/* MathContext.java --
   Copyright (C) 1999, 2000, 2002, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

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General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package java.math;

import java.io.Serializable;

/**
 * Immutable objects describing settings such as rounding mode and digit
 * precision for numerical operations such as those in the BigDecimal class.
 * @author Anthony Balkissoon abalkiss at redhat dot com
 *
 */
public final class MathContext implements Serializable
{
  /** A MathContext for unlimited precision arithmetic * */
  public static final MathContext UNLIMITED =
    new MathContext(0, RoundingMode.HALF_UP);

  /**
   * A MathContext for the IEEE 754R Decimal32 format - 7 digit preicision and
   * HALF_EVEN rounding.
   */
  public static final MathContext DECIMAL32 =
    new MathContext(7, RoundingMode.HALF_EVEN);

  /**
   * A MathContext for the IEEE 754R Decimal64 format - 16 digit preicision and
   * HALF_EVEN rounding.
   */
  public static final MathContext DECIMAL64 =
    new MathContext(16, RoundingMode.HALF_EVEN);

  /**
   * A MathContext for the IEEE 754R Decimal128 format - 34 digit preicision and
   * HALF_EVEN rounding.
   */
  public static final MathContext DECIMAL128 =
    new MathContext(34, RoundingMode.HALF_EVEN);

  /**
   * This is the serialVersionUID reported here:
   * java.sun.com/j2se/1.5.0/docs/api/serialized-form.html#java.math.MathContext
   */
  private static final long serialVersionUID = 5579720004786848255L;

  private int precision;

  private RoundingMode roundMode;

  /**
   * Constructs a new MathContext with the specified precision and with HALF_UP
   * rounding.
   * @param setPrecision the precision for the new MathContext
   *
   * @throws IllegalArgumentException if precision is < 0.
   */
  public MathContext(int setPrecision)
  {
    this(setPrecision, RoundingMode.HALF_UP);
  }

  /**
   * Constructs a new MathContext with the specified precision and rounding
   * mode.
   * @param setPrecision the precision
   * @param setRoundingMode the rounding mode
   *
   * @throws IllegalArgumentException if precision is < 0.
   */
  public MathContext(int setPrecision, RoundingMode setRoundingMode)
  {
    if (setPrecision < 0)
      throw new IllegalArgumentException("Precision cannot be less than zero.");
    precision = setPrecision;
    roundMode = setRoundingMode;
  }

  /**
   * Constructs a MathContext from a String that has the same form as one
   * produced by the toString() method.
   * @param val
   *
   * @throws IllegalArgumentException if the String is not in the correct
   * format or if the precision specified is < 0.
   */
  public MathContext(String val)
  {
    try
    {
      int roundingModeIndex = val.indexOf("roundingMode", 10);
      precision = Integer.parseInt(val.substring(10, roundingModeIndex - 1));
      roundMode = RoundingMode.valueOf(val.substring(roundingModeIndex + 13));
    }
    catch (NumberFormatException nfe)
    {
      throw new IllegalArgumentException("String not in correct format");
    }
    catch (IllegalArgumentException iae)
    {
      throw new IllegalArgumentException("String not in correct format");
    }
    if (precision < 0)
      throw new IllegalArgumentException("Precision cannot be less than 0.");
  }

  /**
   * Returns true if x is a MathContext and has the same precision setting
   * and rounding mode as this MathContext.
   *
   * @return true if the above conditions hold
   */
  public boolean equals(Object x)
  {
    if (!(x instanceof MathContext))
      return false;
    MathContext mc = (MathContext)x;
    return mc.precision == this.precision
           && mc.roundMode.equals(this.roundMode);
  }

  /**
   * Returns the precision setting.
   * @return the precision setting.
   */
  public int getPrecision()
  {
    return precision;
  }

  /**
   * Returns the rounding mode setting.  This will be one of
   * RoundingMode.CEILING, RoundingMode.DOWN, RoundingMode.FLOOR,
   * RoundingMode.HALF_DOWN, RoundingMode.HALF_EVEN, RoundingMode.HALF_UP,
   * RoundingMode.UNNECESSARY, or RoundingMode.UP.
   * @return the rounding mode setting.
   */
  public RoundingMode getRoundingMode()
  {
    return roundMode;
  }

  /**
   * Returns "precision=p roundingMode=MODE" where p is an int giving the
   * precision and MODE is UP, DOWN, HALF_UP, HALF_DOWN, HALF_EVEN, CEILING,
   * FLOOR, or UNNECESSARY corresponding to rounding modes.
   *
   * @return a String describing this MathContext
   */
  public String toString()
  {
    return "precision="+precision+" roundingMode="+roundMode;
  }

  /**
   * Returns the hashcode for this MathContext.
   * @return the hashcode for this MathContext.
   */
  public int hashCode()
  {
    return precision ^ roundMode.hashCode();
  }
}