• Language: en

Source code for django.template.base

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 a ForNode 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.


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 = '<html>{% if test %}<h1>{{ varvalue }}</h1>{% endif %}</html>'
>>> 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)
>>> c = template.Context({'test':False, 'varvalue': 'Hello'})
>>> t.render(c)

import inspect
import logging
import re

from django.template.context import (  # NOQA: imported for backwards compatibility
    BaseContext, Context, ContextPopException, RequestContext,
from django.utils.formats import localize
from django.utils.html import conditional_escape, escape
from django.utils.inspect import getargspec
from django.utils.safestring import SafeData, mark_safe
from django.utils.text import (
    get_text_list, smart_split, unescape_string_literal,
from django.utils.timezone import template_localtime
from django.utils.translation import gettext_lazy, pgettext_lazy

from .exceptions import TemplateSyntaxError

    TOKEN_TEXT: 'Text',
    TOKEN_VAR: 'Var',
    TOKEN_BLOCK: 'Block',
    TOKEN_COMMENT: 'Comment',

# template syntax constants

# 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))))

logger = logging.getLogger('django.template')

class VariableDoesNotExist(Exception):

    def __init__(self, msg, params=()):
        self.msg = msg
        self.params = params

    def __str__(self):
        return self.msg % self.params

[docs]class Origin: def __init__(self, name, template_name=None, loader=None): self.name = name self.template_name = template_name self.loader = loader def __str__(self): return self.name def __eq__(self, other): if not isinstance(other, Origin): return False return ( self.name == other.name and self.loader == other.loader ) @property def loader_name(self): if self.loader: return '%s.%s' % ( self.loader.__module__, self.loader.__class__.__name__, )
[docs]class Template: def __init__(self, template_string, origin=None, name=None, engine=None): # If Template is instantiated directly rather than from an Engine and # exactly one Django template engine is configured, use that engine. # This is required to preserve backwards-compatibility for direct use # e.g. Template('...').render(Context({...})) if engine is None: from .engine import Engine engine = Engine.get_default() if origin is None: origin = Origin(UNKNOWN_SOURCE) self.name = name self.origin = origin self.engine = engine self.source = template_string self.nodelist = self.compile_nodelist() def __iter__(self): for node in self.nodelist: yield from node def _render(self, context): return self.nodelist.render(context)
[docs] def render(self, context): "Display stage -- can be called many times" with context.render_context.push_state(self): if context.template is None: with context.bind_template(self): context.template_name = self.name return self._render(context) else: return self._render(context)
def compile_nodelist(self): """ Parse and compile the template source into a nodelist. If debug is True and an exception occurs during parsing, the exception is is annotated with contextual line information where it occurred in the template source. """ if self.engine.debug: lexer = DebugLexer(self.source) else: lexer = Lexer(self.source) tokens = lexer.tokenize() parser = Parser( tokens, self.engine.template_libraries, self.engine.template_builtins, self.origin, ) try: return parser.parse() except Exception as e: if self.engine.debug: e.template_debug = self.get_exception_info(e, e.token) raise def get_exception_info(self, exception, token): """ Return a dictionary containing contextual line information of where the exception occurred in the template. The following information is provided: message The message of the exception raised. source_lines The lines before, after, and including the line the exception occurred on. line The line number the exception occurred on. before, during, after The line the exception occurred on split into three parts: 1. The content before the token that raised the error. 2. The token that raised the error. 3. The content after the token that raised the error. total The number of lines in source_lines. top The line number where source_lines starts. bottom The line number where source_lines ends. start The start position of the token in the template source. end The end position of the token in the template source. """ start, end = token.position context_lines = 10 line = 0 upto = 0 source_lines = [] before = during = after = "" for num, next in enumerate(linebreak_iter(self.source)): if start >= upto and end <= next: line = num before = escape(self.source[upto:start]) during = escape(self.source[start:end]) after = escape(self.source[end:next]) source_lines.append((num, escape(self.source[upto:next]))) upto = next total = len(source_lines) top = max(1, line - context_lines) bottom = min(total, line + 1 + context_lines) # In some rare cases exc_value.args can be empty or an invalid # string. try: message = str(exception.args[0]) except (IndexError, UnicodeDecodeError): message = '(Could not get exception message)' return { 'message': message, 'source_lines': source_lines[top:bottom], 'before': before, 'during': during, 'after': after, 'top': top, 'bottom': bottom, 'total': total, 'line': line, 'name': self.origin.name, 'start': start, 'end': end, }
