106 lines
4.1 KiB
Agda
106 lines
4.1 KiB
Agda
module Analysis.Sign where
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open import Data.String using (String) renaming (_≟_ to _≟ˢ_)
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open import Data.Product using (proj₁)
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open import Data.List using (foldr)
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open import Relation.Binary.PropositionalEquality using (_≡_; refl; sym; trans)
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open import Relation.Nullary using (¬_; Dec; yes; no)
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open import Language
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open import Lattice
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open import Utils using (Pairwise)
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import Lattice.Bundles.FiniteValueMap
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private module FixedHeightFiniteMap = Lattice.Bundles.FiniteValueMap.FromFiniteHeightLattice
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data Sign : Set where
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+ : Sign
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- : Sign
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0ˢ : Sign
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-- g for siGn; s is used for strings and i is not very descriptive.
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_≟ᵍ_ : IsDecidable (_≡_ {_} {Sign})
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_≟ᵍ_ + + = yes refl
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_≟ᵍ_ + - = no (λ ())
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_≟ᵍ_ + 0ˢ = no (λ ())
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_≟ᵍ_ - + = no (λ ())
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_≟ᵍ_ - - = yes refl
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_≟ᵍ_ - 0ˢ = no (λ ())
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_≟ᵍ_ 0ˢ + = no (λ ())
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_≟ᵍ_ 0ˢ - = no (λ ())
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_≟ᵍ_ 0ˢ 0ˢ = yes refl
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module _ (prog : Program) where
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open Program prog
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-- embelish 'sign' with a top and bottom element.
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open import Lattice.AboveBelow Sign _≡_ (record { ≈-refl = refl; ≈-sym = sym; ≈-trans = trans }) _≟ᵍ_ as AB
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using ()
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renaming (AboveBelow to SignLattice; ≈-dec to ≈ᵍ-dec)
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-- 'sign' has no underlying lattice structure, so use the 'plain' above-below lattice.
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open AB.Plain using () renaming (finiteHeightLattice to finiteHeightLatticeᵍ-if-inhabited)
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finiteHeightLatticeᵍ = finiteHeightLatticeᵍ-if-inhabited 0ˢ
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-- The variable -> sign map is a finite value-map with keys strings. Use a bundle to avoid explicitly specifying operators.
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open FixedHeightFiniteMap String SignLattice _≟ˢ_ finiteHeightLatticeᵍ vars-Unique ≈ᵍ-dec
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using ()
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renaming
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( finiteHeightLattice to finiteHeightLatticeᵛ
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; FiniteMap to VariableSigns
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; _≈_ to _≈ᵛ_
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; _⊔_ to _⊔ᵛ_
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; ≈-dec to ≈ᵛ-dec
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)
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open FiniteHeightLattice finiteHeightLatticeᵛ
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using ()
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renaming
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( ⊔-Monotonicˡ to ⊔ᵛ-Monotonicˡ
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; ⊔-Monotonicʳ to ⊔ᵛ-Monotonicʳ
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; _≼_ to _≼ᵛ_
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; joinSemilattice to joinSemilatticeᵛ
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; ⊔-idemp to ⊔ᵛ-idemp
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)
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⊥ᵛ = proj₁ (proj₁ (proj₁ (FiniteHeightLattice.fixedHeight finiteHeightLatticeᵛ)))
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-- Finally, the map we care about is (state -> (variables -> sign)). Bring that in.
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module StateVariablesFiniteMap = FixedHeightFiniteMap State VariableSigns _≟_ finiteHeightLatticeᵛ states-Unique ≈ᵛ-dec
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open StateVariablesFiniteMap
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using (_[_]; m₁≼m₂⇒m₁[ks]≼m₂[ks])
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renaming
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( finiteHeightLattice to finiteHeightLatticeᵐ
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; FiniteMap to StateVariables
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; isLattice to isLatticeᵐ
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)
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open FiniteHeightLattice finiteHeightLatticeᵐ
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using ()
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renaming (_≼_ to _≼ᵐ_)
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-- build up the 'join' function, which follows from Exercise 4.26's
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--
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-- L₁ → (A → L₂)
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--
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-- Construction, with L₁ = (A → L₂), and f = id
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joinForKey : State → StateVariables → VariableSigns
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joinForKey k states = foldr _⊔ᵛ_ ⊥ᵛ (states [ incoming k ])
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-- The per-key join is made up of map key accesses (which are monotonic)
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-- and folds using the join operation (also monotonic)
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joinForKey-Mono : ∀ (k : State) → Monotonic _≼ᵐ_ _≼ᵛ_ (joinForKey k)
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joinForKey-Mono k {fm₁} {fm₂} fm₁≼fm₂ =
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foldr-Mono joinSemilatticeᵛ joinSemilatticeᵛ (fm₁ [ incoming k ]) (fm₂ [ incoming k ]) _⊔ᵛ_ ⊥ᵛ ⊥ᵛ
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(m₁≼m₂⇒m₁[ks]≼m₂[ks] fm₁ fm₂ (incoming k) fm₁≼fm₂)
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(⊔ᵛ-idemp ⊥ᵛ) ⊔ᵛ-Monotonicʳ ⊔ᵛ-Monotonicˡ
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-- The name f' comes from the formulation of Exercise 4.26.
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open StateVariablesFiniteMap.GeneralizedUpdate states isLatticeᵐ (λ x → x) (λ a₁≼a₂ → a₁≼a₂) joinForKey joinForKey-Mono states
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renaming
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( f' to joinAll
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; f'-Monotonic to joinAll-Mono
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)
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