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-package tweetlda;
-
-
-/*
-
- Porter stemmer in Java. The original paper is in
-
- Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
- no. 3, pp 130-137,
-
- See also http://www.tartarus.org/~martin/PorterStemmer
-
- History:
-
- Release 1
-
- Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
- The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
- is then out outside the bounds of b.
-
- Release 2
-
- Similarly,
-
- Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
- 'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
- b[j] is then outside the bounds of b.
-
- Release 3
-
- Considerably revised 4/9/00 in the light of many helpful suggestions
- from Brian Goetz of Quiotix Corporation (brian@quiotix.com).
-
- Release 4
-
-*/
-
-import java.io.*;
-
-/**
- * Stemmer, implementing the Porter Stemming Algorithm
- *
- * The Stemmer class transforms a word into its root form. The input
- * word can be provided a character at time (by calling add()), or at once
- * by calling one of the various stem(something) methods.
- */
-
-class Stemmer
-{ private char[] b;
- private int i, /* offset into b */
- i_end, /* offset to end of stemmed word */
- j, k;
- private static final int INC = 50;
- /* unit of size whereby b is increased */
- public Stemmer()
- { b = new char[INC];
- i = 0;
- i_end = 0;
- }
-
- /**
- * Add a character to the word being stemmed. When you are finished
- * adding characters, you can call stem(void) to stem the word.
- */
-
- public void add(char ch)
- { if (i == b.length)
- { char[] new_b = new char[i+INC];
- for (int c = 0; c < i; c++) new_b[c] = b[c];
- b = new_b;
- }
- b[i++] = ch;
- }
-
-
- /** Adds wLen characters to the word being stemmed contained in a portion
- * of a char[] array. This is like repeated calls of add(char ch), but
- * faster.
- */
-
- public void add(char[] w, int wLen)
- { if (i+wLen >= b.length)
- { char[] new_b = new char[i+wLen+INC];
- for (int c = 0; c < i; c++) new_b[c] = b[c];
- b = new_b;
- }
- for (int c = 0; c < wLen; c++) b[i++] = w[c];
- }
-
- /**
- * After a word has been stemmed, it can be retrieved by toString(),
- * or a reference to the internal buffer can be retrieved by getResultBuffer
- * and getResultLength (which is generally more efficient.)
- */
- public String toString() { return new String(b,0,i_end); }
-
- /**
- * Returns the length of the word resulting from the stemming process.
- */
- public int getResultLength() { return i_end; }
-
- /**
- * Returns a reference to a character buffer containing the results of
- * the stemming process. You also need to consult getResultLength()
- * to determine the length of the result.
- */
- public char[] getResultBuffer() { return b; }
-
- /* cons(i) is true <=> b[i] is a consonant. */
-
- private final boolean cons(int i)
- { switch (b[i])
- { case 'a': case 'e': case 'i': case 'o': case 'u': return false;
- case 'y': return (i==0) ? true : !cons(i-1);
- default: return true;
- }
- }
-
- /* m() measures the number of consonant sequences between 0 and j. if c is
- a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
- presence,
-
- <c><v> gives 0
- <c>vc<v> gives 1
- <c>vcvc<v> gives 2
- <c>vcvcvc<v> gives 3
- ....
- */
-
- private final int m()
- { int n = 0;
- int i = 0;
- while(true)
- { if (i > j) return n;
- if (! cons(i)) break; i++;
- }
- i++;
- while(true)
- { while(true)
- { if (i > j) return n;
- if (cons(i)) break;
- i++;
- }
- i++;
- n++;
- while(true)
- { if (i > j) return n;
- if (! cons(i)) break;
- i++;
- }
- i++;
- }
- }
-
- /* vowelinstem() is true <=> 0,...j contains a vowel */
-
- private final boolean vowelinstem()
- { int i; for (i = 0; i <= j; i++) if (! cons(i)) return true;
- return false;
- }
-
- /* doublec(j) is true <=> j,(j-1) contain a double consonant. */
-
- private final boolean doublec(int j)
- { if (j < 1) return false;
- if (b[j] != b[j-1]) return false;
- return cons(j);
- }
-
- /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
- and also if the second c is not w,x or y. this is used when trying to
- restore an e at the end of a short word. e.g.
