A rewrite of the reverse URL parsing: the reverse() call and the "url" template tag. (a63a83e5) · Commits · Dom Sekotill / django

django/core/urlresolvers.py

+29 −86

Original line number	Diff line number	Diff line
		@@ -13,12 +13,14 @@ from django.http import Http404
		from django.core.exceptions import ImproperlyConfigured, ViewDoesNotExist
		from django.utils.encoding import iri_to_uri, force_unicode, smart_str
		from django.utils.functional import memoize
		from django.utils.regex_helper import normalize
		from django.utils.thread_support import currentThread

		try:
		reversed
		except NameError:
		from django.utils.itercompat import reversed # Python 2.3 fallback
		from sets import Set as set

		_resolver_cache = {} # Maps urlconf modules to RegexURLResolver instances.
		_callable_cache = {} # Maps view and url pattern names to their view functions.
		@@ -78,66 +80,6 @@ def get_mod_func(callback):
		return callback, ''
		return callback[:dot], callback[dot+1:]

		def reverse_helper(regex, args, *kwargs):
		"""
		Does a "reverse" lookup -- returns the URL for the given args/kwargs.
		The args/kwargs are applied to the given compiled regular expression.
		For example:

		>>> reverse_helper(re.compile('^places/(\d+)/$'), 3)
		'places/3/'
		>>> reverse_helper(re.compile('^places/(?P<id>\d+)/$'), id=3)
		'places/3/'
		>>> reverse_helper(re.compile('^people/(?P<state>\w\w)/(\w+)/$'), 'adrian', state='il')
		'people/il/adrian/'

		Raises NoReverseMatch if the args/kwargs aren't valid for the regex.
		"""
		# TODO: Handle nested parenthesis in the following regex.
		result = re.sub(r'$([^)]+)$', MatchChecker(args, kwargs), regex.pattern)
		return result.replace('^', '').replace('$', '').replace('\\', '')

		class MatchChecker(object):
		"Class used in reverse RegexURLPattern lookup."
		def __init__(self, args, kwargs):
		self.args, self.kwargs = args, kwargs
		self.current_arg = 0

		def __call__(self, match_obj):
		# match_obj.group(1) is the contents of the parenthesis.
		# First we need to figure out whether it's a named or unnamed group.
		#
		grouped = match_obj.group(1)
		m = re.search(r'^\?P<(\w+)>(.*?)$', grouped, re.UNICODE)
		if m: # If this was a named group...
		# m.group(1) is the name of the group
		# m.group(2) is the regex.
		try:
		value = self.kwargs[m.group(1)]
		except KeyError:
		# It was a named group, but the arg was passed in as a
		# positional arg or not at all.
		try:
		value = self.args[self.current_arg]
		self.current_arg += 1
		except IndexError:
		# The arg wasn't passed in.
		raise NoReverseMatch('Not enough positional arguments passed in')
		test_regex = m.group(2)
		else: # Otherwise, this was a positional (unnamed) group.
		try:
		value = self.args[self.current_arg]
		self.current_arg += 1
		except IndexError:
		# The arg wasn't passed in.
		raise NoReverseMatch('Not enough positional arguments passed in')
		test_regex = grouped
		# Note we're using re.match here on purpose because the start of
		# to string needs to match.
		if not re.match(test_regex + '$', force_unicode(value), re.UNICODE):
		raise NoReverseMatch("Value %r didn't match regular expression %r" % (value, test_regex))
		return force_unicode(value)

		class RegexURLPattern(object):
		def __init__(self, regex, callback, default_args=None, name=None):
		# regex is a string representing a regular expression.
		@@ -194,21 +136,6 @@ class RegexURLPattern(object):
		return self._callback
		callback = property(_get_callback)

