/*

 * Copyright 1996-2002 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - All Rights Reserved

 *

 *   The original version of this source code and documentation is copyrighted

 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These

 * materials are provided under terms of a License Agreement between Taligent

 * and Sun. This technology is protected by multiple US and International

 * patents. This notice and attribution to Taligent may not be removed.

 *   Taligent is a registered trademark of Taligent, Inc.

 *

 */

package java.text;

/**

 * <code>FieldPosition</code> is a simple class used by <code>Format</code>

 * and its subclasses to identify fields in formatted output. Fields can

 * be identified in two ways:

 * <ul>

 *  <li>By an integer constant, whose names typically end with

 *      <code>_FIELD</code>. The constants are defined in the various

 *      subclasses of <code>Format</code>.

 *  <li>By a <code>Format.Field</code> constant, see <code>ERA_FIELD</code>

 *      and its friends in <code>DateFormat</code> for an example.

 * </ul>

 * <p>

 * <code>FieldPosition</code> keeps track of the position of the

 * field within the formatted output with two indices: the index

 * of the first character of the field and the index of the last

 * character of the field.

 *

 * <p>

 * One version of the <code>format</code> method in the various

 * <code>Format</code> classes requires a <code>FieldPosition</code>

 * object as an argument. You use this <code>format</code> method

 * to perform partial formatting or to get information about the

 * formatted output (such as the position of a field).

 *

 * <p>

 * If you are interested in the positions of all attributes in the

 * formatted string use the <code>Format</code> method

 * <code>formatToCharacterIterator</code>.

 *

 * @author      Mark Davis

 * @see         java.text.Format

 */

public class FieldPosition {

    /**

     * Input: Desired field to determine start and end offsets for.

     * The meaning depends on the subclass of Format.

     */

    int field = 0;

    /**

     * Output: End offset of field in text.

     * If the field does not occur in the text, 0 is returned.

     */

    int endIndex = 0;

    /**

     * Output: Start offset of field in text.

     * If the field does not occur in the text, 0 is returned.

     */

    int beginIndex = 0;

    /**

     * Desired field this FieldPosition is for.

     */

    private Format.Field attribute;

    /**

     * Creates a FieldPosition object for the given field.  Fields are

     * identified by constants, whose names typically end with _FIELD,

     * in the various subclasses of Format.

     *

     * @see java.text.NumberFormat#INTEGER_FIELD

     * @see java.text.NumberFormat#FRACTION_FIELD

     * @see java.text.DateFormat#YEAR_FIELD

     * @see java.text.DateFormat#MONTH_FIELD

     */

    public FieldPosition(int field) {

        this.field = field;

    }

    /**

     * Creates a FieldPosition object for the given field constant. Fields are

     * identified by constants defined in the various <code>Format</code>

     * subclasses. This is equivalent to calling

     * <code>new FieldPosition(attribute, -1)</code>.

     *

     * @param attribute Format.Field constant identifying a field

     * @since 1.4

     */

    public FieldPosition(Format.Field attribute) {

        this(attribute, -1);

    }

    /**

     * Creates a <code>FieldPosition</code> object for the given field.

     * The field is identified by an attribute constant from one of the

     * <code>Field</code> subclasses as well as an integer field ID

     * defined by the <code>Format</code> subclasses. <code>Format</code>

     * subclasses that are aware of <code>Field</code> should give precedence

     * to <code>attribute</code> and ignore <code>fieldID</code> if

     * <code>attribute</code> is not null. However, older <code>Format</code>

     * subclasses may not be aware of <code>Field</code> and rely on

     * <code>fieldID</code>. If the field has no corresponding integer

     * constant, <code>fieldID</code> should be -1.

     *

     * @param attribute Format.Field constant identifying a field

     * @param fieldID integer constantce identifying a field

     * @since 1.4

     */

    public FieldPosition(Format.Field attribute, int fieldID) {

        this.attribute = attribute;

        this.field = fieldID;

    }

    /**

     * Returns the field identifier as an attribute constant

     * from one of the <code>Field</code> subclasses. May return null if

     * the field is specified only by an integer field ID.

