initialize result variables in v8 bindings

Source/bindings/scripts/v8_types.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 102 matching lines @@
     'Promise': 'ScriptPromise',
     'ScriptValue': 'ScriptValue',
     # FIXME: Eliminate custom bindings for XPathNSResolver  http://crbug.com/345529
     'XPathNSResolver': 'RefPtrWillBeRawPtr<XPathNSResolver>',
     'boolean': 'bool',
     'unrestricted double': 'double',
     'unrestricted float': 'float',
 }
 
 
+def cpp_type_initializer(idl_type):
+    """Returns a string containing a C++ initialization statement for the
+    corresponding type.
+
+    |idl_type| argument is of type IdlType.
+    """
+
+    cpp_type = str(idl_type.cpp_type)
+
+    if (idl_type.base_type in (CPP_TYPE_SAME_AS_IDL_TYPE | CPP_INT_TYPES | CPP_UNSIGNED_TYPES) or
+        cpp_type in ('float', 'double') or

[haraken, 2014/07/16 00:54:02]

Can't we use idl_type.is_numeric_type() ?

[Mostyn Bramley-Moore, 2014/07/16 07:15:20]

Done.

+        cpp_type.endswith('*')):

[haraken, 2014/07/16 00:54:02]

Can this happen?

Actually we don't want to mix idl_type and cpp_type to judge the types. I think
this function should be written based on idl_type only.

[Jens Widell, 2014/07/16 07:00:53]

This is copied from my patch (which is unpolished) where the local is sometimes
of pointer type. Shouldn't be needed for this CL, and should probably be done
differently (based only on idl_type, as you say).

[Mostyn Bramley-Moore, 2014/07/16 07:15:20]

Done.

+        return ' = 0'
+    if cpp_type == 'bool':

[haraken, 2014/07/16 00:54:02]

idl_type.base_type == 'boolean'

[Mostyn Bramley-Moore, 2014/07/16 07:15:20]

Done.

+        return ' = false'
+    if cpp_type == 'String':
+        return ' = ""'

[haraken, 2014/07/16 00:54:02]

We shouldn't add this. A String should be initialized with a null string instead
of an empty string.

[Mostyn Bramley-Moore, 2014/07/16 07:15:20]

Done.

+    return ''
+
 def cpp_type(idl_type, extended_attributes=None, raw_type=False, used_as_argument=False, used_as_variadic_argument=False, used_in_cpp_sequence=False):
     """Returns C++ type corresponding to IDL type.
 
     |idl_type| argument is of type IdlType, while return value is a string
 
     Args:
         idl_type:
             IdlType
         raw_type:
             bool, True if idl_type's raw/primitive C++ type should be returned.
@@ skipping 608 matching lines @@
 
 def is_explicit_nullable(idl_type):
     # Nullable type that isn't implicit nullable (see above.) For such types,
     # we use Nullable<T> or similar explicit ways to represent a null value.
     return idl_type.is_nullable and not idl_type.is_implicit_nullable
 
 IdlType.is_implicit_nullable = property(is_implicit_nullable)
 IdlType.is_explicit_nullable = property(is_explicit_nullable)
 IdlUnionType.is_implicit_nullable = False
 IdlUnionType.is_explicit_nullable = property(is_explicit_nullable)