binding: Introduces ExceptionToPromiseScope.

third_party/WebKit/Source/bindings/core/v8/GeneratedCodeHelper.cpp

 // Copyright 2016 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.
 
 #include "bindings/core/v8/GeneratedCodeHelper.h"
 
+#include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/SerializedScriptValue.h"
 #include "bindings/core/v8/V8Binding.h"
 
 namespace blink {
 
 void v8ConstructorAttributeGetter(v8::Local<v8::Name> propertyName, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     v8::Local<v8::Value> data = info.Data();
     DCHECK(data->IsExternal());
     V8PerContextData* perContextData = V8PerContextData::from(info.Holder()->CreationContext());
     if (!perContextData)
         return;
     v8SetReturnValue(info, perContextData->constructorForType(WrapperTypeInfo::unwrap(data)));
 }
 
 v8::Local<v8::Value> v8Deserialize(v8::Isolate* isolate, PassRefPtr<SerializedScriptValue> value)
 {
     if (value)
         return value->deserialize();
     return v8::Null(isolate);
 }
 
+void throwMinimumArityError(ExceptionState& exceptionState, unsigned expected, unsigned actual)

[haraken, 2016/09/02 16:24:13]

These helper functions are just one line, so I'd prefer inlining them in the
call sites.

Even if we want to have the helper functions, I want to avoid putting it in
GeneratedCodeHelper since it's used in hand-written bindings as well. (I still
don't understand what GeneratedCodeHelper is.)

[Yuki, 2016/09/05 07:19:25]

I think we'd like to guarantee the following things.
- Arity error is a TypeError.
- The error message is the same among all APIs.

These helpers are useful to make sure of those things.
Do you think V8XxxCustom.cpp is out of scope?

Otherwise, all the clients are generated bindings, and no one in core/ or
modules/ use these helpers, or I don't expect such use cases in future.

[haraken, 2016/09/05 08:24:22]

I don't know. Even if we adopt your definition of generated bindings, I don't
see much benefit of distinguishing helper classes for generated bindings vs.
non-generated bindings.

Tangentically related, but Onion Soup is going to move core/modules-independent
parts of bindings/ into platform/.

+{
+    exceptionState.throwTypeError(ExceptionMessages::notEnoughArguments(expected, actual));
+}
+
+void throwInvalidArityError(ExceptionState& exceptionState, const char* validRange, unsigned actual)
+{
+    exceptionState.throwTypeError(ExceptionMessages::invalidArity(validRange, actual));
+}
+
+void throwMinimumArityErrorForMethod(v8::Isolate* isolate, const char* interface, const char* method, unsigned expected, unsigned actual)
+{
+    V8ThrowException::throwTypeError(isolate, ExceptionMessages::failedToExecute(method, interface, ExceptionMessages::notEnoughArguments(expected, actual)));
+}
+
+void throwMinimumArityErrorForConstructor(v8::Isolate* isolate, const char* interface, unsigned expected, unsigned actual)
+{
+    V8ThrowException::throwTypeError(isolate, ExceptionMessages::failedToConstruct(interface, ExceptionMessages::notEnoughArguments(expected, actual)));
+}
+
 } // namespace blink