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
18 package org.apache.commons.math.complex;
19
20 import java.io.Serializable;
21 import java.text.FieldPosition;
22 import java.text.Format;
23 import java.text.NumberFormat;
24 import java.text.ParseException;
25 import java.text.ParsePosition;
26 import java.util.Locale;
27
28 /**
29 * Formats a Complex number in cartesian format "Re(c) + Im(c)i". 'i' can
30 * be replaced with 'j', and the number format for both real and imaginary parts
31 * can be configured.
32 *
33 * @author Apache Software Foundation
34 * @version $Revision: 480440 $ $Date: 2006-11-29 00:14:12 -0700 (Wed, 29 Nov 2006) $
35 */
36 public class ComplexFormat extends Format implements Serializable {
37
38 /** Serializable version identifier */
39 private static final long serialVersionUID = -6337346779577272306L;
40
41 /** The default imaginary character. */
42 private static final String DEFAULT_IMAGINARY_CHARACTER = "i";
43
44 /** The notation used to signify the imaginary part of the complex number. */
45 private String imaginaryCharacter;
46
47 /** The format used for the imaginary part. */
48 private NumberFormat imaginaryFormat;
49
50 /** The format used for the real part. */
51 private NumberFormat realFormat;
52
53 /**
54 * Create an instance with the default imaginary character, 'i', and the
55 * default number format for both real and imaginary parts.
56 */
57 public ComplexFormat() {
58 this(DEFAULT_IMAGINARY_CHARACTER, getDefaultNumberFormat());
59 }
60
61 /**
62 * Create an instance with a custom number format for both real and
63 * imaginary parts.
64 * @param format the custom format for both real and imaginary parts.
65 */
66 public ComplexFormat(NumberFormat format) {
67 this(DEFAULT_IMAGINARY_CHARACTER, format);
68 }
69
70 /**
71 * Create an instance with a custom number format for the real part and a
72 * custom number format for the imaginary part.
73 * @param realFormat the custom format for the real part.
74 * @param imaginaryFormat the custom format for the imaginary part.
75 */
76 public ComplexFormat(NumberFormat realFormat,
77 NumberFormat imaginaryFormat) {
78 this(DEFAULT_IMAGINARY_CHARACTER, realFormat, imaginaryFormat);
79 }
80
81 /**
82 * Create an instance with a custom imaginary character, and the default
83 * number format for both real and imaginary parts.
84 * @param imaginaryCharacter The custom imaginary character.
85 */
86 public ComplexFormat(String imaginaryCharacter) {
87 this(imaginaryCharacter, getDefaultNumberFormat());
88 }
89
90 /**
91 * Create an instance with a custom imaginary character, and a custom number
92 * format for both real and imaginary parts.
93 * @param imaginaryCharacter The custom imaginary character.
94 * @param format the custom format for both real and imaginary parts.
95 */
96 public ComplexFormat(String imaginaryCharacter, NumberFormat format) {
97 this(imaginaryCharacter, format, (NumberFormat)format.clone());
98 }
99
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 * This static method calls formatComplex() on a default instance of
118 * ComplexFormat.
119 *
120 * @param c Complex object to format
121 * @return A formatted number in the form "Re(c) + Im(c)i"
122 */
123 public static String formatComplex( Complex c ) {
124 return getInstance().format( c );
125 }
126
127 /**
128 * Formats a {@link Complex} object to produce a string.
129 *
130 * @param complex the object to format.
131 * @param toAppendTo where the text is to be appended
132 * @param pos On input: an alignment field, if desired. On output: the
133 * offsets of the alignment field
134 * @return the value passed in as toAppendTo.
