1 /*
2 * Copyright (c) 1996, 2006, 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, 1997 - All Rights Reserved
28 * (C) Copyright IBM Corp. 1996 - 1998 - 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
39 package java.text;
40
41 import java.math.BigDecimal;
42 import java.math.BigInteger;
43 import java.math.RoundingMode;
44
45 /**
46 * Digit List. Private to DecimalFormat.
47 * Handles the transcoding
48 * between numeric values and strings of characters. Only handles
49 * non-negative numbers. The division of labor between DigitList and
50 * DecimalFormat is that DigitList handles the radix 10 representation
51 * issues; DecimalFormat handles the locale-specific issues such as
52 * positive/negative, grouping, decimal point, currency, and so on.
53 *
54 * A DigitList is really a representation of a floating point value.
55 * It may be an integer value; we assume that a double has sufficient
56 * precision to represent all digits of a long.
57 *
58 * The DigitList representation consists of a string of characters,
59 * which are the digits radix 10, from '0' to '9'. It also has a radix
60 * 10 exponent associated with it. The value represented by a DigitList
61 * object can be computed by mulitplying the fraction f, where 0 <= f < 1,
62 * derived by placing all the digits of the list to the right of the
63 * decimal point, by 10^exponent.
64 *
65 * @see Locale
66 * @see Format
67 * @see NumberFormat
68 * @see DecimalFormat
69 * @see ChoiceFormat
70 * @see MessageFormat
71 * @author Mark Davis, Alan Liu
72 */
73 final class DigitList implements Cloneable {
74 /**
75 * The maximum number of significant digits in an IEEE 754 double, that
76 * is, in a Java double. This must not be increased, or garbage digits
77 * will be generated, and should not be decreased, or accuracy will be lost.
78 */
79 public static final int MAX_COUNT = 19; // == Long.toString(Long.MAX_VALUE).length()
80
81 /**
82 * These data members are intentionally public and can be set directly.
83 *
84 * The value represented is given by placing the decimal point before
85 * digits[decimalAt]. If decimalAt is < 0, then leading zeros between
86 * the decimal point and the first nonzero digit are implied. If decimalAt
87 * is > count, then trailing zeros between the digits[count-1] and the
88 * decimal point are implied.
89 *
90 * Equivalently, the represented value is given by f * 10^decimalAt. Here
91 * f is a value 0.1 <= f < 1 arrived at by placing the digits in Digits to
92 * the right of the decimal.
93 *
94 * DigitList is normalized, so if it is non-zero, figits[0] is non-zero. We
95 * don't allow denormalized numbers because our exponent is effectively of
96 * unlimited magnitude. The count value contains the number of significant
97 * digits present in digits[].
98 *
99 * Zero is represented by any DigitList with count == 0 or with each digits[i]
100 * for all i <= count == '0'.
101 */
102 public int decimalAt = 0;
103 public int count = 0;
104 public char[] digits = new char[MAX_COUNT];
105
106 private char[] data;
107 private RoundingMode roundingMode = RoundingMode.HALF_EVEN;
108 private boolean isNegative = false;
109
110 /**
111 * Return true if the represented number is zero.
112 */
113 boolean isZero() {
114 for (int i=0; i < count; ++i) {
115 if (digits[i] != '0') {
116 return false;
117 }
118 }
119 return true;
120 }
121
122 /**
123 * Set the rounding mode
124 */
125 void setRoundingMode(RoundingMode r) {
126 roundingMode = r;
127 }
128
129 /**
130 * Clears out the digits.
131 * Use before appending them.
132 * Typically, you set a series of digits with append, then at the point
133 * you hit the decimal point, you set myDigitList.decimalAt = myDigitList.count;
134 * then go on appending digits.
135 */
136 public void clear () {
137 decimalAt = 0;
138 count = 0;
139 }
140
141 /**
142 * Appends a digit to the list, extending the list when necessary.
143 */
144 public void append(char digit) {
145 if (count == digits.length) {
146 char[] data = new char[count + 100];
147 System.arraycopy(digits, 0, data, 0, count);
148 digits = data;
149 }
150 digits[count++] = digit;
151 }
152
153 /**
154 * Utility routine to get the value of the digit list
155 * If (count == 0) this throws a NumberFormatException, which
156 * mimics Long.parseLong().
157 */
158 public final double getDouble() {
159 if (count == 0) {
160 return 0.0;
161 }
162
163 StringBuffer temp = getStringBuffer();
164 temp.append('.');
165 temp.append(digits, 0, count);
166 temp.append('E');
167 temp.append(decimalAt);
168 return Double.parseDouble(temp.toString());
169 }
170
171 /**
172 * Utility routine to get the value of the digit list.
