Add equality change detector

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()
+}

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
+    }
+
+}

src/main/kotlin/com/kylecorry/luna/hash/HashChangeDetector.kt → 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
     }
 

src/main/kotlin/com/kylecorry/luna/hash/HashUtils.kt → 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 {
 

src/main/kotlin/com/kylecorry/luna/hooks/Effect.kt

@@ -1,14 +1,14 @@
 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)
  */
 class Effect {
 
     private val lock = Any()
-    private val changeDetector = HashChangeDetector()
+    private val changeDetector = EqualityChangeDetector()
 
     /**
      * Run an action if the values have changed

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) {