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Diffstat (limited to 'src/jinja2/environment.py')
| -rw-r--r-- | src/jinja2/environment.py | 1331 |
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diff --git a/src/jinja2/environment.py b/src/jinja2/environment.py new file mode 100644 index 00000000..556f7255 --- /dev/null +++ b/src/jinja2/environment.py @@ -0,0 +1,1331 @@ +"""Classes for managing templates and their runtime and compile time +options. +""" +import os +import sys +import weakref +from functools import partial +from functools import reduce + +from markupsafe import Markup + +from . import nodes +from .compiler import CodeGenerator +from .compiler import generate +from .defaults import BLOCK_END_STRING +from .defaults import BLOCK_START_STRING +from .defaults import COMMENT_END_STRING +from .defaults import COMMENT_START_STRING +from .defaults import DEFAULT_FILTERS +from .defaults import DEFAULT_NAMESPACE +from .defaults import DEFAULT_POLICIES +from .defaults import DEFAULT_TESTS +from .defaults import KEEP_TRAILING_NEWLINE +from .defaults import LINE_COMMENT_PREFIX +from .defaults import LINE_STATEMENT_PREFIX +from .defaults import LSTRIP_BLOCKS +from .defaults import NEWLINE_SEQUENCE +from .defaults import TRIM_BLOCKS +from .defaults import VARIABLE_END_STRING +from .defaults import VARIABLE_START_STRING +from .exceptions import TemplateNotFound +from .exceptions import TemplateRuntimeError +from .exceptions import TemplatesNotFound +from .exceptions import TemplateSyntaxError +from .exceptions import UndefinedError +from .lexer import get_lexer +from .lexer import TokenStream +from .nodes import EvalContext +from .parser import Parser +from .runtime import Context +from .runtime import new_context +from .runtime import Undefined +from .utils import concat +from .utils import consume +from .utils import have_async_gen +from .utils import import_string +from .utils import internalcode +from .utils import LRUCache +from .utils import missing + +# for direct template usage we have up to ten living environments +_spontaneous_environments = LRUCache(10) + + +def get_spontaneous_environment(cls, *args): + """Return a new spontaneous environment. A spontaneous environment + is used for templates created directly rather than through an + existing environment. + + :param cls: Environment class to create. + :param args: Positional arguments passed to environment. + """ + key = (cls, args) + + try: + return _spontaneous_environments[key] + except KeyError: + _spontaneous_environments[key] = env = cls(*args) + env.shared = True + return env + + +def create_cache(size): + """Return the cache class for the given size.""" + if size == 0: + return None + if size < 0: + return {} + return LRUCache(size) + + +def copy_cache(cache): + """Create an empty copy of the given cache.""" + if cache is None: + return None + elif type(cache) is dict: + return {} + return LRUCache(cache.capacity) + + +def load_extensions(environment, extensions): + """Load the extensions from the list and bind it to the environment. + Returns a dict of instantiated environments. + """ + result = {} + for extension in extensions: + if isinstance(extension, str): + extension = import_string(extension) + result[extension.identifier] = extension(environment) + return result + + +def fail_for_missing_callable(thing, name): + msg = f"no {thing} named {name!r}" + + if isinstance(name, Undefined): + try: + name._fail_with_undefined_error() + except Exception as e: + msg = f"{msg} ({e}; did you forget to quote the callable name?)" + raise TemplateRuntimeError(msg) + + +def _environment_sanity_check(environment): + """Perform a sanity check on the environment.""" + assert issubclass( + environment.undefined, Undefined + ), "undefined must be a subclass of undefined because filters depend on it." + assert ( + environment.block_start_string + != environment.variable_start_string + != environment.comment_start_string + ), "block, variable and comment start strings must be different" + assert environment.newline_sequence in { + "\r", + "\r\n", + "\n", + }, "newline_sequence set to unknown line ending string." + return environment + + +class Environment: + r"""The core component of Jinja is the `Environment`. It contains + important shared variables like configuration, filters, tests, + globals and others. Instances of this class may be modified if + they are not shared and if no template was loaded so far. + Modifications on environments after the first template was loaded + will lead to surprising effects and undefined behavior. + + Here are the possible initialization parameters: + + `block_start_string` + The string marking the beginning of a block. Defaults to ``'{%'``. + + `block_end_string` + The string marking the end of a block. Defaults to ``'%}'``. + + `variable_start_string` + The string marking the beginning of a print statement. + Defaults to ``'{{'``. + + `variable_end_string` + The string marking the end of a print statement. Defaults to + ``'}}'``. + + `comment_start_string` + The string marking the beginning of a comment. Defaults to ``'{#'``. + + `comment_end_string` + The string marking the end of a comment. Defaults to ``'#}'``. + + `line_statement_prefix` + If given and a string, this will be used as prefix for line based + statements. See also :ref:`line-statements`. + + `line_comment_prefix` + If given and a string, this will be used as prefix for line based + comments. See also :ref:`line-statements`. + + .. versionadded:: 2.2 + + `trim_blocks` + If this is set to ``True`` the first newline after a block is + removed (block, not variable tag!). Defaults to `False`. + + `lstrip_blocks` + If this is set to ``True`` leading spaces and tabs are stripped + from the start of a line to a block. Defaults to `False`. + + `newline_sequence` + The sequence that starts a newline. Must be one of ``'\r'``, + ``'\n'`` or ``'\r\n'``. The default is ``'\n'`` which is a + useful default for Linux and OS X systems as well as web + applications. + + `keep_trailing_newline` + Preserve the trailing newline when rendering templates. + The default is ``False``, which causes a single newline, + if present, to be stripped from the end of the template. + + .. versionadded:: 2.7 + + `extensions` + List of Jinja extensions to use. This can either be import paths + as strings or extension classes. For more information have a + look at :ref:`the extensions documentation <jinja-extensions>`. + + `optimized` + should the optimizer be enabled? Default is ``True``. + + `undefined` + :class:`Undefined` or a subclass of it that is used to represent + undefined values in the template. + + `finalize` + A callable that can be used to process the result of a variable + expression before it is output. For example one can convert + ``None`` implicitly into an empty string here. + + `autoescape` + If set to ``True`` the XML/HTML autoescaping feature is enabled by + default. For more details about autoescaping see + :class:`~markupsafe.Markup`. As of Jinja 2.4 this can also + be a callable that is passed the template name and has to + return ``True`` or ``False`` depending on autoescape should be + enabled by default. + + .. versionchanged:: 2.4 + `autoescape` can now be a function + + `loader` + The template loader for this environment. + + `cache_size` + The size of the cache. Per default this is ``400`` which means + that if more than 400 templates are loaded the loader will clean + out the least recently used template. If the cache size is set to + ``0`` templates are recompiled all the time, if the cache size is + ``-1`` the cache will not be cleaned. + + .. versionchanged:: 2.8 + The cache size was increased to 400 from a low 50. + + `auto_reload` + Some loaders load templates from locations where the template + sources may change (ie: file system or database). If + ``auto_reload`` is set to ``True`` (default) every time a template is + requested the loader checks if the source changed and if yes, it + will reload the template. For higher performance it's possible to + disable that. + + `bytecode_cache` + If set to a bytecode cache object, this object will provide a + cache for the internal Jinja bytecode so that templates don't + have to be parsed if they were not changed. + + See :ref:`bytecode-cache` for more information. + + `enable_async` + If set to true this enables async template execution which + allows using async functions and generators. + """ + + #: if this environment is sandboxed. Modifying this variable won't make + #: the environment sandboxed though. For a real sandboxed environment + #: have a look at jinja2.sandbox. This flag alone controls the code + #: generation by the compiler. + sandboxed = False + + #: True if the environment is just an overlay + overlayed = False + + #: the environment this environment is linked to if it is an overlay + linked_to = None + + #: shared environments have this set to `True`. A shared environment + #: must not be modified + shared = False + + #: the class that is used for code generation. See + #: :class:`~jinja2.compiler.CodeGenerator` for more information. + code_generator_class = CodeGenerator + + #: the context class thatis used for templates. See + #: :class:`~jinja2.runtime.Context` for more information. + context_class = Context + + def __init__( + self, + block_start_string=BLOCK_START_STRING, + block_end_string=BLOCK_END_STRING, + variable_start_string=VARIABLE_START_STRING, + variable_end_string=VARIABLE_END_STRING, + comment_start_string=COMMENT_START_STRING, + comment_end_string=COMMENT_END_STRING, + line_statement_prefix=LINE_STATEMENT_PREFIX, + line_comment_prefix=LINE_COMMENT_PREFIX, + trim_blocks=TRIM_BLOCKS, + lstrip_blocks=LSTRIP_BLOCKS, + newline_sequence=NEWLINE_SEQUENCE, + keep_trailing_newline=KEEP_TRAILING_NEWLINE, + extensions=(), + optimized=True, + undefined=Undefined, + finalize=None, + autoescape=False, + loader=None, + cache_size=400, + auto_reload=True, + bytecode_cache=None, + enable_async=False, + ): + # !!Important notice!! + # The constructor accepts quite a few arguments that should be + # passed by keyword rather than position. However it's important to + # not change the order of arguments because it's used at least + # internally in those cases: + # - spontaneous environments (i18n extension and Template) + # - unittests + # If parameter changes are required only add parameters at the end + # and don't change the arguments (or the defaults!) of the arguments + # existing already. + + # lexer / parser information + self.block_start_string = block_start_string + self.block_end_string = block_end_string + self.variable_start_string = variable_start_string + self.variable_end_string = variable_end_string + self.comment_start_string = comment_start_string + self.comment_end_string = comment_end_string + self.line_statement_prefix = line_statement_prefix + self.line_comment_prefix = line_comment_prefix + self.trim_blocks = trim_blocks + self.lstrip_blocks = lstrip_blocks + self.newline_sequence = newline_sequence + self.keep_trailing_newline = keep_trailing_newline + + # runtime information + self.undefined = undefined + self.optimized = optimized + self.finalize = finalize + self.autoescape = autoescape + + # defaults + self.filters = DEFAULT_FILTERS.copy() + self.tests = DEFAULT_TESTS.copy() + self.globals = DEFAULT_NAMESPACE.copy() + + # set the loader provided + self.loader = loader + self.cache = create_cache(cache_size) + self.bytecode_cache = bytecode_cache + self.auto_reload = auto_reload + + # configurable policies + self.policies = DEFAULT_POLICIES.copy() + + # load extensions + self.extensions = load_extensions(self, extensions) + + self.enable_async = enable_async + self.is_async = self.enable_async and have_async_gen + if self.is_async: + # runs patch_all() to enable async support + from . import asyncsupport # noqa: F401 + + _environment_sanity_check(self) + + def add_extension(self, extension): + """Adds an extension after the environment was created. + + .. versionadded:: 2.5 + """ + self.extensions.update(load_extensions(self, [extension])) + + def extend(self, **attributes): + """Add the items to the instance of the environment if they do not exist + yet. This is used by :ref:`extensions <writing-extensions>` to register + callbacks and configuration values without breaking inheritance. + """ + for key, value in attributes.items(): + if not hasattr(self, key): + setattr(self, key, value) + + def overlay( + self, + block_start_string=missing, + block_end_string=missing, + variable_start_string=missing, + variable_end_string=missing, + comment_start_string=missing, + comment_end_string=missing, + line_statement_prefix=missing, + line_comment_prefix=missing, + trim_blocks=missing, + lstrip_blocks=missing, + extensions=missing, + optimized=missing, + undefined=missing, + finalize=missing, + autoescape=missing, + loader=missing, + cache_size=missing, + auto_reload=missing, + bytecode_cache=missing, + ): + """Create a new overlay environment that shares all the data with the + current environment except for cache and the overridden attributes. + Extensions cannot be removed for an overlayed environment. An overlayed + environment automatically gets all the extensions of the environment it + is linked to plus optional extra extensions. + + Creating overlays should happen after the initial environment was set + up completely. Not all attributes are truly linked, some are just + copied over so modifications on the original environment may not shine + through. + """ + args = dict(locals()) + del args["self"], args["cache_size"], args["extensions"] + + rv = object.__new__(self.__class__) + rv.__dict__.update(self.__dict__) + rv.overlayed = True + rv.linked_to = self + + for key, value in args.items(): + if value is not missing: + setattr(rv, key, value) + + if cache_size is not missing: + rv.cache = create_cache(cache_size) + else: + rv.cache = copy_cache(self.cache) + + rv.extensions = {} + for key, value in self.extensions.items(): + rv.extensions[key] = value.bind(rv) + if extensions is not missing: + rv.extensions.update(load_extensions(rv, extensions)) + + return _environment_sanity_check(rv) + + lexer = property(get_lexer, doc="The lexer for this environment.") + + def iter_extensions(self): + """Iterates over the extensions by priority.""" + return iter(sorted(self.extensions.values(), key=lambda x: x.priority)) + + def getitem(self, obj, argument): + """Get an item or attribute of an object but prefer the item.""" + try: + return obj[argument] + except (AttributeError, TypeError, LookupError): + if isinstance(argument, str): + try: + attr = str(argument) + except Exception: + pass + else: + try: + return getattr(obj, attr) + except AttributeError: + pass + return self.undefined(obj=obj, name=argument) + + def getattr(self, obj, attribute): + """Get an item or attribute of an object but prefer the attribute. + Unlike :meth:`getitem` the attribute *must* be a bytestring. + """ + try: + return getattr(obj, attribute) + except AttributeError: + pass + try: + return obj[attribute] + except (TypeError, LookupError, AttributeError): + return self.undefined(obj=obj, name=attribute) + + def call_filter( + self, name, value, args=None, kwargs=None, context=None, eval_ctx=None + ): + """Invokes a filter on a value the same way the compiler does. + + This might return a coroutine if the filter is running from an + environment in async mode and the filter supports async + execution. It's your responsibility to await this if needed. + + .. versionadded:: 2.7 + """ + func = self.filters.get(name) + if func is None: + fail_for_missing_callable("filter", name) + args = [value] + list(args or ()) + if getattr(func, "contextfilter", False) is True: + if context is None: + raise TemplateRuntimeError( + "Attempted to invoke context filter without context" + ) + args.insert(0, context) + elif getattr(func, "evalcontextfilter", False) is True: + if