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annotate markup/template.py @ 5:dbb08edbc615 trunk
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
| author | cmlenz |
|---|---|
| date | Sat, 03 Jun 2006 15:29:27 +0000 |
| parents | 5479aae32f5a |
| children | 71e8e645fe81 |
| rev | line source |
|---|---|
| 1 | 1 # -*- coding: utf-8 -*- |
| 2 # | |
| 3 # Copyright (C) 2006 Christopher Lenz | |
| 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://trac.edgewall.com/license.html. | |
| 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://projects.edgewall.com/trac/. | |
| 13 | |
| 14 """Template engine that is compatible with Kid (http://kid.lesscode.org) to a | |
| 15 certain extent. | |
| 16 | |
| 17 Differences include: | |
| 18 * No generation of Python code for a template; the template is "interpreted" | |
| 19 * No support for <?python ?> processing instructions | |
| 20 * Expressions are evaluated in a more flexible manner, meaning you can use e.g. | |
| 21 attribute access notation to access items in a dictionary, etc | |
| 22 * Use of XInclude and match templates instead of Kid's py:extends/py:layout | |
| 23 directives | |
| 24 * Real (thread-safe) search path support | |
| 25 * No dependency on ElementTree (due to the lack of pos info) | |
| 26 * The original pos of parse events is kept throughout the processing | |
| 27 pipeline, so that errors can be tracked back to a specific line/column in | |
| 28 the template file | |
| 29 * py:match directives use (basic) XPath expressions to match against input | |
| 30 nodes, making match templates more powerful while keeping the syntax simple | |
| 31 | |
| 32 Todo items: | |
| 33 * Improved error reporting | |
| 34 * Support for using directives as elements and not just as attributes, reducing | |
| 35 the need for wrapper elements with py:strip="" | |
| 36 * Support for py:choose/py:when/py:otherwise (similar to XSLT) | |
| 37 * Support for list comprehensions and generator expressions in expressions | |
| 38 | |
| 39 Random thoughts: | |
| 40 * Is there any need to support py:extends and/or py:layout? | |
| 41 * Could we generate byte code from expressions? | |
| 42 """ | |
| 43 | |
| 44 import compiler | |
| 45 from itertools import chain | |
| 46 import os | |
| 47 import re | |
| 48 from StringIO import StringIO | |
| 49 | |
| 50 from markup.core import Attributes, Stream | |
| 51 from markup.eval import Expression | |
| 52 from markup.filters import EvalFilter, IncludeFilter, MatchFilter, \ | |
| 53 WhitespaceFilter | |
| 54 from markup.input import HTML, XMLParser, XML | |
| 55 | |
| 56 __all__ = ['Context', 'BadDirectiveError', 'TemplateError', | |
| 57 'TemplateSyntaxError', 'TemplateNotFound', 'Template', | |
| 58 'TemplateLoader'] | |
| 59 | |
| 60 | |
| 61 class TemplateError(Exception): | |
| 62 """Base exception class for errors related to template processing.""" | |
| 63 | |
| 64 | |
| 65 class TemplateSyntaxError(TemplateError): | |
| 66 """Exception raised when an expression in a template causes a Python syntax | |
| 67 error.""" | |
| 68 | |
| 69 def __init__(self, message, filename='<string>', lineno=-1, offset=-1): | |
| 70 if isinstance(message, SyntaxError) and message.lineno is not None: | |
| 71 message = str(message).replace(' (line %d)' % message.lineno, '') | |
| 72 TemplateError.__init__(self, message) | |
| 73 self.filename = filename | |
| 74 self.lineno = lineno | |
| 75 self.offset = offset | |
| 76 | |
| 77 | |
| 78 class BadDirectiveError(TemplateSyntaxError): | |
| 79 """Exception raised when an unknown directive is encountered when parsing | |
| 80 a template. | |
| 81 | |
| 82 An unknown directive is any attribute using the namespace for directives, | |
