From fe3110b85e512a1e21152247b46c336b57330d22 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Legat?= <benoit.legat@gmail.com>
Date: Fri, 16 May 2025 11:17:02 +0200
Subject: [PATCH 1/2] Implement mutable addition

---
 Project.toml               |  2 ++
 src/SymbolicUtils.jl       |  2 ++
 src/mutable_arithmetics.jl | 16 ++++++++++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 src/mutable_arithmetics.jl

diff --git a/Project.toml b/Project.toml
index 87ad76cf..afb8eeef 100644
--- a/Project.toml
+++ b/Project.toml
@@ -17,6 +17,7 @@ ExproniconLite = "55351af7-c7e9-48d6-89ff-24e801d99491"
 LabelledArrays = "2ee39098-c373-598a-b85f-a56591580800"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MultivariatePolynomials = "102ac46a-7ee4-5c85-9060-abc95bfdeaa3"
+MutableArithmetics = "d8a4904e-b15c-11e9-3269-09a3773c0cb0"
 NaNMath = "77ba4419-2d1f-58cd-9bb1-8ffee604a2e3"
 Setfield = "efcf1570-3423-57d1-acb7-fd33fddbac46"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
@@ -50,6 +51,7 @@ DynamicPolynomials = "0.5, 0.6"
 ExproniconLite = "0.10.14"
 LabelledArrays = "1.5"
 MultivariatePolynomials = "0.5"
+MutableArithmetics = "1.6.4"
 NaNMath = "0.3, 1.1.2"
 OhMyThreads = "0.7"
 ReverseDiff = "1"
diff --git a/src/SymbolicUtils.jl b/src/SymbolicUtils.jl
index 3c930f66..b55adfcb 100644
--- a/src/SymbolicUtils.jl
+++ b/src/SymbolicUtils.jl
@@ -82,5 +82,7 @@ include("code.jl")
 # Adjoints
 include("adjoints.jl")
 
+# Mutable Arithmetics
+include("mutable_arithmetics.jl")
 
 end # module
diff --git a/src/mutable_arithmetics.jl b/src/mutable_arithmetics.jl
new file mode 100644
index 00000000..1ac58e8d
--- /dev/null
+++ b/src/mutable_arithmetics.jl
@@ -0,0 +1,16 @@
+import MutableArithmetics as MA
+
+function MA.operate!!(::typeof(+), a::BasicSymbolic, b::BasicSymbolic)
+    if SymbolicUtils.isadd(a)
+        if SymbolicUtils.isadd(b)
+            for (k, v) in b.dict
+                a.dict[k] = MA.add!!(get(a.dict, k, 0), v)
+            end
+        else
+            a.dict[b] = MA.add!!(get(a.dict, b, 0), 1)
+        end
+        return a
+    else
+        return a + b
+    end
+end

From f6cfdc9de0f9333215cea8eeb5bda038a9fc6457 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Legat?= <benoit.legat@gmail.com>
Date: Fri, 16 May 2025 11:30:37 +0200
Subject: [PATCH 2/2] Add tests

---
 test/mutable_arithmetics.jl | 17 +++++++++++++++++
 test/runtests.jl            |  1 +
 2 files changed, 18 insertions(+)
 create mode 100644 test/mutable_arithmetics.jl

diff --git a/test/mutable_arithmetics.jl b/test/mutable_arithmetics.jl
new file mode 100644
index 00000000..b73a5b59
--- /dev/null
+++ b/test/mutable_arithmetics.jl
@@ -0,0 +1,17 @@
+using Test
+using MutableArithmetics
+using SymbolicUtils
+
+@syms x::Real y::Real
+v = repeat([x, y], 10)
+s = sum(v, init = 0)
+@test s.dict[x] == 10
+@test s.dict[y] == 10
+@test isequal(s, 10x + 10y) # ????
+
+a = x + y
+b = 2x + y
+c = add!!(a, b)
+@test c.dict[x] == 3
+@test c.dict[y] == 2
+@test isequal(c, 3x + 2y)
diff --git a/test/runtests.jl b/test/runtests.jl
index 0d58ad20..884ca893 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -18,5 +18,6 @@ using Pkg, Test, SafeTestsets
         @safetestset "Adjoints" begin include("adjoints.jl") end
         @safetestset "Hash Consing" begin include("hash_consing.jl") end
         @safetestset "Cache macro" begin include("cache_macro.jl") end
+        @safetestset "Cache macro" begin include("mutable_arithmetics.jl") end
     end
 end