icuSources/i18n/digitlst.h

   1 /*
   2 ******************************************************************************
   3 *
   4 *   Copyright (C) 1997-2015, International Business Machines
   5 *   Corporation and others.  All Rights Reserved.
   6 *
   7 ******************************************************************************
   8 *
   9 * File DIGITLST.H
  10 *
  11 * Modification History:
  12 *
  13 *   Date        Name        Description
  14 *   02/25/97    aliu        Converted from java.
  15 *   03/21/97    clhuang     Updated per C++ implementation.
  16 *   04/15/97    aliu        Changed MAX_COUNT to DBL_DIG.  Changed Digit to char.
  17 *   09/09/97    aliu        Adapted for exponential notation support.
  18 *   08/02/98    stephen     Added nearest/even rounding
  19 *   06/29/99    stephen     Made LONG_DIGITS a macro to satisfy SUN compiler
  20 *   07/09/99    stephen     Removed kMaxCount (unused, for HP compiler)
  21 ******************************************************************************
  22 */
  23
  24 #ifndef DIGITLST_H
  25 #define DIGITLST_H
  26
  27 #include "unicode/uobject.h"
  28
  29 #if !UCONFIG_NO_FORMATTING
  30 #include "unicode/decimfmt.h"
  31 #include <float.h>
  32 #include "decContext.h"
  33 #include "decNumber.h"
  34 #include "cmemory.h"
  35
  36 // Decimal digits in a 64-bit int
  37 #define INT64_DIGITS 19
  38
  39 typedef enum EDigitListValues {
  40     MAX_DBL_DIGITS = DBL_DIG,
  41     MAX_I64_DIGITS = INT64_DIGITS,
  42     MAX_DIGITS = MAX_I64_DIGITS,
  43     MAX_EXPONENT = DBL_DIG,
  44     DIGIT_PADDING = 3,
  45     DEFAULT_DIGITS = 40,   // Initial storage size, will grow as needed.
  46
  47      // "+." + fDigits + "e" + fDecimalAt
  48     MAX_DEC_DIGITS = MAX_DIGITS + DIGIT_PADDING + MAX_EXPONENT
  49 } EDigitListValues;
  50
  51 U_NAMESPACE_BEGIN
  52
  53 class CharString;
  54 class DigitInterval;
  55
  56 // Export an explicit template instantiation of the MaybeStackHeaderAndArray that
  57 //    is used as a data member of DigitList.
  58 //
  59 //    MSVC requires this, even though it should not be necessary.
  60 //    No direct access to the MaybeStackHeaderAndArray leaks out of the i18n library.
  61 //
  62 //    Macintosh produces duplicate definition linker errors with the explicit template
  63 //    instantiation.
  64 //
  65 #if !U_PLATFORM_IS_DARWIN_BASED
  66 template class U_I18N_API MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>;
  67 #endif
  68
  69
  70 enum EStackMode { kOnStack };
  71
  72 enum EFastpathBits { kFastpathOk = 1, kNoDecimal = 2 };
  73
  74 /**
  75  * Digit List is actually a Decimal Floating Point number.
  76  * The original implementation has been replaced by a thin wrapper onto a
  77  * decimal number from the decNumber library.
  78  *
  79  * The original DigitList API has been retained, to minimize the impact of
  80  * the change on the rest of the ICU formatting code.
  81  *
  82  * The change to decNumber enables support for big decimal numbers, and
  83  * allows rounding computations to be done directly in decimal, avoiding
  84  * extra, and inaccurate, conversions to and from doubles.
  85  *
  86  * Original DigitList comments:
  87  *
  88  * Digit List utility class. Private to DecimalFormat.  Handles the transcoding
  89  * between numeric values and strings of characters.  Only handles
  90  * non-negative numbers.  The division of labor between DigitList and
  91  * DecimalFormat is that DigitList handles the radix 10 representation
  92  * issues; DecimalFormat handles the locale-specific issues such as
  93  * positive/negative, grouping, decimal point, currency, and so on.
  94  * <P>
  95  * A DigitList is really a representation of a floating point value.