| 83 with a local name that doesn't match any registered directive. | |
| 84 """ | |
| 85 | |
| 86 def __init__(self, name, filename='<string>', lineno=-1): | |
| 87 TemplateSyntaxError.__init__(self, 'Bad directive "%s"' % name.localname, | |
| 88 filename, lineno) | |
| 89 | |
| 90 | |
| 91 class TemplateNotFound(TemplateError): | |
| 92 """Exception raised when a specific template file could not be found.""" | |
| 93 | |
| 94 def __init__(self, name, search_path): | |
| 95 TemplateError.__init__(self, 'Template "%s" not found' % name) | |
| 96 self.search_path = search_path | |
| 97 | |
| 98 | |
| 99 class Context(object): | |
| 100 """A container for template input data. | |
| 101 | |
| 102 A context provides a stack of scopes. Template directives such as loops can | |
| 103 push a new scope on the stack with data that should only be available | |
| 104 inside the loop. When the loop terminates, that scope can get popped off | |
| 105 the stack again. | |
| 106 | |
| 107 >>> ctxt = Context(one='foo', other=1) | |
| 108 >>> ctxt.get('one') | |
| 109 'foo' | |
| 110 >>> ctxt.get('other') | |
| 111 1 | |
| 112 >>> ctxt.push(one='frost') | |
| 113 >>> ctxt.get('one') | |
| 114 'frost' | |
| 115 >>> ctxt.get('other') | |
| 116 1 | |
| 117 >>> ctxt.pop() | |
| 118 >>> ctxt.get('one') | |
| 119 'foo' | |
| 120 """ | |
| 121 | |
| 122 def __init__(self, **data): | |
| 123 self.stack = [data] | |
| 124 | |
| 125 def __getitem__(self, key): | |
| 126 """Get a variable's value, starting at the current context and going | |
| 127 upward. | |
| 128 """ | |
| 129 return self.get(key) | |
| 130 | |
| 131 def __repr__(self): | |
| 132 return repr(self.stack) | |
| 133 | |
| 134 def __setitem__(self, key, value): | |
| 135 """Set a variable in the current context.""" | |
| 136 self.stack[0][key] = value | |
| 137 | |
| 138 def get(self, key): | |
| 139 for frame in self.stack: | |
| 140 if key in frame: | |
| 141 return frame[key] | |
| 142 | |
| 143 def push(self, **data): | |
| 144 self.stack.insert(0, data) | |
| 145 | |
| 146 def pop(self): | |
| 147 assert self.stack, 'Pop from empty context stack' | |
| 148 self.stack.pop(0) | |
| 149 | |
| 150 | |
| 151 class Directive(object): | |
| 152 """Abstract base class for template directives. | |
| 153 | |
| 154 A directive is basically a callable that takes two parameters: `ctxt` is | |
| 155 the template data context, and `stream` is an iterable over the events that | |
| 156 the directive applies to. | |
| 157 | |
| 158 Directives can be "anonymous" or "registered". Registered directives can be | |
| 159 applied by the template author using an XML attribute with the | |
| 160 corresponding name in the template. Such directives should be subclasses of | |
| 161 this base class that can be instantiated with two parameters: `template` | |
| 162 is the `Template` instance, and `value` is the value of the directive | |
| 163 attribute. | |
| 164 | |
| 165 Anonymous directives are simply functions conforming to the protocol | |
| 166 described above, and can only be applied programmatically (for example by | |
| 167 template filters). | |
| 168 """ | |
| 169 __slots__ = ['expr'] | |
| 170 | |
| 171 def __init__(self, template, value, pos): | |
| 172 self.expr = value and Expression(value) or None | |
| 173 | |
| 174 def __call__(self, stream, ctxt): | |
| 175 raise NotImplementedError | |
| 176 | |
| 177 def __repr__(self): | |
| 178 expr = '' | |
| 179 if self.expr is not None: | |
| 180 expr = ' "%s"' % self.expr.source | |
| 181 return '<%s%s>' % (self.__class__.__name__, expr) | |
| 182 | |
| 183 | |
| 184 class AttrsDirective(Directive): | |
| 185 """Implementation of the `py:attrs` template directive. | |
| 186 | |
