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.complex;
019    
020    import java.text.FieldPosition;
021    import java.text.NumberFormat;
022    import java.text.ParseException;
023    import java.text.ParsePosition;
024    import java.util.Locale;
025    
026    import org.apache.commons.math.MathRuntimeException;
027    import org.apache.commons.math.util.CompositeFormat;
028    
029    /**
030     * Formats a Complex number in cartesian format "Re(c) + Im(c)i".  'i' can
031     * be replaced with 'j' (or anything else), and the number format for both real
032     * and imaginary parts can be configured.
033     *
034     * @author Apache Software Foundation
035     * @version $Revision: 772119 $ $Date: 2009-05-06 05:43:28 -0400 (Wed, 06 May 2009) $
036     */
037    public class ComplexFormat extends CompositeFormat {
038        
039        /** Serializable version identifier */
040        private static final long serialVersionUID = -3343698360149467646L;
041    
042         /** The default imaginary character. */
043        private static final String DEFAULT_IMAGINARY_CHARACTER = "i";
044        
045        /** The notation used to signify the imaginary part of the complex number. */
046        private String imaginaryCharacter;
047        
048        /** The format used for the imaginary part. */
049        private NumberFormat imaginaryFormat;
050    
051        /** The format used for the real part. */
052        private NumberFormat realFormat;
053        
054        /**
055         * Create an instance with the default imaginary character, 'i', and the
056         * default number format for both real and imaginary parts.
057         */
058        public ComplexFormat() {
059            this(DEFAULT_IMAGINARY_CHARACTER, getDefaultNumberFormat());
060        }
061    
062        /**
063         * Create an instance with a custom number format for both real and
064         * imaginary parts.
065         * @param format the custom format for both real and imaginary parts.
066         */
067        public ComplexFormat(NumberFormat format) {
068            this(DEFAULT_IMAGINARY_CHARACTER, format);
069        }
070        
071        /**
072         * Create an instance with a custom number format for the real part and a
073         * custom number format for the imaginary part.
074         * @param realFormat the custom format for the real part.
075         * @param imaginaryFormat the custom format for the imaginary part.
076         */
077        public ComplexFormat(NumberFormat realFormat, NumberFormat imaginaryFormat) {
078            this(DEFAULT_IMAGINARY_CHARACTER, realFormat, imaginaryFormat);
079        }
080        
081        /**
082         * Create an instance with a custom imaginary character, and the default
083         * number format for both real and imaginary parts.
084         * @param imaginaryCharacter The custom imaginary character.
085         */
086        public ComplexFormat(String imaginaryCharacter) {
087            this(imaginaryCharacter, getDefaultNumberFormat());
088        }
089        
090        /**
091         * Create an instance with a custom imaginary character, and a custom number
092         * format for both real and imaginary parts.
093         * @param imaginaryCharacter The custom imaginary character.
094         * @param format the custom format for both real and imaginary parts.
095         */
096        public ComplexFormat(String imaginaryCharacter, NumberFormat format) {
097            this(imaginaryCharacter, format, (NumberFormat)format.clone());
098        }
099        
100        /**
101         * Create an instance with a custom imaginary character, a custom number
102         * format for the real part, and a custom number format for the imaginary
103         * part.
104         * @param imaginaryCharacter The custom imaginary character.
105         * @param realFormat the custom format for the real part.
106         * @param imaginaryFormat the custom format for the imaginary part.
107         */
108        public ComplexFormat(String imaginaryCharacter, NumberFormat realFormat,
109                NumberFormat imaginaryFormat) {
110            super();
111            setImaginaryCharacter(imaginaryCharacter);
112            setImaginaryFormat(imaginaryFormat);
113            setRealFormat(realFormat);
114        }
115    
116        /**
117         * Get the set of locales for which complex formats are available.
118         * <p>This is the same set as the {@link NumberFormat} set.</p> 
119         * @return available complex format locales.
120         */
121        public static Locale[] getAvailableLocales() {
122            return NumberFormat.getAvailableLocales();
123        }
124    
125        /**
126         * This static method calls {@link #format(Object)} on a default instance of
127         * ComplexFormat.