  96  * It may be an integer value; we assume that a double has sufficient
  97  * precision to represent all digits of a long.
  98  * <P>
  99  * The DigitList representation consists of a string of characters,
 100  * which are the digits radix 10, from '0' to '9'.  It also has a radix
 101  * 10 exponent associated with it.  The value represented by a DigitList
 102  * object can be computed by mulitplying the fraction f, where 0 <= f < 1,
 103  * derived by placing all the digits of the list to the right of the
 104  * decimal point, by 10^exponent.
 105  *
 106  * --------
 107  *
 108  * DigitList vs. decimalNumber:
 109  *
 110  *    DigitList stores digits with the most significant first.
 111  *    decNumber stores digits with the least significant first.
 112  *
 113  *    DigitList, decimal point is before the most significant.
 114  *    decNumber, decimal point is after the least signficant digit.
 115  *
 116  *       digitList:    0.ddddd * 10 ^ exp
 117  *       decNumber:    ddddd. * 10 ^ exp
 118  *
 119  *       digitList exponent = decNumber exponent + digit count
 120  *
 121  *    digitList, digits are platform invariant chars, '0' - '9'
 122  *    decNumber, digits are binary, one per byte, 0 - 9.
 123  *
 124  *       (decNumber library is configurable in how digits are stored, ICU has configured
 125  *        it this way for convenience in replacing the old DigitList implementation.)
 126  */
 127 class U_I18N_API DigitList : public UMemory { // Declare external to make compiler happy
 128 public:
 129
 130     DigitList();
 131     ~DigitList();
 132
 133     /* copy constructor
 134      * @param DigitList The object to be copied.
 135      * @return the newly created object.
 136      */
 137     DigitList(const DigitList&); // copy constructor
 138
 139     /* assignment operator
 140      * @param DigitList The object to be copied.
 141      * @return the newly created object.
 142      */
 143     DigitList& operator=(const DigitList&);  // assignment operator
 144
 145     /**
 146      * Return true if another object is semantically equal to this one.
 147      * @param other The DigitList to be compared for equality
 148      * @return true if another object is semantically equal to this one.
 149      * return false otherwise.
 150      */
 151     UBool operator==(const DigitList& other) const;
 152
 153     int32_t  compare(const DigitList& other);
 154
 155
 156     inline UBool operator!=(const DigitList& other) const { return !operator==(other); }
 157
 158     /**
 159      * Clears out the digits.
 160      * Use before appending them.
 161      * Typically, you set a series of digits with append, then at the point
 162      * you hit the decimal point, you set myDigitList.fDecimalAt = myDigitList.fCount;
 163      * then go on appending digits.
 164      */
 165     void clear(void);
 166
 167     /**
 168      *  Remove, by rounding, any fractional part of the decimal number,
 169      *  leaving an integer value.
 170      */
 171     void toIntegralValue();
 172
 173     /**
 174      * Appends digits to the list.
 175      *    CAUTION:  this function is not recommended for new code.
 176      *              In the original DigitList implementation, decimal numbers were
 177      *              parsed by appending them to a digit list as they were encountered.
 178      *              With the revamped DigitList based on decNumber, append is very
 179      *              inefficient, and the interaction with the exponent value is confusing.
 180      *              Best avoided.
 181      *              TODO:  remove this function once all use has been replaced.
 182      *              TODO:  describe alternative to append()
 183      * @param digit The digit to be appended.
 184      */
 185     void append(char digit);
 186
 187     /**
 188      * Utility routine to get the value of the digit list
 189      * Returns 0.0 if zero length.
 190      * @return the value of the digit list.
 191      */
 192     double getDouble(void) const;
 193
 194     /**
 195      * Utility routine to get the value of the digit list
 196      * Make sure that fitsIntoLong() is called before calling this function.
 197      * Returns 0 if zero length.
 198      * @return the value of the digit list, return 0 if it is zero length
 199      */
 200     int32_t getLong(void) /*const*/;
 201
 202     /**
 203      * Utility routine to get the value of the digit list
 204      * Make sure that fitsIntoInt64() is called before calling this function.
