LibWeb: Add XMLHttpRequest object :^)

This patch adds very basic XMLHttpRequest support to LibWeb. Here's an
example that currently works:

    var callback = function() { alert(this.responseText); }
    var xhr = new XMLHttpRequest();
    xhr.addEventListener("load", callback);
    xhr.open("GET", "http://serenityos.org/~kling/test/example.txt");
    xhr.send();

There are many limitations and bugs, but it's pretty dang awesome that
we have XHR. :^)

1 files changed, 69 insertions, 0 deletions

diff --git a/Libraries/LibWeb/DOM/XMLHttpRequest.h b/Libraries/LibWeb/DOM/XMLHttpRequest.h
new file mode 100644
index 0000000000..f2924977aa
--- /dev/null
+++ b/Libraries/LibWeb/DOM/XMLHttpRequest.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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.
+ *
+ * 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 HOLDER 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.
+ */
+
+#pragma once
+
+#include <AK/ByteBuffer.h>
+#include <AK/RefCounted.h>
+#include <AK/Weakable.h>
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/DOM/EventTarget.h>
+
+namespace Web {
+
+class XMLHttpRequest final
+    : public RefCounted<XMLHttpRequest>
+    , public Weakable<XMLHttpRequest>
+    , public EventTarget
+    , public Bindings::Wrappable {
+public:
+    using WrapperType = Bindings::XMLHttpRequestWrapper;
+
+    static NonnullRefPtr<XMLHttpRequest> create() { return adopt(*new XMLHttpRequest); }
+
+    virtual ~XMLHttpRequest() override;
+
+    using RefCounted::ref;
+    using RefCounted::unref;
+
+    String response_text() const;
+    void open(const String& method, const String& url);
+    void send();
+
+private:
+    virtual void ref_event_target() override { ref(); }
+    virtual void unref_event_target() override { unref(); }
+    virtual void dispatch_event(NonnullRefPtr<Event>) override;
+
+    XMLHttpRequest();
+
+    String m_method;
+    String m_url;
+
+    ByteBuffer m_response;
+};
+
+}