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// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "irregexp/imported/regexp-compiler.h"
#include "irregexp/imported/regexp.h"
#ifdef V8_INTL_SUPPORT
#include "irregexp/imported/special-case.h"
#include "unicode/locid.h"
#include "unicode/uniset.h"
#include "unicode/utypes.h"
#endif // V8_INTL_SUPPORT
namespace v8 {
namespace internal {
using namespace regexp_compiler_constants; // NOLINT(build/namespaces)
constexpr base::uc32 kMaxCodePoint = 0x10ffff;
constexpr int kMaxUtf16CodeUnit = 0xffff;
constexpr uint32_t kMaxUtf16CodeUnitU = 0xffff;
constexpr int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
// -------------------------------------------------------------------
// Tree to graph conversion
RegExpNode* RegExpAtom::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
ZoneList<TextElement>* elms =
compiler->zone()->New<ZoneList<TextElement>>(1, compiler->zone());
elms->Add(TextElement::Atom(this), compiler->zone());
return compiler->zone()->New<TextNode>(elms, compiler->read_backward(),
on_success);
}
RegExpNode* RegExpText::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
return compiler->zone()->New<TextNode>(elements(), compiler->read_backward(),
on_success);
}
namespace {
bool CompareInverseRanges(ZoneList<CharacterRange>* ranges,
const int* special_class, int length) {
length--; // Remove final marker.
DCHECK_EQ(kRangeEndMarker, special_class[length]);
DCHECK_NE(0, ranges->length());
DCHECK_NE(0, length);
DCHECK_NE(0, special_class[0]);
if (ranges->length() != (length >> 1) + 1) return false;
CharacterRange range = ranges->at(0);
if (range.from() != 0) return false;
for (int i = 0; i < length; i += 2) {
if (static_cast<base::uc32>(special_class[i]) != (range.to() + 1)) {
return false;
}
range = ranges->at((i >> 1) + 1);
if (static_cast<base::uc32>(special_class[i + 1]) != range.from()) {
return false;
}
}
return range.to() == kMaxCodePoint;
}
bool CompareRanges(ZoneList<CharacterRange>* ranges, const int* special_class,
int length) {
length--; // Remove final marker.
DCHECK_EQ(kRangeEndMarker, special_class[length]);
if (ranges->length() * 2 != length) return false;
for (int i = 0; i < length; i += 2) {
CharacterRange range = ranges->at(i >> 1);
if (range.from() != static_cast<base::uc32>(special_class[i]) ||
range.to() != static_cast<base::uc32>(special_class[i + 1] - 1)) {
return false;
}
}
return true;
}
} // namespace
bool RegExpClassRanges::is_standard(Zone* zone) {
// TODO(lrn): Remove need for this function, by not throwing away information
// along the way.
if (is_negated()) {
return false;
}
if (set_.is_standard()) {
return true;
}
if (CompareRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kWhitespace);
return true;
}
if (CompareInverseRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kNotWhitespace);
return true;
}
if (CompareInverseRanges(set_.ranges(zone), kLineTerminatorRanges,
kLineTerminatorRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kNotLineTerminator);
return true;
}
if (CompareRanges(set_.ranges(zone), kLineTerminatorRanges,
kLineTerminatorRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kLineTerminator);
return true;
}
if (CompareRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kWord);
return true;
}
if (CompareInverseRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
set_.set_standard_set_type(StandardCharacterSet::kNotWord);
return true;
}
return false;
}
UnicodeRangeSplitter::UnicodeRangeSplitter(ZoneList<CharacterRange>* base) {
// The unicode range splitter categorizes given character ranges into:
// - Code points from the BMP representable by one code unit.
// - Code points outside the BMP that need to be split into
// surrogate pairs.
// - Lone lead surrogates.
// - Lone trail surrogates.
// Lone surrogates are valid code points, even though no actual characters.
// They require special matching to make sure we do not split surrogate pairs.
for (int i = 0; i < base->length(); i++) AddRange(base->at(i));
}
void UnicodeRangeSplitter::AddRange(CharacterRange range) {
static constexpr base::uc32 kBmp1Start = 0;
static constexpr base::uc32 kBmp1End = kLeadSurrogateStart - 1;
static constexpr base::uc32 kBmp2Start = kTrailSurrogateEnd + 1;
static constexpr base::uc32 kBmp2End = kNonBmpStart - 1;
// Ends are all inclusive.
static_assert(kBmp1Start == 0);
static_assert(kBmp1Start < kBmp1End);
static_assert(kBmp1End + 1 == kLeadSurrogateStart);
static_assert(kLeadSurrogateStart < kLeadSurrogateEnd);
static_assert(kLeadSurrogateEnd + 1 == kTrailSurrogateStart);
static_assert(kTrailSurrogateStart < kTrailSurrogateEnd);
static_assert(kTrailSurrogateEnd + 1 == kBmp2Start);
static_assert(kBmp2Start < kBmp2End);
static_assert(kBmp2End + 1 == kNonBmpStart);
static_assert(kNonBmpStart < kNonBmpEnd);
static constexpr base::uc32 kStarts[] = {
kBmp1Start, kLeadSurrogateStart, kTrailSurrogateStart,
kBmp2Start, kNonBmpStart,
};
static constexpr base::uc32 kEnds[] = {
kBmp1End, kLeadSurrogateEnd, kTrailSurrogateEnd, kBmp2End, kNonBmpEnd,
};
CharacterRangeVector* const kTargets[] = {
&bmp_, &lead_surrogates_, &trail_surrogates_, &bmp_, &non_bmp_,
};
static constexpr int kCount = arraysize(kStarts);
static_assert(kCount == arraysize(kEnds));
static_assert(kCount == arraysize(kTargets));
for (int i = 0; i < kCount; i++) {
if (kStarts[i] > range.to()) break;
const base::uc32 from = std::max(kStarts[i], range.from());
const base::uc32 to = std::min(kEnds[i], range.to());
if (from > to) continue;
kTargets[i]->emplace_back(CharacterRange::Range(from, to));
}
}
namespace {
// Translates between new and old V8-isms (SmallVector, ZoneList).
ZoneList<CharacterRange>* ToCanonicalZoneList(
const UnicodeRangeSplitter::CharacterRangeVector* v, Zone* zone) {
if (v->empty()) return nullptr;
ZoneList<CharacterRange>* result =
zone->New<ZoneList<CharacterRange>>(static_cast<int>(v->size()), zone);
for (size_t i = 0; i < v->size(); i++) {
result->Add(v->at(i), zone);
}
CharacterRange::Canonicalize(result);
return result;
}
void AddBmpCharacters(RegExpCompiler* compiler, ChoiceNode* result,
RegExpNode* on_success, UnicodeRangeSplitter* splitter) {
ZoneList<CharacterRange>* bmp =
ToCanonicalZoneList(splitter->bmp(), compiler->zone());
if (bmp == nullptr) return;
result->AddAlternative(GuardedAlternative(TextNode::CreateForCharacterRanges(
compiler->zone(), bmp, compiler->read_backward(), on_success)));
}
using UC16Range = uint32_t; // {from, to} packed into one uint32_t.
constexpr UC16Range ToUC16Range(base::uc16 from, base::uc16 to) {
return (static_cast<uint32_t>(from) << 16) | to;
}
constexpr base::uc16 ExtractFrom(UC16Range r) {
return static_cast<base::uc16>(r >> 16);
}
constexpr base::uc16 ExtractTo(UC16Range r) {
return static_cast<base::uc16>(r);
}
void AddNonBmpSurrogatePairs(RegExpCompiler* compiler, ChoiceNode* result,
RegExpNode* on_success,
UnicodeRangeSplitter* splitter) {
DCHECK(!compiler->one_byte());
Zone* const zone = compiler->zone();
ZoneList<CharacterRange>* non_bmp =
ToCanonicalZoneList(splitter->non_bmp(), zone);
if (non_bmp == nullptr) return;
// Translate each 32-bit code point range into the corresponding 16-bit code
// unit representation consisting of the lead- and trail surrogate.
//
// The generated alternatives are grouped by the leading surrogate to avoid
// emitting excessive code. For example, for
//
// { \ud800[\udc00-\udc01]
// , \ud800[\udc05-\udc06]
// }
//
// there's no need to emit matching code for the leading surrogate \ud800
// twice. We also create a dedicated grouping for full trailing ranges, i.e.
// [dc00-dfff].
ZoneUnorderedMap<UC16Range, ZoneList<CharacterRange>*> grouped_by_leading(
zone);
ZoneList<CharacterRange>* leading_with_full_trailing_range =
zone->New<ZoneList<CharacterRange>>(1, zone);
const auto AddRange = [&](base::uc16 from_l, base::uc16 to_l,
base::uc16 from_t, base::uc16 to_t) {
const UC16Range leading_range = ToUC16Range(from_l, to_l);
if (grouped_by_leading.count(leading_range) == 0) {
if (from_t == kTrailSurrogateStart && to_t == kTrailSurrogateEnd) {
leading_with_full_trailing_range->Add(
CharacterRange::Range(from_l, to_l), zone);
return;
}
grouped_by_leading[leading_range] =
zone->New<ZoneList<CharacterRange>>(2, zone);
}
grouped_by_leading[leading_range]->Add(CharacterRange::Range(from_t, to_t),
zone);
};
// First, create the grouped ranges.
CharacterRange::Canonicalize(non_bmp);
for (int i = 0; i < non_bmp->length(); i++) {
// Match surrogate pair.