173 * If (count == 0) this returns 0, unlike Long.parseLong().
174 */
175 public final long getLong() {
176 // for now, simple implementation; later, do proper IEEE native stuff
177
178 if (count == 0) {
179 return 0;
180 }
181
182 // We have to check for this, because this is the one NEGATIVE value
183 // we represent. If we tried to just pass the digits off to parseLong,
184 // we'd get a parse failure.
185 if (isLongMIN_VALUE()) {
186 return Long.MIN_VALUE;
187 }
188
189 StringBuffer temp = getStringBuffer();
190 temp.append(digits, 0, count);
191 for (int i = count; i < decimalAt; ++i) {
192 temp.append('0');
193 }
194 return Long.parseLong(temp.toString());
195 }
196
197 public final BigDecimal getBigDecimal() {
198 if (count == 0) {
199 if (decimalAt == 0) {
200 return BigDecimal.ZERO;
201 } else {
202 return new BigDecimal("0E" + decimalAt);
203 }
204 }
205
206 if (decimalAt == count) {
207 return new BigDecimal(digits, 0, count);
208 } else {
209 return new BigDecimal(digits, 0, count).scaleByPowerOfTen(decimalAt - count);
210 }
211 }
212
213 /**
214 * Return true if the number represented by this object can fit into
215 * a long.
216 * @param isPositive true if this number should be regarded as positive
217 * @param ignoreNegativeZero true if -0 should be regarded as identical to
218 * +0; otherwise they are considered distinct
219 * @return true if this number fits into a Java long
220 */
221 boolean fitsIntoLong(boolean isPositive, boolean ignoreNegativeZero) {
222 // Figure out if the result will fit in a long. We have to
223 // first look for nonzero digits after the decimal point;
224 // then check the size. If the digit count is 18 or less, then
225 // the value can definitely be represented as a long. If it is 19
226 // then it may be too large.
227
228 // Trim trailing zeros. This does not change the represented value.
229 while (count > 0 && digits[count - 1] == '0') {
230 --count;
231 }
232
233 if (count == 0) {
234 // Positive zero fits into a long, but negative zero can only
235 // be represented as a double. - bug 4162852
236 return isPositive || ignoreNegativeZero;
237 }
238
239 if (decimalAt < count || decimalAt > MAX_COUNT) {
240 return false;
241 }
242
243 if (decimalAt < MAX_COUNT) return true;
244
245 // At this point we have decimalAt == count, and count == MAX_COUNT.
246 // The number will overflow if it is larger than 9223372036854775807
247 // or smaller than -9223372036854775808.
248 for (int i=0; i<count; ++i) {
249 char dig = digits[i], max = LONG_MIN_REP[i];
250 if (dig > max) return false;
251 if (dig < max) return true;
252 }
253
254 // At this point the first count digits match. If decimalAt is less
255 // than count, then the remaining digits are zero, and we return true.
256 if (count < decimalAt) return true;
257
258 // Now we have a representation of Long.MIN_VALUE, without the leading
259 // negative sign. If this represents a positive value, then it does
260 // not fit; otherwise it fits.
261 return !isPositive;
262 }
263
264 /**
265 * Set the digit list to a representation of the given double value.
266 * This method supports fixed-point notation.
267 * @param isNegative Boolean value indicating whether the number is negative.
268 * @param source Value to be converted; must not be Inf, -Inf, Nan,
269 * or a value <= 0.
270 * @param maximumFractionDigits The most fractional digits which should
271 * be converted.
272 */
273 public final void set(boolean isNegative, double source, int maximumFractionDigits) {
274 set(isNegative, source, maximumFractionDigits, true);
275 }
276
277 /**
278 * Set the digit list to a representation of the given double value.
279 * This method supports both fixed-point and exponential notation.
280 * @param isNegative Boolean value indicating whether the number is negative.
281 * @param source Value to be converted; must not be Inf, -Inf, Nan,
282 * or a value <= 0.
283 * @param maximumDigits The most fractional or total digits which should
284 * be converted.
285 * @param fixedPoint If true, then maximumDigits is the maximum
286 * fractional digits to be converted. If false, total digits.
287 */
288 final void set(boolean isNegative, double source, int maximumDigits, boolean fixedPoint) {
289 set(isNegative, Double.toString(source), maximumDigits, fixedPoint);
290 }
291
292 /**
293 * Generate a representation of the form DDDDD, DDDDD.DDDDD, or
294 * DDDDDE+/-DDDDD.
