| """The optimizer tries to constant fold expressions and modify the AST |
| in place so that it should be faster to evaluate. |
| |
| Because the AST does not contain all the scoping information and the |
| compiler has to find that out, we cannot do all the optimizations we |
| want. For example, loop unrolling doesn't work because unrolled loops |
| would have a different scope. The solution would be a second syntax tree |
| that stored the scoping rules. |
| """ |
|
|
| import typing as t |
|
|
| from . import nodes |
| from .visitor import NodeTransformer |
|
|
| if t.TYPE_CHECKING: |
| from .environment import Environment |
|
|
|
|
| def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node: |
| """The context hint can be used to perform an static optimization |
| based on the context given.""" |
| optimizer = Optimizer(environment) |
| return t.cast(nodes.Node, optimizer.visit(node)) |
|
|
|
|
| class Optimizer(NodeTransformer): |
| def __init__(self, environment: "t.Optional[Environment]") -> None: |
| self.environment = environment |
|
|
| def generic_visit( |
| self, node: nodes.Node, *args: t.Any, **kwargs: t.Any |
| ) -> nodes.Node: |
| node = super().generic_visit(node, *args, **kwargs) |
|
|
| |
| |
| if isinstance(node, nodes.Expr): |
| try: |
| return nodes.Const.from_untrusted( |
| node.as_const(args[0] if args else None), |
| lineno=node.lineno, |
| environment=self.environment, |
| ) |
| except nodes.Impossible: |
| pass |
|
|
| return node |
|
|