| 187 The value of the `py:attrs` attribute should be a dictionary. The keys and | |
| 188 values of that dictionary will be added as attributes to the element: | |
| 189 | |
| 190 >>> ctxt = Context(foo={'class': 'collapse'}) | |
| 191 >>> tmpl = Template('''<ul xmlns:py="http://purl.org/kid/ns#"> | |
| 192 ... <li py:attrs="foo">Bar</li> | |
| 193 ... </ul>''') | |
| 194 >>> print tmpl.generate(ctxt) | |
| 195 <ul> | |
| 196 <li class="collapse">Bar</li> | |
| 197 </ul> | |
| 198 | |
| 199 If the value evaluates to `None` (or any other non-truth value), no | |
| 200 attributes are added: | |
| 201 | |
| 202 >>> ctxt = Context(foo=None) | |
| 203 >>> print tmpl.generate(ctxt) | |
| 204 <ul> | |
| 205 <li>Bar</li> | |
| 206 </ul> | |
| 207 """ | |
| 208 def __call__(self, stream, ctxt): | |
| 209 kind, (tag, attrib), pos = stream.next() | |
| 210 attrs = self.expr.evaluate(ctxt) | |
| 211 if attrs: | |
|
5
dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
parents:
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212 attrib = Attributes(attrib[:]) |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
parents:
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changeset
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213 if not isinstance(attrs, list): # assume it's a dict |
|
dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
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214 attrs = attrs.items() |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
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215 for name, value in attrs: |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
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216 if value is None: |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
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217 attrib.remove(name) |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
parents:
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218 else: |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
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219 attrib.set(name, unicode(value).strip()) |
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dbb08edbc615
Improved `py:attrs` directive so that it removes existing attributes if they evaluate to `None` (AFAICT matching Kid behavior).
cmlenz
parents:
1
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220 yield kind, (tag, attrib), pos |
| 1 | 221 for event in stream: |
| 222 yield event | |
| 223 | |
| 224 | |
| 225 class ContentDirective(Directive): | |
| 226 """Implementation of the `py:content` template directive. | |
| 227 | |
| 228 This directive replaces the content of the element with the result of | |
| 229 evaluating the value of the `py:content` attribute: | |
| 230 | |
| 231 >>> ctxt = Context(bar='Bye') | |
| 232 >>> tmpl = Template('''<ul xmlns:py="http://purl.org/kid/ns#"> | |
| 233 ... <li py:content="bar">Hello</li> | |
| 234 ... </ul>''') | |
| 235 >>> print tmpl.generate(ctxt) | |
| 236 <ul> | |
| 237 <li>Bye</li> | |
| 238 </ul> | |
| 239 """ | |
| 240 def __call__(self, stream, ctxt): | |
| 241 kind, data, pos = stream.next() | |
| 242 if kind is Stream.START: | |
| 243 yield kind, data, pos # emit start tag | |
| 244 yield Stream.EXPR, self.expr, pos | |
| 245 previous = None | |
| 246 try: | |
| 247 while True: | |
| 248 previous = stream.next() | |
| 249 except StopIteration: | |
| 250 if previous is not None: | |
| 251 yield previous | |
| 252 | |
| 253 | |
| 254 class DefDirective(Directive): | |
| 255 """Implementation of the `py:def` template directive. | |
| 256 | |
| 257 This directive can be used to create "Named Template Functions", which | |
| 258 are template snippets that are not actually output during normal | |