eval_ctx is None: + if context is not None: + eval_ctx = context.eval_ctx + else: + eval_ctx = EvalContext(self) + args.insert(0, eval_ctx) + elif getattr(func, "environmentfilter", False) is True: + args.insert(0, self) + return func(*args, **(kwargs or {})) + + def call_test(self, name, value, args=None, kwargs=None): + """Invokes a test on a value the same way the compiler does it. + + .. versionadded:: 2.7 + """ + func = self.tests.get(name) + if func is None: + fail_for_missing_callable("test", name) + return func(value, *(args or ()), **(kwargs or {})) + + @internalcode + def parse(self, source, name=None, filename=None): + """Parse the sourcecode and return the abstract syntax tree. This + tree of nodes is used by the compiler to convert the template into + executable source- or bytecode. This is useful for debugging or to + extract information from templates. + + If you are :ref:`developing Jinja extensions <writing-extensions>` + this gives you a good overview of the node tree generated. + """ + try: + return self._parse(source, name, filename) + except TemplateSyntaxError: + self.handle_exception(source=source) + + def _parse(self, source, name, filename): + """Internal parsing function used by `parse` and `compile`.""" + return Parser(self, source, name, filename).parse() + + def lex(self, source, name=None, filename=None): + """Lex the given sourcecode and return a generator that yields + tokens as tuples in the form ``(lineno, token_type, value)``. + This can be useful for :ref:`extension development <writing-extensions>` + and debugging templates. + + This does not perform preprocessing. If you want the preprocessing + of the extensions to be applied you have to filter source through + the :meth:`preprocess` method. + """ + source = str(source) + try: + return self.lexer.tokeniter(source, name, filename) + except TemplateSyntaxError: + self.handle_exception(source=source) + + def preprocess(self, source, name=None, filename=None): + """Preprocesses the source with all extensions. This is automatically + called for all parsing and compiling methods but *not* for :meth:`lex` + because there you usually only want the actual source tokenized. + """ + return reduce( + lambda s, e: e.preprocess(s, name, filename), + self.iter_extensions(), + str(source), + ) + + def _tokenize(self, source, name, filename=None, state=None): + """Called by the parser to do the preprocessing and filtering + for all the extensions. Returns a :class:`~jinja2.lexer.TokenStream`. + """ + source = self.preprocess(source, name, filename) + stream = self.lexer.tokenize(source, name, filename, state) + for ext in self.iter_extensions(): + stream = ext.filter_stream(stream) + if not isinstance(stream, TokenStream): + stream = TokenStream(stream, name, filename) + return stream + + def _generate(self, source, name, filename, defer_init=False): + """Internal hook that can be overridden to hook a different generate + method in. + + .. versionadded:: 2.5 + """ + return generate( + source, + self, + name, + filename, + defer_init=defer_init, + optimized=self.optimized, + ) + + def _compile(self, source, filename): + """Internal hook that can be overridden to hook a different compile + method in. + + .. versionadded:: 2.5 + """ + return compile(source, filename, "exec") + + @internalcode + def compile(self, source, name=None, filename=None, raw=False, defer_init=False): + """Compile a node or template source code. The `name` parameter is + the load name of the template after it was joined using + :meth:`join_path` if necessary, not the filename on the file system. + the `filename` parameter is the estimated filename of the template on + the file system. If the template came from a database or memory this + can be omitted. + + The return value of this method is a python code object. If the `raw` + parameter is `True` the return value will be a string with python + code equivalent to the bytecode returned otherwise. This method is + mainly used internally. + + `defer_init` is use internally to aid the module code generator. This + causes the generated code to be able to import without the global + environment variable to be set. + + .. versionadded:: 2.4 + `defer_init` parameter added. + """ + source_hint = None + try: + if isinstance(source, str): + source_hint = source + source = self._parse(source, name, filename) + source = self._generate(source, name, filename, defer_init=defer_init) + if raw: + return source + if filename is None: + filename = "<template>" + return self._compile(source, filename) + except TemplateSyntaxError: + self.handle_exception(source=source_hint) + + def compile_expression(self, source, undefined_to_none=True): + """A handy helper method that returns a callable that accepts keyword + arguments that appear as variables in the expression. If called it + returns the result of the expression. + + This is useful if applications want to use the same rules as Jinja + in template "configuration files" or similar situations. + + Example usage: + + >>> env = Environment() + >>> expr = env.compile_expression('foo == 42') + >>> expr(foo=23) + False + >>> expr(foo=42) + True + + Per default the return value is converted to `None` if the + expression returns an undefined value. This can be changed + by setting `undefined_to_none` to `False`. + + >>> env.compile_expression('var')() is None + True + >>> env.compile_expression('var', undefined_to_none=False)() + Undefined + + .. versionadded:: 2.1 + """ + parser = Parser(self, source, state="variable") + try: + expr = parser.parse_expression() + if not parser.stream.eos: + raise TemplateSyntaxError( + "chunk after expression", parser.stream.current.lineno, None, None + ) + expr.set_environment(self) + except TemplateSyntaxError: + if sys.exc_info() is not None: + self.handle_exception(source=source) + + body = [nodes.Assign(nodes.Name("result", "store"), expr, lineno=1)] + template = self.from_string(nodes.Template(body, lineno=1)) + return TemplateExpression(template, undefined_to_none) + + def compile_templates( + self, + target, + extensions=None, + filter_func=None, + zip="deflated", + log_function=None, + ignore_errors=True, + ): + """Finds all the templates the loader can find, compiles them + and stores them in `target`. If `zip` is `None`, instead of in a + zipfile, the templates will be stored in a directory. + By default a deflate zip algorithm is used. To switch to + the stored algorithm, `zip` can be set to ``'stored'``. + + `extensions` and `filter_func` are passed to :meth:`list_templates`. + Each template returned will be compiled to the target folder or + zipfile. + + By default template compilation errors are ignored. In case a + log function is provided, errors are logged. If you want template + syntax errors to abort the compilation you can set `ignore_errors` + to `False` and you will get an exception on syntax errors. + + .. versionadded:: 2.4 + """ + from .loaders import ModuleLoader + + if log_function is None: + + def log_function(x): + pass + + def write_file(filename, data): + if zip: + info = ZipInfo(filename) + info.external_attr = 0o755 << 16 + zip_file.writestr(info, data) + else: + if isinstance(data, str): + data = data.encode("utf8") + + with open(os.path.join(target, filename), "wb") as f: + f.write(data) + + if zip is not None: + from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED + + zip_file = ZipFile( + target, "w", dict(deflated=ZIP_DEFLATED, stored=ZIP_STORED)[zip] + ) + log_function(f"Compiling into Zip archive {target!r}") + else: + if not os.path.isdir(target): + os.makedirs(target) + log_function(f"Compiling into folder {target!r}") + + try: + for name in self.list_templates(extensions, filter_func): + source, filename, _ = self.loader.get_source(self, name) + try: + code = self.compile(source, name, filename, True, True) + except TemplateSyntaxError as e: + if not ignore_errors: + raise + log_function(f'Could not compile "{name}": {e}') + continue + + filename = ModuleLoader.get_module_filename(name) + + write_file(filename, code) + log_function(f'Compiled "{name}" as {filename}') + finally: + if zip: + zip_file.close() + + log_function("Finished compiling templates") + + def list_templates(self, extensions=None, filter_func=None): + """Returns a list of templates for this environment. This requires + that the loader supports the loader's + :meth:`~BaseLoader.list_templates` method. + + If there are other files in the template folder besides the + actual templates, the returned list can be filtered. There are two + ways: either `extensions` is set to a list of file extensions for + templates, or a `filter_func` can be provided which is a callable that + is passed a template name and should return `True` if it should end up + in the result list. + + If the loader does not support that, a :exc:`TypeError` is raised. + + .. versionadded:: 2.4 + """ + names = self.loader.list_templates() + + if extensions is not None: + if filter_func is not None: + raise TypeError( + "either extensions or filter_func can be passed, but not both" + ) + + def filter_func(x): + return "." in x and x.rsplit(".", 1)[1] in extensions + + if filter_func is not None: + names = [name for name in names if filter_func(name)] + + return names + + def handle_exception(self, source=None): + """Exception handling helper. This is used internally to either raise + rewritten exceptions or return a rendered traceback for the template. + """ + from .debug import rewrite_traceback_stack + + raise rewrite_traceback_stack(source=source) + + def join_path(self, template, parent): + """Join a template with the parent. By default all the lookups are + relative to the loader root so this method returns the `template` + parameter unchanged, but if the paths should be relative to the + parent template, this function can be used to calculate the real + template name. + + Subclasses may override this method and implement template path + joining here. + """ + return template + + @internalcode + def _load_template(self, name, globals): + if self.loader is None: + raise TypeError("no loader for this environment specified") + cache_key = (weakref.ref(self.loader), name) + if self.cache is not None: + template = self.cache.get(cache_key) + if template is not None and ( + not self.auto_reload or template.is_up_to_date + ): + return template + template = self.loader.load(self, name, globals) + if self.cache is not None: + self.cache[cache_key] = template + return template + + @internalcode + def get_template(self, name, parent=None, globals=None): + """Load a template from the loader. If a loader is configured this + method asks