|
1
|
|
|
<?php |
|
2
|
|
|
|
|
3
|
|
|
namespace itertools; |
|
4
|
|
|
|
|
5
|
|
|
use IteratorIterator; |
|
6
|
|
|
|
|
7
|
|
|
/** |
|
8
|
|
|
* This iterator is able to prefetch its values and cache them. |
|
9
|
|
|
* This you to look ahead of the current iteration position. |
|
10
|
|
|
*/ |
|
11
|
|
|
class CachingIterator extends IteratorIterator |
|
12
|
|
|
{ |
|
13
|
|
|
const NO_REWIND = 'NO_REWIND'; |
|
14
|
|
|
const CACHE_ISSUED_REWIND = 'CACHE_ISSUED_REWIND'; |
|
15
|
|
|
const OUTER_ISSUED_REWIND = 'OUTER_ISSUED_REWIND'; |
|
16
|
|
|
|
|
17
|
|
|
protected $cache = array(); |
|
18
|
|
|
protected $rewindStatus = self::NO_REWIND; |
|
19
|
|
|
|
|
20
|
|
|
public function __construct($innerIterator) |
|
21
|
|
|
{ |
|
22
|
|
|
parent::__construct(IterUtil::asIterator($innerIterator)); |
|
23
|
|
|
} |
|
24
|
|
|
|
|
25
|
|
|
protected function uncachedKey() |
|
26
|
|
|
{ |
|
27
|
|
|
return $this->getInnerIterator()->key(); |
|
28
|
|
|
} |
|
29
|
|
|
|
|
30
|
|
|
protected function uncachedCurrent() |
|
31
|
|
|
{ |
|
32
|
|
|
return $this->getInnerIterator()->current(); |
|
33
|
|
|
} |
|
34
|
|
|
|
|
35
|
|
|
protected function uncachedValid() |
|
36
|
|
|
{ |
|
37
|
|
|
return $this->getInnerIterator()->valid(); |
|
38
|
|
|
} |
|
39
|
|
|
|
|
40
|
|
|
protected function uncachedRewind() |
|
41
|
|
|
{ |
|
42
|
|
|
return $this->getInnerIterator()->rewind(); |
|
43
|
|
|
} |
|
44
|
|
|
|
|
45
|
|
|
protected function uncachedNext() |
|
46
|
|
|
{ |
|
47
|
|
|
return $this->getInnerIterator()->next(); |
|
48
|
|
|
} |
|
49
|
|
|
|
|
50
|
|
|
public function cacheUpTo($count) |
|
51
|
|
|
{ |
|
52
|
|
|
if(self::NO_REWIND == $this->rewindStatus) { |
|
53
|
|
|
$this->uncachedRewind(); |
|
54
|
|
|
$this->rewindStatus = self::CACHE_ISSUED_REWIND; |
|
55
|
|
|
} |
|
56
|
|
|
while(count($this->cache) < $count && $this->uncachedValid()) { |
|
57
|
|
|
$this->cache[] = (object) array('key' => $this->uncachedKey(), 'current' => $this->uncachedCurrent()); |
|
58
|
|
|
$this->uncachedNext(); |
|
59
|
|
|
} |
|
60
|
|
|
} |
|
61
|
|
|
|
|
62
|
|
|
public function rewind() |
|
63
|
|
|
{ |
|
64
|
|
|
if(self::CACHE_ISSUED_REWIND == $this->rewindStatus) { |
|
65
|
|
|
$this->rewindStatus = self::OUTER_ISSUED_REWIND; |
|
66
|
|
|
return; |
|
67
|
|
|
} |
|
68
|
|
|
$this->cache = array(); |
|
69
|
|
|
$this->uncachedRewind(); |
|
70
|
|
|
$this->rewindStatus = self::OUTER_ISSUED_REWIND; |
|
71
|
|
|
} |
|
72
|
|
|
|
|
73
|
|
|
public function key() |
|
74
|
|
|
{ |
|
75
|
|
|
$this->cacheUpTo(1); |
|
76
|
|
|
return reset($this->cache)->key; |
|
77
|
|
|
} |
|
78
|
|
|
|
|
79
|
|
|
public function current() |
|
80
|
|
|
{ |
|
81
|
|
|
$this->cacheUpTo(1); |
|
82
|
|
|
return reset($this->cache)->current; |
|
83
|
|
|
} |
|
84
|
|
|
|
|
85
|
|
|
public function next() |
|
86
|
|
|
{ |
|
87
|
|
|
array_shift($this->cache); |
|
88
|
|
|
} |
|
89
|
|
|
|
|
90
|
|
|
public function hasNext($offset = 1) |
|
91
|
|
|
{ |
|
92
|
|
|
$this->cacheUpTo($offset); |
|
93
|
|
|
return count($this->cache) >= $offset; |
|
94
|
|
|
} |
|
95
|
|
|
|
|
96
|
|
|
public function valid() |
|
97
|
|
|
{ |
|
98
|
|
|
$this->cacheUpTo(1); |
|
99
|
|
|
return count($this->cache) > 0; |
|
100
|
|
|
} |
|
101
|
|
|
} |
|
102
|
|
|
|
|
103
|
|
|
|
SuRaMoN /
itertools