| 259 processing, but rather can be expanded from expressions in other places | |
| 260 in the template. | |
| 261 | |
| 262 A named template function can be used just like a normal Python function | |
| 263 from template expressions: | |
| 264 | |
| 265 >>> ctxt = Context(bar='Bye') | |
| 266 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 267 ... <p py:def="echo(greeting, name='world')" class="message"> | |
| 268 ... ${greeting}, ${name}! | |
| 269 ... </p> | |
| 270 ... ${echo('hi', name='you')} | |
| 271 ... </div>''') | |
| 272 >>> print tmpl.generate(ctxt) | |
| 273 <div> | |
| 274 <p class="message"> | |
| 275 hi, you! | |
| 276 </p> | |
| 277 </div> | |
| 278 | |
| 279 >>> ctxt = Context(bar='Bye') | |
| 280 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 281 ... <p py:def="echo(greeting, name='world')" class="message"> | |
| 282 ... ${greeting}, ${name}! | |
| 283 ... </p> | |
| 284 ... <div py:replace="echo('hello')"></div> | |
| 285 ... </div>''') | |
| 286 >>> print tmpl.generate(ctxt) | |
| 287 <div> | |
| 288 <p class="message"> | |
| 289 hello, world! | |
| 290 </p> | |
| 291 </div> | |
| 292 """ | |
| 293 __slots__ = ['name', 'args', 'defaults', 'stream'] | |
| 294 | |
| 295 def __init__(self, template, args, pos): | |
| 296 Directive.__init__(self, template, None, pos) | |
| 297 ast = compiler.parse(args, 'eval').node | |
| 298 self.args = [] | |
| 299 self.defaults = {} | |
| 300 if isinstance(ast, compiler.ast.CallFunc): | |
| 301 self.name = ast.node.name | |
| 302 for arg in ast.args: | |
| 303 if isinstance(arg, compiler.ast.Keyword): | |
| 304 self.args.append(arg.name) | |
| 305 self.defaults[arg.name] = arg.expr.value | |
| 306 else: | |
| 307 self.args.append(arg.name) | |
| 308 else: | |
| 309 self.name = ast.name | |
| 310 self.stream = [] | |
| 311 | |
| 312 def __call__(self, stream, ctxt): | |
| 313 self.stream = list(stream) | |
| 314 ctxt[self.name] = lambda *args, **kwargs: self._exec(ctxt, *args, | |
| 315 **kwargs) | |
| 316 return [] | |
| 317 | |
| 318 def _exec(self, ctxt, *args, **kwargs): | |
| 319 scope = {} | |
| 320 args = list(args) # make mutable | |
| 321 for name in self.args: | |
| 322 if args: | |
| 323 scope[name] = args.pop(0) | |
| 324 else: | |
| 325 scope[name] = kwargs.pop(name, self.defaults.get(name)) | |
| 326 ctxt.push(**scope) | |
| 327 for event in self.stream: | |
| 328 yield event | |
| 329 ctxt.pop() | |
| 330 | |
| 331 | |
| 332 class ForDirective(Directive): | |
| 333 """Implementation of the `py:for` template directive. | |
| 334 | |
| 335 >>> ctxt = Context(items=[1, 2, 3]) | |
| 336 >>> tmpl = Template('''<ul xmlns:py="http://purl.org/kid/ns#"> | |
| 337 ... <li py:for="item in items">${item}</li> | |
| 338 ... </ul>''') | |
| 339 >>> print tmpl.generate(ctxt) | |
| 340 <ul> | |
| 341 <li>1</li><li>2</li><li>3</li> | |
| 342 </ul> | |
| 343 """ | |
| 344 __slots__ = ['targets'] | |
| 345 | |
| 346 def __init__(self, template, value, pos): | |
| 347 targets, expr_source = value.split(' in ', 1) | |
| 348 self.targets = [str(name.strip()) for name in targets.split(',')] | |
| 349 Directive.__init__(self, template, expr_source, pos) | |
| 350 | |
| 351 def __call__(self, stream, ctxt): | |
| 352 iterable = self.expr.evaluate(ctxt, []) | |
| 353 if iterable is not None: | |
| 354 stream = list(stream) | |
| 355 for item in iter(iterable): | |
| 356 if len(self.targets) == 1: | |
| 357 item = [item] | |
| 358 scope = {} | |
| 359 for idx, name in enumerate(self.targets): | |
| 360 scope[name] = item[idx] | |
| 361 ctxt.push(**scope) | |
| 362 for event in stream: | |
| 363 yield event | |
| 364 ctxt.pop() | |
| 365 | |
| 366 def __repr__(self): | |
| 367 return '<%s "%s in %s">' % (self.__class__.__name__, | |
