1/*
2 * Copyright (c) 1996, 2002, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26/*
27 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
28 * (C) Copyright IBM Corp. 1996 - All Rights Reserved
29 *
30 *   The original version of this source code and documentation is copyrighted
31 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
32 * materials are provided under terms of a License Agreement between Taligent
33 * and Sun. This technology is protected by multiple US and International
34 * patents. This notice and attribution to Taligent may not be removed.
35 *   Taligent is a registered trademark of Taligent, Inc.
36 *
37 */
38
39package java.text;
40
41/**
42 * <code>FieldPosition</code> is a simple class used by <code>Format</code>
43 * and its subclasses to identify fields in formatted output. Fields can
44 * be identified in two ways:
45 * <ul>
46 *  <li>By an integer constant, whose names typically end with
47 *      <code>_FIELD</code>. The constants are defined in the various
48 *      subclasses of <code>Format</code>.
49 *  <li>By a <code>Format.Field</code> constant, see <code>ERA_FIELD</code>
50 *      and its friends in <code>DateFormat</code> for an example.
51 * </ul>
52 * <p>
53 * <code>FieldPosition</code> keeps track of the position of the
54 * field within the formatted output with two indices: the index
55 * of the first character of the field and the index of the last
56 * character of the field.
57 *
58 * <p>
59 * One version of the <code>format</code> method in the various
60 * <code>Format</code> classes requires a <code>FieldPosition</code>
61 * object as an argument. You use this <code>format</code> method
62 * to perform partial formatting or to get information about the
63 * formatted output (such as the position of a field).
64 *
65 * <p>
66 * If you are interested in the positions of all attributes in the
67 * formatted string use the <code>Format</code> method
68 * <code>formatToCharacterIterator</code>.
69 *
70 * @author      Mark Davis
71 * @see         java.text.Format
72 */
73public class FieldPosition {
74
75    /**
76     * Input: Desired field to determine start and end offsets for.
77     * The meaning depends on the subclass of Format.
78     */
79    int field = 0;
80
81    /**
82     * Output: End offset of field in text.
83     * If the field does not occur in the text, 0 is returned.
84     */
85    int endIndex = 0;
86
87    /**
88     * Output: Start offset of field in text.
89     * If the field does not occur in the text, 0 is returned.
90     */
91    int beginIndex = 0;
92
93    /**
94     * Desired field this FieldPosition is for.
95     */
96    private Format.Field attribute;
97
98    /**
99     * Creates a FieldPosition object for the given field.  Fields are
100     * identified by constants, whose names typically end with _FIELD,
101     * in the various subclasses of Format.
102     *
103     * @see java.text.NumberFormat#INTEGER_FIELD
104     * @see java.text.NumberFormat#FRACTION_FIELD
105     * @see java.text.DateFormat#YEAR_FIELD
106     * @see java.text.DateFormat#MONTH_FIELD
107     */
108    public FieldPosition(int field) {
109        this.field = field;
110    }
111
112    /**
113     * Creates a FieldPosition object for the given field constant. Fields are
114     * identified by constants defined in the various <code>Format</code>
115     * subclasses. This is equivalent to calling
116     * <code>new FieldPosition(attribute, -1)</code>.
117     *
118     * @param attribute Format.Field constant identifying a field
119     * @since 1.4
120     */
121    public FieldPosition(Format.Field attribute) {
122        this(attribute, -1);
123    }
124
125    /**
126     * Creates a <code>FieldPosition</code> object for the given field.
127     * The field is identified by an attribute constant from one of the
128     * <code>Field</code> subclasses as well as an integer field ID
129     * defined by the <code>Format</code> subclasses. <code>Format</code>
130     * subclasses that are aware of <code>Field</code> should give precedence
131     * to <code>attribute</code> and ignore <code>fieldID</code> if
132     * <code>attribute</code> is not null. However, older <code>Format</code>
133     * subclasses may not be aware of <code>Field</code> and rely on
134     * <code>fieldID</code>. If the field has no corresponding integer
135     * constant, <code>fieldID</code> should be -1.
136     *
137     * @param attribute Format.Field constant identifying a field
138     * @param fieldID integer constantce identifying a field
139     * @since 1.4
140     */
141    public FieldPosition(Format.Field attribute, int fieldID) {
142        this.attribute = attribute;
143        this.field = fieldID;
144    }
145
146    /**
147     * Returns the field identifier as an attribute constant
148     * from one of the <code>Field</code> subclasses. May return null if
149     * the field is specified only by an integer field ID.
