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# -*- coding: utf-8 -*-
"""
Options class: collect the possible options that govern the parsing possibilities. It also includes a reference and
handling of the extra Graph for warnings, informations, errors.
@summary: RDFa parser (distiller)
@requires: U{RDFLib<http://rdflib.net>}
@requires: U{html5lib<http://code.google.com/p/html5lib/>} for the HTML5 parsing; note possible dependecies on Python's version on the project's web site
@organization: U{World Wide Web Consortium<http://www.w3.org>}
@author: U{Ivan Herman<a href="http://www.w3.org/People/Ivan/">}
@license: This software is available for use under the
U{W3C® SOFTWARE NOTICE AND LICENSE<href="http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231">}
"""
import sys
from rdflib.graph import Graph
from rdflib.term import BNode, Literal, URIRef
from rdflib.namespace import Namespace
__all__ = ['CommentGraph', 'Options']
DIST_URI = "http://www.w3.org/2007/08/pyRdfa/distiller"
DIST_NS = DIST_URI + '#'
ns_errors = Namespace(DIST_NS)
distillerURI = URIRef(DIST_URI)
WARNING = 'warning'
ERROR = 'error'
INFO = 'info'
DEBUG = 'debug'
_message_properties = {
WARNING: ns_errors["warning"],
ERROR: ns_errors["error"],
INFO: ns_errors["information"],
DEBUG: ns_errors["debug"]
}
def _add_to_comment_graph(graph, msg, prop, uri):
"""
Add a distiller message to the graph.
@param graph: RDFLib Graph
@param msg: message of an exception
@type msg: RDFLIb Literal
@param prop: the property to be used
@type prop: string, must be one of 'warning', 'error', 'info', 'debug'
@param uri: the top URI used to invoke the distiller
@type uri: URIRef
"""
bnode = BNode()
graph.add((distillerURI, _message_properties[prop], bnode))
graph.add((bnode, ns_errors["onURI"], uri))
graph.add((bnode, ns_errors["message"], msg))
class CommentGraph(object):
"""Class to handle the 'comment graph', ie, the (RDF) Graph containing the warnings,
error messages, and informational messages.
"""
def __init__(self, warnings = False):
"""
@param warnings: whether a graph should effectively be set up, or whether this
should just be an empty shell for the various calls to work (without effect)
"""
if warnings:
self.graph = Graph()
else:
self.graph = None
self.accumulated_literals = []
self.baseURI = None
def _add_triple(self, msg, prop):
obj = Literal(msg)
if self.baseURI == None:
self.accumulated_literals.append((obj,prop))
elif self.graph != None:
_add_to_comment_graph(self.graph, obj, prop, self.baseURI)
def set_base_URI(self, URI):
"""Set the base URI for the comment triples.
Note that this method I{must} be called at some point to complete the triples. Without it the triples
added via L{add_warning<CommentGraph.add_warning>}, L{add_info<CommentGraph.add_info>}, etc, will not be added to the final graph.
@param URI: URIRef for the subject of the comments
"""
self.baseURI = URI
if self.graph != None:
for obj, prop in self.accumulated_literals:
_add_to_comment_graph(self.graph, obj, prop, self.baseURI)
self.accumulated_literals = []
def add_warning(self, txt):
"""Add a warning. A comment triplet is added to the separate "warning" graph.
@param txt: the warning text. It will be preceded by the string "==== pyRdfa Warning ==== "
"""
self._add_triple(txt, WARNING)
def add_info(self, txt):
"""Add an informational comment. A comment triplet is added to the separate "warning" graph.
@param txt: the information text. It will be preceded by the string "==== pyRdfa information ==== "
"""
self._add_triple(txt, INFO)
def add_error(self, txt):
"""Add an error comment. A comment triplet is added to the separate "warning" graph.
@param txt: the information text. It will be preceded by the string "==== pyRdfa information ==== "
"""
self._add_triple(txt, ERROR)
def _add_debug(self, txt):
self._add_triple(txt, DEBUG)
GENERIC_XML = 0
XHTML_RDFA = 1
HTML5_RDFA = 2
class Options(object):
"""Settable options. An instance of this class is stored in
the L{execution context<ExecutionContext>} of the parser.
@ivar space_preserve: whether plain literals should preserve spaces at output or not
@type space_preserve: Boolean
@ivar comment_graph: Graph for the storage of warnings
@type comment_graph: L{CommentGraph}
@ivar warnings: whether warnings should be generated or not
@type warnings: Boolean
@ivar transformers: extra transformers
@type transformers: list
@type host_language: the host language for the RDFa attributes. Default is XHTML_RDFA, but it can be GENERIC_XML and HTML5_RDFA
@ivar host_language: integer (logically: an enumeration)
@ivar lax: whether a 'lax' parsing of XHTML (ie, HTML5) is allowed. This means that the value of the host language might change run time
@type lax: Boolean
"""
def __init__(self, warnings=False, space_preserve=True, transformers=[], xhtml=True, lax=False):
"""
@param space_preserve: whether plain literals should preserve spaces at output or not
@type space_preserve: Boolean
@param warnings: whether warnings should be generated or not
@type warnings: Boolean
@param transformers: extra transformers
@type transformers: list
@param xhtml: initial value for the host language. If True, the value is set to XHTML_RDFA. Note that run-time the class variable might be set ot HTML5_RDFA, depending on the value of the lax flag and the result of parsing.
@type xhtml: Booelan
@param lax: whether a 'lax' parsing of XHTML (ie, HTML5) is allowed. This means that the value of the host language might change run time
@type lax: Boolean
"""
self.space_preserve = space_preserve
self.transformers = transformers
self.comment_graph = CommentGraph(warnings)
self.warnings = warnings
self.lax = lax
if xhtml:
self.host_language = XHTML_RDFA
else:
self.host_language = GENERIC_XML
def __str__(self):
retval = """Current options:
space_preserve : %s
warnings : %s
lax parsing : %s
host language : %s
"""
return retval % (self.space_preserve, self.warnings, self.lax, self.host_language)
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