def linebreak_iter(template_source): yield 0 p = template_source.find('\n') while p >= 0: yield p + 1 p = template_source.find('\n', p + 1) yield len(template_source) + 1 class Token: def __init__(self, token_type, contents, position=None, lineno=None): """ A token representing a string from the template. token_type One of TOKEN_TEXT, TOKEN_VAR, TOKEN_BLOCK, or TOKEN_COMMENT. contents The token source string. position An optional tuple containing the start and end index of the token in the template source. This is used for traceback information when debug is on. lineno The line number the token appears on in the template source. This is used for traceback information and gettext files. """ self.token_type, self.contents = token_type, contents self.lineno = lineno self.position = position def __str__(self): token_name = TOKEN_MAPPING[self.token_type] return ('<%s token: "%s...">' % (token_name, 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(('_("', "_('")): sentinel = bit[2] + ')' trans_bit = [bit] while not bit.endswith(sentinel): bit = next(bits) trans_bit.append(bit) bit = ' '.join(trans_bit) split.append(bit) return split class Lexer: def __init__(self, template_string): self.template_string = template_string self.verbatim = False def tokenize(self): """ Return a list of tokens from a given template_string. """ in_tag = False lineno = 1 result = [] for bit in tag_re.split(self.template_string): if bit: result.append(self.create_token(bit, None, lineno, in_tag)) in_tag = not in_tag lineno += bit.count('\n') return result def create_token(self, token_string, position, lineno, 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 and token_string.startswith(BLOCK_TAG_START): # The [2:-2] ranges below strip off *_TAG_START and *_TAG_END. # We could do len(BLOCK_TAG_START) to be more "correct", but we've # hard-coded the 2s here for performance. And it's not like # the TAG_START values are going to change anytime, anyway. block_content = token_string[2:-2].strip() if self.verbatim and block_content == self.verbatim: self.verbatim = False if in_tag and not self.verbatim: if token_string.startswith(VARIABLE_TAG_START): token = Token(TOKEN_VAR, token_string[2:-2].strip(), position, lineno) elif token_string.startswith(BLOCK_TAG_START): if block_content[:9] in ('verbatim', 'verbatim '): self.verbatim = 'end%s' % block_content token = Token(TOKEN_BLOCK, block_content, position, lineno) elif token_string.startswith(COMMENT_TAG_START): content = '' if token_string.find(TRANSLATOR_COMMENT_MARK): content = token_string[2:-2].strip() token = Token(TOKEN_COMMENT, content, position, lineno) else: token = Token(TOKEN_TEXT, token_string, position, lineno) return token class DebugLexer(Lexer): def tokenize(self): """ Split a template string into tokens and annotates each token with its start and end position in the source. This is slower than the default lexer so only use it when debug is True. """ lineno = 1 result = [] upto = 0 for match in tag_re.finditer(self.template_string): start, end = match.span() if start > upto: token_string = self.template_string[upto:start] result.append(self.create_token(token_string, (upto, start), lineno, in_tag=False)) lineno += token_string.count('\n') upto = start token_string = self.template_string[start:end] result.append(self.create_token(token_string, (start, end), lineno, in_tag=True)) lineno += token_string.count('\n') upto = end last_bit = self.template_string[upto:] if last_bit: result.append(self.create_token(last_bit, (upto, upto + len(last_bit)), lineno, in_tag=False)) return result class Parser: def __init__(self, tokens, libraries=None, builtins=None, origin=None): self.tokens = tokens self.tags = {} self.filters = {} self.command_stack = [] if libraries is None: libraries = {} if builtins is None: builtins = [] self.libraries = libraries for builtin in builtins: self.add_library(builtin) self.origin = origin def parse(self, parse_until=None): """ Iterate through the parser tokens and compiles each one into a node. If parse_until is provided, parsing will stop once one of the specified tokens has been reached. This is formatted as a list of tokens, e.g. ['elif', 'else', 'endif']. If no matching token is reached, raise an exception with the unclosed block tag details. """ if parse_until is None: parse_until = [] nodelist = NodeList() while self.tokens: token = self.next_token() # Use the raw values here for TOKEN_* for a tiny performance boost. if token.token_type == 0: # TOKEN_TEXT self.extend_nodelist(nodelist, TextNode(token.contents), token) elif token.token_type == 1: # TOKEN_VAR if not token.contents: raise self.error(token, 'Empty variable tag on line %d' % token.lineno) try: filter_expression = self.compile_filter(token.contents) except TemplateSyntaxError as e: raise self.error(token, e) var_node = VariableNode(filter_expression) self.extend_nodelist(nodelist, var_node, token) elif token.token_type == 2: # TOKEN_BLOCK try: command = token.contents.split()[0] except IndexError: raise self.error(token, 'Empty block tag on line %d' % token.lineno) if command in parse_until: # A matching token has been reached. Return control to # the caller. Put the token back on the token list so the # caller knows where it terminated. self.prepend_token(token) return nodelist # Add the token to the command stack. This is used for error # messages if further parsing fails due to an unclosed block # tag. self.command_stack.append((command, token)) # Get the tag callback function from the ones registered with # the parser. try: compile_func = self.tags[command] except KeyError: self.invalid_block_tag(token, command, parse_until) # Compile the callback into a node object and add it to # the node list. try: compiled_result = compile_func(self, token) except Exception as e: raise self.error(token, e) self.extend_nodelist(nodelist, compiled_result, token) # Compile success. Remove the token from the command stack. self.command_stack.pop() 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 extend_nodelist(self, nodelist, node, token): # Check that non-text nodes don't appear before an extends tag. if node.must_be_first and nodelist.contains_nontext: raise self.error( token, '%r must be the first tag in the template.' % node, ) if isinstance(nodelist, NodeList) and not isinstance(node, TextNode): nodelist.contains_nontext = True # Set origin and token here since we can't modify the node __init__() # method. node.token = token node.origin = self.origin nodelist.append(node) def error(self, token, e): """ Return an exception annotated with the originating token. Since the parser can be called recursively, check if a token is already set. This ensures the innermost token is highlighted if an exception occurs, e.g. a compile error within the body of an if statement. """ if not isinstance(e, Exception): e = TemplateSyntaxError(e) if not hasattr(e, 'token'): e.token = token return e def invalid_block_tag(self, token, command, parse_until=None): if parse_until: raise self.error( token, "Invalid block tag on line %d: '%s', expected %s. Did you " "forget to register or load this tag?" % ( token.lineno, command, get_text_list(["'%s'" % p for p in parse_until], 'or'), ), ) raise self.error( token, "Invalid block tag on line %d: '%s'. Did you forget to register " "or load this tag?" % (token.lineno, command) ) def unclosed_block_tag(self, parse_until): command, token = self.command_stack.pop() msg = "Unclosed tag on line %d: '%s'. Looking for one of: %s." % ( token.lineno, command, ', '.join(parse_until), ) raise self.error(token, msg) 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) # 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>%(constant)s)| ^(?P<var>[%(var_chars)s]+|%(num)s)| (?:\s*%(filter_sep)s\s* (?P<filter_name>\w+) (?:%(arg_sep)s (?: (?P<constant_arg>%(constant)s)| (?P<var_arg>[%(var_chars)s]+|%(num)s) ) )? )""" % { 'constant': constant_string, 'num': r'[-+\.]?\d[\d\.e]*', 'var_chars': r'\w\.', 'filter_sep': re.escape(FILTER_SEPARATOR), 'arg_sep': re.escape(FILTER_ARGUMENT_SEPARATOR), } filter_re = re.compile(filter_raw_string, re.VERBOSE) class FilterExpression: """ Parse 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 <Variable: 'variable'> """ 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: string_if_invalid = context.template.engine.string_if_invalid if string_if_invalid: if '%s' in string_if_invalid: return string_if_invalid % self.var else: return string_if_invalid else: obj = 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, 'expects_localtime', False): obj = template_localtime(obj, context.use_tz) 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) else: obj = new_obj return obj def args_check(name, func, provided): provided = list(provided) # First argument, filter input, is implied. plen = len(provided) + 1 # Check to see if a decorator is providing the real function. func = getattr(func, '_decorated_function', func) args, _, _, defaults = getargspec(func) alen = len(args) dlen = len(defaults or []) # Not enough OR Too many if plen < (alen - dlen) or plen > alen: raise TemplateSyntaxError("%s requires %d arguments, %d provided" % (name, alen - dlen, plen)) return True args_check = staticmethod(args_check) def __str__(self): return self.token class Variable: """ 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':'News'}} >>> Variable('article.section').resolve(c) 'News' >>> Variable('article').resolve(c) {'section': 'News'} >>> class AClass: pass >>> c = AClass() >>> c.article = AClass() >>> c.article.section = 'News' (The example assumes VARIABLE_ATTRIBUTE_SEPARATOR is '.') """ def __init__(self, var): self.var = var self.literal = None self.lookups = None self.translate = False self.message_context = None if not isinstance(var, str): raise TypeError( "Variable must be a string or number, got %s" % type(var)) 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: is_safe = isinstance(value, SafeData) msgid = value.replace('%', '%%') msgid = mark_safe(msgid) if is_safe else msgid if self.message_context: return pgettext_lazy(self.message_context, msgid) else: return gettext_lazy(msgid) return value def __repr__(self): return "<%s: %r>" % (self.