LibTextCodec: Implement euc-kr encoder

Implements the `euc-kr` encoder, as specified by
https://encoding.spec.whatwg.org/#euc-kr-encoder

Meta/Lagom/Tools/CodeGenerators/LibTextCodec/GenerateEncodingIndexes.cpp

@@ -270,7 +270,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             { "big5"sv, prepare_table(data.get("big5"sv)->as_array(), GenerateAccessor::Yes) },
             { "jis0208"sv, prepare_table(data.get("jis0208"sv)->as_array(), GenerateAccessor::Yes, GenerateInverseAccessor::Yes) },
             { "jis0212"sv, prepare_table(data.get("jis0212"sv)->as_array(), GenerateAccessor::Yes) },
-            { "euc_kr"sv, prepare_table(data.get("euc-kr"sv)->as_array(), GenerateAccessor::Yes) },
+            { "euc_kr"sv, prepare_table(data.get("euc-kr"sv)->as_array(), GenerateAccessor::Yes, GenerateInverseAccessor::Yes) },
             { "ibm866"sv, prepare_table(data.get("ibm866"sv)->as_array()) },
             { "iso_8859_2"sv, prepare_table(data.get("iso-8859-2"sv)->as_array()) },
             { "iso_8859_3"sv, prepare_table(data.get("iso-8859-3"sv)->as_array()) },

Tests/LibTextCodec/TestTextEncoders.cpp

@@ -43,3 +43,21 @@ TEST_CASE(test_euc_jp_encoder)
     EXPECT(processed_bytes[3] == 0xA5);
     EXPECT(processed_bytes[4] == 0xC4);
 }
+
+TEST_CASE(test_euc_kr_encoder)
+{
+    TextCodec::EUCKREncoder encoder;
+    // U+B29F Hangul Syllable Neulh
+    // U+7C97 CJK Unified Ideograph-7C97
+    auto test_string = "\U0000B29F\U00007C97"sv;
+
+    Vector<u8> processed_bytes;
+    MUST(encoder.process(Utf8View(test_string), [&](u8 byte) {
+        return processed_bytes.try_append(byte);
+    }));
+    EXPECT(processed_bytes.size() == 4);
+    EXPECT(processed_bytes[0] == 0x88);
+    EXPECT(processed_bytes[1] == 0x6B);
+    EXPECT(processed_bytes[2] == 0xF0);
+    EXPECT(processed_bytes[3] == 0xD8);
+}

Userland/Libraries/LibTextCodec/Encoder.cpp

@@ -15,6 +15,7 @@ namespace TextCodec {
 namespace {
 UTF8Encoder s_utf8_encoder;
 EUCJPEncoder s_euc_jp_encoder;
+EUCKREncoder s_euc_kr_encoder;
 }
 
 Optional<Encoder&> encoder_for_exact_name(StringView encoding)
@@ -23,6 +24,8 @@ Optional<Encoder&> encoder_for_exact_name(StringView encoding)
         return s_utf8_encoder;
     if (encoding.equals_ignoring_ascii_case("euc-jp"sv))
         return s_euc_jp_encoder;
+    if (encoding.equals_ignoring_ascii_case("euc-kr"sv))
+        return s_euc_kr_encoder;
     dbgln("TextCodec: No encoder implemented for encoding '{}'", encoding);
     return {};
 }
@@ -100,4 +103,39 @@ ErrorOr<void> EUCJPEncoder::process(Utf8View input, Function<ErrorOr<void>(u8)>
     return {};
 }
 
+// https://encoding.spec.whatwg.org/#euc-kr-encoder
+ErrorOr<void> EUCKREncoder::process(Utf8View input, Function<ErrorOr<void>(u8)> on_byte)
+{
+    for (u32 item : input) {
+        // 1. If code point is end-of-queue, return finished.
+
+        // 2. If code point is an ASCII code point, return a byte whose value is code point.
+        if (is_ascii(item)) {
+            TRY(on_byte(static_cast<u8>(item)));
+            continue;
+        }
+
+        // 3. Let pointer be the index pointer for code point in index EUC-KR.
+        auto pointer = code_point_euc_kr_index(item);
+
+        // 4. If pointer is null, return error with code point.
+        if (!pointer.has_value()) {
+            // TODO: Report error.
+            continue;
+        }
+
+        // 5. Let lead be pointer / 190 + 0x81.
+        auto lead = *pointer / 190 + 0x81;
+
+        // 6. Let trail be pointer % 190 + 0x41.
+        auto trail = *pointer % 190 + 0x41;
+
+        // 7. Return two bytes whose values are lead and trail.
+        TRY(on_byte(static_cast<u8>(lead)));
+        TRY(on_byte(static_cast<u8>(trail)));
+    }
+
+    return {};
+}
+
 }

Userland/Libraries/LibTextCodec/Encoder.h

@@ -29,6 +29,11 @@ public:
     virtual ErrorOr<void> process(Utf8View, Function<ErrorOr<void>(u8)> on_byte) override;
 };
 
+class EUCKREncoder final : public Encoder {
+public:
+    virtual ErrorOr<void> process(Utf8View, Function<ErrorOr<void>(u8)> on_byte) override;
+};
+
 Optional<Encoder&> encoder_for_exact_name(StringView encoding);
 Optional<Encoder&> encoder_for(StringView label);