init

.venv/lib/python3.8/site-packages/mypyc/irbuild/prebuildvisitor.py

@@ -0,0 +1,168 @@
+from mypyc.errors import Errors
+from typing import Dict, List, Set
+
+from mypy.nodes import (
+    Decorator, Expression, FuncDef, FuncItem, LambdaExpr, NameExpr, SymbolNode, Var, MemberExpr,
+    MypyFile
+)
+from mypy.traverser import TraverserVisitor
+
+
+class PreBuildVisitor(TraverserVisitor):
+    """Mypy file AST visitor run before building the IR.
+
+    This collects various things, including:
+
+    * Determine relationships between nested functions and functions that
+      contain nested functions
+    * Find non-local variables (free variables)
+    * Find property setters
+    * Find decorators of functions
+
+    The main IR build pass uses this information.
+    """
+
+    def __init__(
+        self,
+        errors: Errors,
+        current_file: MypyFile,
+        decorators_to_remove: Dict[FuncDef, List[int]],
+    ) -> None:
+        super().__init__()
+        # Dict from a function to symbols defined directly in the
+        # function that are used as non-local (free) variables within a
+        # nested function.
+        self.free_variables: Dict[FuncItem, Set[SymbolNode]] = {}
+
+        # Intermediate data structure used to find the function where
+        # a SymbolNode is declared. Initially this may point to a
+        # function nested inside the function with the declaration,
+        # but we'll eventually update this to refer to the function
+        # with the declaration.
+        self.symbols_to_funcs: Dict[SymbolNode, FuncItem] = {}
+
+        # Stack representing current function nesting.
+        self.funcs: List[FuncItem] = []
+
+        # All property setters encountered so far.
+        self.prop_setters: Set[FuncDef] = set()
+
+        # A map from any function that contains nested functions to
+        # a set of all the functions that are nested within it.
+        self.encapsulating_funcs: Dict[FuncItem, List[FuncItem]] = {}
+
+        # Map nested function to its parent/encapsulating function.
+        self.nested_funcs: Dict[FuncItem, FuncItem] = {}
+
+        # Map function to its non-special decorators.
+        self.funcs_to_decorators: Dict[FuncDef, List[Expression]] = {}
+
+        # Map function to indices of decorators to remove
+        self.decorators_to_remove: Dict[FuncDef, List[int]] = decorators_to_remove
+
+        self.errors: Errors = errors
+
+        self.current_file: MypyFile = current_file
+
+    def visit_decorator(self, dec: Decorator) -> None:
+        if dec.decorators:
+            # Only add the function being decorated if there exist
+            # (ordinary) decorators in the decorator list. Certain
+            # decorators (such as @property, @abstractmethod) are
+            # special cased and removed from this list by
+            # mypy. Functions decorated only by special decorators
+            # (and property setters) are not treated as decorated
+            # functions by the IR builder.
+            if isinstance(dec.decorators[0], MemberExpr) and dec.decorators[0].name == 'setter':
+                # Property setters are not treated as decorated methods.
+                self.prop_setters.add(dec.func)
+            else:
+                decorators_to_store = dec.decorators.copy()
+                if dec.func in self.decorators_to_remove:
+                    to_remove = self.decorators_to_remove[dec.func]
+
+                    for i in reversed(to_remove):
+                        del decorators_to_store[i]
+                    # if all of the decorators are removed, we shouldn't treat this as a decorated
+                    # function because there aren't any decorators to apply
+                    if not decorators_to_store:
+                        return
+
+                self.funcs_to_decorators[dec.func] = decorators_to_store
+        super().visit_decorator(dec)
+
+    def visit_func_def(self, fdef: FuncItem) -> None:
+        # TODO: What about overloaded functions?
+        self.visit_func(fdef)
+
+    def visit_lambda_expr(self, expr: LambdaExpr) -> None:
+        self.visit_func(expr)
+
+    def visit_func(self, func: FuncItem) -> None:
+        # If there were already functions or lambda expressions
+        # defined in the function stack, then note the previous
+        # FuncItem as containing a nested function and the current
+        # FuncItem as being a nested function.
+        if self.funcs:
+            # Add the new func to the set of nested funcs within the
+            # func at top of the func stack.
+            self.encapsulating_funcs.setdefault(self.funcs[-1], []).append(func)
+            # Add the func at top of the func stack as the parent of
+            # new func.
+            self.nested_funcs[func] = self.funcs[-1]
+
+        self.funcs.append(func)
+        super().visit_func(func)
+        self.funcs.pop()
+
+    def visit_name_expr(self, expr: NameExpr) -> None:
+        if isinstance(expr.node, (Var, FuncDef)):
+            self.visit_symbol_node(expr.node)
+
+    def visit_var(self, var: Var) -> None:
+        self.visit_symbol_node(var)
+
+    def visit_symbol_node(self, symbol: SymbolNode) -> None:
+        if not self.funcs:
+            # We are not inside a function and hence do not need to do
+            # anything regarding free variables.
+            return
+
+        if symbol in self.symbols_to_funcs:
+            orig_func = self.symbols_to_funcs[symbol]
+            if self.is_parent(self.funcs[-1], orig_func):
+                # The function in which the symbol was previously seen is
+                # nested within the function currently being visited. Thus
+                # the current function is a better candidate to contain the
+                # declaration.
+                self.symbols_to_funcs[symbol] = self.funcs[-1]
+                # TODO: Remove from the orig_func free_variables set?
+                self.free_variables.setdefault(self.funcs[-1], set()).add(symbol)
+
+            elif self.is_parent(orig_func, self.funcs[-1]):
+                # The SymbolNode instance has already been visited
+                # before in a parent function, thus it's a non-local
+                # symbol.
+                self.add_free_variable(symbol)
+
+        else:
+            # This is the first time the SymbolNode is being
+            # visited. We map the SymbolNode to the current FuncDef
+            # being visited to note where it was first visited.
+            self.symbols_to_funcs[symbol] = self.funcs[-1]
+
+    def is_parent(self, fitem: FuncItem, child: FuncItem) -> bool:
+        # Check if child is nested within fdef (possibly indirectly
+        # within multiple nested functions).
+        if child in self.nested_funcs:
+            parent = self.nested_funcs[child]
+            if parent == fitem:
+                return True
+            return self.is_parent(fitem, parent)
+        return False
+
+    def add_free_variable(self, symbol: SymbolNode) -> None:
+        # Find the function where the symbol was (likely) first declared,
+        # and mark is as a non-local symbol within that function.
+        func = self.symbols_to_funcs[symbol]
+        self.free_variables.setdefault(func, set()).add(symbol)