		def reverse(self, viewname, args, *kwargs):
		mod_name, func_name = get_mod_func(viewname)
		try:
		lookup_view = getattr(__import__(mod_name, {}, {}, ['']), func_name)
		except ImportError, e:
		raise NoReverseMatch("Could not import '%s': %s" % (mod_name, e))
		except AttributeError, e:
		raise NoReverseMatch("'%s' has no attribute '%s'" % (mod_name, func_name))
		if lookup_view != self.callback:
		raise NoReverseMatch("Reversed view '%s' doesn't match the expected callback ('%s')." % (viewname, self.callback))
		return self.reverse_helper(args, *kwargs)

		def reverse_helper(self, args, *kwargs):
		return reverse_helper(self.regex, args, *kwargs)

		class RegexURLResolver(object):
		def __init__(self, regex, urlconf_name, default_kwargs=None):
		# regex is a string representing a regular expression.
		@@ -225,12 +152,21 @@ class RegexURLResolver(object):
		def _get_reverse_dict(self):
		if not self._reverse_dict and hasattr(self.urlconf_module, 'urlpatterns'):
		for pattern in reversed(self.urlconf_module.urlpatterns):
		p_pattern = pattern.regex.pattern
		if p_pattern.startswith('^'):
		p_pattern = p_pattern[1:]
		if isinstance(pattern, RegexURLResolver):
		for key, value in pattern.reverse_dict.iteritems():
		self._reverse_dict[key] = (pattern,) + value
		parent = normalize(pattern.regex.pattern)
		for name, (matches, pat) in pattern.reverse_dict.iteritems():
		new_matches = []
		for piece, p_args in parent:
		new_matches.extend([(piece + suffix, p_args + args)
		for (suffix, args) in matches])
		self._reverse_dict[name] = new_matches, p_pattern + pat
		else:
		self._reverse_dict[pattern.callback] = (pattern,)
		self._reverse_dict[pattern.name] = (pattern,)
		bits = normalize(p_pattern)
		self._reverse_dict[pattern.callback] = bits, p_pattern
		self._reverse_dict[pattern.name] = bits, p_pattern
		return self._reverse_dict
		reverse_dict = property(_get_reverse_dict)

		@@ -281,20 +217,27 @@ class RegexURLResolver(object):
		return self._resolve_special('500')

		def reverse(self, lookup_view, args, *kwargs):
		if args and kwargs:
		raise ValueError("Don't mix args and *kwargs in call to reverse()!")
		try:
		lookup_view = get_callable(lookup_view, True)
		except (ImportError, AttributeError), e:
		raise NoReverseMatch("Error importing '%s': %s." % (lookup_view, e))
		if lookup_view in self.reverse_dict:
		return u''.join([reverse_helper(part.regex, args, *kwargs) for part in self.reverse_dict[lookup_view]])
		possibilities, pattern = self.reverse_dict.get(lookup_view, [(), ()])
		for result, params in possibilities:
		if args:
		if len(args) != len(params):
		continue
		candidate = result % dict(zip(params, args))
		else:
		if set(kwargs.keys()) != set(params):
		continue
		candidate = result % kwargs
		if re.search('^%s' % pattern, candidate, re.UNICODE):
		return candidate
		raise NoReverseMatch("Reverse for '%s' with arguments '%s' and keyword "
		"arguments '%s' not found." % (lookup_view, args, kwargs))

		def reverse_helper(self, lookup_view, args, *kwargs):
		sub_match = self.reverse(lookup_view, args, *kwargs)
		result = reverse_helper(self.regex, args, *kwargs)
		return result + sub_match

		def resolve(path, urlconf=None):
		return get_resolver(urlconf).resolve(path)

django/utils/regex_helper.py

0 → 100644

+323 −0

Original line number	Diff line number	Diff line
		"""
		Functions for reversing a regular expression (used in reverse URL resolving).
		Used internally by Django and not intended for external use.

