63 lines
1 KiB
Go
63 lines
1 KiB
Go
package smetrics
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import (
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"strings"
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)
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// 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.
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func Soundex(s string) string {
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b := strings.Builder{}
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b.Grow(4)
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p := s[0]
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if p <= 'z' && p >= 'a' {
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p -= 32 // convert to uppercase
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}
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b.WriteByte(p)
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n := 0
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for i := 1; i < len(s); i++ {
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c := s[i]
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if c <= 'z' && c >= 'a' {
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c -= 32 // convert to uppercase
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} else if c < 'A' || c > 'Z' {
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continue
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}
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if c == p {
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continue
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}
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p = c
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switch c {
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case 'B', 'P', 'F', 'V':
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c = '1'
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case 'C', 'S', 'K', 'G', 'J', 'Q', 'X', 'Z':
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c = '2'
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case 'D', 'T':
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c = '3'
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case 'L':
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c = '4'
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case 'M', 'N':
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c = '5'
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case 'R':
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c = '6'
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default:
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continue
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}
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b.WriteByte(c)
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n++
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if n == 3 {
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break
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}
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}
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for i := n; i < 3; i++ {
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b.WriteByte('0')
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}
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return b.String()
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}
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