Mojo C++ bindings: support mapping mojo string to WTF::String.

The generator now supports a "--for_blink" flag. When it is specified, the generator will map mojo string to WTF::String.

BUG=583738

Review URL: https://codereview.chromium.org/1751563002

Cr-Commit-Position: refs/heads/master@{#381091}


CrOS-Libchrome-Original-Commit: 791f9b24ca1758ced39235bda1a4e0411801309c

8 files changed, 41 insertions, 13 deletions

diff --git a/mojo/public/tools/bindings/generators/cpp_templates/interface_declaration.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/interface_declaration.tmpl
index dddbbd319e..76888c7908 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/interface_declaration.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/interface_declaration.tmpl
@@ -53,7 +53,7 @@ class {{interface.name}} {
   }
 {%-     endif %}
 
-  using {{method.name}}Callback = {{interface_macros.declare_callback(method)}};
+  using {{method.name}}Callback = {{interface_macros.declare_callback(method, for_blink)}};
 {%-   endif %}
   virtual void {{method.name}}({{interface_macros.declare_request_params("", method)}}) = 0;
 {%- endfor %}
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/interface_macros.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/interface_macros.tmpl
index b00b1dad5a..f6056e80e0 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/interface_macros.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/interface_macros.tmpl
@@ -5,13 +5,13 @@
 {%-   endfor %}
 {%- endmacro %}
 
-{%- macro declare_callback(method) -%}
+{%- macro declare_callback(method, for_blink) -%}
 mojo::Callback<void(
 {%-   for param in method.response_parameters -%}
 {#- TODO(yzshen): Previously |cpp_result_type| is used here incorrectly.
     The outcome is we will use mojo::String instead of const mojo::String&.
     Preserve the behavior temporarily. #}
-{%- if not param.kind|is_string_kind -%}
+{%- if (not param.kind|is_string_kind) or for_blink -%}
 {{param.kind|cpp_const_wrapper_type}}
 {%- else -%}
 mojo::String
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/module.cc.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/module.cc.tmpl
index 8c9c0fb076..4d1dc90eec 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/module.cc.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/module.cc.tmpl
@@ -36,6 +36,10 @@
 #include "mojo/public/cpp/bindings/lib/validation_util.h"
 #include "mojo/public/interfaces/bindings/interface_control_messages.mojom.h"
 
+{%- if for_blink %}
+#include "mojo/public/cpp/bindings/lib/wtf_serialization.h"
+{%- endif %}
+
 {%- for namespace in namespaces_as_array %}
 namespace {{namespace}} {
 {%- endfor %}
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
index af93b8455c..8046116eb9 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
@@ -32,13 +32,17 @@
 #include "mojo/public/cpp/bindings/map.h"
 #include "mojo/public/cpp/bindings/message_filter.h"
 #include "mojo/public/cpp/bindings/no_interface.h"
-#include "mojo/public/cpp/bindings/string.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
 #include "mojo/public/cpp/bindings/struct_traits.h"
 #include "{{variant_path}}-internal.h"
 {%- for import in imports %}
 #include "{{import.module.path}}.h"
 {%- endfor %}
+{%- if not for_blink %}
+#include "mojo/public/cpp/bindings/string.h"
+{%- else %}
+#include "third_party/WebKit/Source/wtf/text/WTFString.h"
+{%- endif %}
 
 {%- for namespace in namespaces_as_array %}
 namespace {{namespace}} {
diff --git a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
index c2d3a1c3d8..44337403ab 100644
--- a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
@@ -42,9 +42,10 @@ _kind_to_cpp_literal_suffix = {
   mojom.UINT64:       "ULL",
 }
 
-# TODO(rockot): Get rid of this global. This requires some refactoring of the
+# TODO(rockot): Get rid of these globals. This requires some refactoring of the
 # generator library code so that filters can use the generator as context.
 _current_typemap = {}
+_for_blink = False
 
 
 def ConstantValue(constant):
@@ -56,9 +57,10 @@ def DefaultValue(field):
       assert field.default == "default"
       return "%s::New()" % GetNameForKind(field.kind)
     return ExpressionToText(field.default, kind=field.kind)
-  if (mojom.IsStringKind(field.kind) or mojom.IsArrayKind(field.kind) or
-      mojom.IsMapKind(field.kind)):
+  if mojom.IsArrayKind(field.kind) or mojom.IsMapKind(field.kind):
     return "nullptr";
+  if mojom.IsStringKind(field.kind):
+    return "" if _for_blink else "nullptr"
   return ""
 
