/*
 * @(#)AttributedCharacterIterator.java	1.26 00/02/02
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.text;

import java.io.InvalidObjectException;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * An AttributedCharacterIterator allows iteration through both text and
 * related attribute information.
 *
 * <p>
 * An attribute is a key/value pair, identified by the key.  No two
 * attributes on a given character can have the same key.
 *
 * <p>The values for an attribute are immutable, or must not be mutated
 * by clients or storage.  They are always passed by reference, and not
 * cloned.
 *
 * <p>A <em>run with respect to an attribute</em> is a maximum text range for
 * which:
 * <ul>
 * <li>the attribute is undefined or null for the entire range, or
 * <li>the attribute value is defined and has the same non-null value for the
 *     entire range.
 * </ul>
 *
 * <p>A <em>run with respect to a set of attributes</em> is a maximum text range for
 * which this condition is met for each member attribute.
 *
 * <p>The returned indexes are limited to the range of the iterator.
 *
 * <p>The returned attribute information is limited to runs that contain
 * the current character.
 *
 * <p>
 * Attribute keys are instances of AttributedCharacterIterator.Attribute and its
 * subclasses, such as java.awt.font.TextAttribute.
 *
 * @see AttributedCharacterIterator.Attribute
 * @see java.awt.font.TextAttribute
 * @see AttributedString
 * @see Annotation
 * @since 1.2
 */

public interface AttributedCharacterIterator extends CharacterIterator {

    /**
     * Defines attribute keys that are used to identify text attributes. These
     * keys are used in AttributedCharacterIterator and AttributedString.
     * @see AttributedCharacterIterator
     * @see AttributedString
     */

    public static class Attribute implements Serializable {

        /**
         * The name of this Attribute. The name is used primarily by readResolve
         * to look up the corresponding predefined instance when deserializing
         * an instance.
         * @serial
         */
        private String name;

        // table of all instances in this class, used by readResolve
        private static final Map instanceMap = new HashMap(7);

        /**
         * Constructs an Attribute with the given name.
         */
        protected Attribute(String name) {
            this.name = name;
            if (this.getClass() == Attribute.class) {
                instanceMap.put(name, this);
            }
        }

        /**
         * Compares two objects for equality. This version only returns true
         * for <code>x.equals(y)</code> if <code>x</code> and <code>y</code> refer
         * to the same object, and guarantees this for all subclasses.
         */
        public final boolean equals(Object obj) {
            return super.equals(obj);
        }

        /**
         * Returns a hash code value for the object. This version is identical to
         * the one in Object, but is also final.
         */
        public final int hashCode() {
            return super.hashCode();
        }

        /**
         * Returns a string representation of the object. This version returns the
         * concatenation of class name, "(", a name identifying the attribute and ")".
         */
        public String toString() {
            return getClass().getName() + "(" + name + ")";
        }

        /**
         * Returns the name of the attribute.
         */
        protected String getName() {
            return name;
        }

        /**
         * Resolves instances being deserialized to the predefined constants.
         */
        protected Object readResolve() throws InvalidObjectException {
            if (this.getClass() != Attribute.class) {
                throw new InvalidObjectException("subclass didn't correctly implement readResolve");
            }

            Attribute instance = (Attribute) instanceMap.get(getName());
            if (instance != null) {
                return instance;
            } else {
                throw new InvalidObjectException("unknown attribute name");
            }
        }

        /**
         * Attribute key for the language of some text.
         * <p> Values are instances of Locale.
         * @see java.util.Locale
         */
        public static final Attribute LANGUAGE = new Attribute("language");

        /**
         * Attribute key for the reading of some text. In languages where the written form
         * and the pronunciation of a word are only loosely related (such as Japanese),
         * it is often necessary to store the reading (pronunciation) along with the
         * written form.
         * <p>Values are instances of Annotation holding instances of String.
         * @see Annotation
         * @see java.lang.String
         */
        public static final Attribute READING = new Attribute("reading");

        /**
         * Attribute key for input method segments. Input methods often break
         * up text into segments, which usually correspond to words.
         * <p>Values are instances of Annotation holding a null reference.
         * @see Annotation
         */
        public static final Attribute INPUT_METHOD_SEGMENT = new Attribute("input_method_segment");

    };

    /**
     * Returns the index of the first character of the run
     * with respect to all attributes containing the current character.
     */
    public int getRunStart();

    /**
     * Returns the index of the first character of the run
     * with respect to the given attribute containing the current character.
     */
    public int getRunStart(Attribute attribute);

    /**
     * Returns the index of the first character of the run
     * with respect to the given attributes containing the current character.
     */
    public int getRunStart(Set attributes);

    /**
     * Returns the index of the first character following the run
     * with respect to all attributes containing the current character.
     */
    public int getRunLimit();

    /**
     * Returns the index of the first character following the run
     * with respect to the given attribute containing the current character.
     */
    public int getRunLimit(Attribute attribute);

    /**
     * Returns the index of the first character following the run
     * with respect to the given attributes containing the current character.
     */
    public int getRunLimit(Set attributes);

    /**
     * Returns a map with the attributes defined on the current
     * character.
     */
    public Map getAttributes();

    /**
     * Returns the value of the named attribute for the current character.
     * Returns null if the attribute is not defined.
     * @param attribute the key of the attribute whose value is requested.
     */
    public Object getAttribute(Attribute attribute);

    /**
     * Returns the keys of all attributes defined on the
     * iterator's text range. The set is empty if no
     * attributes are defined.
     */
    public Set getAllAttributeKeys();
};