-
- cav(e), lov(e), hop(e), crim(e), but
- snow, box, tray.
-
- */
-
- private final boolean cvc(int i)
- { if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) return false;
- { int ch = b[i];
- if (ch == 'w' || ch == 'x' || ch == 'y') return false;
- }
- return true;
- }
-
- private final boolean ends(String s)
- { int l = s.length();
- int o = k-l+1;
- if (o < 0) return false;
- for (int i = 0; i < l; i++) if (b[o+i] != s.charAt(i)) return false;
- j = k-l;
- return true;
- }
-
- /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
- k. */
-
- private final void setto(String s)
- { int l = s.length();
- int o = j+1;
- for (int i = 0; i < l; i++) b[o+i] = s.charAt(i);
- k = j+l;
- }
-
- /* r(s) is used further down. */
-
- private final void r(String s) { if (m() > 0) setto(s); }
-
- /* step1() gets rid of plurals and -ed or -ing. e.g.
-
- caresses -> caress
- ponies -> poni
- ties -> ti
- caress -> caress
- cats -> cat
-
- feed -> feed
- agreed -> agree
- disabled -> disable
-
- matting -> mat
- mating -> mate
- meeting -> meet
- milling -> mill
- messing -> mess
-
- meetings -> meet
-
- */
-
- private final void step1()
- { if (b[k] == 's')
- { if (ends("sses")) k -= 2; else
- if (ends("ies")) setto("i"); else
- if (b[k-1] != 's') k--;
- }
- if (ends("eed")) { if (m() > 0) k--; } else
- if ((ends("ed") || ends("ing")) && vowelinstem())
- { k = j;
- if (ends("at")) setto("ate"); else
- if (ends("bl")) setto("ble"); else
- if (ends("iz")) setto("ize"); else
- if (doublec(k))
- { k--;
- { int ch = b[k];
- if (ch == 'l' || ch == 's' || ch == 'z') k++;
- }
- }
- else if (m() == 1 && cvc(k)) setto("e");
- }
- }
-
- /* step2() turns terminal y to i when there is another vowel in the stem. */
-
- private final void step2() { if (ends("y") && vowelinstem()) b[k] = 'i'; }
-
- /* step3() maps double suffices to single ones. so -ization ( = -ize plus
- -ation) maps to -ize etc. note that the string before the suffix must give
- m() > 0. */
-
- private final void step3() { if (k == 0) return; /* For Bug 1 */ switch (b[k-1])
- {
- case 'a': if (ends("ational")) { r("ate"); break; }
- if (ends("tional")) { r("tion"); break; }
- break;
- case 'c': if (ends("enci")) { r("ence"); break; }
- if (ends("anci")) { r("ance"); break; }
- break;
- case 'e': if (ends("izer")) { r("ize"); break; }
- break;
- case 'l': if (ends("bli")) { r("ble"); break; }
- if (ends("alli")) { r("al"); break; }
- if (ends("entli")) { r("ent"); break; }
- if (ends("eli")) { r("e"); break; }
- if (ends("ousli")) { r("ous"); break; }
- break;
- case 'o': if (ends("ization")) { r("ize"); break; }
- if (ends("ation")) { r("ate"); break; }
- if (ends("ator")) { r("ate"); break; }
- break;
- case 's': if (ends("alism")) { r("al"); break; }
- if (ends("iveness")) { r("ive"); break; }
- if (ends("fulness")) { r("ful"); break; }
- if (ends("ousness")) { r("ous"); break; }
- break;
- case 't': if (ends("aliti")) { r("al"); break; }
- if (ends("iviti")) { r("ive"); break; }
- if (ends("biliti")) { r("ble"); break; }
- break;
- case 'g': if (ends("logi")) { r("log"); break; }
- } }
-
- /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
-
- private final void step4() { switch (b[k])
- {
- case 'e': if (ends("icate")) { r("ic"); break; }
- if (ends("ative")) { r(""); break; }
- if (ends("alize")) { r("al"); break; }
- break;
