354 lines
11 KiB
C++
354 lines
11 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2022, Linus Groh <linusg@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/Utf16View.h>
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#include <AK/Utf8View.h>
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#include <LibJS/Runtime/AbstractOperations.h>
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#include <LibJS/Runtime/GlobalObject.h>
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#include <LibJS/Runtime/PrimitiveString.h>
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#include <LibJS/Runtime/PropertyKey.h>
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#include <LibJS/Runtime/ThrowableStringBuilder.h>
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#include <LibJS/Runtime/VM.h>
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#include <LibJS/Runtime/Value.h>
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namespace JS {
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PrimitiveString::PrimitiveString(PrimitiveString& lhs, PrimitiveString& rhs)
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: m_is_rope(true)
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, m_lhs(&lhs)
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, m_rhs(&rhs)
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{
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}
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PrimitiveString::PrimitiveString(String string)
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: m_utf8_string(move(string))
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{
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}
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PrimitiveString::PrimitiveString(DeprecatedString string)
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: m_deprecated_string(move(string))
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{
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}
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PrimitiveString::PrimitiveString(Utf16String string)
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: m_utf16_string(move(string))
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{
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}
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PrimitiveString::~PrimitiveString()
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{
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if (has_utf8_string())
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vm().string_cache().remove(*m_utf8_string);
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if (has_deprecated_string())
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vm().deprecated_string_cache().remove(*m_deprecated_string);
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}
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void PrimitiveString::visit_edges(Cell::Visitor& visitor)
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{
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Cell::visit_edges(visitor);
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if (m_is_rope) {
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visitor.visit(m_lhs);
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visitor.visit(m_rhs);
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}
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}
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bool PrimitiveString::is_empty() const
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{
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if (m_is_rope) {
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// NOTE: We never make an empty rope string.
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return false;
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}
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if (has_utf16_string())
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return m_utf16_string->is_empty();
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if (has_utf8_string())
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return m_utf8_string->is_empty();
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if (has_deprecated_string())
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return m_deprecated_string->is_empty();
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VERIFY_NOT_REACHED();
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}
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ThrowCompletionOr<String> PrimitiveString::utf8_string() const
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{
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auto& vm = this->vm();
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TRY(resolve_rope_if_needed());
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if (!has_utf8_string()) {
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if (has_deprecated_string())
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m_utf8_string = TRY_OR_THROW_OOM(vm, String::from_utf8(*m_deprecated_string));
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else if (has_utf16_string())
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m_utf8_string = TRY(m_utf16_string->to_utf8(vm));
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else
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VERIFY_NOT_REACHED();
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}
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return *m_utf8_string;
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}
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ThrowCompletionOr<StringView> PrimitiveString::utf8_string_view() const
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{
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(void)TRY(utf8_string());
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return m_utf8_string->bytes_as_string_view();
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}
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ThrowCompletionOr<DeprecatedString> PrimitiveString::deprecated_string() const
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{
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TRY(resolve_rope_if_needed());
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if (!has_deprecated_string()) {
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if (has_utf8_string())
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m_deprecated_string = m_utf8_string->to_deprecated_string();
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else if (has_utf16_string())
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m_deprecated_string = TRY(m_utf16_string->to_deprecated_string(vm()));
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else
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VERIFY_NOT_REACHED();
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}
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return *m_deprecated_string;
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}
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ThrowCompletionOr<Utf16String> PrimitiveString::utf16_string() const
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{
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TRY(resolve_rope_if_needed());
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if (!has_utf16_string()) {
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if (has_utf8_string()) {
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m_utf16_string = TRY(Utf16String::create(vm(), m_utf8_string->bytes_as_string_view()));
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} else {
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VERIFY(has_deprecated_string());
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m_utf16_string = TRY(Utf16String::create(vm(), *m_deprecated_string));
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}
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}
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return *m_utf16_string;
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}
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ThrowCompletionOr<Utf16View> PrimitiveString::utf16_string_view() const
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{
