icuSources/i18n/digitlst.h

   1 /*
   2 ******************************************************************************
   3 *
   4 *   Copyright (C) 1997-2010, 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
  55 // Export an explicit template instantiation of the MaybeStackHeaderAndArray that
  56 //    is used as a data member of DigitList.
  57 //
  58 //    MSVC requires this, even though it should not be necessary.
  59 //    No direct access to the MaybeStackHeaderAndArray leaks out of the i18n library.
  60 //
  61 //    Macintosh produces duplicate definition linker errors with the explicit template
  62 //    instantiation.
  63 //
  64 #if !defined(U_DARWIN)
  65 template class U_I18N_API MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>;
  66 #endif
  67
  68
  69 /**
  70  * Digit List is actually a Decimal Floating Point number.
  71  * The original implementation has been replaced by a thin wrapper onto a
  72  * decimal number from the decNumber library.
  73  *
  74  * The original DigitList API has been retained, to minimize the impact of
  75  * the change on the rest of the ICU formatting code.
  76  *
  77  * The change to decNumber enables support for big decimal numbers, and
  78  * allows rounding computations to be done directly in decimal, avoiding
  79  * extra, and inaccurate, conversions to and from doubles.
  80  *
  81  * Original DigitList comments:
  82  *
  83  * Digit List utility class. Private to DecimalFormat.  Handles the transcoding
  84  * between numeric values and strings of characters.  Only handles
  85  * non-negative numbers.  The division of labor between DigitList and
  86  * DecimalFormat is that DigitList handles the radix 10 representation
  87  * issues; DecimalFormat handles the locale-specific issues such as
  88  * positive/negative, grouping, decimal point, currency, and so on.
  89  * <P>
  90  * A DigitList is really a representation of a floating point value.
  91  * It may be an integer value; we assume that a double has sufficient
  92  * precision to represent all digits of a long.
  93  * <P>
  94  * The DigitList representation consists of a string of characters,
  95  * which are the digits radix 10, from '0' to '9'.  It also has a radix
  96  * 10 exponent associated with it.  The value represented by a DigitList
  97  * object can be computed by mulitplying the fraction f, where 0 <= f < 1,
  98  * derived by placing all the digits of the list to the right of the
  99  * decimal point, by 10^exponent.
 100  *
 101  * --------
 102  *
 103  * DigitList vs. decimalNumber:
 104  *
 105  *    DigitList stores digits with the most significant first.
 106  *    decNumber stores digits with the least significant first.
 107  *
 108  *    DigitList, decimal point is before the most significant.
 109  *    decNumber, decimal point is after the least signficant digit.
 110  *
 111  *       digitList:    0.ddddd * 10 ^ exp
 112  *       decNumber:    ddddd. * 10 ^ exp
 113  *
 114  *       digitList exponent = decNumber exponent + digit count
 115  *
 116  *    digitList, digits are platform invariant chars, '0' - '9'
 117  *    decNumber, digits are binary, one per byte, 0 - 9.
 118  *
 119  *       (decNumber library is configurable in how digits are stored, ICU has configured
 120  *        it this way for convenience in replacing the old DigitList implementation.)
 121  */
 122 class U_I18N_API DigitList : public UMemory { // Declare external to make compiler happy
 123 public:
 124
 125     DigitList();
 126     ~DigitList();
 127
 128     /* copy constructor
 129      * @param DigitList The object to be copied.
 130      * @return the newly created object.
 131      */
 132     DigitList(const DigitList&); // copy constructor
 133
 134     /* assignment operator
 135      * @param DigitList The object to be copied.
 136      * @return the newly created object.
 137      */
 138     DigitList& operator=(const DigitList&);  // assignment operator
 139
 140     /**
 141      * Return true if another object is semantically equal to this one.
 142      * @param other The DigitList to be compared for equality
 143      * @return true if another object is semantically equal to this one.
 144      * return false otherwise.
 145      */
 146     UBool operator==(const DigitList& other) const;
 147
 148     int32_t  compare(const DigitList& other);
 149
 150
 151     inline UBool operator!=(const DigitList& other) const { return !operator==(other); };
 152
 153     /**
 154      * Clears out the digits.
 155      * Use before appending them.
 156      * Typically, you set a series of digits with append, then at the point
 157      * you hit the decimal point, you set myDigitList.fDecimalAt = myDigitList.fCount;
 158      * then go on appending digits.
