com.topologi.diffx.event.impl.CharactersEventBase Maven / Gradle / Ivy
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/*
* This file is part of the DiffX library.
*
* For licensing information please see the file license.txt included in the release.
* A copy of this licence can also be found at
* http://www.opensource.org/licenses/artistic-license-2.0.php
*/
package com.topologi.diffx.event.impl;
import java.io.IOException;
import com.topologi.diffx.event.DiffXEvent;
import com.topologi.diffx.event.TextEvent;
import com.topologi.diffx.xml.XMLWriter;
/**
* A base class for all the characters events "characters" SAX event.
*
* @author Christophe Lauret
* @version 28 March 2010
*/
public abstract class CharactersEventBase extends DiffXEventBase implements TextEvent {
/**
* The characters for this event.
*/
private final String characters;
/**
* A suitable hashCode for this event.
*/
private final int hashCode;
/**
* Creates a new characters event.
*
* @param seq The char sequence.
*
* @throws NullPointerException If the given String is null.
*/
public CharactersEventBase(CharSequence seq) throws NullPointerException {
if (seq == null)
throw new NullPointerException("The characters cannot be null, use \"\"");
this.characters = seq.toString();
this.hashCode = toHashCode(seq);
}
/**
* {@inheritDoc}
*/
@Override
public final int hashCode() {
return this.hashCode;
}
/**
* Returns true if the event is a character event and its content is equivalent.
*
* @param e The event to compare with this event.
*
* @return true if considered equal; false otherwise.
*/
@Override
public final boolean equals(DiffXEvent e) {
if (this == e)
return true;
if (e.getClass() != this.getClass())
return false;
CharactersEventBase ce = (CharactersEventBase) e;
return ce.characters.equals(this.characters);
}
/**
* Returns the characters that this event represents.
*
*
* Note: this method will return the characters as used by Java (ie. Unicode), they may not be
* suitable for writing to an XML string.
*
* @return The characters that this event represents.
*/
public final String getCharacters() {
return this.characters;
}
/**
* {@inheritDoc}
*/
public final void toXML(XMLWriter xml) throws IOException {
xml.writeText(this.characters);
}
/**
* {@inheritDoc}
*/
public final StringBuffer toXML(StringBuffer xml) throws NullPointerException {
xml.append(ESC.toElementText(this.characters));
return xml;
}
/**
* Calculates the hashcode value from a string.
*
* @param s A string from which to calculate the hashcode.
* @return a suitable hashcode value.
*/
private static int toHashCode(CharSequence s) {
return 13 * 47 + (s != null ? s.hashCode() : 0);
}
}