 205      * Returns 0 if zero length.
 206      * @return the value of the digit list, return 0 if it is zero length
 207      */
 208     int64_t getInt64(void) /*const*/;
 209
 210     /**
 211      *  Utility routine to get the value of the digit list as a decimal string.
 212      */
 213     void getDecimal(CharString &str, UErrorCode &status);
 214
 215     /**
 216      * Return true if the number represented by this object can fit into
 217      * a long.
 218      * @param ignoreNegativeZero True if negative zero is ignored.
 219      * @return true if the number represented by this object can fit into
 220      * a long, return false otherwise.
 221      */
 222     UBool fitsIntoLong(UBool ignoreNegativeZero) /*const*/;
 223
 224     /**
 225      * Return true if the number represented by this object can fit into
 226      * an int64_t.
 227      * @param ignoreNegativeZero True if negative zero is ignored.
 228      * @return true if the number represented by this object can fit into
 229      * a long, return false otherwise.
 230      */
 231     UBool fitsIntoInt64(UBool ignoreNegativeZero) /*const*/;
 232
 233     /**
 234      * Utility routine to set the value of the digit list from a double.
 235      * @param source The value to be set
 236      */
 237     void set(double source);
 238
 239     /**
 240      * Utility routine to set the value of the digit list from a long.
 241      * If a non-zero maximumDigits is specified, no more than that number of
 242      * significant digits will be produced.
 243      * @param source The value to be set
 244      */
 245     void set(int32_t source);
 246
 247     /**
 248      * Utility routine to set the value of the digit list from an int64.
 249      * If a non-zero maximumDigits is specified, no more than that number of
 250      * significant digits will be produced.
 251      * @param source The value to be set
 252      */
 253     void set(int64_t source);
 254
 255     /**
 256      * Utility routine to set the value of the digit list from an int64.
 257      * Does not set the decnumber unless requested later
 258      * If a non-zero maximumDigits is specified, no more than that number of
 259      * significant digits will be produced.
 260      * @param source The value to be set
 261      */
 262     void setInteger(int64_t source);
 263
 264    /**
 265      * Utility routine to set the value of the digit list from a decimal number
 266      * string.
 267      * @param source The value to be set.  The string must be nul-terminated.
 268      * @param fastpathBits special flags for fast parsing
 269      */
 270     void set(const StringPiece &source, UErrorCode &status, uint32_t fastpathBits = 0);
 271
 272     /**
 273      * Multiply    this = this * arg
 274      *    This digitlist will be expanded if necessary to accomodate the result.
 275      *  @param arg  the number to multiply by.
 276      */
 277     void mult(const DigitList &arg, UErrorCode &status);
 278
 279     /**
 280      *   Divide    this = this / arg
 281      */
 282     void div(const DigitList &arg, UErrorCode &status);
 283
 284     //  The following functions replace direct access to the original DigitList implmentation
 285     //  data structures.
 286
 287     void setRoundingMode(DecimalFormat::ERoundingMode m);
 288
 289     /** Test a number for zero.
 290      * @return  TRUE if the number is zero
 291      */
 292     UBool isZero(void) const;
 293
 294     /** Test for a Nan
 295      * @return  TRUE if the number is a NaN
 296      */
 297     UBool isNaN(void) const {return decNumberIsNaN(fDecNumber);}
 298
 299     UBool isInfinite() const {return decNumberIsInfinite(fDecNumber);}
 300
 301     /**  Reduce, or normalize.  Removes trailing zeroes, adjusts exponent appropriately. */
 302     void     reduce();
 303
 304     /**  Remove trailing fraction zeros, adjust exponent accordingly. */
 305     void     trim();
 306
 307     /** Set to zero */
 308     void     setToZero() {uprv_decNumberZero(fDecNumber);}
 309
 310     /** get the number of digits in the decimal number */
 311     int32_t  digits() const {return fDecNumber->digits;}
 312
 313     /**
 314      * Round the number to the given number of digits.
 315      * @param maximumDigits The maximum number of digits to be shown.
 316      * Upon return, count will be less than or equal to maximumDigits.
