Mercurial > genshi > genshi-test
annotate markup/builder.py @ 119:61b133ed95b2
Allow creating fragments from the `tag` object in `markup.builder`.
| author | cmlenz |
|---|---|
| date | Wed, 02 Aug 2006 08:03:31 +0000 |
| parents | bc73d3ab823f |
| children | b9a0031d4bbb |
| rev | line source |
|---|---|
| 1 | 1 # -*- coding: utf-8 -*- |
| 2 # | |
|
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3 # Copyright (C) 2006 Edgewall Software |
| 1 | 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 | |
|
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8 # are also available at http://markup.edgewall.org/wiki/License. |
| 1 | 9 # |
| 10 # This software consists of voluntary contributions made by many | |
| 11 # individuals. For the exact contribution history, see the revision | |
|
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12 # history and logs, available at http://markup.edgewall.org/log/. |
| 1 | 13 |
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14 from markup.core import Attributes, Namespace, QName, Stream, escape |
| 1 | 15 |
| 16 __all__ = ['Fragment', 'Element', 'tag'] | |
| 17 | |
| 18 | |
| 19 class Fragment(object): | |
| 28 | 20 """Represents a markup fragment, which is basically just a list of element |
| 21 or text nodes. | |
| 22 """ | |
| 1 | 23 __slots__ = ['children'] |
| 24 | |
| 25 def __init__(self): | |
| 26 self.children = [] | |
| 27 | |
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28 def __add__(self, other): |
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29 return Fragment()(self, other) |
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30 |
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31 def __call__(self, *args): |
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32 for arg in args: |
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33 self.append(arg) |
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34 return self |
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35 |
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36 def __iter__(self): |
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37 return self._generate() |
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38 |
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39 def __repr__(self): |
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40 return '<%s>' % self.__class__.__name__ |
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41 |
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42 def __str__(self): |
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43 return str(self.generate()) |
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44 |
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45 def __unicode__(self): |
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46 return unicode(self.generate()) |
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47 |
| 1 | 48 def append(self, node): |
| 49 """Append an element or string as child node.""" | |
| 50 if isinstance(node, (Element, basestring, int, float, long)): | |
| 51 # For objects of a known/primitive type, we avoid the check for | |
| 52 # whether it is iterable for better performance | |
| 53 self.children.append(node) | |
| 54 elif isinstance(node, Fragment): | |
| 55 self.children += node.children | |
| 56 elif node is not None: | |
| 57 try: | |
| 58 children = iter(node) | |
| 59 except TypeError: | |
| 60 self.children.append(node) | |
| 61 else: | |
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62 for child in children: |
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63 self.append(child) |
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64 |
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65 def _generate(self): |
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66 for child in self.children: |
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67 if isinstance(child, Fragment): |
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68 for event in child._generate(): |
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69 yield event |
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70 else: |
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71 if not isinstance(child, basestring): |
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72 child = unicode(child) |
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73 yield Stream.TEXT, child, (None, -1, -1) |
| 1 | 74 |
| 75 def generate(self): | |
| 28 | 76 """Return a markup event stream for the fragment.""" |
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77 return Stream(self._generate()) |
| 1 | 78 |
| 79 | |
| 80 class Element(Fragment): | |
| 81 """Simple XML output generator based on the builder pattern. | |
| 82 | |
| 83 Construct XML elements by passing the tag name to the constructor: | |
| 84 | |
| 85 >>> print Element('strong') | |
| 86 <strong/> | |
| 87 | |
| 88 Attributes can be specified using keyword arguments. The values of the | |
| 89 arguments will be converted to strings and any special XML characters | |
| 90 escaped: | |
| 91 | |
| 92 >>> print Element('textarea', rows=10, cols=60) | |
| 93 <textarea rows="10" cols="60"/> | |
| 94 >>> print Element('span', title='1 < 2') | |
| 95 <span title="1 < 2"/> | |
| 96 >>> print Element('span', title='"baz"') | |
| 97 <span title=""baz""/> | |
| 98 | |
| 99 The " character is escaped using a numerical entity. | |
| 100 The order in which attributes are rendered is undefined. | |
| 101 | |
| 102 If an attribute value evaluates to `None`, that attribute is not included | |
| 103 in the output: | |
| 104 | |
| 105 >>> print Element('a', name=None) | |
| 106 <a/> | |
| 107 | |
| 108 Attribute names that conflict with Python keywords can be specified by | |
| 109 appending an underscore: | |
| 110 | |
| 111 >>> print Element('div', class_='warning') | |
| 112 <div class="warning"/> | |
| 113 | |
| 114 Nested elements can be added to an element using item access notation. | |
| 115 The call notation can also be used for this and for adding attributes | |
| 116 using keyword arguments, as one would do in the constructor. | |
| 117 | |
| 118 >>> print Element('ul')(Element('li'), Element('li')) | |
| 119 <ul><li/><li/></ul> | |
| 120 >>> print Element('a')('Label') | |
| 121 <a>Label</a> | |
| 122 >>> print Element('a')('Label', href="target") | |
| 123 <a href="target">Label</a> | |
| 124 | |
| 125 Text nodes can be nested in an element by adding strings instead of | |
| 126 elements. Any special characters in the strings are escaped automatically: | |
