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Diffstat (limited to 'python/jinja2/loaders.py')
| -rw-r--r-- | python/jinja2/loaders.py | 481 |
1 files changed, 481 insertions, 0 deletions
diff --git a/python/jinja2/loaders.py b/python/jinja2/loaders.py new file mode 100644 index 0000000..4c79793 --- /dev/null +++ b/python/jinja2/loaders.py @@ -0,0 +1,481 @@ +# -*- coding: utf-8 -*- +""" + jinja2.loaders + ~~~~~~~~~~~~~~ + + Jinja loader classes. + + :copyright: (c) 2017 by the Jinja Team. + :license: BSD, see LICENSE for more details. +""" +import os +import sys +import weakref +from types import ModuleType +from os import path +from hashlib import sha1 +from jinja2.exceptions import TemplateNotFound +from jinja2.utils import open_if_exists, internalcode +from jinja2._compat import string_types, iteritems + + +def split_template_path(template): + """Split a path into segments and perform a sanity check. If it detects + '..' in the path it will raise a `TemplateNotFound` error. + """ + pieces = [] + for piece in template.split('/'): + if path.sep in piece \ + or (path.altsep and path.altsep in piece) or \ + piece == path.pardir: + raise TemplateNotFound(template) + elif piece and piece != '.': + pieces.append(piece) + return pieces + + +class BaseLoader(object): + """Baseclass for all loaders. Subclass this and override `get_source` to + implement a custom loading mechanism. The environment provides a + `get_template` method that calls the loader's `load` method to get the + :class:`Template` object. + + A very basic example for a loader that looks up templates on the file + system could look like this:: + + from jinja2 import BaseLoader, TemplateNotFound + from os.path import join, exists, getmtime + + class MyLoader(BaseLoader): + + def __init__(self, path): + self.path = path + + def get_source(self, environment, template): + path = join(self.path, template) + if not exists(path): + raise TemplateNotFound(template) + mtime = getmtime(path) + with file(path) as f: + source = f.read().decode('utf-8') + return source, path, lambda: mtime == getmtime(path) + """ + + #: if set to `False` it indicates that the loader cannot provide access + #: to the source of templates. + #: + #: .. versionadded:: 2.4 + has_source_access = True + + def get_source(self, environment, template): + """Get the template source, filename and reload helper for a template. + It's passed the environment and template name and has to return a + tuple in the form ``(source, filename, uptodate)`` or raise a + `TemplateNotFound` error if it can't locate the template. + + The source part of the returned tuple must be the source of the + template as unicode string or a ASCII bytestring. The filename should + be the name of the file on the filesystem if it was loaded from there, + otherwise `None`. The filename is used by python for the tracebacks + if no loader extension is used. + + The last item in the tuple is the `uptodate` function. If auto + reloading is enabled it's always called to check if the template + changed. No arguments are passed so the function must store the + old state somewhere (for example in a closure). If it returns `False` + the template will be reloaded. + """ + if not self.has_source_access: + raise RuntimeError('%s cannot provide access to the source' % + self.__class__.__name__) + raise TemplateNotFound(template) + + def list_templates(self): + """Iterates over all templates. If the loader does not support that + it should raise a :exc:`TypeError` which is the default behavior. + """ + raise TypeError('this loader cannot iterate over all templates') + + @internalcode + def load(self, environment, name, globals=None): + """Loads a template. This method looks up the template in the cache + or loads one by calling :meth:`get_source`. Subclasses should not + override this method as loaders working on collections of other + loaders (such as :class:`PrefixLoader` or :class:`ChoiceLoader`) + will not call this method but `get_source` directly. + """ + code = None + if globals is None: + globals = {} + + # first we try to get the source for this template together + # with the filename and the uptodate function. + source, filename, uptodate = self.get_source(environment, name) + + # try to load the code from the bytecode cache if there is a + # bytecode cache configured. + bcc = environment.bytecode_cache + if bcc is not None: + bucket = bcc.get_bucket(environment, name, filename, source) + code = bucket.code + + # if we don't have code so far (not cached, no longer up to + # date) etc. we compile the template + if code is None: + code = environment.compile(source, name, filename) + + # if the bytecode cache is available and the bucket doesn't + # have a code so far, we give the bucket the new code and put + # it back to the bytecode cache. + if bcc is not None and bucket.code is None: + bucket.code = code + bcc.set_bucket(bucket) + + return environment.template_class.from_code(environment, code, + globals, uptodate) + + +class FileSystemLoader(BaseLoader): + """Loads templates from the file system. This loader can find templates + in folders on the file system and is the preferred way to load them. + + The loader takes the path to the templates as string, or if multiple + locations are wanted a list of them which is then looked up in the + given order:: + + >>> loader = FileSystemLoader('/path/to/templates') + >>> loader = FileSystemLoader(['/path/to/templates', '/other/path']) + + Per default the template encoding is ``'utf-8'`` which can be changed + by setting the `encoding` parameter to something else. + + To follow symbolic links, set the *followlinks* parameter to ``True``:: + + >>> loader = FileSystemLoader('/path/to/templates', followlinks=True) + + .. versionchanged:: 2.8+ + The *followlinks* parameter was added. + """ + + def __init__(self, searchpath, encoding='utf-8', followlinks=False): + if isinstance(searchpath, string_types): + searchpath = [searchpath] + self.searchpath = list(searchpath) + self.encoding = encoding + self.followlinks = followlinks + + def get_source(self, environment, template): + pieces = split_template_path(template) + for searchpath in self.searchpath: + filename = path.join(searchpath, *pieces) + f = open_if_exists(filename) + if f is None: + continue + try: + contents = f.read().decode(self.encoding) + finally: + f.close() + + mtime = path.getmtime(filename) + + def uptodate(): + try: + return path.getmtime(filename) == mtime + except OSError: + return False + return contents, filename, uptodate + raise TemplateNotFound(template) + + def list_templates(self): + found = set() + for searchpath in self.searchpath: + walk_dir = os.walk(searchpath, followlinks=self.followlinks) + for dirpath, dirnames, filenames in walk_dir: + for filename in filenames: + template = os.path.join(dirpath, filename) \ + [len(searchpath):].strip(os.path.sep) \ + .replace(os.path.sep, '/') + if template[:2] == './': + template = template[2:] + if template not in found: + found.add(template) + return sorted(found) + + +class PackageLoader(BaseLoader): + """Load templates from python eggs or packages. It is constructed with + the name of the python package and the path to the templates in that + package:: + + loader = PackageLoader('mypackage', 'views') + + If the package path is not given, ``'templates'`` is assumed. + + Per default the template encoding is ``'utf-8'`` which can be changed + by setting the `encoding` parameter to something else. Due to the nature + of eggs it's only possible to reload templates if the package was loaded + from the file system and not a zip file. + """ + + def __init__(self, package_name, package_path='templates', + encoding='utf-8'): + from pkg_resources import DefaultProvider, ResourceManager, \ + get_provider + provider = get_provider(package_name) + self.encoding = encoding + self.manager = ResourceManager() + self.filesystem_bound = isinstance(provider, DefaultProvider) + self.provider = provider + self.package_path = package_path + + def get_source(self, environment, template): + pieces = split_template_path(template) + p = '/'.join((self.package_path,) + tuple(pieces)) + if not self.provider.has_resource(p): + raise TemplateNotFound(template) + + filename = uptodate = None + if self.filesystem_bound: + filename = self.provider.get_resource_filename(self.manager, p) + mtime = path.getmtime(filename) + def uptodate(): + try: + return path.getmtime(filename) == mtime + except OSError: + return False + + source = self.provider.get_resource_string(self.manager, p) + return source.decode(self.encoding), filename, uptodate + + def list_templates(self): + path = self.package_path + if path[:2] == './': + path = path[2:] + elif path == '.': + path = '' + offset = len(path) + results = [] + def _walk(path): + for filename in self.provider.resource_listdir(path): + fullname = path + '/' + filename + if self.provider.resource_isdir(fullname): + _walk(fullname) + else: + results.append(fullname[offset:].lstrip('/')) + _walk(path) + results.sort() + return results + + +class DictLoader(BaseLoader): + """Loads a template from a python dict. It's passed a dict of unicode + strings bound to template names. This loader is useful for unittesting: + + >>> loader = DictLoader({'index.html': 'source here'}) + + Because auto reloading is rarely useful this is disabled per default. + """ + + def __init__(self, mapping): + self.mapping = mapping + + def get_source(self, environment, template): + if template in self.mapping: + source = self.mapping[template] + return source, None, lambda: source == self.mapping.get(template) + raise TemplateNotFound(template) + + def list_templates(self): + return sorted(self.mapping) + + +class FunctionLoader(BaseLoader): + """A loader that is passed a function which does the loading. The + function receives the name of the template and has to return either + an unicode string with the template source, a tuple in the form ``(source, + filename, uptodatefunc)`` or `None` if the template does not exist. + + >>> def load_template(name): + ... if name == 'index.html': + ... return '...' + ... + >>> loader = FunctionLoader(load_template) + + The `uptodatefunc` is a function that is called