1 | # -*- coding: utf-8 -*- |
---|
2 | # |
---|
3 | # Copyright (C) 2006-2009 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 | """Support for programmatically generating markup streams from Python code using |
---|
15 | a very simple syntax. The main entry point to this module is the `tag` object |
---|
16 | (which is actually an instance of the ``ElementFactory`` class). You should |
---|
17 | rarely (if ever) need to directly import and use any of the other classes in |
---|
18 | this module. |
---|
19 | |
---|
20 | Elements can be created using the `tag` object using attribute access. For |
---|
21 | example: |
---|
22 | |
---|
23 | >>> doc = tag.p('Some text and ', tag.a('a link', href='http://example.org/'), '.') |
---|
24 | >>> doc |
---|
25 | <Element "p"> |
---|
26 | |
---|
27 | This produces an `Element` instance which can be further modified to add child |
---|
28 | nodes and attributes. This is done by "calling" the element: positional |
---|
29 | arguments are added as child nodes (alternatively, the `Element.append` method |
---|
30 | can be used for that purpose), whereas keywords arguments are added as |
---|
31 | attributes: |
---|
32 | |
---|
33 | >>> doc(tag.br) |
---|
34 | <Element "p"> |
---|
35 | >>> print(doc) |
---|
36 | <p>Some text and <a href="http://example.org/">a link</a>.<br/></p> |
---|
37 | |
---|
38 | If an attribute name collides with a Python keyword, simply append an underscore |
---|
39 | to the name: |
---|
40 | |
---|
41 | >>> doc(class_='intro') |
---|
42 | <Element "p"> |
---|
43 | >>> print(doc) |
---|
44 | <p class="intro">Some text and <a href="http://example.org/">a link</a>.<br/></p> |
---|
45 | |
---|
46 | As shown above, an `Element` can easily be directly rendered to XML text by |
---|
47 | printing it or using the Python ``str()`` function. This is basically a |
---|
48 | shortcut for converting the `Element` to a stream and serializing that |
---|
49 | stream: |
---|
50 | |
---|
51 | >>> stream = doc.generate() |
---|
52 | >>> stream #doctest: +ELLIPSIS |
---|
53 | <genshi.core.Stream object at ...> |
---|
54 | >>> print(stream) |
---|
55 | <p class="intro">Some text and <a href="http://example.org/">a link</a>.<br/></p> |
---|
56 | |
---|
57 | |
---|
58 | The `tag` object also allows creating "fragments", which are basically lists |
---|
59 | of nodes (elements or text) that don't have a parent element. This can be useful |
---|
60 | for creating snippets of markup that are attached to a parent element later (for |
---|
61 | example in a template). Fragments are created by calling the `tag` object, which |
---|
62 | returns an object of type `Fragment`: |
---|
63 | |
---|
64 | >>> fragment = tag('Hello, ', tag.em('world'), '!') |
---|
65 | >>> fragment |
---|
66 | <Fragment> |
---|
67 | >>> print(fragment) |
---|
68 | Hello, <em>world</em>! |
---|
69 | """ |
---|
70 | |
---|
71 | from genshi.core import Attrs, Markup, Namespace, QName, Stream, \ |
---|
72 | START, END, TEXT |
---|
73 | |
---|
74 | __all__ = ['Fragment', 'Element', 'ElementFactory', 'tag'] |
---|
75 | __docformat__ = 'restructuredtext en' |
---|
76 | |
---|
77 | |
---|
78 | class Fragment(object): |
---|
79 | """Represents a markup fragment, which is basically just a list of element |
---|
80 | or text nodes. |
---|
81 | """ |
---|
82 | __slots__ = ['children'] |
---|
83 | |
---|
84 | def __init__(self): |
---|
85 | """Create a new fragment.""" |
---|
86 | self.children = [] |
---|
87 | |
---|
88 | def __add__(self, other): |
---|
