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();
+}
+
+MIDIAccessPromise::MIDIAccessPromise(ScriptExecutionContext* context, const Dictionary& options)
+    : ActiveDOMObject(context)
+    , m_context(context)
+    , m_state(Pending)
+    , m_options(adoptPtr(new MIDIOptions(options)))
+{
+    ScriptWrappable::init(this);
+}
+
+void MIDIAccessPromise::then(PassRefPtr<MIDISuccessCallback> successCallback, PassRefPtr<MIDIErrorCallback> errorCallback)
+{
+    switch (m_state) {
+    case Accepted:
+        successCallback->handleEvent(MIDIAccess::create(m_context).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;

[Chris Rogers, 2013/06/06 17:02:24]

This is where we need to make the request to the MIDI system to get permission. 
We can iterate this part in later CLs 

For now, we at least need to add a // FIXME comment to explain this

The simplest way is to create the MIDIAccess right here:

m_access = MIDIAccess::create(m_context, this);

then the MIDIAccess will make the request and callback to
MIDIAccessPromise::accept()   ... or reject()

[Takashi Toyoshima, 2013/06/07 02:06:56]

Agreed on adding comments and create the MIDIAccess right now, but I think it's
not here, but in constructor, right?
Asynchronous operation should start even if then() is not called.

+        break;
+    case Invoked:
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void MIDIAccessPromise::accept()
+{
+    if (m_state == Pending) {
+        if (m_successCallback) {
+            m_state = Invoked;
+            m_successCallback->handleEvent(MIDIAccess::create(m_context).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();
+}
+
+} // namespace WebCore