128         *
129         * @param c Complex object to format
130         * @return A formatted number in the form "Re(c) + Im(c)i"
131         */
132        public static String formatComplex(Complex c) {
133            return getInstance().format(c);
134        }
135        
136        /**
137         * Formats a {@link Complex} object to produce a string.
138         *
139         * @param complex the object to format.
140         * @param toAppendTo where the text is to be appended
141         * @param pos On input: an alignment field, if desired. On output: the
142         *            offsets of the alignment field
143         * @return the value passed in as toAppendTo.
144         */
145        public StringBuffer format(Complex complex, StringBuffer toAppendTo,
146                FieldPosition pos) {
147            
148            pos.setBeginIndex(0);
149            pos.setEndIndex(0);
150    
151            // format real
152            double re = complex.getReal();
153            formatDouble(re, getRealFormat(), toAppendTo, pos);
154            
155            // format sign and imaginary
156            double im = complex.getImaginary();
157            if (im < 0.0) {
158                toAppendTo.append(" - ");
159                formatDouble(-im, getImaginaryFormat(), toAppendTo, pos);
160                toAppendTo.append(getImaginaryCharacter());
161            } else if (im > 0.0 || Double.isNaN(im)) {
162                toAppendTo.append(" + ");
163                formatDouble(im, getImaginaryFormat(), toAppendTo, pos);
164                toAppendTo.append(getImaginaryCharacter());
165            }
166            
167            return toAppendTo;
168        }
169        
170        /**
171         * Formats a object to produce a string.  <code>obj</code> must be either a 
172         * {@link Complex} object or a {@link Number} object.  Any other type of
173         * object will result in an {@link IllegalArgumentException} being thrown.
174         *
175         * @param obj the object to format.
176         * @param toAppendTo where the text is to be appended
177         * @param pos On input: an alignment field, if desired. On output: the
178         *            offsets of the alignment field
179         * @return the value passed in as toAppendTo.
180         * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
181         * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
182         */
183        @Override
184        public StringBuffer format(Object obj, StringBuffer toAppendTo,
185                FieldPosition pos) {
186            
187            StringBuffer ret = null;
188            
189            if (obj instanceof Complex) {
190                ret = format( (Complex)obj, toAppendTo, pos);
191            } else if (obj instanceof Number) {
192                ret = format( new Complex(((Number)obj).doubleValue(), 0.0),
193                    toAppendTo, pos);
194            } else { 
195                throw MathRuntimeException.createIllegalArgumentException(
196                      "cannot format a {0} instance as a complex number",
197                      obj.getClass().getName());
198            }
199            
200            return ret;
201        }
202    
203        /**
204         * Access the imaginaryCharacter.
205         * @return the imaginaryCharacter.
206         */
207        public String getImaginaryCharacter() {
208            return imaginaryCharacter;
209        }
210        
211        /**
212         * Access the imaginaryFormat.
213         * @return the imaginaryFormat.
214         */
215        public NumberFormat getImaginaryFormat() {
216            return imaginaryFormat;
217        }
218        
219        /**
220         * Returns the default complex format for the current locale.
221         * @return the default complex format.
222         */
223        public static ComplexFormat getInstance() {
224            return getInstance(Locale.getDefault());
225        }
226        
227        /**
228         * Returns the default complex format for the given locale.
229         * @param locale the specific locale used by the format.
230         * @return the complex format specific to the given locale.
231         */
232        public static ComplexFormat getInstance(Locale locale) {
233            NumberFormat f = getDefaultNumberFormat(locale);
234            return new ComplexFormat(f);
235        }
236        
237        /**
238         * Access the realFormat.
239         * @return the realFormat.
240         */
241        public NumberFormat getRealFormat() {
242            return realFormat;
243        }
244    
245        /**
246         * Parses a string to produce a {@link Complex} object.
247         *
248         * @param source the string to parse
249         * @return the parsed {@link Complex} object.
250         * @exception ParseException if the beginning of the specified string
251         *            cannot be parsed.
