jruby · Nov 21, 2015 · Nov 21, 2015 · Nov 21, 2015
diff --git a/core/src/main/java/org/jruby/RubyArray.java b/core/src/main/java/org/jruby/RubyArray.java
@@ -81,7 +81,6 @@
 import static org.jruby.RubyEnumerator.enumeratorize;
 import static org.jruby.RubyEnumerator.enumeratorizeWithSize;
 import static org.jruby.runtime.Helpers.invokedynamic;
-import static org.jruby.runtime.Helpers.memchr;
 import static org.jruby.runtime.Visibility.PRIVATE;
 import static org.jruby.runtime.invokedynamic.MethodNames.HASH;
 import static org.jruby.runtime.invokedynamic.MethodNames.OP_CMP;
@@ -4097,6 +4096,16 @@ public RubyString pack(ThreadContext context, IRubyObject obj) {
         }
     }
 
+    @JRubyMethod(name = "dig", required = 1, rest = true)
+    public IRubyObject dig(ThreadContext context, IRubyObject[] args) {
+        return dig(context, args, 0);
+    }
+
+    final IRubyObject dig(ThreadContext context, IRubyObject[] args, int idx) {
+        final IRubyObject val = at( args[idx++] );
+        return idx == args.length ? val : RubyObject.dig(context, val, args, idx);
+    }
+
     @Override
     public Class getJavaClass() {
         return List.class;

diff --git a/core/src/main/java/org/jruby/RubyHash.java b/core/src/main/java/org/jruby/RubyHash.java
@@ -1932,6 +1932,16 @@ public IRubyObject getIfNone(){
         return ifNone;
     }
 
+    @JRubyMethod(name = "dig", required = 1, rest = true)
+    public IRubyObject dig(ThreadContext context, IRubyObject[] args) {
+        return dig(context, args, 0);
+    }
+
+    final IRubyObject dig(ThreadContext context, IRubyObject[] args, int idx) {
+        final IRubyObject val = op_aref( context, args[idx++] );
+        return idx == args.length ? val : RubyObject.dig(context, val, args, idx);
+    }
+
     private static class VisitorIOException extends RuntimeException {
         VisitorIOException(Throwable cause) {
             super(cause);

diff --git a/core/src/main/java/org/jruby/RubyObject.java b/core/src/main/java/org/jruby/RubyObject.java
@@ -537,6 +537,31 @@ public static RubyString inspect(ThreadContext context, IRubyObject object) {
         return str;
     }
 
+    // MRI: rb_obj_dig
+    static IRubyObject dig(ThreadContext context, IRubyObject obj, IRubyObject[] args, int idx) {
+        if ( obj.isNil() ) return context.nil;
+        if ( obj instanceof RubyArray ) {
+            return ((RubyArray) obj).dig(context, args, idx);
+        }
+        if ( obj instanceof RubyHash ) {
+            return ((RubyHash) obj).dig(context, args, idx);
+        }
+        if ( obj.respondsTo("dig") ) {
+            final int len = args.length - idx;
+            switch ( len ) {
+                case 1:
+                    return obj.callMethod(context, "dig", args[idx]);
+                case 2:
+                    return obj.callMethod(context, "dig", new IRubyObject[] { args[idx], args[idx+1] });
+                default:
+                    IRubyObject[] rest = new IRubyObject[len];
+                    System.arraycopy(args, idx, rest, 0, len);
+                    return obj.callMethod(context, "dig", rest);
+            }
+        }
+        return context.nil; // can not dig further (there's still args left)
+    }
+
     /**
      * Tries to support Java serialization of Ruby objects. This is
      * still experimental and might not work.

diff --git a/spec/truffle/tags/core/array/dig_tags.txt b/spec/truffle/tags/core/array/dig_tags.txt
@@ -0,0 +1,3 @@
+fails:Array#dig returns #at with one arg
+fails:Array#dig recurses array elements
+fails:Array#dig raises without any args
diff --git a/spec/truffle/tags/core/hash/dig_tags.txt b/spec/truffle/tags/core/hash/dig_tags.txt
@@ -0,0 +1,4 @@
+fails:Hash#dig returns [] with one arg
+fails:Hash#dig does recurse
+fails:Hash#dig raises without args
+fails:Hash#dig handles type-mixed deep digging