"""
This is the Django template system.
How it works:
The Lexer.tokenize() function converts a template string (i.e., a string containing
markup with custom template tags) to tokens, which can be either plain text
(TOKEN_TEXT), variables (TOKEN_VAR) or block statements (TOKEN_BLOCK).
The Parser() class takes a list of tokens in its constructor, and its parse()
method returns a compiled template -- which is, under the hood, a list of
Node objects.
Each Node is responsible for creating some sort of output -- e.g. simple text
(TextNode), variable values in a given context (VariableNode), results of basic
logic (IfNode), results of looping (ForNode), or anything else. The core Node
types are TextNode, VariableNode, IfNode and ForNode, but plugin modules can
define their own custom node types.
Each Node has a render() method, which takes a Context and returns a string of
the rendered node. For example, the render() method of a Variable Node returns
the variable's value as a string. The render() method of an IfNode returns the
rendered output of whatever was inside the loop, recursively.
The Template class is a convenient wrapper that takes care of template
compilation and rendering.
Usage:
The only thing you should ever use directly in this file is the Template class.
Create a compiled template object with a template_string, then call render()
with a context. In the compilation stage, the TemplateSyntaxError exception
will be raised if the template doesn't have proper syntax.
Sample code:
>>> from django import template
>>> s = u'{% if test %}{{ varvalue }}
{% endif %}'
>>> t = template.Template(s)
(t is now a compiled template, and its render() method can be called multiple
times with multiple contexts)
>>> c = template.Context({'test':True, 'varvalue': 'Hello'})
>>> t.render(c)
u'Hello
'
>>> c = template.Context({'test':False, 'varvalue': 'Hello'})
>>> t.render(c)
u''
"""
import re
from inspect import getargspec
from django.conf import settings
from django.template.context import Context, RequestContext, ContextPopException
from django.utils.importlib import import_module
from django.utils.itercompat import is_iterable
from django.utils.functional import curry, Promise
from django.utils.text import smart_split, unescape_string_literal, get_text_list
from django.utils.encoding import smart_unicode, force_unicode, smart_str
from django.utils.translation import ugettext as _
from django.utils.safestring import SafeData, EscapeData, mark_safe, mark_for_escaping
from django.utils.formats import localize
from django.utils.html import escape
__all__ = ('Template', 'Context', 'RequestContext', 'compile_string')
TOKEN_TEXT = 0
TOKEN_VAR = 1
TOKEN_BLOCK = 2
TOKEN_COMMENT = 3
# template syntax constants
FILTER_SEPARATOR = '|'
FILTER_ARGUMENT_SEPARATOR = ':'
VARIABLE_ATTRIBUTE_SEPARATOR = '.'
BLOCK_TAG_START = '{%'
BLOCK_TAG_END = '%}'
VARIABLE_TAG_START = '{{'
VARIABLE_TAG_END = '}}'
COMMENT_TAG_START = '{#'
COMMENT_TAG_END = '#}'
SINGLE_BRACE_START = '{'
SINGLE_BRACE_END = '}'
ALLOWED_VARIABLE_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.'
# what to report as the origin for templates that come from non-loader sources
# (e.g. strings)
UNKNOWN_SOURCE="<unknown source>"
# match a variable or block tag and capture the entire tag, including start/end delimiters
tag_re = re.compile('(%s.*?%s|%s.*?%s|%s.*?%s)' % (re.escape(BLOCK_TAG_START), re.escape(BLOCK_TAG_END),
re.escape(VARIABLE_TAG_START), re.escape(VARIABLE_TAG_END),
re.escape(COMMENT_TAG_START), re.escape(COMMENT_TAG_END)))
# global dictionary of libraries that have been loaded using get_library
libraries = {}
# global list of libraries to load by default for a new parser
builtins = []
