operator_proximity.java

java实现的全文搜索引擎

/**
 * 
 */
package cn.edu.nju.software.ruse;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author spring
 *
 */
public class Operator_Proximity extends Operator {

	/* (non-Javadoc)
	 * @see cn.edu.nju.software.ruse.Operator#getPRI()
	 */
	public Operator_Proximity() {
		desription = "PROXIMITY";
		PRI = PRI_PROXIMITY;
	}
	public int getPRI() {
		return PRI;
	}
	public HashSet<File> getFileSet(String expre, Index index) {
		//System.err.println("@Operator_Proximity Starting to getFileSet from the index!");
		expre = expre.trim();
		expre = expre.toLowerCase();
		HashMap<String, HashMap<File,HashSet<Integer>>> fileContentsIndex = index.getFileContentsIndex();
		List<String> word = new ArrayList<String>();
		HashSet<File> result = new HashSet<File>();
		HashSet<File> resultProcessed = new HashSet<File>();
		
		Pattern p = Pattern.compile("\\b\\w+\\b");
		Matcher m = p.matcher(expre);
		int j = -1;
		while(m.find()) {
			j++;
			word.add(j, m.group());
		}
		
		int distance;
		String s = word.get(word.size() - 1);
		if(Character.isDigit(s.charAt(0))) {
			distance = Integer.parseInt(s);
			word.remove(word.size() - 1);
		} else {
			distance = 0;
		}
		
		/**
		 * do AND operation for all the words, and get the result Set.
		 * */
		result.addAll(fileContentsIndex.get(word.get(0)).keySet());
		for(int i = 1;i < word.size();i++) {
			s = word.get(i);
			result.retainAll(fileContentsIndex.get(s).keySet());
		}
		
		/**
		 * calculate the distance from the result files, which do it from word[0]
		 * */
		Iterator<File> it = result.iterator();
		while(it.hasNext()) {
			resultProcessed.add(it.next());
		}
		HashMap<File,HashSet<Integer>> hm;
		HashSet<Integer> ts;
		String w;
		HashMap<Integer,String> pos = new HashMap<Integer,String>();
		int maxPos = 0;
		
		String test = new String();
		String regex = new String();
		for(int i = 0;i < word.size();i++) {
			if(i == word.size() - 1) {
				regex += "(" + word.get(i) + ")";
				
			} else {
				regex += "(" + word.get(i) + ")" + "@{0," + distance + "}"; 
			}
		}
		Pattern p_test = Pattern.compile(regex);
		Matcher m_test;
		it = result.iterator();
		while(it.hasNext()) {
			File f = it.next();
			pos.clear();
			test = "";
			for(int i = 0;i < word.size();i++) {
				w = word.get(i);
				hm = fileContentsIndex.get(w);
				ts = hm.get(f);
				Iterator<Integer> itTS = ts.iterator();
				while(itTS.hasNext()) {
					Integer position = itTS.next();
					if(position.intValue() > maxPos) {
						maxPos = position.intValue();
					}
					pos.put(position.intValue(), w);
				}
			}
			int k = 0;
			String temps;
			while(k <= maxPos) {
				temps = pos.get(k);
				if(temps == null) {
					test += "@";
				} else {
					test += temps;
				}
				k++;
			}
			m_test = p_test.matcher(test);
			if(!m_test.find()) {
				resultProcessed.remove(f);
			}
		}
		return resultProcessed;
	}

}