icu/math/MathContext.java

//  2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/* Generated from 'MathContext.nrx' 8 Sep 2000 11:07:48 [v2.00] */
/* Options: Binary Comments Crossref Format Java Logo Strictargs Strictcase Trace2 Verbose3 */
package com.ibm.icu.math;

/* ------------------------------------------------------------------ */
/* MathContext -- Math context settings                               */
/* ------------------------------------------------------------------ */
/* Copyright IBM Corporation, 1997, 2000, 2005, 2007.  All Rights Reserved. */
/*                                                                    */
/*   The MathContext object encapsulates the settings used by the     */
/*   BigDecimal class; it could also be used by other arithmetics.    */
/* ------------------------------------------------------------------ */
/* Notes:                                                             */
/*                                                                    */
/* 1. The properties are checked for validity on construction, so     */
/*    the BigDecimal class may assume that they are correct.          */
/* ------------------------------------------------------------------ */
/* Author:    Mike Cowlishaw                                          */
/* 1997.09.03 Initial version (edited from netrexx.lang.RexxSet)      */
/* 1997.09.12 Add lostDigits property                                 */
/* 1998.05.02 Make the class immutable and final; drop set methods    */
/* 1998.06.05 Add Round (rounding modes) property                     */
/* 1998.06.25 Rename from DecimalContext; allow digits=0              */
/* 1998.10.12 change to com.ibm.icu.math package                          */
/* 1999.02.06 add javadoc comments                                    */
/* 1999.03.05 simplify; changes from discussion with J. Bloch         */
/* 1999.03.13 1.00 release to IBM Centre for Java Technology          */
/* 1999.07.10 1.04 flag serialization unused                          */
/* 2000.01.01 1.06 copyright update                                   */
/* ------------------------------------------------------------------ */


/**
 * The <code>MathContext</code> immutable class encapsulates the
 * settings understood by the operator methods of the {@link BigDecimal}
 * class (and potentially other classes).  Operator methods are those
 * that effect an operation on a number or a pair of numbers.
 * <p>
 * The settings, which are not base-dependent, comprise:
 * <ol>
 * <li><code>digits</code>:
 * the number of digits (precision) to be used for an operation
 * <li><code>form</code>:
 * the form of any exponent that results from the operation
 * <li><code>lostDigits</code>:
 * whether checking for lost digits is enabled
 * <li><code>roundingMode</code>:
 * the algorithm to be used for rounding.
 * </ol>
 * <p>
 * When provided, a <code>MathContext</code> object supplies the
 * settings for an operation directly.
 * <p>
 * When <code>MathContext.DEFAULT</code> is provided for a
 * <code>MathContext</code> parameter then the default settings are used
 * (<code>9, SCIENTIFIC, false, ROUND_HALF_UP</code>).
 * <p>
 * In the <code>BigDecimal</code> class, all methods which accept a
 * <code>MathContext</code> object defaults) also have a version of the
 * method which does not accept a MathContext parameter.  These versions
 * carry out unlimited precision fixed point arithmetic (as though the
 * settings were (<code>0, PLAIN, false, ROUND_HALF_UP</code>).
 * <p>
 * The instance variables are shared with default access (so they are
 * directly accessible to the <code>BigDecimal</code> class), but must
 * never be changed.
 * <p>
 * The rounding mode constants have the same names and values as the
 * constants of the same name in <code>java.math.BigDecimal</code>, to
 * maintain compatibility with earlier versions of
 * <code>BigDecimal</code>.
 *
 * @see     BigDecimal
 * @author  Mike Cowlishaw
 * @stable ICU 2.0
 */

public final class MathContext implements java.io.Serializable{
 //private static final java.lang.String $0="MathContext.nrx";

 /* ----- Properties ----- */
 /* properties public constant */
 /**
  * Plain (fixed point) notation, without any exponent.
  * Used as a setting to control the form of the result of a
  * <code>BigDecimal</code> operation.
  * A zero result in plain form may have a decimal part of one or
  * more zeros.
  *
  * @see #ENGINEERING
  * @see #SCIENTIFIC
  * @stable ICU 2.0
  */
 public static final int PLAIN=0; // [no exponent]

 /**
  * Standard floating point notation (with scientific exponential
  * format, where there is one digit before any decimal point).
  * Used as a setting to control the form of the result of a
  * <code>BigDecimal</code> operation.
  * A zero result in plain form may have a decimal part of one or
  * more zeros.
  *
  * @see #ENGINEERING
  * @see #PLAIN
  * @stable ICU 2.0
  */
 public static final int SCIENTIFIC=1; // 1 digit before .

