LibWeb: Extract the TextEncoderCommon mixin to its own IDL file

Co-Authored-By: Tim Flynn <trflynn89@pm.me>

Libraries/LibWeb/CMakeLists.txt

@@ -243,6 +243,7 @@ set(SOURCES
     Editing/Internal/Algorithms.cpp
     Encoding/TextDecoder.cpp
     Encoding/TextEncoder.cpp
+    Encoding/TextEncoderCommon.cpp
     EntriesAPI/FileSystemEntry.cpp
     EventTiming/PerformanceEventTiming.cpp
     Fetch/Body.cpp

Libraries/LibWeb/Encoding/TextEncoder.cpp

@@ -106,11 +106,4 @@ TextEncoderEncodeIntoResult TextEncoder::encode_into(String const& source, GC::R
     return { read, written };
 }
 
-// https://encoding.spec.whatwg.org/#dom-textencoder-encoding
-FlyString const& TextEncoder::encoding()
-{
-    static FlyString const encoding = "utf-8"_fly_string;
-    return encoding;
-}
-
 }

Libraries/LibWeb/Encoding/TextEncoder.h

@@ -11,6 +11,7 @@
 #include <AK/RefCounted.h>
 #include <LibJS/Forward.h>
 #include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/Encoding/TextEncoderCommon.h>
 #include <LibWeb/Forward.h>
 #include <LibWeb/WebIDL/Buffers.h>
 #include <LibWeb/WebIDL/Types.h>
@@ -24,7 +25,9 @@ struct TextEncoderEncodeIntoResult {
 };
 
 // https://encoding.spec.whatwg.org/#textencoder
-class TextEncoder final : public Bindings::PlatformObject {
+class TextEncoder final
+    : public Bindings::PlatformObject
+    , public TextEncoderCommonMixin {
     WEB_PLATFORM_OBJECT(TextEncoder, Bindings::PlatformObject);
     GC_DECLARE_ALLOCATOR(TextEncoder);
 
@@ -36,8 +39,6 @@ public:
     GC::Ref<JS::Uint8Array> encode(String const& input) const;
     TextEncoderEncodeIntoResult encode_into(String const& source, GC::Root<WebIDL::BufferSource> const& destination) const;
 
-    static FlyString const& encoding();
-
 protected:
     // https://encoding.spec.whatwg.org/#dom-textencoder
     explicit TextEncoder(JS::Realm&);

Libraries/LibWeb/Encoding/TextEncoder.idl

@@ -1,7 +1,4 @@
-// https://encoding.spec.whatwg.org/#textencodercommon
-interface mixin TextEncoderCommon {
-    readonly attribute DOMString encoding;
-};
+#import <Encoding/TextEncoderCommon.idl>
 
 // https://encoding.spec.whatwg.org/#dictdef-textencoderencodeintoresult
 dictionary TextEncoderEncodeIntoResult {
@@ -17,4 +14,5 @@ interface TextEncoder {
     [NewObject] Uint8Array encode(optional USVString input = "");
     TextEncoderEncodeIntoResult encodeInto(USVString source, [AllowShared] Uint8Array destination);
 };
+
 TextEncoder includes TextEncoderCommon;

Libraries/LibWeb/Encoding/TextEncoderCommon.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Encoding/TextEncoderCommon.h>
+
+namespace Web::Encoding {
+
+TextEncoderCommonMixin::TextEncoderCommonMixin() = default;
+TextEncoderCommonMixin::~TextEncoderCommonMixin() = default;
+
+// https://encoding.spec.whatwg.org/#dom-textencoder-encoding
+FlyString const& TextEncoderCommonMixin::encoding() const
+{
+    // The encoding getter steps are to return "utf-8".
+    static FlyString const encoding = "utf-8"_fly_string;
+    return encoding;
+}
+
+}

Libraries/LibWeb/Encoding/TextEncoderCommon.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+
+namespace Web::Encoding {
+
+class TextEncoderCommonMixin {
+public:
+    virtual ~TextEncoderCommonMixin();
+
+    // https://encoding.spec.whatwg.org/#dom-textencoder-encoding
+    FlyString const& encoding() const;
+
+protected:
+    TextEncoderCommonMixin();
+};
+
+}

Libraries/LibWeb/Encoding/TextEncoderCommon.idl

@@ -0,0 +1,4 @@
+// https://encoding.spec.whatwg.org/#textencodercommon
+interface mixin TextEncoderCommon {
+    readonly attribute DOMString encoding;
+};