// E.g. [\u10005-\u11005] becomes
// \ud800[\udc05-\udfff]|
// [\ud801-\ud803][\udc00-\udfff]|
// \ud804[\udc00-\udc05]
base::uc32 from = non_bmp->at(i).from();
base::uc32 to = non_bmp->at(i).to();
base::uc16 from_l = unibrow::Utf16::LeadSurrogate(from);
base::uc16 from_t = unibrow::Utf16::TrailSurrogate(from);
base::uc16 to_l = unibrow::Utf16::LeadSurrogate(to);
base::uc16 to_t = unibrow::Utf16::TrailSurrogate(to);
if (from_l == to_l) {
// The lead surrogate is the same.
AddRange(from_l, to_l, from_t, to_t);
continue;
}
if (from_t != kTrailSurrogateStart) {
// Add [from_l][from_t-\udfff].
AddRange(from_l, from_l, from_t, kTrailSurrogateEnd);
from_l++;
}
if (to_t != kTrailSurrogateEnd) {
// Add [to_l][\udc00-to_t].
AddRange(to_l, to_l, kTrailSurrogateStart, to_t);
to_l--;
}
if (from_l <= to_l) {
// Add [from_l-to_l][\udc00-\udfff].
AddRange(from_l, to_l, kTrailSurrogateStart, kTrailSurrogateEnd);
}
}
// Create the actual TextNode now that ranges are fully grouped.
if (!leading_with_full_trailing_range->is_empty()) {
CharacterRange::Canonicalize(leading_with_full_trailing_range);
result->AddAlternative(GuardedAlternative(TextNode::CreateForSurrogatePair(
zone, leading_with_full_trailing_range,
CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd),
compiler->read_backward(), on_success)));
}
for (const auto& it : grouped_by_leading) {
CharacterRange leading_range =
CharacterRange::Range(ExtractFrom(it.first), ExtractTo(it.first));
ZoneList<CharacterRange>* trailing_ranges = it.second;
CharacterRange::Canonicalize(trailing_ranges);
result->AddAlternative(GuardedAlternative(TextNode::CreateForSurrogatePair(
zone, leading_range, trailing_ranges, compiler->read_backward(),
on_success)));
}
}
RegExpNode* NegativeLookaroundAgainstReadDirectionAndMatch(
RegExpCompiler* compiler, ZoneList<CharacterRange>* lookbehind,
ZoneList<CharacterRange>* match, RegExpNode* on_success,
bool read_backward) {
Zone* zone = compiler->zone();
RegExpNode* match_node = TextNode::CreateForCharacterRanges(
zone, match, read_backward, on_success);
int stack_register = compiler->UnicodeLookaroundStackRegister();
int position_register = compiler->UnicodeLookaroundPositionRegister();
RegExpLookaround::Builder lookaround(false, match_node, stack_register,
position_register);
RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
zone, lookbehind, !read_backward, lookaround.on_match_success());
return lookaround.ForMatch(negative_match);
}
RegExpNode* MatchAndNegativeLookaroundInReadDirection(
RegExpCompiler* compiler, ZoneList<CharacterRange>* match,
ZoneList<CharacterRange>* lookahead, RegExpNode* on_success,
bool read_backward) {
Zone* zone = compiler->zone();
int stack_register = compiler->UnicodeLookaroundStackRegister();
int position_register = compiler->UnicodeLookaroundPositionRegister();
RegExpLookaround::Builder lookaround(false, on_success, stack_register,
position_register);
RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
zone, lookahead, read_backward, lookaround.on_match_success());
return TextNode::CreateForCharacterRanges(
zone, match, read_backward, lookaround.ForMatch(negative_match));
}
void AddLoneLeadSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
RegExpNode* on_success,
UnicodeRangeSplitter* splitter) {
ZoneList<CharacterRange>* lead_surrogates =
ToCanonicalZoneList(splitter->lead_surrogates(), compiler->zone());
if (lead_surrogates == nullptr) return;
Zone* zone = compiler->zone();
// E.g. \ud801 becomes \ud801(?![\udc00-\udfff]).
ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
zone, CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
RegExpNode* match;
if (compiler->read_backward()) {
// Reading backward. Assert that reading forward, there is no trail
// surrogate, and then backward match the lead surrogate.
match = NegativeLookaroundAgainstReadDirectionAndMatch(
compiler, trail_surrogates, lead_surrogates, on_success, true);
} else {
// Reading forward. Forward match the lead surrogate and assert that
// no trail surrogate follows.
match = MatchAndNegativeLookaroundInReadDirection(
compiler, lead_surrogates, trail_surrogates, on_success, false);
}
result->AddAlternative(GuardedAlternative(match));
}
void AddLoneTrailSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
RegExpNode* on_success,
UnicodeRangeSplitter* splitter) {
ZoneList<CharacterRange>* trail_surrogates =
ToCanonicalZoneList(splitter->trail_surrogates(), compiler->zone());
if (trail_surrogates == nullptr) return;
Zone* zone = compiler->zone();
// E.g. \udc01 becomes (?<![\ud800-\udbff])\udc01
ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
zone, CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
RegExpNode* match;
if (compiler->read_backward()) {
// Reading backward. Backward match the trail surrogate and assert that no
// lead surrogate precedes it.
match = MatchAndNegativeLookaroundInReadDirection(
compiler, trail_surrogates, lead_surrogates, on_success, true);
} else {
// Reading forward. Assert that reading backward, there is no lead
// surrogate, and then forward match the trail surrogate.
match = NegativeLookaroundAgainstReadDirectionAndMatch(
compiler, lead_surrogates, trail_surrogates, on_success, false);
}
result->AddAlternative(GuardedAlternative(match));
}
RegExpNode* UnanchoredAdvance(RegExpCompiler* compiler,
RegExpNode* on_success) {
// This implements ES2015 21.2.5.2.3, AdvanceStringIndex.
DCHECK(!compiler->read_backward());
Zone* zone = compiler->zone();
// Advance any character. If the character happens to be a lead surrogate and
// we advanced into the middle of a surrogate pair, it will work out, as
// nothing will match from there. We will have to advance again, consuming
// the associated trail surrogate.
ZoneList<CharacterRange>* range =
CharacterRange::List(zone, CharacterRange::Range(0, kMaxUtf16CodeUnit));
return TextNode::CreateForCharacterRanges(zone, range, false, on_success);
}
} // namespace
// static
void CharacterRange::AddUnicodeCaseEquivalents(ZoneList<CharacterRange>* ranges,
Zone* zone) {
#ifdef V8_INTL_SUPPORT
DCHECK(IsCanonical(ranges));
// Micro-optimization to avoid passing large ranges to UnicodeSet::closeOver.
// TODO(jgruber): This only covers the special case of the {0,0x10FFFF} range,
// which we use frequently internally. But large ranges can also easily be
// created by the user. We might want to have a more general caching mechanism
// for such ranges.
if (ranges->length() == 1 && ranges->at(0).IsEverything(kNonBmpEnd)) return;
// Use ICU to compute the case fold closure over the ranges.
icu::UnicodeSet set;
for (int i = 0; i < ranges->length(); i++) {
set.add(ranges->at(i).from(), ranges->at(i).to());
}
// Clear the ranges list without freeing the backing store.
ranges->Rewind(0);
set.closeOver(USET_SIMPLE_CASE_INSENSITIVE);
for (int i = 0; i < set.getRangeCount(); i++) {
ranges->Add(Range(set.getRangeStart(i), set.getRangeEnd(i)), zone);
}
// No errors and everything we collected have been ranges.
Canonicalize(ranges);
#endif // V8_INTL_SUPPORT
}
RegExpNode* RegExpClassRanges::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
set_.Canonicalize();
Zone* const zone = compiler->zone();
ZoneList<CharacterRange>* ranges = this->ranges(zone);
const bool needs_case_folding =
NeedsUnicodeCaseEquivalents(compiler->flags()) && !is_case_folded();
if (needs_case_folding) {
CharacterRange::AddUnicodeCaseEquivalents(ranges, zone);
}
if (!IsEitherUnicode(compiler->flags()) || compiler->one_byte() ||
contains_split_surrogate()) {
return zone->New<TextNode>(this, compiler->read_backward(), on_success);
}
if (is_negated()) {
// With /v, character classes are never negated.
// Atom :: CharacterClass
// 4. Assert: cc.[[Invert]] is false.
// Instead the complement is created when evaluating the class set.
// The only exception is the "nothing range" (negated everything), which is
// internally created for an empty set.
DCHECK_IMPLIES(
IsUnicodeSets(compiler->flags()),
ranges->length() == 1 && ranges->first().IsEverything(kMaxCodePoint));
ZoneList<CharacterRange>* negated =
zone->New<ZoneList<CharacterRange>>(2, zone);
CharacterRange::Negate(ranges, negated, zone);
ranges = negated;
}
if (ranges->length() == 0) {
// The empty character class is used as a 'fail' node.
RegExpClassRanges* fail = zone->New<RegExpClassRanges>(zone, ranges);
return zone->New<TextNode>(fail, compiler->read_backward(), on_success);
}
if (set_.is_standard() &&
standard_type() == StandardCharacterSet::kEverything) {
return UnanchoredAdvance(compiler, on_success);
}
// Split ranges in order to handle surrogates correctly:
// - Surrogate pairs: translate the 32-bit code point into two uc16 code
// units (irregexp operates only on code units).
// - Lone surrogates: these require lookarounds to ensure we don't match in
// the middle of a surrogate pair.
ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
UnicodeRangeSplitter splitter(ranges);
AddBmpCharacters(compiler, result, on_success, &splitter);
AddNonBmpSurrogatePairs(compiler, result, on_success, &splitter);
AddLoneLeadSurrogates(compiler, result, on_success, &splitter);
AddLoneTrailSurrogates(compiler, result, on_success, &splitter);
static constexpr int kMaxRangesToInline = 32; // Arbitrary.
if (ranges->length() > kMaxRangesToInline) result->SetDoNotInline();
return result;
}
RegExpNode* RegExpClassSetOperand::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
Zone* zone = compiler->zone();
const int size = (has_strings() ? static_cast<int>(strings()->size()) : 0) +
(ranges()->is_empty() ? 0 : 1);
if (size == 0) {
// If neither ranges nor strings are present, the operand is equal to an
// empty range (matching nothing).
ZoneList<CharacterRange>* empty =
zone->template New<ZoneList<CharacterRange>>(0, zone);
return zone->template New<RegExpClassRanges>(zone, empty)
->ToNode(compiler, on_success);
}
ZoneList<RegExpTree*>* alternatives =
zone->template New<ZoneList<RegExpTree*>>(size, zone);
// Strings are sorted by length first (larger strings before shorter ones).
// See the comment on CharacterClassStrings.
// Empty strings (if present) are added after character ranges.
RegExpTree* empty_string = nullptr;
if (has_strings()) {
for (auto string : *strings()) {
if (string.second->IsEmpty()) {
empty_string = string.second;
} else {
alternatives->Add(string.second, zone);
}
}
}
if (!ranges()->is_empty()) {
// In unicode sets mode case folding has to be done at precise locations
// (e.g. before building complements).
// It is therefore the parsers responsibility to case fold (sub-) ranges
// before creating ClassSetOperands.
alternatives->Add(zone->template New<RegExpClassRanges>(
zone, ranges(), RegExpClassRanges::IS_CASE_FOLDED),
zone);
}
if (empty_string != nullptr) {
alternatives->Add(empty_string, zone);
}
RegExpTree* node = nullptr;
if (size == 1) {
DCHECK_EQ(alternatives->length(), 1);
node = alternatives->first();
} else {
node = zone->template New<RegExpDisjunction>(alternatives);
}
return node->ToNode(compiler, on_success);
}
RegExpNode* RegExpClassSetExpression::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
Zone* zone = compiler->zone();
ZoneList<CharacterRange>* temp_ranges =
zone->template New<ZoneList<CharacterRange>>(4, zone);
RegExpClassSetOperand* root = ComputeExpression(this, temp_ranges, zone);
return root->ToNode(compiler, on_success);
}
void RegExpClassSetOperand::Union(RegExpClassSetOperand* other, Zone* zone) {
ranges()->AddAll(*other->ranges(), zone);
if (other->has_strings()) {
if (strings_ == nullptr) {
strings_ = zone->template New<CharacterClassStrings>(zone);
}
strings()->insert(other->strings()->begin(), other->strings()->end());
}
}
void RegExpClassSetOperand::Intersect(RegExpClassSetOperand* other,
ZoneList<CharacterRange>* temp_ranges,
Zone* zone) {
CharacterRange::Intersect(ranges(), other->ranges(), temp_ranges, zone);
std::swap(*ranges(), *temp_ranges);
temp_ranges->Rewind(0);
if (has_strings()) {
if (!other->has_strings()) {
strings()->clear();
} else {
for (auto iter = strings()->begin(); iter != strings()->end();) {
if (other->strings()->find(iter->first) == other->strings()->end()) {
iter = strings()->erase(iter);
} else {
iter++;
}
}
}
}
}
void RegExpClassSetOperand::Subtract(RegExpClassSetOperand* other,
ZoneList<CharacterRange>* temp_ranges,
Zone* zone) {
CharacterRange::Subtract(ranges(), other->ranges(), temp_ranges, zone);
std::swap(*ranges(), *temp_ranges);
temp_ranges->Rewind(0);
if (has_strings() && other->has_strings()) {
for (auto iter = strings()->begin(); iter != strings()->end();) {
if (other->strings()->find(iter->first) != other->strings()->end()) {
iter = strings()->erase(iter);
} else {
iter++;
}
}
}
}
// static
RegExpClassSetOperand* RegExpClassSetExpression::ComputeExpression(
RegExpTree* root, ZoneList<CharacterRange>* temp_ranges, Zone* zone) {
DCHECK(temp_ranges->is_empty());
if (root->IsClassSetOperand()) {
return root->AsClassSetOperand();
}
DCHECK(root->IsClassSetExpression());
RegExpClassSetExpression* node = root->AsClassSetExpression();
RegExpClassSetOperand* result =
ComputeExpression(node->operands()->at(0), temp_ranges, zone);
switch (node->operation()) {
case OperationType::kUnion: {
for (int i = 1; i < node->operands()->length(); i++) {
RegExpClassSetOperand* op =
ComputeExpression(node->operands()->at(i), temp_ranges, zone);
result->Union(op, zone);
}
CharacterRange::Canonicalize(result->ranges());
break;
}
case OperationType::kIntersection: {
for (int i = 1; i < node->operands()->length(); i++) {
RegExpClassSetOperand* op =
ComputeExpression(node->operands()->at(i), temp_ranges, zone);
result->Intersect(op, temp_ranges, zone);
}
break;
}
case OperationType::kSubtraction: {
for (int i = 1; i < node->operands()->length(); i++) {
RegExpClassSetOperand* op =
ComputeExpression(node->operands()->at(i), temp_ranges, zone);
result->Subtract(op, temp_ranges, zone);
}
break;
}
}
if (node->is_negated()) {
DCHECK(!result->has_strings());
CharacterRange::Negate(result->ranges(), temp_ranges, zone);
std::swap(*result->ranges(), *temp_ranges);
temp_ranges->Rewind(0);
node->is_negated_ = false;
}
// Store the result as single operand of the current node.
node->operands()->Set(0, result);
node->operands()->Rewind(1);
return result;
}
namespace {
int CompareFirstChar(RegExpTree* const* a, RegExpTree* const* b) {
RegExpAtom* atom1 = (*a)->AsAtom();
RegExpAtom* atom2 = (*b)->AsAtom();
base::uc16 character1 = atom1->data().at(0);
base::uc16 character2 = atom2->data().at(0);
if (character1 < character2) return -1;
if (character1 > character2) return 1;
return 0;
}
#ifdef V8_INTL_SUPPORT
int CompareCaseInsensitive(const icu::UnicodeString& a,
const icu::UnicodeString& b) {
return a.caseCompare(b, U_FOLD_CASE_DEFAULT);
}
int CompareFirstCharCaseInsensitive(RegExpTree* const* a,
RegExpTree* const* b) {
RegExpAtom* atom1 = (*a)->AsAtom();
RegExpAtom* atom2 = (*b)->AsAtom();
return CompareCaseInsensitive(icu::UnicodeString{atom1->data().at(0)},
icu::UnicodeString{atom2->data().at(0)});
}
bool Equals(bool ignore_case, const icu::UnicodeString& a,
const icu::UnicodeString& b) {
if (a == b) return true;
if (ignore_case) return CompareCaseInsensitive(a, b) == 0;
return false; // Case-sensitive equality already checked above.
}
bool CharAtEquals(bool ignore_case, int index, const RegExpAtom* a,
const RegExpAtom* b) {
return Equals(ignore_case, a->data().at(index), b->data().at(index));
}
#else
unibrow::uchar Canonical(
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
unibrow::uchar c) {
unibrow::uchar chars[unibrow::Ecma262Canonicalize::kMaxWidth];
int length = canonicalize->get(c, '\0', chars);
DCHECK_LE(length, 1);
unibrow::uchar canonical = c;
if (length == 1) canonical = chars[0];
return canonical;
}
int CompareCaseInsensitive(
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
unibrow::uchar a, unibrow::uchar b) {
if (a == b) return 0;
if (a >= 'a' || b >= 'a') {
a = Canonical(canonicalize, a);
b = Canonical(canonicalize, b);
}
return static_cast<int>(a) - static_cast<int>(b);
}
int CompareFirstCharCaseInsensitive(
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
RegExpTree* const* a, RegExpTree* const* b) {
RegExpAtom* atom1 = (*a)->AsAtom();
RegExpAtom* atom2 = (*b)->AsAtom();
return CompareCaseInsensitive(canonicalize, atom1->data().at(0),
atom2->data().at(0));
}
bool Equals(bool ignore_case,
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
unibrow::uchar a, unibrow::uchar b) {
if (a == b) return true;
if (ignore_case) {
return CompareCaseInsensitive(canonicalize, a, b) == 0;
}
return false; // Case-sensitive equality already checked above.
}
bool CharAtEquals(bool ignore_case,
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
int index, const RegExpAtom* a, const RegExpAtom* b) {
return Equals(ignore_case, canonicalize, a->data().at(index),
b->data().at(index));
}
#endif // V8_INTL_SUPPORT
} // namespace
// We can stable sort runs of atoms, since the order does not matter if they
// start with different characters.
// Returns true if any consecutive atoms were found.
bool RegExpDisjunction::SortConsecutiveAtoms(RegExpCompiler* compiler) {
ZoneList<RegExpTree*>* alternatives = this->alternatives();
int length = alternatives->length();
bool found_consecutive_atoms = false;
for (int i = 0; i < length; i++) {
while (i < length) {
RegExpTree* alternative = alternatives->at(i);
if (alternative->IsAtom()) break;
i++;
}
// i is length or it is the index of an atom.
if (i == length) break;
int first_atom = i;
i++;
while (i < length) {
RegExpTree* alternative = alternatives->at(i);
if (!alternative->IsAtom()) break;
i++;
}
// Sort atoms to get ones with common prefixes together.
