Golang SnowballWord.ReplaceSuffixRunes方法代码示例

// Step 3 is the stemming of various longer sufficies
// found in R1.
//
func step3(w *snowballword.SnowballWord) bool {

	suffix, suffixRunes := w.FirstSuffix(
		"ational", "tional", "alize", "icate", "ative",
		"iciti", "ical", "ful", "ness",
	)

	// If it is not in R1, do nothing
	if suffix == "" || len(suffixRunes) > len(w.RS)-w.R1start {
		return false
	}

	// Handle special cases where we're not just going to
	// replace the suffix with another suffix: there are
	// other things we need to do.
	//
	if suffix == "ative" {

		// If in R2, delete.
		//
		if len(w.RS)-w.R2start >= 5 {
			w.RemoveLastNRunes(len(suffixRunes))
			return true
		}
		return false
	}

	// Handle a suffix that was found, which is going
	// to be replaced with a different suffix.
	//
	var repl string
	switch suffix {
	case "ational":
		repl = "ate"
	case "tional":
		repl = "tion"
	case "alize":
		repl = "al"
	case "icate", "iciti", "ical":
		repl = "ic"
	case "ful", "ness":
		repl = ""
	}
	w.ReplaceSuffixRunes(suffixRunes, []rune(repl), true)
	return true

}

// Step 1a is normalization of various special "s"-endings.
//
func step1a(w *snowballword.SnowballWord) bool {

	suffix, suffixRunes := w.FirstSuffix("sses", "ied", "ies", "us", "ss", "s")
	switch suffix {

	case "sses":

		// Replace by ss
		w.ReplaceSuffixRunes(suffixRunes, []rune("ss"), true)
		return true

	case "ies", "ied":

		// Replace by i if preceded by more than one letter,
		// otherwise by ie (so ties -> tie, cries -> cri).

		var repl string
		if len(w.RS) > 4 {
			repl = "i"
		} else {
			repl = "ie"
		}
		w.ReplaceSuffixRunes(suffixRunes, []rune(repl), true)
		return true

	case "us", "ss":

		// Do nothing
		return false

	case "s":

		// Delete if the preceding word part contains a vowel
		// not immediately before the s (so gas and this retain
		// the s, gaps and kiwis lose it)
		//
		for i := 0; i < len(w.RS)-2; i++ {
			if isLowerVowel(w.RS[i]) {
				w.RemoveLastNRunes(len(suffixRunes))
				return true
			}
		}
	}
	return false
}

// Step 2 is the stemming of various endings found in
// R1 including "al", "ness", and "li".
//
func step2(w *snowballword.SnowballWord) bool {

	// Possible sufficies for this step, longest first.
	suffix, suffixRunes := w.FirstSuffix(
		"ational", "fulness", "iveness", "ization", "ousness",
		"biliti", "lessli", "tional", "alism", "aliti", "ation",
		"entli", "fulli", "iviti", "ousli", "anci", "abli",
		"alli", "ator", "enci", "izer", "bli", "ogi", "li",
	)

	// If it is not in R1, do nothing
	if suffix == "" || len(suffixRunes) > len(w.RS)-w.R1start {
		return false
	}

	// Handle special cases where we're not just going to
	// replace the suffix with another suffix: there are
	// other things we need to do.
	//
	switch suffix {

	case "li":

		// Delete if preceded by a valid li-ending. Valid li-endings inlude the
		// following charaters: cdeghkmnrt. (Note, the unicode code points for
		// these characters are, respectively, as follows:
		// 99 100 101 103 104 107 109 110 114 116)
		//
		rsLen := len(w.RS)
		if rsLen >= 3 {
			switch w.RS[rsLen-3] {
			case 99, 100, 101, 103, 104, 107, 109, 110, 114, 116:
				w.RemoveLastNRunes(len(suffixRunes))
				return true
			}
		}
		return false

	case "ogi":

		// Replace by og if preceded by l.
		// (Note, the unicode code point for l is 108)
		//
		rsLen := len(w.RS)
		if rsLen >= 4 && w.RS[rsLen-4] == 108 {
			w.ReplaceSuffixRunes(suffixRunes, []rune("og"), true)
		}
		return true
	}

	// Handle a suffix that was found, which is going
	// to be replaced with a different suffix.
	//
	var repl string
	switch suffix {
	case "tional":
		repl = "tion"
	case "enci":
		repl = "ence"
	case "anci":
		repl = "ance"
	case "abli":
		repl = "able"
	case "entli":
		repl = "ent"
	case "izer", "ization":
		repl = "ize"
	case "ational", "ation", "ator":
		repl = "ate"
	case "alism", "aliti", "alli":
		repl = "al"
	case "fulness":
		repl = "ful"
	case "ousli", "ousness":
		repl = "ous"
	case "iveness", "iviti":
		repl = "ive"
	case "biliti", "bli":
		repl = "ble"
	case "fulli":
		repl = "ful"
	case "lessli":
		repl = "less"
	}
	w.ReplaceSuffixRunes(suffixRunes, []rune(repl), true)
	return true

