IDL: allow optional values to be undefined in overload resolution

Source/bindings/scripts/code_generator_v8.pm

 # Copyright (C) 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
 # Copyright (C) 2006 Anders Carlsson <andersca@mac.com>
 # Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
 # Copyright (C) 2006 Alexey Proskuryakov <ap@webkit.org>
 # Copyright (C) 2006 Apple Computer, Inc.
 # Copyright (C) 2007, 2008, 2009, 2012 Google Inc.
 # Copyright (C) 2009 Cameron McCormack <cam@mcc.id.au>
 # Copyright (C) Research In Motion Limited 2010. All rights reserved.
 # Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
 # Copyright (C) 2012 Ericsson AB. All rights reserved.
@@ skipping 2176 matching lines @@
     deleteHiddenValue(info.GetIsolate(), info.Holder(), "${attrName}"); // Invalidate the cached value.
 END
     }
 
     $code .= "}\n";  # end of setter
     $code .= "#endif // ${conditionalString}\n" if $conditionalString;
     $code .= "\n";
     $implementation{nameSpaceInternal}->add($code);
 }
 
+sub NullOrOptionalCheck
+{
+    my $parameter = shift;
+    my $value = shift;
+
+    # If undefined is passed for an optional argument, the argument should be
+    # treated as missing; otherwise undefined is not allowed.
+    if ($parameter->isNullable) {
+        if ($parameter->isOptional) {
+            return "isUndefinedOrNull($value)";
+        }
+        return "${value}->IsNull()";
+    }
+    if ($parameter->isOptional) {
+        return "${value}->IsUndefined()";
+    }
+}
+
 sub GenerateParametersCheckExpression
 {
     my $numParameters = shift;
     my $function = shift;
 
     my @andExpression = ();
     push(@andExpression, "info.Length() == $numParameters");
     my $parameterIndex = 0;
     foreach my $parameter (@{$function->parameters}) {
         last if $parameterIndex >= $numParameters;
         my $value = "info[$parameterIndex]";
         my $type = $parameter->type;
 
+        my $undefinedOrNullCheck = NullOrOptionalCheck($parameter, $value);
+
         # Only DOMString, wrapper types, and (to some degree) non-wrapper types
         # are checked.
         #
         # FIXME: If distinguishing non-primitive type from primitive type,
         # (e.g., sequence<DOMString> from DOMString or Dictionary from double)
         # the non-primitive type must appear *first* in the IDL file,
         # since we're not adding a check to primitive types.
         # This can be avoided if compute overloads for whole overload set at
         # once, rather than one method at a time, but that requires a complete
         # rewrite of this algorithm.
@@ skipping 18 matching lines @@
                 push(@andExpression, "${value}->IsArray()");
             }
         } elsif (IsWrapperType($type)) {
             if ($parameter->isNullable) {
                 push(@andExpression, "${value}->IsNull() || V8${type}::hasInstance($value, info.GetIsolate())");
             } else {
                 push(@andExpression, "V8${type}::hasInstance($value, info.GetIsolate())");
             }
         } elsif ($nonWrapperTypes{$type}) {
             # Non-wrapper types are just objects: we don't distinguish type
-            if ($parameter->isNullable) {
-                push(@andExpression, "${value}->IsNull() || ${value}->IsObject()");
+            if ($undefinedOrNullCheck) {
+                push(@andExpression, "$undefinedOrNullCheck || ${value}->IsObject()");
             } else {
                 push(@andExpression, "${value}->IsObject()");
             }
         }
 
         $parameterIndex++;
     }
     @andExpression = map { "($_)" } @andExpression;
     my $res = "(" . join(" && ", @andExpression) . ")";
     return $res;
@@ skipping 4167 matching lines @@
         if ($parameter->type eq "SerializedScriptValue") {
             return 1;
         } elsif (IsIntegerType($parameter->type)) {
             return 1;
         }
     }
     return 0;
 }
 
 1;