 def NamespaceToArray(namespace):
@@ -187,7 +189,7 @@ def GetCppArrayArgWrapperType(kind):
     raise Exception("Arrays of associated interface requests not yet "
                     "supported!")
   if mojom.IsStringKind(kind):
-    return "mojo::String"
+    return "WTF::String" if _for_blink else "mojo::String"
   if mojom.IsGenericHandleKind(kind):
     return "mojo::ScopedHandle"
   if mojom.IsDataPipeConsumerKind(kind):
@@ -223,7 +225,7 @@ def GetCppResultWrapperType(kind):
   if mojom.IsAssociatedInterfaceRequestKind(kind):
     return "%sAssociatedRequest" % GetNameForKind(kind.kind)
   if mojom.IsStringKind(kind):
-    return "mojo::String"
+    return "WTF::String" if _for_blink else "mojo::String"
   if mojom.IsGenericHandleKind(kind):
     return "mojo::ScopedHandle"
   if mojom.IsDataPipeConsumerKind(kind):
@@ -265,7 +267,7 @@ def GetCppWrapperType(kind):
   if mojom.IsAssociatedInterfaceRequestKind(kind):
     return "%sAssociatedRequest" % GetNameForKind(kind.kind)
   if mojom.IsStringKind(kind):
-    return "mojo::String"
+    return "WTF::String" if _for_blink else "mojo::String"
   if mojom.IsGenericHandleKind(kind):
     return "mojo::ScopedHandle"
   if mojom.IsDataPipeConsumerKind(kind):
@@ -301,7 +303,7 @@ def GetCppConstWrapperType(kind):
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
   if mojom.IsStringKind(kind):
-    return "const mojo::String&"
+    return "const WTF::String&" if _for_blink else "const mojo::String&"
   if mojom.IsGenericHandleKind(kind):
     return "mojo::ScopedHandle"
   if mojom.IsDataPipeConsumerKind(kind):
@@ -525,6 +527,7 @@ class Generator(generator.Generator):
       "interfaces": self.GetInterfaces(),
       "variant": self.variant,
       "extra_headers": self.GetExtraHeaders(),
+      "for_blink": self.for_blink,
     }
 
   @staticmethod
@@ -550,6 +553,8 @@ class Generator(generator.Generator):
   def GenerateFiles(self, args):
     global _current_typemap
     _current_typemap = self.typemap
+    global _for_blink
+    _for_blink = self.for_blink
     suffix = "-%s" % self.variant if self.variant else ""
     self.Write(self.GenerateModuleHeader(),
         self.MatchMojomFilePath("%s%s.h" % (self.module.name, suffix)))
diff --git a/mojo/public/tools/bindings/mojom.gni b/mojo/public/tools/bindings/mojom.gni
index d8923dd146..9ff1af1265 100644
--- a/mojo/public/tools/bindings/mojom.gni
+++ b/mojo/public/tools/bindings/mojom.gni
@@ -59,6 +59,9 @@ mojom_generator_sources = [
 #   testonly (optional)
 #
 #   visibility (optional)
+#
+#   for_blink (optional, C++ only)
+#       Use WTF types as generated type for mojo string/array/map.
 template("mojom") {
   assert(
       defined(invoker.sources) || defined(invoker.deps) ||
@@ -158,6 +161,10 @@ template("mojom") {
         }
         inputs += invoker.typemaps
       }
+
+      if (defined(invoker.for_blink) && invoker.for_blink) {
+        args += [ "--for_blink" ]
+      }
     }
   }
 
@@ -245,6 +252,9 @@ template("mojom") {
         full_name = get_label_info(d, "label_no_toolchain")
         deps += [ "${full_name}_${cpp_sources_suffix}" ]
       }
+      if (defined(invoker.for_blink) && invoker.for_blink) {
+        public_deps += [ "//mojo/public/cpp/bindings:wtf_support" ]
+      }
     }
   }
 
diff --git a/mojo/public/tools/bindings/mojom_bindings_generator.py b/mojo/public/tools/bindings/mojom_bindings_generator.py
index 18b9496daf..130e730abc 100755
--- a/mojo/public/tools/bindings/mojom_bindings_generator.py
+++ b/mojo/public/tools/bindings/mojom_bindings_generator.py
@@ -143,7 +143,8 @@ class MojomProcessor(object):
       for language, generator_module in generator_modules.iteritems():
         generator = generator_module.Generator(
             module, args.output_dir, typemap=self._typemap.get(language, {}),
-            variant=args.variant, bytecode_path=args.bytecode_path)
+            variant=args.variant, bytecode_path=args.bytecode_path,
+            for_blink=args.for_blink)
         filtered_args = []
         if hasattr(generator_module, 'GENERATOR_PREFIX'):
           prefix = '--' + generator_module.GENERATOR_PREFIX + '_'
@@ -252,6 +253,9 @@ def main():
           "the path from which to load template bytecode; to generate template "
           "bytecode, run %s precompile BYTECODE_PATH" % os.path.basename(
               sys.argv[0])))
+  generate_parser.add_argument("--for_blink", action="store_true",
+                               help="Use WTF types as generated types for mojo "
+                               "string/array/map.")
   generate_parser.set_defaults(func=_Generate)
 
   precompile_parser = subparsers.add_parser("precompile",
diff --git a/mojo/public/tools/bindings/pylib/mojom/generate/generator.py b/mojo/public/tools/bindings/pylib/mojom/generate/generator.py
index 0ecc615c18..a97d2eac3a 100644
--- a/mojo/public/tools/bindings/pylib/mojom/generate/generator.py
+++ b/mojo/public/tools/bindings/pylib/mojom/generate/generator.py
@@ -37,12 +37,13 @@ class Generator(object):
   # Pass |output_dir| to emit files to disk. Omit |output_dir| to echo all
   # files to stdout.
   def __init__(self, module, output_dir=None, typemap=None, variant=None,
-               bytecode_path=None):
+               bytecode_path=None, for_blink=False):
     self.module = module
     self.output_dir = output_dir
     self.typemap = typemap or {}
     self.variant = variant
     self.bytecode_path = bytecode_path
+    self.for_blink = for_blink
 
   def GetStructsFromMethods(self):
     result = []