 159      */
 160     void clear(void);
 161
 162     /**
 163      *  Remove, by rounding, any fractional part of the decimal number,
 164      *  leaving an integer value.
 165      */
 166     void toIntegralValue();
 167
 168     /**
 169      * Appends digits to the list.
 170      *    CAUTION:  this function is not recommended for new code.
 171      *              In the original DigitList implementation, decimal numbers were
 172      *              parsed by appending them to a digit list as they were encountered.
 173      *              With the revamped DigitList based on decNumber, append is very
 174      *              inefficient, and the interaction with the exponent value is confusing.
 175      *              Best avoided.
 176      *              TODO:  remove this function once all use has been replaced.
 177      *              TODO:  describe alternative to append()
 178      * @param digit The digit to be appended.
 179      */
 180     void append(char digit);
 181
 182     /**
 183      * Utility routine to get the value of the digit list
 184      * Returns 0.0 if zero length.
 185      * @return the value of the digit list.
 186      */
 187     double getDouble(void) const;
 188
 189     /**
 190      * Utility routine to get the value of the digit list
 191      * Make sure that fitsIntoLong() is called before calling this function.
 192      * Returns 0 if zero length.
 193      * @return the value of the digit list, return 0 if it is zero length
 194      */
 195     int32_t getLong(void) /*const*/;
 196
 197     /**
 198      * Utility routine to get the value of the digit list
 199      * Make sure that fitsIntoInt64() is called before calling this function.
 200      * Returns 0 if zero length.
 201      * @return the value of the digit list, return 0 if it is zero length
 202      */
 203     int64_t getInt64(void) /*const*/;
 204
 205     /**
 206      *  Utility routine to get the value of the digit list as a decimal string.
 207      */
 208     void getDecimal(CharString &str, UErrorCode &status);
 209
 210     /**
 211      * Return true if the number represented by this object can fit into
 212      * a long.
 213      * @param ignoreNegativeZero True if negative zero is ignored.
 214      * @return true if the number represented by this object can fit into
 215      * a long, return false otherwise.
 216      */
 217     UBool fitsIntoLong(UBool ignoreNegativeZero) /*const*/;
 218
 219     /**
 220      * Return true if the number represented by this object can fit into
 221      * an int64_t.
 222      * @param ignoreNegativeZero True if negative zero is ignored.
 223      * @return true if the number represented by this object can fit into
 224      * a long, return false otherwise.
 225      */
 226     UBool fitsIntoInt64(UBool ignoreNegativeZero) /*const*/;
 227
 228     /**
 229      * Utility routine to set the value of the digit list from a double.
 230      * @param source The value to be set
 231      */
 232     void set(double source);
 233
 234     /**
 235      * Utility routine to set the value of the digit list from a long.
 236      * If a non-zero maximumDigits is specified, no more than that number of
 237      * significant digits will be produced.
 238      * @param source The value to be set
 239      */
 240     void set(int32_t source);
 241
 242     /**
 243      * Utility routine to set the value of the digit list from an int64.
 244      * If a non-zero maximumDigits is specified, no more than that number of
 245      * significant digits will be produced.
 246      * @param source The value to be set
 247      */
 248     void set(int64_t source);
 249
 250    /**
 251      * Utility routine to set the value of the digit list from a decimal number
 252      * string.
 253      * @param source The value to be set.  The string must be nul-terminated.
 254      */
 255     void set(const StringPiece &source, UErrorCode &status);
 256
 257     /**
 258      * Multiply    this = this * arg
 259      *    This digitlist will be expanded if necessary to accomodate the result.
 260      *  @param arg  the number to multiply by.
 261      */
 262     void mult(const DigitList &arg, UErrorCode &status);
 263
 264     /**
 265      *   Divide    this = this / arg
 266      */
 267     void div(const DigitList &arg, UErrorCode &status);
 268
 269     //  The following functions replace direct access to the original DigitList implmentation
 270     //  data structures.
 271
 272     void setRoundingMode(DecimalFormat::ERoundingMode m);
 273
 274     /** Test a number for zero.
