Optional::newEmpty() - Code Metrics - Inspection of "Merge pull request #43 from Ocramius/dependabot/co..." - Ocramius/ocramius.util.Optional - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( b367d7...03bf23 )

by Marco

created 2020-06-26 13:43 UTC

Optional::newEmpty() A

↳ Parent: Project

Complexity

Conditions	2
Paths	2

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	2
CRAP Score	2

Importance

Changes

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

<?php
/*
 * Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 */

declare(strict_types=1);

namespace ocramius\util;

use Exception;
use ocramius\util\exception\NoSuchElementException;
use ocramius\util\exception\NullPointerException;
use Throwable;

use function sprintf;
use function strval;

/**
 * A container object which may or may not contain a non-null value.
 * If a value is present, {@code isPresent()} will return {@code true} and
 * {@code get()} will return the value.
 *
 * <p>Additional methods that depend on the presence or absence of a contained
 * value are provided, such as {@link #orElse(java.lang.Object) orElse()}
 * (return a default value if value not present) and
 * {@link #ifPresent(java.util.function.Consumer) ifPresent()} (execute a block
 * of code if the value is present).
 *
 * <p>This is a value-based class; use of identity-sensitive operations
 * (including reference equality ({@code ==}), identity hash code, or
 * synchronization) on instances of {@code Optional} may have unpredictable
 * results and should be avoided.
 *
 * @template T The type of the value residing in the Optional wrapper.
 */
final class Optional
{
    /**
     * Common instance for {@code empty()}.
     */
    private static ?self $EMPTY = null;


    /**
     * If non-null, the value; if null, indicates no value is present
     *
     * @psalm-var T
     * @var mixed
     */
    private $value;

    /**
     * Constructs an empty instance.
     *
     * @implNote Generally only one empty instance, {@link Optional#EMPTY},
     * should exist per VM.
     * @psalm-return self<T>
     */
    private function __construct()
    {
    }

    /**
     * Returns an empty {@code Optional} instance.  No value is present for this
     * Optional.
     *
     * @return self an empty {@code Optional}
     *
     * @apiNote Though it may be tempting to do so, avoid testing if an object
     * is empty by comparing with {@code ==} against instances returned by
     * {@code Option.empty()}. There is no guarantee that it is a singleton.
     * Instead, use {@link #isPresent()}.
     */
    public static function newEmpty(): self
    {
        return self::$EMPTY ?: self::$EMPTY = new self();
    }

    /**
     * Returns an {@code Optional} with the specified present non-null value.
     *
     * @param mixed $value the value to be present, which must be non-null
     *
     * @return self an {@code Optional} with the value present
     *
     * @throws NullPointerException If value is null.
     *
     * @psalm-return self<T>
     * @psalm-template T
     * @psalm-param T $value
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public static function of($value): self
    {
        if ($value === null) {
            throw new NullPointerException();
        }

        $self = new self();

        $self->value = $value;

        return $self;
    }

    /**
     * Returns an {@code Optional} describing the specified value, if non-null,
     * otherwise returns an empty {@code Optional}.
     *
     * @param mixed|null $value the possibly-null value to describe
     *
     * @return self an {@code Optional} with a present value if the specified value
     * is non-null, otherwise an empty {@code Optional}
     *
     * @psalm-template T
     * @psalm-param T|null $value
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public static function ofNullable($value): self
    {
        return $value === null ? self::newEmpty() : self::of($value);
    }

    /**
     * If a value is present in this {@code Optional}, returns the value,
     * otherwise throws {@code NoSuchElementException}.
     *
     * @see Optional#isPresent()
     *
     * @return mixed the non-null value held by this {@code Optional}
     *
     * @throws NoSuchElementException If there is no value present.
     *
     * @psalm-return T
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public function get()
    {
        if ($this->value === null) {
            throw new NoSuchElementException('No value present');
        }

        return $this->value;
    }

    /**
     * Return {@code true} if there is a value present, otherwise {@code false}.
     *
     * @return bool {@code true} if there is a value present, otherwise {@code false}
     */
    public function isPresent(): bool
    {
        return $this->value !== null;
    }

    /**
     * If a value is present, invoke the specified consumer with the value,
     * otherwise do nothing.
     *
     * @param callable $consumer block to be executed if a value is present
     *
     * @psalm-param callable(T):void $consumer
     */
    public function ifPresent(callable $consumer): void
    {
        if ($this->value === null) {
            return;
        }

