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/*
* Copyright (c) 2022-2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/CharacterTypes.h>
#include <AK/Utf32View.h>
#include <AK/Utf8View.h>
#include <LibUnicode/CharacterTypes.h>
#include <LibUnicode/Emoji.h>
#if ENABLE_UNICODE_DATA
# include <LibUnicode/UnicodeData.h>
#endif
namespace Unicode {
Optional<Emoji> __attribute__((weak)) find_emoji_for_code_points(ReadonlySpan<u32>) { return {}; }
#if ENABLE_UNICODE_DATA
// https://unicode.org/reports/tr51/#def_emoji_core_sequence
static bool could_be_start_of_emoji_core_sequence(u32 code_point, Optional<u32> const& next_code_point)
{
// emoji_core_sequence := emoji_character | emoji_presentation_sequence | emoji_keycap_sequence | emoji_modifier_sequence | emoji_flag_sequence
static constexpr auto emoji_presentation_selector = 0xFE0Fu;
static constexpr auto combining_enclosing_keycap = 0x20E3u;
// https://unicode.org/reports/tr51/#def_emoji_keycap_sequence
// emoji_keycap_sequence := [0-9#*] \x{FE0F 20E3}
if (is_ascii_digit(code_point) || code_point == '#' || code_point == '*')
return next_code_point == emoji_presentation_selector || next_code_point == combining_enclosing_keycap;
// A little non-standard, but all other ASCII code points are not the beginning of any emoji sequence.
if (is_ascii(code_point))
return false;
// https://unicode.org/reports/tr51/#def_emoji_character
if (code_point_has_property(code_point, Property::Emoji))
return true;
// https://unicode.org/reports/tr51/#def_emoji_presentation_sequence
// emoji_presentation_sequence := emoji_character emoji_presentation_selector
if (next_code_point == emoji_presentation_selector)
return true;
// https://unicode.org/reports/tr51/#def_emoji_modifier_sequence
// emoji_modifier_sequence := emoji_modifier_base emoji_modifier
if (code_point_has_property(code_point, Property::Emoji_Modifier_Base))
return true;
// https://unicode.org/reports/tr51/#def_emoji_flag_sequence
// emoji_flag_sequence := regional_indicator regional_indicator
if (code_point_has_property(code_point, Property::Regional_Indicator))
return true;
return false;
}
static bool could_be_start_of_serenity_emoji(u32 code_point)
{
// We use Supplementary Private Use Area-B for custom Serenity emoji, starting at U+10CD00.
static constexpr auto first_custom_serenity_emoji_code_point = 0x10CD00u;
return code_point >= first_custom_serenity_emoji_code_point;
}
#endif
// https://unicode.org/reports/tr51/#def_emoji_sequence
template<typename CodePointIterator>
static bool could_be_start_of_emoji_sequence_impl(CodePointIterator const& it)
{
// emoji_sequence := emoji_core_sequence | emoji_zwj_sequence | emoji_tag_sequence
if (it.done())
return false;
#if ENABLE_UNICODE_DATA
// The purpose of this method is to quickly filter out code points that cannot be the start of
// an emoji. The emoji_core_sequence definition alone captures the start of all possible
// emoji_zwj_sequence and emoji_tag_sequence emojis, because:
//
// * emoji_zwj_sequence must begin with emoji_zwj_element, which is:
// emoji_zwj_sequence := emoji_core_sequence | emoji_tag_sequence
//
// * emoji_tag_sequence must begin with tag_base, which is:
// tag_base := emoji_character | emoji_modifier_sequence | emoji_presentation_sequence
// Note that this is a subset of emoji_core_sequence.
auto code_point = *it;
auto next_code_point = it.peek(1);
if (could_be_start_of_emoji_core_sequence(code_point, next_code_point))
return true;
if (could_be_start_of_serenity_emoji(code_point))
return true;
return false;
#else
return true;
#endif
}
bool could_be_start_of_emoji_sequence(Utf8CodePointIterator const& it)
{
return could_be_start_of_emoji_sequence_impl(it);
}
bool could_be_start_of_emoji_sequence(Utf32CodePointIterator const& it)
{
return could_be_start_of_emoji_sequence_impl(it);
}
}
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