SmartList - efficient indexOf / contains

platform/util/src/com/intellij/util/SmartList.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -288,4 +288,41 @@ public class SmartList<E> extends AbstractList<E> implements RandomAccess {
       myElem = Arrays.copyOf(array, mySize);
     }
   }
+
+  @Override
+  public int indexOf(Object o) {
+    if (mySize == 0) {
+      return -1;
+    }
+    else if (mySize == 1) {
+      if (o == null) {
+        return myElem == null ? 0 : -1;
+      }
+      else {
+        return o.equals(myElem) ? 0 : -1;
+      }
+    }
+
+    Object[] array = (Object[])myElem;
+    if (o == null) {
+      for (int i = 0; i < mySize; i++) {
+        if (array[i] == null) {
+          return i;
+        }
+      }
+    }
+    else {
+      for (int i = 0; i < mySize; i++) {
+        if (o.equals(array[i])) {
+          return i;
+        }
+      }
+    }
+    return -1;
+  }
+
+  @Override
+  public boolean contains(Object o) {
+    return indexOf(o) >= 0;
+  }
 }

platform/util/testSrc/com/intellij/util/SmartListTest.java

@@ -39,7 +39,12 @@ public class SmartListTest {
     List<Integer> l = new SmartList<>();
     l.add(1);
     assertThat(l).hasSize(1);
-    assertThat(l.get(0).intValue()).isEqualTo(1);
+    assertThat(l.get(0)).isEqualTo(1);
+
+    assertThat(l.indexOf(1)).isEqualTo(0);
+    assertThat(l.indexOf(2)).isEqualTo(-1);
+    assertThat(l.contains(1)).isTrue();
+    assertThat(l.contains(2)).isFalse();
   }
 
   @Test
@@ -50,6 +55,13 @@ public class SmartListTest {
     assertThat(l).hasSize(2);
     assertThat(l.get(0)).isEqualTo(1);
     assertThat(l.get(1)).isEqualTo(2);
+
+    assertThat(l.indexOf(1)).isEqualTo(0);
+    assertThat(l.indexOf(2)).isEqualTo(1);
+    assertThat(l.contains(1)).isTrue();
+    assertThat(l.contains(2)).isTrue();
+    assertThat(l.indexOf(42)).isEqualTo(-1);
+    assertThat(l.contains(42)).isFalse();
   }
 
   @Test
@@ -257,4 +269,16 @@ public class SmartListTest {
     assertThat(l.toArray(new Integer[4])).containsExactly(0, null, null, null);
     assertThat(l.toArray()).containsExactly(0);
   }
+
+  @Test
+  public void testNullIndexOf() {
+    List<Integer> l = new SmartList<>();
+    l.add(null);
+    l.add(null);
+
+    assertThat(l.indexOf(null)).isEqualTo(0);
+    assertThat(l.contains(null)).isTrue();
+    assertThat(l.indexOf(42)).isEqualTo(-1);
+    assertThat(l.contains(42)).isFalse();
+  }
 }