9e30ac3265
This PR adds the predicate `Expr.fvarsSet a b`, which returns `true` if and only if the free variables in `a` are a subset of the free variables in `b`.
25 lines
754 B
Text
25 lines
754 B
Text
/-
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Copyright (c) 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura
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-/
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prelude
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import Lean.Util.CollectFVars
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import Lean.Util.FindExpr
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namespace Lean.Expr
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/-- Returns true if the free variables in `a` are subset of the free variables in `b`. -/
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def fvarsSubset (a b : Expr) : Bool :=
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if !a.hasFVar then
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true -- Empty set is subset of anything
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else if !b.hasFVar then
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false -- Empty set is not a superset of a nonempty set.
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else
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let s := collectFVars {} b
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Option.isNone <| a.findExt? fun e =>
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if !e.hasFVar then .done
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else if e.isFVar && !s.fvarSet.contains e.fvarId! then .found
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else .visit
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end Lean.Expr
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