}

// Step 4 is the cleaning up of residual suffixes.
//
func step4(word *snowballword.SnowballWord) bool {

	hadChange := false

	if word.String() == "voudrion" {
		log.Println("...", word)
	}

	// If the word ends s (unicode code point 115),
	// not preceded by a, i, o, u, è or s, delete it.
	//
	if idx := len(word.RS) - 1; idx >= 1 && word.RS[idx] == 115 {
		switch word.RS[idx-1] {

		case 97, 105, 111, 117, 232, 115:

			// Do nothing, preceded by a, i, o, u, è or s
			return false

		default:
			word.RemoveLastNRunes(1)
			hadChange = true

		}
	}

	// Note: all the following are restricted to the RV region.

	// Search for the longest among the following suffixes in RV.
	//
	suffix, suffixRunes := word.FirstSuffixIn(word.RVstart, len(word.RS),
		"Ière", "ière", "Ier", "ier", "ion", "e", "ë",
	)

	switch suffix {
	case "":
		return hadChange
	case "ion":

		// Delete if in R2 and preceded by s or t in RV

		const sLen int = 3 // equivalently, len(suffixRunes)
		idx := len(word.RS) - sLen - 1
		if word.FitsInR2(sLen) && idx >= 0 && word.FitsInRV(sLen+1) {
			if word.RS[idx] == 115 || word.RS[idx] == 116 {
				word.RemoveLastNRunes(sLen)
				return true
			}
		}
		return hadChange

	case "ier", "ière", "Ier", "Ière":
		// Replace with i
		word.ReplaceSuffixRunes(suffixRunes, []rune("i"), true)
		return true

	case "e":
		word.RemoveLastNRunes(1)
		return true

	case "ë":

		// If preceded by gu (unicode code point 103 & 117), delete
		idx := len(word.RS) - 1
		if idx >= 2 && word.RS[idx-2] == 103 && word.RS[idx-1] == 117 {
			word.RemoveLastNRunes(1)
			return true
		}
		return hadChange
	}

	return true
}

// Step 1 is the removal of standard suffixes
//
func step1(word *snowballword.SnowballWord) bool {
	suffix, suffixRunes := word.FirstSuffix(
		"issements", "issement", "atrices", "utions", "usions", "logies",
		"emment", "ements", "atrice", "ations", "ateurs", "amment", "ution",
		"usion", "ments", "logie", "istes", "ismes", "iqUes", "euses",
		"ences", "ement", "ation", "ateur", "ances", "ables", "ment",
		"ités", "iste", "isme", "iqUe", "euse", "ence", "eaux", "ance",
		"able", "ives", "ité", "eux", "aux", "ive", "ifs", "if",
	)

	if suffix == "" {
		return false
	}

	isInR1 := (word.R1start <= len(word.RS)-len(suffixRunes))
	isInR2 := (word.R2start <= len(word.RS)-len(suffixRunes))
	isInRV := (word.RVstart <= len(word.RS)-len(suffixRunes))

	// Handle simple replacements & deletions in R2 first
	if isInR2 {

		// Handle simple replacements in R2
		repl := ""
		switch suffix {
		case "logie", "logies":
			repl = "log"
		case "usion", "ution", "usions", "utions":
			repl = "u"
		case "ence", "ences":
			repl = "ent"
		}
		if repl != "" {
			word.ReplaceSuffixRunes(suffixRunes, []rune(repl), true)
			return true
		}

		// Handle simple deletions in R2
		switch suffix {
		case "ance", "iqUe", "isme", "able", "iste", "eux", "ances", "iqUes", "ismes", "ables", "istes":
			word.RemoveLastNRunes(len(suffixRunes))
			return true
		}
	}

	// Handle simple replacements in RV
	if isInRV {

		// NOTE: these are "special" suffixes in that
		// we must still do steps 2a and 2b of the
		// French stemmer even when these suffixes are
		// found in step1.  Therefore, we are returning
		// `false` here.

		repl := ""
		switch suffix {
		case "amment":
			repl = "ant"
		case "emment":
			repl = "ent"
		}
		if repl != "" {
			word.ReplaceSuffixRunes(suffixRunes, []rune(repl), true)
			return false
		}

		// Delete if preceded by a vowel that is also in RV
		if suffix == "ment" || suffix == "ments" {
			idx := len(word.RS) - len(suffixRunes) - 1
			if idx >= word.RVstart && isLowerVowel(word.RS[idx]) {
				word.RemoveLastNRunes(len(suffixRunes))
				return false
			}
			return false
		}
	}

	// Handle all the other "special" cases.  All of these
	// return true immediately after changing the word.
	//
	switch suffix {
	case "eaux":

		// Replace with eau
		word.ReplaceSuffixRunes(suffixRunes, []rune("eau"), true)
		return true

	case "aux":

		// Replace with al if in R1
		if isInR1 {
			word.ReplaceSuffixRunes(suffixRunes, []rune("al"), true)
			return true
		}

	case "euse", "euses":

		// Delete if in R2, else replace by eux if in R1
		if isInR2 {
//.........这里部分代码省略.........

