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from django.template import Library, TemplateSyntaxError |
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from django.template.loader_tags import BlockNode, BLOCK_CONTEXT_KEY |
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register = Library() |
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class IfBlockNode(BlockNode): |
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def __repr__(self): |
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return "<IfBlock Node: %s. Contents: %r>" % (self.name, self.nodelist) |
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def render(self, context): |
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block_context = context.render_context.get(BLOCK_CONTEXT_KEY) |
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context.push() |
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if block_context is None: |
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result = '' |
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else: |
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push = block = block_context.pop(self.name) |
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if block is None or block is self: |
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result = '' |
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else: |
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context.push() |
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# Create new block so we can store context without |
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# thread-safety issues. |
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block = IfBlockNode(block.name, block.nodelist) |
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block.context = context |
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context['block'] = block |
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result = block.nodelist.render(context) |
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context.pop() |
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context['blockoutput'] = result |
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result = self.nodelist.render(context) |
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if push is not None: |
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block_context.push(self.name, push) |
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context.pop() |
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return result |
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def super(self): |
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render_context = self.context.render_context |
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if BLOCK_CONTEXT_KEY in render_context: |
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block = render_context[BLOCK_CONTEXT_KEY].get_block(self.name) |
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if block is not None and not isinstance(block, IfBlockNode): |
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return super(IfBlockNode, self).render(self.context) |
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return '' |
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@register.tag(name="ifblock") |
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def do_ifblock(parser, token): |
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bits = token.contents.split() |
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if len(bits) != 2: |
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raise TemplateSyntaxError("'%s' tag takes only one argument" % bits[0]) |
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block_name = bits[1] |
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# Keep track of the names of BlockNodes found in this template, so we can |
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# check for duplication. |
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try: |
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if block_name in parser.__loaded_blocks: |
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msg = "'%s' tag with name '%s' appears more than once" |
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raise TemplateSyntaxError(msg % (bits[0], block_name)) |
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parser.__loaded_blocks.append(block_name) |
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except AttributeError: # parser.__loaded_blocks isn't a list yet |
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parser.__loaded_blocks = [block_name] |
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nodelist = parser.parse(('endifblock', 'endifblock %s' % block_name)) |
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parser.delete_first_token() |
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return IfBlockNode(block_name, nodelist) |
