Added MRUCache

src/commonTest/kotlin/bintools/TestTools.kt

@@ -1,7 +1,11 @@
 package bintools
 
+import net.sergeych.bintools.MRUCache
 import net.sergeych.bintools.toDump
 import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
 
 class TestTools {
     @Test
@@ -16,4 +20,42 @@ class TestTools {
             println(res.toDump())
         }
     }
+
+    @Test
+    fun testCache() {
+        val cache = MRUCache<Int,String>(3)
+        cache.putAll( mapOf(1 to "one", 2 to "two", 3 to "three", 4 to "four" ) )
+        assertNull(cache[0])
+
+        // this actually should reset MRU for 2:
+        assertEquals("two", cache[2])
+        assertNull(cache[1])
+        assertEquals(3, cache.size)
+        assertTrue { 3 in cache }
+        assertTrue { 4 in cache }
+
+    // now MRU is 2 (checked in assertEquals above) so LRU to drop is 3!
+        cache[5] = "five"
+        assertEquals(3, cache.size)
+        assertTrue { 2 in cache }
+        assertTrue { 4 in cache }
+        assertTrue { 5 in cache }
+
+        cache.getOrPut(3) { "new three"}
+        assertEquals(3, cache.size)
+        assertTrue { 2 in cache }
+        assertTrue { 3 in cache }
+        assertTrue { 5 in cache }
+
+        cache[2] = "New Two"
+        cache[6] = "six"
+
+        // 2 is now second used
+        // amd 6 is MRU, oldest is therefore 5
+
+        assertEquals(3, cache.size)
+        assertTrue { 2 in cache }
+        assertTrue { 6 in cache }
+        assertTrue { 3 in cache }
+    }
 }