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// 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/syndtr/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
}
func (i *basicArrayIterator) Valid() bool {
return i.pos >= 0 && i.pos < i.array.Len()
}
func (i *basicArrayIterator) First() bool {
if i.array.Len() == 0 {
i.pos = -1
return false
}
i.pos = 0
return true
}
func (i *basicArrayIterator) Last() bool {
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 {
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 {
i.pos++
if n := i.array.Len(); i.pos >= n {
i.pos = n
return false
}
return true
}
func (i *basicArrayIterator) Prev() bool {
i.pos--
if i.pos < 0 {
i.pos = -1
return false
}
return true
}
func (i *basicArrayIterator) Error() error { return nil }
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,
}
}
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