| 368 ', '.join(self.targets), self.expr.source) | |
| 369 | |
| 370 | |
| 371 class IfDirective(Directive): | |
| 372 """Implementation of the `py:if` template directive. | |
| 373 | |
| 374 >>> ctxt = Context(foo=True, bar='Hello') | |
| 375 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 376 ... <b py:if="foo">${bar}</b> | |
| 377 ... </div>''') | |
| 378 >>> print tmpl.generate(ctxt) | |
| 379 <div> | |
| 380 <b>Hello</b> | |
| 381 </div> | |
| 382 """ | |
| 383 def __call__(self, stream, ctxt): | |
| 384 if self.expr.evaluate(ctxt): | |
| 385 return stream | |
| 386 return [] | |
| 387 | |
| 388 | |
| 389 class MatchDirective(Directive): | |
| 390 """Implementation of the `py:match` template directive. | |
| 391 | |
| 392 >>> ctxt = Context() | |
| 393 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 394 ... <span py:match="div/greeting"> | |
| 395 ... Hello ${select('@name')} | |
| 396 ... </span> | |
| 397 ... <greeting name="Dude" /> | |
| 398 ... </div>''') | |
| 399 >>> print tmpl.generate(ctxt) | |
| 400 <div> | |
| 401 <span> | |
| 402 Hello Dude | |
| 403 </span> | |
| 404 </div> | |
| 405 """ | |
| 406 __slots__ = ['path', 'stream'] | |
| 407 | |
| 408 def __init__(self, template, value, pos): | |
| 409 Directive.__init__(self, template, None, pos) | |
| 410 template.filters.append(MatchFilter(value, self._handle_match)) | |
| 411 self.path = value | |
| 412 self.stream = [] | |
| 413 | |
| 414 def __call__(self, stream, ctxt): | |
| 415 self.stream = list(stream) | |
| 416 return [] | |
| 417 | |
| 418 def __repr__(self): | |
| 419 return '<%s "%s">' % (self.__class__.__name__, self.path) | |
| 420 | |
| 421 def _handle_match(self, orig_stream, ctxt): | |
| 422 ctxt.push(select=lambda path: Stream(orig_stream).select(path)) | |
| 423 for event in self.stream: | |
| 424 yield event | |
| 425 ctxt.pop() | |
| 426 | |
| 427 | |
| 428 class ReplaceDirective(Directive): | |
| 429 """Implementation of the `py:replace` template directive. | |
| 430 | |
| 431 >>> ctxt = Context(bar='Bye') | |
| 432 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 433 ... <span py:replace="bar">Hello</span> | |
| 434 ... </div>''') | |
| 435 >>> print tmpl.generate(ctxt) | |
| 436 <div> | |
| 437 Bye | |
| 438 </div> | |
| 439 | |
| 440 This directive is equivalent to `py:content` combined with `py:strip`, | |
| 441 providing a less verbose way to achieve the same effect: | |
| 442 | |
| 443 >>> ctxt = Context(bar='Bye') | |
| 444 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 445 ... <span py:content="bar" py:strip="">Hello</span> | |
| 446 ... </div>''') | |
| 447 >>> print tmpl.generate(ctxt) | |
| 448 <div> | |
| 449 Bye | |
| 450 </div> | |
| 451 """ | |
| 452 def __call__(self, stream, ctxt): | |
| 453 kind, data, pos = stream.next() | |
| 454 yield Stream.EXPR, self.expr, pos | |
| 455 | |
| 456 | |
| 457 class StripDirective(Directive): | |
| 458 """Implementation of the `py:strip` template directive. | |
| 459 | |
| 460 When the value of the `py:strip` attribute evaluates to `True`, the element | |
| 461 is stripped from the output | |
| 462 | |
| 463 >>> ctxt = Context() | |
| 464 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 465 ... <div py:strip="True"><b>foo</b></div> | |
| 466 ... </div>''') | |
| 467 >>> print tmpl.generate(ctxt) | |
| 468 <div> | |
| 469 <b>foo</b> | |
| 470 </div> | |
| 471 | |
| 472 On the other hand, when the attribute evaluates to `False`, the element is | |
| 473 not stripped: | |
| 474 | |
| 475 >>> ctxt = Context() | |
| 476 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 477 ... <div py:strip="False"><b>foo</b></div> | |
| 478 ... </div>''') | |
| 479 >>> print tmpl.generate(ctxt) | |
| 480 <div> | |
| 481 <div><b>foo</b></div> | |
