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Completed
Push — master ( 23c92d...0cfe1b )
by Alexander
01:42
created

EnumerablePagination::take()   A

Complexity

Conditions 4
Paths 2

Size

Total Lines 13
Code Lines 8

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 4
eloc 8
c 0
b 0
f 0
nc 2
nop 1
dl 0
loc 13
rs 9.2
1
<?php
2
3
namespace YaLinqo;
4
5
use YaLinqo;
6
7
trait EnumerablePagination
8
{
9
    /**
10
     * Returns the value at a specified key in a sequence.
11
     * <p><b>Syntax</b>: elementAt (key)
12
     * <p>Returns the value at a specified key in a sequence.
13
     * <p>If the type of source iterator implements {@link ArrayAccess}, that implementation is used to obtain the value at the specified key. Otherwise, this method obtains the specified value.
14
     * <p>This method throws an exception if key is not found. To instead return a default value when the specified key is not found, use the {@link elementAtOrDefault} method.
15
     * @param mixed $key The key of the value to retrieve.
16
     * @throws \UnexpectedValueException If sequence does not contain value with specified key.
17
     * @return mixed The value at the key in the source sequence.
18
     * @package YaLinqo\Pagination
19
     */
20
    public function elementAt ($key)
21
    {
22
        /** @var $it \Iterator|\ArrayAccess */
23
        $it = $this->getIterator();
24
25
        if ($it instanceof \ArrayAccess) {
26
            if (!$it->offsetExists($key))
27
                throw new \UnexpectedValueException(Errors::NO_KEY);
28
            return $it->offsetGet($key);
29
        }
30
31
        foreach ($it as $k => $v) {
32
            if ($k === $key)
33
                return $v;
34
        }
35
        throw new \UnexpectedValueException(Errors::NO_KEY);
36
    }
37
38
    /**
39
     * Returns the value at a specified key in a sequence or a default value if the key is not found.
40
     * <p><b>Syntax</b>: elementAtOrDefault (key [, default])
41
     * <p>If the type of source iterator implements {@link ArrayAccess}, that implementation is used to obtain the value at the specified key. Otherwise, this method obtains the specified value.
42
     * @param mixed $key The key of the value to retrieve.
43
     * @param mixed $default Value to return if sequence does not contain value with specified key. Default: null.
44
     * @return mixed default value if the key is not found in the source sequence; otherwise, the value at the specified key in the source sequence.
45
     * @package YaLinqo\Pagination
46
     */
47
    public function elementAtOrDefault ($key, $default = null)
48
    {
49
        /** @var $it \Iterator|\ArrayAccess */
50
        $it = $this->getIterator();
51
52
        if ($it instanceof \ArrayAccess)
53
            return $it->offsetExists($key) ? $it->offsetGet($key) : $default;
54
55
        foreach ($it as $k => $v) {
56
            if ($k === $key)
57
                return $v;
58
        }
59
        return $default;
60
    }
61
62
    /**
63
     * Returns the first element of a sequence.
64
     * <p><b>Syntax</b>: first ()
65
     * <p>Returns the first element of a sequence.
66
     * <p>The first method throws an exception if source contains no elements. To instead return a default value when the source sequence is empty, use the {@link firstOrDefault} method.
67
     * <p><b>Syntax</b>: first (predicate {(v, k) ==> result})
68
     * <p>Returns the first element in a sequence that satisfies a specified condition.
69
     * <p>The first method throws an exception if no matching element is found in source. To instead return a default value when no matching element is found, use the {@link firstOrDefault} method.
70
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
71
     * @throws \UnexpectedValueException If source contains no matching elements.
72
     * @return mixed If predicate is null: the first element in the specified sequence. If predicate is not null: The first element in the sequence that passes the test in the specified predicate function.
73
     * @package YaLinqo\Pagination
74
     */
75
    public function first ($predicate = null)
76
    {
77
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
78
79
        foreach ($this as $k => $v) {
80
            if ($predicate($v, $k))
81
                return $v;
82
        }
83
        throw new \UnexpectedValueException(Errors::NO_MATCHES);
84
    }
85
86
    /**
87
     * Returns the first element of a sequence, or a default value if the sequence contains no elements.
88
     * <p><b>Syntax</b>: firstOrDefault ([default])
89
     * <p>Returns the first element of a sequence, or a default value if the sequence contains no elements.
90
     * <p><b>Syntax</b>: firstOrDefault ([default [, predicate {(v, k) ==> result}]])
91
     * <p>Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.