# True if TEMPLATE_STRING_IF_INVALID contains a format string (%s). None means
# uninitialised.
invalid_var_format_string = None
class TemplateSyntaxError(Exception):
def __str__(self):
try:
import cStringIO as StringIO
except ImportError:
import StringIO
output = StringIO.StringIO()
output.write(Exception.__str__(self))
# Check if we wrapped an exception and print that too.
if hasattr(self, 'exc_info'):
import traceback
output.write('\n\nOriginal ')
e = self.exc_info
traceback.print_exception(e[0], e[1], e[2], 500, output)
return output.getvalue()
class TemplateDoesNotExist(Exception):
pass
class TemplateEncodingError(Exception):
pass
class VariableDoesNotExist(Exception):
def __init__(self, msg, params=()):
self.msg = msg
self.params = params
def __str__(self):
return unicode(self).encode('utf-8')
def __unicode__(self):
return self.msg % tuple([force_unicode(p, errors='replace') for p in self.params])
class InvalidTemplateLibrary(Exception):
pass
class Origin(object):
def __init__(self, name):
self.name = name
def reload(self):
raise NotImplementedError
def __str__(self):
return self.name
class StringOrigin(Origin):
def __init__(self, source):
super(StringOrigin, self).__init__(UNKNOWN_SOURCE)
self.source = source
def reload(self):
return self.source
class Template(object):
def __init__(self, template_string, origin=None, name=''):
try:
template_string = smart_unicode(template_string)
except UnicodeDecodeError:
raise TemplateEncodingError("Templates can only be constructed from unicode or UTF-8 strings.")
if settings.TEMPLATE_DEBUG and origin is None:
origin = StringOrigin(template_string)
self.nodelist = compile_string(template_string, origin)
self.name = name
def __iter__(self):
for node in self.nodelist:
for subnode in node:
yield subnode
def _render(self, context):
return self.nodelist.render(context)
def render(self, context):
"Display stage -- can be called many times"
context.render_context.push()
try:
return self._render(context)
finally:
context.render_context.pop()
def compile_string(template_string, origin):
"Compiles template_string into NodeList ready for rendering"
if settings.TEMPLATE_DEBUG:
from debug import DebugLexer, DebugParser
lexer_class, parser_class = DebugLexer, DebugParser
else:
lexer_class, parser_class = Lexer, Parser
lexer = lexer_class(template_string, origin)
parser = parser_class(lexer.tokenize())
return parser.parse()
class Token(object):
def __init__(self, token_type, contents):
# token_type must be TOKEN_TEXT, TOKEN_VAR, TOKEN_BLOCK or TOKEN_COMMENT.
self.token_type, self.contents = token_type, contents
def __str__(self):
return '<%s token: "%s...">' % \
({TOKEN_TEXT: 'Text', TOKEN_VAR: 'Var', TOKEN_BLOCK: 'Block', TOKEN_COMMENT: 'Comment'}[self.token_type],
self.contents[:20].replace('\n', ''))
def split_contents(self):
split = []
bits = iter(smart_split(self.contents))
for bit in bits:
# Handle translation-marked template pieces
if bit.startswith('_("') or bit.startswith("_('"):
sentinal = bit[2] + ')'
trans_bit = [bit]
while not bit.endswith(sentinal):
bit = bits.next()
trans_bit.append(bit)
bit = ' '.join(trans_bit)
split.append(bit)
return split
class Lexer(object):
def __init__(self, template_string, origin):
self.template_string = template_string
self.origin = origin
def tokenize(self):
"Return a list of tokens from a given template_string."
in_tag = False
result = []
for bit in tag_re.split(self.template_string):
if bit:
result.append(self.create_token(bit, in_tag))
in_tag = not in_tag
return result
def create_token(self, token_string, in_tag):
"""
Convert the given token string into a new Token object and return it.
If in_tag is True, we are processing something that matched a tag,
otherwise it should be treated as a literal string.
