40 lines
1.2 KiB
Text
40 lines
1.2 KiB
Text
/-
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Copyright (c) 2020 Microsoft Corporation. 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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import Lean.Expr
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namespace Lean
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namespace CollectFVars
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structure State :=
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(visitedExpr : ExprSet := {})
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(fvarSet : NameSet := {})
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instance State.inhabited : Inhabited State := ⟨{}⟩
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abbrev Visitor := State → State
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@[inline] def visit (f : Expr → Visitor) (e : Expr) : Visitor :=
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fun s =>
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if !e.hasFVar || s.visitedExpr.contains e then s
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else f e { s with visitedExpr := s.visitedExpr.insert e }
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partial def main : Expr → Visitor
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| Expr.proj _ _ e _ => visit main e
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| Expr.forallE _ d b _ => visit main b ∘ visit main d
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| Expr.lam _ d b _ => visit main b ∘ visit main d
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| Expr.letE _ t v b _ => visit main b ∘ visit main v ∘ visit main t
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| Expr.app f a _ => visit main a ∘ visit main f
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| Expr.mdata _ b _ => visit main b
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| Expr.fvar fvarId _ => fun s => { s with fvarSet := s.fvarSet.insert fvarId }
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| _ => id
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end CollectFVars
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def collectFVars (s : CollectFVars.State) (e : Expr) : CollectFVars.State :=
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CollectFVars.main e s
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end Lean
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