Check in the pristine copy of ICU 4.6...

icu46/source/i18n/digitlst.h

+/*
+******************************************************************************
+*
+*   Copyright (C) 1997-2010, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*
+* File DIGITLST.H
+*
+* Modification History:
+*
+*   Date        Name        Description
+*   02/25/97    aliu        Converted from java.
+*   03/21/97    clhuang     Updated per C++ implementation.
+*   04/15/97    aliu        Changed MAX_COUNT to DBL_DIG.  Changed Digit to char.
+*   09/09/97    aliu        Adapted for exponential notation support.
+*   08/02/98    stephen     Added nearest/even rounding
+*   06/29/99    stephen     Made LONG_DIGITS a macro to satisfy SUN compiler
+*   07/09/99    stephen     Removed kMaxCount (unused, for HP compiler)
+******************************************************************************
+*/
+ 
+#ifndef DIGITLST_H
+#define DIGITLST_H
+ 
+#include "unicode/uobject.h"
+
+#if !UCONFIG_NO_FORMATTING
+#include "unicode/decimfmt.h"
+#include <float.h>
+#include "decContext.h"
+#include "decNumber.h"
+#include "cmemory.h"
+
+// Decimal digits in a 64-bit int
+#define INT64_DIGITS 19
+
+typedef enum EDigitListValues {
+    MAX_DBL_DIGITS = DBL_DIG,
+    MAX_I64_DIGITS = INT64_DIGITS,
+    MAX_DIGITS = MAX_I64_DIGITS,
+    MAX_EXPONENT = DBL_DIG,
+    DIGIT_PADDING = 3,
+    DEFAULT_DIGITS = 40,   // Initial storage size, will grow as needed.
+
+     // "+." + fDigits + "e" + fDecimalAt
+    MAX_DEC_DIGITS = MAX_DIGITS + DIGIT_PADDING + MAX_EXPONENT
+} EDigitListValues;
+
+U_NAMESPACE_BEGIN
+
+class CharString;
+
+// Export an explicit template instantiation of the MaybeStackHeaderAndArray that
+//    is used as a data member of DigitList.
+//
+//    MSVC requires this, even though it should not be necessary. 
+//    No direct access to the MaybeStackHeaderAndArray leaks out of the i18n library.
+//
+//    Macintosh produces duplicate definition linker errors with the explicit template
+//    instantiation.
+//
+#if !defined(U_DARWIN)
+template class U_I18N_API MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>;
+#endif
+
+
+/**
+ * Digit List is actually a Decimal Floating Point number.
+ * The original implementation has been replaced by a thin wrapper onto a 
+ * decimal number from the decNumber library.
+ *
+ * The original DigitList API has been retained, to minimize the impact of
+ * the change on the rest of the ICU formatting code.
+ *
+ * The change to decNumber enables support for big decimal numbers, and
+ * allows rounding computations to be done directly in decimal, avoiding
+ * extra, and inaccurate, conversions to and from doubles.
+ *
+ * Original DigitList comments:
+ *
+ * Digit List utility class. Private to DecimalFormat.  Handles the transcoding
+ * between numeric values and strings of characters.  Only handles
+ * non-negative numbers.  The division of labor between DigitList and
+ * DecimalFormat is that DigitList handles the radix 10 representation
+ * issues; DecimalFormat handles the locale-specific issues such as
+ * positive/negative, grouping, decimal point, currency, and so on.
+ * <P>
+ * A DigitList is really a representation of a floating point value.
+ * It may be an integer value; we assume that a double has sufficient
+ * precision to represent all digits of a long.
+ * <P>
+ * The DigitList representation consists of a string of characters,
+ * which are the digits radix 10, from '0' to '9'.  It also has a radix
+ * 10 exponent associated with it.  The value represented by a DigitList
+ * object can be computed by mulitplying the fraction f, where 0 <= f < 1,
+ * derived by placing all the digits of the list to the right of the
+ * decimal point, by 10^exponent.
+ *
+ * --------
+ *
+ * DigitList vs. decimalNumber:
+ *
+ *    DigitList stores digits with the most significant first.
+ *    decNumber stores digits with the least significant first.
+ *
+ *    DigitList, decimal point is before the most significant.
+ *    decNumber, decimal point is after the least signficant digit.
+ *
+ *       digitList:    0.ddddd * 10 ^ exp
+ *       decNumber:    ddddd. * 10 ^ exp
+ *
+ *       digitList exponent = decNumber exponent + digit count
+ *
+ *    digitList, digits are platform invariant chars, '0' - '9'
+ *    decNumber, digits are binary, one per byte, 0 - 9.
+ *
+ *       (decNumber library is configurable in how digits are stored, ICU has configured
+ *        it this way for convenience in replacing the old DigitList implementation.)
