def __init__(self, loopvars, sequence, is_reversed, nodelist_loop, nodelist_empty=None):
self.loopvars, self.sequence = loopvars, sequence
self.is_reversed = is_reversed
self.nodelist_loop = nodelist_loop
if nodelist_empty is None:
self.nodelist_empty = NodeList()
else:
self.nodelist_empty = nodelist_empty
def render(self, context):
if "forloop" in context:
parentloop = context["forloop"]
else:
parentloop = {}
context.push()
try:
values = self.sequence.resolve(context, True)
except VariableDoesNotExist:
values = []
if values is None:
values = []
if not hasattr(values, "__len__"):
values = list(values)
len_values = len(values)
if len_values < 1:
context.pop()
return self.nodelist_empty.render(context)
nodelist = NodeList()
if self.is_reversed:
values = reversed(values)
unpack = len(self.loopvars) > 1
# Create a forloop value in the context. We'll update counters on each
# iteration just below.
loop_dict = context["forloop"] = {"parentloop": parentloop}
for i, item in enumerate(values):
# Shortcuts for current loop iteration number.
loop_dict["counter0"] = i
loop_dict["counter"] = i + 1
# Reverse counter iteration numbers.
loop_dict["revcounter"] = len_values - i
loop_dict["revcounter0"] = len_values - i - 1
# Boolean values designating first and last times through loop.
loop_dict["first"] = i == 0
loop_dict["last"] = i == len_values - 1
pop_context = False
if unpack:
# If there are multiple loop variables, unpack the item into
# them.
try:
unpacked_vars = dict(zip(self.loopvars, item))
except TypeError:
pass
else:
pop_context = True
context.update(unpacked_vars)
else:
context[self.loopvars[0]] = item
# In TEMPLATE_DEBUG mode provide source of the node which
# actually raised the exception
if settings.TEMPLATE_DEBUG:
for node in self.nodelist_loop:
try:
nodelist.append(node.render(context))
except Exception as e:
if not hasattr(e, "django_template_source"):
e.django_template_source = node.source
raise
else:
for node in self.nodelist_loop:
nodelist.append(node.render(context))
if pop_context:
# The loop variables were pushed on to the context so pop them
# off again. This is necessary because the tag lets the length
# of loopvars differ to the length of each set of items and we
# don't want to leave any vars from the previous loop on the
# context.
context.pop()
context.pop()
return nodelist.render(context)
