jadex.rules.parser.conditions.javagrammar.ExistentialDeclaration Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jadex-rules Show documentation

Jadex Rules is a small lightweight rule engine, which currently employs the well-known Rete algorithm for highly efficient rule matching. Jadex rules is therefore similar to other rule engines like JESS and Drools. Despite the similarities there are also important differences between these systems: * Jadex Rules is very small and intended to be used as component of other software. Even though rules can be specified in a Java dialect as well as (a small variation of) the CLIPS language its primary usage is on the API level. Jadex Rules is currently the core component of the Jadex BDI reasoning engine. * Jadex Rules cleanly separates between state and rule representation. This allows the state implementation as well as the matcher to be flexibly exchanged. Some experiments have e.g. been conducted with a Jena representation. Regarding the matcher, it is planned to support also the Treat algorithm, which has a lower memory footprint than Rete. * Jadex Rules pays close attention to rule debugging. The state as well as the rete engine can be observed at runtime. The rule debugger provides functionalities to execute a rule program stepwise and also use rule breakpoints to stop the execution at those points.

There is a newer version: 2.4

Show newest version

package jadex.rules.parser.conditions.javagrammar;

import jadex.rules.rulesystem.rules.Variable;
import jadex.rules.state.OAVObjectType;


/**
 *  Demand the existence of an object and bind an instance to a variable.
 */
public class ExistentialDeclaration	extends	Expression
{
	//-------- attributes --------
	
	/** The object type. */
	protected OAVObjectType	type;
	
	/** The variable. */
	protected Variable	variable;
	
	//-------- constructors --------
	
	/**
	 *  Create a new existential declaration.
	 *  @param type	The object type.
	 *  @param variable	The variable.
	 */
	public ExistentialDeclaration(OAVObjectType type, Variable variable)
	{
		this.type	= type;
		this.variable	= variable;
	}
	
	//-------- methods --------
	
	/**
	 *  Test if a variable is contained in the expression.
	 *  @param var	The variable.
	 *  @return	True, when the variable is contained.
	 */
	public boolean	containsVariable(Variable var)
	{
		return var.equals(variable);
	}
	
	/**
	 *  Get the variable.
	 */
	public Variable	getVariable()
	{
		return this.variable;
	}
	
	/**
	 *  Get the object type.
	 */
	public OAVObjectType	getType()
	{
		return this.type;
	}
	
	/**
	 *  Get a string representation of this existential declaration.
	 */
	public String	toString()
	{
		return type.getName()+" "+variable.getName();
	}

	/**
	 *  Test if this object is equal to some object.
	 */
	public boolean	equals(Object o)
	{
		return o instanceof ExistentialDeclaration
			&& ((ExistentialDeclaration)o).getType().equals(getType())
			&& ((ExistentialDeclaration)o).getVariable().equals(getVariable());
	}
	
	/**
	 *  Get the hash code.
	 */
	public int	hashCode()
	{
		int	ret	= 31 + getType().hashCode();
		ret	= ret*31 + getVariable().hashCode();
		return ret;
	}
}