150     *
151     * @return Identifier for the field
152     * @since 1.4
153     */
154    public Format.Field getFieldAttribute() {
155        return attribute;
156    }
157
158    /**
159     * Retrieves the field identifier.
160     */
161    public int getField() {
162        return field;
163    }
164
165    /**
166     * Retrieves the index of the first character in the requested field.
167     */
168    public int getBeginIndex() {
169        return beginIndex;
170    }
171
172    /**
173     * Retrieves the index of the character following the last character in the
174     * requested field.
175     */
176    public int getEndIndex() {
177        return endIndex;
178    }
179
180    /**
181     * Sets the begin index.  For use by subclasses of Format.
182     * @since 1.2
183     */
184    public void setBeginIndex(int bi) {
185        beginIndex = bi;
186    }
187
188    /**
189     * Sets the end index.  For use by subclasses of Format.
190     * @since 1.2
191     */
192    public void setEndIndex(int ei) {
193        endIndex = ei;
194    }
195
196    /**
197     * Returns a <code>Format.FieldDelegate</code> instance that is associated
198     * with the FieldPosition. When the delegate is notified of the same
199     * field the FieldPosition is associated with, the begin/end will be
200     * adjusted.
201     */
202    Format.FieldDelegate getFieldDelegate() {
203        return new Delegate();
204    }
205
206    /**
207     * Overrides equals
208     */
209    public boolean equals(Object obj)
210    {
211        if (obj == null) return false;
212        if (!(obj instanceof FieldPosition))
213            return false;
214        FieldPosition other = (FieldPosition) obj;
215        if (attribute == null) {
216            if (other.attribute != null) {
217                return false;
218            }
219        }
220        else if (!attribute.equals(other.attribute)) {
221            return false;
222        }
223        return (beginIndex == other.beginIndex
224            && endIndex == other.endIndex
225            && field == other.field);
226    }
227
228    /**
229     * Returns a hash code for this FieldPosition.
230     * @return a hash code value for this object
231     */
232    public int hashCode() {
233        return (field << 24) | (beginIndex << 16) | endIndex;
234    }
235
236    /**
237     * Return a string representation of this FieldPosition.
238     * @return  a string representation of this object
239     */
240    public String toString() {
241        return getClass().getName() +
242            "[field=" + field + ",attribute=" + attribute +
243            ",beginIndex=" + beginIndex +
244            ",endIndex=" + endIndex + ']';
245    }
246
247
248    /**
249     * Return true if the receiver wants a <code>Format.Field</code> value and
250     * <code>attribute</code> is equal to it.
251     */
252    private boolean matchesField(Format.Field attribute) {
253        if (this.attribute != null) {
254            return this.attribute.equals(attribute);
255        }
256        return false;
257    }
258
259    /**
260     * Return true if the receiver wants a <code>Format.Field</code> value and
261     * <code>attribute</code> is equal to it, or true if the receiver
262     * represents an inteter constant and <code>field</code> equals it.
263     */
264    private boolean matchesField(Format.Field attribute, int field) {
265        if (this.attribute != null) {
266            return this.attribute.equals(attribute);
267        }
268        return (field == this.field);
269    }
270
271
272    /**
273     * An implementation of FieldDelegate that will adjust the begin/end
274     * of the FieldPosition if the arguments match the field of
275     * the FieldPosition.
276     */
277    private class Delegate implements Format.FieldDelegate {
278        /**
279         * Indicates whether the field has been  encountered before. If this
280         * is true, and <code>formatted</code> is invoked, the begin/end
281         * are not updated.
282         */
283        private boolean encounteredField;
284
285        public void formatted(Format.Field attr, Object value, int start,
286                              int end, StringBuffer buffer) {
287            if (!encounteredField && matchesField(attr)) {
288                setBeginIndex(start);
289                setEndIndex(end);
290                encounteredField = (start != end);
291            }
292        }
293
294        public void formatted(int fieldID, Format.Field attr, Object value,
295                              int start, int end, StringBuffer buffer) {
296            if (!encounteredField && matchesField(attr, fieldID)) {
297                setBeginIndex(start);
298                setEndIndex(end);
299                encounteredField = (start != end);
300            }
301        }
302    }
303}
304