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(void)TRY(utf16_string());
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return m_utf16_string->view();
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}
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ThrowCompletionOr<Optional<Value>> PrimitiveString::get(VM& vm, PropertyKey const& property_key) const
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{
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if (property_key.is_symbol())
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return Optional<Value> {};
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if (property_key.is_string()) {
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if (property_key.as_string() == vm.names.length.as_string()) {
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auto length = TRY(utf16_string()).length_in_code_units();
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return Value(static_cast<double>(length));
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}
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}
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auto index = MUST_OR_THROW_OOM(canonical_numeric_index_string(vm, property_key, CanonicalIndexMode::IgnoreNumericRoundtrip));
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if (!index.is_index())
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return Optional<Value> {};
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auto str = TRY(utf16_string_view());
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auto length = str.length_in_code_units();
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if (length <= index.as_index())
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return Optional<Value> {};
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return create(vm, TRY(Utf16String::create(vm, str.substring_view(index.as_index(), 1))));
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}
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NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, Utf16String string)
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{
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if (string.is_empty())
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return vm.empty_string();
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if (string.length_in_code_units() == 1) {
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u16 code_unit = string.code_unit_at(0);
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if (is_ascii(code_unit))
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return vm.single_ascii_character_string(static_cast<u8>(code_unit));
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}
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return vm.heap().allocate_without_realm<PrimitiveString>(move(string));
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}
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NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, String string)
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{
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if (string.is_empty())
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return vm.empty_string();
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if (auto bytes = string.bytes_as_string_view(); bytes.length() == 1) {
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auto ch = static_cast<u8>(bytes[0]);
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if (is_ascii(ch))
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return vm.single_ascii_character_string(ch);
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}
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auto& string_cache = vm.string_cache();
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if (auto it = string_cache.find(string); it != string_cache.end())
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return *it->value;
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auto new_string = vm.heap().allocate_without_realm<PrimitiveString>(string);
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string_cache.set(move(string), new_string);
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return *new_string;
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}
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ThrowCompletionOr<NonnullGCPtr<PrimitiveString>> PrimitiveString::create(VM& vm, StringView string)
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{
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return create(vm, TRY_OR_THROW_OOM(vm, String::from_utf8(string)));
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}
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NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, DeprecatedString string)
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{
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if (string.is_empty())
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return vm.empty_string();
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if (string.length() == 1) {
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auto ch = static_cast<u8>(string.characters()[0]);
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if (is_ascii(ch))
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return vm.single_ascii_character_string(ch);
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}
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auto& string_cache = vm.deprecated_string_cache();
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auto it = string_cache.find(string);
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if (it == string_cache.end()) {
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auto new_string = vm.heap().allocate_without_realm<PrimitiveString>(string);
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string_cache.set(move(string), new_string);
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return *new_string;
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}
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return *it->value;
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}
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NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, DeprecatedFlyString const& string)
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{
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return create(vm, string.impl());
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}
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NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, PrimitiveString& lhs, PrimitiveString& rhs)
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{
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// We're here to concatenate two strings into a new rope string.
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// However, if any of them are empty, no rope is required.
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bool lhs_empty = lhs.is_empty();
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bool rhs_empty = rhs.is_empty();
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if (lhs_empty && rhs_empty)
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return vm.empty_string();
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if (lhs_empty)
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return rhs;
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if (rhs_empty)
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return lhs;
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return vm.heap().allocate_without_realm<PrimitiveString>(lhs, rhs);
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}
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ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed() const
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{
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if (!m_is_rope)
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return {};
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auto& vm = this->vm();
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// NOTE: Special case for two concatenated UTF-16 strings.
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// This is here as an optimization, although I'm unsure how valuable it is.
