stdlib: Add clear and remove methods in AbstractMutableCollection

backend.native/tests/runtime/collections/AbstractMutableCollection.kt

@@ -0,0 +1,63 @@
+class TestCollection(): AbstractMutableCollection<Int>() {
+    companion object {
+        const val SIZE = 7
+    }
+
+    private val array = IntArray(SIZE)
+    private var len = 0
+
+    override val size: Int
+        get() = len
+
+    override fun add(element: Int): Boolean {
+        if (len >= SIZE) return false
+        array[len++] = element
+        return true
+    }
+
+    override fun iterator(): MutableIterator<Int> = object: MutableIterator<Int> {
+        var nextIndex = 0
+
+        override fun hasNext() = nextIndex < len
+        override fun next() = array[nextIndex++]
+
+        override fun remove() {
+            if (nextIndex == 0) throw IllegalStateException()
+            for (i in nextIndex..len - 1) {
+                array[i - 1] = array[i]
+            }
+            len--
+            nextIndex--
+        }
+    }
+
+    override fun clear() {
+        len = 0
+    }
+
+}
+
+fun assertEquals(a: TestCollection, b: List<Int>) {
+    if (a.size != b.size) {
+        throw AssertionError()
+    }
+    val aIt = a.iterator()
+    val bIt = b.iterator()
+    while (aIt.hasNext()) {
+        if (aIt.next() != bIt.next()) throw AssertionError("TestCollection contains wrong elements. Expected: $b, actual: $a.")
+    }
+}
+
+fun main(args: Array<String>) {
+    val c = TestCollection()
+    if (!c.addAll(listOf(1, 2, 3, 2, 4, 5, 4))) throw AssertionError("addAll is false when it must be true.")
+    if (c.addAll(listOf(1, 2)) != false) throw AssertionError("addAll is true when it must be false.")
+    c.removeAll(listOf(1, 2))
+    assertEquals(c, listOf(3, 4, 5, 4))
+    c.retainAll(listOf(4, 5))
+    assertEquals(c, listOf(4, 5, 4))
+    c.remove(4)
+    assertEquals(c, listOf(5, 4))
+    c.clear()
+    assertEquals(c, listOf())
+}