135 */
136 public StringBuffer format(Complex complex, StringBuffer toAppendTo,
137 FieldPosition pos) {
138
139 pos.setBeginIndex(0);
140 pos.setEndIndex(0);
141
142 // format real
143 double re = complex.getReal();
144 formatDouble(re, getRealFormat(), toAppendTo, pos);
145
146 // format sign and imaginary
147 double im = complex.getImaginary();
148 if (im < 0.0) {
149 toAppendTo.append(" - ");
150 formatDouble(-im, getImaginaryFormat(), toAppendTo, pos);
151 toAppendTo.append(getImaginaryCharacter());
152 } else if (im > 0.0 || Double.isNaN(im)) {
153 toAppendTo.append(" + ");
154 formatDouble(im, getImaginaryFormat(), toAppendTo, pos);
155 toAppendTo.append(getImaginaryCharacter());
156 }
157
158 return toAppendTo;
159 }
160
161 /**
162 * Formats a object to produce a string. <code>obj</code> must be either a
163 * {@link Complex} object or a {@link Number} object. Any other type of
164 * object will result in an {@link IllegalArgumentException} being thrown.
165 *
166 * @param obj the object to format.
167 * @param toAppendTo where the text is to be appended
168 * @param pos On input: an alignment field, if desired. On output: the
169 * offsets of the alignment field
170 * @return the value passed in as toAppendTo.
171 * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
172 * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
173 */
174 public StringBuffer format(Object obj, StringBuffer toAppendTo,
175 FieldPosition pos) {
176
177 StringBuffer ret = null;
178
179 if (obj instanceof Complex) {
180 ret = format( (Complex)obj, toAppendTo, pos);
181 } else if (obj instanceof Number) {
182 ret = format( new Complex(((Number)obj).doubleValue(), 0.0),
183 toAppendTo, pos);
184 } else {
185 throw new IllegalArgumentException(
186 "Cannot format given Object as a Date");
187 }
188
189 return ret;
190 }
191
192 /**
193 * Formats a double value to produce a string. In general, the value is
194 * formatted using the formatting rules of <code>format</code>. There are
195 * three exceptions to this:
196 * <ol>
197 * <li>NaN is formatted as '(NaN)'</li>
198 * <li>Positive infinity is formatted as '(Infinity)'</li>
199 * <li>Negative infinity is formatted as '(-Infinity)'</li>
200 * </ol>
201 *
202 * @param value the double to format.
203 * @param format the format used.
204 * @param toAppendTo where the text is to be appended
205 * @param pos On input: an alignment field, if desired. On output: the
206 * offsets of the alignment field
207 * @return the value passed in as toAppendTo.
208 */
209 private StringBuffer formatDouble(double value, NumberFormat format,
210 StringBuffer toAppendTo, FieldPosition pos) {
211 if( Double.isNaN(value) || Double.isInfinite(value) ) {
212 toAppendTo.append('(');
213 toAppendTo.append(value);
214 toAppendTo.append(')');
215 } else {
216 format.format(value, toAppendTo, pos);
217 }
218 return toAppendTo;
219 }
220
221 /**
222 * Get the set of locales for which complex formats are available. This
223 * is the same set as the {@link NumberFormat} set.
224 * @return available complex format locales.
225 */
226 public static Locale[] getAvailableLocales() {
227 return NumberFormat.getAvailableLocales();
228 }
229
230 /**
231 * Create a default number format. The default number format is based on
232 * {@link NumberFormat#getInstance()} with the only customizing is the
233 * maximum number of fraction digits, which is set to 2.
234 * @return the default number format.
235 */
236 private static NumberFormat getDefaultNumberFormat() {
237 return getDefaultNumberFormat(Locale.getDefault());
238 }
239
240 /**
241 * Create a default number format. The default number format is based on
242 * {@link NumberFormat#getInstance(java.util.Locale)} with the only
243 * customizing is the maximum number of fraction digits, which is set to 2.
244 * @param locale the specific locale used by the format.
245 * @return the default number format specific to the given locale.
246 */
247 private static NumberFormat getDefaultNumberFormat(Locale locale) {
248 NumberFormat nf = NumberFormat.getInstance(locale);
249 nf.setMaximumFractionDigits(2);
250 return nf;
251 }
252
253 /**
254 * Access the imaginaryCharacter.
255 * @return the imaginaryCharacter.
256 */
257 public String getImaginaryCharacter() {
258 return imaginaryCharacter;
259 }
260
261 /**
262 * Access the imaginaryFormat.
263 * @return the imaginaryFormat.
264 */
265 public NumberFormat getImaginaryFormat() {
266 return imaginaryFormat;
267 }
268
269 /**
270 * Returns the default complex format for the current locale.
