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https://github.com/RGBCube/serenity
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1393ed2000
We currently fully casefold the left- and right-hand sides to compare two strings with case-insensitivity. Now, we casefold one code point at a time, storing the result in a view for comparison, until we exhaust both strings.
101 lines
2.7 KiB
C++
101 lines
2.7 KiB
C++
/*
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* Copyright (c) 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/String.h>
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#include <AK/StringBuilder.h>
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#include <AK/Utf32View.h>
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#include <AK/Utf8View.h>
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#include <LibUnicode/UnicodeUtils.h>
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// This file contains definitions of AK::String methods which require UCD data.
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namespace AK {
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ErrorOr<String> String::to_lowercase(Optional<StringView> const& locale) const
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{
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StringBuilder builder;
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TRY(Unicode::Detail::build_lowercase_string(code_points(), builder, locale));
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return builder.to_string();
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}
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ErrorOr<String> String::to_uppercase(Optional<StringView> const& locale) const
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{
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StringBuilder builder;
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TRY(Unicode::Detail::build_uppercase_string(code_points(), builder, locale));
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return builder.to_string();
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}
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ErrorOr<String> String::to_titlecase(Optional<StringView> const& locale) const
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{
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StringBuilder builder;
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TRY(Unicode::Detail::build_titlecase_string(code_points(), builder, locale));
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return builder.to_string();
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}
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ErrorOr<String> String::to_casefold() const
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{
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StringBuilder builder;
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TRY(Unicode::Detail::build_casefold_string(code_points(), builder));
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return builder.to_string();
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}
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class CasefoldStringComparator {
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public:
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explicit CasefoldStringComparator(Utf8View string)
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: m_string(string)
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, m_it(m_string.begin())
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{
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}
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bool has_more_data() const
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{
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return !m_casefolded_code_points.is_empty() || (m_it != m_string.end());
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}
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u32 next_code_point()
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{
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VERIFY(has_more_data());
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if (m_casefolded_code_points.is_empty()) {
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m_current_code_point = *m_it;
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++m_it;
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m_casefolded_code_points = Unicode::Detail::casefold_code_point(m_current_code_point);
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VERIFY(!m_casefolded_code_points.is_empty()); // Must at least contain the provided code point.
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}
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auto code_point = m_casefolded_code_points[0];
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m_casefolded_code_points = m_casefolded_code_points.substring_view(1);
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return code_point;
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}
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private:
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Utf8View m_string;
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Utf8CodePointIterator m_it;
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u32 m_current_code_point { 0 };
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Utf32View m_casefolded_code_points;
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};
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// https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf#G34145
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bool String::equals_ignoring_case(String const& other) const
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{
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// A string X is a caseless match for a string Y if and only if:
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// toCasefold(X) = toCasefold(Y)
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CasefoldStringComparator lhs { code_points() };
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CasefoldStringComparator rhs { other.code_points() };
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while (lhs.has_more_data() && rhs.has_more_data()) {
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if (lhs.next_code_point() != rhs.next_code_point())
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return false;
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}
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return !lhs.has_more_data() && !rhs.has_more_data();
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}
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}
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