Initial

1 files changed, 142 insertions, 0 deletions

diff --git a/StemmerRu/stemmer.go b/StemmerRu/stemmer.go
new file mode 100644
index 0000000..f15281b
--- /dev/null
+++ b/StemmerRu/stemmer.go
@@ -0,0 +1,142 @@
+package StemmerRu
+
+import (
+	"strings"
+)
+
+var (
+	perfectiveGerund = [][]string{{`в`, `вши`, `вшись`}, {`ив`, `ивши`, `ившись`, `ыв`, `ывши`, `ывшись`}}
+	adjective        = []string{`ее`, `ие`, `ые`, `ое`, `ими`, `ыми`, `ей`, `ий`, `ый`, `ой`, `ем`, `им`, `ым`, `ом`, `его`, `ого`, `ему`, `ому`, `их`, `ых`, `ую`, `юю`, `ая`, `яя`, `ою`, `ею`}
+	participle       = [][]string{{`ем`, `нн`, `вш`, `ющ`, `щ`}, {`ивш`, `ывш`, `ующ`}}
+	reflexive        = []string{`ся`, `сь`}
+	verb             = [][]string{{`ла`, `на`, `ете`, `йте`, `ли`, `й`, `л`, `ем`, `н`, `ло`, `но`, `ет`, `ют`, `ны`, `ть`, `ешь`, `нно`}, {`ила`, `ыла`, `ена`, `ейте`, `уйте`, `ите`, `или`, `ыли`, `ей`, `уй`, `ил`, `ыл`, `им`, `ым`, `ен`, `ило`, `ыло`, `ено`, `ят`, `ует`, `уют`, `ит`, `ыт`, `ены`, `ить`, `ыть`, `ишь`, `ую`, `ю`}}
+	noun             = []string{`а`, `ев`, `ов`, `ие`, `ье`, `е`, `иями`, `ями`, `ами`, `еи`, `ии`, `и`, `ией`, `ей`, `ой`, `ий`, `й`, `иям`, `ям`, `ием`, `ем`, `ам`, `ом`, `о`, `у`, `ах`, `иях`, `ях`, `ы`, `ь`, `ию`, `ью`, `ю`, `ия`, `ья`, `я`}
+	superlative      = []string{`ейш`, `ейше`}
+	derivational     = []string{`ост`, `ость`}
+
+	vowels = `аеиоуыэюя`
+)
+
+func StemWord(word string) string {
+
+	word = strings.Replace(word, `ё`, `е`, -1)
+
+	RVpos := getRVPart(word)
+
+	if RVpos == -1 {
+		return word
+	}
+
+
+	R1pos := getRNPart(word, 0)
+	R2pos := getRNPart(word, R1pos)
+	if (R2pos < RVpos) {
+		R2pos = 0
+	} else {
+		R2pos -= RVpos
+	}
+
+	suffix := string([]rune(word)[RVpos:])
+	prefix := string([]rune(word)[:RVpos])
+
+	// Step 1
+	suffix, isTrimmed := trimSuffix(suffix, perfectiveGerund[1], perfectiveGerund[0])
+	if !isTrimmed {
+		suffix, isTrimmed = trimSuffix(suffix, reflexive, nil)
+		suffix, isTrimmed = trimAdjectival(suffix)
+		if !isTrimmed {
+			suffix, isTrimmed = trimSuffix(suffix, verb[1], verb[0])
+			if !isTrimmed {
+				suffix, _ = trimSuffix(suffix, noun, nil)
+			}
+		}
+	}
+
+	// Step 2
+	suffix = strings.TrimSuffix(suffix, `и`)
+
+	// Step 3
+	if R2pos < len([]rune(suffix)) {
+		R2suffix := string([]rune(suffix)[R2pos:])
+		R2prefix := string([]rune(suffix)[:R2pos])
+		R2suffix, _ = trimSuffix(R2suffix, derivational, nil)
+		suffix = R2prefix + R2suffix
+	}
+
+	// Step 4
+	suffix, isTrimmed = trimNN(suffix)
+	if !isTrimmed {
+		suffix, isTrimmed = trimSuffix(suffix, superlative, nil)
+		if isTrimmed {
+			suffix, _ = trimNN(suffix)
+		} else {
+			suffix = strings.TrimSuffix(suffix, `ь`)
+		}
+	}
+
+	return prefix + suffix
+}
+
+func trimNN(word string) (string, bool) {
+	if strings.HasSuffix(word, `нн`) {
+		return strings.TrimSuffix(word, `нн`) + `н`, true
+	}
+
+	return word, false
+}
+
+func trimAdjectival(word string) (string, bool) {
+	isTrimmedParticiple := false
+	word, isTrimmedAdjective := trimSuffix(word, adjective, nil)
+	if isTrimmedAdjective {
+		word, isTrimmedParticiple = trimSuffix(word, participle[1], participle[0])
+	}
+
+	return word, isTrimmedAdjective || isTrimmedParticiple
+}
+
+func trimSuffix(word string, suffixes []string, suffixes2 []string) (string, bool) {
+	for _, suffix := range suffixes {
+		if strings.HasSuffix(word, suffix) {
+			return strings.TrimSuffix(word, suffix), true
+		}
+	}
+	if suffixes2 != nil {
+		for _, suffix := range suffixes2 {
+			if strings.HasSuffix(word, `а`+suffix) ||
+				strings.HasSuffix(word, `я`+suffix) {
+				return strings.TrimSuffix(word, suffix), true
+			}
+		}
+	}
+
+	return word, false
+}
+
+func isVowel(char rune) bool {
+	return strings.Contains(vowels, string(char))
+}
+
+func getRVPart(word string) int {
+	chars := []rune(word)
+	for idx, char := range chars {
+		if isVowel(char) {
+			return idx + 1
+		}
+	}
+
+	return -1
+}
+
+func getRNPart(word string, startPos int) int {
+	chars := []rune(word)[startPos:]
+	for idx, char := range chars {
+		if idx+2 < len(chars) {
+			if isVowel(char) && !isVowel(chars[idx+1]) {
+				return startPos + idx + 2
+			}
+		}
+	}
+
+	return startPos
+}