+ */
+class U_I18N_API DigitList : public UMemory { // Declare external to make compiler happy
+public:
+
+    DigitList();
+    ~DigitList();
+
+    /* copy constructor
+     * @param DigitList The object to be copied.
+     * @return the newly created object. 
+     */
+    DigitList(const DigitList&); // copy constructor
+
+    /* assignment operator
+     * @param DigitList The object to be copied.
+     * @return the newly created object.
+     */
+    DigitList& operator=(const DigitList&);  // assignment operator
+
+    /**
+     * Return true if another object is semantically equal to this one.
+     * @param other The DigitList to be compared for equality
+     * @return true if another object is semantically equal to this one.
+     * return false otherwise.
+     */
+    UBool operator==(const DigitList& other) const;
+
+    int32_t  compare(const DigitList& other);
+
+
+    inline UBool operator!=(const DigitList& other) const { return !operator==(other); };
+
+    /**
+     * Clears out the digits.
+     * Use before appending them.
+     * Typically, you set a series of digits with append, then at the point
+     * you hit the decimal point, you set myDigitList.fDecimalAt = myDigitList.fCount;
+     * then go on appending digits.
+     */
+    void clear(void);
+
+    /**
+     *  Remove, by rounding, any fractional part of the decimal number,
+     *  leaving an integer value.
+     */
+    void toIntegralValue();
+    
+    /**
+     * Appends digits to the list. 
+     *    CAUTION:  this function is not recommended for new code.
+     *              In the original DigitList implementation, decimal numbers were
+     *              parsed by appending them to a digit list as they were encountered.
+     *              With the revamped DigitList based on decNumber, append is very
+     *              inefficient, and the interaction with the exponent value is confusing.
+     *              Best avoided.
+     *              TODO:  remove this function once all use has been replaced.
+     *              TODO:  describe alternative to append()
+     * @param digit The digit to be appended.
+     */
+    void append(char digit);
+
+    /**
+     * Utility routine to get the value of the digit list
+     * Returns 0.0 if zero length.
+     * @return the value of the digit list.
+     */
+    double getDouble(void) const;
+
+    /**
+     * Utility routine to get the value of the digit list
+     * Make sure that fitsIntoLong() is called before calling this function.
+     * Returns 0 if zero length.
+     * @return the value of the digit list, return 0 if it is zero length
+     */
+    int32_t getLong(void) /*const*/;
+
+    /**
+     * Utility routine to get the value of the digit list
+     * Make sure that fitsIntoInt64() is called before calling this function.
+     * Returns 0 if zero length.
+     * @return the value of the digit list, return 0 if it is zero length
+     */
+    int64_t getInt64(void) /*const*/;
+
+    /**
+     *  Utility routine to get the value of the digit list as a decimal string.
+     */
+    void getDecimal(CharString &str, UErrorCode &status);
+
+    /**
+     * Return true if the number represented by this object can fit into
+     * a long.
+     * @param ignoreNegativeZero True if negative zero is ignored.
+     * @return true if the number represented by this object can fit into
+     * a long, return false otherwise.
+     */
+    UBool fitsIntoLong(UBool ignoreNegativeZero) /*const*/;
+
+    /**
+     * Return true if the number represented by this object can fit into
+     * an int64_t.
+     * @param ignoreNegativeZero True if negative zero is ignored.
+     * @return true if the number represented by this object can fit into
+     * a long, return false otherwise.
+     */
+    UBool fitsIntoInt64(UBool ignoreNegativeZero) /*const*/;
+
+    /**
+     * Utility routine to set the value of the digit list from a double.
+     * @param source The value to be set
+     */
+    void set(double source);
+
+    /**
+     * Utility routine to set the value of the digit list from a long.
+     * If a non-zero maximumDigits is specified, no more than that number of
+     * significant digits will be produced.
+     * @param source The value to be set
+     */
+    void set(int32_t source);
+
+    /**
+     * Utility routine to set the value of the digit list from an int64.
+     * If a non-zero maximumDigits is specified, no more than that number of
+     * significant digits will be produced.
+     * @param source The value to be set
+     */
+    void set(int64_t source);
+
+   /**
+     * Utility routine to set the value of the digit list from a decimal number
+     * string.
+     * @param source The value to be set.  The string must be nul-terminated.
+     */
+    void set(const StringPiece &source, UErrorCode &status);
+
+    /**
+     * Multiply    this = this * arg
+     *    This digitlist will be expanded if necessary to accomodate the result.
+     *  @param arg  the number to multiply by.
