tornado/template.py - vendor/opensource/tornado - Git at Google

 #!/usr/bin/env python
 #
 # Copyright 2009 Facebook
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
 # not use this file except in compliance with the License. You may obtain
 # a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.

 """A simple template system that compiles templates to Python code.

 Basic usage looks like::

     t = template.Template("<html>{{ myvalue }}</html>")
     print t.generate(myvalue="XXX")

 Loader is a class that loads templates from a root directory and caches
 the compiled templates::

     loader = template.Loader("/home/btaylor")
     print loader.load("test.html").generate(myvalue="XXX")

 We compile all templates to raw Python. Error-reporting is currently... uh,
 interesting. Syntax for the templates::

     ### base.html
     <html>
       <head>
         <title>{% block title %}Default title{% end %}</title>
       </head>
       <body>
         <ul>
           {% for student in students %}
             {% block student %}
               <li>{{ escape(student.name) }}</li>
             {% end %}
           {% end %}
         </ul>
       </body>
     </html>

     ### bold.html
     {% extends "base.html" %}

     {% block title %}A bolder title{% end %}

     {% block student %}
       <li><span style="bold">{{ escape(student.name) }}</span></li>
     {% end %}

 Unlike most other template systems, we do not put any restrictions on the
 expressions you can include in your statements. if and for blocks get
 translated exactly into Python, do you can do complex expressions like::

    {% for student in [p for p in people if p.student and p.age > 23] %}
      <li>{{ escape(student.name) }}</li>
    {% end %}

 Translating directly to Python means you can apply functions to expressions
 easily, like the escape() function in the examples above. You can pass
 functions in to your template just like any other variable::

    ### Python code
    def add(x, y):
       return x + y
    template.execute(add=add)

    ### The template
    {{ add(1, 2) }}

 We provide the functions escape(), url_escape(), json_encode(), and squeeze()
 to all templates by default.

 Typical applications do not create `Template` or `Loader` instances by
 hand, but instead use the `render` and `render_string` methods of
 `tornado.web.RequestHandler`, which load templates automatically based
 on the ``template_path`` `Application` setting.
 """

 from __future__ import with_statement

 import cStringIO
 import datetime
 import logging
 import os.path
 import re

 from tornado import escape
 from tornado.util import bytes_type

 _DEFAULT_AUTOESCAPE = "xhtml_escape"
 _UNSET = object()

 class Template(object):
     """A compiled template.

     We compile into Python from the given template_string. You can generate
     the template from variables with generate().
     """
     def __init__(self, template_string, name="<string>", loader=None,
                  compress_whitespace=None, autoescape=_UNSET):
         self.name = name
         if compress_whitespace is None:
             compress_whitespace = name.endswith(".html") or \
                 name.endswith(".js")
         if autoescape is not _UNSET:
             self.autoescape = autoescape
         elif loader:
             self.autoescape = loader.autoescape
         else:
             self.autoescape = _DEFAULT_AUTOESCAPE
         reader = _TemplateReader(name, escape.native_str(template_string))
         self.file = _File(_parse(reader, self))
         self.code = self._generate_python(loader, compress_whitespace)
         try:
             self.compiled = compile(self.code, "<template %s>" % self.name,
                                     "exec")
         except:
             formatted_code = _format_code(self.code).rstrip()
             logging.error("%s code:\n%s", self.name, formatted_code)
             raise

     def generate(self, **kwargs):
         """Generate this template with the given arguments."""
         namespace = {
             "escape": escape.xhtml_escape,
             "xhtml_escape": escape.xhtml_escape,
             "url_escape": escape.url_escape,
             "json_encode": escape.json_encode,
             "squeeze": escape.squeeze,
             "linkify": escape.linkify,
             "datetime": datetime,
             "_utf8": escape.utf8,  # for internal use
             "_string_types": (unicode, bytes_type),
         }
         namespace.update(kwargs)
         exec self.compiled in namespace
         execute = namespace["_execute"]
         try:
             return execute()
         except:
             formatted_code = _format_code(self.code).rstrip()
             logging.error("%s code:\n%s", self.name, formatted_code)
             raise

     def _generate_python(self, loader, compress_whitespace):
         buffer = cStringIO.StringIO()
         try:
             # named_blocks maps from names to _NamedBlock objects
             named_blocks = {}
             ancestors = self._get_ancestors(loader)
             ancestors.reverse()
             for ancestor in ancestors:
                 ancestor.find_named_blocks(loader, named_blocks)
             self.file.find_named_blocks(loader, named_blocks)
             writer = _CodeWriter(buffer, named_blocks, loader, self,
                                  compress_whitespace)
             ancestors[0].generate(writer)
             return buffer.getvalue()
         finally:
             buffer.close()

     def _get_ancestors(self, loader):
         ancestors = [self.file]
         for chunk in self.file.body.chunks:
             if isinstance(chunk, _ExtendsBlock):
                 if not loader:
                     raise ParseError("{% extends %} block found, but no "
                                      "template loader")
                 template = loader.load(chunk.name, self.name)
                 ancestors.extend(template._get_ancestors(loader))
         return ancestors


 class BaseLoader(object):
     """Base class for template loaders."""
     def __init__(self, root_directory, autoescape=_DEFAULT_AUTOESCAPE):
         """Creates a template loader.

