/*
* @(#)SimpleAttributeSet.java 1.41 04/05/05
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.text;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
* A straightforward implementation of MutableAttributeSet using a
* hash table.
* <p>
* <strong>Warning:</strong>
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeans<sup><font size="-2">TM</font></sup>
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*
* @version 1.41 05/05/04
* @author Tim Prinzing
*/
public class SimpleAttributeSet implements MutableAttributeSet, Serializable, Cloneable
{
/**
* An empty attribute set.
*/
public static final AttributeSet EMPTY = new EmptyAttributeSet();
private transient Hashtable table = new Hashtable(3);
private static Enumeration emptyEnumeration;
/**
* Creates a new attribute set.
*/
public SimpleAttributeSet() {
}
/**
* Creates a new attribute set based on a supplied set of attributes.
*
* @param source the set of attributes
*/
public SimpleAttributeSet(AttributeSet source) {
addAttributes(source);
}
private SimpleAttributeSet(Hashtable table) {
this.table = table;
}
/**
* Checks whether the set of attributes is empty.
*
* @return true if the set is empty else false
*/
public boolean isEmpty()
{
return table.isEmpty();
}
/**
* Gets a count of the number of attributes.
*
* @return the count
*/
public int getAttributeCount() {
return table.size();
}
/**
* Tells whether a given attribute is defined.
*
* @param attrName the attribute name
* @return true if the attribute is defined
*/
public boolean isDefined(Object attrName) {
return table.containsKey(attrName);
}
/**
* Compares two attribute sets.
*
* @param attr the second attribute set
* @return true if the sets are equal, false otherwise
*/
public boolean isEqual(AttributeSet attr) {
return ((getAttributeCount() == attr.getAttributeCount()) &&
containsAttributes(attr));
}
/**
* Makes a copy of the attributes.
*
* @return the copy
*/
public AttributeSet copyAttributes() {
return (AttributeSet) clone();
}
/**
* Gets the names of the attributes in the set.
*
* @return the names as an <code>Enumeration</code>
*/
public Enumeration<?> getAttributeNames() {
return table.keys();
}
/**
* Gets the value of an attribute.
*
* @param name the attribute name
* @return the value
*/
public Object getAttribute(Object name) {
Object value = table.get(name);
if (value == null) {
AttributeSet parent = getResolveParent();
if (parent != null) {
value = parent.getAttribute(name);
}
}
return value;
}
/**
* Checks whether the attribute list contains a
* specified attribute name/value pair.
*
* @param name the name
* @param value the value
* @return true if the name/value pair is in the list
*/
public boolean containsAttribute(Object name, Object value) {
return value.equals(getAttribute(name));
}
/**
* Checks whether the attribute list contains all the
* specified name/value pairs.
*
* @param attributes the attribute list
* @return true if the list contains all the name/value pairs
*/
public boolean containsAttributes(AttributeSet attributes) {
boolean result = true;
Enumeration names = attributes.getAttributeNames();
while (result && names.hasMoreElements()) {
Object name = names.nextElement();
result = attributes.getAttribute(name).equals(getAttribute(name));
}
return result;
}
/**
* Adds an attribute to the list.
*
* @param name the attribute name
* @param value the attribute value
*/
public void addAttribute(Object name, Object value) {
table.put(name, value);
}
/**
* Adds a set of attributes to the list.
*
* @param attributes the set of attributes to add
*/
public void addAttributes(AttributeSet attributes) {
Enumeration names = attributes.getAttributeNames();
while (names.hasMoreElements()) {
Object name = names.nextElement();
addAttribute(name, attributes.getAttribute(name));
}
}
/**
* Removes an attribute from the list.
*
* @param name the attribute name
*/
public void removeAttribute(Object name) {
table.remove(name);
}
/**
* Removes a set of attributes from the list.
*
* @param names the set of names to remove
*/
public void removeAttributes(Enumeration<?> names) {
while (names.hasMoreElements())
removeAttribute(names.nextElement());
}
/**
* Removes a set of attributes from the list.
*
* @param attributes the set of attributes to remove
*/
public void removeAttributes(AttributeSet attributes) {
if (attributes == this) {
table.clear();
}
else {
Enumeration names = attributes.getAttributeNames();
while (names.hasMoreElements()) {
Object name = names.nextElement();
Object value = attributes.getAttribute(name);
if (value.equals(getAttribute(name)))
removeAttribute(name);
}
}
}
/**
* Gets the resolving parent. This is the set
* of attributes to resolve through if an attribute
* isn't defined locally. This is null if there
* are no other sets of attributes to resolve
* through.
*
* @return the parent
*/
public AttributeSet getResolveParent() {
return (AttributeSet) table.get(StyleConstants.ResolveAttribute);
}
/**
* Sets the resolving parent.
*
* @param parent the parent
*/
public void setResolveParent(AttributeSet parent) {
addAttribute(StyleConstants.ResolveAttribute, parent);
}
// --- Object methods ---------------------------------
/**
* Clones a set of attributes.
*
* @return the new set of attributes
*/
public Object clone() {
SimpleAttributeSet attr;
try {
attr = (SimpleAttributeSet) super.clone();
attr.table = (Hashtable) table.clone();
} catch (CloneNotSupportedException cnse) {
attr = null;
}
return attr;
}
/**
* Returns a hashcode for this set of attributes.
* @return a hashcode value for this set of attributes.
*/
public int hashCode() {
return table.hashCode();
}
/**
* Compares this object to the specified object.
* The result is <code>true</code> if the object is an equivalent
* set of attributes.
* @param obj the object to compare this attribute set with
* @return <code>true</code> if the objects are equal;
* <code>false</code> otherwise
*/
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof AttributeSet) {
AttributeSet attrs = (AttributeSet) obj;
return isEqual(attrs);
}
return false;
}
/**
* Converts the attribute set to a String.
*
* @return the string
*/
public String toString() {
String s = "";
Enumeration names = getAttributeNames();
while (names.hasMoreElements()) {
Object key = names.nextElement();
Object value = getAttribute(key);
if (value instanceof AttributeSet) {
// don't go recursive
s = s + key + "=**AttributeSet** ";
} else {
s = s + key + "=" + value + " ";
}
}
return s;
}
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
StyleContext.writeAttributeSet(s, this);
}
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException {
s.defaultReadObject();
table = new Hashtable(3);
StyleContext.readAttributeSet(s, this);
}
/**
* An AttributeSet this is always empty.
*/
static class EmptyAttributeSet implements AttributeSet, Serializable {
public int getAttributeCount() {
return 0;
}
public boolean isDefined(Object attrName) {
return false;
}
public boolean isEqual(AttributeSet attr) {
return (attr.getAttributeCount() == 0);
}
public AttributeSet copyAttributes() {
return this;
}
public Object getAttribute(Object key) {
return null;
}
public Enumeration getAttributeNames() {
return getEmptyEnumeration();
}
public boolean containsAttribute(Object name, Object value) {
return false;
}
public boolean containsAttributes(AttributeSet attributes) {
return (attributes.getAttributeCount() == 0);
}
public AttributeSet getResolveParent() {
return null;
}
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
return ((obj instanceof AttributeSet) &&
(((AttributeSet)obj).getAttributeCount() == 0));
}
public int hashCode() {
return 0;
}
};
private static Enumeration getEmptyEnumeration() {
if (emptyEnumeration == null) {
emptyEnumeration = new Enumeration() {
public boolean hasMoreElements() {
return false;
}
public Object nextElement() {
throw new NoSuchElementException("No more elements");
}
};
}
return emptyEnumeration;
}
}
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