Create fewer local v8::TryCatch objects in generated bindings code

Source/bindings/scripts/v8_methods.py

Index: Source/bindings/scripts/v8_methods.py
diff --git a/Source/bindings/scripts/v8_methods.py b/Source/bindings/scripts/v8_methods.py
index c6692831c1bb38d1743b68932a77f9928833d8dd..c3f3f8614bf46bee27319da841da0dfda5279dad 100644
--- a/Source/bindings/scripts/v8_methods.py
+++ b/Source/bindings/scripts/v8_methods.py
@@ -40,6 +40,22 @@ import v8_utilities
 from v8_utilities import has_extended_attribute_value
 
 
+def argument_needs_try_catch(argument):
+    idl_type = argument.idl_type
+    base_type = not idl_type.array_or_sequence_type and idl_type.base_type
+
+    return not (
+        # These cases are handled by separate code paths in the
+        # generate_argument() macro in Source/bindings/templates/methods.cpp.
+        idl_type.is_callback_interface or
+        base_type == 'SerializedScriptValue' or
+        (argument.is_variadic and idl_type.is_wrapper_type) or
+        # String and enumeration arguments converted using one of the
+        # TOSTRING_* macros in Source/bindings/v8/V8BindingMacros.h don't
+        # use a v8::TryCatch.
+        (base_type == 'DOMString' and not argument.is_variadic))

[haraken, 2014/05/21 14:56:45]

I'm a bit concerned that this list becomes out-dated. Then we will miss adding a
TryCatch block that is needed. (But I have no good idea to address the issue.)

[Jens Widell, 2014/05/21 15:07:02]

I'm a bit concerned about maintainability here as well, but can't think of a
better way to do it, and not doing it increases code size.

The case where we miss a TryCatch is at least very loud and clear: compilation
breaks. It would probably happen to someone changing this script. Worst case is
that some innocent IDL file change mysteriously breaks compilation (after
someone changed the script and forgot to keep this list updated.)

But, well, I can't think of anything better than this code right now, and think
it solves a problem that needs solving.

+
+
 def generate_method(interface, method):
     arguments = method.arguments
     extended_attributes = method.extended_attributes
@@ -79,10 +95,14 @@ def generate_method(interface, method):
         'DoNotCheckSecurity' not in extended_attributes)
     is_raises_exception = 'RaisesException' in extended_attributes
 
+    arguments_need_try_catch = any(argument_needs_try_catch(argument)
+                                   for argument in arguments)
+
     return {
         'activity_logging_world_list': v8_utilities.activity_logging_world_list(method),  # [ActivityLogging]
-        'arguments': [generate_argument(interface, method, argument, index)
+        'arguments': [generate_argument(interface, method, argument, index, arguments_need_try_catch)
                       for index, argument in enumerate(arguments)],
+        'arguments_need_try_catch': arguments_need_try_catch,
         'conditional_string': v8_utilities.conditional_string(method),
         'cpp_type': idl_type.cpp_type,
         'cpp_value': this_cpp_value,
@@ -137,14 +157,16 @@ def generate_method(interface, method):
     }
 
 
-def generate_argument(interface, method, argument, index):
+def generate_argument(interface, method, argument, index, method_has_try_catch):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
 
     return {
-        'cpp_type': idl_type.cpp_type_args(used_in_cpp_sequence=is_variadic_wrapper_type),
+        'cpp_type': idl_type.cpp_type_args(extended_attributes=extended_attributes,
+                                           used_as_argument=True,
+                                           used_as_variadic_argument=argument.is_variadic),
         'cpp_value': this_cpp_value,
         'enum_validation_expression': idl_type.enum_validation_expression,
         'has_default': 'Default' in extended_attributes,
@@ -173,7 +195,7 @@ def generate_argument(interface, method, argument, index):
         'name': argument.name,
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
-        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index),
+        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index, method_has_try_catch),
     }
 
 
@@ -244,15 +266,13 @@ def v8_set_return_value(interface_name, method, cpp_value, for_main_world=False)
     return idl_type.v8_set_return_value(cpp_value, extended_attributes, script_wrappable=script_wrappable, release=release, for_main_world=for_main_world)
 
 
-def v8_value_to_local_cpp_value(argument, index):
+def v8_value_to_local_cpp_value(argument, index, method_has_try_catch):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     name = argument.name
     if argument.is_variadic:
-        vector_type = v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type)
-        return 'TONATIVE_VOID({vector_type}<{cpp_type}>, {name}, toNativeArguments<{cpp_type}>(info, {index}))'.format(
-            vector_type=vector_type, cpp_type=idl_type.cpp_type, name=name,
-            index=index)
+        return 'TONATIVE_VOID_INTERNAL({name}, toNativeArguments<{cpp_type}>(info, {index}))'.format(
+            cpp_type=idl_type.cpp_type, name=name, index=index)
     # [Default=NullString]
     if (argument.is_optional and idl_type.name == 'String' and
         extended_attributes.get('Default') == 'NullString'):
@@ -260,7 +280,8 @@ def v8_value_to_local_cpp_value(argument, index):
     else:
         v8_value = 'info[%s]' % index
     return idl_type.v8_value_to_local_cpp_value(extended_attributes, v8_value,
-                                                name, index=index)
+                                                name, index=index, declare_variable=False,
+                                                method_has_try_catch=method_has_try_catch)
 
 
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