/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * JavaWorld Library, Copyright 2011 Bryan Chadwick * * * * FILE: ./universe/Cons.java * * * * This file is part of JavaWorld. * * * * JavaWorld is free software: you can redistribute it and/or * * modify it under the terms of the GNU General Public License * * as published by the Free Software Foundation, either version * * 3 of the License, or (at your option) any later version. * * * * JavaWorld 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 General Public License for more details. * * * * You should have received a copy of the GNU General Public License * * along with JavaWorld. If not, see . * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ package universe; /** Represents a Lisp style cons list. You should not use the constructor, use List.push(...) * to add an element to the front of the list. It is left public so that the parser * generator can parse different lists if needed. */ public class Cons extends List{ private static final long serialVersionUID = 1; protected final X first; protected final List rest; //private final int hash; public Cons(X f, List r){ super(r.length()+1); this.first = f; this.rest = r; //hash = first.hashCode()+3*rest.hashCode(); } public X top(){ return this.first; } public List pop(){ return this.rest; } public boolean isEmpty(){ return false; } public boolean equals(Object o){ if(! (o instanceof Cons))return false; List c = (List)o; if(c.length() != length())return false; for(X x:this){ if(!x.equals(c.top()))return false; c = c.pop(); } return true; } public int hashCode(){ //return hash; return this.first.hashCode()+3*this.rest.hashCode(); } /** Getter for Entry.key */ public X getFirst(){ return this.first; } /** Getter for Entry.val */ public List getRest(){ return this.rest; } }