+# Source: http://djangosnippets.org/snippets/967/
+# Author: adurdin
+# Posted: August 13, 2008
+#
+#
+# We can use it based on djangosnippets Terms of Service:
+# (http://djangosnippets.org/about/tos/)
+#
+# 2. That you grant any third party who sees the code you post
+# a royalty-free, non-exclusive license to copy and distribute that code
+# and to make and distribute derivative works based on that code. You may
+# include license terms in snippets you post, if you wish to use
+# a particular license (such as the BSD license or GNU GPL), but that
+# license must permit royalty-free copying, distribution and modification
+# of the code to which it is applied.
+
+from django import template
+from django.template import Library, Node, VariableDoesNotExist
+
+register = Library()
+
+
+@register.tag(name="switch")
+def do_switch(parser, token):
+ """
+ The ``{% switch %}`` tag compares a variable against one or more values in
+ ``{% case %}`` tags, and outputs the contents of the matching block. An
+ optional ``{% else %}`` tag sets off the default output if no matches
+ could be found::
+
+ {% switch result_count %}
+ {% case 0 %}
+ There are no search results.
+ {% case 1 %}
+ There is one search result.
+ {% else %}
+ Jackpot! Your search found {{ result_count }} results.
+ {% endswitch %}
+
+ Each ``{% case %}`` tag can take multiple values to compare the variable
+ against::
+
+ {% switch username %}
+ {% case "Jim" "Bob" "Joe" %}
+ Me old mate {{ username }}! How ya doin?
+ {% else %}
+ Hello {{ username }}
+ {% endswitch %}
+ """
+ bits = token.contents.split()
+ tag_name = bits[0]
+ if len(bits) != 2:
+ raise template.TemplateSyntaxError("'%s' tag requires one argument" % tag_name)
+ variable = parser.compile_filter(bits[1])
+
+ class BlockTagList(object):
+ # This is a bit of a hack, as it embeds knowledge of the behaviour
+ # of Parser.parse() relating to the "parse_until" argument.
+ def __init__(self, *names):
+ self.names = set(names)
+ def __contains__(self, token_contents):
+ name = token_contents.split()[0]
+ return name in self.names
+
+ # Skip over everything before the first {% case %} tag
+ parser.parse(BlockTagList('case', 'endswitch'))
+
+ cases = []
+ token = parser.next_token()
+ got_case = False
+ got_else = False
+ while token.contents != 'endswitch':
+ nodelist = parser.parse(BlockTagList('case', 'else', 'endswitch'))
+
+ if got_else:
+ raise template.TemplateSyntaxError("'else' must be last tag in '%s'." % tag_name)
+
+ contents = token.contents.split()
+ token_name, token_args = contents[0], contents[1:]
+
+ if token_name == 'case':
+ tests = map(parser.compile_filter, token_args)
+ case = (tests, nodelist)
+ got_case = True
+ else:
+ # The {% else %} tag
+ case = (None, nodelist)
+ got_else = True
+ cases.append(case)
+ token = parser.next_token()
+
+ if not got_case:
+ raise template.TemplateSyntaxError("'%s' must have at least one 'case'." % tag_name)
+
+ return SwitchNode(variable, cases)
+
+class SwitchNode(Node):
+ def __init__(self, variable, cases):
+ self.variable = variable
+ self.cases = cases
+
+ def __repr__(self):
+ return "<Switch node>"
+
+ def __iter__(self):
+ for tests, nodelist in self.cases:
+ for node in nodelist:
+ yield node
+
+ def get_nodes_by_type(self, nodetype):
+ nodes = []
+ if isinstance(self, nodetype):
+ nodes.append(self)
+ for tests, nodelist in self.cases:
+ nodes.extend(nodelist.get_nodes_by_type(nodetype))
+ return nodes
+
+ def render(self, context):
+ try:
+ value_missing = False
+ value = self.variable.resolve(context, True)
+ except VariableDoesNotExist:
+ no_value = True
+ value_missing = None
+
+ for tests, nodelist in self.cases:
+ if tests is None:
+ return nodelist.render(context)
+ elif not value_missing:
+ for test in tests:
+ test_value = test.resolve(context, True)
+ if value == test_value:
+ return nodelist.render(context)
+ else:
+ return ""
fnp / wolnelektury.git / commitdiff