < 0) {
161			throw new UndefinedOperationException('negative number of bits to take');
162			}
163
164			$offset = max(0, $from - 1);
165			if ($offset >= $this->len) {
166			return FixedBitString::fromString('');
167			}
168
169			if ($for === null) {
170			$len = $this->len;
171			} elseif ($from >= 0) {
172			$len = $for;
173			} else {
174			$len = max(0, $for + $from - 1);
175			}
176
177			return FixedBitString::fromString(substr($this->bits, $offset, $len));
178			}
179
180			/**
181			* Concatenates this bit string with another one.
182			*
183			* The result is a bit string with bits of this bit string followed by the bits from the `$concatenated` bit string.
184			*
185			* If both the operands are fixed-length of length `A` and `B`, the result is a fixed-length bit string of length
186			* `A+B`. Otherwise, the result is a variable-length bit string.
187			*
188			* @param BitString $concatenated
189			* @return VarBitString bit string made up by concatenating the <tt>$concatenated</tt> after this bit string
190			*/
191			public function concat(BitString $concatenated): VarBitString
192			{
193			return VarBitString::fromString($this->bits . $concatenated->bits);
194			}
195
196			/**
197			* Bitwise AND operation. Only legal for operands of equal bit lengths.
198			*
199			* @param BitString $other the other operand
200			* @return FixedBitString new bit string: <tt>$this & $other</tt>
201			* @throws UndefinedOperationException if the operands are of different bit lengths
202			*/
203			public function bitAnd(BitString $other): FixedBitString
204			{
205			if ($this->len != $other->len) {
206			throw new UndefinedOperationException('operands are of different bit lengths');
207			}
208
209			$res = str_repeat('0', $this->len);
210			for ($i = 0; $i < $this->len; $i++) {
211			if ($this->bits[$i] == '1' && $other->bits[$i] == '1') {
212			$res[$i] = '1';
213			}
214			}
215
216			return FixedBitString::fromString($res);
217			}
218
219			/**
220			* Bitwise OR operation. Only legal for operands of equal bit lengths.
221			*
222			* @param BitString $other the other operand
223			* @return FixedBitString new bit string: <tt>$this \| $other</tt>
224			* @throws UndefinedOperationException if the operands are of different bit lengths
225			*/
226			public function bitOr(BitString $other): FixedBitString
227			{
228			if ($this->len != $other->len) {
229			throw new UndefinedOperationException('operands are of different bit lengths');
230			}
231
232			$res = str_repeat('1', $this->len);
233			for ($i = 0; $i < $this->len; $i++) {
234			if ($this->bits[$i] == '0' && $other->bits[$i] == '0') {
235			$res[$i] = '0';
236			}
237			}
238
239			return FixedBitString::fromString($res);
240			}
241
242			/**
243			* Bitwise exclusive OR operation. Only legal for operands of equal bit lengths.
244			*
245			* @param BitString $other the other operand
246			* @return FixedBitString new bit string: <tt>$this ^ $other</tt>
247			* @throws UndefinedOperationException if the operands are of different bit lengths
248			*/
249			public function bitXor(BitString $other): FixedBitString
250			{
251			if ($this->len != $other->len) {
252			throw new UndefinedOperationException('operands are of different bit lengths');
253			}
254
255			$res = str_repeat('0', $this->len);
256			for ($i = 0; $i < $this->len; $i++) {
257			if ($this->bits[$i] != $other->bits[$i]) {
258			$res[$i] = '1';
259			}
260			}
261
262			return FixedBitString::fromString($res);
263			}
264
265			/**
266			* Bitwise negation, i.e., reverses all bits of the bit string.
267			*
268			* @return FixedBitString new bit string: <tt>~$this</tt>
269			*/
270			public function bitNot(): FixedBitString
271			{
272			return FixedBitString::fromString(strtr($this->bits, '01', '10'));
273			}
274
275			/**
276			* Shifts the bits to the left.
277			*
278			* The length of the bit string is preserved, thus, the `$shift` left trailing bits are discarded. The shifted bit
279			* positions are filled with 0's.
280			*
281			* @param int $shift number of positions to shift the bits to the left;
282			* might even be negative (results in shifting to the right by <tt>-$shift</tt>)
283			* @return FixedBitString a bit string with bits shifted by <tt>$shift</tt> to the left
284			*/
285			public function bitShiftLeft(int $shift): FixedBitString
286			{
287			if ($shift < 0) {
