From 4122f3fbcbb68af0d513cca429b9131816da036f Mon Sep 17 00:00:00 2001
From: Alexander McCord <alex@mccord.dev>
Date: Tue, 28 May 2024 08:31:25 -0700
Subject: [PATCH] Implement a basic version of Analysis. Will expand it later.

---
 EqSat/include/Luau/EGraph.h        | 21 +++++++++++++++++----
 tests/EqSat.propositional.test.cpp | 18 ++++++++++++++----
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/EqSat/include/Luau/EGraph.h b/EqSat/include/Luau/EGraph.h
index 6edcc6a7..903a0110 100644
--- a/EqSat/include/Luau/EGraph.h
+++ b/EqSat/include/Luau/EGraph.h
@@ -13,6 +13,20 @@
 namespace Luau::EqSat
 {
 
+template<typename L, typename N>
+class EGraph;
+
+template<typename L, typename N>
+struct Analysis final
+{
+    N analysis;
+
+    typename N::Data make(const EGraph<L, N>& egraph, const L& enode) const
+    {
+        return analysis.make(egraph, enode);
+    }
+};
+
 /// Each e-class is a set of e-nodes representing equivalent terms from a given language,
 /// and an e-node is a function symbol paired with a list of children e-classes.
 template<typename L, typename D>
@@ -28,6 +42,8 @@ struct EClass final
 template<typename L, typename N>
 class EGraph final
 {
+    Analysis<L, N> analysis;
+
     /// A union-find data structure 𝑈 stores an equivalence relation over e-class ids.
     UnionFind unionfind;
 
@@ -55,16 +71,13 @@ private:
         classes.insert_or_assign(id, EClass<L, typename N::Data>{
             id,
             {enode},
-            {}, // TODO: analysis make
+            analysis.make(*this, enode),
             {},
         });
         return id;
     }
 
 public:
-    // TODO: static_assert L <: Language
-    // TODO: static_assert N <: Analysis<L>
-
     Id find(Id id) const
     {
         return unionfind.find(id);
diff --git a/tests/EqSat.propositional.test.cpp b/tests/EqSat.propositional.test.cpp
index 940918a2..4988822a 100644
--- a/tests/EqSat.propositional.test.cpp
+++ b/tests/EqSat.propositional.test.cpp
@@ -26,12 +26,22 @@ using namespace Luau;
 
 using PropositionalLogic = EqSat::Language<Var, Bool, Not, And, Or, Implies>;
 
+using EGraph = EqSat::EGraph<PropositionalLogic, struct ConstantFold>;
+
 struct ConstantFold
 {
     using Data = std::optional<bool>;
-};
 
-using EGraph = EqSat::EGraph<PropositionalLogic, ConstantFold>;
+    Data make(const EGraph& egraph, const PropositionalLogic& enode) const
+    {
+        if (enode.get<Var>())
+            return std::nullopt;
+        else if (auto b = enode.get<Bool>())
+            return b->value;
+
+        return std::nullopt;
+    }
+};
 
 TEST_SUITE_BEGIN("EqSatPropositionalLogic");
 
@@ -54,8 +64,8 @@ TEST_CASE("egraph_data")
     EqSat::Id id1 = egraph.add(Bool{true});
     EqSat::Id id2 = egraph.add(Bool{false});
 
-    CHECK(egraph[id1].data == std::nullopt); // TODO: true
-    CHECK(egraph[id2].data == std::nullopt); // TODO: false
+    CHECK(egraph[id1].data == true);
+    CHECK(egraph[id2].data == false);
 }
 
 TEST_SUITE_END();