         root_directory may be the empty string if this loader does not
         use the filesystem.

         autoescape must be either None or a string naming a function
         in the template namespace, such as "xhtml_escape".
         """
         self.root = os.path.abspath(root_directory)
         self.autoescape = autoescape
         self.templates = {}

     def reset(self):
         """Resets the cache of compiled templates."""
         self.templates = {}

     def resolve_path(self, name, parent_path=None):
         """Converts a possibly-relative path to absolute (used internally)."""
         if parent_path and not parent_path.startswith("<") and \
            not parent_path.startswith("/") and \
            not name.startswith("/"):
             current_path = os.path.join(self.root, parent_path)
             file_dir = os.path.dirname(os.path.abspath(current_path))
             relative_path = os.path.abspath(os.path.join(file_dir, name))
             if relative_path.startswith(self.root):
                 name = relative_path[len(self.root) + 1:]
         return name

     def load(self, name, parent_path=None):
         """Loads a template."""
         name = self.resolve_path(name, parent_path=parent_path)
         if name not in self.templates:
             self.templates[name] = self._create_template(name)
         return self.templates[name]

     def _create_template(self, name):
         raise NotImplementedError()

 class Loader(BaseLoader):
     """A template loader that loads from a single root directory.

     You must use a template loader to use template constructs like
     {% extends %} and {% include %}. Loader caches all templates after
     they are loaded the first time.
     """
     def __init__(self, root_directory, **kwargs):
         super(Loader, self).__init__(root_directory, **kwargs)

     def _create_template(self, name):
         path = os.path.join(self.root, name)
         f = open(path, "r")
         template = Template(f.read(), name=name, loader=self)
         f.close()
         return template


 class DictLoader(BaseLoader):
     """A template loader that loads from a dictionary."""
     def __init__(self, dict, **kwargs):
         super(DictLoader, self).__init__("", **kwargs)
         self.dict = dict

     def _create_template(self, name):
         return Template(self.dict[name], name=name, loader=self)


 class _Node(object):
     def each_child(self):
         return ()

     def generate(self, writer):
         raise NotImplementedError()

     def find_named_blocks(self, loader, named_blocks):
         for child in self.each_child():
             child.find_named_blocks(loader, named_blocks)


 class _File(_Node):
     def __init__(self, body):
         self.body = body

     def generate(self, writer):
         writer.write_line("def _execute():")
         with writer.indent():
             writer.write_line("_buffer = []")
             self.body.generate(writer)
             writer.write_line("return _utf8('').join(_buffer)")

     def each_child(self):
         return (self.body,)


 class _ChunkList(_Node):
     def __init__(self, chunks):
         self.chunks = chunks

     def generate(self, writer):
         for chunk in self.chunks:
             chunk.generate(writer)

     def each_child(self):
         return self.chunks


 class _NamedBlock(_Node):
     def __init__(self, name, body, template):
         self.name = name
         self.body = body
         self.template = template

     def each_child(self):
         return (self.body,)

     def generate(self, writer):
         block = writer.named_blocks[self.name]
         old = writer.current_template
         writer.current_template = block.template
         block.body.generate(writer)
         writer.current_template = old

     def find_named_blocks(self, loader, named_blocks):
         named_blocks[self.name] = self
         _Node.find_named_blocks(self, loader, named_blocks)


 class _ExtendsBlock(_Node):
     def __init__(self, name):
         self.name = name


 class _IncludeBlock(_Node):
     def __init__(self, name, reader):
         self.name = name
         self.template_name = reader.name

     def find_named_blocks(self, loader, named_blocks):
         included = loader.load(self.name, self.template_name)
         included.file.find_named_blocks(loader, named_blocks)

     def generate(self, writer):
         included = writer.loader.load(self.name, self.template_name)
         old = writer.current_template
         writer.current_template = included
         included.file.body.generate(writer)
         writer.current_template = old


 class _ApplyBlock(_Node):
     def __init__(self, method, body=None):
         self.method = method
         self.body = body

     def each_child(self):
         return (self.body,)

