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LibJS: Make PrimitiveString::resolve_rope_if_needed() infallible

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Work towards #20449.
This commit is contained in:
Andreas Kling 2023-08-08 18:34:19 +02:00
parent 1a27c525d5
commit 9708b86d65
2 changed files with 25 additions and 26 deletions
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49
Userland/Libraries/LibJS/Runtime/PrimitiveString.cpp
View file

@ -77,7 +77,7 @@ bool PrimitiveString::is_empty() const
ThrowCompletionOr<String> PrimitiveString::utf8_string() const
{
auto& vm = this->vm();
TRY(resolve_rope_if_needed(EncodingPreference::UTF8));
resolve_rope_if_needed(EncodingPreference::UTF8);
if (!has_utf8_string()) {
if (has_deprecated_string())
@ -99,7 +99,7 @@ ThrowCompletionOr<StringView> PrimitiveString::utf8_string_view() const
ThrowCompletionOr<DeprecatedString> PrimitiveString::deprecated_string() const
{
TRY(resolve_rope_if_needed(EncodingPreference::UTF8));
resolve_rope_if_needed(EncodingPreference::UTF8);
if (!has_deprecated_string()) {
if (has_utf8_string())
@ -115,7 +115,7 @@ ThrowCompletionOr<DeprecatedString> PrimitiveString::deprecated_string() const
ThrowCompletionOr<Utf16String> PrimitiveString::utf16_string() const
{
TRY(resolve_rope_if_needed(EncodingPreference::UTF16));
resolve_rope_if_needed(EncodingPreference::UTF16);
if (!has_utf16_string()) {
if (has_utf8_string()) {
@ -245,10 +245,10 @@ NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, PrimitiveString& l
return vm.heap().allocate_without_realm<PrimitiveString>(lhs, rhs);
}
ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreference preference) const
void PrimitiveString::resolve_rope_if_needed(EncodingPreference preference) const
{
if (!m_is_rope)
return {};
return;
auto& vm = this->vm();
@ -259,16 +259,16 @@ ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreferen
// NOTE: We traverse the rope tree without using recursion, since we'd run out of
// stack space quickly when handling a long sequence of unresolved concatenations.
Vector<PrimitiveString const*> stack;
TRY_OR_THROW_OOM(vm, stack.try_append(m_rhs));
TRY_OR_THROW_OOM(vm, stack.try_append(m_lhs));
stack.append(m_rhs);
stack.append(m_lhs);
while (!stack.is_empty()) {
auto const* current = stack.take_last();
if (current->m_is_rope) {
TRY_OR_THROW_OOM(vm, stack.try_append(current->m_rhs));
TRY_OR_THROW_OOM(vm, stack.try_append(current->m_lhs));
stack.append(current->m_rhs);
stack.append(current->m_lhs);
continue;
}
TRY_OR_THROW_OOM(vm, pieces.try_append(current));
pieces.append(current);
}
if (preference == EncodingPreference::UTF16) {
@ -277,38 +277,38 @@ ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreferen
Utf16Data code_units;
for (auto const* current : pieces)
code_units.extend(TRY(current->utf16_string()).string());
code_units.extend(MUST(current->utf16_string()).string());
m_utf16_string = TRY(Utf16String::create(vm, move(code_units)));
m_utf16_string = MUST(Utf16String::create(vm, move(code_units)));
m_is_rope = false;
m_lhs = nullptr;
m_rhs = nullptr;
return {};
return;
}
// Now that we have all the pieces, we can concatenate them using a StringBuilder.
ThrowableStringBuilder builder(vm);
StringBuilder builder;
// We keep track of the previous piece in order to handle surrogate pairs spread across two pieces.
PrimitiveString const* previous = nullptr;
for (auto const* current : pieces) {
if (!previous) {
// This is the very first piece, just append it and continue.
TRY(builder.append(TRY(current->utf8_string())));
builder.append(MUST(current->utf8_string()));
previous = current;
continue;
}
// Get the UTF-8 representations for both strings.
auto current_string_as_utf8 = TRY(current->utf8_string_view());
auto previous_string_as_utf8 = TRY(previous->utf8_string_view());
auto current_string_as_utf8 = MUST(current->utf8_string_view());
auto previous_string_as_utf8 = MUST(previous->utf8_string_view());
// NOTE: Now we need to look at the end of the previous string and the start
// of the current string, to see if they should be combined into a surrogate.
// Surrogates encoded as UTF-8 are 3 bytes.
if ((previous_string_as_utf8.length() < 3) || (current_string_as_utf8.length() < 3)) {
TRY(builder.append(current_string_as_utf8));
builder.append(current_string_as_utf8);
previous = current;
continue;
}
@ -316,7 +316,7 @@ ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreferen
// Might the previous string end with a UTF-8 encoded surrogate?
if ((static_cast<u8>(previous_string_as_utf8[previous_string_as_utf8.length() - 3]) & 0xf0) != 0xe0) {
// If not, just append the current string and continue.
TRY(builder.append(current_string_as_utf8));
builder.append(current_string_as_utf8);
previous = current;
continue;
}
@ -324,7 +324,7 @@ ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreferen
// Might the current string begin with a UTF-8 encoded surrogate?
if ((static_cast<u8>(current_string_as_utf8[0]) & 0xf0) != 0xe0) {
// If not, just append the current string and continue.
TRY(builder.append(current_string_as_utf8));
builder.append(current_string_as_utf8);
previous = current;
continue;
}
@ -333,25 +333,24 @@ ThrowCompletionOr<void> PrimitiveString::resolve_rope_if_needed(EncodingPreferen
auto low_surrogate = *Utf8View(current_string_as_utf8).begin();
if (!Utf16View::is_high_surrogate(high_surrogate) || !Utf16View::is_low_surrogate(low_surrogate)) {
TRY(builder.append(current_string_as_utf8));
builder.append(current_string_as_utf8);
previous = current;
continue;
}
// Remove 3 bytes from the builder and replace them with the UTF-8 encoded code point.
builder.trim(3);
TRY(builder.append_code_point(Utf16View::decode_surrogate_pair(high_surrogate, low_surrogate)));
builder.append_code_point(Utf16View::decode_surrogate_pair(high_surrogate, low_surrogate));
// Append the remaining part of the current string.
TRY(builder.append(current_string_as_utf8.substring_view(3)));
builder.append(current_string_as_utf8.substring_view(3));
previous = current;
}
m_utf8_string = TRY(builder.to_string());
m_utf8_string = MUST(builder.to_string());
m_is_rope = false;
m_lhs = nullptr;
m_rhs = nullptr;
return {};
}
}

2
Userland/Libraries/LibJS/Runtime/PrimitiveString.h
View file

@ -63,7 +63,7 @@ private:
UTF8,
UTF16,
};
ThrowCompletionOr<void> resolve_rope_if_needed(EncodingPreference) const;
void resolve_rope_if_needed(EncodingPreference) const;
mutable bool m_is_rope { false };