"""
if in_tag:
if token_string.startswith(VARIABLE_TAG_START):
token = Token(TOKEN_VAR, token_string[len(VARIABLE_TAG_START):-len(VARIABLE_TAG_END)].strip())
elif token_string.startswith(BLOCK_TAG_START):
token = Token(TOKEN_BLOCK, token_string[len(BLOCK_TAG_START):-len(BLOCK_TAG_END)].strip())
elif token_string.startswith(COMMENT_TAG_START):
token = Token(TOKEN_COMMENT, '')
else:
token = Token(TOKEN_TEXT, token_string)
return token
class Parser(object):
def __init__(self, tokens):
self.tokens = tokens
self.tags = {}
self.filters = {}
for lib in builtins:
self.add_library(lib)
def parse(self, parse_until=None):
if parse_until is None: parse_until = []
nodelist = self.create_nodelist()
while self.tokens:
token = self.next_token()
if token.token_type == TOKEN_TEXT:
self.extend_nodelist(nodelist, TextNode(token.contents), token)
elif token.token_type == TOKEN_VAR:
if not token.contents:
self.empty_variable(token)
filter_expression = self.compile_filter(token.contents)
var_node = self.create_variable_node(filter_expression)
self.extend_nodelist(nodelist, var_node,token)
elif token.token_type == TOKEN_BLOCK:
if token.contents in parse_until:
# put token back on token list so calling code knows why it terminated
self.prepend_token(token)
return nodelist
try:
command = token.contents.split()[0]
except IndexError:
self.empty_block_tag(token)
# execute callback function for this tag and append resulting node
self.enter_command(command, token)
try:
compile_func = self.tags[command]
except KeyError:
self.invalid_block_tag(token, command, parse_until)
try:
compiled_result = compile_func(self, token)
except TemplateSyntaxError, e:
if not self.compile_function_error(token, e):
raise
self.extend_nodelist(nodelist, compiled_result, token)
self.exit_command()
if parse_until:
self.unclosed_block_tag(parse_until)
return nodelist
def skip_past(self, endtag):
while self.tokens:
token = self.next_token()
if token.token_type == TOKEN_BLOCK and token.contents == endtag:
return
self.unclosed_block_tag([endtag])
def create_variable_node(self, filter_expression):
return VariableNode(filter_expression)
def create_nodelist(self):
return NodeList()
def extend_nodelist(self, nodelist, node, token):
if node.must_be_first and nodelist:
try:
if nodelist.contains_nontext:
raise AttributeError
except AttributeError:
raise TemplateSyntaxError("%r must be the first tag in the template." % node)
if isinstance(nodelist, NodeList) and not isinstance(node, TextNode):
nodelist.contains_nontext = True
nodelist.append(node)
def enter_command(self, command, token):
pass
def exit_command(self):
pass
def error(self, token, msg):
return TemplateSyntaxError(msg)
def empty_variable(self, token):
raise self.error(token, "Empty variable tag")
def empty_block_tag(self, token):
raise self.error(token, "Empty block tag")
def invalid_block_tag(self, token, command, parse_until=None):
if parse_until:
raise self.error(token, "Invalid block tag: '%s', expected %s" % (command, get_text_list(["'%s'" % p for p in parse_until])))
raise self.error(token, "Invalid block tag: '%s'" % command)
def unclosed_block_tag(self, parse_until):
raise self.error(None, "Unclosed tags: %s " % ', '.join(parse_until))
def compile_function_error(self, token, e):
pass
def next_token(self):
return self.tokens.pop(0)
def prepend_token(self, token):
self.tokens.insert(0, token)
def delete_first_token(self):
del self.tokens[0]
def add_library(self, lib):
self.tags.update(lib.tags)
self.filters.update(lib.filters)
def compile_filter(self, token):
"Convenient wrapper for FilterExpression"
return FilterExpression(token, self)
def find_filter(self, filter_name):
if filter_name in self.filters:
return self.filters[filter_name]
else:
raise TemplateSyntaxError("Invalid filter: '%s'" % filter_name)
class TokenParser(object):
"""
Subclass this and implement the top() method to parse a template line. When
instantiating the parser, pass in the line from the Django template parser.