     def generate(self, writer):
         method_name = "apply%d" % writer.apply_counter
         writer.apply_counter += 1
         writer.write_line("def %s():" % method_name)
         with writer.indent():
             writer.write_line("_buffer = []")
             self.body.generate(writer)
             writer.write_line("return _utf8('').join(_buffer)")
         writer.write_line("_buffer.append(%s(%s()))" % (
             self.method, method_name))


 class _ControlBlock(_Node):
     def __init__(self, statement, body=None):
         self.statement = statement
         self.body = body

     def each_child(self):
         return (self.body,)

     def generate(self, writer):
         writer.write_line("%s:" % self.statement)
         with writer.indent():
             self.body.generate(writer)


 class _IntermediateControlBlock(_Node):
     def __init__(self, statement):
         self.statement = statement

     def generate(self, writer):
         writer.write_line("%s:" % self.statement, writer.indent_size() - 1)


 class _Statement(_Node):
     def __init__(self, statement):
         self.statement = statement

     def generate(self, writer):
         writer.write_line(self.statement)


 class _Expression(_Node):
     def __init__(self, expression, raw=False):
         self.expression = expression
         self.raw = raw

     def generate(self, writer):
         writer.write_line("_tmp = %s" % self.expression)
         writer.write_line("if isinstance(_tmp, _string_types):"
                           " _tmp = _utf8(_tmp)")
         writer.write_line("else: _tmp = _utf8(str(_tmp))")
         if not self.raw and writer.current_template.autoescape is not None:
             # In python3 functions like xhtml_escape return unicode,
             # so we have to convert to utf8 again.
             writer.write_line("_tmp = _utf8(%s(_tmp))" %
                               writer.current_template.autoescape)
         writer.write_line("_buffer.append(_tmp)")

 class _Module(_Expression):
     def __init__(self, expression):
         super(_Module, self).__init__("modules." + expression,
                                       raw=True)

 class _Text(_Node):
     def __init__(self, value):
         self.value = value

     def generate(self, writer):
         value = self.value

         # Compress lots of white space to a single character. If the whitespace
         # breaks a line, have it continue to break a line, but just with a
         # single \n character
         if writer.compress_whitespace and "<pre>" not in value:
             value = re.sub(r"([\t ]+)", " ", value)
             value = re.sub(r"(\s*\n\s*)", "\n", value)

         if value:
             writer.write_line('_buffer.append(%r)' % escape.utf8(value))


 class ParseError(Exception):
     """Raised for template syntax errors."""
     pass


 class _CodeWriter(object):
     def __init__(self, file, named_blocks, loader, current_template,
                  compress_whitespace):
         self.file = file
         self.named_blocks = named_blocks
         self.loader = loader
         self.current_template = current_template
         self.compress_whitespace = compress_whitespace
         self.apply_counter = 0
         self._indent = 0

     def indent(self):
         return self

     def indent_size(self):
         return self._indent

     def __enter__(self):
         self._indent += 1
         return self

     def __exit__(self, *args):
         assert self._indent > 0
         self._indent -= 1

     def write_line(self, line, indent=None):
         if indent == None:
             indent = self._indent
         for i in xrange(indent):
             self.file.write("    ")
         print >> self.file, line


 class _TemplateReader(object):
     def __init__(self, name, text):
         self.name = name
         self.text = text
         self.line = 0
         self.pos = 0

     def find(self, needle, start=0, end=None):
         assert start >= 0, start
         pos = self.pos
         start += pos
         if end is None:
             index = self.text.find(needle, start)
         else:
             end += pos
             assert end >= start
             index = self.text.find(needle, start, end)
         if index != -1:
             index -= pos
         return index

     def consume(self, count=None):
         if count is None:
             count = len(self.text) - self.pos
         newpos = self.pos + count
         self.line += self.text.count("\n", self.pos, newpos)
         s = self.text[self.pos:newpos]
         self.pos = newpos
         return s

     def remaining(self):
         return len(self.text) - self.pos

     def __len__(self):
         return self.remaining()

     def __getitem__(self, key):
         if type(key) is slice:
             size = len(self)
             start, stop, step = key.indices(size)
             if start is None: start = self.pos
             else: start += self.pos
             if stop is not None: stop += self.pos
             return self.text[slice(start, stop, step)]
         elif key < 0:
             return self.text[key]
         else:
             return self.text[self.pos + key]

     def __str__(self):
         return self.text[self.pos:]


 def _format_code(code):
     lines = code.splitlines()
     format = "%%%dd  %%s\n" % len(repr(len(lines) + 1))
     return "".join([format % (i + 1, line) for (i, line) in enumerate(lines)])