| 127 | |
| 128 >>> print Element('em')('Hello world') | |
| 129 <em>Hello world</em> | |
| 130 >>> print Element('em')(42) | |
| 131 <em>42</em> | |
| 132 >>> print Element('em')('1 < 2') | |
| 133 <em>1 < 2</em> | |
| 134 | |
| 135 This technique also allows mixed content: | |
| 136 | |
| 137 >>> print Element('p')('Hello ', Element('b')('world')) | |
| 138 <p>Hello <b>world</b></p> | |
| 139 | |
| 34 | 140 Quotes are not escaped inside text nodes: |
| 141 >>> print Element('p')('"Hello"') | |
| 142 <p>"Hello"</p> | |
| 143 | |
| 1 | 144 Elements can also be combined with other elements or strings using the |
| 145 addition operator, which results in a `Fragment` object that contains the | |
| 146 operands: | |
| 147 | |
| 148 >>> print Element('br') + 'some text' + Element('br') | |
| 149 <br/>some text<br/> | |
| 150 | |
| 151 Elements with a namespace can be generated using the `Namespace` and/or | |
| 152 `QName` classes: | |
| 153 | |
| 154 >>> from markup.core import Namespace | |
| 155 >>> xhtml = Namespace('http://www.w3.org/1999/xhtml') | |
| 156 >>> print Element(xhtml.html, lang='en') | |
| 157 <html lang="en" xmlns="http://www.w3.org/1999/xhtml"/> | |
| 158 """ | |
| 159 __slots__ = ['tag', 'attrib'] | |
| 160 | |
| 161 def __init__(self, tag_, **attrib): | |
| 162 Fragment.__init__(self) | |
| 163 self.tag = QName(tag_) | |
| 164 self.attrib = Attributes() | |
| 165 self(**attrib) | |
| 166 | |
| 167 def __call__(self, *args, **kwargs): | |
| 168 for attr, value in kwargs.items(): | |
| 169 if value is None: | |
| 170 continue | |
| 171 attr = attr.rstrip('_').replace('_', '-') | |
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172 self.attrib.set(attr, escape(value)) |
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173 Fragment.__call__(self, *args) |
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174 return self |
| 1 | 175 |
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176 def __repr__(self): |
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177 return '<%s "%s">' % (self.__class__.__name__, self.tag) |
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178 |
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179 def _generate(self): |
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180 attrib = Attributes() |
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181 for attr, value in self.attrib: |
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182 if not isinstance(value, basestring): |
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183 value = unicode(value) |
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184 attrib.append((attr, value)) |
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185 yield Stream.START, (self.tag, attrib), (None, -1, -1) |
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186 for kind, data, pos in Fragment._generate(self): |
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187 yield kind, data, pos |
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188 yield Stream.END, self.tag, (None, -1, -1) |
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189 |
| 1 | 190 def generate(self): |
| 28 | 191 """Return a markup event stream for the fragment.""" |
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192 return Stream(self._generate()) |
| 1 | 193 |
| 194 | |
| 195 class ElementFactory(object): | |
| 28 | 196 """Factory for `Element` objects. |
| 197 | |
| 198 A new element is created simply by accessing a correspondingly named | |
| 199 attribute of the factory object: | |
| 200 | |
| 201 >>> factory = ElementFactory() | |
| 202 >>> print factory.foo | |
| 203 <foo/> | |
| 204 >>> print factory.foo(id=2) | |
| 205 <foo id="2"/> | |
| 206 | |
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207 Markup fragments (lists of nodes without a parent element) can be created |
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208 by calling the factory: |
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209 |
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210 >>> print factory('Hello, ', factory.em('world'), '!') |
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211 Hello, <em>world</em>! |
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212 |
| 28 | 213 A factory can also be bound to a specific namespace: |
| 214 | |
| 215 >>> factory = ElementFactory('http://www.w3.org/1999/xhtml') | |
| 216 >>> print factory.html(lang="en") | |
| 217 <html lang="en" xmlns="http://www.w3.org/1999/xhtml"/> | |
| 218 | |
| 219 The namespace for a specific element can be altered on an existing factory | |
| 220 by specifying the new namespace using item access: | |
| 221 | |
| 222 >>> factory = ElementFactory() | |
| 223 >>> print factory.html(factory['http://www.w3.org/2000/svg'].g(id=3)) | |
| 224 <html><g id="3" xmlns="http://www.w3.org/2000/svg"/></html> | |
| 225 | |
| 226 Usually, the `ElementFactory` class is not be used directly. Rather, the | |
| 227 `tag` instance should be used to create elements. | |
| 228 """ | |
| 1 | 229 |
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230 def __init__(self, namespace=None): |
| 28 | 231 """Create the factory, optionally bound to the given namespace. |
| 232 | |
| 233 @param namespace: the namespace URI for any created elements, or `None` | |
| 234 for no namespace | |
| 235 """ | |
| 20 | 236 if namespace and not isinstance(namespace, Namespace): |
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237 namespace = Namespace(namespace) |
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238 self.namespace = namespace |
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239 |
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240 def __call__(self, *args): |
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241 return Fragment()(*args) |
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242 |
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243 def __getitem__(self, namespace): |
| 28 | 244 """Return a new factory that is bound to the specified namespace.""" |
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245 return ElementFactory(namespace) |
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246 |
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247 def __getattr__(self, name): |
| 28 | 248 """Create an `Element` with the given name.""" |
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249 return Element(self.namespace and self.namespace[name] or name) |
| 1 | 250 |
| 251 | |
| 252 tag = ElementFactory() |