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markup.py

Last change on this file was 705, checked in by cmlenz, 16 years ago
Ported [704] to 0.4.x branch.
Property svn:eol-style set to `native`
File size: 14.4 KB

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1	# -- coding: utf-8 --
2	#
3	# Copyright (C) 2006-2007 Edgewall Software
4	# All rights reserved.
5	#
6	# This software is licensed as described in the file COPYING, which
7	# you should have received as part of this distribution. The terms
8	# are also available at http://genshi.edgewall.org/wiki/License.
9	#
10	# This software consists of voluntary contributions made by many
11	# individuals. For the exact contribution history, see the revision
12	# history and logs, available at http://genshi.edgewall.org/log/.
13
14	"""Markup templating engine."""
15
16	from itertools import chain
17	import sys
18	from textwrap import dedent
19
20	from genshi.core import Attrs, Namespace, Stream, StreamEventKind
21	from genshi.core import START, END, START_NS, END_NS, TEXT, PI, COMMENT
22	from genshi.input import XMLParser
23	from genshi.template.base import BadDirectiveError, Template, \
24	TemplateSyntaxError, _apply_directives, SUB
25	from genshi.template.eval import Suite
26	from genshi.template.interpolation import interpolate
27	from genshi.template.loader import TemplateNotFound
28	from genshi.template.directives import *
29
30	if sys.version_info < (2, 4):
31	_ctxt2dict = lambda ctxt: ctxt.frames[0]
32	else:
33	_ctxt2dict = lambda ctxt: ctxt
34
35	__all__ = ['MarkupTemplate']
36	__docformat__ = 'restructuredtext en'
37
38
39	class MarkupTemplate(Template):
40	"""Implementation of the template language for XML-based templates.
41
42	>>> tmpl = MarkupTemplate('''<ul xmlns:py="http://genshi.edgewall.org/">
43	... <li py:for="item in items">${item}</li>
44	... </ul>''')
45	>>> print tmpl.generate(items=[1, 2, 3])
46	<ul>
47	<li>1</li><li>2</li><li>3</li>
48	</ul>
49	"""
50	EXEC = StreamEventKind('EXEC')
51	"""Stream event kind representing a Python code suite to execute."""
52
53	INCLUDE = StreamEventKind('INCLUDE')
54	"""Stream event kind representing the inclusion of another template."""
55
56	DIRECTIVE_NAMESPACE = Namespace('http://genshi.edgewall.org/')
57	XINCLUDE_NAMESPACE = Namespace('http://www.w3.org/2001/XInclude')
58
59	directives = [('def', DefDirective),
60	('match', MatchDirective),
61	('when', WhenDirective),
62	('otherwise', OtherwiseDirective),
63	('for', ForDirective),
64	('if', IfDirective),
65	('choose', ChooseDirective),
66	('with', WithDirective),
67	('replace', ReplaceDirective),
68	('content', ContentDirective),
69	('attrs', AttrsDirective),
70	('strip', StripDirective)]
71
72	def __init__(self, source, basedir=None, filename=None, loader=None,
73	encoding=None, lookup='lenient'):
74	Template.__init__(self, source, basedir=basedir, filename=filename,
75	loader=loader, encoding=encoding, lookup=lookup)
76
77	self.filters += [self._exec, self._match]
78	if loader:
79	self.filters.append(self._include)
80
81	def _parse(self, source, encoding):
82	streams = [[]] # stacked lists of events of the "compiled" template
83	dirmap = {} # temporary mapping of directives to elements
84	ns_prefix = {}
85	depth = 0
86	fallbacks = []
87	includes = []
88
89	if not isinstance(source, Stream):
90	source = XMLParser(source, filename=self.filename,
91	encoding=encoding)
92
93	for kind, data, pos in source:
94	stream = streams[-1]
95
96	if kind is START_NS:
97	# Strip out the namespace declaration for template directives
98	prefix, uri = data
99	ns_prefix[prefix] = uri
100	if uri not in (self.DIRECTIVE_NAMESPACE,
101	self.XINCLUDE_NAMESPACE):
102	stream.append((kind, data, pos))
103
104	elif kind is END_NS:
105	uri = ns_prefix.pop(data, None)
106	if uri and uri not in (self.DIRECTIVE_NAMESPACE,
107	self.XINCLUDE_NAMESPACE):
108	stream.append((kind, data, pos))
109
110	elif kind is START:
111	# Record any directive attributes in start tags
112	tag, attrs = data
113	directives = []
114	strip = False
115
116	if tag in self.DIRECTIVE_NAMESPACE:
