libjava/classpath/gnu/xml/xpath/StringFunction.java

   1 /* StringFunction.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 java.util.List;
  41 import javax.xml.namespace.QName;
  42 import org.w3c.dom.Node;
  43
  44 /**
  45  * The <code>string function converts an object to a string as follows:
  46  * <ul>
  47  * <li>A node-set is converted to a string by returning the string-value of
  48  * the node in the node-set that is first in document order. If the node-set
  49  * is empty, an empty string is returned.</li>
  50  * <li>A number is converted to a string as follows
  51  * <ul>
  52  * <li>NaN is converted to the string NaN</li>
  53  * <li>positive zero is converted to the string 0</li>
  54  * <li>negative zero is converted to the string 0</li>
  55  * <li>positive infinity is converted to the string Infinity</li>
  56  * <li>negative infinity is converted to the string -Infinity</li>
  57  * <li>if the number is an integer, the number is represented in decimal
  58  * form as a Number with no decimal point and no leading zeros, preceded by
  59  * a minus sign (-) if the number is negative</li>
  60  * <li>otherwise, the number is represented in decimal form as a Number
  61  * including a decimal point with at least one digit before the decimal
  62  * point and at least one digit after the decimal point, preceded by a minus
  63  * sign (-) if the number is negative; there must be no leading zeros before
  64  * the decimal point apart possibly from the one required digit immediately
  65  * before the decimal point; beyond the one required digit after the decimal
  66  * point there must be as many, but only as many, more digits as are needed
  67  * to uniquely distinguish the number from all other IEEE 754 numeric
  68  * values.</li>
  69  * </ul>
  70  * </li>
  71  * <li>The boolean false value is converted to the string false. The boolean
  72  * true value is converted to the string true.</li>
  73  * <li>An object of a type other than the four basic types is converted to a
  74  * string in a way that is dependent on that type.</li>
  75  * </ul>
  76  * If the argument is omitted, it defaults to a node-set with the context
  77  * node as its only member.
  78  *
  79  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  80  */
  81 final class StringFunction
  82   extends Expr
  83 {
  84
  85   final Expr arg;
  86
  87   StringFunction(List<Expr> args)
  88   {
  89     this(args.size() > 0 ? args.get(0) : null);
  90   }
  91
  92   StringFunction(Expr arg)
  93   {
  94     this.arg = arg;
  95   }
  96
  97   public Object evaluate(Node context, int pos, int len)
  98   {
  99     Object val = (arg == null) ? null : arg.evaluate(context, pos, len);
 100     return _string(context, val);
 101   }
 102
 103   public Expr clone(Object context)
 104   {
 105     return new StringFunction((arg == null) ? null :
 106                               arg.clone(context));
 107   }
 108
 109   public boolean references(QName var)
 110   {
 111     return (arg == null) ? false : arg.references(var);
 112   }
 113
 114   public String toString()
 115   {
 116     return (arg == null) ? "string()" : "string(" + arg + ")";
 117   }
 118
 119 }