the loader for the template and returns a :class:`Template`. + If the `parent` parameter is not `None`, :meth:`join_path` is called + to get the real template name before loading. + + The `globals` parameter can be used to provide template wide globals. + These variables are available in the context at render time. + + If the template does not exist a :exc:`TemplateNotFound` exception is + raised. + + .. versionchanged:: 2.4 + If `name` is a :class:`Template` object it is returned from the + function unchanged. + """ + if isinstance(name, Template): + return name + if parent is not None: + name = self.join_path(name, parent) + return self._load_template(name, self.make_globals(globals)) + + @internalcode + def select_template(self, names, parent=None, globals=None): + """Works like :meth:`get_template` but tries a number of templates + before it fails. If it cannot find any of the templates, it will + raise a :exc:`TemplatesNotFound` exception. + + .. versionchanged:: 2.11 + If names is :class:`Undefined`, an :exc:`UndefinedError` is + raised instead. If no templates were found and names + contains :class:`Undefined`, the message is more helpful. + + .. versionchanged:: 2.4 + If `names` contains a :class:`Template` object it is returned + from the function unchanged. + + .. versionadded:: 2.3 + """ + if isinstance(names, Undefined): + names._fail_with_undefined_error() + + if not names: + raise TemplatesNotFound( + message="Tried to select from an empty list of templates." + ) + globals = self.make_globals(globals) + for name in names: + if isinstance(name, Template): + return name + if parent is not None: + name = self.join_path(name, parent) + try: + return self._load_template(name, globals) + except (TemplateNotFound, UndefinedError): + pass + raise TemplatesNotFound(names) + + @internalcode + def get_or_select_template(self, template_name_or_list, parent=None, globals=None): + """Does a typecheck and dispatches to :meth:`select_template` + if an iterable of template names is given, otherwise to + :meth:`get_template`. + + .. versionadded:: 2.3 + """ + if isinstance(template_name_or_list, (str, Undefined)): + return self.get_template(template_name_or_list, parent, globals) + elif isinstance(template_name_or_list, Template): + return template_name_or_list + return self.select_template(template_name_or_list, parent, globals) + + def from_string(self, source, globals=None, template_class=None): + """Load a template from a string. This parses the source given and + returns a :class:`Template` object. + """ + globals = self.make_globals(globals) + cls = template_class or self.template_class + return cls.from_code(self, self.compile(source), globals, None) + + def make_globals(self, d): + """Return a dict for the globals.""" + if not d: + return self.globals + return dict(self.globals, **d) + + +class Template: + """The central template object. This class represents a compiled template + and is used to evaluate it. + + Normally the template object is generated from an :class:`Environment` but + it also has a constructor that makes it possible to create a template + instance directly using the constructor. It takes the same arguments as + the environment constructor but it's not possible to specify a loader. + + Every template object has a few methods and members that are guaranteed + to exist. However it's important that a template object should be + considered immutable. Modifications on the object are not supported. + + Template objects created from the constructor rather than an environment + do have an `environment` attribute that points to a temporary environment + that is probably shared with other templates created with the constructor + and compatible settings. + + >>> template = Template('Hello {{ name }}!') + >>> template.render(name='John Doe') == u'Hello John Doe!' + True + >>> stream = template.stream(name='John Doe') + >>> next(stream) == u'Hello John Doe!' + True + >>> next(stream) + Traceback (most recent call last): + ... + StopIteration + """ + + #: Type of environment to create when creating a template directly + #: rather than through an existing environment. + environment_class = Environment + + def __new__( + cls, + source, + block_start_string=BLOCK_START_STRING, + block_end_string=BLOCK_END_STRING, + variable_start_string=VARIABLE_START_STRING, + variable_end_string=VARIABLE_END_STRING, + comment_start_string=COMMENT_START_STRING, + comment_end_string=COMMENT_END_STRING, + line_statement_prefix=LINE_STATEMENT_PREFIX, + line_comment_prefix=LINE_COMMENT_PREFIX, + trim_blocks=TRIM_BLOCKS, + lstrip_blocks=LSTRIP_BLOCKS, + newline_sequence=NEWLINE_SEQUENCE, + keep_trailing_newline=KEEP_TRAILING_NEWLINE, + extensions=(), + optimized=True, + undefined=Undefined, + finalize=None, + autoescape=False, + enable_async=False, + ): + env = get_spontaneous_environment( + cls.environment_class, + block_start_string, + block_end_string, + variable_start_string, + variable_end_string, + comment_start_string, + comment_end_string, + line_statement_prefix, + line_comment_prefix, + trim_blocks, + lstrip_blocks, + newline_sequence, + keep_trailing_newline, + frozenset(extensions), + optimized, + undefined, + finalize, + autoescape, + None, + 0, + False, + None, + enable_async, + ) + return env.from_string(source, template_class=cls) + + @classmethod + def from_code(cls, environment, code, globals, uptodate=None): + """Creates a template object from compiled code and the globals. This + is used by the loaders and environment to create a template object. + """ + namespace = {"environment": environment, "__file__": code.co_filename} + exec(code, namespace) + rv = cls._from_namespace(environment, namespace, globals) + rv._uptodate = uptodate + return rv + + @classmethod + def from_module_dict(cls, environment, module_dict, globals): + """Creates a template object from a module. This is used by the + module loader to create a template object. + + .. versionadded:: 2.4 + """ + return cls._from_namespace(environment, module_dict, globals) + + @classmethod + def _from_namespace(cls, environment, namespace, globals): + t = object.__new__(cls) + t.environment = environment + t.globals = globals + t.name = namespace["name"] + t.filename = namespace["__file__"] + t.blocks = namespace["blocks"] + + # render function and module + t.root_render_func = namespace["root"] + t._module = None + + # debug and loader helpers + t._debug_info = namespace["debug_info"] + t._uptodate = None + + # store the reference + namespace["environment"] = environment + namespace["__jinja_template__"] = t + + return t + + def render(self, *args, **kwargs): + """This method accepts the same arguments as the `dict` constructor: + A dict, a dict subclass or some keyword arguments. If no arguments + are given the context will be empty. These two calls do the same:: + + template.render(knights='that say nih') + template.render({'knights': 'that say nih'}) + + This will return the rendered template as a string. + """ + vars = dict(*args, **kwargs) + try: + return concat(self.root_render_func(self.new_context(vars))) + except Exception: + self.environment.handle_exception() + + def render_async(self, *args, **kwargs): + """This works similar to :meth:`render` but returns a coroutine + that when awaited returns the entire rendered template string. This + requires the async feature to be enabled. + + Example usage:: + + await template.render_async(knights='that say nih; asynchronously') + """ + # see asyncsupport for the actual implementation + raise NotImplementedError( + "This feature is not available for this version of Python" + ) + + def stream(self, *args, **kwargs): + """Works exactly like :meth:`generate` but returns a + :class:`TemplateStream`. + """ + return TemplateStream(self.generate(*args, **kwargs)) + + def generate(self, *args, **kwargs): + """For very large templates it can be useful to not render the whole + template at once but evaluate each statement after another and yield + piece for piece. This method basically does exactly that and returns + a generator that yields one item after another as strings. + + It accepts the same arguments as :meth:`render`. + """ + vars = dict(*args, **kwargs) + try: + yield from self.root_render_func(self.new_context(vars)) + except Exception: + yield self.environment.handle_exception() + + def generate_async(self, *args, **kwargs): + """An async version of :meth:`generate`. Works very similarly but + returns an async iterator instead. + """ + # see asyncsupport for the actual implementation + raise NotImplementedError( + "This feature is not available for this version of Python" + ) + + def new_context(self, vars=None, shared=False, locals=None): + """Create a new :class:`Context` for this template. The vars + provided will be passed to the template. Per default the globals + are added to the context. If shared is set to `True` the data + is passed as is to the context without adding the globals. + + `locals` can be a dict of local variables for internal usage. + """ + return new_context( + self.environment, self.name, self.blocks, vars, shared, self.globals, locals + ) + + def make_module(self, vars=None, shared=False, locals=None): + """This method works like the :attr:`module` attribute when called + without arguments but it will evaluate the template on every call + rather than caching it. It's also possible to provide + a dict which is then used as context. The arguments are the same + as for the :meth:`new_context` method. + """ + return TemplateModule(self, self.new_context(vars, shared, locals)) + + def make_module_async(self, vars=None, shared=False, locals=None): + """As template module creation can invoke template code for + asynchronous executions this method must be used instead of the + normal :meth:`make_module` one. Likewise the module attribute + becomes unavailable in async mode. + """ + # see asyncsupport for the actual implementation + raise NotImplementedError( + "This feature is not available for this version of Python" + ) + + @internalcode + def _get_default_module(self, ctx=None): + """If a context is passed in, this means that the template was + imported. Imported templates have access to the current template's + globals by default, but they can only be accessed via the context + during runtime. + + If there are new globals, we need to create a new + module because the cached module is already rendered and will not have + access to globals from the current context. This new module is not + cached as :attr:`_module` because the template can be imported elsewhere, + and it should have access to only the current template's