The parser's "tagname" instance-variable stores the name of the tag that
the filter was called with.
"""
def __init__(self, subject):
self.subject = subject
self.pointer = 0
self.backout = []
self.tagname = self.tag()
def top(self):
"Overload this method to do the actual parsing and return the result."
raise NotImplementedError()
def more(self):
"Returns True if there is more stuff in the tag."
return self.pointer < len(self.subject)
def back(self):
"Undoes the last microparser. Use this for lookahead and backtracking."
if not len(self.backout):
raise TemplateSyntaxError("back called without some previous parsing")
self.pointer = self.backout.pop()
def tag(self):
"A microparser that just returns the next tag from the line."
subject = self.subject
i = self.pointer
if i >= len(subject):
raise TemplateSyntaxError("expected another tag, found end of string: %s" % subject)
p = i
while i < len(subject) and subject[i] not in (' ', '\t'):
i += 1
s = subject[p:i]
while i < len(subject) and subject[i] in (' ', '\t'):
i += 1
self.backout.append(self.pointer)
self.pointer = i
return s
def value(self):
"A microparser that parses for a value: some string constant or variable name."
subject = self.subject
i = self.pointer
def next_space_index(subject, i):
"Increment pointer until a real space (i.e. a space not within quotes) is encountered"
while i < len(subject) and subject[i] not in (' ', '\t'):
if subject[i] in ('"', "'"):
c = subject[i]
i += 1
while i < len(subject) and subject[i] != c:
i += 1
if i >= len(subject):
raise TemplateSyntaxError("Searching for value. Unexpected end of string in column %d: %s" % (i, subject))
i += 1
return i
if i >= len(subject):
raise TemplateSyntaxError("Searching for value. Expected another value but found end of string: %s" % subject)
if subject[i] in ('"', "'"):
p = i
i += 1
while i < len(subject) and subject[i] != subject[p]:
i += 1
if i >= len(subject):
raise TemplateSyntaxError("Searching for value. Unexpected end of string in column %d: %s" % (i, subject))
i += 1
# Continue parsing until next "real" space, so that filters are also included
i = next_space_index(subject, i)
res = subject[p:i]
while i < len(subject) and subject[i] in (' ', '\t'):
i += 1
self.backout.append(self.pointer)
self.pointer = i
return res
else:
p = i
i = next_space_index(subject, i)
s = subject[p:i]
while i < len(subject) and subject[i] in (' ', '\t'):
i += 1
self.backout.append(self.pointer)
self.pointer = i
return s
# This only matches constant *strings* (things in quotes or marked for
# translation). Numbers are treated as variables for implementation reasons
# (so that they retain their type when passed to filters).
constant_string = r"""
(?:%(i18n_open)s%(strdq)s%(i18n_close)s|
%(i18n_open)s%(strsq)s%(i18n_close)s|
%(strdq)s|
%(strsq)s)
""" % {
'strdq': r'"[^"\\]*(?:\\.[^"\\]*)*"', # double-quoted string
'strsq': r"'[^'\\]*(?:\\.[^'\\]*)*'", # single-quoted string
'i18n_open' : re.escape("_("),
'i18n_close' : re.escape(")"),
}
constant_string = constant_string.replace("\n", "")
filter_raw_string = r"""
^(?P%(constant)s)|
^(?P[%(var_chars)s]+|%(num)s)|
(?:%(filter_sep)s
(?P\w+)
(?:%(arg_sep)s
(?:
(?P%(constant)s)|
(?P[%(var_chars)s]+|%(num)s)
)
)?
)""" % {
'constant': constant_string,
'num': r'[-+\.]?\d[\d\.e]*',
'var_chars': "\w\." ,
'filter_sep': re.escape(FILTER_SEPARATOR),
'arg_sep': re.escape(FILTER_ARGUMENT_SEPARATOR),
}
filter_re = re.compile(filter_raw_string, re.UNICODE|re.VERBOSE)
class FilterExpression(object):
r"""
Parses a variable token and its optional filters (all as a single string),
and return a list of tuples of the filter name and arguments.