// This step is more tricky if we are in a case-independent regexp,
// because it would change /is|I/ to /I|is/, and order matters when
// the regexp parts don't match only disjoint starting points. To fix
// this we have a version of CompareFirstChar that uses case-
// independent character classes for comparison.
DCHECK_LT(first_atom, alternatives->length());
DCHECK_LE(i, alternatives->length());
DCHECK_LE(first_atom, i);
if (IsIgnoreCase(compiler->flags())) {
#ifdef V8_INTL_SUPPORT
alternatives->StableSort(CompareFirstCharCaseInsensitive, first_atom,
i - first_atom);
#else
unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
compiler->isolate()->regexp_macro_assembler_canonicalize();
auto compare_closure = [canonicalize](RegExpTree* const* a,
RegExpTree* const* b) {
return CompareFirstCharCaseInsensitive(canonicalize, a, b);
};
alternatives->StableSort(compare_closure, first_atom, i - first_atom);
#endif // V8_INTL_SUPPORT
} else {
alternatives->StableSort(CompareFirstChar, first_atom, i - first_atom);
}
if (i - first_atom > 1) found_consecutive_atoms = true;
}
return found_consecutive_atoms;
}
// Optimizes ab|ac|az to a(?:b|c|d).
void RegExpDisjunction::RationalizeConsecutiveAtoms(RegExpCompiler* compiler) {
Zone* zone = compiler->zone();
ZoneList<RegExpTree*>* alternatives = this->alternatives();
int length = alternatives->length();
const bool ignore_case = IsIgnoreCase(compiler->flags());
int write_posn = 0;
int i = 0;
while (i < length) {
RegExpTree* alternative = alternatives->at(i);
if (!alternative->IsAtom()) {
alternatives->at(write_posn++) = alternatives->at(i);
i++;
continue;
}
RegExpAtom* const atom = alternative->AsAtom();
#ifdef V8_INTL_SUPPORT
icu::UnicodeString common_prefix(atom->data().at(0));
#else
unibrow::Mapping<unibrow::Ecma262Canonicalize>* const canonicalize =
compiler->isolate()->regexp_macro_assembler_canonicalize();
unibrow::uchar common_prefix = atom->data().at(0);
if (ignore_case) {
common_prefix = Canonical(canonicalize, common_prefix);
}
#endif // V8_INTL_SUPPORT
int first_with_prefix = i;
int prefix_length = atom->length();
i++;
while (i < length) {
alternative = alternatives->at(i);
if (!alternative->IsAtom()) break;
RegExpAtom* const alt_atom = alternative->AsAtom();
#ifdef V8_INTL_SUPPORT
icu::UnicodeString new_prefix(alt_atom->data().at(0));
if (!Equals(ignore_case, new_prefix, common_prefix)) break;
#else
unibrow::uchar new_prefix = alt_atom->data().at(0);
if (!Equals(ignore_case, canonicalize, new_prefix, common_prefix)) break;
#endif // V8_INTL_SUPPORT
prefix_length = std::min(prefix_length, alt_atom->length());
i++;
}
if (i > first_with_prefix + 2) {
// Found worthwhile run of alternatives with common prefix of at least one
// character. The sorting function above did not sort on more than one
// character for reasons of correctness, but there may still be a longer
// common prefix if the terms were similar or presorted in the input.
// Find out how long the common prefix is.
int run_length = i - first_with_prefix;
RegExpAtom* const alt_atom =
alternatives->at(first_with_prefix)->AsAtom();
for (int j = 1; j < run_length && prefix_length > 1; j++) {
RegExpAtom* old_atom =
alternatives->at(j + first_with_prefix)->AsAtom();
for (int k = 1; k < prefix_length; k++) {
#ifdef V8_INTL_SUPPORT
if (!CharAtEquals(ignore_case, k, alt_atom, old_atom)) {
#else
if (!CharAtEquals(ignore_case, canonicalize, k, alt_atom, old_atom)) {
#endif // V8_INTL_SUPPORT
prefix_length = k;
break;
}
}
}
RegExpAtom* prefix =
zone->New<RegExpAtom>(alt_atom->data().SubVector(0, prefix_length));
ZoneList<RegExpTree*>* pair = zone->New<ZoneList<RegExpTree*>>(2, zone);
pair->Add(prefix, zone);
ZoneList<RegExpTree*>* suffixes =
zone->New<ZoneList<RegExpTree*>>(run_length, zone);
for (int j = 0; j < run_length; j++) {
RegExpAtom* old_atom =
alternatives->at(j + first_with_prefix)->AsAtom();
int len = old_atom->length();
if (len == prefix_length) {
suffixes->Add(zone->New<RegExpEmpty>(), zone);
} else {
RegExpTree* suffix = zone->New<RegExpAtom>(
old_atom->data().SubVector(prefix_length, old_atom->length()));
suffixes->Add(suffix, zone);
}
}
pair->Add(zone->New<RegExpDisjunction>(suffixes), zone);
alternatives->at(write_posn++) = zone->New<RegExpAlternative>(pair);
} else {
// Just copy any non-worthwhile alternatives.
for (int j = first_with_prefix; j < i; j++) {
alternatives->at(write_posn++) = alternatives->at(j);
}
}
}
alternatives->Rewind(write_posn); // Trim end of array.
}
// Optimizes b|c|z to [bcz].
void RegExpDisjunction::FixSingleCharacterDisjunctions(
RegExpCompiler* compiler) {
Zone* zone = compiler->zone();
ZoneList<RegExpTree*>* alternatives = this->alternatives();
int length = alternatives->length();
int write_posn = 0;
int i = 0;
while (i < length) {
RegExpTree* alternative = alternatives->at(i);
if (!alternative->IsAtom()) {
alternatives->at(write_posn++) = alternatives->at(i);
i++;
continue;
}
RegExpAtom* const atom = alternative->AsAtom();
if (atom->length() != 1) {
alternatives->at(write_posn++) = alternatives->at(i);
i++;
continue;
}
const RegExpFlags flags = compiler->flags();
DCHECK_IMPLIES(IsEitherUnicode(flags),
!unibrow::Utf16::IsLeadSurrogate(atom->data().at(0)));
bool contains_trail_surrogate =
unibrow::Utf16::IsTrailSurrogate(atom->data().at(0));
int first_in_run = i;
i++;
// Find a run of single-character atom alternatives that have identical
// flags (case independence and unicode-ness).
while (i < length) {
alternative = alternatives->at(i);
if (!alternative->IsAtom()) break;
RegExpAtom* const alt_atom = alternative->AsAtom();
if (alt_atom->length() != 1) break;
DCHECK_IMPLIES(IsEitherUnicode(flags),
!unibrow::Utf16::IsLeadSurrogate(alt_atom->data().at(0)));
contains_trail_surrogate |=
unibrow::Utf16::IsTrailSurrogate(alt_atom->data().at(0));
i++;
}
if (i > first_in_run + 1) {
// Found non-trivial run of single-character alternatives.
int run_length = i - first_in_run;
ZoneList<CharacterRange>* ranges =
zone->New<ZoneList<CharacterRange>>(2, zone);
for (int j = 0; j < run_length; j++) {
RegExpAtom* old_atom = alternatives->at(j + first_in_run)->AsAtom();
DCHECK_EQ(old_atom->length(), 1);
ranges->Add(CharacterRange::Singleton(old_atom->data().at(0)), zone);
}
RegExpClassRanges::ClassRangesFlags class_ranges_flags;
if (IsEitherUnicode(flags) && contains_trail_surrogate) {
class_ranges_flags = RegExpClassRanges::CONTAINS_SPLIT_SURROGATE;
}
alternatives->at(write_posn++) =
zone->New<RegExpClassRanges>(zone, ranges, class_ranges_flags);
} else {
// Just copy any trivial alternatives.
for (int j = first_in_run; j < i; j++) {
alternatives->at(write_posn++) = alternatives->at(j);
}
}
}
alternatives->Rewind(write_posn); // Trim end of array.
}
RegExpNode* RegExpDisjunction::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
compiler->ToNodeMaybeCheckForStackOverflow();
ZoneList<RegExpTree*>* alternatives = this->alternatives();
if (alternatives->length() > 2) {
bool found_consecutive_atoms = SortConsecutiveAtoms(compiler);
if (found_consecutive_atoms) RationalizeConsecutiveAtoms(compiler);
FixSingleCharacterDisjunctions(compiler);
if (alternatives->length() == 1) {
return alternatives->at(0)->ToNode(compiler, on_success);
}
}
int length = alternatives->length();
ChoiceNode* result =
compiler->zone()->New<ChoiceNode>(length, compiler->zone());
for (int i = 0; i < length; i++) {
GuardedAlternative alternative(
alternatives->at(i)->ToNode(compiler, on_success));
result->AddAlternative(alternative);
}
return result;
}
RegExpNode* RegExpQuantifier::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
return ToNode(min(), max(), is_greedy(), body(), compiler, on_success);
}
namespace {
// Desugar \b to (?<=\w)(?=\W)|(?<=\W)(?=\w) and
// \B to (?<=\w)(?=\w)|(?<=\W)(?=\W)
RegExpNode* BoundaryAssertionAsLookaround(RegExpCompiler* compiler,
RegExpNode* on_success,
RegExpAssertion::Type type) {
CHECK(NeedsUnicodeCaseEquivalents(compiler->flags()));
Zone* zone = compiler->zone();
ZoneList<CharacterRange>* word_range =
zone->New<ZoneList<CharacterRange>>(2, zone);
CharacterRange::AddClassEscape(StandardCharacterSet::kWord, word_range, true,
zone);
int stack_register = compiler->UnicodeLookaroundStackRegister();
int position_register = compiler->UnicodeLookaroundPositionRegister();
ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
// Add two choices. The (non-)boundary could start with a word or
// a non-word-character.
for (int i = 0; i < 2; i++) {
bool lookbehind_for_word = i == 0;
bool lookahead_for_word =
(type == RegExpAssertion::Type::BOUNDARY) ^ lookbehind_for_word;
// Look to the left.
