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1.5 KiB

package db
import (
"bytes"
)
func cp(bz []byte) (ret []byte) {
ret = make([]byte, len(bz))
copy(ret, bz)
return ret
}
// Returns a slice of the same length (big endian)
// except incremented by one.
// Returns nil on overflow (e.g. if bz bytes are all 0xFF)
// CONTRACT: len(bz) > 0
func cpIncr(bz []byte) (ret []byte) {
if len(bz) == 0 {
panic("cpIncr expects non-zero bz length")
}
ret = cp(bz)
for i := len(bz) - 1; i >= 0; i-- {
if ret[i] < byte(0xFF) {
ret[i]++
return
}
ret[i] = byte(0x00)
if i == 0 {
// Overflow
return nil
}
}
return nil
}
// Returns a slice of the same length (big endian)
// except decremented by one.
// Returns nil on underflow (e.g. if bz bytes are all 0x00)
// CONTRACT: len(bz) > 0
func cpDecr(bz []byte) (ret []byte) {
if len(bz) == 0 {
panic("cpDecr expects non-zero bz length")
}
ret = cp(bz)
for i := len(bz) - 1; i >= 0; i-- {
if ret[i] > byte(0x00) {
ret[i]--
return
}
ret[i] = byte(0xFF)
if i == 0 {
// Underflow
return nil
}
}
return nil
}
// See DB interface documentation for more information.
func IsKeyInDomain(key, start, end []byte, isReverse bool) bool {
if !isReverse {
if bytes.Compare(key, start) < 0 {
return false
}
if end != nil && bytes.Compare(end, key) <= 0 {
return false
}
return true
} else {
if start != nil && bytes.Compare(start, key) < 0 {
return false
}
if end != nil && bytes.Compare(key, end) <= 0 {
return false
}
return true
}
}