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package skate
import "strings"
type runestring []rune
// A safe way to index a runestring. It will return a null rune if you try
// to index outside of the bounds of the runestring.
func (r *runestring) SafeAt(pos int) rune {
if pos < 0 || pos >= len(*r) {
return 0
} else {
return (*r)[pos]
}
}
// A safe way to obtain a substring of a runestring. It will return a null
// string ("") if you index somewhere outside its bounds.
func (r *runestring) SafeSubstr(pos int, length int) string {
if pos < 0 || pos > len(*r) || (pos+length) > len(*r) {
return ""
} else {
return string((*r)[pos : pos+length])
}
}
// Delete characters at positions pos. It will do nothing if you provide
// an index outside the bounds of the runestring.
func (r *runestring) Del(pos ...int) {
for _, i := range pos {
if i >= 0 && i <= len(*r) {
*r = append((*r)[:i], (*r)[i+1:]...)
}
}
}
// A helper to determine if any substrings exist within the given runestring.
func (r *runestring) Contains(start int, length int, criteria ...string) bool {
substring := r.SafeSubstr(start, length)
for _, c := range criteria {
if substring == c {
return true
}
}
return false
}
func cleanInput(input string) string {
return strings.ToUpper(strings.TrimSpace(input))
}
func isVowelNoY(c rune) bool {
switch c {
case 'A', 'E', 'I', 'O', 'U':
return true
default:
return false
}
}
// NYSIIS computes the NYSIIS phonetic encoding of the input string. It is a
// modification of the traditional Soundex algorithm.
func NYSIIS(s1 string) string {
cleans1 := runestring(cleanInput(s1))
input := runestring(make([]rune, 0, len(s1)))
// The output can't be larger than the string itself
output := runestring(make([]rune, 0, len(s1)))
// 0. Remove all non-ASCII characters
for _, v := range cleans1 {
if v >= 65 && v <= 90 {
input = append(input, v)
}
}
if len(input) == 0 {
return ""
}
// 1. Transcoding first characters
switch input[0] {
case 'M':
if input.SafeSubstr(0, 3) == "MAC" {
// MAC -> MCC
input[1] = 'C'
}
case 'K':
if input.SafeSubstr(0, 2) == "KN" {
// KN -> NN
input[0] = 'N'
} else {
// K -> C
input[0] = 'C'
}
case 'P':
next := input.SafeAt(1)
if next == 'H' {
// PH -> FF
input[0] = 'F'
input[1] = 'F'
} else if next == 'F' {
// PF -> FF
input[0] = 'F'
}
case 'S':
if input.SafeSubstr(0, 3) == "SCH" {
input[1] = 'S'
input[2] = 'S'
}
}
// 2. Transcoding last characters
switch input.SafeSubstr(len(input)-2, 2) {
case "EE", "IE":
// EE, IE -> Y
input.Del(len(input) - 2)
input[len(input)-1] = 'Y'
case "DT", "RT", "RD", "NT", "ND":
// DT, RT, RD, NT, ND -> D
input.Del(len(input) - 2)
input[len(input)-1] = 'D'
}
// 3. First character of key = first character of name
output = append(output, input[0])
last := input[0]
for i := 1; i < len(input); i++ {
c := input[i]
switch c {
case 'A', 'I', 'O', 'U':
// A, E, I, O, U -> A (E is separate)
input[i] = 'A'
case 'E':
// EV -> AF, else A
if input.SafeAt(i+1) == 'V' {
input[i+1] = 'F'
}
input[i] = 'A'
case 'Q':
// Q -> G
input[i] = 'G'
case 'Z':
// Z -> S
input[i] = 'S'
case 'M':
// M -> N
input[i] = 'N'
case 'K':
// KN -> N, else K -> C
if input.SafeAt(i+1) == 'N' {
input.Del(i)
} else {
input[i] = 'C'
}
case 'S':
// SCH -> SSS
if input.SafeSubstr(i, 3) == "SCH" {
input[i+1] = 'S'
input[i+2] = 'S'
}
case 'P':
// PH -> FF
if input.SafeAt(i+1) == 'H' {
input[i] = 'F'
input[i+1] = 'F'
}
case 'H':
// H -> $(previous character) if previous character or
// next character is a non-vowel
prev := input.SafeAt(i - 1)
next := input.SafeAt(i + 1)
if !isVowelNoY(prev) || !isVowelNoY(next) {
input[i] = prev
}
case 'W':
prev := input.SafeAt(i - 1)
if isVowelNoY(prev) {
input[i] = prev
}
}
if input[i] != last && input[i] != 0 {
output = append(output, input[i])
}
last = input[i]
}
// have to be careful here because we've already added the first
// key value
if len(output) > 1 {
// remove trailing s
if output.SafeAt(len(output)-1) == 'S' {
output.Del(len(output) - 1)
}
// trailing AY -> Y
if len(output) > 2 && output.SafeSubstr(len(output)-2, 2) == "AY" {
output.Del(len(output) - 2)
}
// trailing A -> remove it
if output.SafeAt(len(output)-1) == 'A' {
output.Del(len(output) - 1)
}
}
if len(output) > 6 {
return string(output[0:6])
} else {
return string(output)
}
}
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