From a8a81342bb52c8f567ae2c6c5f34dfe85e399123 Mon Sep 17 00:00:00 2001
From: Grubre <ogrodowczykjakub@gmail.com>
Date: Wed, 30 Oct 2024 20:36:26 +0100
Subject: [PATCH] LibUnicode: Implement `to_fullwidth()` in String

The implementation uses the transliterator class from icu.
---
 AK/String.h                              |  1 +
 Userland/Libraries/LibUnicode/String.cpp | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/AK/String.h b/AK/String.h
index 9461d16e875..c10b3fbf296 100644
--- a/AK/String.h
+++ b/AK/String.h
@@ -101,6 +101,7 @@ public:
     ErrorOr<String> to_uppercase(Optional<StringView> const& locale = {}) const;
     ErrorOr<String> to_titlecase(Optional<StringView> const& locale = {}, TrailingCodePointTransformation trailing_code_point_transformation = TrailingCodePointTransformation::Lowercase) const;
     ErrorOr<String> to_casefold() const;
+    ErrorOr<String> to_fullwidth() const;
 
     [[nodiscard]] String to_ascii_lowercase() const;
     [[nodiscard]] String to_ascii_uppercase() const;
diff --git a/Userland/Libraries/LibUnicode/String.cpp b/Userland/Libraries/LibUnicode/String.cpp
index 2e37675ca28..c9810cd8d32 100644
--- a/Userland/Libraries/LibUnicode/String.cpp
+++ b/Userland/Libraries/LibUnicode/String.cpp
@@ -11,6 +11,7 @@
 #include <unicode/bytestream.h>
 #include <unicode/casemap.h>
 #include <unicode/stringoptions.h>
+#include <unicode/translit.h>
 
 // This file contains definitions of AK::String methods which require UCD data.
 
@@ -85,6 +86,21 @@ ErrorOr<String> String::to_titlecase(Optional<StringView> const& locale, Trailin
     return builder.to_string_without_validation();
 }
 
+ErrorOr<String> String::to_fullwidth() const
+{
+    UErrorCode status = U_ZERO_ERROR;
+
+    auto const transliterator = adopt_own_if_nonnull(icu::Transliterator::createInstance("Halfwidth-Fullwidth", UTRANS_FORWARD, status));
+    if (Unicode::icu_failure(status)) {
+        return Error::from_string_literal("Unable to create transliterator");
+    }
+
+    auto icu_string = Unicode::icu_string(bytes_as_string_view());
+    transliterator->transliterate(icu_string);
+
+    return Unicode::icu_string_to_string(icu_string);
+}
+
 static ErrorOr<void> build_casefold_string(StringView string, StringBuilder& builder)
 {
     UErrorCode status = U_ZERO_ERROR;