1 """ 2 This module contains the core classes of version 2.0 of SAX for Python. 3 This file provides only default classes with absolutely minimum 4 functionality, from which drivers and applications can be subclassed. 5 6 Many of these classes are empty and are included only as documentation 7 of the interfaces. 8 9 $Id$ 10 """ 11 12 version = '2.0beta' 13 14 #============================================================================ 15 # 16 # HANDLER INTERFACES 17 # 18 #============================================================================ 19 20 # ===== ERRORHANDLER ===== 21 22 class ErrorHandler: 23 """Basic interface for SAX error handlers. 24 25 If you create an object that implements this interface, then 26 register the object with your XMLReader, the parser will call the 27 methods in your object to report all warnings and errors. There 28 are three levels of errors available: warnings, (possibly) 29 recoverable errors, and unrecoverable errors. All methods take a 30 SAXParseException as the only parameter.""" 31 32 def error(self, exception): 33 "Handle a recoverable error." 34 raise exception 35 36 def fatalError(self, exception): 37 "Handle a non-recoverable error." 38 raise exception 39 40 def warning(self, exception): 41 "Handle a warning." 42 print exception 43 44 45 # ===== CONTENTHANDLER ===== 46 47 class ContentHandler: 48 """Interface for receiving logical document content events. 49 50 This is the main callback interface in SAX, and the one most 51 important to applications. The order of events in this interface 52 mirrors the order of the information in the document.""" 53 54 def __init__(self): 55 self._locator = None 56 57 def setDocumentLocator(self, locator): 58 """Called by the parser to give the application a locator for 59 locating the origin of document events. 60 61 SAX parsers are strongly encouraged (though not absolutely 62 required) to supply a locator: if it does so, it must supply 63 the locator to the application by invoking this method before 64 invoking any of the other methods in the DocumentHandler 65 interface. 66 67 The locator allows the application to determine the end 68 position of any document-related event, even if the parser is 69 not reporting an error. Typically, the application will use 70 this information for reporting its own errors (such as 71 character content that does not match an application's 72 business rules). The information returned by the locator is 73 probably not sufficient for use with a search engine. 74 75 Note that the locator will return correct information only 76 during the invocation of the events in this interface. The 77 application should not attempt to use it at any other time.""" 78 self._locator = locator 79 80 def startDocument(self): 81 """Receive notification of the beginning of a document. 82 83 The SAX parser will invoke this method only once, before any 84 other methods in this interface or in DTDHandler (except for 85 setDocumentLocator).""" 86 87 def endDocument(self): 88 """Receive notification of the end of a document. 89 90 The SAX parser will invoke this method only once, and it will 91 be the last method invoked during the parse. The parser shall 92 not invoke this method until it has either abandoned parsing 93 (because of an unrecoverable error) or reached the end of 94 input.""" 95 96 def startPrefixMapping(self, prefix, uri): 97 """Begin the scope of a prefix-URI Namespace mapping. 98 99 The information from this event is not necessary for normal 100 Namespace processing: the SAX XML reader will automatically 101 replace prefixes for element and attribute names when the 102 http://xml.org/sax/features/namespaces feature is true (the 103 default). 104 105 There are cases, however, when applications need to use 106 prefixes in character data or in attribute values, where they 107 cannot safely be expanded automatically; the 108 start/endPrefixMapping event supplies the information to the 109 application to expand prefixes in those contexts itself, if 110 necessary. 111 112 Note that start/endPrefixMapping events are not guaranteed to 113 be properly nested relative to each-other: all 114 startPrefixMapping events will occur before the corresponding 115 startElement event, and all endPrefixMapping events will occur 116 after the corresponding endElement event, but their order is 117 not guaranteed.""" 118 119 def endPrefixMapping(self, prefix): 120 """End the scope of a prefix-URI mapping. 