295 */
296 final void set(boolean isNegative, String s, int maximumDigits, boolean fixedPoint) {
297 this.isNegative = isNegative;
298 int len = s.length();
299 char[] source = getDataChars(len);
300 s.getChars(0, len, source, 0);
301
302 decimalAt = -1;
303 count = 0;
304 int exponent = 0;
305 // Number of zeros between decimal point and first non-zero digit after
306 // decimal point, for numbers < 1.
307 int leadingZerosAfterDecimal = 0;
308 boolean nonZeroDigitSeen = false;
309
310 for (int i = 0; i < len; ) {
311 char c = source[i++];
312 if (c == '.') {
313 decimalAt = count;
314 } else if (c == 'e' || c == 'E') {
315 exponent = parseInt(source, i, len);
316 break;
317 } else {
318 if (!nonZeroDigitSeen) {
319 nonZeroDigitSeen = (c != '0');
320 if (!nonZeroDigitSeen && decimalAt != -1)
321 ++leadingZerosAfterDecimal;
322 }
323 if (nonZeroDigitSeen) {
324 digits[count++] = c;
325 }
326 }
327 }
328 if (decimalAt == -1) {
329 decimalAt = count;
330 }
331 if (nonZeroDigitSeen) {
332 decimalAt += exponent - leadingZerosAfterDecimal;
333 }
334
335 if (fixedPoint) {
336 // The negative of the exponent represents the number of leading
337 // zeros between the decimal and the first non-zero digit, for
338 // a value < 0.1 (e.g., for 0.00123, -decimalAt == 2). If this
339 // is more than the maximum fraction digits, then we have an underflow
340 // for the printed representation.
341 if (-decimalAt > maximumDigits) {
342 // Handle an underflow to zero when we round something like
343 // 0.0009 to 2 fractional digits.
344 count = 0;
345 return;
346 } else if (-decimalAt == maximumDigits) {
347 // If we round 0.0009 to 3 fractional digits, then we have to
348 // create a new one digit in the least significant location.
349 if (shouldRoundUp(0)) {
350 count = 1;
351 ++decimalAt;
352 digits[0] = '1';
353 } else {
354 count = 0;
355 }
356 return;
357 }
358 // else fall through
359 }
360
361 // Eliminate trailing zeros.
362 while (count > 1 && digits[count - 1] == '0') {
363 --count;
364 }
365
366 // Eliminate digits beyond maximum digits to be displayed.
367 // Round up if appropriate.
368 round(fixedPoint ? (maximumDigits + decimalAt) : maximumDigits);
369 }
370
371 /**
372 * Round the representation to the given number of digits.
373 * @param maximumDigits The maximum number of digits to be shown.
374 * Upon return, count will be less than or equal to maximumDigits.
375 */
376 private final void round(int maximumDigits) {
377 // Eliminate digits beyond maximum digits to be displayed.
378 // Round up if appropriate.
379 if (maximumDigits >= 0 && maximumDigits < count) {
380 if (shouldRoundUp(maximumDigits)) {
381 // Rounding up involved incrementing digits from LSD to MSD.
382 // In most cases this is simple, but in a worst case situation
383 // (9999..99) we have to adjust the decimalAt value.
384 for (;;) {
385 --maximumDigits;
386 if (maximumDigits < 0) {
387 // We have all 9's, so we increment to a single digit
388 // of one and adjust the exponent.
389 digits[0] = '1';
390 ++decimalAt;
391 maximumDigits = 0; // Adjust the count
392 break;
393 }
394
395 ++digits[maximumDigits];
396 if (digits[maximumDigits] <= '9') break;
397 // digits[maximumDigits] = '0'; // Unnecessary since we'll truncate this
398 }
399 ++maximumDigits; // Increment for use as count
400 }
401 count = maximumDigits;
402
403 // Eliminate trailing zeros.
404 while (count > 1 && digits[count-1] == '0') {
405 --count;
406 }
407 }
408 }
409
410
411 /**
412 * Return true if truncating the representation to the given number
413 * of digits will result in an increment to the last digit. This
414 * method implements the rounding modes defined in the
415 * java.math.RoundingMode class.
416 * [bnf]
417 * @param maximumDigits the number of digits to keep, from 0 to
418 * <code>count-1</code>. If 0, then all digits are rounded away, and
419 * this method returns true if a one should be generated (e.g., formatting
420 * 0.09 with "#.#").