 /**
  * Standard floating point notation (with engineering exponential
  * format, where the power of ten is a multiple of 3).
  * Used as a setting to control the form of the result of a
  * <code>BigDecimal</code> operation.
  * A zero result in plain form may have a decimal part of one or
  * more zeros.
  *
  * @see #PLAIN
  * @see #SCIENTIFIC
  * @stable ICU 2.0
  */
 public static final int ENGINEERING=2; // 1-3 digits before .

 // The rounding modes match the original BigDecimal class values
 /**
  * Rounding mode to round to a more positive number.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If any of the discarded digits are non-zero then the result
  * should be rounded towards the next more positive digit.
  * @stable ICU 2.0
  */
 public static final int ROUND_CEILING=2;

 /**
  * Rounding mode to round towards zero.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * All discarded digits are ignored (truncated).  The result is
  * neither incremented nor decremented.
  * @stable ICU 2.0
  */
 public static final int ROUND_DOWN=1;

 /**
  * Rounding mode to round to a more negative number.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If any of the discarded digits are non-zero then the result
  * should be rounded towards the next more negative digit.
  * @stable ICU 2.0
  */
 public static final int ROUND_FLOOR=3;

 /**
  * Rounding mode to round to nearest neighbor, where an equidistant
  * value is rounded down.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If the discarded digits represent greater than half (0.5 times)
  * the value of a one in the next position then the result should be
  * rounded up (away from zero).  Otherwise the discarded digits are
  * ignored.
  * @stable ICU 2.0
  */
 public static final int ROUND_HALF_DOWN=5;

 /**
  * Rounding mode to round to nearest neighbor, where an equidistant
  * value is rounded to the nearest even neighbor.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If the discarded digits represent greater than half (0.5 times)
  * the value of a one in the next position then the result should be
  * rounded up (away from zero).  If they represent less than half,
  * then the result should be rounded down.
  * <p>
  * Otherwise (they represent exactly half) the result is rounded
  * down if its rightmost digit is even, or rounded up if its
  * rightmost digit is odd (to make an even digit).
  * @stable ICU 2.0
  */
 public static final int ROUND_HALF_EVEN=6;

 /**
  * Rounding mode to round to nearest neighbor, where an equidistant
  * value is rounded up.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If the discarded digits represent greater than or equal to half
  * (0.5 times) the value of a one in the next position then the result
  * should be rounded up (away from zero).  Otherwise the discarded
  * digits are ignored.
  * @stable ICU 2.0
  */
 public static final int ROUND_HALF_UP=4;

 /**
  * Rounding mode to assert that no rounding is necessary.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * Rounding (potential loss of information) is not permitted.
  * If any of the discarded digits are non-zero then an
  * <code>ArithmeticException</code> should be thrown.
  * @stable ICU 2.0
  */
 public static final int ROUND_UNNECESSARY=7;

 /**
  * Rounding mode to round away from zero.
  * Used as a setting to control the rounding mode used during a
  * <code>BigDecimal</code> operation.
  * <p>
  * If any of the discarded digits are non-zero then the result will
  * be rounded up (away from zero).
  * @stable ICU 2.0
  */
 public static final int ROUND_UP=0;


 /* properties shared */
 /**
  * The number of digits (precision) to be used for an operation.
  * A value of 0 indicates that unlimited precision (as many digits
  * as are required) will be used.
  * <p>
  * The {@link BigDecimal} operator methods use this value to
  * determine the precision of results.
  * Note that leading zeros (in the integer part of a number) are
  * never significant.
  * <p>
  * <code>digits</code> will always be non-negative.
  *
  * @serial
  */
 int digits;

