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serenity/Userland/Libraries/LibRegex/RegexMatch.h
Timothy Flynn 9509433e25 LibRegex: Implement and use a REPEAT operation for bytecode repetition 
Currently, when we need to repeat an instruction N times, we simply add
that instruction N times in a for-loop. This doesn't scale well with
extremely large values of N, and ECMA-262 allows up to N = 2^53 - 1.

Instead, add a new REPEAT bytecode operation to defer this loop from the
parser to the runtime executor. This allows the parser to complete sans
any loops (for this instruction), and allows the executor to bail early
if the repeated bytecode fails.

Note: The templated ByteCode methods are to allow the Posix parsers to
continue using u32 because they are limited to N = 2^20.
2021-08-15 11:43:45 +01:00

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/*
* Copyright (c) 2020, Emanuel Sprung <emanuel.sprung@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include "RegexOptions.h"
#include <AK/FlyString.h>
#include <AK/HashMap.h>
#include <AK/MemMem.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>
#include <AK/StringView.h>
#include <AK/Utf16View.h>
#include <AK/Utf32View.h>
#include <AK/Utf8View.h>
#include <AK/Variant.h>
#include <AK/Vector.h>
namespace regex {
class RegexStringView {
public:
RegexStringView(char const* chars)
: m_view(StringView { chars })
{
}
RegexStringView(String const& string)
: m_view(string.view())
{
}
RegexStringView(StringView const view)
: m_view(view)
{
}
RegexStringView(Utf32View view)
: m_view(view)
{
}
RegexStringView(Utf16View view)
: m_view(view)
{
}
RegexStringView(Utf8View view)
: m_view(view)
{
}
StringView const& string_view() const
{
return m_view.get<StringView>();
}
Utf32View const& u32_view() const
{
return m_view.get<Utf32View>();
}
Utf16View const& u16_view() const
{
return m_view.get<Utf16View>();
}
Utf8View const& u8_view() const
{
return m_view.get<Utf8View>();
}
bool unicode() const { return m_unicode; }
void set_unicode(bool unicode) { m_unicode = unicode; }
bool is_empty() const
{
return m_view.visit([](auto& view) { return view.is_empty(); });
}
bool is_null() const
{
return m_view.visit([](auto& view) { return view.is_null(); });
}
size_t length() const
{
if (unicode()) {
return m_view.visit(
[](Utf16View const& view) { return view.length_in_code_points(); },
[](auto const& view) { return view.length(); });
}
return length_in_code_units();
}
size_t length_in_code_units() const
{
return m_view.visit(
[](Utf16View const& view) { return view.length_in_code_units(); },
[](Utf8View const& view) { return view.byte_length(); },
[](auto const& view) { return view.length(); });
}
size_t length_of_code_point(u32 code_point) const
{
return m_view.visit(
[](Utf32View const&) { return 1; },
[&](Utf16View const&) {
if (code_point < 0x10000)
return 1;
return 2;
},
[&](auto const&) {
if (code_point <= 0x7f)
return 1;
else if (code_point <= 0x07ff)
return 2;
else if (code_point <= 0xffff)
return 3;
return 4;
});
}
RegexStringView typed_null_view()
{
auto view = m_view.visit(
[&]<typename T>(T const&) {
return RegexStringView { T {} };
});
view.set_unicode(unicode());
return view;
}
RegexStringView construct_as_same(Span<u32> data, Optional<String>& optional_string_storage, Vector<u16>& optional_utf16_storage) const
{
auto view = m_view.visit(
[&]<typename T>(T const&) {
StringBuilder builder;
for (auto ch : data)
builder.append(ch); // Note: The type conversion is intentional.
