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gitea/vendor/github.com/blevesearch/go-porterstemmer/porterstemmer.go
2017-01-25 10:43:02 +08:00

839 lines
16 KiB
Go

package porterstemmer
import (
// "log"
"unicode"
)
func isConsonant(s []rune, i int) bool {
//DEBUG
//log.Printf("isConsonant: [%+v]", string(s[i]))
result := true
switch s[i] {
case 'a', 'e', 'i', 'o', 'u':
result = false
case 'y':
if 0 == i {
result = true
} else {
result = !isConsonant(s, i-1)
}
default:
result = true
}
return result
}
func measure(s []rune) uint {
// Initialize.
lenS := len(s)
result := uint(0)
i := 0
// Short Circuit.
if 0 == lenS {
/////////// RETURN
return result
}
// Ignore (potential) consonant sequence at the beginning of word.
for isConsonant(s, i) {
//DEBUG
//log.Printf("[measure([%s])] Eat Consonant [%d] -> [%s]", string(s), i, string(s[i]))
i++
if i >= lenS {
/////////////// RETURN
return result
}
}
// For each pair of a vowel sequence followed by a consonant sequence, increment result.
Outer:
for i < lenS {
for !isConsonant(s, i) {
//DEBUG
//log.Printf("[measure([%s])] VOWEL [%d] -> [%s]", string(s), i, string(s[i]))
i++
if i >= lenS {
/////////// BREAK
break Outer
}
}
for isConsonant(s, i) {
//DEBUG
//log.Printf("[measure([%s])] CONSONANT [%d] -> [%s]", string(s), i, string(s[i]))
i++
if i >= lenS {
result++
/////////// BREAK
break Outer
}
}
result++
}
// Return
return result
}
func hasSuffix(s, suffix []rune) bool {
lenSMinusOne := len(s) - 1
lenSuffixMinusOne := len(suffix) - 1
if lenSMinusOne <= lenSuffixMinusOne {
return false
} else if s[lenSMinusOne] != suffix[lenSuffixMinusOne] { // I suspect checking this first should speed this function up in practice.
/////// RETURN
return false
} else {
for i := 0; i < lenSuffixMinusOne; i++ {
if suffix[i] != s[lenSMinusOne-lenSuffixMinusOne+i] {
/////////////// RETURN
return false
}
}
}
return true
}
func containsVowel(s []rune) bool {
lenS := len(s)
for i := 0; i < lenS; i++ {
if !isConsonant(s, i) {
/////////// RETURN
return true
}
}
return false
}
func hasRepeatDoubleConsonantSuffix(s []rune) bool {
// Initialize.
lenS := len(s)
result := false
// Do it!
if 2 > lenS {
result = false
} else if s[lenS-1] == s[lenS-2] && isConsonant(s, lenS-1) { // Will using isConsonant() cause a problem with "YY"?
result = true
} else {
result = false
}
// Return,
return result
}
func hasConsonantVowelConsonantSuffix(s []rune) bool {
// Initialize.
lenS := len(s)
result := false
// Do it!
if 3 > lenS {
result = false
} else if isConsonant(s, lenS-3) && !isConsonant(s, lenS-2) && isConsonant(s, lenS-1) {
result = true
} else {
result = false
}
// Return
return result
}
func step1a(s []rune) []rune {
// Initialize.
var result []rune = s
lenS := len(s)
// Do it!
if suffix := []rune("sses"); hasSuffix(s, suffix) {
lenTrim := 2
subSlice := s[:lenS-lenTrim]
result = subSlice
} else if suffix := []rune("ies"); hasSuffix(s, suffix) {
lenTrim := 2
subSlice := s[:lenS-lenTrim]
result = subSlice
} else if suffix := []rune("ss"); hasSuffix(s, suffix) {
result = s
} else if suffix := []rune("s"); hasSuffix(s, suffix) {
lenSuffix := 1
subSlice := s[:lenS-lenSuffix]
result = subSlice
}
// Return.