Sample:
>>> token = 'variable|default:"Default value"|date:"Y-m-d"'
>>> p = Parser('')
>>> fe = FilterExpression(token, p)
>>> len(fe.filters)
2
>>> fe.var
This class should never be instantiated outside of the
get_filters_from_token helper function.
"""
def __init__(self, token, parser):
self.token = token
matches = filter_re.finditer(token)
var_obj = None
filters = []
upto = 0
for match in matches:
start = match.start()
if upto != start:
raise TemplateSyntaxError("Could not parse some characters: %s|%s|%s" % \
(token[:upto], token[upto:start], token[start:]))
if var_obj is None:
var, constant = match.group("var", "constant")
if constant:
try:
var_obj = Variable(constant).resolve({})
except VariableDoesNotExist:
var_obj = None
elif var is None:
raise TemplateSyntaxError("Could not find variable at start of %s." % token)
else:
var_obj = Variable(var)
else:
filter_name = match.group("filter_name")
args = []
constant_arg, var_arg = match.group("constant_arg", "var_arg")
if constant_arg:
args.append((False, Variable(constant_arg).resolve({})))
elif var_arg:
args.append((True, Variable(var_arg)))
filter_func = parser.find_filter(filter_name)
self.args_check(filter_name, filter_func, args)
filters.append((filter_func, args))
upto = match.end()
if upto != len(token):
raise TemplateSyntaxError("Could not parse the remainder: '%s' from '%s'" % (token[upto:], token))
self.filters = filters
self.var = var_obj
def resolve(self, context, ignore_failures=False):
if isinstance(self.var, Variable):
try:
obj = self.var.resolve(context)
except VariableDoesNotExist:
if ignore_failures:
obj = None
else:
if settings.TEMPLATE_STRING_IF_INVALID:
global invalid_var_format_string
if invalid_var_format_string is None:
invalid_var_format_string = '%s' in settings.TEMPLATE_STRING_IF_INVALID
if invalid_var_format_string:
return settings.TEMPLATE_STRING_IF_INVALID % self.var
return settings.TEMPLATE_STRING_IF_INVALID
else:
obj = settings.TEMPLATE_STRING_IF_INVALID
else:
obj = self.var
for func, args in self.filters:
arg_vals = []
for lookup, arg in args:
if not lookup:
arg_vals.append(mark_safe(arg))
else:
arg_vals.append(arg.resolve(context))
if getattr(func, 'needs_autoescape', False):
new_obj = func(obj, autoescape=context.autoescape, *arg_vals)
else:
new_obj = func(obj, *arg_vals)
if getattr(func, 'is_safe', False) and isinstance(obj, SafeData):
obj = mark_safe(new_obj)
elif isinstance(obj, EscapeData):
obj = mark_for_escaping(new_obj)
else:
obj = new_obj
return obj
def args_check(name, func, provided):
provided = list(provided)
plen = len(provided)
# Check to see if a decorator is providing the real function.
func = getattr(func, '_decorated_function', func)
args, varargs, varkw, defaults = getargspec(func)
# First argument is filter input.
args.pop(0)
if defaults:
nondefs = args[:-len(defaults)]
else:
nondefs = args
# Args without defaults must be provided.
try:
for arg in nondefs:
provided.pop(0)
except IndexError:
# Not enough
raise TemplateSyntaxError("%s requires %d arguments, %d provided" % (name, len(nondefs), plen))
# Defaults can be overridden.
defaults = defaults and list(defaults) or []
try:
for parg in provided:
defaults.pop(0)
except IndexError:
# Too many.
raise TemplateSyntaxError("%s requires %d arguments, %d provided" % (name, len(nondefs), plen))
return True
args_check = staticmethod(args_check)
def __str__(self):
return self.token
def resolve_variable(path, context):
"""
Returns the resolved variable, which may contain attribute syntax, within
the given context.
Deprecated; use the Variable class instead.