        $consumer($this->value);
    }

    /**
     * If a value is present, and the value matches the given predicate,
     * return an {@code Optional} describing the value, otherwise return an
     * empty {@code Optional}.
     *
     * @param callable $predicate a predicate to apply to the value, if present
     *
     * @return self an {@code Optional} describing the value of this {@code Optional}
     * if a value is present and the value matches the given predicate,
     * otherwise an empty {@code Optional}
     *
     * @throws NullPointerException If the predicate is null.
     *
     * @psalm-param callable(T):self $predicate
     */
    public function filter(callable $predicate): self
    {
        if ($this->value === null) {
            return $this;
        }

        return $predicate($this->value) ? $this : self::newEmpty();
    }

    /**
     * If a value is present, apply the provided mapping function to it,
     * and if the result is non-null, return an {@code Optional} describing the
     * result.  Otherwise return an empty {@code Optional}.
     *
     * @param callable $mapper a mapping function to apply to the value, if present
     *
     * @return self an {@code Optional} describing the result of applying a mapping
     * function to the value of this {@code Optional}, if a value is present,
     * otherwise an empty {@code Optional}
     *
     * @throws NullPointerException If the mapping function is null.
     *
     * @psalm-param callable(T):U $mapper
     * @psalm-return self<U>
     * @apiNote This method supports post-processing on optional values, without
     * the need to explicitly check for a return status.  For example, the
     * following code traverses a stream of file names, selects one that has
     * not yet been processed, and then opens that file, returning an
     * {@code Optional<FileInputStream>}:
     *
     * <pre>{@code
     *     Optional<FileInputStream> fis =
     *         names.stream().filter(name -> !isProcessedYet(name))
     *                       .findFirst()
     *                       .map(name -> new FileInputStream(name));
     * }</pre>
     *
     * Here, {@code findFirst} returns an {@code Optional<String>}, and then
     * {@code map} returns an {@code Optional<FileInputStream>} for the desired
     * file if one exists.
     * @template U
     */
    public function map(callable $mapper): self
    {
        if ($this->value === null) {
            return self::newEmpty();
        }

        return self::ofNullable($mapper($this->value));
    }

    /**
     * If a value is present, apply the provided {@code Optional}-bearing
     * mapping function to it, return that result, otherwise return an empty
     * {@code Optional}.  This method is similar to {@link #map(Function)},
     * but the provided mapper is one whose result is already an {@code Optional},
     * and if invoked, {@code flatMap} does not wrap it with an additional
     * {@code Optional}.
     *
     * @param callable $mapper a mapping function to apply to the value, if present
     *           the mapping function
     *
     * @return self the result of applying an {@code Optional}-bearing mapping
     * function to the value of this {@code Optional}, if a value is present,
     * otherwise an empty {@code Optional}
     *
     * @throws NullPointerException If the mapping function is null or returns
     * a null result.
     *
     * @template U
     * @psalm-param callable(T):self<U> $mapper
     * @psalm-return self<U>
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public function flatMap(callable $mapper): self
    {
        if ($this->value === null) {
            return self::newEmpty();
        }

        $result = $mapper($this->value);

        if ($result === null) {
            throw new NullPointerException();
        }

        return $result;
    }

    /**
     * Return the value if present, otherwise return {@code other}.
     *
     * @param mixed $other the value to be returned if there is no value present, may
     * be null
     *
     * @return mixed the value, if present, otherwise {@code other}
     *
     * @psalm-param T $other
     * @psalm-return T
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public function orElse($other)
    {
        return $this->value ?? $other;
    }

    /**
     * Return the value if present, otherwise invoke {@code other} and return
     * the result of that invocation.
     *
     * @param callable $other a {@code Supplier} whose result is returned if no value
     * is present
     *
     * @return mixed the value if present otherwise the result of {@code other.get()}
     *
     * @throws NullPointerException If value is not present and {@code other} is
     * null.
     *
     * @psalm-param callable():T $other
     * @psalm-return T
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public function orElseGet(callable $other)
    {
        return $this->value ?? $other();
    }

