195 lines
6.9 KiB
C++
195 lines
6.9 KiB
C++
/*
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********************************************************************************
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* *
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* COPYRIGHT: *
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* (C) Copyright Taligent, Inc., 1997 *
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* (C) Copyright International Business Machines Corporation, 1997-1999 *
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* Licensed Material - Program-Property of IBM - All Rights Reserved. *
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* US Government Users Restricted Rights - Use, duplication, or disclosure *
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* restricted by GSA ADP Schedule Contract with IBM Corp. *
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* *
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********************************************************************************
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*
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* File DIGITLST.H
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*
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* Modification History:
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*
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* Date Name Description
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* 02/25/97 aliu Converted from java.
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* 03/21/97 clhuang Updated per C++ implementation.
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* 04/15/97 aliu Changed MAX_COUNT to DBL_DIG. Changed Digit to char.
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* 09/09/97 aliu Adapted for exponential notation support.
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* 08/02/98 stephen Added nearest/even rounding
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* 06/29/99 stephen Made LONG_DIGITS a macro to satisfy SUN compiler
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* 07/09/99 stephen Removed kMaxCount (unused, for HP compiler)
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*******************************************************************************
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*/
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#ifndef DIGITLST_H
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#define DIGITLST_H
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#include "utypes.h"
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#include <float.h>
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// Decimal digits in a 32-bit int
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#define LONG_DIGITS 19
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/**
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* Digit List. Private to DecimalFormat. Handles the transcoding
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* between numeric values and strings of characters. Only handles
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* non-negative numbers. The division of labor between DigitList and
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* DecimalFormat is that DigitList handles the radix 10 representation
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* issues; DecimalFormat handles the locale-specific issues such as
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* positive/negative, grouping, decimal point, currency, and so on.
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* <P>
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* A DigitList is really a representation of a floating point value.
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* It may be an integer value; we assume that a double has sufficient
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* precision to represent all digits of a long.
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* <P>
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* The DigitList representation consists of a string of characters,
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* which are the digits radix 10, from '0' to '9'. It also has a radix
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* 10 exponent associated with it. The value represented by a DigitList
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* object can be computed by mulitplying the fraction f, where 0 <= f < 1,
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* derived by placing all the digits of the list to the right of the
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* decimal point, by 10^exponent.
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*/
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class U_COMMON_API DigitList { // Declare external to make compiler happy
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public:
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DigitList();
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~DigitList(); // Make this virtual if subclassing is desired later
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DigitList(const DigitList&); // copy constructor
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DigitList& operator=(const DigitList&); // assignment operator
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/**
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* Return true if another object is semantically equal to this one.
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*/
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bool_t operator==(const DigitList& other) const;
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/**
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* Return true if another object is semantically unequal to this one.
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*/
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bool_t operator!=(const DigitList& other) const { return !operator==(other); }
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/**
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* Clears out the digits.
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* Use before appending them.
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* Typically, you set a series of digits with append, then at the point
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* you hit the decimal point, you set myDigitList.fDecimalAt = myDigitList.fCount;
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* then go on appending digits.
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*/
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virtual void clear(void);
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/**
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* Appends digits to the list. Ignores all digits beyond the first DBL_DIG,
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* since they are not significant for either longs or doubles.
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*/
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virtual void append(char digit);
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/**
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* Utility routine to get the value of the digit list
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* Returns 0.0 if zero length.
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*/
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double getDouble(void) const;
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/**
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* Utility routine to get the value of the digit list
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* Returns 0 if zero length.
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*/
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int32_t getLong(void) const;
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/**
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* Return true if the number represented by this object can fit into
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* a long.
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*/
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bool_t fitsIntoLong(bool_t isPositive, bool_t ignoreNegativeZero);
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/**
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* Utility routine to set the value of the digit list from a double
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* Input must be non-negative, and must not be Inf, -Inf, or NaN.
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* The maximum fraction digits helps us round properly.
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*/
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void set(double source, int32_t maximumDigits, bool_t fixedPoint = TRUE);
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/**
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* Utility routine to set the value of the digit list from a long.
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* If a non-zero maximumDigits is specified, no more than that number of
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* significant digits will be produced.
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*/
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void set(int32_t source, int32_t maximumDigits = 0);
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/**
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* Return true if this is a representation of zero.
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*/
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bool_t isZero(void) const;
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/**
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* Return true if this is a representation of LONG_MIN. You must use
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* this method to determine if this is so; you cannot check directly,
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* because a special format is used to handle this.
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*/
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bool_t isLONG_MIN(void) const;
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/**
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* This is the zero digit. Array elements fDigits[i] have values from
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* kZero to kZero + 9. Typically, this is '0'.
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*/
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static const char kZero;
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public:
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/**
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* These data members are intentionally public and can be set directly.
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*<P>
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* The value represented is given by placing the decimal point before
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* fDigits[fDecimalAt]. If fDecimalAt is < 0, then leading zeros between
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* the decimal point and the first nonzero digit are implied. If fDecimalAt
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* is > fCount, then trailing zeros between the fDigits[fCount-1] and the
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* decimal point are implied.
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* <P>
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* Equivalently, the represented value is given by f * 10^fDecimalAt. Here
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* f is a value 0.1 <= f < 1 arrived at by placing the digits in fDigits to
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* the right of the decimal.
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* <P>
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* DigitList is normalized, so if it is non-zero, fDigits[0] is non-zero. We
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* don't allow denormalized numbers because our exponent is effectively of
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* unlimited magnitude. The fCount value contains the number of significant
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* digits present in fDigits[].
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* <P>
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* Zero is represented by any DigitList with fCount == 0 or with each fDigits[i]
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* for all i <= fCount == '0'.
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*/
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int32_t fDecimalAt;
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int32_t fCount;
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private:
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enum { MAX_DIGITS = DBL_DIG };
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public:
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char fDigits[MAX_DIGITS];
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private:
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/**
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* Round the representation to the given number of digits.
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* @param maximumDigits The maximum number of digits to be shown.
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* Upon return, count will be less than or equal to maximumDigits.
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*/
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void round(int32_t maximumDigits);
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/**
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* Initializes the buffer that records the mimimum long value.
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*/
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static void initializeLONG_MIN_REP(void);
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bool_t shouldRoundUp(int32_t maximumDigits);
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static char LONG_MIN_REP[LONG_DIGITS];
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static int32_t LONG_MIN_REP_LENGTH;
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};
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#endif // _DIGITLST
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//eof
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