/*
 * Copyright 2009 Yuichiro Moriguchi
 *
 * 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.
 */
package net.morilib.lisp.nano;

/**
 * 
 *
 *
 * @author MORIGUCHI, Yuichiro 2009
 */
public final class LispBoolean extends Atom
implements java.io.Serializable {

	//
	private static final long serialVersionUID = 1583375250021807431L;

	//
	private boolean value;

	/**
	 * 
	 */
	public static final LispBoolean TRUE = new LispBoolean(true);

	/**
	 * 
	 */
	public static final LispBoolean FALSE = new LispBoolean(false);

	/**
	 * 
	 * @param value
	 * @return
	 */
	public static LispBoolean getInstance(boolean value) {
		return value ? TRUE : FALSE;
	}

	//
	private LispBoolean(boolean value) {
		this.value = value;
	}

	/**
	 * 
	 * @param a
	 * @return
	 */
	public boolean isEqv(Atom a) {
		return equals(a);
	}

	/**
	 * 
	 * @return
	 */
	public boolean getValue() {
		return value;
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Atom#print()
	 */
	public String toDisplay() {
		return (value ? "#t" : "#f");
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Atom#getResult()
	 */
	public String toWrite() {
		return (value ? "#t" : "#f");
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Atom#toLispString()
	 */
	public LispString toLispString() {
		return new LispString(value ? "#t" : "#f");
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Datum#isTypeBoolean()
	 */
	public boolean isTypeBoolean() {
		return true;
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Datum#isTrue()
	 */
	public boolean isTrue() {
		return value;
	}

	/* (non-Javadoc)
	 * @see net.morilib.lisp.Atom#toObject()
	 */
	public Object toObject() {
		return Boolean.valueOf(value);
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	public boolean equals(Object o) {
		if(o instanceof LispBoolean) {
			return value == ((LispBoolean)o).value;
		}
		return false;
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		return (value ? 1 : 0);
	}

	/*
	 * (non-Javadoc)
	 * @see net.morilib.lisp.Datum#toString()
	 */
	public String toString() {
		return (value ? "#t" : "#f");
	}

}
