001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math.fraction;
019
020 import java.io.Serializable;
021 import java.text.FieldPosition;
022 import java.text.NumberFormat;
023 import java.text.ParsePosition;
024 import java.util.Locale;
025
026 import org.apache.commons.math.MathRuntimeException;
027
028 /**
029 * Common part shared by both {@link FractionFormat} and {@link BigFractionFormat}.
030 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
031 * @since 2.0
032 */
033 public abstract class AbstractFormat extends NumberFormat implements Serializable {
034
035 /** Serializable version identifier. */
036 private static final long serialVersionUID = -6981118387974191891L;
037
038 /** The format used for the denominator. */
039 protected NumberFormat denominatorFormat;
040
041 /** The format used for the numerator. */
042 protected NumberFormat numeratorFormat;
043
044 /**
045 * Create an improper formatting instance with the default number format
046 * for the numerator and denominator.
047 */
048 protected AbstractFormat() {
049 this(getDefaultNumberFormat());
050 }
051
052 /**
053 * Create an improper formatting instance with a custom number format for
054 * both the numerator and denominator.
055 * @param format the custom format for both the numerator and denominator.
056 */
057 protected AbstractFormat(final NumberFormat format) {
058 this(format, (NumberFormat) format.clone());
059 }
060
061 /**
062 * Create an improper formatting instance with a custom number format for
063 * the numerator and a custom number format for the denominator.
064 * @param numeratorFormat the custom format for the numerator.
065 * @param denominatorFormat the custom format for the denominator.
066 */
067 protected AbstractFormat(final NumberFormat numeratorFormat,
068 final NumberFormat denominatorFormat) {
069 this.numeratorFormat = numeratorFormat;
070 this.denominatorFormat = denominatorFormat;
071 }
072
073 /**
074 * Create a default number format. The default number format is based on
075 * {@link NumberFormat#getNumberInstance(java.util.Locale)} with the only
076 * customizing is the maximum number of BigFraction digits, which is set to 0.
077 * @return the default number format.
078 */
079 protected static NumberFormat getDefaultNumberFormat() {
080 return getDefaultNumberFormat(Locale.getDefault());
081 }
082
083 /**
084 * Create a default number format. The default number format is based on
085 * {@link NumberFormat#getNumberInstance(java.util.Locale)} with the only
086 * customizing is the maximum number of BigFraction digits, which is set to 0.
087 * @param locale the specific locale used by the format.
088 * @return the default number format specific to the given locale.
089 */
090 protected static NumberFormat getDefaultNumberFormat(final Locale locale) {
091 final NumberFormat nf = NumberFormat.getNumberInstance(locale);
092 nf.setMaximumFractionDigits(0);
093 nf.setParseIntegerOnly(true);
094 return nf;
095 }
096
097 /**
098 * Access the denominator format.
099 * @return the denominator format.
100 */
101 public NumberFormat getDenominatorFormat() {
102 return denominatorFormat;
103 }
104
105 /**
106 * Access the numerator format.
107 * @return the numerator format.
108 */
109 public NumberFormat getNumeratorFormat() {
110 return numeratorFormat;
111 }
112
113 /**
114 * Modify the denominator format.
115 * @param format the new denominator format value.
116 * @throws IllegalArgumentException if <code>format</code> is
117 * <code>null</code>.
118 */
119 public void setDenominatorFormat(final NumberFormat format) {
120 if (format == null) {
121 throw MathRuntimeException.createIllegalArgumentException(
122 "denominator format can not be null");
123 }
124 this.denominatorFormat = format;
125 }
126
127 /**
128 * Modify the numerator format.
129 * @param format the new numerator format value.
130 * @throws IllegalArgumentException if <code>format</code> is
131 * <code>null</code>.
132 */
133 public void setNumeratorFormat(final NumberFormat format) {
134 if (format == null) {
135 throw MathRuntimeException.createIllegalArgumentException(
136 "numerator format can not be null");
137 }
138 this.numeratorFormat = format;
139 }
140
141 /**
142 * Parses <code>source</code> until a non-whitespace character is found.
143 * @param source the string to parse
144 * @param pos input/ouput parsing parameter. On output, <code>pos</code>
145 * holds the index of the next non-whitespace character.
146 */
147 protected static void parseAndIgnoreWhitespace(final String source,
148 final ParsePosition pos) {
149 parseNextCharacter(source, pos);
150 pos.setIndex(pos.getIndex() - 1);
151 }
152
153 /**
154 * Parses <code>source</code> until a non-whitespace character is found.
155 * @param source the string to parse
156 * @param pos input/ouput parsing parameter.
157 * @return the first non-whitespace character.
158 */
159 protected static char parseNextCharacter(final String source,
160 final ParsePosition pos) {
161 int index = pos.getIndex();
162 final int n = source.length();
163 char ret = 0;
164
165 if (index < n) {
166 char c;
167 do {
168 c = source.charAt(index++);
169 } while (Character.isWhitespace(c) && index < n);
170 pos.setIndex(index);
171
172 if (index < n) {
173 ret = c;
174 }
175 }
176
177 return ret;
178 }
179
180 /**
181 * Formats a double value as a fraction and appends the result to a StringBuffer.
182 *
183 * @param value the double value to format
184 * @param buffer StringBuffer to append to
185 * @param position On input: an alignment field, if desired. On output: the
186 * offsets of the alignment field
187 * @return a reference to the appended buffer
188 * @see #format(Object, StringBuffer, FieldPosition)
189 */
190 @Override
191 public StringBuffer format(final double value,
192 final StringBuffer buffer, final FieldPosition position) {
193 return format(Double.valueOf(value), buffer, position);
194 }
195
196
197 /**
198 * Formats a long value as a fraction and appends the result to a StringBuffer.
199 *
200 * @param value the long value to format
201 * @param buffer StringBuffer to append to
202 * @param position On input: an alignment field, if desired. On output: the
203 * offsets of the alignment field
204 * @return a reference to the appended buffer
205 * @see #format(Object, StringBuffer, FieldPosition)
206 */
207 @Override
208 public StringBuffer format(final long value,
209 final StringBuffer buffer, final FieldPosition position) {
210 return format(Long.valueOf(value), buffer, position);
211 }
212
213 }