143 lines
6.0 KiB
Python
143 lines
6.0 KiB
Python
"Wrapper for loading templates from storage of some sort (e.g. files or db)"
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import template
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from template_file import load_template_source
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class ExtendsError(Exception):
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pass
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def get_template(template_name):
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"""
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Returns a compiled template.Template object for the given template name,
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handling template inheritance recursively.
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"""
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return get_template_from_string(load_template_source(template_name))
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def get_template_from_string(source):
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"""
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Returns a compiled template.Template object for the given template code,
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handling template inheritance recursively.
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"""
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return template.Template(source)
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def select_template(template_name_list):
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"Given a list of template names, returns the first that can be loaded."
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for template_name in template_name_list:
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try:
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return get_template(template_name)
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except template.TemplateDoesNotExist:
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continue
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# If we get here, none of the templates could be loaded
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raise template.TemplateDoesNotExist, ', '.join(template_name_list)
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class SuperBlock:
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"This implements the ability for {{ block.super }} to render the parent block's contents"
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def __init__(self, context, nodelist):
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self.context, self.nodelist = context, nodelist
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def super(self):
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if self.nodelist:
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return self.nodelist.render(self.context)
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else:
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return ''
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class BlockNode(template.Node):
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def __init__(self, name, nodelist):
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self.name, self.nodelist = name, nodelist
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def __repr__(self):
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return "<Block Node: %s. Contents: %r>" % (self.name, self.nodelist)
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def render(self, context):
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context.push()
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nodelist = hasattr(self, 'original_node_list') and self.original_node_list or None
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context['block'] = SuperBlock(context, nodelist)
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result = self.nodelist.render(context)
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context.pop()
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return result
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class ExtendsNode(template.Node):
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def __init__(self, nodelist, parent_name, parent_name_var, template_dirs=None):
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self.nodelist = nodelist
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self.parent_name, self.parent_name_var = parent_name, parent_name_var
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self.template_dirs = template_dirs
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def get_parent(self, context):
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if self.parent_name_var:
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self.parent_name = template.resolve_variable_with_filters(self.parent_name_var, context)
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parent = self.parent_name
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if not parent:
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error_msg = "Invalid template name in 'extends' tag: %r." % parent
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if self.parent_name_var:
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error_msg += " Got this from the %r variable." % self.parent_name_var
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raise template.TemplateSyntaxError, error_msg
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try:
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return get_template_from_string(load_template_source(parent, self.template_dirs))
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except template.TemplateDoesNotExist:
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raise template.TemplateSyntaxError, "Template %r cannot be extended, because it doesn't exist" % parent
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def render(self, context):
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compiled_parent = self.get_parent(context)
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parent_is_child = isinstance(compiled_parent.nodelist[0], ExtendsNode)
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parent_blocks = dict([(n.name, n) for n in compiled_parent.nodelist.get_nodes_by_type(BlockNode)])
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for block_node in self.nodelist.get_nodes_by_type(BlockNode):
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# Check for a BlockNode with this node's name, and replace it if found.
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try:
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parent_block = parent_blocks[block_node.name]
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except KeyError:
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# This BlockNode wasn't found in the parent template, but the
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# parent block might be defined in the parent's *parent*, so we
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# add this BlockNode to the parent's ExtendsNode nodelist, so
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# it'll be checked when the parent node's render() is called.
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if parent_is_child:
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compiled_parent.nodelist[0].nodelist.append(block_node)
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else:
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# Save the original nodelist. It's used by BlockNode.
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parent_block.original_node_list = parent_block.nodelist
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parent_block.nodelist = block_node.nodelist
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return compiled_parent.render(context)
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def do_block(parser, token):
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"""
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Define a block that can be overridden by child templates.
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"""
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bits = token.contents.split()
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if len(bits) != 2:
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raise template.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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raise template.TemplateSyntaxError, "'%s' tag with name '%s' appears more than once" % (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(('endblock',))
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parser.delete_first_token()
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return BlockNode(block_name, nodelist)
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def do_extends(parser, token):
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"""
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Signal that this template extends a parent template.
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This tag may be used in two ways: ``{% extends "base" %}`` (with quotes)
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uses the literal value "base" as the name of the parent template to extend,
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or ``{% entends variable %}`` uses the value of ``variable`` as the name
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of the parent template to extend.
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"""
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bits = token.contents.split()
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if len(bits) != 2:
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raise template.TemplateSyntaxError, "'%s' takes one argument" % bits[0]
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parent_name, parent_name_var = None, None
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if (bits[1].startswith('"') and bits[1].endswith('"')) or (bits[1].startswith("'") and bits[1].endswith("'")):
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parent_name = bits[1][1:-1]
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else:
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parent_name_var = bits[1]
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nodelist = parser.parse()
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if nodelist.get_nodes_by_type(ExtendsNode):
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raise template.TemplateSyntaxError, "'%s' cannot appear more than once in the same template" % bits[0]
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return ExtendsNode(nodelist, parent_name, parent_name_var)
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template.register_tag('block', do_block)
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template.register_tag('extends', do_extends)
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