121 122 See startPrefixMapping for details. This event will always 123 occur after the corresponding endElement event, but the order 124 of endPrefixMapping events is not otherwise guaranteed.""" 125 126 def startElement(self, name, attrs): 127 """Signals the start of an element in non-namespace mode. 128 129 The name parameter contains the raw XML 1.0 name of the 130 element type as a string and the attrs parameter holds an 131 instance of the Attributes class containing the attributes of 132 the element.""" 133 134 def endElement(self, name): 135 """Signals the end of an element in non-namespace mode. 136 137 The name parameter contains the name of the element type, just 138 as with the startElement event.""" 139 140 def startElementNS(self, name, qname, attrs): 141 """Signals the start of an element in namespace mode. 142 143 The name parameter contains the name of the element type as a 144 (uri, localname) tuple, the qname parameter the raw XML 1.0 145 name used in the source document, and the attrs parameter 146 holds an instance of the Attributes class containing the 147 attributes of the element. 148 149 The uri part of the name tuple is None for elements which have 150 no namespace.""" 151 152 def endElementNS(self, name, qname): 153 """Signals the end of an element in namespace mode. 154 155 The name parameter contains the name of the element type, just 156 as with the startElementNS event.""" 157 158 def characters(self, content): 159 """Receive notification of character data. 160 161 The Parser will call this method to report each chunk of 162 character data. SAX parsers may return all contiguous 163 character data in a single chunk, or they may split it into 164 several chunks; however, all of the characters in any single 165 event must come from the same external entity so that the 166 Locator provides useful information.""" 167 168 def ignorableWhitespace(self, whitespace): 169 """Receive notification of ignorable whitespace in element content. 170 171 Validating Parsers must use this method to report each chunk 172 of ignorable whitespace (see the W3C XML 1.0 recommendation, 173 section 2.10): non-validating parsers may also use this method 174 if they are capable of parsing and using content models. 175 176 SAX parsers may return all contiguous whitespace in a single 177 chunk, or they may split it into several chunks; however, all 178 of the characters in any single event must come from the same 179 external entity, so that the Locator provides useful 180 information.""" 181 182 def processingInstruction(self, target, data): 183 """Receive notification of a processing instruction. 184 185 The Parser will invoke this method once for each processing 186 instruction found: note that processing instructions may occur 187 before or after the main document element. 188 189 A SAX parser should never report an XML declaration (XML 1.0, 190 section 2.8) or a text declaration (XML 1.0, section 4.3.1) 191 using this method.""" 192 193 def skippedEntity(self, name): 194 """Receive notification of a skipped entity. 195 196 The Parser will invoke this method once for each entity 197 skipped. Non-validating processors may skip entities if they 198 have not seen the declarations (because, for example, the 199 entity was declared in an external DTD subset). All processors 200 may skip external entities, depending on the values of the 201 http://xml.org/sax/features/external-general-entities and the 202 http://xml.org/sax/features/external-parameter-entities 203 properties.""" 204 205 206 # ===== DTDHandler ===== 207 208 class DTDHandler: 209 """Handle DTD events. 210 211 This interface specifies only those DTD events required for basic 212 parsing (unparsed entities and attributes).""" 213 214 def notationDecl(self, name, publicId, systemId): 215 "Handle a notation declaration event." 216 217 def unparsedEntityDecl(self, name, publicId, systemId, ndata): 218 "Handle an unparsed entity declaration event." 219 220 221 # ===== ENTITYRESOLVER ===== 222 223 class EntityResolver: 224 """Basic interface for resolving entities. If you create an object 225 implementing this interface, then register the object with your 226 Parser, the parser will call the method in your object to 227 resolve all external entities. Note that DefaultHandler implements 228 this interface with the default behaviour.""" 229 230 def resolveEntity(self, publicId, systemId): 231 """Resolve the system identifier of an entity and return either 232 the system identifier to read from as a string, or an InputSource 233 to read from.""" 234 return systemId 235 236 237 #============================================================================ 238 # 239 # CORE FEATURES 240 # 241 #============================================================================ 242 243 feature_namespaces = "http://xml.org/sax/features/namespaces" 244 # true: Perform Namespace processing (default). 