 275      * @return  TRUE if the number is zero
 276      */
 277     UBool isZero(void) const;
 278
 279     /** Test for a Nan
 280      * @return  TRUE if the number is a NaN
 281      */
 282     UBool isNaN(void) const {return decNumberIsNaN(fDecNumber);};
 283
 284     UBool isInfinite() const {return decNumberIsInfinite(fDecNumber);};
 285
 286     /**  Reduce, or normalize.  Removes trailing zeroes, adjusts exponent appropriately. */
 287     void     reduce();
 288
 289     /**  Remove trailing fraction zeros, adjust exponent accordingly. */
 290     void     trim();
 291
 292     /** Set to zero */
 293     void     setToZero() {uprv_decNumberZero(fDecNumber);};
 294
 295     /** get the number of digits in the decimal number */
 296     int32_t  digits() const {return fDecNumber->digits;};
 297
 298     /**
 299      * Round the number to the given number of digits.
 300      * @param maximumDigits The maximum number of digits to be shown.
 301      * Upon return, count will be less than or equal to maximumDigits.
 302      */
 303     void round(int32_t maximumDigits);
 304
 305     void roundFixedPoint(int32_t maximumFractionDigits);
 306
 307     /** Ensure capacity for digits.  Grow the storage if it is currently less than
 308      *      the requested size.   Capacity is not reduced if it is already greater
 309      *      than requested.
 310      */
 311     void  ensureCapacity(int32_t  requestedSize, UErrorCode &status);
 312
 313     UBool    isPositive(void) const { return decNumberIsNegative(fDecNumber) == 0;};
 314     void     setPositive(UBool s);
 315
 316     void     setDecimalAt(int32_t d);
 317     int32_t  getDecimalAt();
 318
 319     void     setCount(int32_t c);
 320     int32_t  getCount() const;
 321
 322     /**
 323      * Set the digit in platform (invariant) format, from '0'..'9'
 324      * @param i index of digit
 325      * @param v digit value, from '0' to '9' in platform invariant format
 326      */
 327     void     setDigit(int32_t i, char v);
 328
 329     /**
 330      * Get the digit in platform (invariant) format, from '0'..'9' inclusive
 331      * @param i index of digit
 332      * @return invariant format of the digit
 333      */
 334     char     getDigit(int32_t i);
 335
 336
 337     /**
 338      * Get the digit's value, as an integer from 0..9 inclusive.
 339      * Note that internally this value is a decNumberUnit, but ICU configures it to be a uint8_t.
 340      * @param i index of digit
 341      * @return value of that digit
 342      */
 343     uint8_t     getDigitValue(int32_t i);
 344
 345
 346 private:
 347     /*
 348      * These data members are intentionally public and can be set directly.
 349      *<P>
 350      * The value represented is given by placing the decimal point before
 351      * fDigits[fDecimalAt].  If fDecimalAt is < 0, then leading zeros between
 352      * the decimal point and the first nonzero digit are implied.  If fDecimalAt
 353      * is > fCount, then trailing zeros between the fDigits[fCount-1] and the
 354      * decimal point are implied.
 355      * <P>
 356      * Equivalently, the represented value is given by f * 10^fDecimalAt.  Here
 357      * f is a value 0.1 <= f < 1 arrived at by placing the digits in fDigits to
 358      * the right of the decimal.
 359      * <P>
 360      * DigitList is normalized, so if it is non-zero, fDigits[0] is non-zero.  We
 361      * don't allow denormalized numbers because our exponent is effectively of
 362      * unlimited magnitude.  The fCount value contains the number of significant
 363      * digits present in fDigits[].
 364      * <P>
 365      * Zero is represented by any DigitList with fCount == 0 or with each fDigits[i]
 366      * for all i <= fCount == '0'.
 367      *
 368      * int32_t                         fDecimalAt;
 369      * int32_t                         fCount;
 370      * UBool                           fIsPositive;
 371      * char                            *fDigits;
 372      * DecimalFormat::ERoundingMode    fRoundingMode;
 373      */
 374
 375 private:
 376
 377     decContext    fContext;
 378     decNumber     *fDecNumber;
 379     MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>  fStorage;
 380
 381     /* Cached double value corresponding to this decimal number.
 382      * This is an optimization for the formatting implementation, which may
 383      * ask for the double value multiple times.
 384      */
 385     double        fDouble;
 386     UBool         fHaveDouble;
 387
 388
 389
 390     UBool shouldRoundUp(int32_t maximumDigits) const;
 391 };
 392
 393
 394 U_NAMESPACE_END
 395
 396 #endif // #if !UCONFIG_NO_FORMATTING
 397 #endif // _DIGITLST
 398
 399 //eof