Web MIDI: implement MIDIAccessPromise

Source/modules/webmidi/MIDIAccessPromise.cpp

Index: Source/modules/webmidi/MIDIAccessPromise.cpp
diff --git a/Source/modules/webmidi/MIDIAccessPromise.cpp b/Source/modules/webmidi/MIDIAccessPromise.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..44d22ced14bd76e02a5073b486d3c2d0b493f9fc
--- /dev/null
+++ b/Source/modules/webmidi/MIDIAccessPromise.cpp
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * 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
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "modules/webmidi/MIDIAccessPromise.h"
+
+#include "core/dom/DOMError.h"
+#include "modules/webmidi/MIDIAccess.h"
+#include "modules/webmidi/MIDIErrorCallback.h"
+#include "modules/webmidi/MIDISuccessCallback.h"
+
+namespace WebCore {
+
+PassRefPtr<MIDIAccessPromise> MIDIAccessPromise::create(ScriptExecutionContext* context, const Dictionary& options)
+{
+    RefPtr<MIDIAccessPromise> midiAccessPromise(adoptRef(new MIDIAccessPromise(context, options)));
+    midiAccessPromise->suspendIfNeeded();
+    return midiAccessPromise.release();
+}
+
+MIDIAccessPromise::~MIDIAccessPromise()
+{
+    stop();
+}
+
+void MIDIAccessPromise::fulfill()
+{
+    if (m_state == Pending) {
+        if (m_successCallback) {
+            m_state = Invoked;
+            m_successCallback->handleEvent(m_access.release().leakRef(), m_options->sysexEnabled);
+            m_options.clear();
+        } else {
+            m_state = Accepted;
+        }
+    }
+    m_successCallback.clear();
+    m_errorCallback.clear();
+}
+
+void MIDIAccessPromise::reject(DOMError* error)
+{
+    if (m_state == Pending) {
+        if (m_errorCallback) {
+            m_state = Invoked;
+            m_errorCallback->handleEvent(error);
+        } else {
+            m_state = Rejected;
+            m_error = adoptRef(error);
+        }
+    }
+    m_successCallback.clear();
+    m_errorCallback.clear();
+}
+
+MIDIAccessPromise::MIDIAccessPromise(ScriptExecutionContext* context, const Dictionary& options)

[Chris Rogers, 2013/06/07 02:50:08]

nit: constructor should be near top of file just below create()

[Takashi Toyoshima, 2013/06/07 03:55:37]

Done.

+    : ActiveDOMObject(context)
+    , m_context(context)
+    , m_state(Pending)
+    , m_options(adoptPtr(new MIDIOptions(options)))
+    , m_access(MIDIAccess::create(m_context))

[Chris Rogers, 2013/06/07 02:50:08]

I think we will need to add an additional constructor argument for
MIDIAccess::create() passing in |this| (this MIDIAccessPromise) so that the
MIDIAccess will be able to callback to our accept() method (or reject()).  Using
this approach it will be very easy to get the implementation working quickly.

This can be a temporary/quick way to make this work, until you can implement the
PromiseResolver as you suggest in the FIXME below.  I think it makes sense to do
something simple and direct for now, and not worry too much about all the
complicated details of Promise.  Our goal is to get the MIDI API basically
working, and then we can refine and make the Promise API implementation complete
later.

[Takashi Toyoshima, 2013/06/07 03:55:37]

Done.

+{
+    // FIXME: Make MIDIAccess have PromiseResolver functions to call fulfill() and reject().
+    // MIDIAccess should start asynchronous operation to get an access permission to MIDI,
+    // and be ready for accessing MIDI ports, here.
+    ScriptWrappable::init(this);
+}
+
+void MIDIAccessPromise::then(PassRefPtr<MIDISuccessCallback> successCallback, PassRefPtr<MIDIErrorCallback> errorCallback)
+{
+    switch (m_state) {
+    case Accepted:
+        successCallback->handleEvent(m_access.release().leakRef(), m_options->sysexEnabled);
+        m_options.clear();
+        m_state = Invoked;
+        break;
+    case Rejected:
+        errorCallback->handleEvent(m_error.release().leakRef());
+        m_state = Invoked;
+        break;
+    case Pending:
+        m_successCallback = successCallback;
+        m_errorCallback = errorCallback;
+        break;
+    case Invoked:
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+} // namespace WebCore