| 482 </div> | |
| 483 | |
| 484 Leaving the attribute value empty is equivalent to a truth value: | |
| 485 | |
| 486 >>> ctxt = Context() | |
| 487 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 488 ... <div py:strip=""><b>foo</b></div> | |
| 489 ... </div>''') | |
| 490 >>> print tmpl.generate(ctxt) | |
| 491 <div> | |
| 492 <b>foo</b> | |
| 493 </div> | |
| 494 | |
| 495 This directive is particulary interesting for named template functions or | |
| 496 match templates that do not generate a top-level element: | |
| 497 | |
| 498 >>> ctxt = Context() | |
| 499 >>> tmpl = Template('''<div xmlns:py="http://purl.org/kid/ns#"> | |
| 500 ... <div py:def="echo(what)" py:strip=""> | |
| 501 ... <b>${what}</b> | |
| 502 ... </div> | |
| 503 ... ${echo('foo')} | |
| 504 ... </div>''') | |
| 505 >>> print tmpl.generate(ctxt) | |
| 506 <div> | |
| 507 <b>foo</b> | |
| 508 </div> | |
| 509 """ | |
| 510 def __call__(self, stream, ctxt): | |
| 511 if self.expr: | |
| 512 strip = self.expr.evaluate(ctxt) | |
| 513 else: | |
| 514 strip = True | |
| 515 if strip: | |
| 516 stream.next() # skip start tag | |
| 517 # can ignore StopIteration since it will just break from this | |
| 518 # generator | |
| 519 previous = stream.next() | |
| 520 for event in stream: | |
| 521 yield previous | |
| 522 previous = event | |
| 523 else: | |
| 524 for event in stream: | |
| 525 yield event | |
| 526 | |
| 527 | |
| 528 class Template(object): | |
| 529 """Can parse a template and transform it into the corresponding output | |
| 530 based on context data. | |
| 531 """ | |
| 532 NAMESPACE = 'http://purl.org/kid/ns#' | |
| 533 | |
| 534 directives = [('def', DefDirective), | |
| 535 ('match', MatchDirective), | |
| 536 ('for', ForDirective), | |
| 537 ('if', IfDirective), | |
| 538 ('replace', ReplaceDirective), | |
| 539 ('content', ContentDirective), | |
| 540 ('attrs', AttrsDirective), | |
| 541 ('strip', StripDirective)] | |
| 542 _dir_by_name = dict(directives) | |
| 543 _dir_order = [directive[1] for directive in directives] | |
| 544 | |
| 545 def __init__(self, source, filename=None): | |
| 546 """Initialize a template from either a string or a file-like object.""" | |
| 547 if isinstance(source, basestring): | |
| 548 self.source = StringIO(source) | |
| 549 else: | |
| 550 self.source = source | |
| 551 self.filename = filename or '<string>' | |
| 552 | |
| 553 self.pre_filters = [EvalFilter()] | |
| 554 self.filters = [] | |
| 555 self.post_filters = [WhitespaceFilter()] | |
| 556 self.parse() | |
| 557 | |
| 558 def __repr__(self): | |
| 559 return '<%s "%s">' % (self.__class__.__name__, | |
| 560 os.path.basename(self.filename)) | |
| 561 | |
| 562 def parse(self): | |
| 563 """Parse the template. | |
| 564 | |
| 565 The parsing stage parses the XML template and constructs a list of | |
| 566 directives that will be executed in the render stage. The input is | |
| 567 split up into literal output (markup that does not depend on the | |
| 568 context data) and actual directives (commands or variable | |
| 569 substitution). | |
| 570 """ | |
| 571 stream = [] # list of events of the "compiled" template | |
| 572 dirmap = {} # temporary mapping of directives to elements | |
| 573 ns_prefix = {} | |
| 574 depth = 0 | |
| 575 | |
| 576 for kind, data, pos in XMLParser(self.source): | |
| 577 | |
| 578 if kind is Stream.START_NS: | |
| 579 # Strip out the namespace declaration for template directives | |
| 580 prefix, uri = data | |
| 581 if uri == self.NAMESPACE: | |
| 582 ns_prefix[prefix] = uri | |
| 583 else: | |
| 584 stream.append((kind, data, pos)) | |
| 585 | |
| 586 elif kind is Stream.END_NS: | |
| 587 if data in ns_prefix: | |
| 588 del ns_prefix[data] | |