 /**
  * The form of results from an operation.
  * <p>
  * The {@link BigDecimal} operator methods use this value to
  * determine the form of results, in particular whether and how
  * exponential notation should be used.
  *
  * @see #ENGINEERING
  * @see #PLAIN
  * @see #SCIENTIFIC
  * @serial
  */
 int form; // values for this must fit in a byte

 /**
  * Controls whether lost digits checking is enabled for an
  * operation.
  * Set to <code>true</code> to enable checking, or
  * to <code>false</code> to disable checking.
  * <p>
  * When enabled, the {@link BigDecimal} operator methods check
  * the precision of their operand or operands, and throw an
  * <code>ArithmeticException</code> if an operand is more precise
  * than the digits setting (that is, digits would be lost).
  * When disabled, operands are rounded to the specified digits.
  *
  * @serial
  */
 boolean lostDigits;

 /**
  * The rounding algorithm to be used for an operation.
  * <p>
  * The {@link BigDecimal} operator methods use this value to
  * determine the algorithm to be used when non-zero digits have to
  * be discarded in order to reduce the precision of a result.
  * The value must be one of the public constants whose name starts
  * with <code>ROUND_</code>.
  *
  * @see #ROUND_CEILING
  * @see #ROUND_DOWN
  * @see #ROUND_FLOOR
  * @see #ROUND_HALF_DOWN
  * @see #ROUND_HALF_EVEN
  * @see #ROUND_HALF_UP
  * @see #ROUND_UNNECESSARY
  * @see #ROUND_UP
  * @serial
  */
 int roundingMode;

 /* properties private constant */
 // default settings
 private static final int DEFAULT_FORM=SCIENTIFIC;
 private static final int DEFAULT_DIGITS=9;
 private static final boolean DEFAULT_LOSTDIGITS=false;
 private static final int DEFAULT_ROUNDINGMODE=ROUND_HALF_UP;

 /* properties private constant */

 private static final int MIN_DIGITS=0; // smallest value for DIGITS.
 private static final int MAX_DIGITS=999999999; // largest value for DIGITS.  If increased,
 // the BigDecimal class may need update.
 // list of valid rounding mode values, most common two first
 private static final int ROUNDS[]=new int[]{ROUND_HALF_UP,ROUND_UNNECESSARY,ROUND_CEILING,ROUND_DOWN,ROUND_FLOOR,ROUND_HALF_DOWN,ROUND_HALF_EVEN,ROUND_UP};


 private static final java.lang.String ROUNDWORDS[]=new java.lang.String[]{"ROUND_HALF_UP","ROUND_UNNECESSARY","ROUND_CEILING","ROUND_DOWN","ROUND_FLOOR","ROUND_HALF_DOWN","ROUND_HALF_EVEN","ROUND_UP"}; // matching names of the ROUNDS values


 /* properties private constant unused */

 // Serialization version
 private static final long serialVersionUID=7163376998892515376L;

 /* properties public constant */
 /**
  * A <code>MathContext</code> object initialized to the default
  * settings for general-purpose arithmetic.  That is,
  * <code>digits=9 form=SCIENTIFIC lostDigits=false
  * roundingMode=ROUND_HALF_UP</code>.
  *
  * @see #SCIENTIFIC
  * @see #ROUND_HALF_UP
  * @stable ICU 2.0
  */
 public static final com.ibm.icu.math.MathContext DEFAULT=new com.ibm.icu.math.MathContext(DEFAULT_DIGITS,DEFAULT_FORM,DEFAULT_LOSTDIGITS,DEFAULT_ROUNDINGMODE);


 /* ----- Constructors ----- */

 /**
  * Constructs a new <code>MathContext</code> with a specified
  * precision.
  * The other settings are set to the default values
  * (see {@link #DEFAULT}).
  *
  * An <code>IllegalArgumentException</code> is thrown if the
  * <code>setdigits</code> parameter is out of range
  * (&lt;0 or &gt;999999999).
  *
  * @param setdigits     The <code>int</code> digits setting
  *                      for this <code>MathContext</code>.
  * @throws IllegalArgumentException parameter out of range.
  * @stable ICU 2.0
  */

 public MathContext(int setdigits){
  this(setdigits,DEFAULT_FORM,DEFAULT_LOSTDIGITS,DEFAULT_ROUNDINGMODE);
  return;}


