59 lines
1.7 KiB
Text
59 lines
1.7 KiB
Text
/-
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Copyright (c) 2019 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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prelude
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import init.lean.expr
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namespace Lean
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namespace Compiler
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def neutralExpr : Expr := Expr.const `_neutral []
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def unreachableExpr : Expr := Expr.const `_unreachable []
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def objectType : Expr := Expr.const `_obj []
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def voidType : Expr := Expr.const `_void []
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def mkLcProof (pred : Expr) := Expr.app (Expr.const `lcProof []) pred
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namespace atMostOnce
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structure AtMostOnceData :=
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(found result : Bool)
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def Visitor := AtMostOnceData → AtMostOnceData
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@[inline] def seq (f g : Visitor) : Visitor :=
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λ d, match f d with
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| ⟨found, false⟩ := ⟨found, false⟩
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| other := g other
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instance : HasAndthen Visitor :=
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⟨seq⟩
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@[inline] def skip : Visitor := id
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@[inline] def visitFVar (x y : Name) : Visitor
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| d@{result := false, ..} := d
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| {found := false, result := true} := {found := x == y, result := true}
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| {found := true, result := true} := {found := true, result := x != y}
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def visit (x : Name) : Expr → Visitor
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| (Expr.fvar y) := visitFVar y x
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| (Expr.app f a) := visit a; visit f
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| (Expr.lam _ _ d b) := visit d; visit b
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| (Expr.pi _ _ d b) := visit d; visit b
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| (Expr.elet _ t v b) := visit t; visit v; visit b
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| (Expr.mdata _ e) := visit e
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| (Expr.proj _ _ e) := visit e
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| _ := skip
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end atMostOnce
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/-- Return true iff the free variable with id `x` occurs at most once in `e` -/
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@[export lean.at_most_once_core]
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def atMostOnce (e : Expr) (x : Name) : Bool :=
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let {result := result, ..} := atMostOnce.visit x e {found := false, result := true} in
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result
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end Compiler
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end Lean
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