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AK: Add a String factory to create a string from a single code point

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This commit is contained in:
Timothy Flynn 2023-01-21 12:34:01 -05:00 committed by Linus Groh
parent 8aca8e82cb
commit 12c8bc3e85
2 changed files with 43 additions and 1 deletions
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19
AK/String.h
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@ -1,11 +1,13 @@
/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/CharacterTypes.h>
#include <AK/Concepts.h>
#include <AK/Format.h>
#include <AK/Forward.h>
@ -16,6 +18,7 @@
#include <AK/StringView.h>
#include <AK/Traits.h>
#include <AK/Types.h>
#include <AK/UnicodeUtils.h>
#include <AK/Vector.h>
namespace AK {
@ -74,6 +77,22 @@ public:
return String { short_string };
}
// Creates a new String from a single code point.
static constexpr String from_code_point(u32 code_point)
{
VERIFY(is_unicode(code_point));
ShortString short_string;
size_t i = 0;
auto length = UnicodeUtils::code_point_to_utf8(code_point, [&](auto byte) {
short_string.storage[i++] = static_cast<u8>(byte);
});
short_string.byte_count_and_short_string_flag = (length << 1) | SHORT_STRING_FLAG;
return String { short_string };
}
// Creates a new String by case-transforming this String. Using these methods require linking LibUnicode into your application.
ErrorOr<String> to_lowercase(Optional<StringView> const& locale = {}) const;
ErrorOr<String> to_uppercase(Optional<StringView> const& locale = {}) const;

25
Tests/AK/TestString.cpp
View File

@ -4,9 +4,12 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
// This is included first on purpose. We specifically do not want LibTest to override VERIFY here so
// that we can actually test that some String factory methods cause a crash with invalid input.
#include <AK/String.h>
#include <LibTest/TestCase.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>
#include <AK/Try.h>
#include <AK/Utf8View.h>
@ -64,6 +67,26 @@ TEST_CASE(long_strings)
EXPECT_EQ(string.bytes_as_string_view(), "abcdefgh"sv);
}
TEST_CASE(from_code_points)
{
for (u32 code_point = 0; code_point < 0x80; ++code_point) {
auto string = String::from_code_point(code_point);
auto ch = static_cast<char>(code_point);
StringView view { &ch, 1 };
EXPECT_EQ(string, view);
}
auto string = String::from_code_point(0x10ffff);
EXPECT_EQ(string, "\xF4\x8F\xBF\xBF"sv);
EXPECT_CRASH("Creating a string from an invalid code point", [] {
String::from_code_point(0xffffffff);
return Test::Crash::Failure::DidNotCrash;
});
}
TEST_CASE(substring)
{
auto superstring = MUST(String::from_utf8("Hello I am a long string"sv));