Class PreBuildVisitor

mypyc/irbuild/prebuildvisitor.py:54–305

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

class PreBuildVisitor(ExtendedTraverserVisitor):
    """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
    * Find module import groups

    The main IR build pass uses this information.
    """

    def __init__(
        self,
        errors: Errors,
        current_file: MypyFile,
        decorators_to_remove: dict[FuncDef, list[int]],
        types: dict[Expression, Type],
    ) -> 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

        # A mapping of import groups (a series of Import nodes with
        # nothing in between) where each group is keyed by its first
        # import node.
        self.module_import_groups: dict[Import, list[Import]] = {}