    /**
     * Return the contained value, if present, otherwise throw an exception
     * to be created by the provided supplier.
     *
     * @param callable $exceptionSupplier The supplier which will return the exception to
     * be thrown
     *
     * @return mixed the present value
     *
     * @throws Exception If there is no value present.
     * @throws NullPointerException If no value is present and
     * {@code exceptionSupplier} is null.
     *
     * @psalm-param callable(): Throwable $exceptionSupplier
     * @psalm-return T
     * @apiNote A method reference to the exception constructor with an empty
     * argument list can be used as the supplier. For example,
     * {@code IllegalStateException::new}
     * @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
     */
    public function orElseThrow(callable $exceptionSupplier)
    {
        if ($this->value === null) {
            throw $exceptionSupplier();
        }

        return $this->value;
    }

    /**
     * Indicates whether some other object is "equal to" this Optional. The
     * other object is considered equal if:
     * <ul>
     * <li>it is also an {@code Optional} and;
     * <li>both instances have no value present or;
     * <li>the present values are "equal to" each other via {@code equals()}.
     * </ul>
     *
     * @param mixed $object an object to be tested for equality
     *
     * @return bool {code true} if the other object is "equal to" this object
     * otherwise {@code false}
     */
    public function equals($object): bool
    {
        return $object === $this || ($object instanceof self && $object->value === $this->value);
    }

    /**
     * Returns a non-empty string representation of this Optional suitable for
     * debugging. The exact presentation format is unspecified and may vary
     * between implementations and versions.
     *
     * @return string the string representation of this instance
     *
     * @implSpec If a value is present the result must include its string
     * representation in the result. Empty and present Optionals must be
     * unambiguously differentiable.
     */
    public function __toString(): string
    {
        return $this->value === null ? 'Optional.empty' : sprintf('Optional[%s]', strval($this->value));
    }
}