RegExpLookaround::Builder lookbehind(lookbehind_for_word, on_success,
stack_register, position_register);
RegExpNode* backward = TextNode::CreateForCharacterRanges(
zone, word_range, true, lookbehind.on_match_success());
// Look to the right.
RegExpLookaround::Builder lookahead(lookahead_for_word,
lookbehind.ForMatch(backward),
stack_register, position_register);
RegExpNode* forward = TextNode::CreateForCharacterRanges(
zone, word_range, false, lookahead.on_match_success());
result->AddAlternative(GuardedAlternative(lookahead.ForMatch(forward)));
}
return result;
}
} // anonymous namespace
RegExpNode* RegExpAssertion::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
NodeInfo info;
Zone* zone = compiler->zone();
switch (assertion_type()) {
case Type::START_OF_LINE:
return AssertionNode::AfterNewline(on_success);
case Type::START_OF_INPUT:
return AssertionNode::AtStart(on_success);
case Type::BOUNDARY:
return NeedsUnicodeCaseEquivalents(compiler->flags())
? BoundaryAssertionAsLookaround(compiler, on_success,
Type::BOUNDARY)
: AssertionNode::AtBoundary(on_success);
case Type::NON_BOUNDARY:
return NeedsUnicodeCaseEquivalents(compiler->flags())
? BoundaryAssertionAsLookaround(compiler, on_success,
Type::NON_BOUNDARY)
: AssertionNode::AtNonBoundary(on_success);
case Type::END_OF_INPUT:
return AssertionNode::AtEnd(on_success);
case Type::END_OF_LINE: {
// Compile $ in multiline regexps as an alternation with a positive
// lookahead in one side and an end-of-input on the other side.
// We need two registers for the lookahead.
int stack_pointer_register = compiler->AllocateRegister();
int position_register = compiler->AllocateRegister();
// The ChoiceNode to distinguish between a newline and end-of-input.
ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
// Create a newline atom.
ZoneList<CharacterRange>* newline_ranges =
zone->New<ZoneList<CharacterRange>>(3, zone);
CharacterRange::AddClassEscape(StandardCharacterSet::kLineTerminator,
newline_ranges, false, zone);
RegExpClassRanges* newline_atom =
zone->New<RegExpClassRanges>(StandardCharacterSet::kLineTerminator);
TextNode* newline_matcher =
zone->New<TextNode>(newline_atom, false,
ActionNode::PositiveSubmatchSuccess(
stack_pointer_register, position_register,
0, // No captures inside.
-1, // Ignored if no captures.
on_success));
// Create an end-of-input matcher.
RegExpNode* end_of_line = ActionNode::BeginPositiveSubmatch(
stack_pointer_register, position_register, newline_matcher);
// Add the two alternatives to the ChoiceNode.
GuardedAlternative eol_alternative(end_of_line);
result->AddAlternative(eol_alternative);
GuardedAlternative end_alternative(AssertionNode::AtEnd(on_success));
result->AddAlternative(end_alternative);
return result;
}
default:
UNREACHABLE();
}
}
RegExpNode* RegExpBackReference::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
RegExpNode* backref_node = on_success;
// Only one of the captures in the list can actually match. Since
// back-references to unmatched captures are treated as empty, we can simply
// create back-references to all possible captures.
for (auto capture : *captures()) {
backref_node = compiler->zone()->New<BackReferenceNode>(
RegExpCapture::StartRegister(capture->index()),
RegExpCapture::EndRegister(capture->index()), compiler->read_backward(),
backref_node);
}
return backref_node;
}
RegExpNode* RegExpEmpty::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
return on_success;
}
namespace {
class V8_NODISCARD ModifiersScope {
public:
ModifiersScope(RegExpCompiler* compiler, RegExpFlags flags)
: compiler_(compiler), previous_flags_(compiler->flags()) {
compiler->set_flags(flags);
}
~ModifiersScope() { compiler_->set_flags(previous_flags_); }
private:
RegExpCompiler* compiler_;
const RegExpFlags previous_flags_;
};
} // namespace
RegExpNode* RegExpGroup::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
// If no flags are modified, simply convert and return the body.
if (flags() == compiler->flags()) {
return body_->ToNode(compiler, on_success);
}
// Reset flags for successor node.
const RegExpFlags old_flags = compiler->flags();
on_success = ActionNode::ModifyFlags(old_flags, on_success);
// Convert body using modifier.
ModifiersScope modifiers_scope(compiler, flags());
RegExpNode* body = body_->ToNode(compiler, on_success);
// Wrap body into modifier node.
RegExpNode* modified_body = ActionNode::ModifyFlags(flags(), body);
return modified_body;
}
RegExpLookaround::Builder::Builder(bool is_positive, RegExpNode* on_success,
int stack_pointer_register,
int position_register,
int capture_register_count,
int capture_register_start)
: is_positive_(is_positive),
on_success_(on_success),
stack_pointer_register_(stack_pointer_register),
position_register_(position_register) {
if (is_positive_) {
on_match_success_ = ActionNode::PositiveSubmatchSuccess(
stack_pointer_register, position_register, capture_register_count,
capture_register_start, on_success_);
} else {
Zone* zone = on_success_->zone();
on_match_success_ = zone->New<NegativeSubmatchSuccess>(
stack_pointer_register, position_register, capture_register_count,
capture_register_start, zone);
}
}
RegExpNode* RegExpLookaround::Builder::ForMatch(RegExpNode* match) {
if (is_positive_) {
return ActionNode::BeginPositiveSubmatch(stack_pointer_register_,
position_register_, match);
} else {
Zone* zone = on_success_->zone();
// We use a ChoiceNode to represent the negative lookaround. The first
// alternative is the negative match. On success, the end node backtracks.
// On failure, the second alternative is tried and leads to success.
// NegativeLookaheadChoiceNode is a special ChoiceNode that ignores the
// first exit when calculating quick checks.
ChoiceNode* choice_node = zone->New<NegativeLookaroundChoiceNode>(
GuardedAlternative(match), GuardedAlternative(on_success_), zone);
return ActionNode::BeginNegativeSubmatch(stack_pointer_register_,
position_register_, choice_node);
}
}
RegExpNode* RegExpLookaround::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
int stack_pointer_register = compiler->AllocateRegister();
int position_register = compiler->AllocateRegister();
const int registers_per_capture = 2;
const int register_of_first_capture = 2;
int register_count = capture_count_ * registers_per_capture;
int register_start =
register_of_first_capture + capture_from_ * registers_per_capture;
RegExpNode* result;
bool was_reading_backward = compiler->read_backward();
compiler->set_read_backward(type() == LOOKBEHIND);
Builder builder(is_positive(), on_success, stack_pointer_register,
position_register, register_count, register_start);
RegExpNode* match = body_->ToNode(compiler, builder.on_match_success());
result = builder.ForMatch(match);
compiler->set_read_backward(was_reading_backward);
return result;
}
RegExpNode* RegExpCapture::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
return ToNode(body(), index(), compiler, on_success);
}
RegExpNode* RegExpCapture::ToNode(RegExpTree* body, int index,
RegExpCompiler* compiler,
RegExpNode* on_success) {
DCHECK_NOT_NULL(body);
int start_reg = RegExpCapture::StartRegister(index);
int end_reg = RegExpCapture::EndRegister(index);
if (compiler->read_backward()) std::swap(start_reg, end_reg);
RegExpNode* store_end = ActionNode::StorePosition(end_reg, true, on_success);
RegExpNode* body_node = body->ToNode(compiler, store_end);
return ActionNode::StorePosition(start_reg, true, body_node);
}
namespace {
class AssertionSequenceRewriter final {
public:
// TODO(jgruber): Consider moving this to a separate AST tree rewriter pass
// instead of sprinkling rewrites into the AST->Node conversion process.
static void MaybeRewrite(ZoneList<RegExpTree*>* terms, Zone* zone) {
AssertionSequenceRewriter rewriter(terms, zone);
static constexpr int kNoIndex = -1;
int from = kNoIndex;
for (int i = 0; i < terms->length(); i++) {
RegExpTree* t = terms->at(i);
if (from == kNoIndex && t->IsAssertion()) {
from = i; // Start a sequence.
} else if (from != kNoIndex && !t->IsAssertion()) {
// Terminate and process the sequence.
if (i - from > 1) rewriter.Rewrite(from, i);
from = kNoIndex;
}
}
if (from != kNoIndex && terms->length() - from > 1) {
rewriter.Rewrite(from, terms->length());
}
}
// All assertions are zero width. A consecutive sequence of assertions is
// order-independent. There's two ways we can optimize here:
// 1. fold all identical assertions.
