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