89 | return Fragment()(self, other) |
---|
90 | |
---|
91 | def __call__(self, *args): |
---|
92 | """Append any positional arguments as child nodes. |
---|
93 | |
---|
94 | :see: `append` |
---|
95 | """ |
---|
96 | for arg in args: |
---|
97 | self.append(arg) |
---|
98 | return self |
---|
99 | |
---|
100 | def __iter__(self): |
---|
101 | return self._generate() |
---|
102 | |
---|
103 | def __repr__(self): |
---|
104 | return '<%s>' % type(self).__name__ |
---|
105 | |
---|
106 | def __str__(self): |
---|
107 | return str(self.generate()) |
---|
108 | |
---|
109 | def __unicode__(self): |
---|
110 | return unicode(self.generate()) |
---|
111 | |
---|
112 | def __html__(self): |
---|
113 | return Markup(self.generate()) |
---|
114 | |
---|
115 | def append(self, node): |
---|
116 | """Append an element or string as child node. |
---|
117 | |
---|
118 | :param node: the node to append; can be an `Element`, `Fragment`, or a |
---|
119 | `Stream`, or a Python string or number |
---|
120 | """ |
---|
121 | if isinstance(node, (Stream, Element, basestring, int, float, long)): |
---|
122 | # For objects of a known/primitive type, we avoid the check for |
---|
123 | # whether it is iterable for better performance |
---|
124 | self.children.append(node) |
---|
125 | elif isinstance(node, Fragment): |
---|
126 | self.children.extend(node.children) |
---|
127 | elif node is not None: |
---|
128 | try: |
---|
129 | for child in node: |
---|
130 | self.append(child) |
---|
131 | except TypeError: |
---|
132 | self.children.append(node) |
---|
133 | |
---|
134 | def _generate(self): |
---|
135 | for child in self.children: |
---|
136 | if isinstance(child, Fragment): |
---|
137 | for event in child._generate(): |
---|
138 | yield event |
---|
139 | elif isinstance(child, Stream): |
---|
140 | for event in child: |
---|
141 | yield event |
---|
142 | else: |
---|
143 | if not isinstance(child, basestring): |
---|
144 | child = unicode(child) |
---|
145 | yield TEXT, child, (None, -1, -1) |
---|
146 | |
---|
147 | def generate(self): |
---|
148 | """Return a markup event stream for the fragment. |
---|
149 | |
---|
150 | :rtype: `Stream` |
---|
151 | """ |
---|
152 | return Stream(self._generate()) |
---|
153 | |
---|
154 | |
---|
155 | def _kwargs_to_attrs(kwargs): |
---|
156 | attrs = [] |
---|
157 | names = set() |
---|
158 | for name, value in kwargs.items(): |
---|
159 | name = name.rstrip('_').replace('_', '-') |
---|
160 | if value is not None and name not in names: |
---|
161 | attrs.append((QName(name), unicode(value))) |
---|
162 | names.add(name) |
---|
163 | return Attrs(attrs) |
---|
164 | |
---|
165 | |
---|
166 | class Element(Fragment): |
---|
167 | """Simple XML output generator based on the builder pattern. |
---|
168 | |
---|
169 | Construct XML elements by passing the tag name to the constructor: |
---|
170 | |
---|
171 | >>> print(Element('strong')) |
---|
172 | <strong/> |
---|
173 | |
---|
174 | Attributes can be specified using keyword arguments. The values of the |
---|
175 | arguments will be converted to strings and any special XML characters |
---|
176 | escaped: |
---|
177 | |
---|
178 | >>> print(Element('textarea', rows=10, cols=60)) |
---|
179 | <textarea rows="10" cols="60"/> |
---|
180 | >>> print(Element('span', title='1 < 2')) |
---|
181 | <span title="1 < 2"/> |
---|
182 | >>> print(Element('span', title='"baz"')) |
---|
183 | <span title=""baz""/> |
---|
184 | |
---|
185 | The " character is escaped using a numerical entity. |
---|
