VictoriaMetrics/vendor/github.com/xrash/smetrics/soundex.go

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package smetrics
import (
"strings"
)
// The Soundex encoding. It is a phonetic algorithm that considers how the words sound in English. Soundex maps a string to a 4-byte code consisting of the first letter of the original string and three numbers. Strings that sound similar should map to the same code.
func Soundex(s string) string {
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b := strings.Builder{}
b.Grow(4)
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p := s[0]
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if p <= 'z' && p >= 'a' {
p -= 32 // convert to uppercase
}
b.WriteByte(p)
n := 0
for i := 1; i < len(s); i++ {
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c := s[i]
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if c <= 'z' && c >= 'a' {
c -= 32 // convert to uppercase
} else if c < 'A' || c > 'Z' {
continue
}
if c == p {
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continue
}
p = c
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switch c {
case 'B', 'P', 'F', 'V':
c = '1'
case 'C', 'S', 'K', 'G', 'J', 'Q', 'X', 'Z':
c = '2'
case 'D', 'T':
c = '3'
case 'L':
c = '4'
case 'M', 'N':
c = '5'
case 'R':
c = '6'
default:
continue
}
b.WriteByte(c)
n++
if n == 3 {
break
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}
}
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for i := n; i < 3; i++ {
b.WriteByte('0')
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}
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return b.String()
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}