     *

     * @return Identifier for the field

     * @since 1.4

     */

    public Format.Field getFieldAttribute() {

        return attribute;

    }

    /**

     * Retrieves the field identifier.

     */

    public int getField() {

        return field;

    }

    /**

     * Retrieves the index of the first character in the requested field.

     */

    public int getBeginIndex() {

        return beginIndex;

    }

    /**

     * Retrieves the index of the character following the last character in the

     * requested field.

     */

    public int getEndIndex() {

        return endIndex;

    }

    /**

     * Sets the begin index.  For use by subclasses of Format.

     * @since 1.2

     */

    public void setBeginIndex(int bi) {

        beginIndex = bi;

    }

    /**

     * Sets the end index.  For use by subclasses of Format.

     * @since 1.2

     */

    public void setEndIndex(int ei) {

        endIndex = ei;

    }

    /**

     * Returns a <code>Format.FieldDelegate</code> instance that is associated

     * with the FieldPosition. When the delegate is notified of the same

     * field the FieldPosition is associated with, the begin/end will be

     * adjusted.

     */

    Format.FieldDelegate getFieldDelegate() {

        return new Delegate();

    }

    /**

     * Overrides equals

     */

    public boolean equals(Object obj)

    {

        if (obj == null) return false;

        if (!(obj instanceof FieldPosition))

            return false;

        FieldPosition other = (FieldPosition) obj;

        if (attribute == null) {

            if (other.attribute != null) {

                return false;

            }

        }

        else if (!attribute.equals(other.attribute)) {

            return false;

        }

        return (beginIndex == other.beginIndex

            && endIndex == other.endIndex

            && field == other.field);

    }

    /**

     * Returns a hash code for this FieldPosition.

     * @return a hash code value for this object

     */

    public int hashCode() {

        return (field << 24) | (beginIndex << 16) | endIndex;

    }

    /**

     * Return a string representation of this FieldPosition.

     * @return  a string representation of this object

     */

    public String toString() {

        return getClass().getName() +

            "[field=" + field + ",attribute=" + attribute +

            ",beginIndex=" + beginIndex +

            ",endIndex=" + endIndex + ']';

    }

    /**

     * Return true if the receiver wants a <code>Format.Field</code> value and

     * <code>attribute</code> is equal to it.

     */

    private boolean matchesField(Format.Field attribute) {

        if (this.attribute != null) {

            return this.attribute.equals(attribute);

        }

        return false;

    }

    /**

     * Return true if the receiver wants a <code>Format.Field</code> value and

     * <code>attribute</code> is equal to it, or true if the receiver

     * represents an inteter constant and <code>field</code> equals it.

     */

    private boolean matchesField(Format.Field attribute, int field) {

        if (this.attribute != null) {

            return this.attribute.equals(attribute);

        }

        return (field == this.field);

    }

    /**

     * An implementation of FieldDelegate that will adjust the begin/end

     * of the FieldPosition if the arguments match the field of

     * the FieldPosition.

     */

    private class Delegate implements Format.FieldDelegate {

        /**

         * Indicates whether the field has been  encountered before. If this

         * is true, and <code>formatted</code> is invoked, the begin/end

         * are not updated.

         */

        private boolean encounteredField;

        public void formatted(Format.Field attr, Object value, int start,

                              int end, StringBuffer buffer) {

            if (!encounteredField && matchesField(attr)) {

                setBeginIndex(start);

                setEndIndex(end);

                encounteredField = (start != end);

            }

        }

        public void formatted(int fieldID, Format.Field attr, Object value,

                              int start, int end, StringBuffer buffer) {

            if (!encounteredField && matchesField(attr, fieldID)) {

                setBeginIndex(start);

                setEndIndex(end);

                encounteredField = (start != end);

            }

        }

    }

}