/*
 *  JFLAP - Formal Languages and Automata Package
 * 
 * 
 *  Susan H. Rodger
 *  Computer Science Department
 *  Duke University
 *  August 27, 2009

 *  Copyright (c) 2002-2009
 *  All rights reserved.

 *  JFLAP is open source software. Please see the LICENSE for terms.
 *
 */





package pumping.cf;

import pumping.*;

/**
 * The context-free pumping lemma for <i>L</i> =
 * {<i>a<sup>n</sup>b<sup>j</sup>a<sup>n</sup>b<sup>j</sup></i> : <i>n</i> 
 * &#8805; 0, <i>j</i> &#8805; 0}.
 * 
 * @author Jinghui Lim & Chris Morgan
 *
 */
public class AnBjAnBj extends ContextFreePumpingLemma 
{
    public String getTitle() 
    {
        return "a^n b^j a^n b^j : n >= 0, j >= 0";
    }

    public String getHTMLTitle() 
    {
        return "<i>a<sup>n</sup>b<sup>j</sup>a<sup>n</sup>b<sup>j</sup></i> : <i>n</i> " +
            GREATER_OR_EQ + " 0, <i>j</i> " + GREATER_OR_EQ + " 0";
    }
    
    public void setDescription()
    {
    	partitionIsValid = false;
    	explanation = "For any <i>m</i> value, a possible value for <i>w</i> is \"a<sup><i>m</i></sup>" +
    			"b<sup><i>m</i></sup>a<sup><i>m</i></sup>b<sup><i>m</i></sup>\".  To be in the language with " +
    			"this example, <i>v</i> & <i>y</i> together cannot possess identical letters that are from separate " +
    			"blocks of alike letters (ex: <i>v</i> has \"b\"s from the first set of \"b\"s, " +
    			"while <i>y</i> has \"b\"s from the second set of \"b\"s).  Because of this, any increase or decrease " +
    			"in \"a\"s or \"b\"s will not be matched by any change in the other blocks of similar letters, " +
    			"resulting in an inequality that prevents the decomposition from working.  Thus, this language is " +
    			"not context-free.";
    }

    protected void chooseW() 
    {
        w = pumpString("a", getM()) + pumpString("b", getM()) + 
            pumpString("a", getM()) + pumpString("b", getM());
    }
    
    public void chooseDecomposition() {
    	int step = w.length() / 2 - 1;
    	if (step > m - 2)
    		step = m - 2;
    	if (w.indexOf('a') > -1)
    		setDecomposition(new int[]{0, 1, step, 1});
    	else
    		setDecomposition(new int[]{w.indexOf('b'), 1, step, 1});
    		
    }

    public void chooseI() 
    {
        i = 0;
    }
    
    protected void setRange()
    {
        myRange = new int[]{3, 5};
    }

    protected void addCases() 
    {
        /*
         * v is string of a's and y is string of a's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") > -1 && v.indexOf("b") == -1 &&
                        y.indexOf("a") > -1 && y.indexOf("b") == -1)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"a\"s and y is a string of \"a\"s";
                }
                
                public int[] getPreset()
                {
                    return new int[]{0, 1, 0, 1};                    
                }
            });
        /*
         * v is string of a's and y is string of a's followed by b's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") > -1 && v.indexOf("b") == -1 &&
                        y.indexOf("a") > -1 && y.indexOf("b") > -1 && 
                        y.indexOf("a") < y.indexOf("b"))
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"a\"s and y is a string of \"a\"s followed by \"b\"s";
                }
                
                public int[] getPreset()
                {
                    return new int[]{1, 1, 0, m-1};
                }
            });
        /*
         * v is string of a's and y is string of b's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") > -1 && v.indexOf("b") == -1 && 
                        y.indexOf("a") == -1 && y.indexOf("b") > -1)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"a\"s and y is a string of \"b\"s";
                }
                
                public int[] getPreset()
                {
                    return new int[]{m - 1, 1, 0, 1};
                }
            });
        /*
         * v is string of a's followed by b's and y is string of b's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") > -1 && v.indexOf("b") > -1 &&
                        v.indexOf("a") < v.indexOf("b") &&
                        y.indexOf("a") == -1 && y.indexOf("b") > -1)
                        
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"a\"s followed by \"b\"s and y is a string of \"b\"s";
                }
                
                public int[] getPreset()
                {
                    return new int[]{m - 1, 2, 0, 1};
                }
            });
        /*
         * v is a string of b's and y is a string of b's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") == -1 && v.indexOf("b") > -1 &&
                        y.indexOf("a") == -1 && y.indexOf("b") > -1)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"b\"s and y is a string of \"b\"s";
                }
                
                public int[] getPreset()
                {
                    return new int[]{m, 1, 0, 1};
                }
            });   
        /*
         * v is a string of b's and y is a string of b's followed by a's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") == -1 && v.indexOf("b") > -1 &&
                        y.indexOf("a") > -1 && y.indexOf("b") > -1 && 
                        y.indexOf("a") > y.indexOf("b"))
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"b\"s and y is a string of \"b\"s followed by \"a\"s";
                }

                public int[] getPreset()
                {
                    return new int[]{2 * m - 2, 1, 0, 2};
                }
            });
        /*
         * v is a string of b's and y is a string of a's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") == -1 && v.indexOf("b") > -1 &&
                        y.indexOf("a") > -1 && y.indexOf("b") == -1)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"b\"s and y is a string of \"a\"s";
                }

                public int[] getPreset()
                {
                    return new int[]{2 * m - 1, 1, 0, 1};
                }
            });
        /*
         * v is a string of b'a followed by a's and y is a string of a's
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.indexOf("a") > -1 && v.indexOf("b") > -1 && 
                        v.indexOf("a") > v.indexOf("b") &&
                        y.indexOf("a") > -1 && y.indexOf("b") > -1 )
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a string of \"b\"s followed by \"a\"s and y is a string of \"a\"s";
                }
                        
                public int[] getPreset()
                {
                    return new int[]{2 * m - 1, 2, 0, 1};
                }
            });        
        /*
         * v is an empty string and y is a non-empty string
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.length() == 0 && y.length() > 0)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is an empty string and y is a non-empty string";
                }
                
                public int[] getPreset()
                {
                    return new int[]{2 * m, 0, 1, 1};
                }
            });
        /*
         * v is a non-empty string and y is an empty string
         */
        myAllCases.add(new Case()
            {
                public boolean isCase(String v, String y) 
                {
                    if(v.length() > 0 && y.length() == 0)
                        return true;
                    return false;
                }

                public String description() 
                {
                    return "v is a non-empty string and y is an empty string";
                }
                
                public int[] getPreset()
                {
                    return new int[]{2 * m, 1, 0, 0};
                }
            });
    }
    
    public boolean isInLang(String s)
    {
    	String first, last; 
    	int halfSize = s.length() / 2;
    	first = s.substring(0, halfSize);
    	last = s.substring(halfSize);
    	if (!first.equals(last))
    		return false;    	    
    	
    	char[] list = new char[]{'a','b'};
    	if (LemmaMath.isMixture(first, list) || LemmaMath.isMixture(last, list))    	
    		return false;
    	
    	return true;
    }
}