"""
return Variable(path).resolve(context)
class Variable(object):
r"""
A template variable, resolvable against a given context. The variable may be
a hard-coded string (if it begins and ends with single or double quote
marks)::
>>> c = {'article': {'section':u'News'}}
>>> Variable('article.section').resolve(c)
u'News'
>>> Variable('article').resolve(c)
{'section': u'News'}
>>> class AClass: pass
>>> c = AClass()
>>> c.article = AClass()
>>> c.article.section = u'News'
(The example assumes VARIABLE_ATTRIBUTE_SEPARATOR is '.')
"""
def __init__(self, var):
self.var = var
self.literal = None
self.lookups = None
self.translate = False
try:
# First try to treat this variable as a number.
#
# Note that this could cause an OverflowError here that we're not
# catching. Since this should only happen at compile time, that's
# probably OK.
self.literal = float(var)
# So it's a float... is it an int? If the original value contained a
# dot or an "e" then it was a float, not an int.
if '.' not in var and 'e' not in var.lower():
self.literal = int(self.literal)
# "2." is invalid
if var.endswith('.'):
raise ValueError
except ValueError:
# A ValueError means that the variable isn't a number.
if var.startswith('_(') and var.endswith(')'):
# The result of the lookup should be translated at rendering
# time.
self.translate = True
var = var[2:-1]
# If it's wrapped with quotes (single or double), then
# we're also dealing with a literal.
try:
self.literal = mark_safe(unescape_string_literal(var))
except ValueError:
# Otherwise we'll set self.lookups so that resolve() knows we're
# dealing with a bonafide variable
if var.find(VARIABLE_ATTRIBUTE_SEPARATOR + '_') > -1 or var[0] == '_':
raise TemplateSyntaxError("Variables and attributes may not begin with underscores: '%s'" % var)
self.lookups = tuple(var.split(VARIABLE_ATTRIBUTE_SEPARATOR))
def resolve(self, context):
"""Resolve this variable against a given context."""
if self.lookups is not None:
# We're dealing with a variable that needs to be resolved
value = self._resolve_lookup(context)
else:
# We're dealing with a literal, so it's already been "resolved"
value = self.literal
if self.translate:
return _(value)
return value
def __repr__(self):
return "<%s: %r>" % (self.__class__.__name__, self.var)
def __str__(self):
return self.var
def _resolve_lookup(self, context):
"""
Performs resolution of a real variable (i.e. not a literal) against the
given context.
As indicated by the method's name, this method is an implementation
detail and shouldn't be called by external code. Use Variable.resolve()
instead.
"""
current = context
for bit in self.lookups:
try: # dictionary lookup
current = current[bit]
except (TypeError, AttributeError, KeyError):
try: # attribute lookup
current = getattr(current, bit)
if callable(current):
if getattr(current, 'alters_data', False):
current = settings.TEMPLATE_STRING_IF_INVALID
else:
try: # method call (assuming no args required)
current = current()
except TypeError: # arguments *were* required
# GOTCHA: This will also catch any TypeError
# raised in the function itself.
current = settings.TEMPLATE_STRING_IF_INVALID # invalid method call
except Exception, e:
if getattr(e, 'silent_variable_failure', False):
current = settings.TEMPLATE_STRING_IF_INVALID
else:
raise
except (TypeError, AttributeError):
try: # list-index lookup
current = current[int(bit)]
except (IndexError, # list index out of range
ValueError, # invalid literal for int()
KeyError, # current is a dict without `int(bit)` key
TypeError, # unsubscriptable object
):
raise VariableDoesNotExist("Failed lookup for key [%s] in %r", (bit, current)) # missing attribute
except Exception, e:
if getattr(e, 'silent_variable_failure', False):
current = settings.TEMPLATE_STRING_IF_INVALID
else:
raise
return current
class Node(object):
