/*******************************************************************************
* LastCalc - The last calculator you'll ever need
* Copyright (C) 2011, 2012 Uprizer Labs LLC
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Affero General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU Affero General Public License for more
* details.
******************************************************************************/
package com.lastcalc.parsers.math;
import java.io.PrintStream;
import java.io.Serializable;
import java.util.*;
import org.jscience.mathematics.number.FloatingPoint;
import org.jscience.mathematics.number.LargeInteger;
import org.jscience.mathematics.number.Number;
import com.google.common.collect.*;
import com.lastcalc.TokenList;
import com.lastcalc.parsers.Parser;
import com.lastcalc.parsers.Parser.ParseResult;
public class FactorialParser extends Parser {
private static final long serialVersionUID = 2056242056369944551L;
private static TokenList template = TokenList.createD(Lists.<Object> newArrayList("factorial"),LargeInteger.class);
//private static TokenList template=TokenList.createD(LargeInteger.class,Lists.<Object> newArrayList("!"));
@Override
public TokenList getTemplate() {
return template;
}
@SuppressWarnings("rawtypes")
@Override
public ParseResult parse(final TokenList tokens, final int templatePos) {
final String op = (String) tokens.get(templatePos);
final LargeInteger input = (LargeInteger) tokens.get(templatePos + 1);
Number result = null;
if(op.equals("factorial")){
//System.out.println("INput is: "+input);
if(input.isLessThan(LargeInteger.valueOf(20)) && input.isGreaterThan(LargeInteger.ZERO)){
result = LargeInteger.valueOf(factorial(input.longValue()));
return ParseResult.success(tokens.replaceWithTokens(templatePos, templatePos+template.size(), result));
}
}
return ParseResult.fail();
}
protected long factorial(long input){
long fact = 1;
for (long x = input; x > 1; x--){
fact *= x;
}
return fact;
}
@Override
public String toString() {
return "";
}
@Override
public int hashCode() {
return "FactorialParser".hashCode();
}
@Override
public boolean equals(final Object obj) {
return false;
}
}