AK: Add Utf16View::to_utf8 to convert the view to a UTF-8 AK::String

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/2eacc7aec1
Pull-request: https://github.com/SerenityOS/serenity/pull/16926

AK/Utf16View.cpp

@@ -82,6 +82,11 @@ u32 Utf16View::decode_surrogate_pair(u16 high_surrogate, u16 low_surrogate)
 }
 
 ErrorOr<DeprecatedString> Utf16View::to_deprecated_string(AllowInvalidCodeUnits allow_invalid_code_units) const
+{
+    return TRY(to_utf8(allow_invalid_code_units)).to_deprecated_string();
+}
+
+ErrorOr<String> Utf16View::to_utf8(AllowInvalidCodeUnits allow_invalid_code_units) const
 {
     StringBuilder builder;
 
@@ -105,7 +110,7 @@ ErrorOr<DeprecatedString> Utf16View::to_deprecated_string(AllowInvalidCodeUnits
             TRY(builder.try_append_code_point(code_point));
     }
 
-    return builder.build();
+    return builder.to_string();
 }
 
 size_t Utf16View::length_in_code_points() const

AK/Utf16View.h

@@ -12,6 +12,7 @@
 #include <AK/Forward.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
+#include <AK/String.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
 
@@ -76,6 +77,7 @@ public:
     };
 
     ErrorOr<DeprecatedString> to_deprecated_string(AllowInvalidCodeUnits = AllowInvalidCodeUnits::No) const;
+    ErrorOr<String> to_utf8(AllowInvalidCodeUnits = AllowInvalidCodeUnits::No) const;
 
     bool is_null() const { return m_code_units.is_null(); }
     bool is_empty() const { return m_code_units.is_empty(); }

Tests/AK/TestUtf16.cpp

@@ -7,7 +7,7 @@
 #include <LibTest/TestCase.h>
 
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/String.h>
 #include <AK/StringView.h>
 #include <AK/Types.h>
 #include <AK/Utf16View.h>
@@ -53,17 +53,17 @@ TEST_CASE(decode_utf8)
 TEST_CASE(encode_utf8)
 {
     {
-        DeprecatedString utf8_string("Привет, мир! 😀 γειά σου κόσμος こんにちは世界");
+        auto utf8_string = MUST(String::from_utf8("Привет, мир! 😀 γειά σου κόσμος こんにちは世界"sv));
         auto string = MUST(AK::utf8_to_utf16(utf8_string));
         Utf16View view { string };
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes)), utf8_string);
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::No)), utf8_string);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::Yes)), utf8_string);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::No)), utf8_string);
     }
     {
         auto encoded = Array { (u16)0xd83d };
         Utf16View view { encoded };
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes)), "\xed\xa0\xbd"sv);
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::No)), "\ufffd"sv);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::Yes)), "\xed\xa0\xbd"sv);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::No)), "\ufffd"sv);
     }
 }
 
@@ -269,14 +269,14 @@ TEST_CASE(substring_view)
         view = view.substring_view(7, 2);
 
         EXPECT(view.length_in_code_units() == 2);
-        EXPECT_EQ(MUST(view.to_deprecated_string()), "😀"sv);
+        EXPECT_EQ(MUST(view.to_utf8()), "😀"sv);
     }
     {
         Utf16View view { string };
         view = view.substring_view(7, 1);
 
         EXPECT(view.length_in_code_units() == 1);
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes)), "\xed\xa0\xbd"sv);
-        EXPECT_EQ(MUST(view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::No)), "\ufffd"sv);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::Yes)), "\xed\xa0\xbd"sv);
+        EXPECT_EQ(MUST(view.to_utf8(Utf16View::AllowInvalidCodeUnits::No)), "\ufffd"sv);
     }
 }