return result
}
func step1b(s []rune) []rune {
// Initialize.
var result []rune = s
lenS := len(s)
// Do it!
if suffix := []rune("eed"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 0 < m {
lenTrim := 1
result = s[:lenS-lenTrim]
}
} else if suffix := []rune("ed"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
if containsVowel(subSlice) {
if suffix2 := []rune("at"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
} else if suffix2 := []rune("bl"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
} else if suffix2 := []rune("iz"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
} else if c := subSlice[len(subSlice)-1]; 'l' != c && 's' != c && 'z' != c && hasRepeatDoubleConsonantSuffix(subSlice) {
lenTrim := 1
lenSubSlice := len(subSlice)
result = subSlice[:lenSubSlice-lenTrim]
} else if c := subSlice[len(subSlice)-1]; 1 == measure(subSlice) && hasConsonantVowelConsonantSuffix(subSlice) && 'w' != c && 'x' != c && 'y' != c {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
result[len(result)-1] = 'e'
} else {
result = subSlice
}
}
} else if suffix := []rune("ing"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
if containsVowel(subSlice) {
if suffix2 := []rune("at"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
result[len(result)-1] = 'e'
} else if suffix2 := []rune("bl"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
result[len(result)-1] = 'e'
} else if suffix2 := []rune("iz"); hasSuffix(subSlice, suffix2) {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
result[len(result)-1] = 'e'
} else if c := subSlice[len(subSlice)-1]; 'l' != c && 's' != c && 'z' != c && hasRepeatDoubleConsonantSuffix(subSlice) {
lenTrim := 1
lenSubSlice := len(subSlice)
result = subSlice[:lenSubSlice-lenTrim]
} else if c := subSlice[len(subSlice)-1]; 1 == measure(subSlice) && hasConsonantVowelConsonantSuffix(subSlice) && 'w' != c && 'x' != c && 'y' != c {
lenTrim := -1
result = s[:lenS-lenSuffix-lenTrim]
result[len(result)-1] = 'e'
} else {
result = subSlice
}
}
}
// Return.
return result
}
func step1c(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if 2 > lenS {
/////////// RETURN
return result
}
if 'y' == s[lenS-1] && containsVowel(s[:lenS-1]) {
result[lenS-1] = 'i'
} else if 'Y' == s[lenS-1] && containsVowel(s[:lenS-1]) {
result[lenS-1] = 'I'
}
// Return.
return result
}
func step2(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if suffix := []rune("ational"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-5] = 'e'
result = result[:lenS-4]
}
} else if suffix := []rune("tional"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = result[:lenS-2]
}
} else if suffix := []rune("enci"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-1] = 'e'
}
} else if suffix := []rune("anci"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-1] = 'e'
}
} else if suffix := []rune("izer"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-1]
}
} else if suffix := []rune("bli"); hasSuffix(s, suffix) { // --DEPARTURE--
// } else if suffix := []rune("abli") ; hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-1] = 'e'
}
} else if suffix := []rune("alli"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-2]
}
} else if suffix := []rune("entli"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-2]
}
} else if suffix := []rune("eli"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-2]
}
} else if suffix := []rune("ousli"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-2]
}
} else if suffix := []rune("ization"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-5] = 'e'
result = s[:lenS-4]
}
} else if suffix := []rune("ation"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-3] = 'e'
result = s[:lenS-2]
}
} else if suffix := []rune("ator"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-2] = 'e'
result = s[:lenS-1]
}
} else if suffix := []rune("alism"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-3]
}
} else if suffix := []rune("iveness"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-4]
}
} else if suffix := []rune("fulness"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-4]
}
} else if suffix := []rune("ousness"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-4]
}
} else if suffix := []rune("aliti"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result = s[:lenS-3]
}
} else if suffix := []rune("iviti"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-3] = 'e'
result = result[:lenS-2]
}
} else if suffix := []rune("biliti"); hasSuffix(s, suffix) {
if 0 < measure(s[:lenS-len(suffix)]) {
result[lenS-5] = 'l'
result[lenS-4] = 'e'
result = result[:lenS-3]
}
} else if suffix := []rune("logi"); hasSuffix(s, suffix) { // --DEPARTURE--
if 0 < measure(s[:lenS-len(suffix)]) {
lenTrim := 1
result = s[:lenS-lenTrim]
}
}
// Return.