186 | The order in which attributes are rendered is undefined. |
---|
187 | |
---|
188 | If an attribute value evaluates to `None`, that attribute is not included |
---|
189 | in the output: |
---|
190 | |
---|
191 | >>> print(Element('a', name=None)) |
---|
192 | <a/> |
---|
193 | |
---|
194 | Attribute names that conflict with Python keywords can be specified by |
---|
195 | appending an underscore: |
---|
196 | |
---|
197 | >>> print(Element('div', class_='warning')) |
---|
198 | <div class="warning"/> |
---|
199 | |
---|
200 | Nested elements can be added to an element using item access notation. |
---|
201 | The call notation can also be used for this and for adding attributes |
---|
202 | using keyword arguments, as one would do in the constructor. |
---|
203 | |
---|
204 | >>> print(Element('ul')(Element('li'), Element('li'))) |
---|
205 | <ul><li/><li/></ul> |
---|
206 | >>> print(Element('a')('Label')) |
---|
207 | <a>Label</a> |
---|
208 | >>> print(Element('a')('Label', href="target")) |
---|
209 | <a href="target">Label</a> |
---|
210 | |
---|
211 | Text nodes can be nested in an element by adding strings instead of |
---|
212 | elements. Any special characters in the strings are escaped automatically: |
---|
213 | |
---|
214 | >>> print(Element('em')('Hello world')) |
---|
215 | <em>Hello world</em> |
---|
216 | >>> print(Element('em')(42)) |
---|
217 | <em>42</em> |
---|
218 | >>> print(Element('em')('1 < 2')) |
---|
219 | <em>1 < 2</em> |
---|
220 | |
---|
221 | This technique also allows mixed content: |
---|
222 | |
---|
223 | >>> print(Element('p')('Hello ', Element('b')('world'))) |
---|
224 | <p>Hello <b>world</b></p> |
---|
225 | |
---|
226 | Quotes are not escaped inside text nodes: |
---|
227 | >>> print(Element('p')('"Hello"')) |
---|
228 | <p>"Hello"</p> |
---|
229 | |
---|
230 | Elements can also be combined with other elements or strings using the |
---|
231 | addition operator, which results in a `Fragment` object that contains the |
---|
232 | operands: |
---|
233 | |
---|
234 | >>> print(Element('br') + 'some text' + Element('br')) |
---|
235 | <br/>some text<br/> |
---|
236 | |
---|
237 | Elements with a namespace can be generated using the `Namespace` and/or |
---|
238 | `QName` classes: |
---|
239 | |
---|
240 | >>> from genshi.core import Namespace |
---|
241 | >>> xhtml = Namespace('http://www.w3.org/1999/xhtml') |
---|
242 | >>> print(Element(xhtml.html, lang='en')) |
---|
243 | <html xmlns="http://www.w3.org/1999/xhtml" lang="en"/> |
---|
244 | """ |
---|
245 | __slots__ = ['tag', 'attrib'] |
---|
246 | |
---|
247 | def __init__(self, tag_, **attrib): |
---|
248 | Fragment.__init__(self) |
---|
249 | self.tag = QName(tag_) |
---|
250 | self.attrib = _kwargs_to_attrs(attrib) |
---|
251 | |
---|
252 | def __call__(self, *args, **kwargs): |
---|
253 | """Append any positional arguments as child nodes, and keyword arguments |
---|
254 | as attributes. |
---|
255 | |
---|
256 | :return: the element itself so that calls can be chained |
---|
257 | :rtype: `Element` |
---|
258 | :see: `Fragment.append` |
---|
259 | """ |
---|
260 | self.attrib |= _kwargs_to_attrs(kwargs) |
---|
261 | Fragment.__call__(self, *args) |
---|
262 | return self |
---|
263 | |
---|
264 | def __repr__(self): |
---|
265 | return '<%s "%s">' % (type(self).__name__, self.tag) |
---|
266 | |
---|
267 | def _generate(self): |
---|
268 | yield START, (self.tag, self.attrib), (None, -1, -1) |
---|
269 | for kind, data, pos in Fragment._generate(self): |
---|
270 | yield kind, data, pos |
---|