		This is not, and is not intended to be, a complete reg-exp decompiler. It
		should be good enough for a large class of URLS, however.
		"""

		# Mapping of an escape character to a representative of that class. So, e.g.,
		# "\w" is replaced by "x" in a reverse URL. A value of None means to ignore
		# this sequence. Any missing key is mapped to itself.
		ESCAPE_MAPPINGS = {
		"A": None,
		"b": None,
		"B": None,
		"d": '0',
		"D": "x",
		"s": " ",
		"S": "x",
		"w": "x",
		"W": "!",
		"Z": None,
		}

		class Choice(list):
		"""
		Used to represent multiple possibilities at this point in a pattern string.
		We use a distinguished type, rather than a list, so that the usage in the
		code is clear.
		"""

		class Group(list):
		"""
		Used to represent a capturing group in the pattern string.
		"""

		class NonCapture(list):
		"""
		Used to represent a non-capturing group in the pattern string.
		"""

		def normalize(pattern):
		"""
		Given a reg-exp pattern, normalizes it to a list of forms that suffice for
		reverse matching. This does the following:

		(1) For any repeating sections, keeps the minimum number of occurrences
		permitted (this means zero for optional groups).
		(2) If an optional group includes parameters, include one occurrence of
		that group (along with the zero occurrence case from step (1)).
		(3) Select the first (essentially an arbitrary) element from any character
		class. Select an arbitrary character for any unordered class (e.g. '.'
		or '\w') in the pattern.
		(5) Ignore comments and any of the reg-exp flags that won't change
		what we construct ("iLmsu"). "(?x)" is an error, however.
		(6) Raise an error on all other non-capturing (?...) forms (e.g.
		look-ahead and look-behind matches) and any disjunctive ('\|')
		constructs.

		Django's URLs for forward resolving are either all positional arguments or
		all keyword arguments. That is assumed here, as well. Although reverse
		resolving can be done using positional args when keyword args are
		specified, the two cannot be mixed in the same reverse() call.
		"""
		# Do a linear scan to work out the special features of this pattern. The
		# idea is that we scan once here and collect all the information we need to
		# make future decisions.
		result = []
		non_capturing_groups = []
		consume_next = True
		pattern_iter = next_char(iter(pattern))
		num_args = 0

		# A "while" loop is used here because later on we need to be able to peek
		# at the next character and possibly go around without consuming another
		# one at the top of the loop.
		ch, escaped = pattern_iter.next()
		try:
		while True:
		if escaped:
		result.append(ch)
		elif ch == '.':
		# Replace "any character" with an arbitrary representative.
		result.append("x")
		elif ch == '\|':
		# FIXME: One day we'll should do this, but not in 1.0.
		raise NotImplementedError
		elif ch == "^":
		pass
		elif ch == '$':
		break
		elif ch == ')':
		# This can only be the end of a non-capturing group, since all
		# other unescaped parentheses are handled by the grouping
		# section later (and the full group is handled there).
		#
		# We regroup everything inside the capturing group so that it
		# can be quantified, if necessary.
		start = non_capturing_groups.pop()
		inner = NonCapture(result[start:])
		result = result[:start] + [inner]
		elif ch == '[':
		# Replace ranges with the first character in the range.
		ch, escaped = pattern_iter.next()
		result.append(ch)
		ch, escaped = pattern_iter.next()
		while escaped or ch != ']':
		ch, escaped = pattern_iter.next()
		elif ch == '(':
		# Some kind of group.
		ch, escaped = pattern_iter.next()
		if ch != '?' or escaped:
		# A positional group
		name = "_%d" % num_args
		num_args += 1
		result.append(Group((("%%(%s)s" % name), name)))
		walk_to_end(ch, pattern_iter)
		else:
		ch, escaped = pattern_iter.next()
		if ch in "iLmsu#":
		# All of these are ignorable. Walk to the end of the
		# group.
		walk_to_end(ch, pattern_iter)
		elif ch == ':':
		# Non-capturing group
		non_capturing_groups.append(len(result))
		elif ch != 'P':
		# Anything else, other than a named group, is something
		# we cannot reverse.
		raise ValueError("Non-reversible reg-exp portion: '(?%s'" % ch)
		else:
		ch, escaped = pattern_iter.next()
		if ch != '<':
		raise ValueError("Non-reversible reg-exp portion: '(?P%s'" % ch)
		# We are in a named capturing group. Extra the name and
		# then skip to the end.
		name = []
		ch, escaped = pattern_iter.next()
		while ch != '>':
		name.append(ch)
		ch, escaped = pattern_iter.next()
		param = ''.join(name)
		result.append(Group((("%%(%s)s" % param), param)))
		walk_to_end(ch, pattern_iter)
		elif ch in "*?+{":
		# Quanitifers affect the previous item in the result list.
		count, ch = get_quantifier(ch, pattern_iter)
		if ch:
		# We had to look ahead, but it wasn't need to compute the
		# quanitifer, so use this character next time around the
		# main loop.
		consume_next = False

