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

Source/bindings/scripts/v8_methods.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 22 matching lines @@
 Design doc: http://www.chromium.org/developers/design-documents/idl-compiler
 """
 
 from idl_types import IdlType, IdlUnionType, inherits_interface
 from v8_globals import includes
 import v8_types
 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
     idl_type = method.idl_type
     is_static = method.is_static
     name = method.name
 
     idl_type.add_includes_for_type()
     this_cpp_value = cpp_value(interface, method, len(arguments))
 
@@ skipping 19 matching lines @@
         includes.add('core/dom/custom/CustomElementCallbackDispatcher.h')
 
     has_event_listener_argument = any(
         argument for argument in arguments
         if argument.idl_type.name == 'EventListener')
     is_check_security_for_frame = (
         'CheckSecurity' in interface.extended_attributes and
         '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,
         'deprecate_as': v8_utilities.deprecate_as(method),  # [DeprecateAs]
         'do_not_check_signature': not(is_static or
             v8_utilities.has_extended_attribute(method,
                 ['DoNotCheckSecurity', 'DoNotCheckSignature', 'NotEnumerable',
                  'ReadOnly', 'RuntimeEnabled', 'Unforgeable'])),
         'function_template': function_template(),
         'idl_type': idl_type.base_type,
@@ skipping 34 matching lines @@
         'property_attributes': property_attributes(method),
         'runtime_enabled_function': v8_utilities.runtime_enabled_function_name(method),  # [RuntimeEnabled]
         'signature': 'v8::Local<v8::Signature>()' if is_static or 'DoNotCheckSignature' in extended_attributes else 'defaultSignature',
         'union_arguments': idl_type.union_arguments,
         '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),
         'world_suffixes': ['', 'ForMainWorld'] if 'PerWorldBindings' in extended_attributes else [''],  # [PerWorldBindings]
     }
 
 
-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,
         'has_event_listener_argument': any(
             argument_so_far for argument_so_far in method.arguments[:index]
             if argument_so_far.idl_type.name == 'EventListener'),
         'has_type_checking_interface':
             (has_extended_attribute_value(interface, 'TypeChecking', 'Interface') or
              has_extended_attribute_value(method, 'TypeChecking', 'Interface')) and
             idl_type.is_wrapper_type,
         'has_type_checking_unrestricted':
             (has_extended_attribute_value(interface, 'TypeChecking', 'Unrestricted') or
              has_extended_attribute_value(method, 'TypeChecking', 'Unrestricted')) and
             idl_type.name in ('Float', 'Double'),
         # Dictionary is special-cased, but arrays and sequences shouldn't be
         'idl_type': not idl_type.array_or_sequence_type and idl_type.base_type,
         'idl_type_object': idl_type,
         'index': index,
         'is_clamp': 'Clamp' in extended_attributes,
         'is_callback_interface': idl_type.is_callback_interface,
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'vector_type': v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type),
         'is_wrapper_type': idl_type.is_wrapper_type,
         '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),
     }
 
 
 ################################################################################
 # Value handling
 ################################################################################
 
 def cpp_value(interface, method, number_of_arguments):
     def cpp_argument(argument):
         idl_type = argument.idl_type
@@ skipping 50 matching lines @@
     if (has_extended_attribute_value(method, 'CallWith', 'ScriptState') or
         'RaisesException' in extended_attributes or
         idl_type.is_union_type):
         cpp_value = 'result'  # use local variable for value
         release = idl_type.release
 
     script_wrappable = 'impl' if inherits_interface(interface_name, 'Node') else ''
     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'):
         v8_value = 'argumentOrNull(info, %s)' % 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)
 
 
 ################################################################################
 # Auxiliary functions
 ################################################################################
 
 # [NotEnumerable]
 def property_attributes(method):
     extended_attributes = method.extended_attributes
     property_attributes_list = []
     if 'NotEnumerable' in extended_attributes:
         property_attributes_list.append('v8::DontEnum')
     if 'ReadOnly' in extended_attributes:
         property_attributes_list.append('v8::ReadOnly')
     if property_attributes_list:
         property_attributes_list.insert(0, 'v8::DontDelete')
     return property_attributes_list
 
 
 def union_arguments(idl_type):
     """Return list of ['result0Enabled', 'result0', 'result1Enabled', ...] for union types, for use in setting return value"""
     return [arg
             for i in range(len(idl_type.member_types))
             for arg in ['result%sEnabled' % i, 'result%s' % i]]
 
 IdlType.union_arguments = property(lambda self: None)
 IdlUnionType.union_arguments = property(union_arguments)