From a30bb945d262e18e634cd17d486508911b297ac5 Mon Sep 17 00:00:00 2001
From: Kyle Corry <kylecorry31@gmail.com>
Date: Thu, 28 Mar 2024 19:05:09 -0400
Subject: [PATCH] Add equality change detector

---
 .../kylecorry/luna/equality/ChangeDetector.kt |  6 +++
 .../luna/equality/EqualityChangeDetector.kt   | 44 +++++++++++++++++++
 .../{hash => equality}/HashChangeDetector.kt  |  8 ++--
 .../luna/{hash => equality}/HashUtils.kt      |  2 +-
 .../kotlin/com/kylecorry/luna/hooks/Effect.kt |  4 +-
 .../com/kylecorry/luna/hooks/MemoizedValue.kt |  4 +-
 6 files changed, 59 insertions(+), 9 deletions(-)
 create mode 100644 src/main/kotlin/com/kylecorry/luna/equality/ChangeDetector.kt
 create mode 100644 src/main/kotlin/com/kylecorry/luna/equality/EqualityChangeDetector.kt
 rename src/main/kotlin/com/kylecorry/luna/{hash => equality}/HashChangeDetector.kt (82%)
 rename src/main/kotlin/com/kylecorry/luna/{hash => equality}/HashUtils.kt (85%)

diff --git a/src/main/kotlin/com/kylecorry/luna/equality/ChangeDetector.kt b/src/main/kotlin/com/kylecorry/luna/equality/ChangeDetector.kt
new file mode 100644
index 0000000..6665133
--- /dev/null
+++ b/src/main/kotlin/com/kylecorry/luna/equality/ChangeDetector.kt
@@ -0,0 +1,6 @@
+package com.kylecorry.luna.equality
+
+interface ChangeDetector {
+    fun hasChanges(values: Array<out Any?>): Boolean
+    fun reset()
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/kylecorry/luna/equality/EqualityChangeDetector.kt b/src/main/kotlin/com/kylecorry/luna/equality/EqualityChangeDetector.kt
new file mode 100644
index 0000000..db98ff2
--- /dev/null
+++ b/src/main/kotlin/com/kylecorry/luna/equality/EqualityChangeDetector.kt
@@ -0,0 +1,44 @@
+package com.kylecorry.luna.equality
+
+class EqualityChangeDetector : ChangeDetector {
+
+    private val lock = Any()
+    private var cachedValues: MutableList<Any?>? = null
+
+    override fun hasChanges(values: Array<out Any?>): Boolean = synchronized(lock) {
+        var changed = false
+
+        val cached = if (cachedValues == null) {
+            cachedValues = mutableListOf()
+            changed = true
+            cachedValues
+        } else {
+            cachedValues
+        }!!
+
+        if (cached.size != values.size) {
+            values.forEachIndexed { index, value ->
+                if (index >= cached.size) {
+                    cached.add(value)
+                } else {
+                    cached[index] = value
+                }
+            }
+            changed = true
+        } else {
+            values.forEachIndexed { index, value ->
+                if (value != cached[index]) {
+                    cached[index] = value
+                    changed = true
+                }
+            }
+        }
+
+        return changed
+    }
+
+    override fun reset() = synchronized(lock) {
+        cachedValues = null
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/kylecorry/luna/hash/HashChangeDetector.kt b/src/main/kotlin/com/kylecorry/luna/equality/HashChangeDetector.kt
similarity index 82%
rename from src/main/kotlin/com/kylecorry/luna/hash/HashChangeDetector.kt
rename to src/main/kotlin/com/kylecorry/luna/equality/HashChangeDetector.kt
index e8136b5..24b77c7 100644
--- a/src/main/kotlin/com/kylecorry/luna/hash/HashChangeDetector.kt
+++ b/src/main/kotlin/com/kylecorry/luna/equality/HashChangeDetector.kt
@@ -1,11 +1,11 @@
-package com.kylecorry.luna.hash
+package com.kylecorry.luna.equality
 
-class HashChangeDetector {
+class HashChangeDetector: ChangeDetector {
 
     private val lock = Any()
     private var cachedHashes: MutableList<Int>? = null
 
-    fun hasChanges(values: Array<out Any?>): Boolean = synchronized(lock) {
+    override fun hasChanges(values: Array<out Any?>): Boolean = synchronized(lock) {
         var changed = false
 
         val cached = if (cachedHashes == null) {
@@ -38,7 +38,7 @@ class HashChangeDetector {
         return changed
     }
 
-    fun reset() = synchronized(lock) {
+    override fun reset() = synchronized(lock) {
         cachedHashes = null
     }
 
diff --git a/src/main/kotlin/com/kylecorry/luna/hash/HashUtils.kt b/src/main/kotlin/com/kylecorry/luna/equality/HashUtils.kt
similarity index 85%
rename from src/main/kotlin/com/kylecorry/luna/hash/HashUtils.kt
rename to src/main/kotlin/com/kylecorry/luna/equality/HashUtils.kt
index 9ebadfb..aafc351 100644
--- a/src/main/kotlin/com/kylecorry/luna/hash/HashUtils.kt
+++ b/src/main/kotlin/com/kylecorry/luna/equality/HashUtils.kt
@@ -1,4 +1,4 @@
-package com.kylecorry.luna.hash
+package com.kylecorry.luna.equality
 
 object HashUtils {
 
diff --git a/src/main/kotlin/com/kylecorry/luna/hooks/Effect.kt b/src/main/kotlin/com/kylecorry/luna/hooks/Effect.kt
index e83ddd9..8dbec45 100644
--- a/src/main/kotlin/com/kylecorry/luna/hooks/Effect.kt
+++ b/src/main/kotlin/com/kylecorry/luna/hooks/Effect.kt
@@ -1,6 +1,6 @@
 package com.kylecorry.luna.hooks
 
-import com.kylecorry.luna.hash.HashChangeDetector
+import com.kylecorry.luna.equality.EqualityChangeDetector
 
 /**
  * An effect that runs an action if the state has changed (similar to the effect hook in React)
@@ -8,7 +8,7 @@ import com.kylecorry.luna.hash.HashChangeDetector
 class Effect {
 
     private val lock = Any()
-    private val changeDetector = HashChangeDetector()
+    private val changeDetector = EqualityChangeDetector()
 
     /**
      * Run an action if the values have changed
diff --git a/src/main/kotlin/com/kylecorry/luna/hooks/MemoizedValue.kt b/src/main/kotlin/com/kylecorry/luna/hooks/MemoizedValue.kt
index 4395bea..abab4ac 100644
--- a/src/main/kotlin/com/kylecorry/luna/hooks/MemoizedValue.kt
+++ b/src/main/kotlin/com/kylecorry/luna/hooks/MemoizedValue.kt
@@ -1,11 +1,11 @@
 package com.kylecorry.luna.hooks
 
-import com.kylecorry.luna.hash.HashChangeDetector
+import com.kylecorry.luna.equality.EqualityChangeDetector
 
 class MemoizedValue<T> {
 
     private var cachedValue: T? = null
-    private val changeDetector = HashChangeDetector()
+    private val changeDetector = EqualityChangeDetector()
     private val lock = Any()
 
     fun getOrPut(vararg dependencies: Any?, value: () -> T): T = synchronized(lock) {