169 lines
6.9 KiB
Python
169 lines
6.9 KiB
Python
from mypyc.errors import Errors
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from typing import Dict, List, Set
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from mypy.nodes import (
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Decorator, Expression, FuncDef, FuncItem, LambdaExpr, NameExpr, SymbolNode, Var, MemberExpr,
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MypyFile
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)
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from mypy.traverser import TraverserVisitor
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class PreBuildVisitor(TraverserVisitor):
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"""Mypy file AST visitor run before building the IR.
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This collects various things, including:
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* Determine relationships between nested functions and functions that
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contain nested functions
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* Find non-local variables (free variables)
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* Find property setters
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* Find decorators of functions
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The main IR build pass uses this information.
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"""
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def __init__(
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self,
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errors: Errors,
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current_file: MypyFile,
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decorators_to_remove: Dict[FuncDef, List[int]],
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) -> None:
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super().__init__()
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# Dict from a function to symbols defined directly in the
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# function that are used as non-local (free) variables within a
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# nested function.
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self.free_variables: Dict[FuncItem, Set[SymbolNode]] = {}
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# Intermediate data structure used to find the function where
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# a SymbolNode is declared. Initially this may point to a
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# function nested inside the function with the declaration,
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# but we'll eventually update this to refer to the function
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# with the declaration.
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self.symbols_to_funcs: Dict[SymbolNode, FuncItem] = {}
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# Stack representing current function nesting.
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self.funcs: List[FuncItem] = []
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# All property setters encountered so far.
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self.prop_setters: Set[FuncDef] = set()
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# A map from any function that contains nested functions to
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# a set of all the functions that are nested within it.
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self.encapsulating_funcs: Dict[FuncItem, List[FuncItem]] = {}
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# Map nested function to its parent/encapsulating function.
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self.nested_funcs: Dict[FuncItem, FuncItem] = {}
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# Map function to its non-special decorators.
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self.funcs_to_decorators: Dict[FuncDef, List[Expression]] = {}
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# Map function to indices of decorators to remove
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self.decorators_to_remove: Dict[FuncDef, List[int]] = decorators_to_remove
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self.errors: Errors = errors
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self.current_file: MypyFile = current_file
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def visit_decorator(self, dec: Decorator) -> None:
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if dec.decorators:
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# Only add the function being decorated if there exist
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# (ordinary) decorators in the decorator list. Certain
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# decorators (such as @property, @abstractmethod) are
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# special cased and removed from this list by
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# mypy. Functions decorated only by special decorators
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# (and property setters) are not treated as decorated
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# functions by the IR builder.
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if isinstance(dec.decorators[0], MemberExpr) and dec.decorators[0].name == 'setter':
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# Property setters are not treated as decorated methods.
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self.prop_setters.add(dec.func)
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else:
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decorators_to_store = dec.decorators.copy()
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if dec.func in self.decorators_to_remove:
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to_remove = self.decorators_to_remove[dec.func]
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for i in reversed(to_remove):
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del decorators_to_store[i]
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# if all of the decorators are removed, we shouldn't treat this as a decorated
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# function because there aren't any decorators to apply
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if not decorators_to_store:
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return
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self.funcs_to_decorators[dec.func] = decorators_to_store
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super().visit_decorator(dec)
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def visit_func_def(self, fdef: FuncItem) -> None:
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# TODO: What about overloaded functions?
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self.visit_func(fdef)
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def visit_lambda_expr(self, expr: LambdaExpr) -> None:
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self.visit_func(expr)
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def visit_func(self, func: FuncItem) -> None:
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# If there were already functions or lambda expressions
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# defined in the function stack, then note the previous
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# FuncItem as containing a nested function and the current
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# FuncItem as being a nested function.
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if self.funcs:
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# Add the new func to the set of nested funcs within the
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# func at top of the func stack.
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self.encapsulating_funcs.setdefault(self.funcs[-1], []).append(func)
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# Add the func at top of the func stack as the parent of
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# new func.
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self.nested_funcs[func] = self.funcs[-1]
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self.funcs.append(func)
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super().visit_func(func)
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self.funcs.pop()
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def visit_name_expr(self, expr: NameExpr) -> None:
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if isinstance(expr.node, (Var, FuncDef)):
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self.visit_symbol_node(expr.node)
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def visit_var(self, var: Var) -> None:
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self.visit_symbol_node(var)
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def visit_symbol_node(self, symbol: SymbolNode) -> None:
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if not self.funcs:
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# We are not inside a function and hence do not need to do
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# anything regarding free variables.
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return
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if symbol in self.symbols_to_funcs:
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orig_func = self.symbols_to_funcs[symbol]
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if self.is_parent(self.funcs[-1], orig_func):
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# The function in which the symbol was previously seen is
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# nested within the function currently being visited. Thus
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# the current function is a better candidate to contain the
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# declaration.
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self.symbols_to_funcs[symbol] = self.funcs[-1]
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# TODO: Remove from the orig_func free_variables set?
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self.free_variables.setdefault(self.funcs[-1], set()).add(symbol)
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elif self.is_parent(orig_func, self.funcs[-1]):
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# The SymbolNode instance has already been visited
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# before in a parent function, thus it's a non-local
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# symbol.
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self.add_free_variable(symbol)
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else:
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# This is the first time the SymbolNode is being
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# visited. We map the SymbolNode to the current FuncDef
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# being visited to note where it was first visited.
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self.symbols_to_funcs[symbol] = self.funcs[-1]
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def is_parent(self, fitem: FuncItem, child: FuncItem) -> bool:
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# Check if child is nested within fdef (possibly indirectly
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# within multiple nested functions).
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if child in self.nested_funcs:
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parent = self.nested_funcs[child]
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if parent == fitem:
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return True
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return self.is_parent(fitem, parent)
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return False
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def add_free_variable(self, symbol: SymbolNode) -> None:
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# Find the function where the symbol was (likely) first declared,
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# and mark is as a non-local symbol within that function.
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func = self.symbols_to_funcs[symbol]
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self.free_variables.setdefault(func, set()).add(symbol)
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