optional_string_storage = builder.build();
return RegexStringView { T { *optional_string_storage } };
},
[&](Utf32View) {
return RegexStringView { Utf32View { data.data(), data.size() } };
},
[&](Utf16View) {
optional_utf16_storage = AK::utf32_to_utf16(Utf32View { data.data(), data.size() });
return RegexStringView { Utf16View { optional_utf16_storage } };
});
view.set_unicode(unicode());
return view;
}
Vector<RegexStringView> lines() const
{
return m_view.visit(
[](StringView view) {
auto views = view.lines(false);
Vector<RegexStringView> new_views;
for (auto& view : views)
new_views.empend(view);
return new_views;
},
[](Utf32View view) {
Vector<RegexStringView> views;
u32 newline = '\n';
while (!view.is_empty()) {
auto position = AK::memmem_optional(view.code_points(), view.length() * sizeof(u32), &newline, sizeof(u32));
if (!position.has_value())
break;
auto offset = position.value() / sizeof(u32);
views.empend(view.substring_view(0, offset));
view = view.substring_view(offset + 1, view.length() - offset - 1);
}
if (!view.is_empty())
views.empend(view);
return views;
},
[](Utf16View view) {
Vector<RegexStringView> views;
u16 newline = '\n';
while (!view.is_empty()) {
auto position = AK::memmem_optional(view.data(), view.length_in_code_units() * sizeof(u16), &newline, sizeof(u16));
if (!position.has_value())
break;
auto offset = position.value() / sizeof(u16);
views.empend(view.substring_view(0, offset));
view = view.substring_view(offset + 1, view.length_in_code_units() - offset - 1);
}
if (!view.is_empty())
views.empend(view);
return views;
},
[](Utf8View& view) {
Vector<RegexStringView> views;
auto it = view.begin();
auto previous_newline_position_it = it;
for (;;) {
if (*it == '\n') {
auto previous_offset = view.byte_offset_of(previous_newline_position_it);
auto new_offset = view.byte_offset_of(it);
auto slice = view.substring_view(previous_offset, new_offset - previous_offset);
views.empend(slice);
++it;
previous_newline_position_it = it;
}
if (it.done())
break;
++it;
}
if (it != previous_newline_position_it) {
auto previous_offset = view.byte_offset_of(previous_newline_position_it);
auto new_offset = view.byte_offset_of(it);
auto slice = view.substring_view(previous_offset, new_offset - previous_offset);
views.empend(slice);
}
return views;
});
}
RegexStringView substring_view(size_t offset, size_t length) const
{
if (unicode()) {
auto view = m_view.visit(
[&](auto view) { return RegexStringView { view.substring_view(offset, length) }; },
[&](Utf16View const& view) { return RegexStringView { view.unicode_substring_view(offset, length) }; },
[&](Utf8View const& view) { return RegexStringView { view.unicode_substring_view(offset, length) }; });
view.set_unicode(unicode());
return view;
}
auto view = m_view.visit([&](auto view) { return RegexStringView { view.substring_view(offset, length) }; });
view.set_unicode(unicode());
return view;
}
String to_string() const
{
return m_view.visit(
[](StringView view) { return view.to_string(); },
[](Utf16View view) { return view.to_utf8(Utf16View::AllowInvalidCodeUnits::Yes); },
[](auto& view) {
StringBuilder builder;
for (auto it = view.begin(); it != view.end(); ++it)
builder.append_code_point(*it);
return builder.to_string();
});
}
// Note: index must always be the code unit offset to return.
u32 operator[](size_t index) const
{
return m_view.visit(
[&](StringView view) -> u32 {
auto ch = view[index];
if (ch < 0)
return 256u + ch;
return ch;
},
[&](Utf32View const& view) -> u32 { return view[index]; },
[&](Utf16View const& view) -> u32 { return view.code_point_at(index); },
[&](Utf8View const& view) -> u32 {
auto it = view.iterator_at_byte_offset(index);
VERIFY(it != view.end());
return *it;
});
}
bool operator==(char const* cstring) const
{
return m_view.visit(
[&](Utf32View) { return to_string() == cstring; },
[&](Utf16View) { return to_string() == cstring; },
[&](Utf8View const& view) { return view.as_string() == cstring; },
[&](StringView view) { return view == cstring; });
}
bool operator!=(char const* cstring) const
{
return !(*this == cstring);
}
bool operator==(String const& string) const
{
return m_view.visit(
[&](Utf32View) { return to_string() == string; },
[&](Utf16View) { return to_string() == string; },
[&](Utf8View const& view) { return view.as_string() == string; },
[&](StringView view) { return view == string; });
}
bool operator==(StringView const& string) const
{
return m_view.visit(
[&](Utf32View) { return to_string() == string; },
[&](Utf16View) { return to_string() == string; },
[&](Utf8View const& view) { return view.as_string() == string; },
[&](StringView view) { return view == string; });
}
bool operator!=(StringView const& other) const
{
return !(*this == other);
}
bool operator==(Utf32View const& other) const
{
return m_view.visit(
[&](Utf32View view) {
return view.length() == other.length() && __builtin_memcmp(view.code_points(), other.code_points(), view.length() * sizeof(u32)) == 0;
},
[&](Utf16View) { return to_string() == RegexStringView { other }.to_string(); },
[&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_string(); },
[&](StringView view) { return view == RegexStringView { other }.to_string(); });
}
bool operator!=(Utf32View const& other) const
{
return !(*this == other);
}
bool operator==(Utf16View const& other) const
{
return m_view.visit(
[&](Utf32View) { return to_string() == RegexStringView { other }.to_string(); },
[&](Utf16View const& view) { return view == other; },
[&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_string(); },
[&](StringView view) { return view == RegexStringView { other }.to_string(); });
}
bool operator!=(Utf16View const& other) const
{
return !(*this == other);
}
bool operator==(Utf8View const& other) const
{
return m_view.visit(
[&](Utf32View) { return to_string() == other.as_string(); },
[&](Utf16View) { return to_string() == other.as_string(); },
[&](Utf8View const& view) { return view.as_string() == other.as_string(); },
[&](StringView view) { return other.as_string() == view; });
}
bool operator!=(Utf8View const& other) const
{
return !(*this == other);
}
bool equals(RegexStringView const& other) const
{
return other.m_view.visit([&](auto const& view) { return operator==(view); });
}
bool equals_ignoring_case(RegexStringView const& other) const
{
// FIXME: Implement equals_ignoring_case() for unicode.
