BigDecimalMath


1   package org.codehaus.groovy.runtime;
2   
3   import java.math.BigDecimal  ;
4   
5   /**
6    * BigDecimal NumberMath operations
7    * 
8    * @author Steve Goetze
9    */
10  public class BigDecimalMath extends NumberMath {
11  
12      //This is an arbitrary value, picked as a reasonable choice for a rounding point
13      //for typical user math.
14      public static final int MAX_DIVISION_SCALE = 10;
15      
16      protected static BigDecimalMath instance = new BigDecimalMath();
17      
18      private BigDecimalMath() {}
19  
20      protected Number   absImpl(Number   number) {
21          return toBigDecimal(number).abs();
22      }
23      
24      protected Number   addImpl(Number   left, Number   right) {
25          return toBigDecimal(left).add(toBigDecimal(right));
26      }
27  
28      protected Number   subtractImpl(Number   left, Number   right) {
29          return toBigDecimal(left).subtract(toBigDecimal(right));
30      }
31  
32      protected Number   multiplyImpl(Number   left, Number   right) {
33          return toBigDecimal(left).multiply(toBigDecimal(right));
34      }
35  
36      protected Number   divideImpl(Number   left, Number   right) {
37          //Hack until Java 1.5 BigDecimal is available.  For now, pick
38          //a result scale which is the maximum of the scale of the
39          //two operands and an arbitrary maximum (similar to what a
40          //handheld calculator would do).  Then, normalize the result
41          //by removing any trailing zeros.
42          BigDecimal   bigLeft = toBigDecimal(left);
43          BigDecimal   bigRight = toBigDecimal(right);
44          int scale = Math.max(bigLeft.scale(), bigRight.scale());
45          return normalize(bigLeft.divide(bigRight, Math.max(scale, MAX_DIVISION_SCALE), BigDecimal.ROUND_HALF_UP));
46      }
47      
48      protected int compareToImpl(Number   left, Number   right) {
49          return toBigDecimal(left).compareTo(toBigDecimal(right));
50      }
51      
52      private BigDecimal   normalize(BigDecimal   number) {
53          try {
54              while (true) {
55                  number = number.setScale(number.scale()-1);
56              } 
57          } catch (ArithmeticException   e) {
58              return number;
59          }
60      }
61  
62      protected Number   negateImpl(Number   left) {
63          return toBigDecimal(left).negate();
64      }
65  }
66
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