[2674] | 1 | /* |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
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| 3 | * contributor license agreements. See the NOTICE file distributed with |
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| 4 | * this work for additional information regarding copyright ownership. |
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| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
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| 6 | * (the "License"); you may not use this file except in compliance with |
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| 7 | * the License. You may obtain a copy of the License at |
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| 8 | * |
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| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 10 | * |
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| 11 | * Unless required by applicable law or agreed to in writing, software |
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| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 14 | * See the License for the specific language governing permissions and |
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| 15 | * limitations under the License. |
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| 16 | */ |
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| 17 | |
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| 18 | /* |
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| 19 | * $Id: EntityResolver.hpp 568078 2007-08-21 11:43:25Z amassari $ |
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| 20 | */ |
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| 21 | |
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| 22 | |
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| 23 | #ifndef ENTITYRESOLVER_HPP |
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| 24 | #define ENTITYRESOLVER_HPP |
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| 25 | |
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| 26 | #include <xercesc/util/XercesDefs.hpp> |
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| 27 | |
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| 28 | XERCES_CPP_NAMESPACE_BEGIN |
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| 29 | |
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| 30 | class InputSource; |
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| 31 | |
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| 32 | /** |
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| 33 | * Basic interface for resolving entities. |
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| 34 | * |
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| 35 | * <p>If a SAX application needs to implement customized handling |
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| 36 | * for external entities, it must implement this interface and |
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| 37 | * register an instance with the SAX parser using the parser's |
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| 38 | * setEntityResolver method.</p> |
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| 39 | * |
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| 40 | * <p>The parser will then allow the application to intercept any |
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| 41 | * external entities (including the external DTD subset and external |
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| 42 | * parameter entities, if any) before including them.</p> |
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| 43 | * |
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| 44 | * <p>Many SAX applications will not need to implement this interface, |
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| 45 | * but it will be especially useful for applications that build |
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| 46 | * XML documents from databases or other specialised input sources, |
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| 47 | * or for applications that use URI types other than URLs.</p> |
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| 48 | * |
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| 49 | * <p>The following resolver would provide the application |
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| 50 | * with a special character stream for the entity with the system |
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| 51 | * identifier "http://www.myhost.com/today":</p> |
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| 52 | * |
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| 53 | *<code> |
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| 54 | *#include <xercesc/sax/EntityResolver.hpp><br> |
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| 55 | *#include <xercesc/sax/InputSource.hpp><br> |
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| 56 | *<br> |
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| 57 | *class MyResolver : public EntityResolver {<br> |
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| 58 | * public:<br> |
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| 59 | * InputSource resolveEntity (const XMLCh* const publicId, const XMLCh* const systemId);<br> |
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| 60 | * <br> |
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| 61 | * ...<br> |
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| 62 | * };<br> |
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| 63 | *<br> |
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| 64 | * MyResolver::resolveEntity {<br> |
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| 65 | * if (XMLString::compareString(systemId, "http://www.myhost.com/today")) {<br> |
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| 66 | * MyReader* reader = new MyReader();<br> |
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| 67 | * return new InputSource(reader);<br> |
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| 68 | * } else {<br> |
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| 69 | * return null;<br> |
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| 70 | * }<br> |
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| 71 | * }<br> |
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| 72 | *<br> |
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| 73 | *</code> |
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| 74 | * |
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| 75 | * <p>The application can also use this interface to redirect system |
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| 76 | * identifiers to local URIs or to look up replacements in a catalog |
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| 77 | * (possibly by using the public identifier).</p> |
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| 78 | * |
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| 79 | * <p>The HandlerBase class implements the default behaviour for |
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| 80 | * this interface, which is simply always to return null (to request |
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| 81 | * that the parser use the default system identifier).</p> |
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| 82 | * |
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| 83 | * @see Parser#setEntityResolver |
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| 84 | * @see InputSource#InputSource |
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| 85 | * @see HandlerBase#HandlerBase |
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| 86 | */ |
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| 87 | class SAX_EXPORT EntityResolver |
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| 88 | { |
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| 89 | public: |
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| 90 | /** @name Constructors and Destructor */ |
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| 91 | //@{ |
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| 92 | |
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| 93 | /** Default Constructor */ |
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| 94 | EntityResolver() |
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| 95 | { |
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| 96 | } |
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| 97 | |
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| 98 | /** Destructor */ |
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| 99 | virtual ~EntityResolver() |
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| 100 | { |
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| 101 | } |
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| 102 | |
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| 103 | //@} |
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| 104 | |
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| 105 | /** @name The EntityResolver interface */ |
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| 106 | //@{ |
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| 107 | |
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| 108 | /** |
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| 109 | * Allow the application to resolve external entities. |
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| 110 | * |
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| 111 | * <p>The Parser will call this method before opening any external |
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| 112 | * entity except the top-level document entity (including the |
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| 113 | * external DTD subset, external entities referenced within the |
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| 114 | * DTD, and external entities referenced within the document |
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| 115 | * element): the application may request that the parser resolve |
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| 116 | * the entity itself, that it use an alternative URI, or that it |
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| 117 | * use an entirely different input source.</p> |
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| 118 | * |
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| 119 | * <p>Application writers can use this method to redirect external |
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| 120 | * system identifiers to secure and/or local URIs, to look up |
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| 121 | * public identifiers in a catalogue, or to read an entity from a |
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| 122 | * database or other input source (including, for example, a dialog |
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| 123 | * box).</p> |
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| 124 | * |
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| 125 | * <p>If the system identifier is a URL, the SAX parser must |
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| 126 | * resolve it fully before reporting it to the application.</p> |
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| 127 | * |
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| 128 | * @param publicId The public identifier of the external entity |
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| 129 | * being referenced, or null if none was supplied. |
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| 130 | * @param systemId The system identifier of the external entity |
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| 131 | * being referenced. |
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| 132 | * @return An InputSource object describing the new input source, |
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| 133 | * or null to request that the parser open a regular |
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| 134 | * URI connection to the system identifier. |
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| 135 | * The returned InputSource is owned by the parser which is |
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| 136 | * responsible to clean up the memory. |
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| 137 | * @exception SAXException Any SAX exception, possibly |
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| 138 | * wrapping another exception. |
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| 139 | * @exception IOException An IO exception, |
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| 140 | * possibly the result of creating a new InputStream |
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| 141 | * or Reader for the InputSource. |
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| 142 | * @see InputSource#InputSource |
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| 143 | */ |
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| 144 | virtual InputSource* resolveEntity |
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| 145 | ( |
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| 146 | const XMLCh* const publicId |
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| 147 | , const XMLCh* const systemId |
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| 148 | ) = 0; |
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| 149 | |
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| 150 | //@} |
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| 151 | |
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| 152 | private : |
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| 153 | /* Unimplemented constructors and operators */ |
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| 154 | |
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| 155 | |
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| 156 | /* Copy constructor */ |
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| 157 | EntityResolver(const EntityResolver&); |
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| 158 | |
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| 159 | /* Assignment operator */ |
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| 160 | EntityResolver& operator=(const EntityResolver&); |
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| 161 | |
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| 162 | }; |
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| 163 | |
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| 164 | XERCES_CPP_NAMESPACE_END |
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| 165 | |
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| 166 | #endif |
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