+     */
+    void mult(const DigitList &arg, UErrorCode &status);
+
+    /**
+     *   Divide    this = this / arg
+     */
+    void div(const DigitList &arg, UErrorCode &status);
+
+    //  The following functions replace direct access to the original DigitList implmentation
+    //  data structures.
+
+    void setRoundingMode(DecimalFormat::ERoundingMode m); 
+
+    /** Test a number for zero.
+     * @return  TRUE if the number is zero
+     */
+    UBool isZero(void) const;
+
+    /** Test for a Nan
+     * @return  TRUE if the number is a NaN
+     */
+    UBool isNaN(void) const {return decNumberIsNaN(fDecNumber);};
+
+    UBool isInfinite() const {return decNumberIsInfinite(fDecNumber);};
+
+    /**  Reduce, or normalize.  Removes trailing zeroes, adjusts exponent appropriately. */
+    void     reduce();
+
+    /**  Remove trailing fraction zeros, adjust exponent accordingly. */
+    void     trim();
+
+    /** Set to zero */
+    void     setToZero() {uprv_decNumberZero(fDecNumber);};
+
+    /** get the number of digits in the decimal number */
+    int32_t  digits() const {return fDecNumber->digits;};
+
+    /**
+     * Round the number to the given number of digits.
+     * @param maximumDigits The maximum number of digits to be shown.
+     * Upon return, count will be less than or equal to maximumDigits.
+     */
+    void round(int32_t maximumDigits);
+
+    void roundFixedPoint(int32_t maximumFractionDigits);
+
+    /** Ensure capacity for digits.  Grow the storage if it is currently less than
+     *      the requested size.   Capacity is not reduced if it is already greater
+     *      than requested.
+     */
+    void  ensureCapacity(int32_t  requestedSize, UErrorCode &status); 
+
+    UBool    isPositive(void) const { return decNumberIsNegative(fDecNumber) == 0;};
+    void     setPositive(UBool s); 
+
+    void     setDecimalAt(int32_t d);
+    int32_t  getDecimalAt();
+
+    void     setCount(int32_t c);
+    int32_t  getCount() const;
+    
+    /**
+     * Set the digit in platform (invariant) format, from '0'..'9'
+     * @param i index of digit
+     * @param v digit value, from '0' to '9' in platform invariant format
+     */
+    void     setDigit(int32_t i, char v);
+
+    /**
+     * Get the digit in platform (invariant) format, from '0'..'9' inclusive
+     * @param i index of digit
+     * @return invariant format of the digit
+     */
+    char     getDigit(int32_t i);
+
+
+    /**
+     * Get the digit's value, as an integer from 0..9 inclusive.
+     * Note that internally this value is a decNumberUnit, but ICU configures it to be a uint8_t.
+     * @param i index of digit
+     * @return value of that digit
+     */
+    uint8_t     getDigitValue(int32_t i);
+
+
+private:
+    /*
+     * These data members are intentionally public and can be set directly.
+     *<P>
+     * The value represented is given by placing the decimal point before
+     * fDigits[fDecimalAt].  If fDecimalAt is < 0, then leading zeros between
+     * the decimal point and the first nonzero digit are implied.  If fDecimalAt
+     * is > fCount, then trailing zeros between the fDigits[fCount-1] and the
+     * decimal point are implied.
+     * <P>
+     * Equivalently, the represented value is given by f * 10^fDecimalAt.  Here
+     * f is a value 0.1 <= f < 1 arrived at by placing the digits in fDigits to
+     * the right of the decimal.
+     * <P>
+     * DigitList is normalized, so if it is non-zero, fDigits[0] is non-zero.  We
+     * don't allow denormalized numbers because our exponent is effectively of
+     * unlimited magnitude.  The fCount value contains the number of significant
+     * digits present in fDigits[].
+     * <P>
+     * Zero is represented by any DigitList with fCount == 0 or with each fDigits[i]
+     * for all i <= fCount == '0'.
+     *
+     * int32_t                         fDecimalAt;
+     * int32_t                         fCount;
+     * UBool                           fIsPositive;
+     * char                            *fDigits;
+     * DecimalFormat::ERoundingMode    fRoundingMode;
+     */
+
+private:
+
+    decContext    fContext;
+    decNumber     *fDecNumber;
+    MaybeStackHeaderAndArray<decNumber, char, DEFAULT_DIGITS>  fStorage;
+
+    /* Cached double value corresponding to this decimal number.
+     * This is an optimization for the formatting implementation, which may
+     * ask for the double value multiple times.
+     */
+    double        fDouble;
+    UBool         fHaveDouble;
+
+
+
+    UBool shouldRoundUp(int32_t maximumDigits) const;
+};
+
+
+U_NAMESPACE_END
+
+#endif // #if !UCONFIG_NO_FORMATTING
+#endif // _DIGITLST
+
+//eof