Web MIDI: implement MIDIAccessPromise

Source/modules/webmidi/MIDIAccessPromise.cpp

+/*
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+ */
+
+#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