"""

This module contains the core classes of version 2.0 of SAX for Python.

This file provides only default classes with absolutely minimum

functionality, from which drivers and applications can be subclassed.

Many of these classes are empty and are included only as documentation

of the interfaces.

$Id: handler.py 35816 2004-05-06 03:47:48Z fdrake $

"""

version = '2.0beta'

#============================================================================

#

# HANDLER INTERFACES

#

#============================================================================

# ===== ERRORHANDLER =====

class ErrorHandler:

    """Basic interface for SAX error handlers.

    If you create an object that implements this interface, then

    register the object with your XMLReader, the parser will call the

    methods in your object to report all warnings and errors. There

    are three levels of errors available: warnings, (possibly)

    recoverable errors, and unrecoverable errors. All methods take a

    SAXParseException as the only parameter."""

    def error(self, exception):

        "Handle a recoverable error."

        raise exception

    def fatalError(self, exception):

        "Handle a non-recoverable error."

        raise exception

    def warning(self, exception):

        "Handle a warning."

        print exception

# ===== CONTENTHANDLER =====

class ContentHandler:

    """Interface for receiving logical document content events.

    This is the main callback interface in SAX, and the one most

    important to applications. The order of events in this interface

    mirrors the order of the information in the document."""

    def __init__(self):

        self._locator = None

    def setDocumentLocator(self, locator):

        """Called by the parser to give the application a locator for

        locating the origin of document events.

        SAX parsers are strongly encouraged (though not absolutely

        required) to supply a locator: if it does so, it must supply

        the locator to the application by invoking this method before

        invoking any of the other methods in the DocumentHandler

        interface.

        The locator allows the application to determine the end

        position of any document-related event, even if the parser is

        not reporting an error. Typically, the application will use

        this information for reporting its own errors (such as

        character content that does not match an application's

        business rules). The information returned by the locator is

        probably not sufficient for use with a search engine.

        Note that the locator will return correct information only

        during the invocation of the events in this interface. The

        application should not attempt to use it at any other time."""

        self._locator = locator

    def startDocument(self):

        """Receive notification of the beginning of a document.

        The SAX parser will invoke this method only once, before any

        other methods in this interface or in DTDHandler (except for

        setDocumentLocator)."""

    def endDocument(self):

        """Receive notification of the end of a document.

        The SAX parser will invoke this method only once, and it will

        be the last method invoked during the parse. The parser shall

        not invoke this method until it has either abandoned parsing

        (because of an unrecoverable error) or reached the end of

        input."""

    def startPrefixMapping(self, prefix, uri):

        """Begin the scope of a prefix-URI Namespace mapping.

        The information from this event is not necessary for normal

        Namespace processing: the SAX XML reader will automatically

        replace prefixes for element and attribute names when the

        http://xml.org/sax/features/namespaces feature is true (the

        default).

        There are cases, however, when applications need to use

        prefixes in character data or in attribute values, where they

        cannot safely be expanded automatically; the

        start/endPrefixMapping event supplies the information to the

        application to expand prefixes in those contexts itself, if

        necessary.

        Note that start/endPrefixMapping events are not guaranteed to

        be properly nested relative to each-other: all

        startPrefixMapping events will occur before the corresponding

        startElement event, and all endPrefixMapping events will occur

        after the corresponding endElement event, but their order is

        not guaranteed."""

    def endPrefixMapping(self, prefix):

        """End the scope of a prefix-URI mapping.

        See startPrefixMapping for details. This event will always

        occur after the corresponding endElement event, but the order

        of endPrefixMapping events is not otherwise guaranteed."""

    def startElement(self, name, attrs):

        """Signals the start of an element in non-namespace mode.

        The name parameter contains the raw XML 1.0 name of the

        element type as a string and the attrs parameter holds an

        instance of the Attributes class containing the attributes of

        the element."""

    def endElement(self, name):

        """Signals the end of an element in non-namespace mode.

        The name parameter contains the name of the element type, just

        as with the startElement event."""

    def startElementNS(self, name, qname, attrs):

        """Signals the start of an element in namespace mode.

        The name parameter contains the name of the element type as a

        (uri, localname) tuple, the qname parameter the raw XML 1.0

        name used in the source document, and the attrs parameter

        holds an instance of the Attributes class containing the

        attributes of the element.

        The uri part of the name tuple is None for elements which have

        no namespace."""

    def endElementNS(self, name, qname):

        """Signals the end of an element in namespace mode.

        The name parameter contains the name of the element type, just

        as with the startElementNS event."""

    def characters(self, content):

        """Receive notification of character data.

        The Parser will call this method to report each chunk of

        character data. SAX parsers may return all contiguous

        character data in a single chunk, or they may split it into

        several chunks; however, all of the characters in any single

        event must come from the same external entity so that the

        Locator provides useful information."""

    def ignorableWhitespace(self, whitespace):

        """Receive notification of ignorable whitespace in element content.

        Validating Parsers must use this method to report each chunk

        of ignorable whitespace (see the W3C XML 1.0 recommendation,

        section 2.10): non-validating parsers may also use this method

        if they are capable of parsing and using content models.

