47 lines
1.1 KiB
Go
47 lines
1.1 KiB
Go
|
package missinggo
|
||
|
|
|
||
|
|
// A RunLengthEncoder counts successive duplicate elements and emits the
|
||
|
|
// element and the run length when the element changes or the encoder is
|
||
|
|
// flushed.
|
||
|
|
type RunLengthEncoder interface {
|
||
|
|
// Add a series of identical elements to the stream.
|
||
|
|
Append(element interface{}, count uint64)
|
||
|
|
// Emit the current element and its count if non-zero without waiting for
|
||
|
|
// the element to change.
|
||
|
|
Flush()
|
||
|
|
}
|
||
|
|
|
||
|
|
type runLengthEncoder struct {
|
||
|
|
eachRun func(element interface{}, count uint64)
|
||
|
|
element interface{}
|
||
|
|
count uint64
|
||
|
|
}
|
||
|
|
|
||
|
|
// Creates a new RunLengthEncoder. eachRun is called when an element and its
|
||
|
|
// count is emitted, per the RunLengthEncoder interface.
|
||
|
|
func NewRunLengthEncoder(eachRun func(element interface{}, count uint64)) RunLengthEncoder {
|
||
|
|
return &runLengthEncoder{
|
||
|
|
eachRun: eachRun,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (me *runLengthEncoder) Append(element interface{}, count uint64) {
|
||
|
|
if element == me.element {
|
||
|
|
me.count += count
|
||
|
|
return
|
||
|
|
}
|
||
|
|
if me.count != 0 {
|
||
|
|
me.eachRun(me.element, me.count)
|
||
|
|
}
|
||
|
|
me.count = count
|
||
|
|
me.element = element
|
||
|
|
}
|
||
|
|
|
||
|
|
func (me *runLengthEncoder) Flush() {
|
||
|
|
if me.count == 0 {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
me.eachRun(me.element, me.count)
|
||
|
|
me.count = 0
|
||
|
|
}
|