LibWeb: Implement the CompressionStream interface

Author: https://github.com/trflynn89
Commit: 638a8aecad
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2370

Libraries/LibWeb/Compression/CompressionStream.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/MemoryStream.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/Variant.h>
+#include <LibCompress/Forward.h>
+#include <LibGC/Ptr.h>
+#include <LibJS/Forward.h>
+#include <LibWeb/Bindings/CompressionStreamPrototype.h>
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/Streams/GenericTransformStream.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+
+namespace Web::Compression {
+
+using Compressor = Variant<
+    NonnullOwnPtr<Compress::ZlibCompressor>,
+    NonnullOwnPtr<Compress::DeflateCompressor>,
+    NonnullOwnPtr<Compress::GzipCompressor>>;
+
+// https://compression.spec.whatwg.org/#compressionstream
+class CompressionStream final
+    : public Bindings::PlatformObject
+    , public Streams::GenericTransformStreamMixin {
+    WEB_PLATFORM_OBJECT(CompressionStream, Bindings::PlatformObject);
+    GC_DECLARE_ALLOCATOR(CompressionStream);
+
+public:
+    static WebIDL::ExceptionOr<GC::Ref<CompressionStream>> construct_impl(JS::Realm&, Bindings::CompressionFormat);
+    virtual ~CompressionStream() override;
+
+private:
+    CompressionStream(JS::Realm&, GC::Ref<Streams::TransformStream>, Compressor, NonnullOwnPtr<AllocatingMemoryStream>);
+
+    virtual void initialize(JS::Realm&) override;
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    WebIDL::ExceptionOr<void> compress_and_enqueue_chunk(JS::Value);
+    WebIDL::ExceptionOr<void> compress_flush_and_enqueue();
+
+    enum class Finish {
+        No,
+        Yes,
+    };
+    ErrorOr<ByteBuffer> compress(ReadonlyBytes, Finish);
+
+    Compressor m_compressor;
+    NonnullOwnPtr<AllocatingMemoryStream> m_output_stream;
+};
+
+}