Add field-initializing constructors to generated mojo structs.

mojo/public/tools/bindings/generators/mojom_cpp_generator.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generates C++ source files from a mojom.Module."""
 
 import mojom.generate.generator as generator
 import mojom.generate.module as mojom
 import mojom.generate.pack as pack
 from mojom.generate.template_expander import UseJinja
@@ skipping 464 matching lines @@
   for field in struct.fields:
     if IsMoveOnlyKind(field.kind):
       return True
   return False
 
 def ShouldInlineUnion(union):
   return not any(
       mojom.IsReferenceKind(field.kind) and not mojom.IsStringKind(field.kind)
            for field in union.fields)
 
+
+def GetNumConstructorParams(kind):
+  for i, field in enumerate(kind.fields):
+    # Types that are neither copyable nor movable can't be passed to a struct
+    # constructor so any constructors containing such a kind are skipped.
+    if (mojom.IsStructKind(field.kind) and IsTypemappedKind(field.kind) and

[yzshen1, 2017/02/14 17:21:53]

I think there is no need to check IsStructKind(), right? At least we should take
unions into account as well.

[Sam McNally, 2017/02/15 06:35:49]

Done.

+        _current_typemap[GetFullMojomNameForKind(field.kind)]["emplace_only"]):
+      return i
+  return len(kind.fields) + 1
+
+
 def GetContainerValidateParamsCtorArgs(kind):
   if mojom.IsStringKind(kind):
     expected_num_elements = 0
     element_is_nullable = False
     key_validate_params = "nullptr"
     element_validate_params = "nullptr"
     enum_validate_func = "nullptr"
   elif mojom.IsMapKind(kind):
     expected_num_elements = 0
     element_is_nullable = False
@@ skipping 69 matching lines @@
     "is_associated_kind": mojom.IsAssociatedKind,
     "is_hashable": IsHashableKind,
     "is_map_kind": mojom.IsMapKind,
     "is_nullable_kind": mojom.IsNullableKind,
     "is_object_kind": mojom.IsObjectKind,
     "is_reference_kind": mojom.IsReferenceKind,
     "is_string_kind": mojom.IsStringKind,
     "is_struct_kind": mojom.IsStructKind,
     "is_typemapped_kind": IsTypemappedKind,
     "is_union_kind": mojom.IsUnionKind,
+    "num_constructor_params": GetNumConstructorParams,
     "passes_associated_kinds": mojom.PassesAssociatedKinds,
     "stylize_method": generator.StudlyCapsToCamel,
     "under_to_camel": generator.UnderToCamel,
     "unmapped_type_for_serializer": GetUnmappedTypeForSerializer,
   }
 
   def GetExtraTraitsHeaders(self):
     extra_headers = set()
     for typemap in self._GetAllUsedTypemaps():
       extra_headers.update(typemap.get("traits_headers", []))
@@ skipping 145 matching lines @@
       global _use_once_callback
       _use_once_callback = self.use_once_callback
       global _variant
       _variant = self.variant
       suffix = "-%s" % self.variant if self.variant else ""
       self.Write(self.GenerateModuleHeader(),
                  self.MatchMojomFilePath("%s%s.h" % (self.module.name, suffix)))
       self.Write(
           self.GenerateModuleSource(),
           self.MatchMojomFilePath("%s%s.cc" % (self.module.name, suffix)))