421 * @exception ArithmeticException if rounding is needed with rounding
422 * mode being set to RoundingMode.UNNECESSARY
423 * @return true if digit <code>maximumDigits-1</code> should be
424 * incremented
425 */
426 private boolean shouldRoundUp(int maximumDigits) {
427 if (maximumDigits < count) {
428 switch(roundingMode) {
429 case UP:
430 for (int i=maximumDigits; i<count; ++i) {
431 if (digits[i] != '0') {
432 return true;
433 }
434 }
435 break;
436 case DOWN:
437 break;
438 case CEILING:
439 for (int i=maximumDigits; i<count; ++i) {
440 if (digits[i] != '0') {
441 return !isNegative;
442 }
443 }
444 break;
445 case FLOOR:
446 for (int i=maximumDigits; i<count; ++i) {
447 if (digits[i] != '0') {
448 return isNegative;
449 }
450 }
451 break;
452 case HALF_UP:
453 if (digits[maximumDigits] >= '5') {
454 return true;
455 }
456 break;
457 case HALF_DOWN:
458 if (digits[maximumDigits] > '5') {
459 return true;
460 } else if (digits[maximumDigits] == '5' ) {
461 for (int i=maximumDigits+1; i<count; ++i) {
462 if (digits[i] != '0') {
463 return true;
464 }
465 }
466 }
467 break;
468 case HALF_EVEN:
469 // Implement IEEE half-even rounding
470 if (digits[maximumDigits] > '5') {
471 return true;
472 } else if (digits[maximumDigits] == '5' ) {
473 for (int i=maximumDigits+1; i<count; ++i) {
474 if (digits[i] != '0') {
475 return true;
476 }
477 }
478 return maximumDigits > 0 && (digits[maximumDigits-1] % 2 != 0);
479 }
480 break;
481 case UNNECESSARY:
482 for (int i=maximumDigits; i<count; ++i) {
483 if (digits[i] != '0') {
484 throw new ArithmeticException(
485 "Rounding needed with the rounding mode being set to RoundingMode.UNNECESSARY");
486 }
487 }
488 break;
489 default:
490 assert false;
491 }
492 }
493 return false;
494 }
495
496 /**
497 * Utility routine to set the value of the digit list from a long
498 */
499 public final void set(boolean isNegative, long source) {
500 set(isNegative, source, 0);
501 }
502
503 /**
504 * Set the digit list to a representation of the given long value.
505 * @param isNegative Boolean value indicating whether the number is negative.
506 * @param source Value to be converted; must be >= 0 or ==
507 * Long.MIN_VALUE.
508 * @param maximumDigits The most digits which should be converted.
509 * If maximumDigits is lower than the number of significant digits
510 * in source, the representation will be rounded. Ignored if <= 0.
511 */
512 public final void set(boolean isNegative, long source, int maximumDigits) {
513 this.isNegative = isNegative;
514
515 // This method does not expect a negative number. However,
516 // "source" can be a Long.MIN_VALUE (-9223372036854775808),
517 // if the number being formatted is a Long.MIN_VALUE. In that
518 // case, it will be formatted as -Long.MIN_VALUE, a number
519 // which is outside the legal range of a long, but which can
520 // be represented by DigitList.
521 if (source <= 0) {
522 if (source == Long.MIN_VALUE) {
523 decimalAt = count = MAX_COUNT;
524 System.arraycopy(LONG_MIN_REP, 0, digits, 0, count);
525 } else {
526 decimalAt = count = 0; // Values <= 0 format as zero
527 }
528 } else {
529 // Rewritten to improve performance. I used to call
530 // Long.toString(), which was about 4x slower than this code.
531 int left = MAX_COUNT;
532 int right;
533 while (source > 0) {
534 digits[--left] = (char)('0' + (source % 10));
535 source /= 10;
536 }
537 decimalAt = MAX_COUNT - left;
538 // Don't copy trailing zeros. We are guaranteed that there is at
539 // least one non-zero digit, so we don't have to check lower bounds.
540 for (right = MAX_COUNT - 1; digits[right] == '0'; --right)
541 ;
542 count = right - left + 1;
543 System.arraycopy(digits, left, digits, 0, count);
544 }
545 if (maximumDigits > 0) round(maximumDigits);
546 }
547
548 /**
549 * Set the digit list to a representation of the given BigDecimal value.
550 * This method supports both fixed-point and exponential notation.
551 * @param isNegative Boolean value indicating whether the number is negative.
552 * @param source Value to be converted; must not be a value <= 0.
553 * @param maximumDigits The most fractional or total digits which should
554 * be converted.