271 * @return the default complex format.
272 */
273 public static ComplexFormat getInstance() {
274 return getInstance(Locale.getDefault());
275 }
276
277 /**
278 * Returns the default complex format for the given locale.
279 * @param locale the specific locale used by the format.
280 * @return the complex format specific to the given locale.
281 */
282 public static ComplexFormat getInstance(Locale locale) {
283 NumberFormat f = getDefaultNumberFormat(locale);
284 return new ComplexFormat(f);
285 }
286
287 /**
288 * Access the realFormat.
289 * @return the realFormat.
290 */
291 public NumberFormat getRealFormat() {
292 return realFormat;
293 }
294
295 /**
296 * Parses a string to produce a {@link Complex} object.
297 *
298 * @param source the string to parse
299 * @return the parsed {@link Complex} object.
300 * @exception ParseException if the beginning of the specified string
301 * cannot be parsed.
302 */
303 public Complex parse(String source) throws ParseException {
304 ParsePosition parsePosition = new ParsePosition(0);
305 Complex result = parse(source, parsePosition);
306 if (parsePosition.getIndex() == 0) {
307 throw new ParseException("Unparseable complex number: \"" + source +
308 "\"", parsePosition.getErrorIndex());
309 }
310 return result;
311 }
312
313 /**
314 * Parses a string to produce a {@link Complex} object.
315 *
316 * @param source the string to parse
317 * @param pos input/ouput parsing parameter.
318 * @return the parsed {@link Complex} object.
319 */
320 public Complex parse(String source, ParsePosition pos) {
321 int initialIndex = pos.getIndex();
322
323 // parse whitespace
324 parseAndIgnoreWhitespace(source, pos);
325
326 // parse real
327 Number re = parseNumber(source, getRealFormat(), pos);
328 if (re == null) {
329 // invalid real number
330 // set index back to initial, error index should already be set
331 // character examined.
332 pos.setIndex(initialIndex);
333 return null;
334 }
335
336 // parse sign
337 int startIndex = pos.getIndex();
338 char c = parseNextCharacter(source, pos);
339 int sign = 0;
340 switch (c) {
341 case 0 :
342 // no sign
343 // return real only complex number
344 return new Complex(re.doubleValue(), 0.0);
345 case '-' :
346 sign = -1;
347 break;
348 case '+' :
349 sign = 1;
350 break;
351 default :
352 // invalid sign
353 // set index back to initial, error index should be the last
354 // character examined.
355 pos.setIndex(initialIndex);
356 pos.setErrorIndex(startIndex);
357 return null;
358 }
359
360 // parse whitespace
361 parseAndIgnoreWhitespace(source, pos);
362
363 // parse imaginary
364 Number im = parseNumber(source, getRealFormat(), pos);
365 if (im == null) {
366 // invalid imaginary number
367 // set index back to initial, error index should already be set
368 // character examined.
369 pos.setIndex(initialIndex);
370 return null;
371 }
372
373 // parse imaginary character
374 int n = getImaginaryCharacter().length();
375 startIndex = pos.getIndex();
376 int endIndex = startIndex + n;
377 if (source.substring(startIndex, endIndex).compareTo(
378 getImaginaryCharacter()) != 0) {
379 // set index back to initial, error index should be the start index
380 // character examined.
381 pos.setIndex(initialIndex);
382 pos.setErrorIndex(startIndex);
383 return null;
384 }
385 pos.setIndex(endIndex);
386
387 return new Complex(re.doubleValue(), im.doubleValue() * sign);
388 }
389
390 /**
391 * Parses <code>source</code> until a non-whitespace character is found.
392 *
393 * @param source the string to parse
394 * @param pos input/ouput parsing parameter. On output, <code>pos</code>
395 * holds the index of the next non-whitespace character.
396 */
397 private void parseAndIgnoreWhitespace(String source, ParsePosition pos) {
398 parseNextCharacter(source, pos);
399 pos.setIndex(pos.getIndex() - 1);
400 }
401
402 /**
403 * Parses <code>source</code> until a non-whitespace character is found.
404 *
405 * @param source the string to parse
406 * @param pos input/ouput parsing parameter.
