Загрузить файлы в «venv/Lib/site-packages/jinja2»

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2026-07-02 18:40:47 +00:00
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commit eab62ccbf6
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"""Functions that expose information about templates that might be
interesting for introspection.
"""
import typing as t
from . import nodes
from .compiler import CodeGenerator
from .compiler import Frame
if t.TYPE_CHECKING:
from .environment import Environment
class TrackingCodeGenerator(CodeGenerator):
"""We abuse the code generator for introspection."""
def __init__(self, environment: "Environment") -> None:
super().__init__(environment, "<introspection>", "<introspection>")
self.undeclared_identifiers: t.Set[str] = set()
def write(self, x: str) -> None:
"""Don't write."""
def enter_frame(self, frame: Frame) -> None:
"""Remember all undeclared identifiers."""
super().enter_frame(frame)
for _, (action, param) in frame.symbols.loads.items():
if action == "resolve" and param not in self.environment.globals:
self.undeclared_identifiers.add(param)
def find_undeclared_variables(ast: nodes.Template) -> t.Set[str]:
"""Returns a set of all variables in the AST that will be looked up from
the context at runtime. Because at compile time it's not known which
variables will be used depending on the path the execution takes at
runtime, all variables are returned.
>>> from jinja2 import Environment, meta
>>> env = Environment()
>>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
>>> meta.find_undeclared_variables(ast) == {'bar'}
True
.. admonition:: Implementation
Internally the code generator is used for finding undeclared variables.
This is good to know because the code generator might raise a
:exc:`TemplateAssertionError` during compilation and as a matter of
fact this function can currently raise that exception as well.
"""
codegen = TrackingCodeGenerator(ast.environment) # type: ignore
codegen.visit(ast)
return codegen.undeclared_identifiers
_ref_types = (nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include)
_RefType = t.Union[nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include]
def find_referenced_templates(ast: nodes.Template) -> t.Iterator[t.Optional[str]]:
"""Finds all the referenced templates from the AST. This will return an
iterator over all the hardcoded template extensions, inclusions and
imports. If dynamic inheritance or inclusion is used, `None` will be
yielded.
>>> from jinja2 import Environment, meta
>>> env = Environment()
>>> ast = env.parse('{% extends "layout.html" %}{% include helper %}')
>>> list(meta.find_referenced_templates(ast))
['layout.html', None]
This function is useful for dependency tracking. For example if you want
to rebuild parts of the website after a layout template has changed.
"""
template_name: t.Any
for node in ast.find_all(_ref_types):
template: nodes.Expr = node.template # type: ignore
if not isinstance(template, nodes.Const):
# a tuple with some non consts in there
if isinstance(template, (nodes.Tuple, nodes.List)):
for template_name in template.items:
# something const, only yield the strings and ignore
# non-string consts that really just make no sense
if isinstance(template_name, nodes.Const):
if isinstance(template_name.value, str):
yield template_name.value
# something dynamic in there
else:
yield None
# something dynamic we don't know about here
else:
yield None
continue
# constant is a basestring, direct template name
if isinstance(template.value, str):
yield template.value
# a tuple or list (latter *should* not happen) made of consts,
# yield the consts that are strings. We could warn here for
# non string values
elif isinstance(node, nodes.Include) and isinstance(
template.value, (tuple, list)
):
for template_name in template.value:
if isinstance(template_name, str):
yield template_name
# something else we don't care about, we could warn here
else:
yield None

