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80 | """
Tags for performing basic value comparisons in templates.
"""
from django import template
from template_utils import comparisons
class ComparisonNode(template.Node):
def __init__(self, comparison, nodelist_true, nodelist_false, negate, *vars):
self.vars = map(template.Variable, vars)
self.comparison = comparison
self.negate = negate
self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false
def render(self, context):
resolve = lambda var: var.resolve(context)
try:
if comparisons[self.comparison](
*[var.resolve(context) for var in self.vars]):
if self.negate:
return self.nodelist_false.render(context)
return self.nodelist_true.render(context)
# If either variable fails to resolve, return nothing.
except template.VariableDoesNotExist:
return ''
# If the types don't permit comparison, return nothing.
except TypeError:
return ''
if self.negate:
return self.nodelist_true.render(context)
return self.nodelist_false.render(context)
def do_comparison(parser, token):
"""
Compares two values.
Syntax::
{% if_[comparison] [var1] [var2] [var...] [negate] %}
...
{% else %}
...
{% endif_[comparison] %}
Supported comparisons are ``match``, ``find``, ``startswith``, ``endswith``,
``less``, ``less_or_equal``, ``greater`` and ``greater_or_equal``.
Examples::
{% if_less some_object.id 3 %}
<p>{{ some_object }} has an id less than 3.</p>
{% endif_less %}
{% if_match request.path '^/$' %}
<p>Welcome home</p>
{% endif_match %}
"""
negate = False
bits = token.contents.split()
end_tag = 'end' + bits[0]
nodelist_true = parser.parse(('else', end_tag))
token = parser.next_token()
if token.contents == 'else':
nodelist_false = parser.parse((end_tag,))
parser.delete_first_token()
else:
nodelist_false = template.NodeList()
if bits[-1] == 'negate':
bits = bits[:-1]
negate = True
comparison = bits[0].split('if_')[1]
return ComparisonNode(comparison, nodelist_true, nodelist_false, negate, *bits[1:])
register = template.Library()
for tag_name in comparisons:
register.tag('if_%s' % tag_name, do_comparison)
|
