using GLib; /** * Port to Vala of the Csharp version of of the Porter stemmer. * * (The original Csharp version was written by: André Hazelwood, Sep 2001). * * Serge Hulne */ class Stemmer { private char[] b; private int i; /* offset into b */ private int i_end; /* offset to end of stemmed word */ private int j; private int k; private static 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 add2(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() { var s = (string) b; return s.slice(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 bool cons(int i) { switch (b[i]) { case 'a': return false; case 'e': return false; case 'i': return false; case 'o': return false; 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, gives 0 vc gives 1 vcvc gives 2 vcvcvc gives 3 .... */ private 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 bool 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 bool 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 bool 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 bool ends(string s) { int l = s.length; int o = k-l+1; if (o < 0) return false; char[] sc = (char[]) s.data; for (int i = 0; i < l; i++) if (b[o+i] != sc[i]) return false; j = k-l; return true; } /* setto(s) sets (j+1),...k to the characters in the string s, readjusting k. */ private void setto(string s) { int l = s.length; int o = j+1; char[] sc = (char[]) s.data; for (int i = 0; i < l; i++) b[o+i] = sc[i]; k = j+l; } /* r(s) is used further down. */ private 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 void step1() { //print("->step1()\n"); 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 void step2() { //print("->step2()\n"); 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 void step3() { //print("->step3()\n"); 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; } break; default : break; } } /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */ private void step4() { //print("->step4()\n"); 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 vcvc. */ private void step5() { //print("->step5()\n"); 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 void step6() { //print("->step6()\n"); 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 words, 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 list of words ... */ int main(string[] args) { var s = new Stemmer(); var i = 0; if (args.length>1) { for (i=0; i