# Set this to True for nodes that must be first in the template (although
# they can be preceded by text nodes.
must_be_first = False
def render(self, context):
"Return the node rendered as a string"
pass
def __iter__(self):
yield self
def get_nodes_by_type(self, nodetype):
"Return a list of all nodes (within this node and its nodelist) of the given type"
nodes = []
if isinstance(self, nodetype):
nodes.append(self)
if hasattr(self, 'nodelist'):
nodes.extend(self.nodelist.get_nodes_by_type(nodetype))
return nodes
class NodeList(list):
# Set to True the first time a non-TextNode is inserted by
# extend_nodelist().
contains_nontext = False
def render(self, context):
bits = []
for node in self:
if isinstance(node, Node):
bits.append(self.render_node(node, context))
else:
bits.append(node)
return mark_safe(''.join([force_unicode(b) for b in bits]))
def get_nodes_by_type(self, nodetype):
"Return a list of all nodes of the given type"
nodes = []
for node in self:
nodes.extend(node.get_nodes_by_type(nodetype))
return nodes
def render_node(self, node, context):
return node.render(context)
class TextNode(Node):
def __init__(self, s):
self.s = s
def __repr__(self):
return "" % smart_str(self.s[:25], 'ascii',
errors='replace')
def render(self, context):
return self.s
def _render_value_in_context(value, context):
"""
Converts any value to a string to become part of a rendered template. This
means escaping, if required, and conversion to a unicode object. If value
is a string, it is expected to have already been translated.
"""
value = localize(value)
value = force_unicode(value)
if (context.autoescape and not isinstance(value, SafeData)) or isinstance(value, EscapeData):
return escape(value)
else:
return value
class VariableNode(Node):
def __init__(self, filter_expression):
self.filter_expression = filter_expression
def __repr__(self):
return "" % self.filter_expression
def render(self, context):
try:
output = self.filter_expression.resolve(context)
except UnicodeDecodeError:
# Unicode conversion can fail sometimes for reasons out of our
# control (e.g. exception rendering). In that case, we fail quietly.
return ''
return _render_value_in_context(output, context)
def generic_tag_compiler(params, defaults, name, node_class, parser, token):
"Returns a template.Node subclass."
bits = token.split_contents()[1:]
bmax = len(params)
def_len = defaults and len(defaults) or 0
bmin = bmax - def_len
if(len(bits) < bmin or len(bits) > bmax):
if bmin == bmax:
message = "%s takes %s arguments" % (name, bmin)
else:
message = "%s takes between %s and %s arguments" % (name, bmin, bmax)
raise TemplateSyntaxError(message)
return node_class(bits)
class Library(object):
def __init__(self):
self.filters = {}
self.tags = {}
def tag(self, name=None, compile_function=None):
if name == None and compile_function == None:
# @register.tag()
return self.tag_function
elif name != None and compile_function == None:
if(callable(name)):
# @register.tag
return self.tag_function(name)
else:
# @register.tag('somename') or @register.tag(name='somename')
def dec(func):
return self.tag(name, func)
return dec
elif name != None and compile_function != None:
# register.tag('somename', somefunc)
self.tags[name] = compile_function
return compile_function
else:
raise InvalidTemplateLibrary("Unsupported arguments to Library.tag: (%r, %r)", (name, compile_function))
def tag_function(self,func):
self.tags[getattr(func, "_decorated_function", func).__name__] = func
return func
def filter(self, name=None, filter_func=None):
if name == None and filter_func == None:
# @register.filter()
return self.filter_function
elif filter_func == None:
if(callable(name)):
# @register.filter
return self.filter_function(name)
else:
# @register.filter('somename') or @register.filter(name='somename')
def dec(func):
return self.filter(name, func)
return dec
elif name != None and filter_func != None:
# register.filter('somename', somefunc)
self.filters[name] = filter_func
return filter_func
else:
raise InvalidTemplateLibrary("Unsupported arguments to Library.filter: (%r, %r)", (name, filter_func))
def filter_function(self, func):
