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319 lines
10 KiB
319 lines
10 KiB
3 years ago
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import typing as t
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from . import nodes
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from .visitor import NodeVisitor
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VAR_LOAD_PARAMETER = "param"
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VAR_LOAD_RESOLVE = "resolve"
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VAR_LOAD_ALIAS = "alias"
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VAR_LOAD_UNDEFINED = "undefined"
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def find_symbols(
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nodes: t.Iterable[nodes.Node], parent_symbols: t.Optional["Symbols"] = None
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) -> "Symbols":
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sym = Symbols(parent=parent_symbols)
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visitor = FrameSymbolVisitor(sym)
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for node in nodes:
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visitor.visit(node)
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return sym
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def symbols_for_node(
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node: nodes.Node, parent_symbols: t.Optional["Symbols"] = None
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) -> "Symbols":
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sym = Symbols(parent=parent_symbols)
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sym.analyze_node(node)
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return sym
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class Symbols:
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def __init__(
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self, parent: t.Optional["Symbols"] = None, level: t.Optional[int] = None
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) -> None:
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if level is None:
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if parent is None:
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level = 0
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else:
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level = parent.level + 1
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self.level: int = level
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self.parent = parent
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self.refs: t.Dict[str, str] = {}
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self.loads: t.Dict[str, t.Any] = {}
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self.stores: t.Set[str] = set()
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def analyze_node(self, node: nodes.Node, **kwargs: t.Any) -> None:
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visitor = RootVisitor(self)
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visitor.visit(node, **kwargs)
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def _define_ref(
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self, name: str, load: t.Optional[t.Tuple[str, t.Optional[str]]] = None
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) -> str:
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ident = f"l_{self.level}_{name}"
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self.refs[name] = ident
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if load is not None:
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self.loads[ident] = load
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return ident
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def find_load(self, target: str) -> t.Optional[t.Any]:
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if target in self.loads:
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return self.loads[target]
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if self.parent is not None:
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return self.parent.find_load(target)
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return None
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def find_ref(self, name: str) -> t.Optional[str]:
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if name in self.refs:
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return self.refs[name]
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if self.parent is not None:
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return self.parent.find_ref(name)
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return None
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def ref(self, name: str) -> str:
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rv = self.find_ref(name)
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if rv is None:
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raise AssertionError(
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"Tried to resolve a name to a reference that was"
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f" unknown to the frame ({name!r})"
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)
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return rv
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def copy(self) -> "Symbols":
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rv = object.__new__(self.__class__)
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rv.__dict__.update(self.__dict__)
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rv.refs = self.refs.copy()
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rv.loads = self.loads.copy()
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rv.stores = self.stores.copy()
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return rv
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def store(self, name: str) -> None:
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self.stores.add(name)
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# If we have not see the name referenced yet, we need to figure
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# out what to set it to.
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if name not in self.refs:
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# If there is a parent scope we check if the name has a
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# reference there. If it does it means we might have to alias
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# to a variable there.
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if self.parent is not None:
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outer_ref = self.parent.find_ref(name)
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if outer_ref is not None:
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self._define_ref(name, load=(VAR_LOAD_ALIAS, outer_ref))
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return
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# Otherwise we can just set it to undefined.
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self._define_ref(name, load=(VAR_LOAD_UNDEFINED, None))
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def declare_parameter(self, name: str) -> str:
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self.stores.add(name)
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return self._define_ref(name, load=(VAR_LOAD_PARAMETER, None))
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def load(self, name: str) -> None:
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if self.find_ref(name) is None:
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self._define_ref(name, load=(VAR_LOAD_RESOLVE, name))
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def branch_update(self, branch_symbols: t.Sequence["Symbols"]) -> None:
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stores: t.Dict[str, int] = {}
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for branch in branch_symbols:
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for target in branch.stores:
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if target in self.stores:
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continue
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stores[target] = stores.get(target, 0) + 1
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for sym in branch_symbols:
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self.refs.update(sym.refs)
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self.loads.update(sym.loads)
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self.stores.update(sym.stores)
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for name, branch_count in stores.items():
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if branch_count == len(branch_symbols):
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continue
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target = self.find_ref(name) # type: ignore
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assert target is not None, "should not happen"
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if self.parent is not None:
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outer_target = self.parent.find_ref(name)
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if outer_target is not None:
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self.loads[target] = (VAR_LOAD_ALIAS, outer_target)
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continue
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self.loads[target] = (VAR_LOAD_RESOLVE, name)
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def dump_stores(self) -> t.Dict[str, str]:
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rv: t.Dict[str, str] = {}
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node: t.Optional["Symbols"] = self
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while node is not None:
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for name in sorted(node.stores):
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if name not in rv:
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rv[name] = self.find_ref(name) # type: ignore
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node = node.parent
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return rv
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def dump_param_targets(self) -> t.Set[str]:
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rv = set()
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node: t.Optional["Symbols"] = self