__class__.__name__, self.var) def __str__(self): return self.var def _resolve_lookup(self, context): """ Perform 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 try: # catch-all for silent variable failures for bit in self.lookups: try: # dictionary lookup current = current[bit] # ValueError/IndexError are for numpy.array lookup on # numpy < 1.9 and 1.9+ respectively except (TypeError, AttributeError, KeyError, ValueError, IndexError): try: # attribute lookup # Don't return class attributes if the class is the context: if isinstance(current, BaseContext) and getattr(type(current), bit): raise AttributeError current = getattr(current, bit) except (TypeError, AttributeError): # Reraise if the exception was raised by a @property if not isinstance(current, BaseContext) and bit in dir(current): raise 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 if callable(current): if getattr(current, 'do_not_call_in_templates', False): pass elif getattr(current, 'alters_data', False): current = context.template.engine.string_if_invalid else: try: # method call (assuming no args required) current = current() except TypeError: try: inspect.getcallargs(current) except TypeError: # arguments *were* required current = context.template.engine.string_if_invalid # invalid method call else: raise except Exception as e: template_name = getattr(context, 'template_name', None) or 'unknown' logger.debug( "Exception while resolving variable '%s' in template '%s'.", bit, template_name, exc_info=True, ) if getattr(e, 'silent_variable_failure', False): current = context.template.engine.string_if_invalid else: raise return current class Node: # 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 child_nodelists = ('nodelist',) token = None def render(self, context): """ Return the node rendered as a string. """ pass def render_annotated(self, context): """ Render the node. If debug is True and an exception occurs during rendering, the exception is annotated with contextual line information where it occurred in the template. For internal usage this method is preferred over using the render method directly. """ try: return self.render(context) except Exception as e: if context.template.engine.debug and not hasattr(e, 'template_debug'): e.template_debug = context.render_context.template.get_exception_info(e, self.token) raise 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) for attr in self.child_nodelists: nodelist = getattr(self, attr, None) if nodelist: nodes.extend(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): bit = node.render_annotated(context) else: bit = node bits.append(str(bit)) return mark_safe(''.join(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 class TextNode(Node): def __init__(self, s): self.s = s def __repr__(self): return "<%s: %r>" % (self.__class__.__name__, self.s[:25]) def render(self, context): return self.s def render_value_in_context(value, context): """ Convert any value to a string to become part of a rendered template. This means escaping, if required, and conversion to a string. If value is a string, it's expected to already be translated. """ value = template_localtime(value, use_tz=context.use_tz) value = localize(value, use_l10n=context.use_l10n) if context.autoescape: if not issubclass(type(value), str): value = str(value) return conditional_escape(value) else: return str(value) class VariableNode(Node): def __init__(self, filter_expression): self.filter_expression = filter_expression def __repr__(self): return "<Variable Node: %s>" % 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) # Regex for token keyword arguments kwarg_re = re.compile(r"(?:(\w+)=)?(.+)") def token_kwargs(bits, parser, support_legacy=False): """ Parse token keyword arguments and return a dictionary of the arguments retrieved from the ``bits`` token list. `bits` is a list containing the remainder of the token (split by spaces) that is to be checked for arguments. Valid arguments are removed from this list. `support_legacy` - if True, the legacy format ``1 as foo`` is accepted. Otherwise, only the standard ``foo=1`` format is allowed. There is no requirement for all remaining token ``bits`` to be keyword arguments, so return the dictionary as soon as an invalid argument format is reached. """ if not bits: return {} match = kwarg_re.match(bits[0]) kwarg_format = match and match.group(1) if not kwarg_format: if not support_legacy: return {} if len(bits) < 3 or bits[1] != 'as': return {} kwargs = {} while bits: if kwarg_format: match = kwarg_re.match(bits[0]) if not match or not match.group(1): return kwargs key, value = match.groups() del bits[:1] else: if len(bits) < 3 or bits[1] != 'as': return kwargs key, value = bits[2], bits[0] del bits[:3] kwargs[key] = parser.compile_filter(value) if bits and not kwarg_format: if bits[0] != 'and': return kwargs del bits[:1] return kwargs
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