func curs(pairs ...interface{}) queryCursor {
if len(pairs)%2 != 0 {
panic("curs() takes only even pairs")
}
pre := &bytes.Buffer{}
if _, err := cmpbin.WriteUint(pre, uint64(len(pairs)/2)); err != nil {
panic(err)
}
post := serialize.Invertible(&bytes.Buffer{})
for i := 0; i < len(pairs); i += 2 {
k, v := pairs[i].(string), pairs[i+1]
col, err := dstore.ParseIndexColumn(k)
if err != nil {
panic(err)
}
post.SetInvert(col.Descending)
if err := serialize.WriteIndexColumn(pre, col); err != nil {
panic(err)
}
if err := serialize.WriteProperty(post, serialize.WithoutContext, prop(v)); err != nil {
panic(err)
}
}
return queryCursor(serialize.Join(pre.Bytes(), post.Bytes()))
}
func parseSuffix(ns string, suffixFormat []ds.IndexColumn, suffix []byte, count int) (raw [][]byte, decoded []ds.Property) {
buf := serialize.Invertible(bytes.NewBuffer(suffix))
decoded = make([]ds.Property, len(suffixFormat))
raw = make([][]byte, len(suffixFormat))
err := error(nil)
for i := range decoded {
if count > 0 && i > count {
break
}
needInvert := suffixFormat[i].Direction == ds.DESCENDING
buf.SetInvert(needInvert)
decoded[i], err = serialize.ReadProperty(buf, serialize.WithoutContext, globalAppID, ns)
memoryCorruption(err)
offset := len(suffix) - buf.Len()
raw[i] = suffix[:offset]
suffix = suffix[offset:]
if needInvert {
raw[i] = invert(raw[i])
}
}
return
}
// permute calls cb for each index row, in the sorted order of the rows.
func (s indexRowGen) permute(collSetFn func(k, v []byte)) {
iVec := make([]int, len(s.propVec))
iVecLim := make([]int, len(s.propVec))
incPos := func() bool {
for i := len(iVec) - 1; i >= 0; i-- {
var done bool
var newVal int
if s.orders[i] == ds.ASCENDING {
newVal = (iVec[i] + 1) % iVecLim[i]
done = newVal != 0
} else {
newVal = (iVec[i] - 1)
if newVal < 0 {
newVal = iVecLim[i] - 1
} else {
done = true
}
}
iVec[i] = newVal
if done {
return true
}
}
return false
}
for i, sps := range s.propVec {
iVecLim[i] = len(sps)
}
for i := range iVec {
if s.orders[i] == ds.DESCENDING {
iVec[i] = iVecLim[i] - 1
}
}
for {
bufsiz := 0
for pvalSliceIdx, pvalIdx := range iVec {
bufsiz += len(s.propVec[pvalSliceIdx][pvalIdx])
}
buf := serialize.Invertible(bytes.NewBuffer(make([]byte, 0, bufsiz)))
for pvalSliceIdx, pvalIdx := range iVec {
data := s.propVec[pvalSliceIdx][pvalIdx]
buf.SetInvert(s.orders[pvalSliceIdx] == ds.DESCENDING)
buf.Write(data)
}
collSetFn(buf.Bytes(), []byte{})
if !incPos() {
break
}
}
}
func curs(pairs ...interface{}) queryCursor {
if len(pairs)%2 != 0 {
panic("curs() takes only even pairs")
}
pre := &bytes.Buffer{}
cmpbin.WriteUint(pre, uint64(len(pairs)/2))
post := serialize.Invertible(&bytes.Buffer{})
for i := 0; i < len(pairs); i += 2 {
k, v := pairs[i].(string), pairs[i+1]
col := dsS.IndexColumn{Property: k}
post.SetInvert(false)
if k[0] == '-' {
post.SetInvert(false)
col.Property = k[1:]
col.Direction = dsS.DESCENDING
}
serialize.WriteIndexColumn(pre, col)
serialize.WriteProperty(post, serialize.WithoutContext, prop(v))
}
return queryCursor(bjoin(pre.Bytes(), post.Bytes()))
}