lean4-htt/src/Lean/Util/FindLevelMVar.lean
2024-02-18 14:55:17 -08:00

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/-
Copyright (c) 2021 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Daniel Selsam
-/
prelude
import Lean.Expr
namespace Lean
namespace FindLevelMVar
abbrev Visitor := Option LMVarId → Option LMVarId
mutual
partial def visit (p : LMVarId → Bool) (e : Expr) : Visitor := fun s =>
if s.isSome || !e.hasLevelMVar then s else main p e s
partial def main (p : LMVarId → Bool) : Expr → Visitor
| .sort l => visitLevel p l
| .const _ ls => ls.foldr (init := id) fun l acc => visitLevel p l ∘ acc
| .forallE _ d b _ => visit p b ∘ visit p d
| .lam _ d b _ => visit p b ∘ visit p d
| .letE _ t v b _ => visit p b ∘ visit p v ∘ visit p t
| .app f a => visit p a ∘ visit p f
| .mdata _ b => visit p b
| .proj _ _ e => visit p e
| _ => id
partial def visitLevel (p : LMVarId → Bool) (l : Level) : Visitor := fun s =>
if s.isSome || !l.hasMVar then s else mainLevel p l s
partial def mainLevel (p : LMVarId → Bool) : Level → Visitor
| .zero => id
| .succ l => visitLevel p l
| .max l₁ l₂ => visitLevel p l₁ ∘ visitLevel p l₂
| .imax l₁ l₂ => visitLevel p l₁ ∘ visitLevel p l₂
| .param _ => id
| .mvar mvarId => fun s => if p mvarId then some mvarId else s
end
end FindLevelMVar
@[inline] def Expr.findLevelMVar? (e : Expr) (p : LMVarId → Bool) : Option LMVarId :=
FindLevelMVar.main p e none
end Lean