xmlstartofelement.java

JAVA在编译原理上的应用。

package lolo.scans;

/** A recognizer to scan for <tt>&lt;aElementName</tt>. 
 *
 * @author <a href="http://www.inf.uos.de/bernd" target="_blank">Bernd K&uuml;hl</a>
           (<a href="mailto:[e-mail]">[e-mail]</a>)
 */
public class XMLStartOfElement extends Word {
    /** To mark the start of a scan. */
    protected boolean start = true;
    
    /** Constructs a <tt>XMLStartOfElement</tt> to the start of the element <tt>elementName</tt>.
     *
     * @param elementName the element name.
     * @throws IllegalArgumentException if <tt>elementName</tt> is <tt>null</tt> or contains no character.
     */
	public XMLStartOfElement(String elementName) throws IllegalArgumentException {
        super(elementName);
	}
        
	public void reset() {
        super.reset();
        start = true;
	}
        
	public State nextChar(char ch) {
        if (start) {
            start = false;
            return stateObject.set(
                ch == '<',  // need more?
                false       // found
            );
        }
        return super.nextChar(ch);
	}
    
	public String toString() {
        return getClass().getName()+"[<"+word+"]";
	}   
    
    private static final int ltHashCode = new Character('<').hashCode();
    /** Returns a hash code for the object.
     *
     * @return a hash code for the object.
     */
    public int hashCode() {
        return ltHashCode/2+super.hashCode()/2;
    }
    /** Indicates whether some other object is "equal to" this one.
     *
     * @return <tt>true</tt> if the receiver and <tt>obj</tt> are from the same class
     * and if the element names are the same, <tt>false</tt> otherwise.
     */
    public boolean equals(Object obj) {
        if (obj == null || !(obj instanceof XMLStartOfElement)) return false;
        return super.equals(obj);
    }
}