return result
}
func step3(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if suffix := []rune("icate"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
if 0 < measure(s[:lenS-lenSuffix]) {
result = result[:lenS-3]
}
} else if suffix := []rune("ative"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 0 < m {
result = subSlice
}
} else if suffix := []rune("alize"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
if 0 < measure(s[:lenS-lenSuffix]) {
result = result[:lenS-3]
}
} else if suffix := []rune("iciti"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
if 0 < measure(s[:lenS-lenSuffix]) {
result = result[:lenS-3]
}
} else if suffix := []rune("ical"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
if 0 < measure(s[:lenS-lenSuffix]) {
result = result[:lenS-2]
}
} else if suffix := []rune("ful"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 0 < m {
result = subSlice
}
} else if suffix := []rune("ness"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 0 < m {
result = subSlice
}
}
// Return.
return result
}
func step4(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if suffix := []rune("al"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = result[:lenS-lenSuffix]
}
} else if suffix := []rune("ance"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = result[:lenS-lenSuffix]
}
} else if suffix := []rune("ence"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = result[:lenS-lenSuffix]
}
} else if suffix := []rune("er"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ic"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("able"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ible"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ant"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ement"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ment"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ent"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ion"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
c := subSlice[len(subSlice)-1]
if 1 < m && ('s' == c || 't' == c) {
result = subSlice
}
} else if suffix := []rune("ou"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ism"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ate"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("iti"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ous"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ive"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
} else if suffix := []rune("ize"); hasSuffix(s, suffix) {
lenSuffix := len(suffix)
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
}
// Return.
return result
}
func step5a(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if 'e' == s[lenS-1] {
lenSuffix := 1
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
} else if 1 == m {
if c := subSlice[len(subSlice)-1]; !(hasConsonantVowelConsonantSuffix(subSlice) && 'w' != c && 'x' != c && 'y' != c) {
result = subSlice
}
}
}
// Return.
return result
}
func step5b(s []rune) []rune {
// Initialize.
lenS := len(s)
result := s
// Do it!
if 2 < lenS && 'l' == s[lenS-2] && 'l' == s[lenS-1] {
lenSuffix := 1
subSlice := s[:lenS-lenSuffix]
m := measure(subSlice)
if 1 < m {
result = subSlice
}
}
// Return.
return result
}
func StemString(s string) string {
// Convert string to []rune
runeArr := []rune(s)
// Stem.
runeArr = Stem(runeArr)
// Convert []rune to string
str := string(runeArr)
// Return.
return str
}
func Stem(s []rune) []rune {
// Initialize.
lenS := len(s)
// Short circuit.
if 0 == lenS {
/////////// RETURN
return s
}
// Make all runes lowercase.
for i := 0; i < lenS; i++ {
s[i] = unicode.ToLower(s[i])
}
// Stem
result := StemWithoutLowerCasing(s)
// Return.
return result
}
func StemWithoutLowerCasing(s []rune) []rune {
// Initialize.
lenS := len(s)
// Words that are of length 2 or less is already stemmed.
// Don't do anything.
if 2 >= lenS {
/////////// RETURN
return s
}
// Stem
s = step1a(s)
s = step1b(s)
s = step1c(s)
s = step2(s)
s = step3(s)
s = step4(s)
s = step5a(s)
s = step5b(s)
// Return.
return s
}