 /**
  * Constructs a new <code>MathContext</code> with a specified
  * precision and form.
  * The other settings are set to the default values
  * (see {@link #DEFAULT}).
  *
  * An <code>IllegalArgumentException</code> is thrown if the
  * <code>setdigits</code> parameter is out of range
  * (&lt;0 or &gt;999999999), or if the value given for the
  * <code>setform</code> parameter is not one of the appropriate
  * constants.
  *
  * @param setdigits     The <code>int</code> digits setting
  *                      for this <code>MathContext</code>.
  * @param setform       The <code>int</code> form setting
  *                      for this <code>MathContext</code>.
  * @throws IllegalArgumentException parameter out of range.
  * @stable ICU 2.0
  */

 public MathContext(int setdigits,int setform){
  this(setdigits,setform,DEFAULT_LOSTDIGITS,DEFAULT_ROUNDINGMODE);
  return;}

 /**
  * Constructs a new <code>MathContext</code> with a specified
  * precision, form, and lostDigits setting.
  * The roundingMode setting is set to its default value
  * (see {@link #DEFAULT}).
  *
  * An <code>IllegalArgumentException</code> is thrown if the
  * <code>setdigits</code> parameter is out of range
  * (&lt;0 or &gt;999999999), or if the value given for the
  * <code>setform</code> parameter is not one of the appropriate
  * constants.
  *
  * @param setdigits     The <code>int</code> digits setting
  *                      for this <code>MathContext</code>.
  * @param setform       The <code>int</code> form setting
  *                      for this <code>MathContext</code>.
  * @param setlostdigits The <code>boolean</code> lostDigits
  *                      setting for this <code>MathContext</code>.
  * @throws IllegalArgumentException parameter out of range.
  * @stable ICU 2.0
  */

 public MathContext(int setdigits,int setform,boolean setlostdigits){
  this(setdigits,setform,setlostdigits,DEFAULT_ROUNDINGMODE);
  return;}

 /**
  * Constructs a new <code>MathContext</code> with a specified
  * precision, form, lostDigits, and roundingMode setting.
  *
  * An <code>IllegalArgumentException</code> is thrown if the
  * <code>setdigits</code> parameter is out of range
  * (&lt;0 or &gt;999999999), or if the value given for the
  * <code>setform</code> or <code>setroundingmode</code> parameters is
  * not one of the appropriate constants.
  *
  * @param setdigits       The <code>int</code> digits setting
  *                        for this <code>MathContext</code>.
  * @param setform         The <code>int</code> form setting
  *                        for this <code>MathContext</code>.
  * @param setlostdigits   The <code>boolean</code> lostDigits
  *                        setting for this <code>MathContext</code>.
  * @param setroundingmode The <code>int</code> roundingMode setting
  *                        for this <code>MathContext</code>.
  * @throws IllegalArgumentException parameter out of range.
  * @stable ICU 2.0
  */

 public MathContext(int setdigits,int setform,boolean setlostdigits,int setroundingmode){super();


  // set values, after checking
  if (setdigits!=DEFAULT_DIGITS)
   {
    if (setdigits<MIN_DIGITS)
     throw new java.lang.IllegalArgumentException("Digits too small:"+" "+setdigits);
    if (setdigits>MAX_DIGITS)
     throw new java.lang.IllegalArgumentException("Digits too large:"+" "+setdigits);
   }
  {/*select*/
  if (setform==SCIENTIFIC){
   // [most common]
  }else if (setform==ENGINEERING){
  }else if (setform==PLAIN){
  }else{
   throw new java.lang.IllegalArgumentException("Bad form value:"+" "+setform);
  }
  }
  if ((!(isValidRound(setroundingmode))))
   throw new java.lang.IllegalArgumentException("Bad roundingMode value:"+" "+setroundingmode);
  digits=setdigits;
  form=setform;
  lostDigits=setlostdigits; // [no bad value possible]
  roundingMode=setroundingmode;
  return;}

