IDL: restructure logic handling registration of methods

Source/bindings/scripts/v8_interface.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 # coding=utf-8
 #
 # 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
@@ skipping 232 matching lines @@
         'has_constructor_attributes': any(attribute['constructor_type'] for attribute in attributes),
         'has_per_context_enabled_attributes': any(attribute['per_context_enabled_function'] for attribute in attributes),
         'has_replaceable_attributes': any(attribute['is_replaceable'] for attribute in attributes),
     })
 
     # Methods
     methods = [v8_methods.generate_method(interface, method)
                for method in interface.operations
                if method.name]  # Skip anonymous special operations (methods)
     generate_method_overloads(methods)
+
+    per_context_enabled_methods = []
+    custom_registration_methods = []
+    method_configuration_methods = []
+
     for method in methods:
-        method['do_generate_method_configuration'] = (
-            method['do_not_check_signature'] and
-            not method['per_context_enabled_function'] and
-            # For overloaded methods, only generate one accessor
-            ('overload_index' not in method or method['overload_index'] == 1))
+        # Skip all but one method in each set of overloaded methods.
+        if 'overload_index' in method and 'overloads' not in method:
+            continue
 
+        if 'overloads' in method:
+            overloads = method['overloads']
+            per_context_enabled_function = overloads['per_context_enabled_function_all']
+            runtime_enabled_function = overloads['runtime_enabled_function_all']
+            has_custom_registration = overloads['has_custom_registration_all']
+        else:
+            per_context_enabled_function = method['per_context_enabled_function']
+            runtime_enabled_function = method['runtime_enabled_function']
+            has_custom_registration = method['has_custom_registration']
+
+        if per_context_enabled_function:
+            per_context_enabled_methods.append(method)
+            continue
+        if runtime_enabled_function or has_custom_registration:
+            custom_registration_methods.append(method)
+            continue
+        method_configuration_methods.append(method)
+
+    for method in methods:
         # The value of the Function object’s “length” property is a Number
         # determined as follows:
         # 1. Let S be the effective overload set for regular operations (if the
         # operation is a regular operation) or for static operations (if the
         # operation is a static operation) with identifier id on interface I and
         # with argument count 0.
         # 2. Return the length of the shortest argument list of the entries in S.
         # FIXME: This calculation doesn't take into account whether runtime
         # enabled overloads are actually enabled, so length may be incorrect.
         # E.g., [RuntimeEnabled=Foo] void f(); void f(long x);
         # should have length 1 if Foo is not enabled, but length 0 if it is.
         method['length'] = (method['overloads']['minarg'] if 'overloads' in method else
                             method['number_of_required_arguments'])
 
     template_contents.update({
+        'custom_registration_methods': custom_registration_methods,
         'has_origin_safe_method_setter': any(
             method['is_check_security_for_frame'] and not method['is_read_only']
             for method in methods),
-        'has_method_configuration': any(method['do_generate_method_configuration'] for method in methods),
-        'has_per_context_enabled_methods': any(method['per_context_enabled_function'] for method in methods),
+        'method_configuration_methods': method_configuration_methods,
+        'per_context_enabled_methods': per_context_enabled_methods,
         'methods': methods,
     })
 
     template_contents.update({
         'indexed_property_getter': indexed_property_getter(interface),
         'indexed_property_setter': indexed_property_setter(interface),
         'indexed_property_deleter': indexed_property_deleter(interface),
         'is_override_builtins': 'OverrideBuiltins' in extended_attributes,
         'named_property_getter': named_property_getter(interface),
         'named_property_setter': named_property_setter(interface),
@@ skipping 86 matching lines @@
     # function object to an incorrect value when none of those overloads were
     # actually enabled at runtime. The exception is if all overloads are
     # controlled by the same runtime enabled feature, in which case there would
     # be no function object at all if it is not enabled.
     shortest_overloads = effective_overloads_by_length[0][1]
     if (all(method.get('runtime_enabled_function')
             for method, _, _ in shortest_overloads) and
         not common_value(overloads, 'runtime_enabled_function')):
         raise ValueError('Function.length of %s depends on runtime enabled features' % overloads[0]['name'])
 
+    # Check and fail if overloads disagree on any of the extended attributes
+    # that affect how the method should be registered.
+    # Skip the check for overloaded constructors, since they don't support any
+    # of the extended attributes in question.
+    if not overloads[0].get('is_constructor'):

[Nils Barth (inactive), 2014/06/11 10:10:28]

nit: Normally we'd combine these into a single boolean expression to reduce
nesting.
(However, if replace body with loop as suggested in next comment, then this is
fine.)

+        if (common_value(overloads, 'is_do_not_check_security') is None or

[Nils Barth (inactive), 2014/06/11 10:10:28]

This is a bit indirect and hence fragile, going via the context values;
could you instead directly test the extended attributes?
Something like:
overload_extended_attributes = [overload.extended_attributes for overload in
overloads]
for extended_attribute in v8_methods.CUSTOM_REGISTRATION_EXTENDED_ATTRIBUTES:
    if common_key(overload_extended_attributes, extended_attribute) is None:
        raise ValueError

...with an auxiliary common_key function which is just:
if all(key in dict for dict in dicts): return True
if all(key not in dict for dict in dicts)): return False
return None

How does this sound?

[Jens Widell, 2014/06/11 10:20:57]

Sounds good, except at this point I only have what is returned by
generate_method(), and that doesn't include the actual extended attributes.

I could make generate_method() include the extended attributes directly, but it
feels a bit ugly since (as I understand it) it's a design principle to not
expose the "raw" extended attributes to the templates. Other suggestions?

+            common_value(overloads, 'is_do_not_check_signature') is None or
+            common_value(overloads, 'property_attributes') is None):
+            raise ValueError('Overloads of %s have conflicting extended attributes' % overloads[0]['name'])

[Nils Barth (inactive), 2014/06/11 10:10:28]

Could you factor out a helper variable:
name = overloads[0]['name']
...at the top?

+
     return {
         'deprecate_all_as': common_value(overloads, 'deprecate_as'),  # [DeprecateAs]
         'length_tests_methods': length_tests_methods(effective_overloads_by_length),
         'minarg': lengths[0],
         # 1. Let maxarg be the length of the longest type list of the
         # entries in S.
         'maxarg': lengths[-1],
         'measure_all_as': common_value(overloads, 'measure_as'),  # [MeasureAs]
+        'has_custom_registration_all': common_value(overloads, 'has_custom_registration'),
+        'per_context_enabled_function_all': common_value(overloads, 'per_context_enabled_function'),  # [PerContextEnabled]
+        'runtime_enabled_function_all': common_value(overloads, 'runtime_enabled_function'),  # [RuntimeEnabled]
         'valid_arities': lengths
             # Only need to report valid arities if there is a gap in the
             # sequence of possible lengths, otherwise invalid length means
             # "not enough arguments".
             if lengths[-1] - lengths[0] != len(lengths) - 1 else None,
     }
 
 
 def effective_overload_set(F):
     """Returns the effective overload set of an overloaded function.
@@ skipping 629 matching lines @@
         deleter = next(
             method
             for method in interface.operations
             if ('deleter' in method.specials and
                 len(method.arguments) == 1 and
                 str(method.arguments[0].idl_type) == 'DOMString'))
     except StopIteration:
         return None
 
     return property_deleter(deleter)