--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.ruby.nodes/src/com/oracle/truffle/ruby/nodes/core/ArrayIndexNode.java	Mon Jan 06 17:12:09 2014 +0000
@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2013 Oracle and/or its affiliates. All rights reserved. This
+ * code is released under a tri EPL/GPL/LGPL license. You can use it,
+ * redistribute it and/or modify it under the terms of the:
+ *
+ * Eclipse Public License version 1.0
+ * GNU General Public License version 2
+ * GNU Lesser General Public License version 2.1
+ */
+package com.oracle.truffle.ruby.nodes.core;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.dsl.*;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.ruby.nodes.*;
+import com.oracle.truffle.ruby.runtime.*;
+import com.oracle.truffle.ruby.runtime.core.array.*;
+
+/**
+ * Index an array, without using any method lookup. This isn't a call - it's an operation on a core
+ * class.
+ */
+@NodeInfo(shortName = "array-index")
+@NodeChildren({@NodeChild(value = "array", type = RubyNode.class)})
+public abstract class ArrayIndexNode extends RubyNode {
+
+    final int index;
+
+    public ArrayIndexNode(RubyContext context, SourceSection sourceSection, int index) {
+        super(context, sourceSection);
+        this.index = index;
+    }
+
+    public ArrayIndexNode(ArrayIndexNode prev) {
+        super(prev);
+        index = prev.index;
+    }
+
+    @Specialization(guards = "isEmptyStore", order = 1)
+    public NilPlaceholder indexEmpty(@SuppressWarnings("unused") RubyArray array) {
+        return NilPlaceholder.INSTANCE;
+    }
+
+    @Specialization(guards = "isFixnumStore", rewriteOn = UnexpectedResultException.class, order = 2)
+    public int indexFixnum(RubyArray array) throws UnexpectedResultException {
+        final FixnumArrayStore store = (FixnumArrayStore) array.getArrayStore();
+        return store.getFixnum(ArrayUtilities.normaliseIndex(store.size(), index));
+    }
+
+    @Specialization(guards = "isFixnumStore", order = 3)
+    public Object indexMaybeFixnum(RubyArray array) {
+        final FixnumArrayStore store = (FixnumArrayStore) array.getArrayStore();
+
+        try {
+            return store.getFixnum(ArrayUtilities.normaliseIndex(store.size(), index));
+        } catch (UnexpectedResultException e) {
+            return e.getResult();
+        }
+    }
+
+    @Specialization(guards = "isFixnumImmutablePairStore", rewriteOn = UnexpectedResultException.class, order = 4)
+    public int indexFixnumImmutablePair(RubyArray array) throws UnexpectedResultException {
+        final FixnumImmutablePairArrayStore store = (FixnumImmutablePairArrayStore) array.getArrayStore();
+        return store.getFixnum(ArrayUtilities.normaliseIndex(store.size(), index));
+    }
+
+    @Specialization(guards = "isFixnumImmutablePairStore", order = 5)
+    public Object indexMaybeFixnumImmutablePair(RubyArray array) {
+        final FixnumImmutablePairArrayStore store = (FixnumImmutablePairArrayStore) array.getArrayStore();
+
+        try {
+            return store.getFixnum(ArrayUtilities.normaliseIndex(store.size(), index));
+        } catch (UnexpectedResultException e) {
+            return e.getResult();
+        }
+    }
+
+    @Specialization(guards = "isObjectStore", order = 6)
+    public Object indexObject(RubyArray array) {
+        final ObjectArrayStore store = (ObjectArrayStore) array.getArrayStore();
+        return store.get(ArrayUtilities.normaliseIndex(store.size(), index));
+    }
+
+    @Specialization(guards = "isObjectImmutablePairStore", order = 7)
+    public Object indexObjectImmutablePair(RubyArray array) {
+        final ObjectImmutablePairArrayStore store = (ObjectImmutablePairArrayStore) array.getArrayStore();
+        return store.get(ArrayUtilities.normaliseIndex(store.size(), index));
+    }
+
+    protected boolean isEmptyStore(RubyArray receiver) {
+        return receiver.getArrayStore() instanceof EmptyArrayStore;
+    }
+
+    protected boolean isFixnumStore(RubyArray receiver) {
+        return receiver.getArrayStore() instanceof FixnumArrayStore;
+    }
+
+    protected boolean isFixnumImmutablePairStore(RubyArray receiver) {
+        return receiver.getArrayStore() instanceof FixnumImmutablePairArrayStore;
+    }
+
+    protected boolean isObjectStore(RubyArray receiver) {
+        return receiver.getArrayStore() instanceof ObjectArrayStore;
+    }
+
+    protected boolean isObjectImmutablePairStore(RubyArray receiver) {
+        return receiver.getArrayStore() instanceof ObjectImmutablePairArrayStore;
+    }
+
+}