/*
 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk_internal.bidi;

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

/**
 * An {@code 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 {@code null} for the entire range, or
 * <li>the attribute value is defined and has the same non-{@code 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>
 * When getting a run with no explicit attributes specified (i.e., calling
 * {@link #getRunStart()} and {@link #getRunLimit()}), any contiguous text
 * segments having the same attributes (the same set of attribute/value pairs)
 * are treated as separate runs if the attributes have been given to those text
 * segments separately.
 *
 * <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 {@link AttributedCharacterIterator.Attribute}
 * and its subclasses, such as {@link 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 {@code AttributedCharacterIterator} and {@code AttributedString}.
	 * 
	 * @see AttributedCharacterIterator
	 * @see AttributedString
	 * @since 1.2
	 */

	public static class Attribute implements Serializable {

		/**
		 * The name of this {@code Attribute}. The name is used primarily by
		 * {@code 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<String, Attribute> instanceMap = new HashMap<>(7);

		/**
		 * Constructs an {@code Attribute} with the given name.
		 *
		 * @param name the name of {@code Attribute}
		 */
		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)} if {@code x} and {@code y} 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 {@code 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, {@code "("}, a name identifying the attribute
		 * and {@code ")"}.
		 */
		public String toString() {
			return getClass().getName() + "(" + name + ")";
		}

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

		/**
		 * Resolves instances being deserialized to the predefined constants.
		 *
		 * @return the resolved {@code Attribute} object
		 * @throws InvalidObjectException if the object to resolve is not an instance of
		 *                                {@code Attribute}
		 */
		protected Object readResolve() throws InvalidObjectException {
			if (this.getClass() != Attribute.class) {
				throw new InvalidObjectException("subclass didn't correctly implement readResolve");
			}

			Attribute instance = 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 {@link java.util.Locale 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 {@link Annotation} holding instances of
		 * {@link 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 {@link Annotation} holding a {@code null} reference.
		 * 
		 * @see Annotation
		 */
		public static final Attribute INPUT_METHOD_SEGMENT = new Attribute("input_method_segment");

		// make sure the serial version doesn't change between compiler versions
		private static final long serialVersionUID = -9142742483513960612L;

	};

	/**
	 * Returns the index of the first character of the run with respect to all
	 * attributes containing the current character.
	 *
	 * <p>
	 * Any contiguous text segments having the same attributes (the same set of
	 * attribute/value pairs) are treated as separate runs if the attributes have
	 * been given to those text segments separately.
	 *
	 * @return the index of the first character of the run
	 */
	public int getRunStart();

	/**
	 * Returns the index of the first character of the run with respect to the given
	 * {@code attribute} containing the current character.
	 *
	 * @param attribute the desired attribute.
	 * @return the index of the first character of the run
	 */
	public int getRunStart(Attribute attribute);

	/**
	 * Returns the index of the first character of the run with respect to the given
	 * {@code attributes} containing the current character.
	 *
	 * @param attributes a set of the desired attributes.
	 * @return the index of the first character of the run
	 */
	public int getRunStart(Set<? extends Attribute> attributes);

	/**
	 * Returns the index of the first character following the run with respect to
	 * all attributes containing the current character.
	 *
	 * <p>
	 * Any contiguous text segments having the same attributes (the same set of
	 * attribute/value pairs) are treated as separate runs if the attributes have
	 * been given to those text segments separately.
	 *
	 * @return the index of the first character following the run
	 */
	public int getRunLimit();

	/**
	 * Returns the index of the first character following the run with respect to
	 * the given {@code attribute} containing the current character.
	 *
	 * @param attribute the desired attribute
	 * @return the index of the first character following the run
	 */
	public int getRunLimit(Attribute attribute);

	/**
	 * Returns the index of the first character following the run with respect to
	 * the given {@code attributes} containing the current character.
	 *
	 * @param attributes a set of the desired attributes
	 * @return the index of the first character following the run
	 */
	public int getRunLimit(Set<? extends Attribute> attributes);

	/**
	 * Returns a map with the attributes defined on the current character.
	 *
	 * @return a map with the attributes defined on the current character
	 */
	public Map<Attribute, Object> getAttributes();

	/**
	 * Returns the value of the named {@code attribute} for the current character.
	 * Returns {@code null} if the {@code attribute} is not defined.
	 *
	 * @param attribute the desired attribute
	 * @return the value of the named {@code attribute} or {@code null}
	 */
	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.
	 *
	 * @return the keys of all attributes
	 */
	public Set<Attribute> getAllAttributeKeys();
};