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 35816 2004-05-06 03:47:48Z fdrake $

    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]