self.filters[getattr(func, "_decorated_function", func).__name__] = func
return func
def simple_tag(self,func):
params, xx, xxx, defaults = getargspec(func)
class SimpleNode(Node):
def __init__(self, vars_to_resolve):
self.vars_to_resolve = map(Variable, vars_to_resolve)
def render(self, context):
resolved_vars = [var.resolve(context) for var in self.vars_to_resolve]
return func(*resolved_vars)
compile_func = curry(generic_tag_compiler, params, defaults, getattr(func, "_decorated_function", func).__name__, SimpleNode)
compile_func.__doc__ = func.__doc__
self.tag(getattr(func, "_decorated_function", func).__name__, compile_func)
return func
def inclusion_tag(self, file_name, context_class=Context, takes_context=False):
def dec(func):
params, xx, xxx, defaults = getargspec(func)
if takes_context:
if params[0] == 'context':
params = params[1:]
else:
raise TemplateSyntaxError("Any tag function decorated with takes_context=True must have a first argument of 'context'")
class InclusionNode(Node):
def __init__(self, vars_to_resolve):
self.vars_to_resolve = map(Variable, vars_to_resolve)
def render(self, context):
resolved_vars = [var.resolve(context) for var in self.vars_to_resolve]
if takes_context:
args = [context] + resolved_vars
else:
args = resolved_vars
dict = func(*args)
if not getattr(self, 'nodelist', False):
from django.template.loader import get_template, select_template
if not isinstance(file_name, basestring) and is_iterable(file_name):
t = select_template(file_name)
else:
t = get_template(file_name)
self.nodelist = t.nodelist
new_context = context_class(dict, autoescape=context.autoescape)
# Copy across the CSRF token, if present, because inclusion
# tags are often used for forms, and we need instructions
# for using CSRF protection to be as simple as possible.
csrf_token = context.get('csrf_token', None)
if csrf_token is not None:
new_context['csrf_token'] = csrf_token
return self.nodelist.render(new_context)
compile_func = curry(generic_tag_compiler, params, defaults, getattr(func, "_decorated_function", func).__name__, InclusionNode)
compile_func.__doc__ = func.__doc__
self.tag(getattr(func, "_decorated_function", func).__name__, compile_func)
return func
return dec
def import_library(taglib_module):
"""Load a template tag library module.
Verifies that the library contains a 'register' attribute, and
returns that attribute as the representation of the library
"""
try:
mod = import_module(taglib_module)
except ImportError:
return None
try:
return mod.register
except AttributeError:
raise InvalidTemplateLibrary("Template library %s does not have a variable named 'register'" % taglib_module)
templatetags_modules = []
def get_templatetags_modules():
"""Return the list of all available template tag modules.
Caches the result for faster access.
"""
global templatetags_modules
if not templatetags_modules:
_templatetags_modules = []
# Populate list once per thread.
for app_module in ['django'] + list(settings.INSTALLED_APPS):
try:
templatetag_module = '%s.templatetags' % app_module
import_module(templatetag_module)
_templatetags_modules.append(templatetag_module)
except ImportError:
continue
templatetags_modules = _templatetags_modules
return templatetags_modules
def get_library(library_name):
"""
Load the template library module with the given name.
If library is not already loaded loop over all templatetags modules to locate it.
{% load somelib %} and {% load someotherlib %} loops twice.
Subsequent loads eg. {% load somelib %} in the same process will grab the cached
module from libraries.
"""
lib = libraries.get(library_name, None)
if not lib:
templatetags_modules = get_templatetags_modules()
tried_modules = []
for module in templatetags_modules:
taglib_module = '%s.%s' % (module, library_name)
tried_modules.append(taglib_module)
lib = import_library(taglib_module)
if lib:
libraries[library_name] = lib
break
if not lib:
raise InvalidTemplateLibrary("Template library %s not found, tried %s" % (library_name, ','.join(tried_modules)))
return lib
def add_to_builtins(module):
builtins.append(import_library(module))
add_to_builtins('django.template.defaulttags')
add_to_builtins('django.template.defaultfilters')