1		<?php
2		/*
3		* Oracle designates this
4		* particular file as subject to the "Classpath" exception as provided
5		* by Oracle in the LICENSE file that accompanied this code.
6		*/
7
8		declare(strict_types=1);
9
10		namespace ocramius\util;
11
12		use Exception;
13		use ocramius\util\exception\NoSuchElementException;
14		use ocramius\util\exception\NullPointerException;
15		use Throwable;
16
17		use function sprintf;
18		use function strval;
19
20		/**
21		* A container object which may or may not contain a non-null value.
22		* If a value is present, {@code isPresent()} will return {@code true} and
23		* {@code get()} will return the value.
24		*
25		* <p>Additional methods that depend on the presence or absence of a contained
26		* value are provided, such as {@link #orElse(java.lang.Object) orElse()}
27		* (return a default value if value not present) and
28		* {@link #ifPresent(java.util.function.Consumer) ifPresent()} (execute a block
29		* of code if the value is present).
30		*
31		* <p>This is a value-based class; use of identity-sensitive operations
32		* (including reference equality ({@code ==}), identity hash code, or
33		* synchronization) on instances of {@code Optional} may have unpredictable
34		* results and should be avoided.
35		*
36		* @template T The type of the value residing in the Optional wrapper.
37		*/
38		final class Optional
39		{
40		/**
41		* Common instance for {@code empty()}.
42		*/
43		private static ?self $EMPTY = null;
		0 ignored issues – show Bug introduced 2020-06-14 18:58 UTC by Report Bug Copy Issue Report This code did not parse for me. Apparently, there is an error somewhere around this line: Syntax error, unexpected '?', expecting T_FUNCTION or T_CONST Loading history...
44
45		/**
46		* If non-null, the value; if null, indicates no value is present
47		*
48		* @psalm-var T
49		* @var mixed
50		*/
51		private $value;
52
53		/**
54		* Constructs an empty instance.
55		*
56		* @implNote Generally only one empty instance, {@link Optional#EMPTY},
57		* should exist per VM.
58		* @psalm-return self<T>
59		*/
60	101	private function __construct()
61		{
62	101	}
63
64		/**
65		* Returns an empty {@code Optional} instance. No value is present for this
66		* Optional.
67		*
68		* @return self an empty {@code Optional}
69		*
70		* @apiNote Though it may be tempting to do so, avoid testing if an object
71		* is empty by comparing with {@code ==} against instances returned by
72		* {@code Option.empty()}. There is no guarantee that it is a singleton.
73		* Instead, use {@link #isPresent()}.
74		*/
75	68	public static function newEmpty(): self
76		{
77	68	return self::$EMPTY ?: self::$EMPTY = new self();
78		}
79
80		/**
81		* Returns an {@code Optional} with the specified present non-null value.
82		*
83		* @param mixed $value the value to be present, which must be non-null
84		*
85		* @return self an {@code Optional} with the value present
86		*
87		* @throws NullPointerException If value is null.
88		*
89		* @psalm-return self<T>
90		* @psalm-template T
91		* @psalm-param T $value
92		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
93		*/
94	101	public static function of($value): self
95		{
96	101	if ($value === null) {
97	1	throw new NullPointerException();
98		}
99
100	100	$self = new self();
101
102	100	$self->value = $value;
103
104	100	return $self;
105		}
106
107		/**
108		* Returns an {@code Optional} describing the specified value, if non-null,
109		* otherwise returns an empty {@code Optional}.
110		*
111		* @param mixed\|null $value the possibly-null value to describe
112		*
113		* @return self an {@code Optional} with a present value if the specified value
114		* is non-null, otherwise an empty {@code Optional}
115		*
116		* @psalm-template T
117		* @psalm-param T\|null $value
118		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
119		*/
120	26	public static function ofNullable($value): self
121		{
122	26	return $value === null ? self::newEmpty() : self::of($value);
123		}
124
125		/**
126		* If a value is present in this {@code Optional}, returns the value,
127		* otherwise throws {@code NoSuchElementException}.
128		*
129		* @see Optional#isPresent()
130		*
131		* @return mixed the non-null value held by this {@code Optional}
132		*
133		* @throws NoSuchElementException If there is no value present.
134		*
135		* @psalm-return T
136		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
137		*/
138	25	public function get()
139		{
140	25	if ($this->value === null) {
141	1	throw new NoSuchElementException('No value present');
142		}
143
144	24	return $this->value;
145		}
146
147		/**
148		* Return {@code true} if there is a value present, otherwise {@code false}.
149		*
150		* @return bool {@code true} if there is a value present, otherwise {@code false}
151		*/
152	17	public function isPresent(): bool
153		{
154	17	return $this->value !== null;
155		}
156
157		/**
158		* If a value is present, invoke the specified consumer with the value,
159		* otherwise do nothing.
160		*
161		* @param callable $consumer block to be executed if a value is present
162		*
163		* @psalm-param callable(T):void $consumer
164		*/
165	9	public function ifPresent(callable $consumer): void
166		{
167	9	if ($this->value === null) {
168	1	return;
169		}
170
171	8	$consumer($this->value);
172	8	}
173
174		/**
175		* If a value is present, and the value matches the given predicate,
176		* return an {@code Optional} describing the value, otherwise return an
177		* empty {@code Optional}.
178		*
179		* @param callable $predicate a predicate to apply to the value, if present
180		*
181		* @return self an {@code Optional} describing the value of this {@code Optional}
182		* if a value is present and the value matches the given predicate,
183		* otherwise an empty {@code Optional}
184		*
185		* @throws NullPointerException If the predicate is null.
186		*
187		* @psalm-param callable(T):self $predicate
188		*/
189	17	public function filter(callable $predicate): self
190		{
191	17	if ($this->value === null) {
192	1	return $this;
193		}
194
195	16	return $predicate($this->value) ? $this : self::newEmpty();
196		}
197
198		/**
199		* If a value is present, apply the provided mapping function to it,
200		* and if the result is non-null, return an {@code Optional} describing the
201		* result. Otherwise return an empty {@code Optional}.
202		*
