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 gnu.java.lang.CPStringBuilder;
  41
  42 import javax.xml.namespace.QName;
  43 import org.w3c.dom.Node;
  44
  45 /**
  46  * Binary arithmetic expression.
  47  *
  48  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  49  */
  50 final class ArithmeticExpr
  51   extends Expr
  52 {
  53
  54   static final int ADD = 0;
  55   static final int SUBTRACT = 1;
  56   static final int MULTIPLY = 2;
  57   static final int DIVIDE = 3;
  58   static final int MODULO = 4;
  59
  60   final Expr lhs;
  61   final Expr rhs;
  62   final int op;
  63
  64   ArithmeticExpr(Expr lhs, Expr rhs, int op)
  65   {
  66     this.lhs = lhs;
  67     this.rhs = rhs;
  68     switch (op)
  69       {
  70       case ADD:
  71       case SUBTRACT:
  72       case MULTIPLY:
  73       case DIVIDE:
  74       case MODULO:
  75                                 this.op = op;
  76                                 break;
  77       default:
  78         throw new IllegalArgumentException();
  79       }
  80   }
  81
  82   public Object evaluate(Node context, int pos, int len)
  83   {
  84     Object left = lhs.evaluate(context, pos, len);
  85     Object right = rhs.evaluate(context, pos, len);
  86
  87     double ln = _number(context, left);
  88     double rn = _number(context, right);
  89     switch (op)
  90       {
  91       case ADD:
  92         return new Double(ln + rn);
  93       case SUBTRACT:
  94         return new Double(ln - rn);
  95       case MULTIPLY:
  96         return new Double(ln * rn);
  97       case DIVIDE:
  98         if (rn == 0.0d || rn == -0.0d)
  99           {
 100             if (ln == 0.0d || ln == -0.0d)
 101               {
 102                 return new Double(Double.NaN);
 103               }
 104             else
 105               {
 106                 return new Double(ln < 0.0d ?
 107                                   Double.NEGATIVE_INFINITY :
 108                                   Double.POSITIVE_INFINITY);
 109               }
 110           }
 111         return new Double(ln / rn);
 112       case MODULO:
 113         if (rn == 0.0d || rn == 0.0d)
 114           {
 115             if (ln == 0.0d || ln == -0.0d)
 116               {
 117                 return new Double(Double.NaN);
 118               }
 119             else
 120               {
 121                 return new Double(ln < 0.0d ?
 122                                   Double.NEGATIVE_INFINITY :
 123                                   Double.POSITIVE_INFINITY);
 124               }
 125           }
 126         return new Double(ln % rn);
 127       default:
 128         throw new IllegalStateException();
 129       }
 130   }
 131
 132   public Expr clone(Object context)
 133   {
 134     return new ArithmeticExpr(lhs.clone(context), rhs.clone(context), op);
 135   }
 136
 137   public boolean references(QName var)
 138   {
 139     return (lhs.references(var) || rhs.references(var));
 140   }
 141
 142   public String toString()
 143   {
 144     CPStringBuilder buf = new CPStringBuilder();
 145     buf.append(lhs);
 146     buf.append(' ');
 147     switch (op)
 148       {
 149       case ADD:
 150         buf.append('+');
 151         break;
 152       case SUBTRACT:
 153         buf.append('-');
 154         break;
 155       case MULTIPLY:
 156         buf.append('*');
 157         break;
 158       case DIVIDE:
 159         buf.append("div");
 160         break;
 161       case MODULO:
 162         buf.append("mod");
 163         break;
 164       }
 165     buf.append(' ');
 166     buf.append(rhs);
 167     return buf.toString();
 168   }
 169
 170 }