407 * @return the first non-whitespace character.
408 */
409 private char parseNextCharacter(String source, ParsePosition pos) {
410 int index = pos.getIndex();
411 int n = source.length();
412 char ret = 0;
413
414 if (index < n) {
415 char c;
416 do {
417 c = source.charAt(index++);
418 } while (Character.isWhitespace(c) && index < n);
419 pos.setIndex(index);
420
421 if (index < n) {
422 ret = c;
423 }
424 }
425
426 return ret;
427 }
428
429 /**
430 * Parses <code>source</code> for a special double values. These values
431 * include Double.NaN, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY.
432 *
433 * @param source the string to parse
434 * @param value the special value to parse.
435 * @param pos input/ouput parsing parameter.
436 * @return the special number.
437 */
438 private Number parseNumber(String source, double value, ParsePosition pos) {
439 Number ret = null;
440
441 StringBuffer sb = new StringBuffer();
442 sb.append('(');
443 sb.append(value);
444 sb.append(')');
445
446 int n = sb.length();
447 int startIndex = pos.getIndex();
448 int endIndex = startIndex + n;
449 if (endIndex < source.length()) {
450 if (source.substring(startIndex, endIndex).compareTo(sb.toString()) == 0) {
451 ret = new Double(value);
452 pos.setIndex(endIndex);
453 }
454 }
455
456 return ret;
457 }
458
459 /**
460 * Parses <code>source</code> for a number. This method can parse normal,
461 * numeric values as well as special values. These special values include
462 * Double.NaN, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY.
463 *
464 * @param source the string to parse
465 * @param format the number format used to parse normal, numeric values.
466 * @param pos input/ouput parsing parameter.
467 * @return the parsed number.
468 */
469 private Number parseNumber(String source, NumberFormat format, ParsePosition pos) {
470 int startIndex = pos.getIndex();
471 Number number = format.parse(source, pos);
472 int endIndex = pos.getIndex();
473
474 // check for error parsing number
475 if (startIndex == endIndex) {
476 // try parsing special numbers
477 double[] special = {Double.NaN, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY};
478 for (int i = 0; i < special.length; ++i) {
479 number = parseNumber(source, special[i], pos);
480 if (number != null) {
481 break;
482 }
483 }
484 }
485
486 return number;
487 }
488
489 /**
490 * Parses a string to produce a object.
491 *
492 * @param source the string to parse
493 * @param pos input/ouput parsing parameter.
494 * @return the parsed object.
495 * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
496 */
497 public Object parseObject(String source, ParsePosition pos) {
498 return parse(source, pos);
499 }
500 /**
501 * Modify the imaginaryCharacter.
502 * @param imaginaryCharacter The new imaginaryCharacter value.
503 * @throws IllegalArgumentException if <code>imaginaryCharacter</code> is
504 * <code>null</code> or an empty string.
505 */
506 public void setImaginaryCharacter(String imaginaryCharacter) {
507 if (imaginaryCharacter == null || imaginaryCharacter.length() == 0) {
508 throw new IllegalArgumentException(
509 "imaginaryCharacter must be a non-empty string.");
510 }
511 this.imaginaryCharacter = imaginaryCharacter;
512 }
513
514 /**
515 * Modify the imaginaryFormat.
516 * @param imaginaryFormat The new imaginaryFormat value.
517 * @throws IllegalArgumentException if <code>imaginaryFormat</code> is
518 * <code>null</code>.
519 */
520 public void setImaginaryFormat(NumberFormat imaginaryFormat) {
521 if (imaginaryFormat == null) {
522 throw new IllegalArgumentException(
523 "imaginaryFormat can not be null.");
524 }
525 this.imaginaryFormat = imaginaryFormat;
526 }
527
528 /**
529 * Modify the realFormat.
530 * @param realFormat The new realFormat value.
531 * @throws IllegalArgumentException if <code>realFormat</code> is
532 * <code>null</code>.
533 */
534 public void setRealFormat(NumberFormat realFormat) {
535 if (realFormat == null) {
536 throw new IllegalArgumentException(
537 "realFormat can not be null.");
538 }
539 this.realFormat = realFormat;
540 }
541 }