// 2. if any assertion combinations are known to fail (e.g. \b\B), the entire
// sequence fails.
void Rewrite(int from, int to) {
DCHECK_GT(to, from + 1);
// Bitfield of all seen assertions.
uint32_t seen_assertions = 0;
static_assert(static_cast<int>(RegExpAssertion::Type::LAST_ASSERTION_TYPE) <
kUInt32Size * kBitsPerByte);
for (int i = from; i < to; i++) {
RegExpAssertion* t = terms_->at(i)->AsAssertion();
const uint32_t bit = 1 << static_cast<int>(t->assertion_type());
if (seen_assertions & bit) {
// Fold duplicates.
terms_->Set(i, zone_->New<RegExpEmpty>());
}
seen_assertions |= bit;
}
// Collapse failures.
const uint32_t always_fails_mask =
1 << static_cast<int>(RegExpAssertion::Type::BOUNDARY) |
1 << static_cast<int>(RegExpAssertion::Type::NON_BOUNDARY);
if ((seen_assertions & always_fails_mask) == always_fails_mask) {
ReplaceSequenceWithFailure(from, to);
}
}
void ReplaceSequenceWithFailure(int from, int to) {
// Replace the entire sequence with a single node that always fails.
// TODO(jgruber): Consider adding an explicit Fail kind. Until then, the
// negated '*' (everything) range serves the purpose.
ZoneList<CharacterRange>* ranges =
zone_->New<ZoneList<CharacterRange>>(0, zone_);
RegExpClassRanges* cc = zone_->New<RegExpClassRanges>(zone_, ranges);
terms_->Set(from, cc);
// Zero out the rest.
RegExpEmpty* empty = zone_->New<RegExpEmpty>();
for (int i = from + 1; i < to; i++) terms_->Set(i, empty);
}
private:
AssertionSequenceRewriter(ZoneList<RegExpTree*>* terms, Zone* zone)
: zone_(zone), terms_(terms) {}
Zone* zone_;
ZoneList<RegExpTree*>* terms_;
};
} // namespace
RegExpNode* RegExpAlternative::ToNode(RegExpCompiler* compiler,
RegExpNode* on_success) {
compiler->ToNodeMaybeCheckForStackOverflow();
ZoneList<RegExpTree*>* children = nodes();
AssertionSequenceRewriter::MaybeRewrite(children, compiler->zone());
RegExpNode* current = on_success;
if (compiler->read_backward()) {
for (int i = 0; i < children->length(); i++) {
current = children->at(i)->ToNode(compiler, current);
}
} else {
for (int i = children->length() - 1; i >= 0; i--) {
current = children->at(i)->ToNode(compiler, current);
}
}
return current;
}
namespace {
void AddClass(const int* elmv, int elmc, ZoneList<CharacterRange>* ranges,
Zone* zone) {
elmc--;
DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
for (int i = 0; i < elmc; i += 2) {
DCHECK(elmv[i] < elmv[i + 1]);
ranges->Add(CharacterRange::Range(elmv[i], elmv[i + 1] - 1), zone);
}
}
void AddClassNegated(const int* elmv, int elmc,
ZoneList<CharacterRange>* ranges, Zone* zone) {
elmc--;
DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
DCHECK_NE(0x0000, elmv[0]);
DCHECK_NE(kMaxCodePoint, elmv[elmc - 1]);
base::uc16 last = 0x0000;
for (int i = 0; i < elmc; i += 2) {
DCHECK(last <= elmv[i] - 1);
DCHECK(elmv[i] < elmv[i + 1]);
ranges->Add(CharacterRange::Range(last, elmv[i] - 1), zone);
last = elmv[i + 1];
}
ranges->Add(CharacterRange::Range(last, kMaxCodePoint), zone);
}
} // namespace
void CharacterRange::AddClassEscape(StandardCharacterSet standard_character_set,
ZoneList<CharacterRange>* ranges,
bool add_unicode_case_equivalents,
Zone* zone) {
if (add_unicode_case_equivalents &&
(standard_character_set == StandardCharacterSet::kWord ||
standard_character_set == StandardCharacterSet::kNotWord)) {
// See #sec-runtime-semantics-wordcharacters-abstract-operation
// In case of unicode and ignore_case, we need to create the closure over
// case equivalent characters before negating.
ZoneList<CharacterRange>* new_ranges =
zone->New<ZoneList<CharacterRange>>(2, zone);
AddClass(kWordRanges, kWordRangeCount, new_ranges, zone);
AddUnicodeCaseEquivalents(new_ranges, zone);
if (standard_character_set == StandardCharacterSet::kNotWord) {
ZoneList<CharacterRange>* negated =
zone->New<ZoneList<CharacterRange>>(2, zone);
CharacterRange::Negate(new_ranges, negated, zone);
new_ranges = negated;
}
ranges->AddAll(*new_ranges, zone);
return;
}
switch (standard_character_set) {
case StandardCharacterSet::kWhitespace:
AddClass(kSpaceRanges, kSpaceRangeCount, ranges, zone);
break;
case StandardCharacterSet::kNotWhitespace:
AddClassNegated(kSpaceRanges, kSpaceRangeCount, ranges, zone);
break;
case StandardCharacterSet::kWord:
AddClass(kWordRanges, kWordRangeCount, ranges, zone);
break;
case StandardCharacterSet::kNotWord:
AddClassNegated(kWordRanges, kWordRangeCount, ranges, zone);
break;
case StandardCharacterSet::kDigit:
AddClass(kDigitRanges, kDigitRangeCount, ranges, zone);
break;
case StandardCharacterSet::kNotDigit:
AddClassNegated(kDigitRanges, kDigitRangeCount, ranges, zone);
break;
// This is the set of characters matched by the $ and ^ symbols
// in multiline mode.
case StandardCharacterSet::kLineTerminator:
AddClass(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges, zone);
break;
case StandardCharacterSet::kNotLineTerminator:
AddClassNegated(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges,
zone);
break;
// This is not a character range as defined by the spec but a
// convenient shorthand for a character class that matches any
// character.
case StandardCharacterSet::kEverything:
ranges->Add(CharacterRange::Everything(), zone);
break;
}
}
// static
void CharacterRange::AddCaseEquivalents(Isolate* isolate, Zone* zone,
ZoneList<CharacterRange>* ranges,
bool is_one_byte) {
CharacterRange::Canonicalize(ranges);
int range_count = ranges->length();
#ifdef V8_INTL_SUPPORT
icu::UnicodeSet others;
for (int i = 0; i < range_count; i++) {
CharacterRange range = ranges->at(i);
base::uc32 from = range.from();
if (from > kMaxUtf16CodeUnit) continue;
base::uc32 to = std::min({range.to(), kMaxUtf16CodeUnitU});
// Nothing to be done for surrogates.
if (from >= kLeadSurrogateStart && to <= kTrailSurrogateEnd) continue;
if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
if (from > kMaxOneByteCharCode) continue;
if (to > kMaxOneByteCharCode) to = kMaxOneByteCharCode;
}
others.add(from, to);
}
// Compute the set of additional characters that should be added,
// using UnicodeSet::closeOver. ECMA 262 defines slightly different
// case-folding rules than Unicode, so some characters that are
// added by closeOver do not match anything other than themselves in
// JS. For example, 'ſ' (U+017F LATIN SMALL LETTER LONG S) is the
// same case-insensitive character as 's' or 'S' according to
// Unicode, but does not match any other character in JS. To handle
// this case, we add such characters to the IgnoreSet and filter
// them out. We filter twice: once before calling closeOver (to
// prevent 'ſ' from adding 's'), and once after calling closeOver
// (to prevent 's' from adding 'ſ'). See regexp/special-case.h for
// more information.
icu::UnicodeSet already_added(others);
others.removeAll(RegExpCaseFolding::IgnoreSet());
others.closeOver(USET_CASE_INSENSITIVE);
others.removeAll(RegExpCaseFolding::IgnoreSet());
others.removeAll(already_added);
// Add others to the ranges
for (int32_t i = 0; i < others.getRangeCount(); i++) {
UChar32 from = others.getRangeStart(i);
UChar32 to = others.getRangeEnd(i);
if (from == to) {
ranges->Add(CharacterRange::Singleton(from), zone);
} else {
ranges->Add(CharacterRange::Range(from, to), zone);
}
}
#else
for (int i = 0; i < range_count; i++) {
CharacterRange range = ranges->at(i);
base::uc32 bottom = range.from();
if (bottom > kMaxUtf16CodeUnit) continue;
base::uc32 top = std::min({range.to(), kMaxUtf16CodeUnitU});
// Nothing to be done for surrogates.
if (bottom >= kLeadSurrogateStart && top <= kTrailSurrogateEnd) continue;
if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
if (bottom > kMaxOneByteCharCode) continue;
if (top > kMaxOneByteCharCode) top = kMaxOneByteCharCode;
}
unibrow::uchar chars[unibrow::Ecma262UnCanonicalize::kMaxWidth];
if (top == bottom) {
// If this is a singleton we just expand the one character.