245 # false: Optionally do not perform Namespace processing 246 # (implies namespace-prefixes). 247 # access: (parsing) read-only; (not parsing) read/write 248 249 feature_namespace_prefixes = "http://xml.org/sax/features/namespace-prefixes" 250 # true: Report the original prefixed names and attributes used for Namespace 251 # declarations. 252 # false: Do not report attributes used for Namespace declarations, and 253 # optionally do not report original prefixed names (default). 254 # access: (parsing) read-only; (not parsing) read/write 255 256 feature_string_interning = "http://xml.org/sax/features/string-interning" 257 # true: All element names, prefixes, attribute names, Namespace URIs, and 258 # local names are interned using the built-in intern function. 259 # false: Names are not necessarily interned, although they may be (default). 260 # access: (parsing) read-only; (not parsing) read/write 261 262 feature_validation = "http://xml.org/sax/features/validation" 263 # true: Report all validation errors (implies external-general-entities and 264 # external-parameter-entities). 265 # false: Do not report validation errors. 266 # access: (parsing) read-only; (not parsing) read/write 267 268 feature_external_ges = "http://xml.org/sax/features/external-general-entities" 269 # true: Include all external general (text) entities. 270 # false: Do not include external general entities. 271 # access: (parsing) read-only; (not parsing) read/write 272 273 feature_external_pes = "http://xml.org/sax/features/external-parameter-entities" 274 # true: Include all external parameter entities, including the external 275 # DTD subset. 276 # false: Do not include any external parameter entities, even the external 277 # DTD subset. 278 # access: (parsing) read-only; (not parsing) read/write 279 280 all_features = [feature_namespaces, 281 feature_namespace_prefixes, 282 feature_string_interning, 283 feature_validation, 284 feature_external_ges, 285 feature_external_pes] 286 287 288 #============================================================================ 289 # 290 # CORE PROPERTIES 291 # 292 #============================================================================ 293 294 property_lexical_handler = "http://xml.org/sax/properties/lexical-handler" 295 # data type: xml.sax.sax2lib.LexicalHandler 296 # description: An optional extension handler for lexical events like comments. 297 # access: read/write 298 299 property_declaration_handler = "http://xml.org/sax/properties/declaration-handler" 300 # data type: xml.sax.sax2lib.DeclHandler 301 # description: An optional extension handler for DTD-related events other 302 # than notations and unparsed entities. 303 # access: read/write 304 305 property_dom_node = "http://xml.org/sax/properties/dom-node" 306 # data type: org.w3c.dom.Node 307 # description: When parsing, the current DOM node being visited if this is 308 # a DOM iterator; when not parsing, the root DOM node for 309 # iteration. 310 # access: (parsing) read-only; (not parsing) read/write 311 312 property_xml_string = "http://xml.org/sax/properties/xml-string" 313 # data type: String 314 # description: The literal string of characters that was the source for 315 # the current event. 316 # access: read-only 317 318 property_encoding = "http://www.python.org/sax/properties/encoding" 319 # data type: String 320 # description: The name of the encoding to assume for input data. 321 # access: write: set the encoding, e.g. established by a higher-level 322 # protocol. May change during parsing (e.g. after 323 # processing a META tag) 324 # read: return the current encoding (possibly established through 325 # auto-detection. 326 # initial value: UTF-8 327 # 328 329 property_interning_dict = "http://www.python.org/sax/properties/interning-dict" 330 # data type: Dictionary 331 # description: The dictionary used to intern common strings in the document 332 # access: write: Request that the parser uses a specific dictionary, to 333 # allow interning across different documents 334 # read: return the current interning dictionary, or None 335 # 336 337 all_properties = [property_lexical_handler, 338 property_dom_node, 339 property_declaration_handler, 340 property_xml_string, 341 property_encoding, 342 property_interning_dict] 343