- case 'i': if (ends("iciti")) { r("ic"); break; }
- break;
- case 'l': if (ends("ical")) { r("ic"); break; }
- if (ends("ful")) { r(""); break; }
- break;
- case 's': if (ends("ness")) { r(""); break; }
- break;
- } }
-
- /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
-
- private final void step5()
- { if (k == 0) return; /* for Bug 1 */ switch (b[k-1])
- { case 'a': if (ends("al")) break; return;
- case 'c': if (ends("ance")) break;
- if (ends("ence")) break; return;
- case 'e': if (ends("er")) break; return;
- case 'i': if (ends("ic")) break; return;
- case 'l': if (ends("able")) break;
- if (ends("ible")) break; return;
- case 'n': if (ends("ant")) break;
- if (ends("ement")) break;
- if (ends("ment")) break;
- /* element etc. not stripped before the m */
- if (ends("ent")) break; return;
- case 'o': if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
- /* j >= 0 fixes Bug 2 */
- if (ends("ou")) break; return;
- /* takes care of -ous */
- case 's': if (ends("ism")) break; return;
- case 't': if (ends("ate")) break;
- if (ends("iti")) break; return;
- case 'u': if (ends("ous")) break; return;
- case 'v': if (ends("ive")) break; return;
- case 'z': if (ends("ize")) break; return;
- default: return;
- }
- if (m() > 1) k = j;
- }
-
- /* step6() removes a final -e if m() > 1. */
-
- private final void step6()
- { j = k;
- if (b[k] == 'e')
- { int a = m();
- if (a > 1 || a == 1 && !cvc(k-1)) k--;
- }
- if (b[k] == 'l' && doublec(k) && m() > 1) k--;
- }
-
- /** Stem the word placed into the Stemmer buffer through calls to add().
- * Returns true if the stemming process resulted in a word different
- * from the input. You can retrieve the result with
- * getResultLength()/getResultBuffer() or toString().
- */
- public void stem()
- { k = i - 1;
- if (k > 1) { step1(); step2(); step3(); step4(); step5(); step6(); }
- i_end = k+1; i = 0;
- }
-
- /** Test program for demonstrating the Stemmer. It reads text from a
- * a list of files, stems each word, and writes the result to standard
- * output. Note that the word stemmed is expected to be in lower case:
- * forcing lower case must be done outside the Stemmer class.
- * Usage: Stemmer file-name file-name ...
- */
- public static void main(String[] args)
- {
- char[] w = new char[501];
- Stemmer s = new Stemmer();
- for (int i = 0; i < args.length; i++)
- try
- {
- FileInputStream in = new FileInputStream(args[i]);
-
- try
- { while(true)
-
- { int ch = in.read();
- if (Character.isLetter((char) ch))
- {
- int j = 0;
- while(true)
- { ch = Character.toLowerCase((char) ch);
- w[j] = (char) ch;
- if (j < 500) j++;
- ch = in.read();
- if (!Character.isLetter((char) ch))
- {
- /* to test add(char ch) */
- for (int c = 0; c < j; c++) s.add(w[c]);
-
- /* or, to test add(char[] w, int j) */
- /* s.add(w, j); */
-
- s.stem();
- { String u;
-
- /* and now, to test toString() : */
- u = s.toString();
-
- /* to test getResultBuffer(), getResultLength() : */
- /* u = new String(s.getResultBuffer(), 0, s.getResultLength()); */
-
- System.out.print(u);
- }
- break;
- }
- }
- }
- if (ch < 0) break;
- System.out.print((char)ch);
- }
- }
- catch (IOException e)
- { System.out.println("error reading " + args[i]);
- break;
- }
- }
- catch (FileNotFoundException e)
- { System.out.println("file " + args[i] + " not found");
- break;
- }
- }
-}
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