53 lines
1.6 KiB
Text
53 lines
1.6 KiB
Text
/-
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Copyright (c) 2022 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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module
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prelude
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public import Lean.Data.AssocList
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public import Lean.HeadIndex
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public import Lean.Meta.Basic
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public section
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namespace Lean.Meta
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/--
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A mapping that identifies definitionally equal expressions.
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We implement it as a mapping from `HeadIndex` to `AssocList Expr α`.
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Remark: this map may be quite inefficient if there are many `HeadIndex` collisions.
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-/
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structure KExprMap (α : Type) where
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map : PHashMap HeadIndex (AssocList Expr α) := {}
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deriving Inhabited
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/-- Return `some v` if there is an entry `e ↦ v` in `m`. -/
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def KExprMap.find? (m : KExprMap α) (e : Expr) : MetaM (Option α) := do
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match m.map.find? e.toHeadIndex with
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| none => return none
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| some ps =>
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for ⟨e', a⟩ in ps do
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if (← isDefEq e e') then
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return some a
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return none
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private def updateList (ps : AssocList Expr α) (e : Expr) (v : α) : MetaM (AssocList Expr α) := do
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match ps with
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| AssocList.nil => return AssocList.cons e v ps
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| AssocList.cons e' v' ps =>
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if (← isDefEq e e') then
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return AssocList.cons e v ps
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else
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return AssocList.cons e' v' (← updateList ps e v)
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/-- Insert `e ↦ v` into `m` -/
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def KExprMap.insert (m : KExprMap α) (e : Expr) (v : α) : MetaM (KExprMap α) :=
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let k := e.toHeadIndex
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match m.map.find? k with
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| none => return { map := m.map.insert k (AssocList.cons e v AssocList.nil) }
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| some ps => return { map := m.map.insert k (← updateList ps e v) }
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end Lean.Meta
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