271 | yield END, self.tag, (None, -1, -1) |
---|
272 | |
---|
273 | def generate(self): |
---|
274 | """Return a markup event stream for the fragment. |
---|
275 | |
---|
276 | :rtype: `Stream` |
---|
277 | """ |
---|
278 | return Stream(self._generate()) |
---|
279 | |
---|
280 | |
---|
281 | class ElementFactory(object): |
---|
282 | """Factory for `Element` objects. |
---|
283 | |
---|
284 | A new element is created simply by accessing a correspondingly named |
---|
285 | attribute of the factory object: |
---|
286 | |
---|
287 | >>> factory = ElementFactory() |
---|
288 | >>> print(factory.foo) |
---|
289 | <foo/> |
---|
290 | >>> print(factory.foo(id=2)) |
---|
291 | <foo id="2"/> |
---|
292 | |
---|
293 | Markup fragments (lists of nodes without a parent element) can be created |
---|
294 | by calling the factory: |
---|
295 | |
---|
296 | >>> print(factory('Hello, ', factory.em('world'), '!')) |
---|
297 | Hello, <em>world</em>! |
---|
298 | |
---|
299 | A factory can also be bound to a specific namespace: |
---|
300 | |
---|
301 | >>> factory = ElementFactory('http://www.w3.org/1999/xhtml') |
---|
302 | >>> print(factory.html(lang="en")) |
---|
303 | <html xmlns="http://www.w3.org/1999/xhtml" lang="en"/> |
---|
304 | |
---|
305 | The namespace for a specific element can be altered on an existing factory |
---|
306 | by specifying the new namespace using item access: |
---|
307 | |
---|
308 | >>> factory = ElementFactory() |
---|
309 | >>> print(factory.html(factory['http://www.w3.org/2000/svg'].g(id=3))) |
---|
310 | <html><g xmlns="http://www.w3.org/2000/svg" id="3"/></html> |
---|
311 | |
---|
312 | Usually, the `ElementFactory` class is not be used directly. Rather, the |
---|
313 | `tag` instance should be used to create elements. |
---|
314 | """ |
---|
315 | |
---|
316 | def __init__(self, namespace=None): |
---|
317 | """Create the factory, optionally bound to the given namespace. |
---|
318 | |
---|
319 | :param namespace: the namespace URI for any created elements, or `None` |
---|
320 | for no namespace |
---|
321 | """ |
---|
322 | if namespace and not isinstance(namespace, Namespace): |
---|
323 | namespace = Namespace(namespace) |
---|
324 | self.namespace = namespace |
---|
325 | |
---|
326 | def __call__(self, *args): |
---|
327 | """Create a fragment that has the given positional arguments as child |
---|
328 | nodes. |
---|
329 | |
---|
330 | :return: the created `Fragment` |
---|
331 | :rtype: `Fragment` |
---|
332 | """ |
---|
333 | return Fragment()(*args) |
---|
334 | |
---|
335 | def __getitem__(self, namespace): |
---|
336 | """Return a new factory that is bound to the specified namespace. |
---|
337 | |
---|
338 | :param namespace: the namespace URI or `Namespace` object |
---|
339 | :return: an `ElementFactory` that produces elements bound to the given |
---|
340 | namespace |
---|
341 | :rtype: `ElementFactory` |
---|
342 | """ |
---|
343 | return ElementFactory(namespace) |
---|
344 | |
---|
345 | def __getattr__(self, name): |
---|
346 | """Create an `Element` with the given name. |
---|
347 | |
---|
348 | :param name: the tag name of the element to create |
---|
349 | :return: an `Element` with the specified name |
---|
350 | :rtype: `Element` |
---|
351 | """ |
---|
352 | return Element(self.namespace and self.namespace[name] or name) |
---|
353 | |
---|
354 | |
---|
355 | tag = ElementFactory() |
---|
356 | """Global `ElementFactory` bound to the default namespace. |
---|
357 | |
---|
358 | :type: `ElementFactory` |
---|
359 | """ |
---|