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import typing as t
from ast import literal_eval
from ast import parse
from itertools import chain
from itertools import islice
from types import GeneratorType
from . import nodes
from .compiler import CodeGenerator
from .compiler import Frame
from .compiler import has_safe_repr
from .environment import Environment
from .environment import Template
def native_concat(values: t.Iterable[t.Any]) -> t.Optional[t.Any]:
"""Return a native Python type from the list of compiled nodes. If
the result is a single node, its value is returned. Otherwise, the
nodes are concatenated as strings. If the result can be parsed with
:func:`ast.literal_eval`, the parsed value is returned. Otherwise,
the string is returned.
:param values: Iterable of outputs to concatenate.
"""
head = list(islice(values, 2))
if not head:
return None
if len(head) == 1:
raw = head[0]
if not isinstance(raw, str):
return raw
else:
if isinstance(values, GeneratorType):
values = chain(head, values)
raw = "".join([str(v) for v in values])
try:
return literal_eval(
# In Python 3.10+ ast.literal_eval removes leading spaces/tabs
# from the given string. For backwards compatibility we need to
# parse the string ourselves without removing leading spaces/tabs.
parse(raw, mode="eval")
)
except (ValueError, SyntaxError, MemoryError):
return raw
class NativeCodeGenerator(CodeGenerator):
"""A code generator which renders Python types by not adding
``str()`` around output nodes.
"""
@staticmethod
def _default_finalize(value: t.Any) -> t.Any:
return value
def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
return repr("".join([str(v) for v in group]))
def _output_child_to_const(
self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
) -> t.Any:
const = node.as_const(frame.eval_ctx)
if not has_safe_repr(const):
raise nodes.Impossible()
if isinstance(node, nodes.TemplateData):
return const
return finalize.const(const) # type: ignore
def _output_child_pre(
self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
) -> None:
if finalize.src is not None:
self.write(finalize.src)
def _output_child_post(
self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
) -> None:
if finalize.src is not None:
self.write(")")
class NativeEnvironment(Environment):
"""An environment that renders templates to native Python types."""
code_generator_class = NativeCodeGenerator
concat = staticmethod(native_concat) # type: ignore
class NativeTemplate(Template):
environment_class = NativeEnvironment
def render(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
"""Render the template to produce a native Python type. If the
result is a single node, its value is returned. Otherwise, the
nodes are concatenated as strings. If the result can be parsed
with :func:`ast.literal_eval`, the parsed value is returned.
Otherwise, the string is returned.
"""
ctx = self.new_context(dict(*args, **kwargs))
try:
return self.environment_class.concat( # type: ignore
self.root_render_func(ctx)
)
except Exception:
return self.environment.handle_exception()
async def render_async(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
if not self.environment.is_async:
raise RuntimeError(
"The environment was not created with async mode enabled."
)
ctx = self.new_context(dict(*args, **kwargs))
try:
return self.environment_class.concat( # type: ignore
[n async for n in self.root_render_func(ctx)] # type: ignore
)
except Exception:
return self.environment.handle_exception()
NativeEnvironment.template_class = NativeTemplate

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"""The optimizer tries to constant fold expressions and modify the AST
in place so that it should be faster to evaluate.
Because the AST does not contain all the scoping information and the
compiler has to find that out, we cannot do all the optimizations we
want. For example, loop unrolling doesn't work because unrolled loops
would have a different scope. The solution would be a second syntax tree
that stored the scoping rules.
"""
import typing as t
from . import nodes
from .visitor import NodeTransformer
if t.TYPE_CHECKING:
from .environment import Environment
def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node:
"""The context hint can be used to perform an static optimization
based on the context given."""
optimizer = Optimizer(environment)
return t.cast(nodes.Node, optimizer.visit(node))
class Optimizer(NodeTransformer):
def __init__(self, environment: "t.Optional[Environment]") -> None:
self.environment = environment
def generic_visit(
self, node: nodes.Node, *args: t.Any, **kwargs: t.Any
) -> nodes.Node:
node = super().generic_visit(node, *args, **kwargs)
# Do constant folding. Some other nodes besides Expr have
# as_const, but folding them causes errors later on.
if isinstance(node, nodes.Expr):
try:
return nodes.Const.from_untrusted(
node.as_const(args[0] if args else None),
lineno=node.lineno,
environment=self.environment,
)
except nodes.Impossible:
pass
return node

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