IntersectionObserver: second cut.

third_party/WebKit/Source/bindings/core/v8/custom/V8IntersectionObserverCustom.cpp

+// Copyright 2015 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/V8IntersectionObserver.h"
+
+#include "bindings/core/v8/ExceptionMessages.h"
+#include "bindings/core/v8/ExceptionState.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8DOMWrapper.h"
+#include "bindings/core/v8/V8GCController.h"
+#include "bindings/core/v8/V8IntersectionObserverCallback.h"
+#include "bindings/core/v8/V8IntersectionObserverInit.h"
+
+namespace blink {
+
+void V8IntersectionObserver::constructorCustom(const v8::FunctionCallbackInfo<v8::Value>& info)
+{
+    if (UNLIKELY(info.Length() < 1)) {
+        V8ThrowException::throwException(createMinimumArityTypeErrorForMethod(info.GetIsolate(), "createIntersectionObserver", "Intersection", 1, info.Length()), info.GetIsolate());
+        return;
+    }
+
+    v8::Local<v8::Object> wrapper = info.Holder();
+
+    if (!info[0]->IsFunction()) {
+        V8ThrowException::throwTypeError(info.GetIsolate(), ExceptionMessages::failedToExecute("createIntersectionObserver", "Intersection", "The callback provided as parameter 1 is not a function."));
+        return;
+    }
+
+    if (info.Length() > 1 && !isUndefinedOrNull(info[1]) && !info[1]->IsObject()) {
+        V8ThrowException::throwTypeError(info.GetIsolate(), ExceptionMessages::failedToExecute("createIntersectionObserver", "Intersection", "IntersectionObserverInit (parameter 2) is not an object."));
+        return;
+    }
+
+    IntersectionObserverInit intersectionObserverInit;
+    ExceptionState exceptionState(ExceptionState::ConstructionContext, "Intersection", info.Holder(), info.GetIsolate());
+    V8IntersectionObserverInit::toImpl(info.GetIsolate(), info[1], intersectionObserverInit, exceptionState);
+    if (exceptionState.hadException()) {
+        V8ThrowException::throwGeneralError(info.GetIsolate(), exceptionState.message());
+        return;
+    }
+
+    IntersectionObserverCallback* callback = new V8IntersectionObserverCallback(v8::Local<v8::Function>::Cast(info[0]), wrapper, ScriptState::current(info.GetIsolate()));
+    IntersectionObserver* observer = IntersectionObserver::create(intersectionObserverInit, *callback, exceptionState);

[haraken, 2015/12/22 01:13:29]

I think you can just pass callback instead of *callback.

[esprehn, 2015/12/22 07:50:32]

*callback signifies that it's not null to the ::create() method.

[szager1, 2015/12/22 07:53:40]

Previous comment from esprehn@ suggested this parameter should be a reference
rather than a pointer, since it can never be null.

+    if (!observer || exceptionState.hadException()) {
+        V8ThrowException::throwGeneralError(info.GetIsolate(), exceptionState.message());

[haraken, 2015/12/22 01:13:29]

Why do you need this GeneralError?

When writing custom bindings, please copy & paste auto-generated code and modify
only the part you really need to modify.

[szager1, 2015/12/22 07:53:40]

IntersectionObserver::create will return NULL and set an exception in
exceptionState if it encounters an error.  Is there a better way to propagate
the error to v8?

+        return;
+    }
+
+    v8SetReturnValue(info, V8DOMWrapper::associateObjectWithWrapper(info.GetIsolate(), observer, &wrapperTypeInfo, wrapper));
+}
+
+} // namespace blink