globals. + """ + if ctx is not None: + globals = { + key: ctx.parent[key] for key in ctx.globals_keys - self.globals.keys() + } + if globals: + return self.make_module(globals) + if self._module is not None: + return self._module + self._module = rv = self.make_module() + return rv + + @property + def module(self): + """The template as module. This is used for imports in the + template runtime but is also useful if one wants to access + exported template variables from the Python layer: + + >>> t = Template('{% macro foo() %}42{% endmacro %}23') + >>> str(t.module) + '23' + >>> t.module.foo() == u'42' + True + + This attribute is not available if async mode is enabled. + """ + return self._get_default_module() + + def get_corresponding_lineno(self, lineno): + """Return the source line number of a line number in the + generated bytecode as they are not in sync. + """ + for template_line, code_line in reversed(self.debug_info): + if code_line <= lineno: + return template_line + return 1 + + @property + def is_up_to_date(self): + """If this variable is `False` there is a newer version available.""" + if self._uptodate is None: + return True + return self._uptodate() + + @property + def debug_info(self): + """The debug info mapping.""" + if self._debug_info: + return [tuple(map(int, x.split("="))) for x in self._debug_info.split("&")] + return [] + + def __repr__(self): + if self.name is None: + name = f"memory:{id(self):x}" + else: + name = repr(self.name) + return f"<{self.__class__.__name__} {name}>" + + +class TemplateModule: + """Represents an imported template. All the exported names of the + template are available as attributes on this object. Additionally + converting it into a string renders the contents. + """ + + def __init__(self, template, context, body_stream=None): + if body_stream is None: + if context.environment.is_async: + raise RuntimeError( + "Async mode requires a body stream " + "to be passed to a template module. Use " + "the async methods of the API you are " + "using." + ) + body_stream = list(template.root_render_func(context)) + self._body_stream = body_stream + self.__dict__.update(context.get_exported()) + self.__name__ = template.name + + def __html__(self): + return Markup(concat(self._body_stream)) + + def __str__(self): + return concat(self._body_stream) + + def __repr__(self): + if self.__name__ is None: + name = f"memory:{id(self):x}" + else: + name = repr(self.__name__) + return f"<{self.__class__.__name__} {name}>" + + +class TemplateExpression: + """The :meth:`jinja2.Environment.compile_expression` method returns an + instance of this object. It encapsulates the expression-like access + to the template with an expression it wraps. + """ + + def __init__(self, template, undefined_to_none): + self._template = template + self._undefined_to_none = undefined_to_none + + def __call__(self, *args, **kwargs): + context = self._template.new_context(dict(*args, **kwargs)) + consume(self._template.root_render_func(context)) + rv = context.vars["result"] + if self._undefined_to_none and isinstance(rv, Undefined): + rv = None + return rv + + +class TemplateStream: + """A template stream works pretty much like an ordinary python generator + but it can buffer multiple items to reduce the number of total iterations. + Per default the output is unbuffered which means that for every unbuffered + instruction in the template one string is yielded. + + If buffering is enabled with a buffer size of 5, five items are combined + into a new string. This is mainly useful if you are streaming + big templates to a client via WSGI which flushes after each iteration. + """ + + def __init__(self, gen): + self._gen = gen + self.disable_buffering() + + def dump(self, fp, encoding=None, errors="strict"): + """Dump the complete stream into a file or file-like object. + Per default strings are written, if you want to encode + before writing specify an `encoding`. + + Example usage:: + + Template('Hello {{ name }}!').stream(name='foo').dump('hello.html') + """ + close = False + if isinstance(fp, str): + if encoding is None: + encoding = "utf-8" + fp = open(fp, "wb") + close = True + try: + if encoding is not None: + iterable = (x.encode(encoding, errors) for x in self) + else: + iterable = self + if hasattr(fp, "writelines"): + fp.writelines(iterable) + else: + for item in iterable: + fp.write(item) + finally: + if close: + fp.close() + + def disable_buffering(self): + """Disable the output buffering.""" + self._next = partial(next, self._gen) + self.buffered = False + + def _buffered_generator(self, size): + buf = [] + c_size = 0 + push = buf.append + + while 1: + try: + while c_size < size: + c = next(self._gen) + push(c) + if c: + c_size += 1 + except StopIteration: + if not c_size: + return + yield concat(buf) + del buf[:] + c_size = 0 + + def enable_buffering(self, size=5): + """Enable buffering. Buffer `size` items before yielding them.""" + if size <= 1: + raise ValueError("buffer size too small") + + self.buffered = True + self._next = partial(next, self._buffered_generator(size)) + + def __iter__(self): + return self + + def __next__(self): + return self._next() + + +# hook in default template class. if anyone reads this comment: ignore that +# it's possible to use custom templates ;-) +Environment.template_class = Template |