92
     * <p>If obtaining the default value is a costly operation, use {@link firstOrFallback} method to avoid overhead.
93
     * @param mixed $default A default value.
94
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
95
     * @return mixed If predicate is null: default value if source is empty; otherwise, the first element in source. If predicate is not null: default value if source is empty or if no element passes the test specified by predicate; otherwise, the first element in source that passes the test specified by predicate.
96
     * @package YaLinqo\Pagination
97
     */
98
    public function firstOrDefault ($default = null, $predicate = null)
99
    {
100
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
101
102
        foreach ($this as $k => $v) {
103
            if ($predicate($v, $k))
104
                return $v;
105
        }
106
        return $default;
107
    }
108
109
    /**
110
     * Returns the first element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
111
     * <p><b>Syntax</b>: firstOrFallback ([fallback {() ==> value}])
112
     * <p>Returns the first element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
113
     * <p><b>Syntax</b>: firstOrFallback ([fallback {() ==> value} [, predicate {(v, k) ==> result}]])
114
     * <p>Returns the first element of the sequence that satisfies a condition or the result of calling a fallback function if no such element is found.
115
     * <p>The fallback function is not executed if a matching element is found. Use the firstOrFallback method if obtaining the default value is a costly operation to avoid overhead. Otherwise, use {@link firstOrDefault}.
116
     * @param callable $fallback {() ==> value} A fallback function to return the default element.
117
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
118
     * @return mixed If predicate is null: the result of calling a fallback function if source is empty; otherwise, the first element in source. If predicate is not null: the result of calling a fallback function if source is empty or if no element passes the test specified by predicate; otherwise, the first element in source that passes the test specified by predicate.
119
     * @package YaLinqo\Pagination
120
     */
121
    public function firstOrFallback ($fallback, $predicate = null)
122
    {
123
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
124
125
        foreach ($this as $k => $v) {
126
            if ($predicate($v, $k))
127
                return $v;
128
        }
129
        return $fallback();
130
    }
131
132
    /**
133
     * Returns the last element of a sequence.
134
     * <p><b>Syntax</b>: last ()
135
     * <p>Returns the last element of a sequence.
136
     * <p>The last method throws an exception if source contains no elements. To instead return a default value when the source sequence is empty, use the {@link lastOrDefault} method.
137
     * <p><b>Syntax</b>: last (predicate {(v, k) ==> result})
138
     * <p>Returns the last element in a sequence that satisfies a specified condition.
139
     * <p>The last method throws an exception if no matching element is found in source. To instead return a default value when no matching element is found, use the {@link lastOrDefault} method.
140
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
141
     * @throws \UnexpectedValueException If source contains no matching elements.
142
     * @return mixed If predicate is null: the last element in the specified sequence. If predicate is not null: The last element in the sequence that passes the test in the specified predicate function.
143
     * @package YaLinqo\Pagination
144
     */
145
    public function last ($predicate = null)
146
    {
147
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
148
149
        $found = false;
150
        $value = null;
151
        foreach ($this as $k => $v) {
152
            if ($predicate($v, $k)) {
153
                $found = true;
154
                $value = $v;
155
            }
156
        }
157
        if (!$found)
158
            throw new \UnexpectedValueException(Errors::NO_MATCHES);
159
        return $value;
160
    }
161
162
    /**
163
     * Returns the last element of a sequence, or a default value if the sequence contains no elements.
164
     * <p><b>Syntax</b>: lastOrDefault ([default])
165
     * <p>Returns the last element of a sequence, or a default value if the sequence contains no elements.
166
     * <p><b>Syntax</b>: lastOrDefault ([default [, predicate {(v, k) ==> result}]])
167
     * <p>Returns the last element of the sequence that satisfies a condition or a default value if no such element is found.
168
     * <p>If obtaining the default value is a costly operation, use {@link lastOrFallback} method to avoid overhead.
169
     * @param mixed $default A default value.
170
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
171
     * @return mixed If predicate is null: default value if source is empty; otherwise, the last element in source. If predicate is not null: default value if source is empty or if no element passes the test specified by predicate; otherwise, the last element in source that passes the test specified by predicate.
172
     * @package YaLinqo\Pagination
173
     */
174
    public function lastOrDefault ($default = null, $predicate = null)
175
    {
176
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
177
178
        $found = false;
179
        $value = null;
180
        foreach ($this as $k => $v) {
181
            if ($predicate($v, $k)) {
182
                $found = true;
183
                $value = $v;
184
            }
185
        }
186
        return $found ? $value : $default;
187
    }
188
189
    /**
190
     * Returns the last element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
191
     * <p><b>Syntax</b>: lastOrFallback ([fallback {() ==> value}])
192
     * <p>Returns the last element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
193
     * <p><b>Syntax</b>: lastOrFallback ([fallback {() ==> value} [, predicate {(v, k) ==> result}]])
194
     * <p>Returns the last element of the sequence that satisfies a condition or the result of calling a fallback function if no such element is found.