 def _parse(reader, template, in_block=None):
     body = _ChunkList([])
     while True:
         # Find next template directive
         curly = 0
         while True:
             curly = reader.find("{", curly)
             if curly == -1 or curly + 1 == reader.remaining():
                 # EOF
                 if in_block:
                     raise ParseError("Missing {%% end %%} block for %s" %
                                      in_block)
                 body.chunks.append(_Text(reader.consume()))
                 return body
             # If the first curly brace is not the start of a special token,
             # start searching from the character after it
             if reader[curly + 1] not in ("{", "%"):
                 curly += 1
                 continue
             # When there are more than 2 curlies in a row, use the
             # innermost ones.  This is useful when generating languages
             # like latex where curlies are also meaningful
             if (curly + 2 < reader.remaining() and
                 reader[curly + 1] == '{' and reader[curly + 2] == '{'):
                 curly += 1
                 continue
             break

         # Append any text before the special token
         if curly > 0:
             body.chunks.append(_Text(reader.consume(curly)))

         start_brace = reader.consume(2)
         line = reader.line

         # Template directives may be escaped as "{{!" or "{%!".
         # In this case output the braces and consume the "!".
         # This is especially useful in conjunction with jquery templates,
         # which also use double braces.
         if reader.remaining() and reader[0] == "!":
             reader.consume(1)
             body.chunks.append(_Text(start_brace))
             continue

         # Expression
         if start_brace == "{{":
             end = reader.find("}}")
             if end == -1 or reader.find("\n", 0, end) != -1:
                 raise ParseError("Missing end expression }} on line %d" % line)
             contents = reader.consume(end).strip()
             reader.consume(2)
             if not contents:
                 raise ParseError("Empty expression on line %d" % line)
             body.chunks.append(_Expression(contents))
             continue

         # Block
         assert start_brace == "{%", start_brace
         end = reader.find("%}")
         if end == -1 or reader.find("\n", 0, end) != -1:
             raise ParseError("Missing end block %%} on line %d" % line)
         contents = reader.consume(end).strip()
         reader.consume(2)
         if not contents:
             raise ParseError("Empty block tag ({%% %%}) on line %d" % line)

         operator, space, suffix = contents.partition(" ")
         suffix = suffix.strip()

         # Intermediate ("else", "elif", etc) blocks
         intermediate_blocks = {
             "else": set(["if", "for", "while"]),
             "elif": set(["if"]),
             "except": set(["try"]),
             "finally": set(["try"]),
         }
         allowed_parents = intermediate_blocks.get(operator)
         if allowed_parents is not None:
             if not in_block:
                 raise ParseError("%s outside %s block" %
                             (operator, allowed_parents))
             if in_block not in allowed_parents:
                 raise ParseError("%s block cannot be attached to %s block" % (operator, in_block))
             body.chunks.append(_IntermediateControlBlock(contents))
             continue

         # End tag
         elif operator == "end":
             if not in_block:
                 raise ParseError("Extra {%% end %%} block on line %d" % line)
             return body

         elif operator in ("extends", "include", "set", "import", "from",
                           "comment", "autoescape", "raw", "module"):
             if operator == "comment":
                 continue
             if operator == "extends":
                 suffix = suffix.strip('"').strip("'")
                 if not suffix:
                     raise ParseError("extends missing file path on line %d" % line)
                 block = _ExtendsBlock(suffix)
             elif operator in ("import", "from"):
                 if not suffix:
                     raise ParseError("import missing statement on line %d" % line)
                 block = _Statement(contents)
             elif operator == "include":
                 suffix = suffix.strip('"').strip("'")
                 if not suffix:
                     raise ParseError("include missing file path on line %d" % line)
                 block = _IncludeBlock(suffix, reader)
             elif operator == "set":
                 if not suffix:
                     raise ParseError("set missing statement on line %d" % line)
                 block = _Statement(suffix)
             elif operator == "autoescape":
                 fn = suffix.strip()
                 if fn == "None": fn = None
                 template.autoescape = fn
                 continue
             elif operator == "raw":
                 block = _Expression(suffix, raw=True)
             elif operator == "module":
                 block = _Module(suffix)
             body.chunks.append(block)
             continue

         elif operator in ("apply", "block", "try", "if", "for", "while"):
             # parse inner body recursively
             block_body = _parse(reader, template, operator)
             if operator == "apply":
                 if not suffix:
                     raise ParseError("apply missing method name on line %d" % line)
                 block = _ApplyBlock(suffix, block_body)
             elif operator == "block":
                 if not suffix:
                     raise ParseError("block missing name on line %d" % line)
                 block = _NamedBlock(suffix, block_body, template)
             else:
                 block = _ControlBlock(contents, block_body)
             body.chunks.append(block)
             continue

         else:
             raise ParseError("unknown operator: %r" % operator)
	#!/usr/bin/env python
	#
	# Copyright 2009 Facebook
	#
	# Licensed under the Apache License, Version 2.0 (the "License"); you may
	# not use this file except in compliance with the License. You may obtain
	# a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	# License for the specific language governing permissions and limitations
	# under the License.

