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virtual.go
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virtual.go
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package index
import (
"errors"
"strconv"
"strings"
)
type partFunc func(string, *vIndex) (int64, int64, error)
var (
virtual = map[string]partFunc{
"size": SizePart,
}
)
func Has(t string) bool {
if _, has := virtual[t]; has {
return true
}
return false
}
type vIndex struct {
T string
path string
size int64
ChunkSize int64
partF partFunc
}
func NewVirtual(t string, p string, s int64, c int64) *vIndex {
if partFunc, has := virtual[t]; has {
return &vIndex{
T: "virtual",
path: p,
size: s,
ChunkSize: c,
partF: partFunc,
}
}
return &vIndex{}
}
func (v *vIndex) Part(p string, q string, r int64) (pos int64, length int64, err error) {
return v.partF(p, v)
}
func SizePart(part string, v *vIndex) (pos int64, length int64, err error) {
if strings.Contains(part, "-") {
startend := strings.Split(part, "-")
start, startEr := strconv.ParseInt(startend[0], 10, 64)
end, endEr := strconv.ParseInt(startend[1], 10, 64)
if startEr != nil || endEr != nil || start <= 0 || (start-1)*v.ChunkSize > v.size || end <= 0 || (end-1)*v.ChunkSize > v.size {
err = errors.New("")
return
}
pos = (start - 1) * v.ChunkSize
fullReads := (end-1)*v.ChunkSize - (start-1)*v.ChunkSize
if fullReads+v.ChunkSize+pos > v.size {
length = fullReads + (v.size - (pos + fullReads))
} else {
length = fullReads + v.ChunkSize
}
} else {
p, er := strconv.ParseInt(part, 10, 64)
if er != nil || p <= 0 || (p-1)*v.ChunkSize > v.size {
err = errors.New("")
return
}
pos = (p - 1) * v.ChunkSize
if v.size-pos < v.ChunkSize {
length = v.size - pos
} else {
length = v.ChunkSize
}
}
return
}
func (v *vIndex) Set(i map[string]interface{}) {
if cv, has := i["ChunkSize"]; has {
if chunksize, ok := cv.(int64); ok {
v.ChunkSize = chunksize
}
}
return
}
func (v *vIndex) Type() string {
return v.T
}
func (v *vIndex) GetLength() int64 {
return v.size
}
// Empty functions to fulfil interface
func (v *vIndex) Append(a []int64) {
return
}
func (v *vIndex) Range(string, string, int64) ([][]int64, error) {
return nil, nil
}