195
     * <p>The fallback function is not executed if a matching element is found. Use the lastOrFallback method if obtaining the default value is a costly operation to avoid overhead. Otherwise, use {@link lastOrDefault}.
196
     * @param callable $fallback {() ==> value} A fallback function to return the default element.
197
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
198
     * @return mixed If predicate is null: the result of calling a fallback function if source is empty; otherwise, the last element in source. If predicate is not null: the result of calling a fallback function if source is empty or if no element passes the test specified by predicate; otherwise, the last element in source that passes the test specified by predicate.
199
     * @package YaLinqo\Pagination
200
     */
201
    public function lastOrFallback ($fallback, $predicate = null)
202
    {
203
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
204
205
        $found = false;
206
        $value = null;
207
        foreach ($this as $k => $v) {
208
            if ($predicate($v, $k)) {
209
                $found = true;
210
                $value = $v;
211
            }
212
        }
213
        return $found ? $value : $fallback();
214
    }
215
216
    /**
217
     * Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.
218
     * <p><b>Syntax</b>: single ()
219
     * <p>Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.
220
     * <p>The single method throws an exception if source contains no elements. To instead return a default value when the source sequence is empty, use the {@link singleOrDefault} method.
221
     * <p><b>Syntax</b>: single (predicate {(v, k) ==> result})
222
     * <p>Returns the only element of a sequence that satisfies a specified condition.
223
     * <p>The single method throws an exception if no matching element is found in source. To instead return a default value when no matching element is found, use the {@link singleOrDefault} method.
224
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
225
     * @throws \UnexpectedValueException If source contains no matching elements or more than one matching element.
226
     * @return mixed If predicate is null: the single element of the input sequence. If predicate is not null: The single element of the sequence that passes the test in the specified predicate function.
227
     * @package YaLinqo\Pagination
228
     */
229
    public function single ($predicate = null)
230
    {
231
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
232
233
        $found = false;
234
        $value = null;
235
        foreach ($this as $k => $v) {
236
            if ($predicate($v, $k)) {
237
                if ($found)
238
                    throw new \UnexpectedValueException(Errors::MANY_MATCHES);
239
                $found = true;
240
                $value = $v;
241
            }
242
        }
243
        if (!$found)
244
            throw new \UnexpectedValueException(Errors::NO_MATCHES);
245
        return $value;
246
    }
247
248
    /**
249
     * Returns the only element of a sequence, or a default value if the sequence contains no elements.
250
     * <p><b>Syntax</b>: singleOrDefault ([default])
251
     * <p>Returns the only element of a sequence, or a default value if the sequence contains no elements.
252
     * <p><b>Syntax</b>: singleOrDefault ([default [, predicate {(v, k) ==> result}]])
253
     * <p>Returns the only element of the sequence that satisfies a condition or a default value if no such element is found.
254
     * <p>If obtaining the default value is a costly operation, use {@link singleOrFallback} method to avoid overhead.
255
     * @param mixed $default A default value.
256
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
257
     * @throws \UnexpectedValueException If source contains more than one matching element.
258
     * @return mixed If predicate is null: default value if source is empty; otherwise, the single element of the source. If predicate is not null: default value if source is empty or if no element passes the test specified by predicate; otherwise, the single element of the source that passes the test specified by predicate.
259
     * @package YaLinqo\Pagination
260
     */
261
    public function singleOrDefault ($default = null, $predicate = null)
262
    {
263
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
264
265
        $found = false;
266
        $value = null;
267
        foreach ($this as $k => $v) {
268
            if ($predicate($v, $k)) {
269
                if ($found)
270
                    throw new \UnexpectedValueException(Errors::MANY_MATCHES);
271
                $found = true;
272
                $value = $v;
273
            }
274
        }
275
        return $found ? $value : $default;
276
    }
277
278
    /**
279
     * Returns the only element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
280
     * <p><b>Syntax</b>: singleOrFallback ([fallback {() ==> value}])
281
     * <p>Returns the only element of a sequence, or the result of calling a fallback function if the sequence contains no elements.
282
     * <p><b>Syntax</b>: singleOrFallback ([fallback {() ==> value} [, predicate {(v, k) ==> result}]])
283
     * <p>Returns the only element of the sequence that satisfies a condition or the result of calling a fallback function if no such element is found.
