67a4ebbde6
Remark: the attribute actions used by the frontend are all in IO. These actions access attributes by name, and need access to the IO.ref that contains all registered attributes in the system.
47 lines
1.4 KiB
Text
47 lines
1.4 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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Author: Leonardo de Moura
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-/
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prelude
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import init.control.id
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universes u v w
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/- List-like type to avoid extra level of indirection -/
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inductive AssocList (α : Type u) (β : Type v)
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| nil {} : AssocList
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| cons (key : α) (value : β) (tail : AssocList) : AssocList
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namespace AssocList
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variables {α : Type u} {β : Type v} {δ : Type w} {m : Type w → Type w} [Monad m]
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@[specialize] def mfoldl (f : δ → α → β → m δ) : δ → AssocList α β → m δ
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| d nil := pure d
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| d (cons a b es) := do d ← f d a b, mfoldl d es
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@[inline] def foldl (f : δ → α → β → δ) (d : δ) (as : AssocList α β) : δ :=
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Id.run (mfoldl f d as)
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def find [HasBeq α] (a : α) : AssocList α β → Option β
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| nil := none
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| (cons k v es) := match k == a with
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| true := some v
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| false := find es
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def contains [HasBeq α] (a : α) : AssocList α β → Bool
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| nil := false
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| (cons k v es) := k == a || contains es
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def replace [HasBeq α] (a : α) (b : β) : AssocList α β → AssocList α β
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| nil := nil
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| (cons k v es) := match k == a with
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| true := cons a b es
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| false := cons k v (replace es)
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def erase [HasBeq α] (a : α) : AssocList α β → AssocList α β
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| nil := nil
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| (cons k v es) := match k == a with
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| true := es
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| false := cons k v (erase es)
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end AssocList
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