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