return m_view.visit(
[&](StringView view) {
return other.m_view.visit(
[&](StringView other_view) { return view.equals_ignoring_case(other_view); },
[](auto&) -> bool { TODO(); });
},
[&](Utf16View view) {
return other.m_view.visit(
[&](Utf16View other_view) { return view.equals_ignoring_case(other_view); },
[](auto&) -> bool { TODO(); });
},
[](auto&) -> bool { TODO(); });
}
bool starts_with(StringView const& str) const
{
return m_view.visit(
[&](Utf32View) -> bool {
TODO();
},
[&](Utf16View) -> bool {
TODO();
},
[&](Utf8View const& view) { return view.as_string().starts_with(str); },
[&](StringView view) { return view.starts_with(str); });
}
bool starts_with(Utf32View const& str) const
{
return m_view.visit(
[&](Utf32View view) -> bool {
if (str.length() > view.length())
return false;
if (str.length() == view.length())
return operator==(str);
for (size_t i = 0; i < str.length(); ++i) {
if (str.at(i) != view.at(i))
return false;
}
return true;
},
[&](Utf16View) -> bool { TODO(); },
[&](Utf8View const& view) {
auto it = view.begin();
for (auto code_point : str) {
if (it.done())
return false;
if (code_point != *it)
return false;
++it;
}
return true;
},
[&](StringView) -> bool { TODO(); });
}
private:
Variant<StringView, Utf8View, Utf16View, Utf32View> m_view;
bool m_unicode { false };
};
class Match final {
private:
Optional<FlyString> string;
public:
Match() = default;
~Match() = default;
Match(RegexStringView const view_, size_t const line_, size_t const column_, size_t const global_offset_)
: view(view_)
, line(line_)
, column(column_)
, global_offset(global_offset_)
, left_column(column_)
{
}
Match(String const string_, size_t const line_, size_t const column_, size_t const global_offset_)
: string(move(string_))
, view(string.value().view())
, line(line_)
, column(column_)
, global_offset(global_offset_)
{
}
Match(RegexStringView const view_, StringView capture_group_name_, size_t const line_, size_t const column_, size_t const global_offset_)
: view(view_)
, capture_group_name(capture_group_name_)
, line(line_)
, column(column_)
, global_offset(global_offset_)
, left_column(column_)
{
}
void reset()
{
view = view.typed_null_view();
capture_group_name.clear();
line = 0;
column = 0;
global_offset = 0;
left_column = 0;
}
RegexStringView view { nullptr };
Optional<StringView> capture_group_name {};
size_t line { 0 };
size_t column { 0 };
size_t global_offset { 0 };
// ugly, as not usable by user, but needed to prevent to create extra vectors that are
// able to store the column when the left paren has been found
size_t left_column { 0 };
};
struct MatchInput {
RegexStringView view { nullptr };
AllOptions regex_options {};
size_t start_offset { 0 }; // For Stateful matches, saved and restored from Regex::start_offset.
size_t match_index { 0 };
size_t line { 0 };
size_t column { 0 };
size_t global_offset { 0 }; // For multiline matching, knowing the offset from start could be important
mutable size_t fail_counter { 0 };
mutable Vector<size_t> saved_positions;
mutable Vector<size_t> saved_code_unit_positions;
};
struct MatchState {
size_t string_position_before_match { 0 };
size_t string_position { 0 };
size_t string_position_in_code_units { 0 };
size_t instruction_position { 0 };
size_t fork_at_position { 0 };
Vector<Match> matches;
Vector<Vector<Match>> capture_group_matches;
Vector<u64> repetition_marks;
};
}
using regex::RegexStringView;
template<>
struct AK::Formatter<regex::RegexStringView> : Formatter<StringView> {
void format(FormatBuilder& builder, regex::RegexStringView const& value)
{
auto string = value.to_string();
return Formatter<StringView>::format(builder, string);
}
};
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