1/*
2 * Copyright (c) 1996, 2013, 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 * @since 1.1
72 * @see         java.text.Format
73 */
74public class FieldPosition {
75
76    /**
77     * Input: Desired field to determine start and end offsets for.
78     * The meaning depends on the subclass of Format.
79     */
80    int field = 0;
81
82    /**
83     * Output: End offset of field in text.
84     * If the field does not occur in the text, 0 is returned.
85     */
86    int endIndex = 0;
87
88    /**
89     * Output: Start offset of field in text.
90     * If the field does not occur in the text, 0 is returned.
91     */
92    int beginIndex = 0;
93
94    /**
95     * Desired field this FieldPosition is for.
96     */
97    private Format.Field attribute;
98
99    /**
100     * Creates a FieldPosition object for the given field.  Fields are
101     * identified by constants, whose names typically end with _FIELD,
102     * in the various subclasses of Format.
103     *
104     * @param field the field identifier
105     * @see java.text.NumberFormat#INTEGER_FIELD
106     * @see java.text.NumberFormat#FRACTION_FIELD
107     * @see java.text.DateFormat#YEAR_FIELD
108     * @see java.text.DateFormat#MONTH_FIELD
109     */
110    public FieldPosition(int field) {
111        this.field = field;
112    }
113
114    /**
115     * Creates a FieldPosition object for the given field constant. Fields are
116     * identified by constants defined in the various <code>Format</code>
117     * subclasses. This is equivalent to calling
118     * <code>new FieldPosition(attribute, -1)</code>.
119     *
120     * @param attribute Format.Field constant identifying a field
121     * @since 1.4
122     */
123    public FieldPosition(Format.Field attribute) {
124        this(attribute, -1);
125    }
126
127    /**
128     * Creates a <code>FieldPosition</code> object for the given field.
129     * The field is identified by an attribute constant from one of the
130     * <code>Field</code> subclasses as well as an integer field ID
131     * defined by the <code>Format</code> subclasses. <code>Format</code>
132     * subclasses that are aware of <code>Field</code> should give precedence
133     * to <code>attribute</code> and ignore <code>fieldID</code> if
134     * <code>attribute</code> is not null. However, older <code>Format</code>
135     * subclasses may not be aware of <code>Field</code> and rely on
136     * <code>fieldID</code>. If the field has no corresponding integer
137     * constant, <code>fieldID</code> should be -1.
138     *
139     * @param attribute Format.Field constant identifying a field
140     * @param fieldID integer constant identifying a field
141     * @since 1.4
142     */
143    public FieldPosition(Format.Field attribute, int fieldID) {
144        this.attribute = attribute;
145        this.field = fieldID;
146    }
147
148    /**
149     * Returns the field identifier as an attribute constant
150     * from one of the <code>Field</code> subclasses. May return null if
151     * the field is specified only by an integer field ID.
152     *
153     * @return Identifier for the field
154     * @since 1.4
155     */
156    public Format.Field getFieldAttribute() {
157        return attribute;
158    }
159
160    /**
161     * Retrieves the field identifier.
162     *
163     * @return the field identifier
164     */
165    public int getField() {
166        return field;
167    }
168
169    /**
170     * Retrieves the index of the first character in the requested field.
171     *
172     * @return the begin index
173     */
174    public int getBeginIndex() {
175        return beginIndex;
176    }
177
178    /**
179     * Retrieves the index of the character following the last character in the
180     * requested field.
181     *
182     * @return the end index
183     */
184    public int getEndIndex() {
185        return endIndex;
186    }
187
188    /**
189     * Sets the begin index.  For use by subclasses of Format.
190     *
191     * @param bi the begin index
192     * @since 1.2
193     */
194    public void setBeginIndex(int bi) {
195        beginIndex = bi;
196    }
197
198    /**
199     * Sets the end index.  For use by subclasses of Format.
200     *
201     * @param ei the end index
202     * @since 1.2
203     */
204    public void setEndIndex(int ei) {
205        endIndex = ei;
206    }
207
208    /**
209     * Returns a <code>Format.FieldDelegate</code> instance that is associated
210     * with the FieldPosition. When the delegate is notified of the same
211     * field the FieldPosition is associated with, the begin/end will be
212     * adjusted.
213     */
214    Format.FieldDelegate getFieldDelegate() {
215        return new Delegate();
216    }
217
218    /**
219     * Overrides equals
220     */
221    public boolean equals(Object obj)
222    {
223        if (obj == null) return false;
224        if (!(obj instanceof FieldPosition))
225            return false;
226        FieldPosition other = (FieldPosition) obj;
227        if (attribute == null) {
228            if (other.attribute != null) {
229                return false;
230            }
231        }
232        else if (!attribute.equals(other.attribute)) {
233            return false;
234        }
235        return (beginIndex == other.beginIndex
236            && endIndex == other.endIndex
237            && field == other.field);
238    }
239
240    /**
241     * Returns a hash code for this FieldPosition.
242     * @return a hash code value for this object
243     */
244    public int hashCode() {
245        return (field << 24) | (beginIndex << 16) | endIndex;
246    }
247
248    /**
249     * Return a string representation of this FieldPosition.
250     * @return  a string representation of this object
251     */
252    public String toString() {
253        return getClass().getName() +
254            "[field=" + field + ",attribute=" + attribute +
255            ",beginIndex=" + beginIndex +
256            ",endIndex=" + endIndex + ']';
257    }
258
259
260    /**
261     * Return true if the receiver wants a <code>Format.Field</code> value and
262     * <code>attribute</code> is equal to it.
263     */
264    private boolean matchesField(Format.Field attribute) {
265        if (this.attribute != null) {
266            return this.attribute.equals(attribute);
267        }
268        return false;
269    }
270
271    /**
272     * Return true if the receiver wants a <code>Format.Field</code> value and
273     * <code>attribute</code> is equal to it, or true if the receiver
274     * represents an inteter constant and <code>field</code> equals it.
275     */
276    private boolean matchesField(Format.Field attribute, int field) {
277        if (this.attribute != null) {
278            return this.attribute.equals(attribute);
279        }
280        return (field == this.field);
281    }
282
283
284    /**
285     * An implementation of FieldDelegate that will adjust the begin/end
286     * of the FieldPosition if the arguments match the field of
287     * the FieldPosition.
288     */
289    private class Delegate implements Format.FieldDelegate {
290        /**
291         * Indicates whether the field has been  encountered before. If this
292         * is true, and <code>formatted</code> is invoked, the begin/end
293         * are not updated.
294         */
295        private boolean encounteredField;
296
297        public void formatted(Format.Field attr, Object value, int start,
298                              int end, StringBuffer buffer) {
299            if (!encounteredField && matchesField(attr)) {
300                setBeginIndex(start);
301                setEndIndex(end);
302                encounteredField = (start != end);
303            }
304        }
305
306        public void formatted(int fieldID, Format.Field attr, Object value,
307                              int start, int end, StringBuffer buffer) {
308            if (!encounteredField && matchesField(attr, fieldID)) {
309                setBeginIndex(start);
310                setEndIndex(end);
311                encounteredField = (start != end);
312            }
313        }
314    }
315}
316