		if count == 0:
		if contains(result[-1], Group):
		# If we are quantifying a capturing group (or
		# something containing such a group) and the minimum is
		# zero, we must also handle the case of one occurrence
		# being present. All the quantifiers (except {0,0},
		# which we conveniently ignore) that have a 0 minimum
		# also allow a single occurrence.
		result[-1] = Choice([None, result[-1]])
		else:
		result.pop()
		elif count > 1:
		result.extend([result[-1]] * (count - 1))
		else:
		# Anything else is a literal.
		result.append(ch)

		if consume_next:
		ch, escaped = pattern_iter.next()
		else:
		consume_next = True
		except StopIteration:
		pass
		except NotImplementedError:
		# A case of using the disjunctive form. No results for you!
		return zip([''], [[]])

		return zip(*flatten_result(result))

		def next_char(input_iter):
		"""
		An iterator that yields the next character from "pattern_iter", respecting
		escape sequences. An escaped character is replaced by a representative of
		its class (e.g. \w -> "x"). If the escaped character is one that is
		skipped, it is not returned (the next character is returned instead).

		Yields the next character, along with a boolean indicating whether it is a
		raw (unescaped) character or not.
		"""
		for ch in input_iter:
		if ch != '\\':
		yield ch, False
		continue
		ch = input_iter.next()
		representative = ESCAPE_MAPPINGS.get(ch, ch)
		if representative is None:
		continue
		yield representative, True

		def walk_to_end(ch, input_iter):
		"""
		The iterator is currently inside a capturing group. We want to walk to the
		close of this group, skipping over any nested groups and handling escaped
		parentheses correctly.
		"""
		if ch == '(':
		nesting = 1
		else:
		nesting = 0
		for ch, escaped in input_iter:
		if escaped:
		continue
		elif ch == '(':
		nesting += 1
		elif ch == ')':
		if not nesting:
		return
		nesting -= 1

		def get_quantifier(ch, input_iter):
		"""
		Parse a quantifier from the input, where "ch" is the first character in the
		quantifier.

		Returns the minimum number of occurences permitted by the quantifier and
		either None or the next character from the input_iter if the next character
		is not part of the quantifier.
		"""
		if ch in '*?+':
		try:
		ch2, escaped = input_iter.next()
		except StopIteration:
		ch2 = None
		if ch2 == '?':
		ch2 = None
		if ch == '+':
		return 1, ch2
		return 0, ch2

		quant = []
		while ch != '}':
		ch, escaped = input_iter.next()
		quant.append(ch)
		values = ''.join(quant).split(',')