117	cls = self._dir_by_name.get(tag.localname)
118	if cls is None:
119	raise BadDirectiveError(tag.localname, self.filepath,
120	pos[1])
121	value = attrs.get(getattr(cls, 'ATTRIBUTE', None), '')
122	directives.append((cls, value, ns_prefix.copy(), pos))
123	strip = True
124
125	new_attrs = []
126	for name, value in attrs:
127	if name in self.DIRECTIVE_NAMESPACE:
128	cls = self._dir_by_name.get(name.localname)
129	if cls is None:
130	raise BadDirectiveError(name.localname,
131	self.filepath, pos[1])
132	directives.append((cls, value, ns_prefix.copy(), pos))
133	else:
134	if value:
135	value = list(interpolate(value, self.basedir,
136	pos[0], pos[1], pos[2],
137	lookup=self.lookup))
138	if len(value) == 1 and value[0][0] is TEXT:
139	value = value[0][1]
140	else:
141	value = [(TEXT, u'', pos)]
142	new_attrs.append((name, value))
143	new_attrs = Attrs(new_attrs)
144
145	if directives:
146	index = self._dir_order.index
147	directives.sort(lambda a, b: cmp(index(a[0]), index(b[0])))
148	dirmap[(depth, tag)] = (directives, len(stream), strip)
149
150	if tag in self.XINCLUDE_NAMESPACE:
151	if tag.localname == 'include':
152	include_href = new_attrs.get('href')
153	if not include_href:
154	raise TemplateSyntaxError('Include misses required '
155	'attribute "href"',
156	self.filepath, *pos[1:])
157	includes.append(include_href)
158	streams.append([])
159	elif tag.localname == 'fallback':
160	streams.append([])
161	fallbacks.append(streams[-1])
162
163	else:
164	stream.append((kind, (tag, new_attrs), pos))
165
166	depth += 1
167
168	elif kind is END:
169	depth -= 1
170
171	if fallbacks and data == self.XINCLUDE_NAMESPACE['fallback']:
172	assert streams.pop() is fallbacks[-1]
173	elif data == self.XINCLUDE_NAMESPACE['include']:
174	fallback = None
175	if len(fallbacks) == len(includes):
176	fallback = fallbacks.pop()
177	streams.pop() # discard anything between the include tags
178	# and the fallback element
179	stream = streams[-1]
180	stream.append((INCLUDE, (includes.pop(), fallback), pos))
181	else:
182	stream.append((kind, data, pos))
183
184	# If there have have directive attributes with the corresponding
185	# start tag, move the events inbetween into a "subprogram"
186	if (depth, data) in dirmap:
187	directives, start_offset, strip = dirmap.pop((depth, data))
188	substream = stream[start_offset:]
189	if strip:
190	substream = substream[1:-1]
191	stream[start_offset:] = [(SUB, (directives, substream),
192	pos)]
193
194	elif kind is PI and data[0] == 'python':
195	try:
196	# As Expat doesn't report whitespace between the PI target
197	# and the data, we have to jump through some hoops here to
198	# get correctly indented Python code
199	# Unfortunately, we'll still probably not get the line
200	# number quite right
201	lines = [line.expandtabs() for line in data[1].splitlines()]
202	first = lines[0]
203	rest = dedent('\n'.join(lines[1:])).rstrip()
204	if first.rstrip().endswith(':') and not rest[0].isspace():
205	rest = '\n'.join([' ' + line for line
206	in rest.splitlines()])
207	source = '\n'.join([first, rest])
208	suite = Suite(source, self.filepath, pos[1],
209	lookup=self.lookup)
210	except SyntaxError, err:
211	raise TemplateSyntaxError(err, self.filepath,
212	pos[1] + (err.lineno or 1) - 1,
213	pos[2] + (err.offset or 0))
214	stream.append((EXEC, suite, pos))
215
216	elif kind is TEXT:
217	for kind, data, pos in interpolate(data, self.basedir, pos[0],
218	pos[1], pos[2],
219	lookup=self.lookup):
220	stream.append((kind, data, pos))
221
222	elif kind is COMMENT:
223	if not data.lstrip().startswith('!'):
224	stream.append((kind, data, pos))
225
226	else:
227	stream.append((kind, data, pos))
228
229	assert len(streams) == 1
230	return streams[0]
231
232	def _prepare(self, stream):
233	for kind, data, pos in Template._prepare(self, stream):
234	if kind is INCLUDE and data[1]:
235	data = data[0], list(self._prepare(data[1]))
236	yield kind, data, pos
237
238	def _exec(self, stream, ctxt):
239	"""Internal stream filter that executes code in ``<?python ?>``
240	processing instructions.
