gomp-20050608-branch/libjava/classpath/gnu/xml/xpath/ArithmeticExpr.java

   1 /* ArithmeticExpr.java --
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package gnu.xml.xpath;
  39
  40 import javax.xml.namespace.QName;
  41 import org.w3c.dom.Node;
  42
  43 /**
  44  * Binary arithmetic expression.
  45  *
  46  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  47  */
  48 final class ArithmeticExpr
  49   extends Expr
  50 {
  51
  52   static final int ADD = 0;
  53   static final int SUBTRACT = 1;
  54   static final int MULTIPLY = 2;
  55   static final int DIVIDE = 3;
  56   static final int MODULO = 4;
  57
  58   final Expr lhs;
  59   final Expr rhs;
  60   final int op;
  61
  62   ArithmeticExpr(Expr lhs, Expr rhs, int op)
  63   {
  64     this.lhs = lhs;
  65     this.rhs = rhs;
  66     switch (op)
  67       {
  68       case ADD:
  69       case SUBTRACT:
  70       case MULTIPLY:
  71       case DIVIDE:
  72       case MODULO:
  73                                 this.op = op;
  74                                 break;
  75       default:
  76         throw new IllegalArgumentException();
  77       }
  78   }
  79
  80   public Object evaluate(Node context, int pos, int len)
  81   {
  82     Object left = lhs.evaluate(context, pos, len);
  83     Object right = rhs.evaluate(context, pos, len);
  84
  85     double ln = _number(context, left);
  86     double rn = _number(context, right);
  87     switch (op)
  88       {
  89       case ADD:
  90         return new Double(ln + rn);
  91       case SUBTRACT:
  92         return new Double(ln - rn);
  93       case MULTIPLY:
  94         return new Double(ln * rn);
  95       case DIVIDE:
  96         if (rn == 0.0d || rn == -0.0d)
  97           {
  98             if (ln == 0.0d || ln == -0.0d)
  99               {
 100                 return new Double(Double.NaN);
 101               }
 102             else
 103               {
 104                 return new Double(ln < 0.0d ?
 105                                   Double.NEGATIVE_INFINITY :
 106                                   Double.POSITIVE_INFINITY);
 107               }
 108           }
 109         return new Double(ln / rn);
 110       case MODULO:
 111         if (rn == 0.0d || rn == 0.0d)
 112           {
 113             if (ln == 0.0d || ln == -0.0d)
 114               {
 115                 return new Double(Double.NaN);
 116               }
 117             else
 118               {
 119                 return new Double(ln < 0.0d ?
 120                                   Double.NEGATIVE_INFINITY :
 121                                   Double.POSITIVE_INFINITY);
 122               }
 123           }
 124         return new Double(ln % rn);
 125       default:
 126         throw new IllegalStateException();
 127       }
 128   }
 129
 130   public Expr clone(Object context)
 131   {
 132     return new ArithmeticExpr(lhs.clone(context), rhs.clone(context), op);
 133   }
 134
 135   public boolean references(QName var)
 136   {
 137     return (lhs.references(var) || rhs.references(var));
 138   }
 139
 140   public String toString()
 141   {
 142     StringBuffer buf = new StringBuffer();
 143     buf.append(lhs);
 144     buf.append(' ');
 145     switch (op)
 146       {
 147       case ADD:
 148         buf.append('+');
 149         break;
 150       case SUBTRACT:
 151         buf.append('-');
 152         break;
 153       case MULTIPLY:
 154         buf.append('*');
 155         break;
 156       case DIVIDE:
 157         buf.append("div");
 158         break;
 159       case MODULO:
 160         buf.append("mod");
 161         break;
 162       }
 163     buf.append(' ');
 164     buf.append(rhs);
 165     return buf.toString();
 166   }
 167
 168 }