/** * Title:        ATN<p> * Description:  Implements a simpl ATN parser that uses WordNet data * Copyright:    Copyright (c) by Mark Watson, 2000<p> * @author Mark Watson * @version 1.2 */import java.io.*;import java.util.*;public class ATN {    public ATN() {        try {	    // the following code will read either a local file of a	    // resource in a JAR file:            InputStream ins =		ClassLoader.getSystemResourceAsStream("wncache.dat");            if (ins==null) {                System.out.println("Failed to open 'wncache.dat'");                System.exit(1);            } else {                ObjectInputStream p = new ObjectInputStream(ins);                adj = (Hashtable)p.readObject();                adv = (Hashtable)p.readObject();                noun = (Hashtable)p.readObject();                verb = (Hashtable)p.readObject();                ins.close();            }	    // Augment the WordNet 1.6 entries:	    art = new Hashtable(); addWords(art, ARTS);	    conj = new Hashtable(); addWords(conj, CONJS);	    det = new Hashtable(); addWords(det, DETS);	    pron = new Hashtable(); addWords(pron, PRONS);	    prep = new Hashtable(); addWords(prep, PREPS);	    // fill in a few common verbs that are not in Wordnet 1.6:	    verb.put("ran", b);       } catch (Exception e) {            e.printStackTrace();        }    }    private Boolean b = new Boolean(true);    private void addWords(Hashtable h, String [] ws) {	for (int i=0; i<ws.length; i++) {	    h.put(ws[i], b);	}    }    Hashtable adj, adv, art, conj, det, noun, pron, verb, prep;    String [] PRONS = {"he", "she", "me", "it", "you", "I"};    String [] ARTS  = {"the", "a", "an"};    String [] CONJS = {"and", "or"};    String [] DETS = {"who", "what", "where", "when"};    String [] PREPS = {"on", "at", "under", "above", "behind", "to", "about","down"};    private boolean checkWord(String word, int type) {	if (type == PREP) {	    if (prep.get(word) != null) return true;	} else if (type == VERB) {	    if (verb.get(word) != null) return true;	    // some simple kluges to accept words like "likes" when	    // only "like" is in the lexicon:	    if (word.endsWith("s") || word.endsWith("ed")) {		String s = word.substring(0, word.length() - 1);		if (verb.get(s) != null) return true;	    }	} else if (type == NOUN) {	    if (noun.get(word) != null) return true;	} else if (type == CONJ) {	    if (conj.get(word) != null) return true;	} else if (type == ADJ) {	    if (adj.get(word) != null) return true;	} else if (type == ADV) {	    if (adv.get(word) != null) return true;	} else if (type == PRON) {	    if (pron.get(word) != null) return true;	} else if (type == DET) {	    if (det.get(word) != null) return true;	} else if (type == ART) {	    if (art.get(word) != null) return true;	}	return false;    }    public int [] parse(String s) {        Vector v = new Vector();        StringTokenizer st = new StringTokenizer(s);        while (st.hasMoreTokens()) {            String str = st.nextToken();            if (str.length() > 2 && str.endsWith(",")) {		str = str.substring(0, str.length() - 1);	    }            if (str.length() > 2 && str.endsWith(".")) {		str = str.substring(0, str.length() - 1);	    }            if (str.length() > 2 && str.endsWith(":")) {		str = str.substring(0, str.length() - 1);	    }            if (str.length() > 2 && str.endsWith(";")) {		str = str.substring(0, str.length() - 1);	    }            v.addElement(str.toLowerCase());        }	// It is easier to work with an array, so convert the Vector	// to an array of Java strings:	int size = v.size();	if (size == 0) return null;	words = new String[size];	partsOfSpeech = new int[size];	num_words = size;	for (int i=0; i<size; i++) words[i] = (String)v.elementAt(i);	// quick test against lexicon for word types:	for (int i=0; i<words.length; i++) {	    System.out.print("'" + words[i] + "' possible word types: ");	    if (adj.get(words[i]) != null) System.out.print("adj ");	    if (adv.get(words[i]) != null) System.out.print("adv ");	    if (art.get(words[i]) != null) System.out.print("art ");	    if (noun.get(words[i]) != null) System.out.print("noun ");	    if (prep.get(words[i]) != null) System.out.print("prep ");	    if (verb.get(words[i]) != null) System.out.print("verb ");	    System.out.println();	}	System.out.println();	// execute the parsing helper methods until one succeeds:	parse_it();	return null;    }    String [] words;    int [] partsOfSpeech;    int wordIndex;    int num_words;        public static void main(String [] args) {	ATN nf = new ATN();	if (args.length < 1) {	    nf.parse("the dog ran down the street");	} else {	    for (int i=0; i<args.length; i++) {		System.out.println("\nProcessing : " + args[i]);		nf.parse(args[i]);	    }	}    }    //////////////// ATN functions:    String getPOSname(int pos) {	switch (pos) {	case 1: return "NP";	case 2: return "VP";	case 3: return "PP";	case 1001: return "noun";	case 1002: return "verb";	case 1003: return "prep";	case 1004: return "conj";	case 1005: return "adj";	case 1006: return "adv";	case 1007: return "pron";	case 1008: return "det";	case 1009: return "art";	default: return "unknown";	}    }    public final static int NP = 1;    public final static int VP = 2;    public final static int PP = 3;    public final static int NOUN = 1001;    public final static int VERB = 1002;    public final static int PREP = 1003;    public final static int CONJ = 1004;    public final static