From 91307509d368eaafc7194cadd214278cb4c9d83a Mon Sep 17 00:00:00 2001
From: OverHash <46231745+OverHash@users.noreply.github.com>
Date: Mon, 13 Jul 2020 23:12:14 +1200
Subject: [PATCH 1/5] Make didChange.lua

---
 src/didChange.lua      | 50 +++++++++++++++++++++
 src/didChange.spec.lua | 99 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 149 insertions(+)
 create mode 100644 src/didChange.lua
 create mode 100644 src/didChange.spec.lua

diff --git a/src/didChange.lua b/src/didChange.lua
new file mode 100644
index 0000000..0f6b5aa
--- /dev/null
+++ b/src/didChange.lua
@@ -0,0 +1,50 @@
+--[[
+	A function that can be used to determine if a new value is equal to the old
+	value, recursively
+]]
+
+local didChange
+
+didChange = function(original, new)
+	-- if both original and new aren't tables, compare
+	if not (type(original) == 'table' and type(new) == 'table') then
+		return original ~= new
+	end
+
+	print(new, type(new), original, type(original))
+
+	-- compare new to old
+	for key, value in pairs(new) do
+		-- check for changed keys
+		print(key, value, original[key], original[key] ~= value)
+		if not (type(original[key]) == 'table' and type(value) == 'table') then
+			if original[key] ~= value then
+				return true
+			end
+		end
+
+		-- repeat for children
+		if type(value) == 'table' then
+			return didChange(original[key], value)
+		end
+	end
+
+	-- compare old to new
+	for key, value in pairs(original) do
+		-- check for changed keys
+		if not (type(value) == 'table' and type(new[key]) == 'table') then
+			if value ~= new[key] then
+				return true
+			end
+		end
+
+		-- repeat for children
+		if type(value) == 'table' then
+			return didChange(value, new[key])
+		end
+	end
+
+	return false
+end
+
+return didChange
diff --git a/src/didChange.spec.lua b/src/didChange.spec.lua
new file mode 100644
index 0000000..a85563c
--- /dev/null
+++ b/src/didChange.spec.lua
@@ -0,0 +1,99 @@
+return function()
+	local didChange = require(script.Parent.didChange)
+
+	it("should return true for changed non-table to non-table values", function()
+		local original = "hello"
+		local new = "world"
+
+		local isDifferent = didChange(original, new)
+		expect(isDifferent).to.equal(true)
+	end)
+
+	it("should return false for not-changed non-table to non-table values", function()
+		local original = "hello world"
+		local new = "hello world"
+
+		local isDifferent = didChange(original, new)
+		expect(isDifferent).to.equal(false)
+	end)
+
+	it("should return true for changed table to table values", function()
+		-- check same key change
+		local original = {
+			key = "hello"
+		}
+		local new = {
+			key = "world"
+		}
+
+		local isDifferent = didChange(original, new)
+		print('isDiff?', isDifferent)
+		expect(isDifferent).to.equal(true)
+
+		-- check new key added
+		original = {
+			key = "hello"
+		}
+		new = {
+			key = "hello",
+			otherKey = "world"
+		}
+
+		isDifferent = didChange(original, new)
+		print('isDiff2?', isDifferent)
+		expect(isDifferent).to.equal(true)
+
+		-- check key removed
+		original = {
+			key = "hello"
+		}
+		new = {}
+
+		isDifferent = didChange(original, new)
+		print('isDiff3?', isDifferent)
+		expect(isDifferent).to.equal(true)
+
+		-- check recursive
+		original = {
+			data = {
+				key = "hello"
+			}
+		}
+		new = {
+			data = {
+				key = "world"
+			}
+		}
+
+		isDifferent = didChange(original, new)
+		print('isDiff4?', isDifferent)
+		expect(isDifferent).to.equal(true)
+	end)
+
+	it("should return false for not changed table to table values", function()
+		local original = {
+			key = "hello world"
+		}
+		local new = {
+			key = "hello world"
+		}
+
+		local isDifferent = didChange(original, new)
+		expect(isDifferent).to.equal(false)
+
+		-- check recursive
+		original = {
+			data = {
+				key = "hello world"
+			}
+		}
+		new = {
+			data = {
+				key = "hello world"
+			}
+		}
+
+		isDifferent = didChange(original, new)
+		expect(isDifferent).to.equal(false)
+	end)
+end

From bb57baf2e29733beb3e84de3e3ebf9d2c12b542f Mon Sep 17 00:00:00 2001
From: OverHash <46231745+OverHash@users.noreply.github.com>
Date: Mon, 13 Jul 2020 23:12:42 +1200
Subject: [PATCH 2/5] Create spec for not fire changed event on no change