	"""A simple template system that compiles templates to Python code.

	Basic usage looks like::

	t = template.Template("<html>{{ myvalue }}</html>")
	print t.generate(myvalue="XXX")

	Loader is a class that loads templates from a root directory and caches
	the compiled templates::

	loader = template.Loader("/home/btaylor")
	print loader.load("test.html").generate(myvalue="XXX")

	We compile all templates to raw Python. Error-reporting is currently... uh,
	interesting. Syntax for the templates::

	### base.html
	<html>
	<head>
	<title>{% block title %}Default title{% end %}</title>
	</head>
	<body>
	<ul>
	{% for student in students %}
	{% block student %}
	<li>{{ escape(student.name) }}</li>
	{% end %}
	{% end %}
	</ul>
	</body>
	</html>

	### bold.html
	{% extends "base.html" %}

	{% block title %}A bolder title{% end %}

	{% block student %}
	<li><span style="bold">{{ escape(student.name) }}</span></li>
	{% end %}

	Unlike most other template systems, we do not put any restrictions on the
	expressions you can include in your statements. if and for blocks get
	translated exactly into Python, do you can do complex expressions like::

	{% for student in [p for p in people if p.student and p.age > 23] %}
	<li>{{ escape(student.name) }}</li>
	{% end %}

	Translating directly to Python means you can apply functions to expressions
	easily, like the escape() function in the examples above. You can pass
	functions in to your template just like any other variable::

	### Python code
	def add(x, y):
	return x + y
	template.execute(add=add)

	### The template
	{{ add(1, 2) }}

	We provide the functions escape(), url_escape(), json_encode(), and squeeze()
	to all templates by default.

	Typical applications do not create `Template` or `Loader` instances by
	hand, but instead use the `render` and `render_string` methods of
	`tornado.web.RequestHandler`, which load templates automatically based
	on the ``template_path`` `Application` setting.
	"""

	from __future__ import with_statement

	import cStringIO
	import datetime
	import logging
	import os.path
	import re

	from tornado import escape
	from tornado.util import bytes_type

	_DEFAULT_AUTOESCAPE = "xhtml_escape"
	_UNSET = object()

	class Template(object):
	"""A compiled template.

	We compile into Python from the given template_string. You can generate
	the template from variables with generate().
	"""
	def __init__(self, template_string, name="<string>", loader=None,
	compress_whitespace=None, autoescape=_UNSET):
	self.name = name
	if compress_whitespace is None:
	compress_whitespace = name.endswith(".html") or \
	name.endswith(".js")
	if autoescape is not _UNSET:
	self.autoescape = autoescape
	elif loader:
	self.autoescape = loader.autoescape
	else:
	self.autoescape = _DEFAULT_AUTOESCAPE
	reader = _TemplateReader(name, escape.native_str(template_string))
	self.file = _File(_parse(reader, self))
	self.code = self._generate_python(loader, compress_whitespace)
	try:
	self.compiled = compile(self.code, "<template %s>" % self.name,
	"exec")
	except:
	formatted_code = _format_code(self.code).rstrip()
	logging.error("%s code:\n%s", self.name, formatted_code)
	raise

	def generate(self, **kwargs):
	"""Generate this template with the given arguments."""
	namespace = {
	"escape": escape.xhtml_escape,
	"xhtml_escape": escape.xhtml_escape,
	"url_escape": escape.url_escape,
	"json_encode": escape.json_encode,
	"squeeze": escape.squeeze,
	"linkify": escape.linkify,
	"datetime": datetime,
	"_utf8": escape.utf8, # for internal use
	"_string_types": (unicode, bytes_type),
	}
	namespace.update(kwargs)
	exec self.compiled in namespace
	execute = namespace["_execute"]
	try:
	return execute()
	except:
	formatted_code = _format_code(self.code).rstrip()
	logging.error("%s code:\n%s", self.name, formatted_code)
	raise

	def _generate_python(self, loader, compress_whitespace):
	buffer = cStringIO.StringIO()
	try:
	# named_blocks maps from names to _NamedBlock objects
	named_blocks = {}
	ancestors = self._get_ancestors(loader)
	ancestors.reverse()
	for ancestor in ancestors:
	ancestor.find_named_blocks(loader, named_blocks)
	self.file.find_named_blocks(loader, named_blocks)
	writer = _CodeWriter(buffer, named_blocks, loader, self,
	compress_whitespace)
	ancestors[0].generate(writer)
	return buffer.getvalue()
	finally:
	buffer.close()

	def _get_ancestors(self, loader):
	ancestors = [self.file]
	for chunk in self.file.body.chunks:
	if isinstance(chunk, _ExtendsBlock):
	if not loader:
	raise ParseError("{% extends %} block found, but no "
	"template loader")
	template = loader.load(chunk.name, self.name)
	ancestors.extend(template._get_ancestors(loader))
	return ancestors


	class BaseLoader(object):
	"""Base class for template loaders."""
	def __init__(self, root_directory, autoescape=_DEFAULT_AUTOESCAPE):
	"""Creates a template loader.