if autoreload is enabled + and has to return `True` if the template is still up to date. For more + details have a look at :meth:`BaseLoader.get_source` which has the same + return value. + """ + + def __init__(self, load_func): + self.load_func = load_func + + def get_source(self, environment, template): + rv = self.load_func(template) + if rv is None: + raise TemplateNotFound(template) + elif isinstance(rv, string_types): + return rv, None, None + return rv + + +class PrefixLoader(BaseLoader): + """A loader that is passed a dict of loaders where each loader is bound + to a prefix. The prefix is delimited from the template by a slash per + default, which can be changed by setting the `delimiter` argument to + something else:: + + loader = PrefixLoader({ + 'app1': PackageLoader('mypackage.app1'), + 'app2': PackageLoader('mypackage.app2') + }) + + By loading ``'app1/index.html'`` the file from the app1 package is loaded, + by loading ``'app2/index.html'`` the file from the second. + """ + + def __init__(self, mapping, delimiter='/'): + self.mapping = mapping + self.delimiter = delimiter + + def get_loader(self, template): + try: + prefix, name = template.split(self.delimiter, 1) + loader = self.mapping[prefix] + except (ValueError, KeyError): + raise TemplateNotFound(template) + return loader, name + + def get_source(self, environment, template): + loader, name = self.get_loader(template) + try: + return loader.get_source(environment, name) + except TemplateNotFound: + # re-raise the exception with the correct filename here. + # (the one that includes the prefix) + raise TemplateNotFound(template) + + @internalcode + def load(self, environment, name, globals=None): + loader, local_name = self.get_loader(name) + try: + return loader.load(environment, local_name, globals) + except TemplateNotFound: + # re-raise the exception with the correct filename here. + # (the one that includes the prefix) + raise TemplateNotFound(name) + + def list_templates(self): + result = [] + for prefix, loader in iteritems(self.mapping): + for template in loader.list_templates(): + result.append(prefix + self.delimiter + template) + return result + + +class ChoiceLoader(BaseLoader): + """This loader works like the `PrefixLoader` just that no prefix is + specified. If a template could not be found by one loader the next one + is tried. + + >>> loader = ChoiceLoader([ + ... FileSystemLoader('/path/to/user/templates'), + ... FileSystemLoader('/path/to/system/templates') + ... ]) + + This is useful if you want to allow users to override builtin templates + from a different location. + """ + + def __init__(self, loaders): + self.loaders = loaders + + def get_source(self, environment, template): + for loader in self.loaders: + try: + return loader.get_source(environment, template) + except TemplateNotFound: + pass + raise TemplateNotFound(template) + + @internalcode + def load(self, environment, name, globals=None): + for loader in self.loaders: + try: + return loader.load(environment, name, globals) + except TemplateNotFound: + pass + raise TemplateNotFound(name) + + def list_templates(self): + found = set() + for loader in self.loaders: + found.update(loader.list_templates()) + return sorted(found) + + +class _TemplateModule(ModuleType): + """Like a normal module but with support for weak references""" + + +class ModuleLoader(BaseLoader): + """This loader loads templates from precompiled templates. + + Example usage: + + >>> loader = ChoiceLoader([ + ... ModuleLoader('/path/to/compiled/templates'), + ... FileSystemLoader('/path/to/templates') + ... ]) + + Templates can be precompiled with :meth:`Environment.compile_templates`. + """ + + has_source_access = False + + def __init__(self, path): + package_name = '_jinja2_module_templates_%x' % id(self) + + # create a fake module that looks for the templates in the + # path given. + mod = _TemplateModule(package_name) + if isinstance(path, string_types): + path = [path] + else: + path = list(path) + mod.__path__ = path + + sys.modules[package_name] = weakref.proxy(mod, + lambda x: sys.modules.pop(package_name, None)) + + # the only strong reference, the sys.modules entry is weak + # so that the garbage collector can remove it once the + # loader that created it goes out of business. + self.module = mod + self.package_name = package_name + + @staticmethod + def get_template_key(name): + return 'tmpl_' + sha1(name.encode('utf-8')).hexdigest() + + @staticmethod + def get_module_filename(name): + return ModuleLoader.get_template_key(name) + '.py' + + @internalcode + def load(self, environment, name, globals=None): + key = self.get_template_key(name) + module = '%s.%s' % (self.package_name, key) + mod = getattr(self.module, module, None) + if mod is None: + try: + mod = __import__(module, None, None, ['root']) + except ImportError: + raise TemplateNotFound(name) + + # remove the entry from sys.modules, we only want the attribute + # on the module object we have stored on the loader. + sys.modules.pop(module, None) + + return environment.template_class.from_module_dict( + environment, mod.__dict__, globals) |