284
     * <p>The fallback function is not executed if a matching element is found. Use the singleOrFallback method if obtaining the default value is a costly operation to avoid overhead. Otherwise, use {@link singleOrDefault}.
285
     * @param callable $fallback {() ==> value} A fallback function to return the default element.
286
     * @param callable|null $predicate {(v, k) ==> result} A function to test each element for a condition. Default: true.
287
     * @throws \UnexpectedValueException If source contains more than one matching element.
288
     * @return mixed If predicate is null: the result of calling a fallback function if source is empty; otherwise, the single element of the source. If predicate is not null: the result of calling a fallback function if source is empty or if no element passes the test specified by predicate; otherwise, the single element of the source that passes the test specified by predicate.
289
     * @package YaLinqo\Pagination
290
     */
291
    public function singleOrFallback ($fallback, $predicate = null)
292
    {
293
        $predicate = Utils::createLambda($predicate, 'v,k', Functions::$true);
294
295
        $found = false;
296
        $value = null;
297
        foreach ($this as $k => $v) {
298
            if ($predicate($v, $k)) {
299
                if ($found)
300
                    throw new \UnexpectedValueException(Errors::MANY_MATCHES);
301
                $found = true;
302
                $value = $v;
303
            }
304
        }
305
        return $found ? $value : $fallback();
306
    }
307
308
    /**
309
     * Searches for the specified value and returns the key of the first occurrence.
310
     * <p><b>Syntax</b>: indexOf (value)
311
     * <p>To search for the zero-based index of the first occurence, call {@link toValues} method first.
312
     * @param mixed $value The value to locate in the sequence.
313
     * @return mixed The key of the first occurrence of value, if found; otherwise, null.
314
     * @package YaLinqo\Pagination
315
     */
316
    public function indexOf ($value)
317
    {
318
        foreach ($this as $k => $v) {
319
            if ($v === $value)
320
                return $k;
321
        }
322
        return null; // not -1
323
    }
324
325
    /**
326
     * Searches for the specified value and returns the key of the last occurrence.
327
     * <p><b>Syntax</b>: lastIndexOf (value)
328
     * <p>To search for the zero-based index of the last occurence, call {@link toValues} method first.
329
     * @param mixed $value The value to locate in the sequence.
330
     * @return mixed The key of the last occurrence of value, if found; otherwise, null.
331
     * @package YaLinqo\Pagination
332
     */
333
    public function lastIndexOf ($value)
334
    {
335
        $key = null;
336
        foreach ($this as $k => $v) {
337
            if ($v === $value)
338
                $key = $k;
339
        }
340
        return $key; // not -1
341
    }
342
343
    /**
344
     * Searches for an element that matches the conditions defined by the specified predicate, and returns the key of the first occurrence.
345
     * <p><b>Syntax</b>: findIndex (predicate {(v, k) ==> result})
346
     * <p>To search for the zero-based index of the first occurence, call {@link toValues} method first.
347
     * @param callable $predicate {(v, k) ==> result} A function that defines the conditions of the element to search for.
348
     * @return mixed The key of the first occurrence of an element that matches the conditions defined by predicate, if found; otherwise, null.
349
     * @package YaLinqo\Pagination
350
     */
351
    public function findIndex ($predicate)
352
    {
353
        $predicate = Utils::createLambda($predicate, 'v,k');
354
355
        foreach ($this as $k => $v) {
356
            if ($predicate($v, $k))
357
                return $k;
358
        }
359
        return null; // not -1
360
    }
361
362
    /**
363
     * Searches for an element that matches the conditions defined by the specified predicate, and returns the key of the last occurrence.
364
     * <p><b>Syntax</b>: findLastIndex (predicate {(v, k) ==> result})
365
     * <p>To search for the zero-based index of the last occurence, call {@link toValues} method first.
366
     * @param callable $predicate {(v, k) ==> result} A function that defines the conditions of the element to search for.
367
     * @return mixed The key of the last occurrence of an element that matches the conditions defined by predicate, if found; otherwise, null.
368
     * @package YaLinqo\Pagination
369
     */
370
    public function findLastIndex ($predicate)
371
    {
372
        $predicate = Utils::createLambda($predicate, 'v,k');
373
374
        $key = null;
375
        foreach ($this as $k => $v) {
376
            if ($predicate($v, $k))
377
                $key = $k;
378
        }
379
        return $key; // not -1
380
    }
381
382
    /**
383
     * Bypasses a specified number of elements in a sequence and then returns the remaining elements.
