1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
"""
From a Python file, expecting an RDF/XML pretty printed output::
import rdflib.graph as g
graph = g.Graph()
graph.parse('filename.html', format='rdfa')
print graph.serialize(format='pretty-xml')
For details on RDFa, the reader should consult the `RDFa syntax document`__.
This is an adapted version of pyRdfa (`W3C RDFa Distiller page`__) by Ivan Herman
.. __: http://www.w3.org/TR/rdfa-syntax
.. __: http://www.w3.org/2007/08/pyRdfa/
"""
import sys
import urllib
import xml.dom.minidom
from rdflib.term import URIRef
from rdflib.parser import Parser
from rdflib.plugins.parsers.rdfa.state import ExecutionContext
from rdflib.plugins.parsers.rdfa.parse import parse_one_node
from rdflib.plugins.parsers.rdfa.options import (Options, _add_to_comment_graph,
DIST_NS, ERROR, GENERIC_XML, XHTML_RDFA, HTML5_RDFA)
from rdflib.plugins.parsers.rdfa.transform.headabout import head_about_transform
__all__ = ['RDFaParser']
# These are part of the RDFa spec.
BUILT_IN_TRANSFORMERS = [
head_about_transform
]
# Exception handling. Essentially, all the different exceptions are re-packaged
# into separate exception class, to allow for an easier management on the user
# level
class RDFaError(Exception) :
"""Just a wrapper around the local exceptions. It does not add any new
functionality to the Exception class."""
pass
# For some doctype and element name combinations an automatic switch to an
# input mode is done
_HOST_LANG = {
("http://www.w3.org/1999/xhtml", "html"): XHTML_RDFA,
("http://www.w3.org/2000/svg", "svg"): GENERIC_XML
}
class RDFaParser(Parser):
def parse(self, source, sink,
warnings=False, space_preserve=True,
transformers=None, xhtml=True, lax=True, html5=False, encoding=None):
if transformers is None:
transformers = []
options = Options(warnings, space_preserve, transformers, xhtml, lax)
baseURI = source.getPublicId()
stream = source.getByteStream()
if html5:
dom = _process_html5_source(stream, options, encoding)
else:
dom = _try_process_source(stream, options, encoding)
_process_DOM(dom, baseURI, sink, options)
def _process_DOM(dom, base, graph, options=None):
"""
Core processing. The transformers ("pre-processing") is done on the DOM
tree, the state is initialized, and the "real" RDFa parsing is done.
The result is put into the provided Graph.
The real work is done in the parser function ``parse_one_node()``.
Params:
dom -- XML DOM Tree node (for the top level)
base -- URI for the default "base" value (usually the URI of the file to be processed)
Options:
obj -- `Options` for the distiller
raise RDFaError -- when called via CGI, this encapsulates the possible
exceptions raised by the RDFLib serializer or the processing itself
"""
html = dom.documentElement
# Perform the built-in and external transformations on the HTML tree. This is,
# in simulated form, the hGRDDL approach of Ben Adida.
for trans in options.transformers + BUILT_IN_TRANSFORMERS:
trans(html, options)
# Collect the initial state. This takes care of things
# like base, top level namespace settings, etc.
# Ensure the proper initialization.
state = ExecutionContext(html, graph, base=base, options=options)
# The top level subject starts with the current document; this
# is used by the recursion
subject = URIRef(state.base)
# Parse the whole thing recursively and fill the graph.
parse_one_node(html, graph, subject, state, [])
if options.comment_graph.graph != None:
# Add the content of the comment graph to the output.
graph.bind("dist", DIST_NS)
for t in options.comment_graph.graph:
graph.add(t)
def _try_process_source(stream, options, encoding):
"""
Tries to parse input as xhtml, xml (e.g. svg) or html(5), modifying options
while figuring out input..
Returns a DOM tree.
"""
parse = xml.dom.minidom.parse
try:
dom = parse(stream)
# Try to second-guess the input type
# This is _not_ really kosher, but the minidom is not really namespace aware...
# In practice the goal is to have the system recognize svg content automatically
# First see if there is a default namespace defined for the document:
top = dom.documentElement
if top.hasAttribute("xmlns"):
key = (top.getAttribute("xmlns"), top.nodeName)
if key in _HOST_LANG:
options.host_language = _HOST_LANG[key]
return dom
except:
# XML Parsing error in the input
type, value, traceback = sys.exc_info()
if options.host_language == GENERIC_XML or options.lax == False:
raise RDFaError('Parsing error in input file: "%s"' % value)
# XML Parsing error in the input
msg = "XHTML Parsing error in input file: %s. Falling back on the HTML5 parser" % value
if options != None and options.warnings:
options.comment_graph.add_warning(msg)
# in Ivan's original code he reopened the stream if it was from urllib
if isinstance(stream, urllib.addinfourl):
stream = urllib.urlopen(stream.url)
return _process_html5_source(stream, options, encoding)
def _process_html5_source(stream, options, encoding):
# Now try to see if and HTML5 parser is an alternative...
try:
from html5lib import HTMLParser, treebuilders
except ImportError:
# no alternative to the XHTML error, because HTML5 parser not available...
msg2 = 'XHTML Parsing error in input file: %s. Though parsing is lax, HTML5 parser not available. Try installing html5lib <http://code.google.com/p/html5lib>'
raise RDFaError(msg2)
parser = HTMLParser(tree=treebuilders.getTreeBuilder("dom"))
parse = parser.parse
try:
dom = parse(stream, encoding)
# The host language has changed
options.host_language = HTML5_RDFA
except:
# Well, even the HTML5 parser could not do anything with this...
(type, value, traceback) = sys.exc_info()
msg2 = 'Parsing error in input file as HTML5: "%s"' % value
raise RDFaError, msg2
return dom
|
