forked from pingcap/tidb
-
Notifications
You must be signed in to change notification settings - Fork 2
/
array_iter.go
184 lines (155 loc) · 3.34 KB
/
array_iter.go
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
// Copyright (c) 2014, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package iterator
import (
"github.com/pingcap/goleveldb/leveldb/util"
)
// BasicArray is the interface that wraps basic Len and Search method.
type BasicArray interface {
// Len returns length of the array.
Len() int
// Search finds smallest index that point to a key that is greater
// than or equal to the given key.
Search(key []byte) int
}
// Array is the interface that wraps BasicArray and basic Index method.
type Array interface {
BasicArray
// Index returns key/value pair with index of i.
Index(i int) (key, value []byte)
}
// Array is the interface that wraps BasicArray and basic Get method.
type ArrayIndexer interface {
BasicArray
// Get returns a new data iterator with index of i.
Get(i int) Iterator
}
type basicArrayIterator struct {
util.BasicReleaser
array BasicArray
pos int
err error
}
func (i *basicArrayIterator) Valid() bool {
return i.pos >= 0 && i.pos < i.array.Len() && !i.Released()
}
func (i *basicArrayIterator) First() bool {
if i.Released() {
i.err = ErrIterReleased
return false
}
if i.array.Len() == 0 {
i.pos = -1
return false
}
i.pos = 0
return true
}
func (i *basicArrayIterator) Last() bool {
if i.Released() {
i.err = ErrIterReleased
return false
}
n := i.array.Len()
if n == 0 {
i.pos = 0
return false
}
i.pos = n - 1
return true
}
func (i *basicArrayIterator) Seek(key []byte) bool {
if i.Released() {
i.err = ErrIterReleased
return false
}
n := i.array.Len()
if n == 0 {
i.pos = 0
return false
}
i.pos = i.array.Search(key)
if i.pos >= n {
return false
}
return true
}
func (i *basicArrayIterator) Next() bool {
if i.Released() {
i.err = ErrIterReleased
return false
}
i.pos++
if n := i.array.Len(); i.pos >= n {
i.pos = n
return false
}
return true
}
func (i *basicArrayIterator) Prev() bool {
if i.Released() {
i.err = ErrIterReleased
return false
}
i.pos--
if i.pos < 0 {
i.pos = -1
return false
}
return true
}
func (i *basicArrayIterator) Error() error { return i.err }
type arrayIterator struct {
basicArrayIterator
array Array
pos int
key, value []byte
}
func (i *arrayIterator) updateKV() {
if i.pos == i.basicArrayIterator.pos {
return
}
i.pos = i.basicArrayIterator.pos
if i.Valid() {
i.key, i.value = i.array.Index(i.pos)
} else {
i.key = nil
i.value = nil
}
}
func (i *arrayIterator) Key() []byte {
i.updateKV()
return i.key
}
func (i *arrayIterator) Value() []byte {
i.updateKV()
return i.value
}
type arrayIteratorIndexer struct {
basicArrayIterator
array ArrayIndexer
}
func (i *arrayIteratorIndexer) Get() Iterator {
if i.Valid() {
return i.array.Get(i.basicArrayIterator.pos)
}
return nil
}
// NewArrayIterator returns an iterator from the given array.
func NewArrayIterator(array Array) Iterator {
return &arrayIterator{
basicArrayIterator: basicArrayIterator{array: array, pos: -1},
array: array,
pos: -1,
}
}
// NewArrayIndexer returns an index iterator from the given array.
func NewArrayIndexer(array ArrayIndexer) IteratorIndexer {
return &arrayIteratorIndexer{
basicArrayIterator: basicArrayIterator{array: array, pos: -1},
array: array,
}
}