int ADJ  = 1005;    public final static int ADV  = 1006;    public final static int PRON = 1007;    public final static int DET  = 1008;    public final static int ART  = 1009;    public final static int NUM_S = 9;    //    int [] LEN_S   = { 5,  4,  3,  4,  3,  2,  2,  2,  1};    int [] ALL_S [] = {	{NP, VP, NP, PP, VP},	{NP, VP, PP, NP},	{NP, VP, NP},	{VP, NP, PP, NP},	{VP, PP, NP},	{NP, VP},	{VP, PP},	{VP, NP},	{VP}    };    //////////////// The actual parser:    int parsePP(int start_word_index, int word_index) {	if (word_index >= num_words)  return word_index;	// test ATN transitions <PREP> --> <NP>	if (checkWord(words[word_index], PREP)) {	    partsOfSpeech[start_word_index + word_index] = PREP;	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		return ii;	    }	}	return -1;    }    int parseNP(int start_word_index, int word_index) {	if (word_index >= num_words)  return word_index;	// test ATN transitions <NOUN> --> <CONJ> --> <NP>	if (word_index < num_words - 2 && checkWord(words[word_index], NOUN)) {	    if (checkWord(words[word_index + 1], CONJ)) {		int ii = parseNP(start_word_index, word_index + 2);		if (ii > -1) {		    partsOfSpeech[start_word_index + word_index] = NOUN;		    partsOfSpeech[start_word_index + word_index + 1] = CONJ;		    return ii;		}	    }	}	// test ATN transitions <ART> --> <NP>	if (word_index < num_words - 1 && checkWord(words[word_index], ART)) {	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		partsOfSpeech[start_word_index + word_index] = ART;		return ii;	    }	}	// test ATN transitions <DET> --> <NP>	if (word_index < num_words - 1 && checkWord(words[word_index], ADJ)) {	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		partsOfSpeech[start_word_index + word_index] = ADJ;		return ii;	    }	}	// test ATN transitions <ADJ> --> <NP>	if (checkWord(words[word_index], ADJ)) {	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		partsOfSpeech[start_word_index + word_index] = ADJ;		return ii;	    }	}	// test ATN transitions <ADV> --> <NP>	if (word_index < num_words - 1 && checkWord(words[word_index], ADV)) {	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		partsOfSpeech[start_word_index + word_index] = ADV;		return ii;	    }	}	// test ATN transitions <NOUN> --> <NOUN>	if (word_index < num_words - 1 && checkWord(words[word_index], NOUN)) {	    if (checkWord(words[word_index + 1], NOUN)) {		partsOfSpeech[start_word_index + word_index] = NOUN;		partsOfSpeech[start_word_index + word_index + 1] = NOUN;		return word_index + 2;	    }	}	if (checkWord(words[word_index], NOUN)) {	    partsOfSpeech[start_word_index + word_index] = NOUN;	    return word_index + 1;	}	if (checkWord(words[word_index], PRON)) {	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		partsOfSpeech[start_word_index + word_index] = PRON;		return ii;	    }	}	if (checkWord(words[word_index], PRON)) {	    partsOfSpeech[start_word_index + word_index] = PRON;	    return word_index + 1;	}	return -1;    }    int parseVP(int start_word_index, int word_index) {	if (word_index >= num_words)  return word_index;	// test ATN transitions <V> --> <NP> --> <PP>	if (checkWord(words[word_index], VERB)) {	    partsOfSpeech[start_word_index + word_index] = VERB;	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		int jj = parsePP(start_word_index, ii);		if (jj > -1) {		    return jj;		}	    }	}	// test ATN transitions <V> --> <NP>	if (checkWord(words[word_index], VERB)) {	    partsOfSpeech[start_word_index + word_index] = VERB;	    int ii = parseNP(start_word_index, word_index + 1);	    if (ii > -1) {		return ii;	    }	}	// test ATN transitions <V> --> <PP>	if (checkWord(words[word_index], VERB)) {	    partsOfSpeech[start_word_index + word_index] = VERB;	    int ii = parsePP(start_word_index, word_index + 1);	    if (ii > -1) {		return ii;	    }	}	if (checkWord(words[word_index], VERB)) {	    partsOfSpeech[start_word_index + word_index] = VERB;	    return word_index + 1;	}	return -1;    }    int parseHelper(int [] atn, int start_word_index) {	int word_index = 0;	int len_atn = atn.length;	int last_word_index = word_index;	for (int i=0; i<len_atn; i++) {	    last_word_index = word_index;	    switch (atn[i]) {	    case NP: word_index = parseNP(start_word_index, word_index);  break;	    case VP: word_index = parseVP(start_word_index, word_index);  break;	    case PP: word_index = parsePP(start_word_index, word_index);  break;	    }	    if (word_index == -1)  return last_word_index;	}	return word_index;    }    int parseSentence(int start_word_index) {	int max_val = -1;	int max_word_index = 0;	for (int i=0; i<NUM_S; i++) {	    int k = parseHelper(ALL_S[i], start_word_index);	    //System.out.println("Score for ATN " + i + " is " + k);	    if (k > max_val) {		max_val = k;		max_word_index = i;	    }	}	System.out.println("Best ATN at word_index " + max_word_index);	parseHelper(ALL_S[max_word_index], start_word_index);	for (int i=0; i<num_words; i++) {	    if (partsOfSpeech[start_word_index + i] == 0) {		if (checkWord(words[i], NOUN)) {		    partsOfSpeech[start_word_index + i] = NOUN;		}		if (checkWord(words[i], CONJ)) {		    partsOfSpeech[start_word_index + i] = CONJ;		}	    }	}	return max_val;    }    void parse_it() {	int word_index = parseSentence(0);	//System.out.println("word_index from S ATN = " + word_index);	for (int i=0; i<num_words; i++) {	    System.out.println(" word: " + words[i] + 			       " part of speech: " + getPOSname(partsOfSpeech[i]));	}    }}