int length = isolate->jsregexp_uncanonicalize()->get(bottom, '\0', chars);
for (int i = 0; i < length; i++) {
base::uc32 chr = chars[i];
if (chr != bottom) {
ranges->Add(CharacterRange::Singleton(chars[i]), zone);
}
}
} else {
// If this is a range we expand the characters block by block, expanding
// contiguous subranges (blocks) one at a time. The approach is as
// follows. For a given start character we look up the remainder of the
// block that contains it (represented by the end point), for instance we
// find 'z' if the character is 'c'. A block is characterized by the
// property that all characters uncanonicalize in the same way, except
// that each entry in the result is incremented by the distance from the
// first element. So a-z is a block because 'a' uncanonicalizes to ['a',
// 'A'] and the k'th letter uncanonicalizes to ['a' + k, 'A' + k]. Once
// we've found the end point we look up its uncanonicalization and
// produce a range for each element. For instance for [c-f] we look up
// ['z', 'Z'] and produce [c-f] and [C-F]. We then only add a range if
// it is not already contained in the input, so [c-f] will be skipped but
// [C-F] will be added. If this range is not completely contained in a
// block we do this for all the blocks covered by the range (handling
// characters that is not in a block as a "singleton block").
unibrow::uchar equivalents[unibrow::Ecma262UnCanonicalize::kMaxWidth];
base::uc32 pos = bottom;
while (pos <= top) {
int length =
isolate->jsregexp_canonrange()->get(pos, '\0', equivalents);
base::uc32 block_end;
if (length == 0) {
block_end = pos;
} else {
DCHECK_EQ(1, length);
block_end = equivalents[0];
}
int end = (block_end > top) ? top : block_end;
length = isolate->jsregexp_uncanonicalize()->get(block_end, '\0',
equivalents);
for (int i = 0; i < length; i++) {
base::uc32 c = equivalents[i];
base::uc32 range_from = c - (block_end - pos);
base::uc32 range_to = c - (block_end - end);
if (!(bottom <= range_from && range_to <= top)) {
ranges->Add(CharacterRange::Range(range_from, range_to), zone);
}
}
pos = end + 1;
}
}
}
#endif // V8_INTL_SUPPORT
}
bool CharacterRange::IsCanonical(const ZoneList<CharacterRange>* ranges) {
DCHECK_NOT_NULL(ranges);
int n = ranges->length();
if (n <= 1) return true;
base::uc32 max = ranges->at(0).to();
for (int i = 1; i < n; i++) {
CharacterRange next_range = ranges->at(i);
if (next_range.from() <= max + 1) return false;
max = next_range.to();
}
return true;
}
ZoneList<CharacterRange>* CharacterSet::ranges(Zone* zone) {
if (ranges_ == nullptr) {
ranges_ = zone->New<ZoneList<CharacterRange>>(2, zone);
CharacterRange::AddClassEscape(standard_set_type_.value(), ranges_, false,
zone);
}
return ranges_;
}
namespace {
// Move a number of elements in a zonelist to another position
// in the same list. Handles overlapping source and target areas.
void MoveRanges(ZoneList<CharacterRange>* list, int from, int to, int count) {
// Ranges are potentially overlapping.
if (from < to) {
for (int i = count - 1; i >= 0; i--) {
list->at(to + i) = list->at(from + i);
}
} else {
for (int i = 0; i < count; i++) {
list->at(to + i) = list->at(from + i);
}
}
}
int InsertRangeInCanonicalList(ZoneList<CharacterRange>* list, int count,
CharacterRange insert) {
// Inserts a range into list[0..count[, which must be sorted
// by from value and non-overlapping and non-adjacent, using at most
// list[0..count] for the result. Returns the number of resulting
// canonicalized ranges. Inserting a range may collapse existing ranges into
// fewer ranges, so the return value can be anything in the range 1..count+1.
base::uc32 from = insert.from();
base::uc32 to = insert.to();
int start_pos = 0;
int end_pos = count;
for (int i = count - 1; i >= 0; i--) {
CharacterRange current = list->at(i);
if (current.from() > to + 1) {
end_pos = i;
} else if (current.to() + 1 < from) {
start_pos = i + 1;
break;
}
}
// Inserted range overlaps, or is adjacent to, ranges at positions
// [start_pos..end_pos[. Ranges before start_pos or at or after end_pos are
// not affected by the insertion.
// If start_pos == end_pos, the range must be inserted before start_pos.
// if start_pos < end_pos, the entire range from start_pos to end_pos
// must be merged with the insert range.
if (start_pos == end_pos) {
// Insert between existing ranges at position start_pos.
if (start_pos < count) {
MoveRanges(list, start_pos, start_pos + 1, count - start_pos);
}
list->at(start_pos) = insert;
return count + 1;
}
if (start_pos + 1 == end_pos) {
// Replace single existing range at position start_pos.
CharacterRange to_replace = list->at(start_pos);
int new_from = std::min(to_replace.from(), from);
int new_to = std::max(to_replace.to(), to);
list->at(start_pos) = CharacterRange::Range(new_from, new_to);
return count;
}
// Replace a number of existing ranges from start_pos to end_pos - 1.
// Move the remaining ranges down.
int new_from = std::min(list->at(start_pos).from(), from);
int new_to = std::max(list->at(end_pos - 1).to(), to);
if (end_pos < count) {
MoveRanges(list, end_pos, start_pos + 1, count - end_pos);
}
list->at(start_pos) = CharacterRange::Range(new_from, new_to);
return count - (end_pos - start_pos) + 1;
}
} // namespace
void CharacterSet::Canonicalize() {
// Special/default classes are always considered canonical. The result
// of calling ranges() will be sorted.
if (ranges_ == nullptr) return;
CharacterRange::Canonicalize(ranges_);
}
// static
void CharacterRange::Canonicalize(ZoneList<CharacterRange>* character_ranges) {
if (character_ranges->length() <= 1) return;
// Check whether ranges are already canonical (increasing, non-overlapping,
// non-adjacent).
int n = character_ranges->length();
base::uc32 max = character_ranges->at(0).to();
int i = 1;
while (i < n) {
CharacterRange current = character_ranges->at(i);
if (current.from() <= max + 1) {
break;
}
max = current.to();
i++;
}
// Canonical until the i'th range. If that's all of them, we are done.
if (i == n) return;
// The ranges at index i and forward are not canonicalized. Make them so by
// doing the equivalent of insertion sort (inserting each into the previous
// list, in order).
// Notice that inserting a range can reduce the number of ranges in the
// result due to combining of adjacent and overlapping ranges.
int read = i; // Range to insert.
int num_canonical = i; // Length of canonicalized part of list.
do {
num_canonical = InsertRangeInCanonicalList(character_ranges, num_canonical,
character_ranges->at(read));
read++;
} while (read < n);
character_ranges->Rewind(num_canonical);
DCHECK(CharacterRange::IsCanonical(character_ranges));
}
// static
void CharacterRange::Negate(const ZoneList<CharacterRange>* ranges,
ZoneList<CharacterRange>* negated_ranges,
Zone* zone) {
DCHECK(CharacterRange::IsCanonical(ranges));
DCHECK_EQ(0, negated_ranges->length());
int range_count = ranges->length();
base::uc32 from = 0;
int i = 0;
if (range_count > 0 && ranges->at(0).from() == 0) {
from = ranges->at(0).to() + 1;
i = 1;
}
while (i < range_count) {
CharacterRange range = ranges->at(i);
negated_ranges->Add(CharacterRange::Range(from, range.from() - 1), zone);
from = range.to() + 1;
i++;
}
if (from < kMaxCodePoint) {
negated_ranges->Add(CharacterRange::Range(from, kMaxCodePoint), zone);
}
}
// static
void CharacterRange::Intersect(const ZoneList<CharacterRange>* lhs,
const ZoneList<CharacterRange>* rhs,
ZoneList<CharacterRange>* intersection,
Zone* zone) {
DCHECK(CharacterRange::IsCanonical(lhs));
DCHECK(CharacterRange::IsCanonical(rhs));
DCHECK_EQ(0, intersection->length());
int lhs_index = 0;
int rhs_index = 0;
while (lhs_index < lhs->length() && rhs_index < rhs->length()) {
// Skip non-overlapping ranges.
if (lhs->at(lhs_index).to() < rhs->at(rhs_index).from()) {
lhs_index++;
continue;
}
if (rhs->at(rhs_index).to() < lhs->at(lhs_index).from()) {
rhs_index++;
continue;
}
base::uc32 from =
std::max(lhs->at(lhs_index).from(), rhs->at(rhs_index).from());
base::uc32 to = std::min(lhs->at(lhs_index).to(), rhs->at(rhs_index).to());
intersection->Add(CharacterRange::Range(from, to), zone);
if (to == lhs->at(lhs_index).to()) {
lhs_index++;
} else {
rhs_index++;
}
}
DCHECK(IsCanonical(intersection));
}
namespace {
// Advance |index| and set |from| and |to| to the new range, if not out of
// bounds of |range|, otherwise |from| is set to a code point beyond the legal
// unicode character range.
void SafeAdvanceRange(const ZoneList<CharacterRange>* range, int* index,
base::uc32* from, base::uc32* to) {
++(*index);
if (*index < range->length()) {
*from = range->at(*index).from();
*to = range->at(*index).to();
} else {
*from = kMaxCodePoint + 1;
}
}
} // namespace
// static
void CharacterRange::Subtract(const ZoneList<CharacterRange>* src,
const ZoneList<CharacterRange>* to_remove,
ZoneList<CharacterRange>* result, Zone* zone) {
DCHECK(CharacterRange::IsCanonical(src));
DCHECK(CharacterRange::IsCanonical(to_remove));
DCHECK_EQ(0, result->length());
if (src->is_empty()) return;
int src_index = 0;
int to_remove_index = 0;
base::uc32 from = src->at(src_index).from();
base::uc32 to = src->at(src_index).to();
while (src_index < src->length() && to_remove_index < to_remove->length()) {
CharacterRange remove_range = to_remove->at(to_remove_index);
if (remove_range.to() < from) {
// (a) Non-overlapping case, ignore current to_remove range.
