Flag.java

/*
 * tuProlog - Copyright (C) 2001-2002  aliCE team at deis.unibo.it
 *
 * 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; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * 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 alice.tuprolog;

import java.util.HashMap;

/**
 * This class represents a Prolog flag.
 */
class Flag {
	
	private String name;
	private Struct valueList;
	private Term   value;
	private Term   defaultValue;
	private boolean modifiable;
	private String  libraryName;
	
	/**
	 * Builds a Prolog flag
	 *
	 * @param name is the name of the flag
	 * @param valueSet is the Prolog list of the possible values
	 * @param defValue is the default value
	 * @param modifiable states if the flag is modifiable
	 * @param library is the library defining the flag
	 */
	public Flag(String name, Struct valueSet, Term defValue, boolean modifiable, String library) {
		this.name = name;
		this.valueList = valueSet;
		defaultValue = defValue;
		this.modifiable = modifiable;
		libraryName = library;
		value = defValue;
	}
	
	protected Flag() {
	}
	
	/**
	 * Gets a deep copy of the flag.
	 *
	 * @return a copy of the flag
	 */
	@Override
	public Object clone() {
		Flag f = new Flag();
		f.name = name;
		f.valueList = (Struct) valueList.copy(new HashMap<Var, Var>(), Var.ORIGINAL);
		f.value = value.copy(new HashMap<Var, Var>(), Var.ORIGINAL);
		f.defaultValue = defaultValue.copy(new HashMap<Var, Var>(), Var.ORIGINAL);
		f.modifiable = modifiable;
		f.libraryName = libraryName;
		return f;
	}
	
	/**
	 * Checks if a value is valid according to flag description.
	 *
	 * @param value the possible value of the flag
	 * @return flag validity
	 */
	public boolean isValidValue(Term value) {
		for (Term t : valueList)
			if (value.match(t))
				return true;
		return false;
	}
	
	/**
	 * Gets the name of the flag.
	 *
	 * @return the name
	 */
	public String getName() {
		return name;
	}
	
	/**
	 * Gets the list of flag possible values.
	 *
	 * @return a Prolog list
	 */
	public Struct getValueList() {
		return valueList;
	}
	
	/**
	 * Sets the value of a flag.
	 *
	 * @param value new value of the flag
	 * @return true if the value is valid
	 */
	public boolean setValue(Term value) {
		if (isValidValue(value) && modifiable) {
			this.value = value;
			return true;
		} else
			return false;
	}
	
	/**
	 * Gets the current value of the flag.
	 *
	 * @return flag current value
	 */
	public Term getValue() {
		return value;
	}
	
	/**
	 * Checks if the value is modifiable.
	 * @return
	 */
	public boolean isModifiable() {
		return modifiable;
	}
	
	/**
	 * Gets the name of the library where
	 * the flag has been defined.
	 *
	 * @return the library name
	 */
	public String getLibraryName() {
		return libraryName;
	}
	
}