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while node is not None:
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for target, (instr, _) in self.loads.items():
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if instr == VAR_LOAD_PARAMETER:
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rv.add(target)
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node = node.parent
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return rv
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class RootVisitor(NodeVisitor):
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def __init__(self, symbols: "Symbols") -> None:
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self.sym_visitor = FrameSymbolVisitor(symbols)
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def _simple_visit(self, node: nodes.Node, **kwargs: t.Any) -> None:
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for child in node.iter_child_nodes():
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self.sym_visitor.visit(child)
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visit_Template = _simple_visit
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visit_Block = _simple_visit
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visit_Macro = _simple_visit
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visit_FilterBlock = _simple_visit
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visit_Scope = _simple_visit
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visit_If = _simple_visit
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visit_ScopedEvalContextModifier = _simple_visit
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def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
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for child in node.body:
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self.sym_visitor.visit(child)
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def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
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for child in node.iter_child_nodes(exclude=("call",)):
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self.sym_visitor.visit(child)
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def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
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for child in node.body:
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self.sym_visitor.visit(child)
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def visit_For(
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self, node: nodes.For, for_branch: str = "body", **kwargs: t.Any
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) -> None:
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if for_branch == "body":
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self.sym_visitor.visit(node.target, store_as_param=True)
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branch = node.body
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elif for_branch == "else":
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branch = node.else_
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elif for_branch == "test":
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self.sym_visitor.visit(node.target, store_as_param=True)
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if node.test is not None:
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self.sym_visitor.visit(node.test)
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return
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else:
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raise RuntimeError("Unknown for branch")
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if branch:
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for item in branch:
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self.sym_visitor.visit(item)
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def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
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for target in node.targets:
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self.sym_visitor.visit(target)
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for child in node.body:
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self.sym_visitor.visit(child)
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def generic_visit(self, node: nodes.Node, *args: t.Any, **kwargs: t.Any) -> None:
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raise NotImplementedError(f"Cannot find symbols for {type(node).__name__!r}")
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class FrameSymbolVisitor(NodeVisitor):
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"""A visitor for `Frame.inspect`."""
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def __init__(self, symbols: "Symbols") -> None:
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self.symbols = symbols
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def visit_Name(
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self, node: nodes.Name, store_as_param: bool = False, **kwargs: t.Any
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) -> None:
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"""All assignments to names go through this function."""
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if store_as_param or node.ctx == "param":
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self.symbols.declare_parameter(node.name)
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elif node.ctx == "store":
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self.symbols.store(node.name)
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elif node.ctx == "load":
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self.symbols.load(node.name)
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def visit_NSRef(self, node: nodes.NSRef, **kwargs: t.Any) -> None:
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self.symbols.load(node.name)
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def visit_If(self, node: nodes.If, **kwargs: t.Any) -> None:
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self.visit(node.test, **kwargs)
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original_symbols = self.symbols
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def inner_visit(nodes: t.Iterable[nodes.Node]) -> "Symbols":
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self.symbols = rv = original_symbols.copy()
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for subnode in nodes:
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self.visit(subnode, **kwargs)
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self.symbols = original_symbols
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return rv
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body_symbols = inner_visit(node.body)
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elif_symbols = inner_visit(node.elif_)
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else_symbols = inner_visit(node.else_ or ())
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self.symbols.branch_update([body_symbols, elif_symbols, else_symbols])
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def visit_Macro(self, node: nodes.Macro, **kwargs: t.Any) -> None:
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self.symbols.store(node.name)
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def visit_Import(self, node: nodes.Import, **kwargs: t.Any) -> None:
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self.generic_visit(node, **kwargs)
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self.symbols.store(node.target)
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def visit_FromImport(self, node: nodes.FromImport, **kwargs: t.Any) -> None:
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self.generic_visit(node, **kwargs)
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for name in node.names:
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if isinstance(name, tuple):
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self.symbols.store(name[1])
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else:
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self.symbols.store(name)
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def visit_Assign(self, node: nodes.Assign, **kwargs: t.Any) -> None:
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"""Visit assignments in the correct order."""
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self.visit(node.node, **kwargs)
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self.visit(node.target, **kwargs)
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def visit_For(self, node: nodes.For, **kwargs: t.Any) -> None:
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"""Visiting stops at for blocks. However the block sequence
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is visited as part of the outer scope.
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"""
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self.visit(node.iter, **kwargs)
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def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
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self.visit(node.call, **kwargs)
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def visit_FilterBlock(self, node: nodes.FilterBlock, **kwargs: t.Any) -> None:
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self.visit(node.filter, **kwargs)
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def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
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for target in node.values:
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self.visit(target)
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def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
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"""Stop visiting at block assigns."""
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self.visit(node.target, **kwargs)
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def visit_Scope(self, node: nodes.Scope, **kwargs: t.Any) -> None:
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"""Stop visiting at scopes."""
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def visit_Block(self, node: nodes.Block, **kwargs: t.Any) -> None:
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"""Stop visiting at blocks."""
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def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
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"""Do not visit into overlay scopes."""
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