lotus/lib/rlepluslazy/rleplus.go
Jakub Sztandera 32a1940c57
Replace rleplus with rlepluslazy
License: MIT
Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>
2019-12-07 15:48:20 +01:00

195 lines
3.4 KiB
Go

package rlepluslazy
import (
"errors"
"fmt"
"golang.org/x/xerrors"
)
const Version = 0
var (
ErrWrongVersion = errors.New("invalid RLE+ version")
ErrDecode = fmt.Errorf("invalid encoding for RLE+ version %d", Version)
)
type RLE struct {
buf []byte
}
func FromBuf(buf []byte) (RLE, error) {
rle := RLE{buf: buf}
if len(buf) > 0 && buf[0]&3 != Version {
return RLE{}, xerrors.Errorf("could not create RLE+ for a buffer: %w", ErrWrongVersion)
}
_, err := rle.Count()
if err != nil {
return RLE{}, err
}
return rle, nil
}
func (rle *RLE) RunIterator() (RunIterator, error) {
source, err := DecodeRLE(rle.buf)
return source, err
}
func (rle *RLE) Count() (uint64, error) {
it, err := rle.RunIterator()
if err != nil {
return 0, err
}
return Count(it)
}
/*
type change struct {
set bool
reset bool
index uint64
}
func (c change) valid() bool {
return c.reset || c.set
}
func (rle *RLE) RunIterator() (RunIterator, error) {
if err != nil {
return nil, err
}
if len(rle.changes) == 0 {
return source, nil
}
ch := rle.changes
// using stable sort because we want to preserve change order
sort.SliceStable(ch, func(i int, j int) bool {
return ch[i].index < ch[j].index
})
for i := range ch {
if i+1 >= len(ch) {
break
}
if ch[i].index == ch[i+1].index {
ch[i].set = false
ch[i].reset = false
}
}
sets := make([]uint64, 0, len(ch)/2)
clears := make([]uint64, 0, len(ch)/2)
for _, c := range ch {
if c.set {
sets = append(sets, c.index)
} else if c.reset {
clears = append(clears, c.index)
}
}
setRuns, err := RunsFromSlice(sets)
if err != nil {
return nil, err
}
clearRuns, err := RunsFromSlice(clears)
if err != nil {
return nil, err
}
it := &chit{source: source, sets: setRuns, clears: clearRuns}
return nil, nil
}
type chit struct {
source RunIterator
sets RunIterator
clears RunIterator
next Run
nextSource Run
nextSet Run
nextClear Run
}
func (it *chit) prep() error {
var err error
if !it.nextSource.Valid() && it.source.HasNext() {
it.nextSource, err = it.source.NextRun()
if err != nil {
return err
}
}
if !it.nextSet.Valid() && it.sets.HasNext() {
it.nextSet, err = it.sets.NextRun()
if err != nil {
return err
}
}
if !it.nextClear.Valid() && it.clears.HasNext() {
it.nextClear, err = it.clears.NextRun()
if err != nil {
return err
}
}
for len(it.changes) != 0 && !it.changes[0].valid() {
it.changes = it.changes[1:]
}
var ch change
if len(it.changes) != 0 {
ch = it.changes[0]
}
if it.source.HasNext() {
var err error
it.nextRun, err = it.source.NextRun()
if err != nil {
return err
}
}
if ch.valid() && ch.index < it.runIndex+it.nextRun.Len {
if ch.set != it.nextRun.Val {
// split run
whole := it.nextRun
it.nextRun.Len = ch.index - it.runIndex
}
// if we are here then change was valid so len(it.changes) != 0
it.changes = it.changes[1:]
} else {
it.runIndex = it.runIndex + it.nextRun.Len
}
return nil
}
func (it *chit) HasNext() bool {
return it.nextRun.Valid()
}
func (it *chit) NextRun() (Run, error) {
return it.nextRun, it.prep()
}
func (rle *RLE) Set(index uint64) {
rle.changes = append(rle.changes, change{set: true, index: index})
}
func (rle *RLE) Clear(index uint64) {
rle.changes = append(rle.changes, change{reset: true, index: index})
}
func (rle *RLE) Merge(other *RLE) RunIterator {
return nil
}
*/