absvariable.java

java实现的P2P多agent中间件

/**
 * ***************************************************************
 * JADE - Java Agent DEvelopment Framework is a framework to develop
 * multi-agent systems in compliance with the FIPA specifications.
 * Copyright (C) 2000 CSELT S.p.A.
 * 
 * GNU Lesser General Public License
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation,
 * version 2.1 of the License.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 * **************************************************************
 */
package jade.content.abs;

import jade.content.schema.*;

/**
 * An abstract descriptor that can hold a variable expression, i.e. an
 * entity that is not known yet.
 * @author Federico Bergenti - Universita` di Parma
 */
public class AbsVariable extends AbsObjectImpl implements AbsTerm {
	private boolean isMeta = false;

	/**
	 * Construct an Abstract descriptor to hold a variable
	 */
	public AbsVariable() {
		super(VariableSchema.BASE_NAME);
	}

	/**
	 * Construct an AbsVariable with the given name and value type 
	 * @param name The name of the variable.
	 * @param valueType The type of values that can be assigned to 
	 * this variable.
	 *
	 */
	public AbsVariable(String name, String valueType) {
		super(VariableSchema.BASE_NAME);

		setName(name);
		setType(valueType);
	}

	/**
	 * Sets the name of this variable.
	 * @param name The new name of this variable.
	 */
	public void setName(String name) {
		set(VariableSchema.NAME, AbsPrimitive.wrap(name));
	} 

	/**
	 * Sets the value type of this variable.
	 * @param valueType The type of values that can be assigned to 
	 * this variable.
	 */
	public void setType(String valueType) {
		set(VariableSchema.VALUE_TYPE, AbsPrimitive.wrap(valueType));
	} 

	/**
	 * Gets the name of this variable.
	 * @return The name of this variable.
	 */
	public String getName() {
		AbsPrimitive abs = (AbsPrimitive) getAbsObject(VariableSchema.NAME);
		if (abs != null) {
			return abs.getString();
		}
		else {
			return null;
		}
	} 

	/**
	 * Gets the value type of this variable.
	 * @return The type of values that can be assigned to 
	 * this variable.
	 */
	public String getType() {
		AbsPrimitive abs = (AbsPrimitive) getAbsObject(VariableSchema.VALUE_TYPE);
		if (abs != null) {
			return abs.getString();
		}
		else {
			return null;
		}
	} 

	/**
	 * Redefine the <code>isGrounded()</code> method in order to 
	 * always return <code>false</code>. 
	 */
	public boolean isGrounded() {
		return false;
	} 

	// Easy way to access the Java class representing AbsVariable.
	// Useful in MIDP where XXX.class is not available
	private static Class absVariableClass = null;
	public static Class getJavaClass() {
		if (absVariableClass == null) {
			try {
				absVariableClass = Class.forName("jade.content.abs.AbsVariable");
			}
			catch (Exception e) {
				// Should never happen
				e.printStackTrace();
			}
		}
		return absVariableClass;
	}

	/** Return true if this object represents a meta term (i.e. symbol ??x) rather than a concrete variable.
	 * This method is currently used only by the semantics framework.
	 * @return true if this object represents a meta term
	 * @since JADE3.4
	 **/
	public final boolean isMetaTerm() {return isMeta;}

	/** Sets the value of isMetaTerm, where the default is false.
	 * This method is currently used only by the semantics framework.
	 * @since JADE3.4
	 **/
	public final void setIsMetaTerm(boolean isMeta) { this.isMeta = isMeta;}

    public int getAbsType() {
    	return ABS_VARIABLE;
    }
}