	root_directory may be the empty string if this loader does not
	use the filesystem.

	autoescape must be either None or a string naming a function
	in the template namespace, such as "xhtml_escape".
	"""
	self.root = os.path.abspath(root_directory)
	self.autoescape = autoescape
	self.templates = {}

	def reset(self):
	"""Resets the cache of compiled templates."""
	self.templates = {}

	def resolve_path(self, name, parent_path=None):
	"""Converts a possibly-relative path to absolute (used internally)."""
	if parent_path and not parent_path.startswith("<") and \
	not parent_path.startswith("/") and \
	not name.startswith("/"):
	current_path = os.path.join(self.root, parent_path)
	file_dir = os.path.dirname(os.path.abspath(current_path))
	relative_path = os.path.abspath(os.path.join(file_dir, name))
	if relative_path.startswith(self.root):
	name = relative_path[len(self.root) + 1:]
	return name

	def load(self, name, parent_path=None):
	"""Loads a template."""
	name = self.resolve_path(name, parent_path=parent_path)
	if name not in self.templates:
	self.templates[name] = self._create_template(name)
	return self.templates[name]

	def _create_template(self, name):
	raise NotImplementedError()

	class Loader(BaseLoader):
	"""A template loader that loads from a single root directory.

	You must use a template loader to use template constructs like
	{% extends %} and {% include %}. Loader caches all templates after
	they are loaded the first time.
	"""
	def __init__(self, root_directory, **kwargs):
	super(Loader, self).__init__(root_directory, **kwargs)

	def _create_template(self, name):
	path = os.path.join(self.root, name)
	f = open(path, "r")
	template = Template(f.read(), name=name, loader=self)
	f.close()
	return template


	class DictLoader(BaseLoader):
	"""A template loader that loads from a dictionary."""
	def __init__(self, dict, **kwargs):
	super(DictLoader, self).__init__("", **kwargs)
	self.dict = dict

	def _create_template(self, name):
	return Template(self.dict[name], name=name, loader=self)


	class _Node(object):
	def each_child(self):
	return ()

	def generate(self, writer):
	raise NotImplementedError()

	def find_named_blocks(self, loader, named_blocks):
	for child in self.each_child():
	child.find_named_blocks(loader, named_blocks)


	class _File(_Node):
	def __init__(self, body):
	self.body = body

	def generate(self, writer):
	writer.write_line("def _execute():")
	with writer.indent():
	writer.write_line("_buffer = []")
	self.body.generate(writer)
	writer.write_line("return _utf8('').join(_buffer)")

	def each_child(self):
	return (self.body,)



	class _ChunkList(_Node):
	def __init__(self, chunks):
	self.chunks = chunks

	def generate(self, writer):
	for chunk in self.chunks:
	chunk.generate(writer)

	def each_child(self):
	return self.chunks


	class _NamedBlock(_Node):
	def __init__(self, name, body, template):
	self.name = name
	self.body = body
	self.template = template

	def each_child(self):
	return (self.body,)

	def generate(self, writer):
	block = writer.named_blocks[self.name]
	old = writer.current_template
	writer.current_template = block.template
	block.body.generate(writer)
	writer.current_template = old

	def find_named_blocks(self, loader, named_blocks):
	named_blocks[self.name] = self
	_Node.find_named_blocks(self, loader, named_blocks)


	class _ExtendsBlock(_Node):
	def __init__(self, name):
	self.name = name


	class _IncludeBlock(_Node):
	def __init__(self, name, reader):
	self.name = name
	self.template_name = reader.name

	def find_named_blocks(self, loader, named_blocks):
	included = loader.load(self.name, self.template_name)
	included.file.find_named_blocks(loader, named_blocks)

	def generate(self, writer):
	included = writer.loader.load(self.name, self.template_name)
	old = writer.current_template
	writer.current_template = included
	included.file.body.generate(writer)
	writer.current_template = old


	class _ApplyBlock(_Node):
	def __init__(self, method, body=None):
	self.method = method
	self.body = body

