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