| 589 else: | |
| 590 stream.append((kind, data, pos)) | |
| 591 | |
| 592 elif kind is Stream.START: | |
| 593 # Record any directive attributes in start tags | |
| 594 tag, attrib = data | |
| 595 directives = [] | |
| 596 new_attrib = [] | |
| 597 for name, value in attrib: | |
| 598 if name.namespace == self.NAMESPACE: | |
| 599 cls = self._dir_by_name.get(name.localname) | |
| 600 if cls is None: | |
| 601 raise BadDirectiveError(name, self.filename, pos[0]) | |
| 602 else: | |
| 603 directives.append(cls(self, value, pos)) | |
| 604 else: | |
| 605 value = list(self._interpolate(value, *pos)) | |
| 606 new_attrib.append((name, value)) | |
| 607 if directives: | |
| 608 directives.sort(lambda a, b: cmp(self._dir_order.index(a.__class__), | |
| 609 self._dir_order.index(b.__class__))) | |
| 610 dirmap[(depth, tag)] = (directives, len(stream)) | |
| 611 | |
| 612 stream.append((kind, (tag, Attributes(new_attrib)), pos)) | |
| 613 depth += 1 | |
| 614 | |
| 615 elif kind is Stream.END: | |
| 616 depth -= 1 | |
| 617 stream.append((kind, data, pos)) | |
| 618 | |
| 619 # If there have have directive attributes with the corresponding | |
| 620 # start tag, move the events inbetween into a "subprogram" | |
| 621 if (depth, data) in dirmap: | |
| 622 directives, start_offset = dirmap.pop((depth, data)) | |
| 623 substream = stream[start_offset:] | |
| 624 stream[start_offset:] = [(Stream.SUB, | |
| 625 (directives, substream), pos)] | |
| 626 | |
| 627 elif kind is Stream.TEXT: | |
| 628 for kind, data, pos in self._interpolate(data, *pos): | |
| 629 stream.append((kind, data, pos)) | |
| 630 | |
| 631 else: | |
| 632 stream.append((kind, data, pos)) | |
| 633 | |
| 634 self.stream = stream | |
| 635 | |
| 636 def generate(self, ctxt): | |
| 637 """Transform the template based on the given context data.""" | |
| 638 | |
| 639 def _transform(stream): | |
| 640 # Apply pre and runtime filters | |
| 641 for filter_ in chain(self.pre_filters, self.filters): | |
| 642 stream = filter_(iter(stream), ctxt) | |
| 643 | |
| 644 try: | |
| 645 for kind, data, pos in stream: | |
| 646 | |
| 647 if kind is Stream.SUB: | |
| 648 # This event is a list of directives and a list of | |
| 649 # nested events to which those directives should be | |
| 650 # applied | |
| 651 directives, substream = data | |
| 652 directives.reverse() | |
| 653 for directive in directives: | |
| 654 substream = directive(iter(substream), ctxt) | |
| 655 for event in _transform(iter(substream)): | |
| 656 yield event | |
| 657 | |
| 658 else: | |
| 659 yield kind, data, pos | |
| 660 except SyntaxError, err: | |
| 661 raise TemplateSyntaxError(err, self.filename, pos[0], | |
| 662 pos[1] + (err.offset or 0)) | |
| 663 | |
| 664 stream = _transform(self.stream) | |
| 665 | |
| 666 # Apply post-filters | |
| 667 for filter_ in self.post_filters: | |
| 668 stream = filter_(iter(stream), ctxt) | |
| 669 | |
| 670 return Stream(stream) | |
| 671 | |
| 672 _FULL_EXPR_RE = re.compile(r'(?<!\$)\$\{(.+?)\}') | |
| 673 _SHORT_EXPR_RE = re.compile(r'(?<!\$)\$([a-zA-Z][a-zA-Z0-9_\.]*)') | |
| 674 | |
| 675 def _interpolate(cls, text, lineno=-1, offset=-1): | |
| 676 """Parse the given string and extract expressions. | |
| 677 | |
| 678 This method returns a list containing both literal text and `Expression` | |
| 679 objects. | |
| 680 | |
| 681 @param text: the text to parse | |
| 682 @param lineno: the line number at which the text was found (optional) | |
| 683 @param offset: the column number at which the text starts in the source | |
| 684 (optional) | |
| 685 """ | |
| 686 patterns = [cls._FULL_EXPR_RE, cls._SHORT_EXPR_RE] | |
| 687 def _interpolate(text): | |
| 688 for idx, group in enumerate(patterns.pop(0).split(text)): | |
