codekingpro/portable-devtools

1"""The optimizer tries to constant fold expressions and modify the AST2in place so that it should be faster to evaluate.3 4Because the AST does not contain all the scoping information and the5compiler has to find that out, we cannot do all the optimizations we6want. For example, loop unrolling doesn't work because unrolled loops7would have a different scope. The solution would be a second syntax tree8that stored the scoping rules.9"""10 11import typing as t12 13from . import nodes14from .visitor import NodeTransformer15 16if t.TYPE_CHECKING:17    from .environment import Environment18 19 20def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node:21    """The context hint can be used to perform an static optimization22    based on the context given."""23    optimizer = Optimizer(environment)24    return t.cast(nodes.Node, optimizer.visit(node))25 26 27class Optimizer(NodeTransformer):28    def __init__(self, environment: "t.Optional[Environment]") -> None:29        self.environment = environment30 31    def generic_visit(32        self, node: nodes.Node, *args: t.Any, **kwargs: t.Any33    ) -> nodes.Node:34        node = super().generic_visit(node, *args, **kwargs)35 36        # Do constant folding. Some other nodes besides Expr have37        # as_const, but folding them causes errors later on.38        if isinstance(node, nodes.Expr):39            try:40                return nodes.Const.from_untrusted(41                    node.as_const(args[0] if args else None),42                    lineno=node.lineno,43                    environment=self.environment,44                )45            except nodes.Impossible:46                pass47 48        return node49