555 * @param fixedPoint If true, then maximumDigits is the maximum
556 * fractional digits to be converted. If false, total digits.
557 */
558 final void set(boolean isNegative, BigDecimal source, int maximumDigits, boolean fixedPoint) {
559 String s = source.toString();
560 extendDigits(s.length());
561
562 set(isNegative, s, maximumDigits, fixedPoint);
563 }
564
565 /**
566 * Set the digit list to a representation of the given BigInteger value.
567 * @param isNegative Boolean value indicating whether the number is negative.
568 * @param source Value to be converted; must be >= 0.
569 * @param maximumDigits The most digits which should be converted.
570 * If maximumDigits is lower than the number of significant digits
571 * in source, the representation will be rounded. Ignored if <= 0.
572 */
573 final void set(boolean isNegative, BigInteger source, int maximumDigits) {
574 this.isNegative = isNegative;
575 String s = source.toString();
576 int len = s.length();
577 extendDigits(len);
578 s.getChars(0, len, digits, 0);
579
580 decimalAt = len;
581 int right;
582 for (right = len - 1; right >= 0 && digits[right] == '0'; --right)
583 ;
584 count = right + 1;
585
586 if (maximumDigits > 0) {
587 round(maximumDigits);
588 }
589 }
590
591 /**
592 * equality test between two digit lists.
593 */
594 public boolean equals(Object obj) {
595 if (this == obj) // quick check
596 return true;
597 if (!(obj instanceof DigitList)) // (1) same object?
598 return false;
599 DigitList other = (DigitList) obj;
600 if (count != other.count ||
601 decimalAt != other.decimalAt)
602 return false;
603 for (int i = 0; i < count; i++)
604 if (digits[i] != other.digits[i])
605 return false;
606 return true;
607 }
608
609 /**
610 * Generates the hash code for the digit list.
611 */
612 public int hashCode() {
613 int hashcode = decimalAt;
614
615 for (int i = 0; i < count; i++) {
616 hashcode = hashcode * 37 + digits[i];
617 }
618
619 return hashcode;
620 }
621
622 /**
623 * Creates a copy of this object.
624 * @return a clone of this instance.
625 */
626 public Object clone() {
627 try {
628 DigitList other = (DigitList) super.clone();
629 char[] newDigits = new char[digits.length];
630 System.arraycopy(digits, 0, newDigits, 0, digits.length);
631 other.digits = newDigits;
632 other.tempBuffer = null;
633 return other;
634 } catch (CloneNotSupportedException e) {
635 throw new InternalError(e);
636 }
637 }
638
639 /**
640 * Returns true if this DigitList represents Long.MIN_VALUE;
641 * false, otherwise. This is required so that getLong() works.
642 */
643 private boolean isLongMIN_VALUE() {
644 if (decimalAt != count || count != MAX_COUNT) {
645 return false;
646 }
647
648 for (int i = 0; i < count; ++i) {
649 if (digits[i] != LONG_MIN_REP[i]) return false;
650 }
651
652 return true;
653 }
654
655 private static final int parseInt(char[] str, int offset, int strLen) {
656 char c;
657 boolean positive = true;
658 if ((c = str[offset]) == '-') {
659 positive = false;
660 offset++;
661 } else if (c == '+') {
662 offset++;
663 }
664
665 int value = 0;
666 while (offset < strLen) {
667 c = str[offset++];
668 if (c >= '0' && c <= '9') {
669 value = value * 10 + (c - '0');
670 } else {
671 break;
672 }
673 }
674 return positive ? value : -value;
675 }
676
677 // The digit part of -9223372036854775808L
678 private static final char[] LONG_MIN_REP = "9223372036854775808".toCharArray();
679
680 public String toString() {
681 if (isZero()) {
682 return "0";
683 }
684 StringBuffer buf = getStringBuffer();
685 buf.append("0.");
686 buf.append(digits, 0, count);
687 buf.append("x10^");
688 buf.append(decimalAt);
689 return buf.toString();
690 }
691
692 private StringBuffer tempBuffer;
693
694 private StringBuffer getStringBuffer() {
695 if (tempBuffer == null) {
696 tempBuffer = new StringBuffer(MAX_COUNT);
697 } else {
698 tempBuffer.setLength(0);
699 }
700 return tempBuffer;
701 }
702
703 private void extendDigits(int len) {
704 if (len > digits.length) {
705 digits = new char[len];
706 }
707 }
708
709 private final char[] getDataChars(int length) {
710 if (data == null || data.length < length) {
711 data = new char[length];
712 }
713 return data;
714 }
715 }