203		* @param callable $mapper a mapping function to apply to the value, if present
204		*
205		* @return self an {@code Optional} describing the result of applying a mapping
206		* function to the value of this {@code Optional}, if a value is present,
207		* otherwise an empty {@code Optional}
208		*
209		* @throws NullPointerException If the mapping function is null.
210		*
211		* @psalm-param callable(T):U $mapper
212		* @psalm-return self<U>
213		* @apiNote This method supports post-processing on optional values, without
214		* the need to explicitly check for a return status. For example, the
215		* following code traverses a stream of file names, selects one that has
216		* not yet been processed, and then opens that file, returning an
217		* {@code Optional<FileInputStream>}:
218		*
219		* <pre>{@code
220		* Optional<FileInputStream> fis =
221		* names.stream().filter(name -> !isProcessedYet(name))
222		* .findFirst()
223		* .map(name -> new FileInputStream(name));
224		* }</pre>
225		*
226		* Here, {@code findFirst} returns an {@code Optional<String>}, and then
227		* {@code map} returns an {@code Optional<FileInputStream>} for the desired
228		* file if one exists.
229		* @template U
230		*/
231	10	public function map(callable $mapper): self
232		{
233	10	if ($this->value === null) {
234	1	return self::newEmpty();
235		}
236
237	9	return self::ofNullable($mapper($this->value));
238		}
239
240		/**
241		* If a value is present, apply the provided {@code Optional}-bearing
242		* mapping function to it, return that result, otherwise return an empty
243		* {@code Optional}. This method is similar to {@link #map(Function)},
244		* but the provided mapper is one whose result is already an {@code Optional},
245		* and if invoked, {@code flatMap} does not wrap it with an additional
246		* {@code Optional}.
247		*
248		* @param callable $mapper a mapping function to apply to the value, if present
249		* the mapping function
250		*
251		* @return self the result of applying an {@code Optional}-bearing mapping
252		* function to the value of this {@code Optional}, if a value is present,
253		* otherwise an empty {@code Optional}
254		*
255		* @throws NullPointerException If the mapping function is null or returns
256		* a null result.
257		*
258		* @template U
259		* @psalm-param callable(T):self<U> $mapper
260		* @psalm-return self<U>
261		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
262		*/
263	10	public function flatMap(callable $mapper): self
264		{
265	10	if ($this->value === null) {
266	1	return self::newEmpty();
267		}
268
269	9	$result = $mapper($this->value);
270
271	9	if ($result === null) {
272	1	throw new NullPointerException();
273		}
274
275	8	return $result;
276		}
277
278		/**
279		* Return the value if present, otherwise return {@code other}.
280		*
281		* @param mixed $other the value to be returned if there is no value present, may
282		* be null
283		*
284		* @return mixed the value, if present, otherwise {@code other}
285		*
286		* @psalm-param T $other
287		* @psalm-return T
288		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
289		*/
290	16	public function orElse($other)
291		{
292	16	return $this->value ?? $other;
293		}
294
295		/**
296		* Return the value if present, otherwise invoke {@code other} and return
297		* the result of that invocation.
298		*
299		* @param callable $other a {@code Supplier} whose result is returned if no value
300		* is present
301		*
302		* @return mixed the value if present otherwise the result of {@code other.get()}
303		*
304		* @throws NullPointerException If value is not present and {@code other} is
305		* null.
306		*
307		* @psalm-param callable():T $other
308		* @psalm-return T
309		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
310		*/
311	16	public function orElseGet(callable $other)
312		{
313	16	return $this->value ?? $other();
314		}
315
316		/**
317		* Return the contained value, if present, otherwise throw an exception
318		* to be created by the provided supplier.
319		*
320		* @param callable $exceptionSupplier The supplier which will return the exception to
321		* be thrown
322		*
323		* @return mixed the present value
324		*
325		* @throws Exception If there is no value present.
326		* @throws NullPointerException If no value is present and
327		* {@code exceptionSupplier} is null.
328		*
329		* @psalm-param callable(): Throwable $exceptionSupplier
330		* @psalm-return T
331		* @apiNote A method reference to the exception constructor with an empty
332		* argument list can be used as the supplier. For example,
333		* {@code IllegalStateException::new}
334		* @phpcsSuppress SlevomatCodingStandard.TypeHints.TypeHintDeclaration
335		*/
336	9	public function orElseThrow(callable $exceptionSupplier)
337		{
338	9	if ($this->value === null) {
339	1	throw $exceptionSupplier();
340		}
341
342	8	return $this->value;
343		}
344
345		/**
346		* Indicates whether some other object is "equal to" this Optional. The
347		* other object is considered equal if:
348		* <ul>
349		* <li>it is also an {@code Optional} and;
350		* <li>both instances have no value present or;
351		* <li>the present values are "equal to" each other via {@code equals()}.
352		* </ul>
353		*
354		* @param mixed $object an object to be tested for equality
355		*
356		* @return bool {code true} if the other object is "equal to" this object
357		* otherwise {@code false}
358		*/
359	17	public function equals($object): bool
360		{
361	17	return $object === $this \|\| ($object instanceof self && $object->value === $this->value);
362		}
363
364		/**
365		* Returns a non-empty string representation of this Optional suitable for
366		* debugging. The exact presentation format is unspecified and may vary
367		* between implementations and versions.
368		*
369		* @return string the string representation of this instance
370		*
371		* @implSpec If a value is present the result must include its string
372		* representation in the result. Empty and present Optionals must be
373		* unambiguously differentiable.
374		*/
375	1	public function __toString(): string
376		{
377	1	return $this->value === null ? 'Optional.empty' : sprintf('Optional[%s]', strval($this->value));
378		}
379		}
380

Ocramius / ocramius.util.Optional

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Optional::newEmpty() A

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