 317      * result is guaranteed to be trimmed.
 318      */
 319     void round(int32_t maximumDigits);
 320
 321     void roundFixedPoint(int32_t maximumFractionDigits);
 322
 323     /** Ensure capacity for digits.  Grow the storage if it is currently less than
 324      *      the requested size.   Capacity is not reduced if it is already greater
 325      *      than requested.
 326      */
 327     void  ensureCapacity(int32_t  requestedSize, UErrorCode &status);
 328
 329     UBool    isPositive(void) const { return decNumberIsNegative(fDecNumber) == 0;}
 330     void     setPositive(UBool s);
 331
 332     void     setDecimalAt(int32_t d);
 333     int32_t  getDecimalAt();
 334
 335     void     setCount(int32_t c);
 336     int32_t  getCount() const;
 337
 338     /**
 339      * Set the digit in platform (invariant) format, from '0'..'9'
 340      * @param i index of digit
 341      * @param v digit value, from '0' to '9' in platform invariant format
 342      */
 343     void     setDigit(int32_t i, char v);
 344
 345     /**
 346      * Get the digit in platform (invariant) format, from '0'..'9' inclusive
 347      * @param i index of digit
 348      * @return invariant format of the digit
 349      */
 350     char     getDigit(int32_t i);
 351
 352
 353     /**
 354      * Get the digit's value, as an integer from 0..9 inclusive.
 355      * Note that internally this value is a decNumberUnit, but ICU configures it to be a uint8_t.
 356      * @param i index of digit
 357      * @return value of that digit
 358      */
 359     uint8_t     getDigitValue(int32_t i);
 360
 361     /**
 362      * Gets the upper bound exponent for this value. For 987, returns 3
 363      * because 10^3 is the smallest power of 10 that is just greater than
 364      * 987.
 365      */
 366     int32_t getUpperExponent() const;
 367
 368     /**
 369      * Gets the lower bound exponent for this value. For 98.7, returns -1
 370      * because the right most digit, is the 10^-1 place.
 371      */
 372     int32_t getLowerExponent() const { return fDecNumber->exponent; }
 373
 374     /**
 375      * Sets result to the smallest DigitInterval needed to display this
 376      * DigitList in fixed point form and returns result.
 377      */
 378     DigitInterval& getSmallestInterval(DigitInterval &result) const;
 379
 380     /**
 381      * Like getDigitValue, but the digit is identified by exponent.
 382      * For example, getDigitByExponent(7) returns the 10^7 place of this
 383      * DigitList. Unlike getDigitValue, there are no upper or lower bounds
 384      * for passed parameter. Instead, getDigitByExponent returns 0 if
 385      * the exponent falls outside the interval for this DigitList.
 386      */
 387     uint8_t getDigitByExponent(int32_t exponent) const;
 388
 389     /**
 390      * Appends the digits in this object to a CharString.
 391      * 3 is appended as (char) 3, not '3'
 392      */
 393     void appendDigitsTo(CharString &str, UErrorCode &status) const;
 394
 395     /**
 396      * Equivalent to roundFixedPoint(-digitExponent) except unlike
 397      * roundFixedPoint, this works for any digitExponent value.
 398      * If maxSigDigits is set then this instance is rounded to have no more
 399      * than maxSigDigits. The end result is guaranteed to be trimmed.
 400      */
 401     void roundAtExponent(int32_t digitExponent, int32_t maxSigDigits=INT32_MAX);
 402
 403     /**
 404      * Quantizes according to some amount and rounds according to the
 405      * context of this instance. Quantizing 3.233 with 0.05 gives 3.25.
 406      */
 407     void quantize(const DigitList &amount, UErrorCode &status);
 408
 409     /**
 410      * Like toScientific but only returns the exponent
 411      * leaving this instance unchanged.
 412      */
 413     int32_t getScientificExponent(
 414             int32_t minIntDigitCount, int32_t exponentMultiplier) const;
 415
 416     /**
 417      * Converts this instance to scientific notation. This instance
 418      * becomes the mantissa and the exponent is returned.