288			return $this->bitShiftRight(-$shift);
289			}
290
291			$pad = min($this->len, $shift);
292			$prefix = ($pad == $this->len ? '' : substr($this->bits, $pad));
293			return FixedBitString::fromString($prefix . str_repeat('0', $pad));
294			}
295
296			/**
297			* Shifts the bits to the right.
298			*
299			* The length of the bit string is preserved, thus, the `$shift` right trailing bits are discarded. The shifted bit
300			* positions are filled with 0's.
301			*
302			* @param int $shift number of positions to shift the bits to the right;
303			* might even be negative (results in shifting to the left by <tt>-$shift</tt>)
304			* @return FixedBitString a bit string with bits shifted by <tt>$shift</tt> to the right
305			*/
306			public function bitShiftRight(int $shift): FixedBitString
307			{
308			if ($shift < 0) {
309			return $this->bitShiftLeft(-$shift);
310			}
311
312			$pad = min($this->len, $shift);
313			$postfix = substr($this->bits, 0, $this->len - $pad);
314			return FixedBitString::fromString(str_repeat('0', $pad) . $postfix);
315			}
316
317			/**
318			* Rotates the bits to the left.
319			*
320			* @param int $rot the length of the rotation
321			* @return FixedBitString a bit string with <tt>$rot</tt> (mod length) leftmost bits moved to the back of the bit
322			* string
323			*/
324			public function bitRotateLeft(int $rot): FixedBitString
325			{
326			if ($rot < 0) {
327			return $this->bitRotateRight(-$rot);
328			}
329			if ($this->len == 0) {
330			return FixedBitString::fromString('');
331			}
332
333			$pos = $rot % $this->len;
334			return FixedBitString::fromString(substr($this->bits, $pos) . substr($this->bits, 0, $pos));
335			}
336
337			/**
338			* Rotates the bits to the right.
339			*
340			* @param int $rot the length of the rotation
341			* @return FixedBitString a bit string with <tt>$rot</tt> (mod length) rightmost bits moved to the front of the bit
342			* string
343			*/
344			public function bitRotateRight(int $rot): FixedBitString
345			{
346			if ($rot < 0) {
347			return $this->bitRotateLeft(-$rot);
348			}
349			if ($this->len == 0) {
350			return FixedBitString::fromString('');
351			}
352
353			$pos = $this->len - ($rot % $this->len);
354			return FixedBitString::fromString(substr($this->bits, $pos) . substr($this->bits, 0, $pos));
355			}
356
357
358			public function __toString()
359			{
360			return $this->toString();
361			}
362
363
364			/**
365			* @param int $offset the bit to know existence of; 0 for the leftmost bit, 1 for the next bit, -1 for the rightmost
366			* bit, etc.
367			* @return bool <tt>true</tt> if the bit string has <tt>$offset</tt>-th bit defined,
368			* <tt>false</tt> if the bit string is too short (i.e., shorter than <tt>$offset+1</tt> bits)
369			*/
370			public function offsetExists($offset)
371			{
372			if ($offset < 0 && PHP_VERSION_ID < 70100) { // PHP < 7.1 did not support negative string offsets
373			$offset = $this->len + $offset;
374			}
375
376			return isset($this->bits[$offset]);
377			}
378
379			/**
380			* @param int $offset the bit to get; 0 for the leftmost bit, 1 for the next bit, -1 for the rightmost bit, etc.
381			* @return int\|null 0 or 1 depending on whether the <tt>$offset</tt>-th bit is set, or
382			* <tt>null</tt> if outside of the bit string
383			*/
384			public function offsetGet($offset)
385			{
386			if ($offset < 0 && PHP_VERSION_ID < 70100) { // PHP < 7.1 did not support negative string offsets
387			$offset = $this->len + $offset;
388			}
389
390			if (isset($this->bits[$offset])) {
391			return (int)$this->bits[$offset];
392			} else {
393			return null;
394			}
395			}
396
397			/**
398			* Setting a bit is not implemented - the bit string is immutable.
399			*
400			* @param mixed $offset
401			* @param mixed $value
402			* @throws ImmutableException
403			*/
404			public function offsetSet($offset, $value)
405			{
406			throw new ImmutableException();
407			}
408
409			/**
410			* Unsetting a bit is not implemented - the bit string is immutable.
411			*
412			* @param mixed $offset
413			* @throws ImmutableException
414			*/
415			public function offsetUnset($offset)
416			{
417			throw new ImmutableException();
418			}
419			}
420

ondrej-bouda / ivory

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BitString::bitAnd() B

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