1/*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements.  See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License.  You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package org.apache.commons.math.fraction;
19
20import java.io.Serializable;
21import java.math.BigInteger;
22import java.text.FieldPosition;
23import java.text.NumberFormat;
24import java.text.ParseException;
25import java.text.ParsePosition;
26import java.util.Locale;
27
28import org.apache.commons.math.MathRuntimeException;
29import org.apache.commons.math.exception.util.LocalizedFormats;
30
31/**
32 * Formats a BigFraction number in proper format or improper format.
33 * <p>
34 * The number format for each of the whole number, numerator and,
35 * denominator can be configured.
36 * </p>
37 *
38 * @since 2.0
39 * @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $
40 */
41public class BigFractionFormat extends AbstractFormat implements Serializable {
42
43    /** Serializable version identifier */
44    private static final long serialVersionUID = -2932167925527338976L;
45
46    /**
47     * Create an improper formatting instance with the default number format
48     * for the numerator and denominator.
49     */
50    public BigFractionFormat() {
51    }
52
53    /**
54     * Create an improper formatting instance with a custom number format for
55     * both the numerator and denominator.
56     * @param format the custom format for both the numerator and denominator.
57     */
58    public BigFractionFormat(final NumberFormat format) {
59        super(format);
60    }
61
62    /**
63     * Create an improper formatting instance with a custom number format for
64     * the numerator and a custom number format for the denominator.
65     * @param numeratorFormat the custom format for the numerator.
66     * @param denominatorFormat the custom format for the denominator.
67     */
68    public BigFractionFormat(final NumberFormat numeratorFormat,
69                             final NumberFormat denominatorFormat) {
70        super(numeratorFormat, denominatorFormat);
71    }
72
73    /**
74     * Get the set of locales for which complex formats are available.  This
75     * is the same set as the {@link NumberFormat} set.
76     * @return available complex format locales.
77     */
78    public static Locale[] getAvailableLocales() {
79        return NumberFormat.getAvailableLocales();
80    }
81
82    /**
83     * This static method calls formatBigFraction() on a default instance of
84     * BigFractionFormat.
85     *
86     * @param f BigFraction object to format
87     * @return A formatted BigFraction in proper form.
88     */
89    public static String formatBigFraction(final BigFraction f) {
90        return getImproperInstance().format(f);
91    }
92
93    /**
94     * Returns the default complex format for the current locale.
95     * @return the default complex format.
96     */
97    public static BigFractionFormat getImproperInstance() {
98        return getImproperInstance(Locale.getDefault());
99    }
100
101    /**
102     * Returns the default complex format for the given locale.
103     * @param locale the specific locale used by the format.
104     * @return the complex format specific to the given locale.
105     */
106    public static BigFractionFormat getImproperInstance(final Locale locale) {
107        return new BigFractionFormat(getDefaultNumberFormat(locale));
108    }
109
110    /**
111     * Returns the default complex format for the current locale.
112     * @return the default complex format.
113     */
114    public static BigFractionFormat getProperInstance() {
115        return getProperInstance(Locale.getDefault());
116    }
117
118    /**
119     * Returns the default complex format for the given locale.
120     * @param locale the specific locale used by the format.
121     * @return the complex format specific to the given locale.
122     */
123    public static BigFractionFormat getProperInstance(final Locale locale) {
124        return new ProperBigFractionFormat(getDefaultNumberFormat(locale));
125    }
126
127    /**
128     * Formats a {@link BigFraction} object to produce a string.  The BigFraction is
129     * output in improper format.
130     *
131     * @param BigFraction the object to format.
132     * @param toAppendTo where the text is to be appended
133     * @param pos On input: an alignment field, if desired. On output: the
134     *            offsets of the alignment field
135     * @return the value passed in as toAppendTo.
136     */
137    public StringBuffer format(final BigFraction BigFraction,
138                               final StringBuffer toAppendTo, final FieldPosition pos) {
139
140        pos.setBeginIndex(0);
141        pos.setEndIndex(0);
142
143        getNumeratorFormat().format(BigFraction.getNumerator(), toAppendTo, pos);
144        toAppendTo.append(" / ");
145        getDenominatorFormat().format(BigFraction.getDenominator(), toAppendTo, pos);
146
147        return toAppendTo;
148    }
149
150    /**
151     * Formats an object and appends the result to a StringBuffer.
152     * <code>obj</code> must be either a  {@link BigFraction} object or a
153     * {@link BigInteger} object or a {@link Number} object. Any other type of
154     * object will result in an {@link IllegalArgumentException} being thrown.