        SAX parsers may return all contiguous whitespace in a single

        chunk, or they may split it into several chunks; however, all

        of the characters in any single event must come from the same

        external entity, so that the Locator provides useful

        information."""

    def processingInstruction(self, target, data):

        """Receive notification of a processing instruction.

        The Parser will invoke this method once for each processing

        instruction found: note that processing instructions may occur

        before or after the main document element.

        A SAX parser should never report an XML declaration (XML 1.0,

        section 2.8) or a text declaration (XML 1.0, section 4.3.1)

        using this method."""

    def skippedEntity(self, name):

        """Receive notification of a skipped entity.

        The Parser will invoke this method once for each entity

        skipped. Non-validating processors may skip entities if they

        have not seen the declarations (because, for example, the

        entity was declared in an external DTD subset). All processors

        may skip external entities, depending on the values of the

        http://xml.org/sax/features/external-general-entities and the

        http://xml.org/sax/features/external-parameter-entities

        properties."""

# ===== DTDHandler =====

class DTDHandler:

    """Handle DTD events.

    This interface specifies only those DTD events required for basic

    parsing (unparsed entities and attributes)."""

    def notationDecl(self, name, publicId, systemId):

        "Handle a notation declaration event."

    def unparsedEntityDecl(self, name, publicId, systemId, ndata):

        "Handle an unparsed entity declaration event."

# ===== ENTITYRESOLVER =====

class EntityResolver:

    """Basic interface for resolving entities. If you create an object

    implementing this interface, then register the object with your

    Parser, the parser will call the method in your object to

    resolve all external entities. Note that DefaultHandler implements

    this interface with the default behaviour."""

    def resolveEntity(self, publicId, systemId):

        """Resolve the system identifier of an entity and return either

        the system identifier to read from as a string, or an InputSource

        to read from."""

        return systemId

#============================================================================

#

# CORE FEATURES

#

#============================================================================

feature_namespaces = "http://xml.org/sax/features/namespaces"

# true: Perform Namespace processing (default).

# false: Optionally do not perform Namespace processing

#        (implies namespace-prefixes).

# access: (parsing) read-only; (not parsing) read/write

feature_namespace_prefixes = "http://xml.org/sax/features/namespace-prefixes"

# true: Report the original prefixed names and attributes used for Namespace

#       declarations.

# false: Do not report attributes used for Namespace declarations, and

#        optionally do not report original prefixed names (default).

# access: (parsing) read-only; (not parsing) read/write

feature_string_interning = "http://xml.org/sax/features/string-interning"

# true: All element names, prefixes, attribute names, Namespace URIs, and

#       local names are interned using the built-in intern function.

# false: Names are not necessarily interned, although they may be (default).

# access: (parsing) read-only; (not parsing) read/write

feature_validation = "http://xml.org/sax/features/validation"

# true: Report all validation errors (implies external-general-entities and

#       external-parameter-entities).

# false: Do not report validation errors.

# access: (parsing) read-only; (not parsing) read/write

feature_external_ges = "http://xml.org/sax/features/external-general-entities"

# true: Include all external general (text) entities.

# false: Do not include external general entities.

# access: (parsing) read-only; (not parsing) read/write

feature_external_pes = "http://xml.org/sax/features/external-parameter-entities"

# true: Include all external parameter entities, including the external

#       DTD subset.

# false: Do not include any external parameter entities, even the external

#        DTD subset.

# access: (parsing) read-only; (not parsing) read/write

all_features = [feature_namespaces,

                feature_namespace_prefixes,

                feature_string_interning,

                feature_validation,

                feature_external_ges,

                feature_external_pes]

#============================================================================

#

# CORE PROPERTIES

#

#============================================================================

property_lexical_handler = "http://xml.org/sax/properties/lexical-handler"

# data type: xml.sax.sax2lib.LexicalHandler

# description: An optional extension handler for lexical events like comments.

# access: read/write

property_declaration_handler = "http://xml.org/sax/properties/declaration-handler"

# data type: xml.sax.sax2lib.DeclHandler

# description: An optional extension handler for DTD-related events other

#              than notations and unparsed entities.

# access: read/write

property_dom_node = "http://xml.org/sax/properties/dom-node"

# data type: org.w3c.dom.Node

# description: When parsing, the current DOM node being visited if this is

#              a DOM iterator; when not parsing, the root DOM node for

#              iteration.

# access: (parsing) read-only; (not parsing) read/write

property_xml_string = "http://xml.org/sax/properties/xml-string"

# data type: String

# description: The literal string of characters that was the source for

#              the current event.

# access: read-only

property_encoding = "http://www.python.org/sax/properties/encoding"

# data type: String

# description: The name of the encoding to assume for input data.

# access: write: set the encoding, e.g. established by a higher-level

#                protocol. May change during parsing (e.g. after

#                processing a META tag)

#         read:  return the current encoding (possibly established through

#                auto-detection.

# initial value: UTF-8

#

property_interning_dict = "http://www.python.org/sax/properties/interning-dict"

# data type: Dictionary

# description: The dictionary used to intern common strings in the document

# access: write: Request that the parser uses a specific dictionary, to

#                allow interning across different documents

#         read:  return the current interning dictionary, or None

#

all_properties = [property_lexical_handler,

                  property_dom_node,

                  property_declaration_handler,

                  property_xml_string,

                  property_encoding,

                  property_interning_dict]