	def each_child(self):
	return (self.body,)

	def generate(self, writer):
	method_name = "apply%d" % writer.apply_counter
	writer.apply_counter += 1
	writer.write_line("def %s():" % method_name)
	with writer.indent():
	writer.write_line("_buffer = []")
	self.body.generate(writer)
	writer.write_line("return _utf8('').join(_buffer)")
	writer.write_line("_buffer.append(%s(%s()))" % (
	self.method, method_name))


	class _ControlBlock(_Node):
	def __init__(self, statement, body=None):
	self.statement = statement
	self.body = body

	def each_child(self):
	return (self.body,)

	def generate(self, writer):
	writer.write_line("%s:" % self.statement)
	with writer.indent():
	self.body.generate(writer)


	class _IntermediateControlBlock(_Node):
	def __init__(self, statement):
	self.statement = statement

	def generate(self, writer):
	writer.write_line("%s:" % self.statement, writer.indent_size() - 1)


	class _Statement(_Node):
	def __init__(self, statement):
	self.statement = statement

	def generate(self, writer):
	writer.write_line(self.statement)


	class _Expression(_Node):
	def __init__(self, expression, raw=False):
	self.expression = expression
	self.raw = raw

	def generate(self, writer):
	writer.write_line("_tmp = %s" % self.expression)
	writer.write_line("if isinstance(_tmp, _string_types):"
	" _tmp = _utf8(_tmp)")
	writer.write_line("else: _tmp = _utf8(str(_tmp))")
	if not self.raw and writer.current_template.autoescape is not None:
	# In python3 functions like xhtml_escape return unicode,
	# so we have to convert to utf8 again.
	writer.write_line("_tmp = _utf8(%s(_tmp))" %
	writer.current_template.autoescape)
	writer.write_line("_buffer.append(_tmp)")

	class _Module(_Expression):
	def __init__(self, expression):
	super(_Module, self).__init__("modules." + expression,
	raw=True)

	class _Text(_Node):
	def __init__(self, value):
	self.value = value

	def generate(self, writer):
	value = self.value

	# Compress lots of white space to a single character. If the whitespace
	# breaks a line, have it continue to break a line, but just with a
	# single \n character
	if writer.compress_whitespace and "<pre>" not in value:
	value = re.sub(r"([\t ]+)", " ", value)
	value = re.sub(r"(\s\n\s)", "\n", value)

	if value:
	writer.write_line('_buffer.append(%r)' % escape.utf8(value))


	class ParseError(Exception):
	"""Raised for template syntax errors."""
	pass


	class _CodeWriter(object):
	def __init__(self, file, named_blocks, loader, current_template,
	compress_whitespace):
	self.file = file
	self.named_blocks = named_blocks
	self.loader = loader
	self.current_template = current_template
	self.compress_whitespace = compress_whitespace
	self.apply_counter = 0
	self._indent = 0

	def indent(self):
	return self

	def indent_size(self):
	return self._indent

	def __enter__(self):
	self._indent += 1
	return self

	def __exit__(self, *args):
	assert self._indent > 0
	self._indent -= 1

	def write_line(self, line, indent=None):
	if indent == None:
	indent = self._indent
	for i in xrange(indent):
	self.file.write(" ")
	print >> self.file, line


	class _TemplateReader(object):
	def __init__(self, name, text):
	self.name = name
	self.text = text
	self.line = 0
	self.pos = 0

	def find(self, needle, start=0, end=None):
	assert start >= 0, start
	pos = self.pos
	start += pos
	if end is None:
	index = self.text.find(needle, start)
	else:
	end += pos
	assert end >= start
	index = self.text.find(needle, start, end)
	if index != -1:
	index -= pos
	return index

	def consume(self, count=None):
	if count is None:
	count = len(self.text) - self.pos
	newpos = self.pos + count
	self.line += self.text.count("\n", self.pos, newpos)
	s = self.text[self.pos:newpos]
	self.pos = newpos
	return s

	def remaining(self):
	return len(self.text) - self.pos

	def __len__(self):
	return self.remaining()

	def __getitem__(self, key):
	if type(key) is slice:
	size = len(self)
	start, stop, step = key.indices(size)
	if start is None: start = self.pos
	else: start += self.pos
	if stop is not None: stop += self.pos
	return self.text[slice(start, stop, step)]
	elif key < 0:
	return self.text[key]
	else:
	return self.text[self.pos + key]

	def __str__(self):
	return self.text[self.pos:]


	def _format_code(code):
	lines = code.splitlines()
	format = "%%%dd %%s\n" % len(repr(len(lines) + 1))
	return "".join([format % (i + 1, line) for (i, line) in enumerate(lines)])


