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f8a0365002
This was preventing some unqualified emoji sequences from rendering
properly, such as the custom SerenityOS flag. We rendered the flag
correctly when given the fully qualified sequence:
U+1F3F3 U+FEOF U+200D U+1F41E
But were not detecting the unqualified sequence as an emoji when also
filtering for emoji-presentation sequences:
U+1F3F3 U+200D U+1F41E
126 lines
4.5 KiB
C++
126 lines
4.5 KiB
C++
/*
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* Copyright (c) 2022-2023, Tim Flynn <trflynn89@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/Utf32View.h>
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#include <AK/Utf8View.h>
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#include <LibUnicode/CharacterTypes.h>
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#include <LibUnicode/Emoji.h>
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#if ENABLE_UNICODE_DATA
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# include <LibUnicode/UnicodeData.h>
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#endif
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namespace Unicode {
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Optional<Emoji> __attribute__((weak)) find_emoji_for_code_points(ReadonlySpan<u32>) { return {}; }
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#if ENABLE_UNICODE_DATA
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// https://unicode.org/reports/tr51/#def_emoji_core_sequence
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static bool could_be_start_of_emoji_core_sequence(u32 code_point, Optional<u32> const& next_code_point, SequenceType type)
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{
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// emoji_core_sequence := emoji_character | emoji_presentation_sequence | emoji_keycap_sequence | emoji_modifier_sequence | emoji_flag_sequence
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static constexpr auto emoji_presentation_selector = 0xFE0Fu;
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static constexpr auto combining_enclosing_keycap = 0x20E3u;
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static constexpr auto zero_width_joiner = 0x200Du;
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// https://unicode.org/reports/tr51/#def_emoji_keycap_sequence
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// emoji_keycap_sequence := [0-9#*] \x{FE0F 20E3}
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if (is_ascii_digit(code_point) || code_point == '#' || code_point == '*')
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return next_code_point == emoji_presentation_selector || next_code_point == combining_enclosing_keycap;
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// A little non-standard, but all other ASCII code points are not the beginning of any emoji sequence.
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if (is_ascii(code_point))
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return false;
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// https://unicode.org/reports/tr51/#def_emoji_character
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switch (type) {
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case SequenceType::Any:
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if (code_point_has_property(code_point, Property::Emoji))
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return true;
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break;
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case SequenceType::EmojiPresentation:
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if (code_point_has_property(code_point, Property::Emoji_Presentation))
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return true;
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if (next_code_point == zero_width_joiner && code_point_has_property(code_point, Property::Emoji))
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return true;
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break;
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}
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// https://unicode.org/reports/tr51/#def_emoji_presentation_sequence
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// emoji_presentation_sequence := emoji_character emoji_presentation_selector
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if (next_code_point == emoji_presentation_selector)
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return true;
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// https://unicode.org/reports/tr51/#def_emoji_modifier_sequence
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// emoji_modifier_sequence := emoji_modifier_base emoji_modifier
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if (code_point_has_property(code_point, Property::Emoji_Modifier_Base))
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return true;
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// https://unicode.org/reports/tr51/#def_emoji_flag_sequence
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// emoji_flag_sequence := regional_indicator regional_indicator
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if (code_point_has_property(code_point, Property::Regional_Indicator))
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return true;
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return false;
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}
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static bool could_be_start_of_serenity_emoji(u32 code_point)
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{
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// We use Supplementary Private Use Area-B for custom Serenity emoji, starting at U+10CD00.
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static constexpr auto first_custom_serenity_emoji_code_point = 0x10CD00u;
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return code_point >= first_custom_serenity_emoji_code_point;
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}
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#endif
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// https://unicode.org/reports/tr51/#def_emoji_sequence
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template<typename CodePointIterator>
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static bool could_be_start_of_emoji_sequence_impl(CodePointIterator const& it, [[maybe_unused]] SequenceType type)
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{
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// emoji_sequence := emoji_core_sequence | emoji_zwj_sequence | emoji_tag_sequence
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if (it.done())
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return false;
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#if ENABLE_UNICODE_DATA
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// The purpose of this method is to quickly filter out code points that cannot be the start of
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// an emoji. The emoji_core_sequence definition alone captures the start of all possible
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// emoji_zwj_sequence and emoji_tag_sequence emojis, because:
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//
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// * emoji_zwj_sequence must begin with emoji_zwj_element, which is:
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// emoji_zwj_element := emoji_core_sequence | emoji_tag_sequence
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//
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// * emoji_tag_sequence must begin with tag_base, which is:
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// tag_base := emoji_character | emoji_modifier_sequence | emoji_presentation_sequence
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// Note that this is a subset of emoji_core_sequence.
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auto code_point = *it;
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auto next_code_point = it.peek(1);
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if (could_be_start_of_emoji_core_sequence(code_point, next_code_point, type))
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return true;
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if (could_be_start_of_serenity_emoji(code_point))
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return true;
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return false;
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#else
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return true;
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#endif
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}
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bool could_be_start_of_emoji_sequence(Utf8CodePointIterator const& it, SequenceType type)
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{
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return could_be_start_of_emoji_sequence_impl(it, type);
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}
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bool could_be_start_of_emoji_sequence(Utf32CodePointIterator const& it, SequenceType type)
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{
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return could_be_start_of_emoji_sequence_impl(it, type);
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}
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}
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