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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 *
 * This code 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 General Public License
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 * accompanied this code).
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package javax.swing.text;

import java.util.Hashtable;
import java.util.Enumeration;
import java.util.Collections;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.LinkedHashMap;

A straightforward implementation of MutableAttributeSet using a
hash table.

Warning:
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™
has been added to the java.beans package. Please see XMLEncoder. 
Author:
Tim Prinzing/**
 * 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&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Tim Prinzing
 */
@SuppressWarnings("serial") // Same-version serialization only
public class SimpleAttributeSet implements MutableAttributeSet, Serializable, Cloneable
{
    private static final long serialVersionUID = -6631553454711782652L;

    
An empty attribute set.
/**
     * An empty attribute set.
     */
    public static final AttributeSet EMPTY = new EmptyAttributeSet();

    private transient LinkedHashMap<Object, Object> table = new LinkedHashMap<>(3);

    
Creates a new attribute set.
/**
     * Creates a new attribute set.
     */
    public SimpleAttributeSet() {
    }

    
Creates a new attribute set based on a supplied set of attributes.
Params:
source – the set of attributes/**
     * Creates a new attribute set based on a supplied set of attributes.
     *
     * @param source the set of attributes
     */
    public SimpleAttributeSet(AttributeSet source) {
        addAttributes(source);
    }

    
Checks whether the set of attributes is empty.
Returns:
true if the set is empty else false/**
     * 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.
Returns:
the count/**
     * Gets a count of the number of attributes.
     *
     * @return the count
     */
    public int getAttributeCount() {
        return table.size();
    }

    
Tells whether a given attribute is defined.
Params:
attrName – the attribute name
Returns:
true if the attribute is defined/**
     * 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.
Params:
attr – the second attribute set
Returns:
true if the sets are equal, false otherwise/**
     * 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.
Returns:
the copy/**
     * Makes a copy of the attributes.
     *
     * @return the copy
     */
    public AttributeSet copyAttributes() {
        return (AttributeSet) clone();
    }

    
Gets the names of the attributes in the set.
Returns:
the names as an Enumeration/**
     * Gets the names of the attributes in the set.
     *
     * @return the names as an <code>Enumeration</code>
     */
    public Enumeration<?> getAttributeNames() {
        return Collections.enumeration(table.keySet());
    }

    
Gets the value of an attribute.
Params:
name – the attribute name
Returns:
the value/**
     * 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.
Params:
name – the name
value – the value
Returns:
true if the name/value pair is in the list/**
     * 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.
Params:
attributes – the attribute list
Returns:
true if the list contains all the name/value pairs/**
     * 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.
Params:
name – the attribute name
value – the attribute value/**
     * 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.
Params:
attributes – the set of attributes to add/**
     * 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.
Params:
name – the attribute 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.
Params:
names – the set of names to remove/**
     * 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.
Params:
attributes – the set of attributes to remove/**
     * 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.
Returns:
the parent/**
     * 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.
Params:
parent – the parent/**
     * Sets the resolving parent.
     *
     * @param parent the parent
     */
    public void setResolveParent(AttributeSet parent) {
        addAttribute(StyleConstants.ResolveAttribute, parent);
    }

    // --- Object methods ---------------------------------

    
Clones a set of attributes.
Returns:
the new set of attributes/**
     * Clones a set of attributes.
     *
     * @return the new set of attributes
     */
    @SuppressWarnings("unchecked") // Cast of result of clone
    public Object clone() {
        SimpleAttributeSet attr;
        try {
            attr = (SimpleAttributeSet) super.clone();
            attr.table = (LinkedHashMap) table.clone();
        } catch (CloneNotSupportedException cnse) {
            attr = null;
        }
        return attr;
    }

    
Returns a hashcode for this set of attributes.
Returns:
    a hashcode value for this set of attributes./**
     * 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 true if the object is an equivalent
set of attributes.
Params:
obj –   the object to compare this attribute set with
Returns:
   true if the objects are equal;
           false otherwise/**
     * 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.
Returns:
the string/**
     * 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 LinkedHashMap<>(3);
        StyleContext.readAttributeSet(s, this);
    }

    
An AttributeSet that is always empty.
/**
     * An AttributeSet that is always empty.
     */
    static class EmptyAttributeSet implements AttributeSet, Serializable {
        static final long serialVersionUID = -8714803568785904228L;

        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 Collections.emptyEnumeration();
        }
        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;
        }
    }
}