1 /*
   2  * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.xml.internal.dtdparser;
  27 
  28 
  29 /**
  30  * This class contains static methods used to determine whether identifiers
  31  * may appear in certain roles in XML documents.  Such methods are used
  32  * both to parse and to create such documents.
  33  *
  34  * @author David Brownell
  35  * @version 1.1, 00/08/05
  36  */
  37 public class XmlNames {
  38     private XmlNames() {
  39     }
  40 
  41 
  42     /**
  43      * Returns true if the value is a legal XML name.
  44      *
  45      * @param value the string being tested
  46      */
  47     public static boolean isName(String value) {
  48         if (value == null)
  49             return false;
  50 
  51         char c = value.charAt(0);
  52         if (!XmlChars.isLetter(c) && c != '_' && c != ':')
  53             return false;
  54         for (int i = 1; i < value.length(); i++)
  55             if (!XmlChars.isNameChar(value.charAt(i)))
  56                 return false;
  57         return true;
  58     }
  59 
  60     /**
  61      * Returns true if the value is a legal "unqualified" XML name, as
  62      * defined in the XML Namespaces proposed recommendation.
  63      * These are normal XML names, except that they may not contain
  64      * a "colon" character.
  65      *
  66      * @param value the string being tested
  67      */
  68     public static boolean isUnqualifiedName(String value) {
  69         if (value == null || value.length() == 0)
  70             return false;
  71 
  72         char c = value.charAt(0);
  73         if (!XmlChars.isLetter(c) && c != '_')
  74             return false;
  75         for (int i = 1; i < value.length(); i++)
  76             if (!XmlChars.isNCNameChar(value.charAt(i)))
  77                 return false;
  78         return true;
  79     }
  80 
  81     /**
  82      * Returns true if the value is a legal "qualified" XML name, as defined
  83      * in the XML Namespaces proposed recommendation.  Qualified names are
  84      * composed of an optional prefix (an unqualified name), followed by a
  85      * colon, and a required "local part" (an unqualified name).  Prefixes are
  86      * declared, and correspond to particular URIs which scope the "local
  87      * part" of the name.  (This method cannot check whether the prefix of a
  88      * name has been declared.)
  89      *
  90      * @param value the string being tested
  91      */
  92     public static boolean isQualifiedName(String value) {
  93         if (value == null)
  94             return false;
  95 
  96         // [6] QName ::= (Prefix ':')? LocalPart
  97         // [7] Prefix ::= NCName
  98         // [8] LocalPart ::= NCName
  99 
 100         int first = value.indexOf(':');
 101 
 102         // no Prefix, only check LocalPart
 103         if (first <= 0)
 104             return isUnqualifiedName(value);
 105 
 106         // Prefix exists, check everything
 107 
 108         int last = value.lastIndexOf(':');
 109         if (last != first)
 110             return false;
 111 
 112         return isUnqualifiedName(value.substring(0, first))
 113                 && isUnqualifiedName(value.substring(first + 1));
 114     }
 115 
 116     /**
 117      * This method returns true if the identifier is a "name token"
 118      * as defined in the XML specification.  Like names, these
 119      * may only contain "name characters"; however, they do not need
 120      * to have letters as their initial characters.  Attribute values
 121      * defined to be of type NMTOKEN(S) must satisfy this predicate.
 122      *
 123      * @param token the string being tested
 124      */
 125     public static boolean isNmtoken(String token) {
 126         int length = token.length();
 127 
 128         for (int i = 0; i < length; i++)
 129             if (!XmlChars.isNameChar(token.charAt(i)))
 130                 return false;
 131         return true;
 132     }
 133 
 134 
 135     /**
 136      * This method returns true if the identifier is a "name token" as
 137      * defined by the XML Namespaces proposed recommendation.
 138      * These are like XML "name tokens" but they may not contain the
 139      * "colon" character.
 140      *
 141      * @param token the string being tested
 142      * @see #isNmtoken
 143      */
 144     public static boolean isNCNmtoken(String token) {
 145         return isNmtoken(token) && token.indexOf(':') < 0;
 146     }
 147 }