// Step 0 is the removal of attached pronouns
//
func step0(word *snowballword.SnowballWord) bool {

	// Search for the longest among the following suffixes
	suffix1, suffix1Runes := word.FirstSuffixIn(word.RVstart, len(word.RS),
		"selas", "selos", "sela", "selo", "las", "les",
		"los", "nos", "me", "se", "la", "le", "lo",
	)

	// If the suffix empty or not in RV, we have nothing to do.
	if suffix1 == "" {
		return false
	}

	// We'll remove suffix1, if comes after one of the following
	suffix2, suffix2Runes := word.FirstSuffixIn(word.RVstart, len(word.RS)-len(suffix1),
		"iéndo", "iendo", "yendo", "ando", "ándo",
		"ár", "ér", "ír", "ar", "er", "ir",
	)
	switch suffix2 {
	case "":

		// Nothing to do
		return false

	case "iéndo", "ándo", "ár", "ér", "ír":

		// In these cases, deletion is followed by removing
		// the acute accent (e.g., haciéndola -> haciendo).

		var suffix2repl string
		switch suffix2 {
		case "":
			return false
		case "iéndo":
			suffix2repl = "iendo"
		case "ándo":
			suffix2repl = "ando"
		case "ár":
			suffix2repl = "ar"
		case "ír":
			suffix2repl = "ir"
		}
		word.RemoveLastNRunes(len(suffix1Runes))
		word.ReplaceSuffixRunes(suffix2Runes, []rune(suffix2repl), true)
		return true

	case "ando", "iendo", "ar", "er", "ir":
		word.RemoveLastNRunes(len(suffix1Runes))
		return true

	case "yendo":

		// In the case of "yendo", the "yendo" must lie in RV,
		// and be preceded by a "u" somewhere in the word.

		for i := 0; i < len(word.RS)-(len(suffix1)+len(suffix2)); i++ {

			// Note, the unicode code point for "u" is 117.
			if word.RS[i] == 117 {
				word.RemoveLastNRunes(len(suffix1Runes))
				return true
			}
		}
	}
	return false
}

// Step 1b is the normalization of various "ly" and "ed" sufficies.
//
func step1b(w *snowballword.SnowballWord) bool {

	suffix, suffixRunes := w.FirstSuffix("eedly", "ingly", "edly", "ing", "eed", "ed")

	switch suffix {

	case "":
		// No suffix found
		return false

	case "eed", "eedly":

		// Replace by ee if in R1
		if len(suffixRunes) <= len(w.RS)-w.R1start {
			w.ReplaceSuffixRunes(suffixRunes, []rune("ee"), true)
		}
		return true

	case "ed", "edly", "ing", "ingly":
		hasLowerVowel := false
		for i := 0; i < len(w.RS)-len(suffixRunes); i++ {
			if isLowerVowel(w.RS[i]) {
				hasLowerVowel = true
				break
			}
		}
		if hasLowerVowel {

			// This case requires a two-step transformation and, due
			// to the way we've implemented the `ReplaceSuffix` method
			// here, information about R1 and R2 would be lost between
			// the two.  Therefore, we need to keep track of the
			// original R1 & R2, so that we may set them below, at the
			// end of this case.
			//
			originalR1start := w.R1start
			originalR2start := w.R2start

			// Delete if the preceding word part contains a vowel
			w.RemoveLastNRunes(len(suffixRunes))

			// ...and after the deletion...

			newSuffix, newSuffixRunes := w.FirstSuffix("at", "bl", "iz", "bb", "dd", "ff", "gg", "mm", "nn", "pp", "rr", "tt")
			switch newSuffix {

			case "":

				// If the word is short, add "e"
				if isShortWord(w) {

					// By definition, r1 and r2 are the empty string for
					// short words.
					w.RS = append(w.RS, []rune("e")...)
					w.R1start = len(w.RS)
					w.R2start = len(w.RS)
					return true
				}

			case "at", "bl", "iz":

				// If the word ends "at", "bl" or "iz" add "e"
				w.ReplaceSuffixRunes(newSuffixRunes, []rune(newSuffix+"e"), true)

			case "bb", "dd", "ff", "gg", "mm", "nn", "pp", "rr", "tt":

				// If the word ends with a double remove the last letter.
				// Note that, "double" does not include all possible doubles,
				// just those shown above.
				//
				w.RemoveLastNRunes(1)
			}

			// Because we did a double replacement, we need to fix
			// R1 and R2 manually. This is just becase of how we've
			// implemented the `ReplaceSuffix` method.
			//
			rsLen := len(w.RS)
			if originalR1start < rsLen {
				w.R1start = originalR1start
			} else {
				w.R1start = rsLen
			}
			if originalR2start < rsLen {
				w.R2start = originalR2start
			} else {
				w.R2start = rsLen
			}

			return true
		}

	}

	return false
}