Golang SnowballWord.R2start方法代码示例

func preprocess(word *snowballword.SnowballWord) {

	r1start, r2start, rvstart := findRegions(word)
	word.R1start = r1start
	word.R2start = r2start
	word.RVstart = rvstart

}

// Trim off leading apostropes.  (Slight variation from
// NLTK implementation here, in which only the first is removed.)
//
func trimLeftApostrophes(word *snowballword.SnowballWord) {
	var (
		numApostrophes int
		r              rune
	)

	for numApostrophes, r = range word.RS {

		// Check for "'", which is unicode code point 39
		if r != 39 {
			break
		}
	}
	if numApostrophes > 0 {
		word.RS = word.RS[numApostrophes:]
		word.R1start = word.R1start - numApostrophes
		word.R2start = word.R2start - numApostrophes
	}
}

// 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
}