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