154 lines
5.6 KiB
Python
154 lines
5.6 KiB
Python
"""
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Wrapper class that takes a list of template loaders as an argument and attempts
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to load templates from them in order, caching the result.
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"""
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import hashlib
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import warnings
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from django.template import Origin, Template, TemplateDoesNotExist
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from django.utils.deprecation import RemovedInDjango20Warning
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from django.utils.encoding import force_bytes
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from django.utils.inspect import func_supports_parameter
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from .base import Loader as BaseLoader
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class Loader(BaseLoader):
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def __init__(self, engine, loaders):
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self.template_cache = {}
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self.find_template_cache = {} # RemovedInDjango20Warning
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self.get_template_cache = {}
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self.loaders = engine.get_template_loaders(loaders)
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super(Loader, self).__init__(engine)
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def get_contents(self, origin):
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return origin.loader.get_contents(origin)
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def get_template(self, template_name, template_dirs=None, skip=None):
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key = self.cache_key(template_name, template_dirs, skip)
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cached = self.get_template_cache.get(key)
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if cached:
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if isinstance(cached, TemplateDoesNotExist):
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raise cached
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return cached
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try:
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template = super(Loader, self).get_template(
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template_name, template_dirs, skip,
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)
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except TemplateDoesNotExist as e:
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self.get_template_cache[key] = e
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raise
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else:
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self.get_template_cache[key] = template
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return template
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def get_template_sources(self, template_name, template_dirs=None):
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for loader in self.loaders:
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args = [template_name]
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# RemovedInDjango20Warning: Add template_dirs for compatibility
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# with old loaders
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if func_supports_parameter(loader.get_template_sources, 'template_dirs'):
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args.append(template_dirs)
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for origin in loader.get_template_sources(*args):
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yield origin
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def cache_key(self, template_name, template_dirs, skip=None):
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"""
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Generate a cache key for the template name, dirs, and skip.
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If skip is provided, only origins that match template_name are included
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in the cache key. This ensures each template is only parsed and cached
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once if contained in different extend chains like:
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x -> a -> a
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y -> a -> a
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z -> a -> a
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"""
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dirs_prefix = ''
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skip_prefix = ''
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if skip:
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matching = [origin.name for origin in skip if origin.template_name == template_name]
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if matching:
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skip_prefix = self.generate_hash(matching)
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if template_dirs:
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dirs_prefix = self.generate_hash(template_dirs)
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return ("%s-%s-%s" % (template_name, skip_prefix, dirs_prefix)).strip('-')
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def generate_hash(self, values):
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return hashlib.sha1(force_bytes('|'.join(values))).hexdigest()
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@property
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def supports_recursion(self):
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"""
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RemovedInDjango20Warning: This is an internal property used by the
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ExtendsNode during the deprecation of non-recursive loaders.
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"""
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return all(hasattr(loader, 'get_contents') for loader in self.loaders)
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def find_template(self, name, dirs=None):
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"""
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RemovedInDjango20Warning: An internal method to lookup the template
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name in all the configured loaders.
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"""
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key = self.cache_key(name, dirs)
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try:
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result = self.find_template_cache[key]
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except KeyError:
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result = None
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for loader in self.loaders:
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try:
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template, display_name = loader(name, dirs)
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except TemplateDoesNotExist:
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pass
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else:
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origin = Origin(
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name=display_name,
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template_name=name,
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loader=loader,
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)
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result = template, origin
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break
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self.find_template_cache[key] = result
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if result:
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return result
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else:
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self.template_cache[key] = TemplateDoesNotExist
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raise TemplateDoesNotExist(name)
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def load_template(self, template_name, template_dirs=None):
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warnings.warn(
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'The load_template() method is deprecated. Use get_template() '
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'instead.', RemovedInDjango20Warning,
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)
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key = self.cache_key(template_name, template_dirs)
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template_tuple = self.template_cache.get(key)
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# A cached previous failure:
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if template_tuple is TemplateDoesNotExist:
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raise TemplateDoesNotExist
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elif template_tuple is None:
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template, origin = self.find_template(template_name, template_dirs)
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if not hasattr(template, 'render'):
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try:
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template = Template(template, origin, template_name, self.engine)
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except TemplateDoesNotExist:
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# If compiling the template we found raises TemplateDoesNotExist,
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# back off to returning the source and display name for the template
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# we were asked to load. This allows for correct identification (later)
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# of the actual template that does not exist.
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self.template_cache[key] = (template, origin)
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self.template_cache[key] = (template, None)
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return self.template_cache[key]
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def reset(self):
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"Empty the template cache."
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self.template_cache.clear()
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self.find_template_cache.clear() # RemovedInDjango20Warning
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self.get_template_cache.clear()
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