Added deep copy to util.copyTo()

lib/util.js

@@ -178,13 +178,18 @@ exports.clone = function clone( data, deep )
  * destination argument is first to allow extending an object without using the
  * full-blown class system.
  *
+ * If a deep copy is not performed, all values will be copied by reference.
+ *
  * @param  {Object}   dest  destination object
  * @param  {Object}   src   source object
+ * @param  {boolean}  deep  perform deep copy (slower)
  *
  * @return  {Object}  dest
  */
-exports.copyTo = function( dest, src )
+exports.copyTo = function( dest, src, deep )
 {
+    deep = !!deep;
+
     var get, set, data;
 
     // sanity check
@@ -204,14 +209,18 @@ exports.copyTo = function( dest, src )
 
             if ( data.get || data.set )
             {
-                // define the property the slower way (only needed for
-                // getters/setters)
+                // Define the property the slower way (only needed for
+                // getters/setters). We don't have to worry about cloning in
+                // this case, since getters/setters are methods.
                 Object.defineProperty( dest, prop, data );
             }
             else
             {
-                // normal copy by reference
-                dest[ prop ] = src[ prop ];
+                // normal copy; cloned if deep, otherwise by reference
+                dest[ prop ] = ( deep )
+                    ? exports.clone( src[ prop ], true )
+                    : src[ prop ]
+                ;
             }
         }
     }
@@ -220,7 +229,11 @@ exports.copyTo = function( dest, src )
     {
         for ( prop in src )
         {
-            dest[ prop ] = src[ prop ];
+            // normal copy; cloned if deep, otherwise by reference
+            dest[ prop ] = ( deep )
+                ? exports.clone( src[ prop ], true )
+                : src[ prop ]
+            ;
         }
     }
 

test/test-util-copy.js

@@ -142,3 +142,24 @@ var common = require( './common' ),
     }, TypeError, "Src parameter is required to be an object" );
 } )();
 
+
+/**
+ * For convenience, let's support a deep copy as well, just in case they don't
+ * want to copy everything by reference.
+ */
+( function testCanDeepCopy()
+{
+    var src  = { foo: [ 1, 2, 3 ] },
+        dest = copyTo( {}, src, true );
+
+    // copied values should be equal by value...
+    assert.deepEqual( src.val, dest.val,
+        "Copied values should be comparitively equal with deep copy"
+    );
+
+    // ...but not by reference
+    assert.ok( src.foo !== dest.foo,
+        "Copied values should not be the same object after deep copy"
+    );
+} )();
+