 419      * @param minIntDigitCount minimum integer digits in mantissa
 420      *   Exponent is set so that the actual number of integer digits
 421      *   in mantissa is as close to the minimum as possible.
 422      * @param exponentMultiplier The exponent is always a multiple of
 423      *  This number. Usually 1, but set to 3 for engineering notation.
 424      * @return exponent
 425      */
 426     int32_t toScientific(
 427             int32_t minIntDigitCount, int32_t exponentMultiplier);
 428
 429     /**
 430      * Shifts decimal to the right.
 431      */
 432     void shiftDecimalRight(int32_t numPlaces);
 433
 434 private:
 435     /*
 436      * These data members are intentionally public and can be set directly.
 437      *<P>
 438      * The value represented is given by placing the decimal point before
 439      * fDigits[fDecimalAt].  If fDecimalAt is < 0, then leading zeros between
 440      * the decimal point and the first nonzero digit are implied.  If fDecimalAt
 441      * is > fCount, then trailing zeros between the fDigits[fCount-1] and the
 442      * decimal point are implied.
 443      * <P>
 444      * Equivalently, the represented value is given by f * 10^fDecimalAt.  Here
 445      * f is a value 0.1 <= f < 1 arrived at by placing the digits in fDigits to
 446      * the right of the decimal.
 447      * <P>
 448      * DigitList is normalized, so if it is non-zero, fDigits[0] is non-zero.  We
 449      * don't allow denormalized numbers because our exponent is effectively of
 450      * unlimited magnitude.  The fCount value contains the number of significant
 451      * digits present in fDigits[].
 452      * <P>
 453      * Zero is represented by any DigitList with fCount == 0 or with each fDigits[i]
 454      * for all i <= fCount == '0'.
 455      *
 456      * int32_t                         fDecimalAt;
 457      * int32_t                         fCount;
 458      * UBool                           fIsPositive;
 459      * char                            *fDigits;
 460      * DecimalFormat::ERoundingMode    fRoundingMode;
 461      */
 462
 463 public:
 464     decContext    fContext;   // public access to status flags.
 465
 466 private:
 467     decNumber     *fDecNumber;
 468     MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>  fStorage;
 469
 470     /* Cached double value corresponding to this decimal number.
 471      * This is an optimization for the formatting implementation, which may
 472      * ask for the double value multiple times.
 473      */
 474     union DoubleOrInt64 {
 475       double        fDouble;
 476       int64_t       fInt64;
 477     } fUnion;
 478     enum EHave {
 479       kNone=0,
 480       kDouble
 481     } fHave;
 482
 483
 484
 485     UBool shouldRoundUp(int32_t maximumDigits) const;
 486
 487  public:
 488
 489 #if U_OVERRIDE_CXX_ALLOCATION
 490     using UMemory::operator new;
 491     using UMemory::operator delete;
 492 #else
 493     static inline void * U_EXPORT2 operator new(size_t size) U_NO_THROW { return ::operator new(size); };
 494     static inline void U_EXPORT2 operator delete(void *ptr )  U_NO_THROW { ::operator delete(ptr); };
 495 #endif
 496     static char U_EXPORT2 getStrtodDecimalSeparator();
 497
 498     /**
 499      * Placement new for stack usage
 500      * @internal
 501      */
 502     static inline void * U_EXPORT2 operator new(size_t /*size*/, void * onStack, EStackMode  /*mode*/) U_NO_THROW { return onStack; }
 503
 504     /**
 505      * Placement delete for stack usage
 506      * @internal
 507      */
 508     static inline void U_EXPORT2 operator delete(void * /*ptr*/, void * /*onStack*/, EStackMode /*mode*/)  U_NO_THROW {}
 509
 510  private:
 511     inline void internalSetDouble(double d) {
 512       fHave = kDouble;
 513       fUnion.fDouble=d;
 514     }
 515     inline void internalClear() {
 516       fHave = kNone;
 517     }
 518 };
 519
 520
 521 U_NAMESPACE_END
 522
 523 #endif // #if !UCONFIG_NO_FORMATTING
 524 #endif // _DIGITLST
 525
 526 //eof