	def _parse(reader, template, in_block=None):
	body = _ChunkList([])
	while True:
	# Find next template directive
	curly = 0
	while True:
	curly = reader.find("{", curly)
	if curly == -1 or curly + 1 == reader.remaining():
	# EOF
	if in_block:
	raise ParseError("Missing {%% end %%} block for %s" %
	in_block)
	body.chunks.append(_Text(reader.consume()))
	return body
	# If the first curly brace is not the start of a special token,
	# start searching from the character after it
	if reader[curly + 1] not in ("{", "%"):
	curly += 1
	continue
	# When there are more than 2 curlies in a row, use the
	# innermost ones. This is useful when generating languages
	# like latex where curlies are also meaningful
	if (curly + 2 < reader.remaining() and
	reader[curly + 1] == '{' and reader[curly + 2] == '{'):
	curly += 1
	continue
	break

	# Append any text before the special token
	if curly > 0:
	body.chunks.append(_Text(reader.consume(curly)))

	start_brace = reader.consume(2)
	line = reader.line

	# Template directives may be escaped as "{{!" or "{%!".
	# In this case output the braces and consume the "!".
	# This is especially useful in conjunction with jquery templates,
	# which also use double braces.
	if reader.remaining() and reader[0] == "!":
	reader.consume(1)
	body.chunks.append(_Text(start_brace))
	continue

	# Expression
	if start_brace == "{{":
	end = reader.find("}}")
	if end == -1 or reader.find("\n", 0, end) != -1:
	raise ParseError("Missing end expression }} on line %d" % line)
	contents = reader.consume(end).strip()
	reader.consume(2)
	if not contents:
	raise ParseError("Empty expression on line %d" % line)
	body.chunks.append(_Expression(contents))
	continue

	# Block
	assert start_brace == "{%", start_brace
	end = reader.find("%}")
	if end == -1 or reader.find("\n", 0, end) != -1:
	raise ParseError("Missing end block %%} on line %d" % line)
	contents = reader.consume(end).strip()
	reader.consume(2)
	if not contents:
	raise ParseError("Empty block tag ({%% %%}) on line %d" % line)

	operator, space, suffix = contents.partition(" ")
	suffix = suffix.strip()

	# Intermediate ("else", "elif", etc) blocks
	intermediate_blocks = {
	"else": set(["if", "for", "while"]),
	"elif": set(["if"]),
	"except": set(["try"]),
	"finally": set(["try"]),
	}
	allowed_parents = intermediate_blocks.get(operator)
	if allowed_parents is not None:
	if not in_block:
	raise ParseError("%s outside %s block" %
	(operator, allowed_parents))
	if in_block not in allowed_parents:
	raise ParseError("%s block cannot be attached to %s block" % (operator, in_block))
	body.chunks.append(_IntermediateControlBlock(contents))
	continue

	# End tag
	elif operator == "end":
	if not in_block:
	raise ParseError("Extra {%% end %%} block on line %d" % line)
	return body

	elif operator in ("extends", "include", "set", "import", "from",
	"comment", "autoescape", "raw", "module"):
	if operator == "comment":
	continue
	if operator == "extends":
	suffix = suffix.strip('"').strip("'")
	if not suffix:
	raise ParseError("extends missing file path on line %d" % line)
	block = _ExtendsBlock(suffix)
	elif operator in ("import", "from"):
	if not suffix:
	raise ParseError("import missing statement on line %d" % line)
	block = _Statement(contents)
	elif operator == "include":
	suffix = suffix.strip('"').strip("'")
	if not suffix:
	raise ParseError("include missing file path on line %d" % line)
	block = _IncludeBlock(suffix, reader)
	elif operator == "set":
	if not suffix:
	raise ParseError("set missing statement on line %d" % line)
	block = _Statement(suffix)
	elif operator == "autoescape":
	fn = suffix.strip()
	if fn == "None": fn = None
	template.autoescape = fn
	continue
	elif operator == "raw":
	block = _Expression(suffix, raw=True)
	elif operator == "module":
	block = _Module(suffix)
	body.chunks.append(block)
	continue

	elif operator in ("apply", "block", "try", "if", "for", "while"):
	# parse inner body recursively
	block_body = _parse(reader, template, operator)
	if operator == "apply":
	if not suffix:
	raise ParseError("apply missing method name on line %d" % line)
	block = _ApplyBlock(suffix, block_body)
	elif operator == "block":
	if not suffix:
	raise ParseError("block missing name on line %d" % line)
	block = _NamedBlock(suffix, block_body, template)
	else:
	block = _ControlBlock(contents, block_body)
	body.chunks.append(block)
	continue

	else:
	raise ParseError("unknown operator: %r" % operator)