1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
|
<?php
/**
* This file is part of the ramsey/collection library
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*
* @copyright Copyright (c) Ben Ramsey <ben@benramsey.com>
* @license http://opensource.org/licenses/MIT MIT
*/
declare(strict_types=1);
namespace Ramsey\Collection;
use Ramsey\Collection\Exception\InvalidArgumentException;
use Ramsey\Collection\Exception\NoSuchElementException;
/**
* This class provides a basic implementation of `DoubleEndedQueueInterface`, to
* minimize the effort required to implement this interface.
*/
class DoubleEndedQueue extends Queue implements DoubleEndedQueueInterface
{
/**
* Index of the last element in the queue.
*
* @var int
*/
private $tail = -1;
/**
* Sets the given value to the given offset in the queue.
*
* Since arbitrary offsets may not be manipulated in a queue, this method
* serves only to fulfill the `ArrayAccess` interface requirements. It is
* invoked by other operations when adding values to the queue.
*
* @link http://php.net/manual/en/arrayaccess.offsetset.php ArrayAccess::offsetSet()
*
* @param mixed|null $offset The offset is ignored and is treated as `null`.
* @param mixed $value The value to set at the given offset.
*
* @throws InvalidArgumentException when the value does not match the
* specified type for this queue.
*/
public function offsetSet($offset, $value): void
{
if ($this->checkType($this->getType(), $value) === false) {
throw new InvalidArgumentException(
'Value must be of type ' . $this->getType() . '; value is '
. $this->toolValueToString($value)
);
}
$this->tail++;
$this->data[$this->tail] = $value;
}
/**
* Ensures that the specified element is inserted at the front of this queue.
*
* @see self::offerFirst()
*
* @param mixed $element The element to add to this queue.
*
* @return bool `true` if this queue changed as a result of the call.
*
* @throws InvalidArgumentException when the value does not match the
* specified type for this queue.
*/
public function addFirst($element): bool
{
if ($this->checkType($this->getType(), $element) === false) {
throw new InvalidArgumentException(
'Value must be of type ' . $this->getType() . '; value is '
. $this->toolValueToString($element)
);
}
$this->index--;
$this->data[$this->index] = $element;
return true;
}
/**
* Ensures that the specified element in inserted at the end of this queue.
*
* @see Queue::add()
*
* @param mixed $element The element to add to this queue.
*
* @return bool `true` if this queue changed as a result of the call.
*
* @throws InvalidArgumentException when the value does not match the
* specified type for this queue.
*/
public function addLast($element): bool
{
return $this->add($element);
}
/**
* Inserts the specified element at the front this queue.
*
* @see self::addFirst()
*
* @param mixed $element The element to add to this queue.
*
* @return bool `true` if the element was added to this queue, else `false`.
*/
public function offerFirst($element): bool
{
try {
return $this->addFirst($element);
} catch (InvalidArgumentException $e) {
return false;
}
}
/**
* Inserts the specified element at the end this queue.
*
* @see self::addLast()
* @see Queue::offer()
*
* @param mixed $element The element to add to this queue.
*
* @return bool `true` if the element was added to this queue, else `false`.
*/
public function offerLast($element): bool
{
return $this->offer($element);
}
/**
* Retrieves and removes the head of this queue.
*
* This method differs from `pollFirst()` only in that it throws an
* exception if this queue is empty.
*
* @see self::pollFirst()
* @see Queue::remove()
*
* @return mixed the head of this queue.
*
* @throws NoSuchElementException if this queue is empty.
*/
public function removeFirst()
{
return $this->remove();
}
/**
* Retrieves and removes the tail of this queue.
*
* This method differs from `pollLast()` only in that it throws an exception
* if this queue is empty.
*
* @see self::pollLast()
*
* @return mixed the tail of this queue.
*
* @throws NoSuchElementException if this queue is empty.
*/
public function removeLast()
{
if ($this->count() === 0) {
throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
}
$tail = $this[$this->tail];
unset($this[$this->tail]);
$this->tail--;
return $tail;
}
/**
* Retrieves and removes the head of this queue, or returns `null` if this
* queue is empty.
*
* @see self::removeFirst()
*
* @return mixed|null the head of this queue, or `null` if this queue is empty.
*/
public function pollFirst()
{
return $this->poll();
}
/**
* Retrieves and removes the tail of this queue, or returns `null` if this
* queue is empty.
*
* @see self::removeLast()
*
* @return mixed|null the tail of this queue, or `null` if this queue is empty.
*/
public function pollLast()
{
if ($this->count() === 0) {
return null;
}
$tail = $this[$this->tail];
unset($this[$this->tail]);
$this->tail--;
return $tail;
}
/**
* Retrieves, but does not remove, the head of this queue.
*
* This method differs from `peekFirst()` only in that it throws an
* exception if this queue is empty.
*
* @see self::peekFirst()
* @see Queue::element()
*
* @return mixed the head of this queue.
*
* @throws NoSuchElementException if this queue is empty.
*/
public function firstElement()
{
return $this->element();
}
/**
* Retrieves, but does not remove, the tail of this queue.
*
* This method differs from `peekLast()` only in that it throws an exception
* if this queue is empty.
*
* @see self::peekLast()
*
* @return mixed the tail of this queue.
*
* @throws NoSuchElementException if this queue is empty.
*/
public function lastElement()
{
if ($this->count() === 0) {
throw new NoSuchElementException('Can\'t return element from Queue. Queue is empty.');
}
return $this->data[$this->tail];
}
/**
* Retrieves, but does not remove, the head of this queue, or returns `null`
* if this queue is empty.
*
* @see self::firstElement()
* @see Queue::peek()
*
* @return mixed|null the head of this queue, or `null` if this queue is empty.
*/
public function peekFirst()
{
return $this->peek();
}
/**
* Retrieves, but does not remove, the tail of this queue, or returns `null`
* if this queue is empty.
*
* @see self::lastElement()
*
* @return mixed|null the tail of this queue, or `null` if this queue is empty
*/
public function peekLast()
{
if ($this->count() === 0) {
return null;
}
return $this->data[$this->tail];
}
}
|
