Utils.java

/*
   Copyright 2010-2012 by Bits and Pixels, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/
/**
 * Utils primarily consists of some edit distance functions.
 */

package com.jaivox.interpreter;

import java.util.*;
import java.awt.Point;

import com.jaivox.util.Log;

public class Utils {

	static String terms = " \t\r\n!@$#$%^&*()_-~`+={}[]|\\:;\"\'<>,.?/";

	public Utils () {
	}


	String [] splitTokens (String line) {
		StringTokenizer st = new StringTokenizer (line, terms);
		int n = st.countTokens ();
		String qq [] = new String [n];
		for (int i=0; i<n; i++) {
			qq [i] = st.nextToken ();
		}
		return qq;
	}

	String makeString (String tokens []) {
		StringBuffer sb = new StringBuffer ();
		int n = tokens.length;
		if (n == 0) return "";
		sb.append (tokens [0]);
		for (int i=1; i<n; i++) {
			sb.append (" "+tokens [i]);
		}
		String result = new String (sb);
		return result;
	}

	// http://en.wikibooks.org/wiki/Algorithm_implementation/Strings/Levenshtein_distance#Java
	int minimum(int a, int b, int c) {
		return Math.min (Math.min(a, b), c);
	}

	int editDistance (String one, String two) {
		int n = one.length ();
		int m = two.length ();
		int [][] distance = new int [n + 1][m + 1];

		for (int i = 0; i <= n; i++)
			distance [i][0] = i;
		for (int j = 0; j <= m; j++)
			distance [0][j] = j;

		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= m; j++) {
				distance [i][j] = minimum (
				distance [i - 1][j] + 1,
				distance [i][j - 1] + 1,
				distance [i - 1][j - 1]
					+ ((one.charAt (i - 1) == two.charAt (j - 1)) ? 0 : 1));
			}
		}

		return distance [n][m];
	}

	int approxMatch (String a, String b) {
		String one [] = a.split (" ");
		String two [] = b.split (" ");
		int d = approxMatch (one, two);
		return d;
	}

    int approxMatch (String one [], String two []) {
		int n = one.length;
		int m = two.length;
        int [][] distance = new int [n + 1][m + 1];

        for (int i = 0; i <= n; i++) {
            distance [i][0] = i;
        }
        for (int j = 0; j <= m; j++) {
            distance [0][j] = j;
        }
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                distance[i][j] = minimum (
                    distance[i-1][j] + 1,
                    distance[i][j-1] + 1,
                    distance[i-1][j-1] + (one[i-1].equals (two[j-1]) ? 0 : 1));
            }
        }
        return distance [n][m];
    }

    static void quicksortpointy (Point p[], int low, int high) {
        int lo = low;
        int hi = high;
        if (lo >= hi) {
            return;
        }
        int mid = p[(lo + hi) / 2].y;
        while (lo <= hi) {
            while (lo < high && p[lo].y < mid) {
                lo++;
            }
            while (hi > low && p[hi].y > mid) {
                hi--;
            }
            if (lo <= hi) {
                Point t;
                t = p[lo];
                p[lo] = p[hi];
                p[hi] = t;
                lo++;
                hi--;
            }
        }

        if (low < hi) {
            quicksortpointy (p, low, hi);
        }
        if (lo < high) {
            quicksortpointy (p, lo, high);
        }
    }
};