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707f3a69db
Natural sorting is needed for sort_by_label_natural() and sort_by_label_natural_desc() functions in MetricsQL - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6192 and https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6256 Natural sorting will be also used by `| sort ...` pipe in VictoriaLogs - see https://docs.victoriametrics.com/victorialogs/logsql/#sort-pipe
111 lines
1.9 KiB
Go
111 lines
1.9 KiB
Go
package stringsutil
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import (
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"math"
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)
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// LessNatural returns true if a is less than b using natural sort comparison.
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//
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// See https://en.wikipedia.org/wiki/Natural_sort_order
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func LessNatural(a, b string) bool {
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isReverse := false
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for {
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if len(a) > len(b) {
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a, b = b, a
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isReverse = !isReverse
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}
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// Skip common prefix except of decimal digits
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i := 0
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for i < len(a) {
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cA := a[i]
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cB := b[i]
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if cA >= '0' && cA <= '9' {
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if cB >= '0' && cB <= '9' {
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break
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}
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return !isReverse
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}
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if cB >= '0' && cB <= '9' {
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return isReverse
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}
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if cA != cB {
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// This should work properly for utf8 bytes in the middle of encoded unicode char, since:
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// - utf8 bytes for multi-byte chars are bigger than decimal digit chars
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// - sorting of utf8-encoded strings works properly thanks to utf8 properties
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if isReverse {
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return cB < cA
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}
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return cA < cB
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}
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i++
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}
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a = a[i:]
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b = b[i:]
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if len(a) == 0 {
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if isReverse {
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return false
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}
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return len(b) > 0
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}
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// Collect digit prefixes for a and b and then compare them.
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iA := 1
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nA := uint64(a[0] - '0')
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for iA < len(a) {
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c := a[iA]
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if c < '0' || c > '9' {
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break
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}
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if nA > (math.MaxUint64-9)/10 {
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// Too big integer. Fall back to string comparison
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if isReverse {
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return b < a
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}
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return a < b
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}
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nA *= 10
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nA += uint64(c - '0')
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iA++
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}
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iB := 1
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nB := uint64(b[0] - '0')
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for iB < len(b) {
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c := b[iB]
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if c < '0' || c > '9' {
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break
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}
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if nB > (math.MaxUint64-9)/10 {
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// Too big integer. Fall back to string comparison
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if isReverse {
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return b < a
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}
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return a < b
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}
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nB *= 10
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nB += uint64(c - '0')
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iB++
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}
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if nA != nB {
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if isReverse {
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return nB < nA
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}
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return nA < nB
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}
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if iA != iB {
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if isReverse {
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return iB < iA
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}
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return iA < iB
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}
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a = a[iA:]
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b = b[iB:]
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}
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}
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