---
 src/Store.spec.lua | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/Store.spec.lua b/src/Store.spec.lua
index 5e7a5fd..5e030fa 100644
--- a/src/Store.spec.lua
+++ b/src/Store.spec.lua
@@ -313,8 +313,13 @@ return function()
 
 	describe("flush", function()
 		it("should not fire a changed event if there were no dispatches", function()
-			local store = Store.new(function()
-			end)
+			local store = Store.new(function(state, action)
+				if action.type == 'increment' then
+					return state + 1
+				end
+
+				return state
+			end, 0)
 
 			local count = 0
 			store.changed:connect(function()
@@ -338,5 +343,31 @@ return function()
 
 			store:destruct()
 		end)
+
+		it("should not fire a changed event if the state did not change", function()
+			local store = Store.new(function(state, action)
+				return {
+					state = "non-changed state"
+				}
+			end, {
+				state = "non-changed state"
+			})
+
+			local count = 0
+			store.changed:connect(function()
+				print("store changed")
+				count = count + 1
+			end)
+
+			store:dispatch({
+				type = ""
+			})
+
+			store:flush()
+
+			expect(count).to.equal(0)
+
+			store:destruct()
+		end)
 	end)
 end

From d4010a91a77c9f5d279fea6a3a36701953c3eeb3 Mon Sep 17 00:00:00 2001
From: OverHash <46231745+OverHash@users.noreply.github.com>
Date: Mon, 13 Jul 2020 23:12:56 +1200
Subject: [PATCH 3/5] Check for store changes before running .changed

---
 src/Store.lua | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/Store.lua b/src/Store.lua
index 90aa02f..548851e 100644
--- a/src/Store.lua
+++ b/src/Store.lua
@@ -1,5 +1,6 @@
 local RunService = game:GetService("RunService")
 
+local didChange = require(script.Parent.didChange)
 local Signal = require(script.Parent.Signal)
 local NoYield = require(script.Parent.NoYield)
 
@@ -86,8 +87,11 @@ function Store:dispatch(action)
 			error("action does not have a type field", 2)
 		end
 
-		self._state = self._reducer(self._state, action)
-		self._mutatedSinceFlush = true
+		local newState = self._reducer(self._state, action)
+		if didChange(self._state, newState) then
+			self._mutatedSinceFlush = true
+		end
+		self._state = newState
 	else
 		error(("actions of type %q are not permitted"):format(typeof(action)), 2)
 	end

From bb0b23b264fd496a0bdd90fcb155df249bc11a0b Mon Sep 17 00:00:00 2001
From: OverHash <46231745+OverHash@users.noreply.github.com>
Date: Tue, 14 Jul 2020 09:36:56 +1200
Subject: [PATCH 4/5] remove print statements

---
 src/didChange.lua      | 3 ---
 src/didChange.spec.lua | 4 ----
 2 files changed, 7 deletions(-)

diff --git a/src/didChange.lua b/src/didChange.lua
index 0f6b5aa..b8cabc6 100644
--- a/src/didChange.lua
+++ b/src/didChange.lua
@@ -11,12 +11,9 @@ didChange = function(original, new)
 		return original ~= new
 	end
 
-	print(new, type(new), original, type(original))
-
 	-- compare new to old
 	for key, value in pairs(new) do
 		-- check for changed keys
-		print(key, value, original[key], original[key] ~= value)
 		if not (type(original[key]) == 'table' and type(value) == 'table') then
 			if original[key] ~= value then
 				return true
diff --git a/src/didChange.spec.lua b/src/didChange.spec.lua
index a85563c..46bf9ab 100644
--- a/src/didChange.spec.lua
+++ b/src/didChange.spec.lua
@@ -27,7 +27,6 @@ return function()
 		}
 
 		local isDifferent = didChange(original, new)
-		print('isDiff?', isDifferent)
 		expect(isDifferent).to.equal(true)
 
 		-- check new key added
@@ -40,7 +39,6 @@ return function()
 		}
 
 		isDifferent = didChange(original, new)
-		print('isDiff2?', isDifferent)
 		expect(isDifferent).to.equal(true)
 
 		-- check key removed
@@ -50,7 +48,6 @@ return function()
 		new = {}
 
 		isDifferent = didChange(original, new)
-		print('isDiff3?', isDifferent)
 		expect(isDifferent).to.equal(true)
 
 		-- check recursive
@@ -66,7 +63,6 @@ return function()
 		}
 
 		isDifferent = didChange(original, new)
-		print('isDiff4?', isDifferent)
 		expect(isDifferent).to.equal(true)
 	end)
 

From 1ed7417f06b0eb79f3e7643304a4d83298889e0f Mon Sep 17 00:00:00 2001
From: OverHash <46231745+OverHash@users.noreply.github.com>
Date: Tue, 14 Jul 2020 10:24:03 +1200
Subject: [PATCH 5/5] Fix didChange to check children of original

---
 src/didChange.lua | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/didChange.lua b/src/didChange.lua
index b8cabc6..e605b98 100644
--- a/src/didChange.lua
+++ b/src/didChange.lua
@@ -22,7 +22,9 @@ didChange = function(original, new)
 
 		-- repeat for children
 		if type(value) == 'table' then
-			return didChange(original[key], value)
+			if didChange(original[key], value) then
+				return true
+			end
 		end
 	end
 
@@ -37,7 +39,9 @@ didChange = function(original, new)
 
 		-- repeat for children
 		if type(value) == 'table' then
-			return didChange(value, new[key])
+			if didChange(value, new[key]) then
+				return true
+			end
 		end
 	end