| 689 if idx % 2: | |
| 690 yield Stream.EXPR, Expression(group), (lineno, offset) | |
| 691 elif group: | |
| 692 if patterns: | |
| 693 for result in _interpolate(group): | |
| 694 yield result | |
| 695 else: | |
| 696 yield Stream.TEXT, group.replace('$$', '$'), \ | |
| 697 (lineno, offset) | |
| 698 return _interpolate(text) | |
| 699 _interpolate = classmethod(_interpolate) | |
| 700 | |
| 701 | |
| 702 class TemplateLoader(object): | |
| 703 """Responsible for loading templates from files on the specified search | |
| 704 path. | |
| 705 | |
| 706 >>> import tempfile | |
| 707 >>> fd, path = tempfile.mkstemp(suffix='.html', prefix='template') | |
| 708 >>> os.write(fd, '<p>$var</p>') | |
| 709 11 | |
| 710 >>> os.close(fd) | |
| 711 | |
| 712 The template loader accepts a list of directory paths that are then used | |
| 713 when searching for template files, in the given order: | |
| 714 | |
| 715 >>> loader = TemplateLoader([os.path.dirname(path)]) | |
| 716 | |
| 717 The `load()` method first checks the template cache whether the requested | |
| 718 template has already been loaded. If not, it attempts to locate the | |
| 719 template file, and returns the corresponding `Template` object: | |
| 720 | |
| 721 >>> template = loader.load(os.path.basename(path)) | |
| 722 >>> isinstance(template, Template) | |
| 723 True | |
| 724 | |
| 725 Template instances are cached: requesting a template with the same name | |
| 726 results in the same instance being returned: | |
| 727 | |
| 728 >>> loader.load(os.path.basename(path)) is template | |
| 729 True | |
| 730 """ | |
| 731 def __init__(self, search_path=None, auto_reload=False): | |
| 732 """Create the template laoder. | |
| 733 | |
| 734 @param search_path: a list of absolute path names that should be | |
| 735 searched for template files | |
| 736 @param auto_reload: whether to check the last modification time of | |
| 737 template files, and reload them if they have changed | |
| 738 """ | |
| 739 self.search_path = search_path | |
| 740 if self.search_path is None: | |
| 741 self.search_path = [] | |
| 742 self.auto_reload = auto_reload | |
| 743 self._cache = {} | |
| 744 self._mtime = {} | |
| 745 | |
| 746 def load(self, filename): | |
| 747 """Load the template with the given name. | |
| 748 | |
| 749 This method searches the search path trying to locate a template | |
| 750 matching the given name. If no such template is found, a | |
| 751 `TemplateNotFound` exception is raised. Otherwise, a `Template` object | |
| 752 representing the requested template is returned. | |
| 753 | |
| 754 Template searches are cached to avoid having to parse the same template | |
| 755 file more than once. Thus, subsequent calls of this method with the | |
| 756 same template file name will return the same `Template` object. | |
| 757 | |
| 758 @param filename: the relative path of the template file to load | |
| 759 """ | |
| 760 filename = os.path.normpath(filename) | |
| 761 try: | |
| 762 tmpl = self._cache[filename] | |
| 763 if not self.auto_reload or \ | |
| 764 os.path.getmtime(tmpl.filename) == self._mtime[filename]: | |
| 765 return tmpl | |
| 766 except KeyError: | |
| 767 pass | |
| 768 for dirname in self.search_path: | |
| 769 filepath = os.path.join(dirname, filename) | |
| 770 try: | |
| 771 fileobj = file(filepath, 'rt') | |
| 772 try: | |
| 773 tmpl = Template(fileobj, filename=filepath) | |
| 774 tmpl.pre_filters.append(IncludeFilter(self)) | |
| 775 finally: | |
| 776 fileobj.close() | |
| 777 self._cache[filename] = tmpl | |
| 778 self._mtime[filename] = os.path.getmtime(filepath) | |
| 779 return tmpl | |
| 780 except IOError: | |
| 781 continue | |
| 782 raise TemplateNotFound(filename, self.search_path) |