// |-------|
// |-------|
to_remove_index++;
} else if (to < remove_range.from()) {
// (b) Non-overlapping case, add full current range to result.
// |-------|
// |-------|
result->Add(CharacterRange::Range(from, to), zone);
SafeAdvanceRange(src, &src_index, &from, &to);
} else if (from >= remove_range.from() && to <= remove_range.to()) {
// (c) Current to_remove range fully covers current range.
// |---|
// |-------|
SafeAdvanceRange(src, &src_index, &from, &to);
} else if (from < remove_range.from() && to > remove_range.to()) {
// (d) Split current range.
// |-------|
// |---|
result->Add(CharacterRange::Range(from, remove_range.from() - 1), zone);
from = remove_range.to() + 1;
to_remove_index++;
} else if (from < remove_range.from()) {
// (e) End current range.
// |-------|
// |-------|
to = remove_range.from() - 1;
result->Add(CharacterRange::Range(from, to), zone);
SafeAdvanceRange(src, &src_index, &from, &to);
} else if (to > remove_range.to()) {
// (f) Modify start of current range.
// |-------|
// |-------|
from = remove_range.to() + 1;
to_remove_index++;
} else {
UNREACHABLE();
}
}
// The last range needs special treatment after |to_remove| is exhausted, as
// |from| might have been modified by the last |to_remove| range and |to| was
// not yet known (i.e. cases d and f).
if (from <= to) {
result->Add(CharacterRange::Range(from, to), zone);
}
src_index++;
// Add remaining ranges after |to_remove| is exhausted.
for (; src_index < src->length(); src_index++) {
result->Add(src->at(src_index), zone);
}
DCHECK(IsCanonical(result));
}
// static
void CharacterRange::ClampToOneByte(ZoneList<CharacterRange>* ranges) {
DCHECK(IsCanonical(ranges));
// Drop all ranges that don't contain one-byte code units, and clamp the last
// range s.t. it likewise only contains one-byte code units. Note this relies
// on `ranges` being canonicalized, i.e. sorted and non-overlapping.
static constexpr base::uc32 max_char = String::kMaxOneByteCharCodeU;
int n = ranges->length();
for (; n > 0; n--) {
CharacterRange& r = ranges->at(n - 1);
if (r.from() <= max_char) {
r.to_ = std::min(r.to_, max_char);
break;
}
}
ranges->Rewind(n);
}
// static
bool CharacterRange::Equals(const ZoneList<CharacterRange>* lhs,
const ZoneList<CharacterRange>* rhs) {
DCHECK(IsCanonical(lhs));
DCHECK(IsCanonical(rhs));
if (lhs->length() != rhs->length()) return false;
for (int i = 0; i < lhs->length(); i++) {
if (lhs->at(i) != rhs->at(i)) return false;
}
return true;
}
namespace {
// Scoped object to keep track of how much we unroll quantifier loops in the
// regexp graph generator.
class RegExpExpansionLimiter {
public:
static const int kMaxExpansionFactor = 6;
RegExpExpansionLimiter(RegExpCompiler* compiler, int factor)
: compiler_(compiler),
saved_expansion_factor_(compiler->current_expansion_factor()),
ok_to_expand_(saved_expansion_factor_ <= kMaxExpansionFactor) {
DCHECK_LT(0, factor);
if (ok_to_expand_) {
if (factor > kMaxExpansionFactor) {
// Avoid integer overflow of the current expansion factor.
ok_to_expand_ = false;
compiler->set_current_expansion_factor(kMaxExpansionFactor + 1);
} else {
int new_factor = saved_expansion_factor_ * factor;
ok_to_expand_ = (new_factor <= kMaxExpansionFactor);
compiler->set_current_expansion_factor(new_factor);
}
}
}
~RegExpExpansionLimiter() {
compiler_->set_current_expansion_factor(saved_expansion_factor_);
}
bool ok_to_expand() { return ok_to_expand_; }
private:
RegExpCompiler* compiler_;
int saved_expansion_factor_;
bool ok_to_expand_;
DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpExpansionLimiter);
};
} // namespace
RegExpNode* RegExpQuantifier::ToNode(int min, int max, bool is_greedy,
RegExpTree* body, RegExpCompiler* compiler,
RegExpNode* on_success,
bool not_at_start) {
// x{f, t} becomes this:
//
// (r++)<-.
// | `
// | (x)
// v ^
// (r=0)-->(?)---/ [if r < t]
// |
// [if r >= f] \----> ...
//
// 15.10.2.5 RepeatMatcher algorithm.
// The parser has already eliminated the case where max is 0. In the case
// where max_match is zero the parser has removed the quantifier if min was
// > 0 and removed the atom if min was 0. See AddQuantifierToAtom.
// If we know that we cannot match zero length then things are a little
// simpler since we don't need to make the special zero length match check
// from step 2.1. If the min and max are small we can unroll a little in
// this case.
static const int kMaxUnrolledMinMatches = 3; // Unroll (foo)+ and (foo){3,}
static const int kMaxUnrolledMaxMatches = 3; // Unroll (foo)? and (foo){x,3}
if (max == 0) return on_success; // This can happen due to recursion.
bool body_can_be_empty = (body->min_match() == 0);
int body_start_reg = RegExpCompiler::kNoRegister;
Interval capture_registers = body->CaptureRegisters();
bool needs_capture_clearing = !capture_registers.is_empty();
Zone* zone = compiler->zone();
if (body_can_be_empty) {
body_start_reg = compiler->AllocateRegister();
} else if (compiler->optimize() && !needs_capture_clearing) {
// Only unroll if there are no captures and the body can't be
// empty.
{
RegExpExpansionLimiter limiter(compiler, min + ((max != min) ? 1 : 0));
if (min > 0 && min <= kMaxUnrolledMinMatches && limiter.ok_to_expand()) {
int new_max = (max == kInfinity) ? max : max - min;
// Recurse once to get the loop or optional matches after the fixed
// ones.
RegExpNode* answer =
ToNode(0, new_max, is_greedy, body, compiler, on_success, true);
// Unroll the forced matches from 0 to min. This can cause chains of
// TextNodes (which the parser does not generate). These should be
// combined if it turns out they hinder good code generation.
for (int i = 0; i < min; i++) {
answer = body->ToNode(compiler, answer);
}
return answer;
}
}
if (max <= kMaxUnrolledMaxMatches && min == 0) {
DCHECK_LT(0, max); // Due to the 'if' above.
RegExpExpansionLimiter limiter(compiler, max);
if (limiter.ok_to_expand()) {
// Unroll the optional matches up to max.
RegExpNode* answer = on_success;
for (int i = 0; i < max; i++) {
ChoiceNode* alternation = zone->New<ChoiceNode>(2, zone);
if (is_greedy) {
alternation->AddAlternative(
GuardedAlternative(body->ToNode(compiler, answer)));
alternation->AddAlternative(GuardedAlternative(on_success));
} else {
alternation->AddAlternative(GuardedAlternative(on_success));
alternation->AddAlternative(
GuardedAlternative(body->ToNode(compiler, answer)));
}
answer = alternation;
if (not_at_start && !compiler->read_backward()) {
alternation->set_not_at_start();
}
}
return answer;
}
}
}
bool has_min = min > 0;
bool has_max = max < RegExpTree::kInfinity;
bool needs_counter = has_min || has_max;
int reg_ctr = needs_counter ? compiler->AllocateRegister()
: RegExpCompiler::kNoRegister;
LoopChoiceNode* center = zone->New<LoopChoiceNode>(
body->min_match() == 0, compiler->read_backward(), min, zone);
if (not_at_start && !compiler->read_backward()) center->set_not_at_start();
RegExpNode* loop_return =
needs_counter ? static_cast<RegExpNode*>(
ActionNode::IncrementRegister(reg_ctr, center))
: static_cast<RegExpNode*>(center);
if (body_can_be_empty) {
// If the body can be empty we need to check if it was and then
// backtrack.
loop_return =
ActionNode::EmptyMatchCheck(body_start_reg, reg_ctr, min, loop_return);
}
RegExpNode* body_node = body->ToNode(compiler, loop_return);
if (body_can_be_empty) {
// If the body can be empty we need to store the start position
// so we can bail out if it was empty.
body_node = ActionNode::StorePosition(body_start_reg, false, body_node);
}
if (needs_capture_clearing) {
// Before entering the body of this loop we need to clear captures.
body_node = ActionNode::ClearCaptures(capture_registers, body_node);
}
GuardedAlternative body_alt(body_node);
if (has_max) {
Guard* body_guard = zone->New<Guard>(reg_ctr, Guard::LT, max);
body_alt.AddGuard(body_guard, zone);
}
GuardedAlternative rest_alt(on_success);
if (has_min) {
Guard* rest_guard = compiler->zone()->New<Guard>(reg_ctr, Guard::GEQ, min);
rest_alt.AddGuard(rest_guard, zone);
}
if (is_greedy) {
center->AddLoopAlternative(body_alt);
center->AddContinueAlternative(rest_alt);
} else {
center->AddContinueAlternative(rest_alt);
center->AddLoopAlternative(body_alt);
}
if (needs_counter) {
return ActionNode::SetRegisterForLoop(reg_ctr, 0, center);
} else {
return center;
}
}
} // namespace internal
} // namespace v8