241	"""
242	for event in stream:
243	if event[0] is EXEC:
244	event[1].execute(_ctxt2dict(ctxt))
245	else:
246	yield event
247
248	def _include(self, stream, ctxt):
249	"""Internal stream filter that performs inclusion of external
250	template files.
251	"""
252	for event in stream:
253	if event[0] is INCLUDE:
254	href, fallback = event[1]
255	if not isinstance(href, basestring):
256	parts = []
257	for subkind, subdata, subpos in self._eval(href, ctxt):
258	if subkind is TEXT:
259	parts.append(subdata)
260	href = u''.join([x for x in parts if x is not None])
261	try:
262	tmpl = self.loader.load(href, relative_to=event[2][0])
263	for event in tmpl.generate(ctxt):
264	yield event
265	except TemplateNotFound:
266	if fallback is None:
267	raise
268	for filter_ in self.filters:
269	fallback = filter_(iter(fallback), ctxt)
270	for event in fallback:
271	yield event
272	else:
273	yield event
274
275	def _match(self, stream, ctxt, match_templates=None):
276	"""Internal stream filter that applies any defined match templates
277	to the stream.
278	"""
279	if match_templates is None:
280	match_templates = ctxt._match_templates
281
282	tail = []
283	def _strip(stream):
284	depth = 1
285	while 1:
286	event = stream.next()
287	if event[0] is START:
288	depth += 1
289	elif event[0] is END:
290	depth -= 1
291	if depth > 0:
292	yield event
293	else:
294	tail[:] = [event]
295	break
296
297	for event in stream:
298
299	# We (currently) only care about start and end events for matching
300	# We might care about namespace events in the future, though
301	if not match_templates or (event[0] is not START and
302	event[0] is not END):
303	yield event
304	continue
305
306	for idx, (test, path, template, namespaces, directives) in \
307	enumerate(match_templates):
308
309	if test(event, namespaces, ctxt) is True:
310
311	# Let the remaining match templates know about the event so
312	# they get a chance to update their internal state
313	for test in [mt[0] for mt in match_templates[idx + 1:]]:
314	test(event, namespaces, ctxt, updateonly=True)
315
316	# Consume and store all events until an end event
317	# corresponding to this start event is encountered
318	content = chain([event],
319	self._match(_strip(stream), ctxt,
320	[match_templates[idx]]),
321	tail)
322	content = list(self._include(content, ctxt))
323
324	for test in [mt[0] for mt in match_templates]:
325	test(tail[0], namespaces, ctxt, updateonly=True)
326
327	# Make the select() function available in the body of the
328	# match template
329	def select(path):
330	return Stream(content).select(path, namespaces, ctxt)
331	ctxt.push(dict(select=select))
332
333	# Recursively process the output
334	template = _apply_directives(template, ctxt, directives)
335	for event in self._match(self._eval(self._flatten(template,
336	ctxt),
337	ctxt), ctxt,
338	match_templates[:idx] +
339	match_templates[idx + 1:]):
340	yield event
341
342	ctxt.pop()
343	break
344
345	else: # no matches
346	yield event
347
348
349	EXEC = MarkupTemplate.EXEC
350	INCLUDE = MarkupTemplate.INCLUDE

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