155     *
156     * @param obj the object to format.
157     * @param toAppendTo where the text is to be appended
158     * @param pos On input: an alignment field, if desired. On output: the
159     *            offsets of the alignment field
160     * @return the value passed in as toAppendTo.
161     * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
162     * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
163     */
164    @Override
165    public StringBuffer format(final Object obj,
166                               final StringBuffer toAppendTo, final FieldPosition pos) {
167
168        final StringBuffer ret;
169        if (obj instanceof BigFraction) {
170            ret = format((BigFraction) obj, toAppendTo, pos);
171        } else if (obj instanceof BigInteger) {
172            ret = format(new BigFraction((BigInteger) obj), toAppendTo, pos);
173        } else if (obj instanceof Number) {
174            ret = format(new BigFraction(((Number) obj).doubleValue()),
175                         toAppendTo, pos);
176        } else {
177            throw MathRuntimeException.createIllegalArgumentException(
178                LocalizedFormats.CANNOT_FORMAT_OBJECT_TO_FRACTION);
179        }
180
181        return ret;
182    }
183
184    /**
185     * Parses a string to produce a {@link BigFraction} object.
186     * @param source the string to parse
187     * @return the parsed {@link BigFraction} object.
188     * @exception ParseException if the beginning of the specified string
189     *            cannot be parsed.
190     */
191    @Override
192    public BigFraction parse(final String source) throws ParseException {
193        final ParsePosition parsePosition = new ParsePosition(0);
194        final BigFraction result = parse(source, parsePosition);
195        if (parsePosition.getIndex() == 0) {
196            throw MathRuntimeException.createParseException(
197                    parsePosition.getErrorIndex(),
198                    LocalizedFormats.UNPARSEABLE_FRACTION_NUMBER, source);
199        }
200        return result;
201    }
202
203    /**
204     * Parses a string to produce a {@link BigFraction} object.
205     * This method expects the string to be formatted as an improper BigFraction.
206     * @param source the string to parse
207     * @param pos input/ouput parsing parameter.
208     * @return the parsed {@link BigFraction} object.
209     */
210    @Override
211    public BigFraction parse(final String source, final ParsePosition pos) {
212        final int initialIndex = pos.getIndex();
213
214        // parse whitespace
215        parseAndIgnoreWhitespace(source, pos);
216
217        // parse numerator
218        final BigInteger num = parseNextBigInteger(source, pos);
219        if (num == null) {
220            // invalid integer number
221            // set index back to initial, error index should already be set
222            // character examined.
223            pos.setIndex(initialIndex);
224            return null;
225        }
226
227        // parse '/'
228        final int startIndex = pos.getIndex();
229        final char c = parseNextCharacter(source, pos);
230        switch (c) {
231        case 0 :
232            // no '/'
233            // return num as a BigFraction
234            return new BigFraction(num);
235        case '/' :
236            // found '/', continue parsing denominator
237            break;
238        default :
239            // invalid '/'
240            // set index back to initial, error index should be the last
241            // character examined.
242            pos.setIndex(initialIndex);
243            pos.setErrorIndex(startIndex);
244            return null;
245        }
246
247        // parse whitespace
248        parseAndIgnoreWhitespace(source, pos);
249
250        // parse denominator
251        final BigInteger den = parseNextBigInteger(source, pos);
252        if (den == null) {
253            // invalid integer number
254            // set index back to initial, error index should already be set
255            // character examined.
256            pos.setIndex(initialIndex);
257            return null;
258        }
259
260        return new BigFraction(num, den);
261    }
262
263    /**
264     * Parses a string to produce a <code>BigInteger</code>.
265     * @param source the string to parse
266     * @param pos input/ouput parsing parameter.
267     * @return a parsed <code>BigInteger</code> or null if string does not
268     * contain a BigInteger at the specified position
269     */
270    protected BigInteger parseNextBigInteger(final String source,
271                                             final ParsePosition pos) {
272
273        final int start = pos.getIndex();
274         int end = (source.charAt(start) == '-') ? (start + 1) : start;
275         while((end < source.length()) &&
276               Character.isDigit(source.charAt(end))) {
277             ++end;
278         }
279
280         try {
281             BigInteger n = new BigInteger(source.substring(start, end));
282             pos.setIndex(end);
283             return n;
284         } catch (NumberFormatException nfe) {
285             pos.setErrorIndex(start);
286             return null;
287         }
288
289    }
290
291}
292