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if (m_lhs->has_utf16_string() && m_rhs->has_utf16_string()) {
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auto const& lhs_string = m_lhs->m_utf16_string.value();
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auto const& rhs_string = m_rhs->m_utf16_string.value();
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Utf16Data combined;
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TRY_OR_THROW_OOM(vm, combined.try_ensure_capacity(lhs_string.length_in_code_units() + rhs_string.length_in_code_units()));
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combined.extend(lhs_string.string());
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combined.extend(rhs_string.string());
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m_utf16_string = TRY(Utf16String::create(vm, move(combined)));
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m_is_rope = false;
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m_lhs = nullptr;
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m_rhs = nullptr;
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return {};
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}
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// This vector will hold all the pieces of the rope that need to be assembled
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// into the resolved string.
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Vector<PrimitiveString const*> pieces;
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// NOTE: We traverse the rope tree without using recursion, since we'd run out of
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// stack space quickly when handling a long sequence of unresolved concatenations.
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Vector<PrimitiveString const*> stack;
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TRY_OR_THROW_OOM(vm, stack.try_append(m_rhs));
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TRY_OR_THROW_OOM(vm, stack.try_append(m_lhs));
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while (!stack.is_empty()) {
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auto const* current = stack.take_last();
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if (current->m_is_rope) {
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TRY_OR_THROW_OOM(vm, stack.try_append(current->m_rhs));
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TRY_OR_THROW_OOM(vm, stack.try_append(current->m_lhs));
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continue;
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}
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TRY_OR_THROW_OOM(vm, pieces.try_append(current));
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}
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// Now that we have all the pieces, we can concatenate them using a StringBuilder.
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ThrowableStringBuilder builder(vm);
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// We keep track of the previous piece in order to handle surrogate pairs spread across two pieces.
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PrimitiveString const* previous = nullptr;
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for (auto const* current : pieces) {
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if (!previous) {
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// This is the very first piece, just append it and continue.
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TRY(builder.append(TRY(current->utf8_string())));
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previous = current;
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continue;
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}
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// Get the UTF-8 representations for both strings.
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auto current_string_as_utf8 = TRY(current->utf8_string_view());
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auto previous_string_as_utf8 = TRY(previous->utf8_string_view());
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// NOTE: Now we need to look at the end of the previous string and the start
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// of the current string, to see if they should be combined into a surrogate.
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// Surrogates encoded as UTF-8 are 3 bytes.
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if ((previous_string_as_utf8.length() < 3) || (current_string_as_utf8.length() < 3)) {
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TRY(builder.append(current_string_as_utf8));
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previous = current;
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continue;
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}
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// Might the previous string end with a UTF-8 encoded surrogate?
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if ((static_cast<u8>(previous_string_as_utf8[previous_string_as_utf8.length() - 3]) & 0xf0) != 0xe0) {
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// If not, just append the current string and continue.
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TRY(builder.append(current_string_as_utf8));
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previous = current;
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continue;
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}
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// Might the current string begin with a UTF-8 encoded surrogate?
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if ((static_cast<u8>(current_string_as_utf8[0]) & 0xf0) != 0xe0) {
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// If not, just append the current string and continue.
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TRY(builder.append(current_string_as_utf8));
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previous = current;
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continue;
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}
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auto high_surrogate = *Utf8View(previous_string_as_utf8.substring_view(previous_string_as_utf8.length() - 3)).begin();
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auto low_surrogate = *Utf8View(current_string_as_utf8).begin();
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if (!Utf16View::is_high_surrogate(high_surrogate) || !Utf16View::is_low_surrogate(low_surrogate)) {
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TRY(builder.append(current_string_as_utf8));
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previous = current;
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continue;
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}
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// Remove 3 bytes from the builder and replace them with the UTF-8 encoded code point.
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builder.trim(3);
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TRY(builder.append_code_point(Utf16View::decode_surrogate_pair(high_surrogate, low_surrogate)));
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// Append the remaining part of the current string.
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TRY(builder.append(current_string_as_utf8.substring_view(3)));
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previous = current;
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}
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m_utf8_string = TRY(builder.to_string());
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m_is_rope = false;
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m_lhs = nullptr;
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m_rhs = nullptr;
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return {};
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}
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}
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