 /**
  * Returns the digits setting.
  * This value is always non-negative.
  *
  * @return an <code>int</code> which is the value of the digits
  *         setting
  * @stable ICU 2.0
  */

 public int getDigits(){
  return digits;
  }

 /**
  * Returns the form setting.
  * This will be one of
  * {@link #ENGINEERING},
  * {@link #PLAIN}, or
  * {@link #SCIENTIFIC}.
  *
  * @return an <code>int</code> which is the value of the form setting
  * @stable ICU 2.0
  */

 public int getForm(){
  return form;
  }

 /**
  * Returns the lostDigits setting.
  * This will be either <code>true</code> (enabled) or
  * <code>false</code> (disabled).
  *
  * @return a <code>boolean</code> which is the value of the lostDigits
  *           setting
  * @stable ICU 2.0
  */

 public boolean getLostDigits(){
  return lostDigits;
  }

 /**
  * Returns the roundingMode setting.
  * This will be one of
  * {@link  #ROUND_CEILING},
  * {@link  #ROUND_DOWN},
  * {@link  #ROUND_FLOOR},
  * {@link  #ROUND_HALF_DOWN},
  * {@link  #ROUND_HALF_EVEN},
  * {@link  #ROUND_HALF_UP},
  * {@link  #ROUND_UNNECESSARY}, or
  * {@link  #ROUND_UP}.
  *
  * @return an <code>int</code> which is the value of the roundingMode
  *         setting
  * @stable ICU 2.0
  */

 public int getRoundingMode(){
  return roundingMode;
  }

 /** Returns the <code>MathContext</code> as a readable string.
  * The <code>String</code> returned represents the settings of the
  * <code>MathContext</code> object as four blank-delimited words
  * separated by a single blank and with no leading or trailing blanks,
  * as follows:
  * <ol>
  * <li>
  * <code>digits=</code>, immediately followed by
  * the value of the digits setting as a numeric word.
  * <li>
  * <code>form=</code>, immediately followed by
  * the value of the form setting as an uppercase word
  * (one of <code>SCIENTIFIC</code>, <code>PLAIN</code>, or
  * <code>ENGINEERING</code>).
  * <li>
  * <code>lostDigits=</code>, immediately followed by
  * the value of the lostDigits setting
  * (<code>1</code> if enabled, <code>0</code> if disabled).
  * <li>
  * <code>roundingMode=</code>, immediately followed by
  * the value of the roundingMode setting as a word.
  * This word will be the same as the name of the corresponding public
  * constant.
  * </ol>
  * <p>
  * For example:
  * <br><code>
  * digits=9 form=SCIENTIFIC lostDigits=0 roundingMode=ROUND_HALF_UP
  * </code>
  * <p>
  * Additional words may be appended to the result of
  * <code>toString</code> in the future if more properties are added
  * to the class.
  *
  * @return a <code>String</code> representing the context settings.
  * @stable ICU 2.0
  */

 @Override
 public java.lang.String toString(){
  java.lang.String formstr=null;
  int r=0;
  java.lang.String roundword=null;
  {/*select*/
  if (form==SCIENTIFIC)
   formstr="SCIENTIFIC";
  else if (form==ENGINEERING)
   formstr="ENGINEERING";
  else{
   formstr="PLAIN";/* form=PLAIN */
  }
  }
  {int $1=ROUNDS.length;r=0;r:for(;$1>0;$1--,r++){
   if (roundingMode==ROUNDS[r])
    {
     roundword=ROUNDWORDS[r];
     break r;
    }
   }
  }/*r*/
  return "digits="+digits+" "+"form="+formstr+" "+"lostDigits="+(lostDigits?"1":"0")+" "+"roundingMode="+roundword;
  }


 /* <sgml> Test whether round is valid. </sgml> */
 // This could be made shared for use by BigDecimal for setScale.

 private static boolean isValidRound(int testround){
  int r=0;
  {int $2=ROUNDS.length;for(r=0;$2>0;$2--,r++){
   if (testround==ROUNDS[r])
    return true;
   }
  }/*r*/
  return false;
  }
 }