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AK: Replace the mutable String::replace API with an immutable version

This removes the awkward String::replace API which was the only String
API which mutated the String and replaces it with a new immutable
version that returns a new String with the replacements applied. This
also fixes a couple of UAFs that were caused by the use of this API.

As an optimization an equivalent StringView::replace API was also added
to remove an unnecessary String allocations in the format of:
`String { view }.replace(...);`
This commit is contained in:
Idan Horowitz 2021-09-11 02:15:44 +03:00
parent aba4c9579f
commit 6704961c82
26 changed files with 72 additions and 118 deletions

View file

@ -352,36 +352,6 @@ bool String::equals_ignoring_case(const StringView& other) const
return StringUtils::equals_ignoring_case(view(), other);
}
int String::replace(const String& needle, const String& replacement, bool all_occurrences)
{
if (is_empty())
return 0;
Vector<size_t> positions;
if (all_occurrences) {
positions = find_all(needle);
} else {
auto pos = find(needle);
if (!pos.has_value())
return 0;
positions.append(pos.value());
}
if (!positions.size())
return 0;
StringBuilder b;
size_t lastpos = 0;
for (auto& pos : positions) {
b.append(substring_view(lastpos, pos - lastpos));
b.append(replacement);
lastpos = pos + needle.length();
}
b.append(substring_view(lastpos, length() - lastpos));
m_impl = StringImpl::create(b.build().characters());
return positions.size();
}
String String::reverse() const
{
StringBuilder reversed_string(length());

View file

@ -285,7 +285,7 @@ public:
return { characters(), length() };
}
int replace(const String& needle, const String& replacement, bool all_occurrences = false);
[[nodiscard]] String replace(const StringView& needle, const StringView& replacement, bool all_occurrences = false) const { return StringUtils::replace(*this, needle, replacement, all_occurrences); }
[[nodiscard]] size_t count(StringView const& needle) const { return StringUtils::count(*this, needle); }
[[nodiscard]] String reverse() const;

View file

@ -427,6 +427,34 @@ String to_titlecase(StringView const& str)
return builder.to_string();
}
String replace(StringView const& str, StringView const& needle, StringView const& replacement, bool all_occurrences)
{
if (str.is_empty())
return str;
Vector<size_t> positions;
if (all_occurrences) {
positions = str.find_all(needle);
if (!positions.size())
return str;
} else {
auto pos = str.find(needle);
if (!pos.has_value())
return str;
positions.append(pos.value());
}
StringBuilder replaced_string;
size_t last_position = 0;
for (auto& position : positions) {
replaced_string.append(str.substring_view(last_position, position - last_position));
replaced_string.append(replacement);
last_position = position + needle.length();
}
replaced_string.append(str.substring_view(last_position, str.length() - last_position));
return replaced_string.build();
}
// TODO: Benchmark against KMP (AK/MemMem.h) and switch over if it's faster for short strings too
size_t count(StringView const& str, StringView const& needle)
{

View file

@ -71,6 +71,7 @@ Optional<size_t> find_any_of(StringView const& haystack, StringView const& needl
String to_snakecase(const StringView&);
String to_titlecase(StringView const&);
String replace(StringView const&, StringView const& needle, StringView const& replacement, bool all_occurrences = false);
size_t count(StringView const&, StringView const& needle);
}

View file

@ -245,4 +245,9 @@ bool StringView::operator==(const String& string) const
String StringView::to_string() const { return String { *this }; }
String StringView::replace(const StringView& needle, const StringView& replacement, bool all_occurrences) const
{
return StringUtils::replace(*this, needle, replacement, all_occurrences);
}
}

View file

@ -220,6 +220,7 @@ public:
[[nodiscard]] bool is_whitespace() const { return StringUtils::is_whitespace(*this); }
[[nodiscard]] String replace(const StringView& needle, const StringView& replacement, bool all_occurrences = false) const;
[[nodiscard]] size_t count(StringView const& needle) const { return StringUtils::count(*this, needle); }
template<typename... Ts>

View file

@ -203,15 +203,12 @@ URL URLParser::parse(Badge<URL>, StringView const& raw_input, URL const* base_ur
if (start_index >= end_index)
return {};
auto processed_input = raw_input.substring_view(start_index, end_index - start_index);
String processed_input = raw_input.substring_view(start_index, end_index - start_index);
// NOTE: This replaces all tab and newline characters with nothing.
if (processed_input.contains("\t") || processed_input.contains("\n")) {
report_validation_error();
String processed_input_string(processed_input);
processed_input_string.replace("\t", "", true);
processed_input_string.replace("\n", "", true);
processed_input = processed_input_string;
processed_input = processed_input.replace("\t", "", true).replace("\n", "", true);
}
State state = State::SchemeStart;