		# Consume the trailing '?', if necessary.
		try:
		ch, escaped = input_iter.next()
		except StopIteration:
		ch = None
		if ch == '?':
		ch = None
		return int(values[0]), ch

		def contains(source, inst):
		"""
		Returns True if the "source" contains an instance of "inst". False,
		otherwise.
		"""
		if isinstance(source, inst):
		return True
		if isinstance(source, NonCapture):
		for elt in source:
		if contains(elt, inst):
		return True
		return False

		def flatten_result(source):
		"""
		Turns the given source sequence into a list of reg-exp possibilities and
		their arguments. Returns a list of strings and a list of argument lists.
		Each of the two lists will be of the same length.
		"""
		if source is None:
		return [''], [[]]
		if isinstance(source, Group):
		if source[1] is None:
		params = []
		else:
		params = [source[1]]
		return [source[0]], [params]
		result = ['']
		result_args = [[]]
		pos = last = 0
		for pos, elt in enumerate(source):
		if isinstance(elt, basestring):
		continue
		piece = ''.join(source[last:pos])
		if isinstance(elt, Group):
		piece += elt[0]
		param = elt[1]
		else:
		param = None
		last = pos + 1
		for i in range(len(result)):
		result[i] += piece
		if param:
		result_args[i].append(param)
		if isinstance(elt, (Choice, NonCapture)):
		if isinstance(elt, NonCapture):
		elt = [elt]
		inner_result, inner_args = [], []
		for item in elt:
		res, args = flatten_result(item)
		inner_result.extend(res)
		inner_args.extend(args)
		new_result = []
		new_args = []
		for item, args in zip(result, result_args):
		for i_item, i_args in zip(inner_result, inner_args):
		new_result.append(item + i_item)
		new_args.append(args[:] + i_args)
		result = new_result
		result_args = new_args
		if pos >= last:
		piece = ''.join(source[last:])
		for i in range(len(result)):
		result[i] += piece
		return result, result_args

docs/topics/http/urls.txt

+7 −0

Original line number	Diff line number	Diff line
		@@ -612,6 +612,13 @@ arguments to use in the URL matching. For example::

		.. _URL pattern name: `Naming URL patterns`_

		The ``reverse()`` function can reverse a large variety of regular expression
		patterns for URLs, but not every possible one. The main restriction at the
		moment is that the pattern cannot contain alternative choices using the
		vertical bar (``"\|"``) character. You can quite happily use such patterns for
		matching against incoming URLs and sending them off to views, but you cannot
		reverse such patterns.

		permalink()
		-----------

tests/regressiontests/templates/tests.py

+2 −1

Original line number	Diff line number	Diff line
		@@ -886,7 +886,8 @@ class Templates(unittest.TestCase):
		### URL TAG ########################################################
		# Successes
		'url01': ('{% url regressiontests.templates.views.client client.id %}', {'client': {'id': 1}}, '/url_tag/client/1/'),
		'url02': ('{% url regressiontests.templates.views.client_action client.id, action="update" %}', {'client': {'id': 1}}, '/url_tag/client/1/update/'),
		'url02': ('{% url regressiontests.templates.views.client_action id=client.id,action="update" %}', {'client': {'id': 1}}, '/url_tag/client/1/update/'),
		'url02a': ('{% url regressiontests.templates.views.client_action client.id,"update" %}', {'client': {'id': 1}}, '/url_tag/client/1/update/'),
		'url03': ('{% url regressiontests.templates.views.index %}', {}, '/url_tag/'),
		'url04': ('{% url named.client client.id %}', {'client': {'id': 1}}, '/url_tag/named-client/1/'),
		'url05': (u'{% url метка_оператора v %}', {'v': u'Ω'}, '/url_tag/%D0%AE%D0%BD%D0%B8%D0%BA%D0%BE%D0%B4/%CE%A9/'),

tests/regressiontests/urlpatterns_reverse/included_urls.py

0 → 100644

+8 −0

Original line number	Diff line number	Diff line
		from django.conf.urls.defaults import *
		from views import empty_view

		urlpatterns = patterns('',
		url(r'^$', empty_view, name="inner-nothing"),
		url(r'^extra/(?P<extra>\w+)/$', empty_view, name="inner-extra"),
		url(r'^(?P<one>\d+)\|(?P<two>\d+)/$', empty_view, name="inner-disjunction"),
		)