384
     * <p><b>Syntax</b>: skip (count)
385
     * <p>If source contains fewer than count elements, an empty sequence is returned. If count is less than or equal to zero, all elements of source are yielded.
386
     * <p>The {@link take} and skip methods are functional complements. Given a sequence coll and an integer n, concatenating the results of coll->take(n) and coll->skip(n) yields the same sequence as coll.
387
     * @param int $count The number of elements to skip before returning the remaining elements.
388
     * @return Enumerable A sequence that contains the elements that occur after the specified index in the input sequence.
389
     * @package YaLinqo\Pagination
390
     */
391
    public function skip ($count)
392
    {
393
        return new self(function () use ($count) {
394
            $it = $this->getIterator();
395
            $it->rewind();
396
            for ($i = 0; $i < $count && $it->valid(); ++$i)
397
                $it->next();
398
            while ($it->valid()) {
399
                yield $it->key() => $it->current();
400
                $it->next();
401
            }
402
        });
403
    }
404
405
    /**
406
     * Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.
407
     * <p><b>Syntax</b>: skipWhile (predicate {(v, k) ==> result})
408
     * <p>This method tests each element of source by using predicate and skips the element if the result is true. After the predicate function returns false for an element, that element and the remaining elements in source are yielded and there are no more invocations of predicate. If predicate returns true for all elements in the sequence, an empty sequence is returned.
409
     * <p>The {@link takeWhile} and skipWhile methods are functional complements. Given a sequence coll and a pure function p, concatenating the results of coll->takeWhile(p) and coll->skipWhile(p) yields the same sequence as coll.
410
     * @param callable $predicate {(v, k) ==> result} A function to test each element for a condition.
411
     * @return Enumerable A sequence that contains the elements from the input sequence starting at the first element in the linear series that does not pass the test specified by predicate.
412
     * @package YaLinqo\Pagination
413
     */
414
    public function skipWhile ($predicate)
415
    {
416
        $predicate = Utils::createLambda($predicate, 'v,k');
417
418
        return new self(function () use ($predicate) {
419
            $yielding = false;
420
            foreach ($this as $k => $v) {
421
                if (!$yielding && !$predicate($v, $k))
422
                    $yielding = true;
423
                if ($yielding)
424
                    yield $k => $v;
425
            }
426
        });
427
    }
428
429
    /**
430
     * Returns a specified number of contiguous elements from the start of a sequence.
431
     * <p><b>Syntax</b>: take (count)
432
     * <p>Take enumerates source and yields elements until count elements have been yielded or source contains no more elements. If count is less than or equal to zero, source is not enumerated and an empty sequence is returned.
433
     * <p>The take and {@link skip} methods are functional complements. Given a sequence coll and an integer n, concatenating the results of coll->take(n) and coll->skip(n) yields the same sequence as coll.
434
     * @param int $count The number of elements to return.
435
     * @return Enumerable A sequence that contains the specified number of elements from the start of the input sequence.
436
     * @package YaLinqo\Pagination
437
     */
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    public function take ($count)
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    {
440
        if ($count <= 0)
441
            return new self(new \EmptyIterator, false);
442
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        return new self(function () use ($count) {
444
            foreach ($this as $k => $v) {
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                yield $k => $v;
446
                if (--$count == 0)
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                    break;
448
            }
449
        });
450
    }
451
452
    /**
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     * Returns elements from a sequence as long as a specified condition is true.
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     * <p><b>Syntax</b>: takeWhile (predicate {(v, k) ==> result})
455
     * <p>The takeWhile method tests each element of source by using predicate and yields the element if the result is true. Enumeration stops when the predicate function returns false for an element or when source contains no more elements.
456
     * <p>The takeWhile and {@link skipWhile} methods are functional complements. Given a sequence coll and a pure function p, concatenating the results of coll->takeWhile(p) and coll->skipWhile(p) yields the same sequence as coll.
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     * @param callable $predicate {(v, k) ==> result} A function to test each element for a condition.
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     * @return Enumerable A sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes.
459
     * @package YaLinqo\Pagination
460
     */
461
    public function takeWhile ($predicate)
462
    {
463
        $predicate = Utils::createLambda($predicate, 'v,k');
464
465
        return new self(function () use ($predicate) {
466
            foreach ($this as $k => $v) {
467
                if (!$predicate($v, $k))
468
                    break;
469
                yield $k => $v;
470
            }
471
        });
472
    }
473
474
    /**
475
     * @return \Iterator
476
     */
477
    public abstract function getIterator ();
478
}