redis/iterator.go

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package redis
import "sync"
type Scanner struct {
client cmdable
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*ScanCmd
}
// Iterator creates a new ScanIterator.
func (s Scanner) Iterator() *ScanIterator {
return &ScanIterator{
Scanner: s,
}
}
// ScanIterator is used to incrementally iterate over a collection of elements.
// It's safe for concurrent use by multiple goroutines.
type ScanIterator struct {
mu sync.Mutex // protects Scanner and pos
Scanner
pos int
}
// Err returns the last iterator error, if any.
func (it *ScanIterator) Err() error {
it.mu.Lock()
err := it.ScanCmd.Err()
it.mu.Unlock()
return err
}
// Next advances the cursor and returns true if more values can be read.
func (it *ScanIterator) Next() bool {
it.mu.Lock()
defer it.mu.Unlock()
// Instantly return on errors.
if it.ScanCmd.Err() != nil {
return false
}
// Advance cursor, check if we are still within range.
if it.pos < len(it.ScanCmd.page) {
it.pos++
return true
}
// Return if there is more data to fetch.
if it.ScanCmd.cursor == 0 {
return false
}
// Fetch next page.
it.ScanCmd._args[1] = it.ScanCmd.cursor
it.ScanCmd.reset()
it.client.process(it.ScanCmd)
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if it.ScanCmd.Err() != nil {
return false
}
it.pos = 1
return len(it.ScanCmd.page) > 0
}
// Val returns the key/field at the current cursor position.
func (it *ScanIterator) Val() string {
var v string
it.mu.Lock()
if it.ScanCmd.Err() == nil && it.pos > 0 && it.pos <= len(it.ScanCmd.page) {
v = it.ScanCmd.page[it.pos-1]
}
it.mu.Unlock()
return v
}