From 097645aa9859f2c3847cf90d6e52e6f70eee4800 Mon Sep 17 00:00:00 2001
From: Robbert Krebbers <mail@robbertkrebbers.nl>
Date: Fri, 2 May 2014 22:36:50 +0200
Subject: [PATCH] Add finite map with integer keys Z.

---
 theories/zmap.v | 96 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 theories/zmap.v

diff --git a/theories/zmap.v b/theories/zmap.v
new file mode 100644
index 00000000..7c75dea7
--- /dev/null
+++ b/theories/zmap.v
@@ -0,0 +1,96 @@
+(* Copyright (c) 2012-2013, Robbert Krebbers. *)
+(* This file is distributed under the terms of the BSD license. *)
+(** This files extends the implementation of finite over [positive] to finite
+maps whose keys range over Coq's data type of binary naturals [Z]. *)
+Require Import pmap mapset.
+Require Export prelude fin_maps.
+Local Open Scope Z_scope.
+
+Record Zmap A :=
+  ZMap { Zmap_0 : option A; Zmap_pos : Pmap A; Zmap_neg : Pmap A }.
+Arguments Zmap_0 {_} _.
+Arguments Zmap_pos {_} _.
+Arguments Zmap_neg {_} _.
+Arguments ZMap {_} _ _ _.
+
+Instance Zmap_eq_dec `{∀ x y : A, Decision (x = y)} (t1 t2 : Zmap A) :
+  Decision (t1 = t2).
+Proof.
+ refine
+  match t1, t2 with
+  | ZMap x t1 t1', ZMap y t2 t2' =>
+     cast_if_and3 (decide (x = y)) (decide (t1 = t2)) (decide (t1' = t2'))
+  end; abstract congruence.
+Defined.
+Instance Zempty {A} : Empty (Zmap A) := ZMap None ∅ ∅.
+Instance Zlookup {A} : Lookup Z A (Zmap A) := λ i t,
+  match i with
+  | Z0 => Zmap_0 t | Zpos p => Zmap_pos t !! p | Zneg p => Zmap_neg t !! p
+  end.
+Instance Zpartial_alter {A} : PartialAlter Z A (Zmap A) := λ f i t,
+  match i, t with
+  | Z0, ZMap o t t' => ZMap (f o) t t'
+  | Zpos p, ZMap o t t' => ZMap o (partial_alter f p t) t'
+  | Zneg p, ZMap o t t' => ZMap o t (partial_alter f p t')
+  end.
+Instance Zto_list {A} : FinMapToList Z A (Zmap A) := λ t,
+  match t with
+  | ZMap o t t' => default [] o (λ x, [(0,x)]) ++
+     (prod_map Zpos id <$> map_to_list t) ++
+     (prod_map Zneg id <$> map_to_list t')
+  end.
+Instance Zomap: OMap Zmap := λ A B f t,
+  match t with ZMap o t t' => ZMap (o ≫= f) (omap f t) (omap f t') end.
+Instance Zmerge: Merge Zmap := λ A B C f t1 t2,
+  match t1, t2 with
+  | ZMap o1 t1 t1', ZMap o2 t2 t2' => ZMap (f o1 o2) (merge f t1 t2) (merge f t1' t2')
+  end.
+Instance Nfmap: FMap Zmap := λ A B f t,
+  match t with ZMap o t t' => ZMap (f <$> o) (f <$> t) (f <$> t') end.
+
+Instance: FinMap Z Zmap.
+Proof.
+  split.
+  * intros ? [??] [??] H. f_equal.
+    + apply (H 0).
+    + apply map_eq. intros i. apply (H (Zpos i)).
+    + apply map_eq. intros i. apply (H (Zneg i)).
+  * by intros ? [].
+  * intros ? f [] [|?|?]; simpl; [done| |]; apply lookup_partial_alter.
+  * intros ? f [] [|?|?] [|?|?]; simpl; intuition congruence ||
+      intros; apply lookup_partial_alter_ne; congruence.
+  * intros ??? [??] []; simpl; [done| |]; apply lookup_fmap.
+  * intros ? [o t t']; unfold map_to_list; simpl.
+    assert (NoDup ((prod_map Z.pos id <$> map_to_list t) ++
+      prod_map Z.neg id <$> map_to_list t')).
+    { apply NoDup_app; split_ands.
+      - apply (fmap_nodup _). apply map_to_list_nodup.
+      - intro. rewrite !elem_of_list_fmap. naive_solver.
+      - apply (fmap_nodup _). apply map_to_list_nodup. }
+    destruct o; simpl; auto. constructor; auto.
+    rewrite elem_of_app, !elem_of_list_fmap. naive_solver.
+  * intros ? t i x. unfold map_to_list. split.
+    + destruct t as [[y|] t t']; simpl.
+      - rewrite elem_of_cons, elem_of_app, !elem_of_list_fmap.
+        intros [?|[[[??][??]]|[[??][??]]]]; simplify_equality; simpl; [done| |];
+          by apply elem_of_map_to_list.
+      - rewrite elem_of_app, !elem_of_list_fmap. intros [[[??][??]]|[[??][??]]];
+          simplify_equality'; by apply elem_of_map_to_list.
+    + destruct t as [[y|] t t']; simpl.
+      - rewrite elem_of_cons, elem_of_app, !elem_of_list_fmap.
+        destruct i as [|i|i]; simpl; [intuition congruence| |].
+        { right; left. exists (i, x). by rewrite elem_of_map_to_list. }
+        right; right. exists (i, x). by rewrite elem_of_map_to_list.
+      - rewrite elem_of_app, !elem_of_list_fmap.
+        destruct i as [|i|i]; simpl; [done| |].
+        { left; exists (i, x). by rewrite elem_of_map_to_list. }
+        right; exists (i, x). by rewrite elem_of_map_to_list.
+  * intros ?? f [??] [|?|?]; simpl; [done| |]; apply (lookup_omap f).
+  * intros ??? f ? [??] [??] [|?|?]; simpl; [done| |]; apply (lookup_merge f).
+Qed.
+
+(** * Finite sets *)
+(** We construct sets of [Z]s satisfying extensional equality. *)
+Notation Zset := (mapset Zmap).
+Instance Zmap_dom {A} : Dom (Zmap A) Zset := mapset_dom.
+Instance: FinMapDom Z Zmap Zset := mapset_dom_spec.
-- 
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