252         */
253        public Complex parse(String source) throws ParseException {
254            ParsePosition parsePosition = new ParsePosition(0);
255            Complex result = parse(source, parsePosition);
256            if (parsePosition.getIndex() == 0) {
257                throw MathRuntimeException.createParseException(
258                        parsePosition.getErrorIndex(),
259                        "unparseable complex number: \"{0}\"", source);
260            }
261            return result;
262        }
263        
264        /**
265         * Parses a string to produce a {@link Complex} object.
266         *
267         * @param source the string to parse
268         * @param pos input/ouput parsing parameter.
269         * @return the parsed {@link Complex} object.
270         */
271        public Complex parse(String source, ParsePosition pos) {
272            int initialIndex = pos.getIndex();
273    
274            // parse whitespace
275            parseAndIgnoreWhitespace(source, pos);
276    
277            // parse real
278            Number re = parseNumber(source, getRealFormat(), pos);
279            if (re == null) {
280                // invalid real number
281                // set index back to initial, error index should already be set
282                pos.setIndex(initialIndex);
283                return null;
284            }
285    
286            // parse sign
287            int startIndex = pos.getIndex();
288            char c = parseNextCharacter(source, pos);
289            int sign = 0;
290            switch (c) {
291            case 0 :
292                // no sign
293                // return real only complex number
294                return new Complex(re.doubleValue(), 0.0);
295            case '-' :
296                sign = -1;
297                break;
298            case '+' :
299                sign = 1;
300                break;
301            default :
302                // invalid sign
303                // set index back to initial, error index should be the last
304                // character examined.
305                pos.setIndex(initialIndex);
306                pos.setErrorIndex(startIndex);
307                return null;
308            }
309    
310            // parse whitespace
311            parseAndIgnoreWhitespace(source, pos);
312    
313            // parse imaginary
314            Number im = parseNumber(source, getRealFormat(), pos);
315            if (im == null) {
316                // invalid imaginary number
317                // set index back to initial, error index should already be set
318                pos.setIndex(initialIndex);
319                return null;
320            }
321    
322            // parse imaginary character
323            if (!parseFixedstring(source, getImaginaryCharacter(), pos)) {
324                return null;
325            }
326    
327            return new Complex(re.doubleValue(), im.doubleValue() * sign);
328    
329        }
330         
331        /**
332         * Parses a string to produce a object.
333         *
334         * @param source the string to parse
335         * @param pos input/ouput parsing parameter.
336         * @return the parsed object.
337         * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
338         */
339        @Override
340        public Object parseObject(String source, ParsePosition pos) {
341            return parse(source, pos);
342        }
343    
344        /**
345         * Modify the imaginaryCharacter.
346         * @param imaginaryCharacter The new imaginaryCharacter value.
347         * @throws IllegalArgumentException if <code>imaginaryCharacter</code> is
348         *         <code>null</code> or an empty string.
349         */
350        public void setImaginaryCharacter(String imaginaryCharacter) {
351            if (imaginaryCharacter == null || imaginaryCharacter.length() == 0) {
352                throw MathRuntimeException.createIllegalArgumentException(
353                      "empty string for imaginary character");
354            }
355            this.imaginaryCharacter = imaginaryCharacter;
356        }
357        
358        /**
359         * Modify the imaginaryFormat.
360         * @param imaginaryFormat The new imaginaryFormat value.
361         * @throws IllegalArgumentException if <code>imaginaryFormat</code> is
362         *         <code>null</code>.
363         */
364        public void setImaginaryFormat(NumberFormat imaginaryFormat) {
365            if (imaginaryFormat == null) {
366                throw MathRuntimeException.createIllegalArgumentException(
367                      "null imaginary format");
368            }
369            this.imaginaryFormat = imaginaryFormat;
370        }
371        
372        /**
373         * Modify the realFormat.
374         * @param realFormat The new realFormat value.
375         * @throws IllegalArgumentException if <code>realFormat</code> is
376         *         <code>null</code>.
377         */
378        public void setRealFormat(NumberFormat realFormat) {
379            if (realFormat == null) {
380                throw MathRuntimeException.createIllegalArgumentException(
381                      "null real format");
382            }
383            this.realFormat = realFormat;
384        }
385    
386    }