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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: handler.py,v 1.11 2004/05/06 03:47:48 fdrake Exp $ | |
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] |