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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef vm_MatchPairs_h
#define vm_MatchPairs_h
#include "jsalloc.h"
#include "ds/LifoAlloc.h"
#include "js/Vector.h"
/*
* RegExp match results are succinctly represented by pairs of integer
* indices delimiting (start, limit] segments of the input string.
*
* The pair count for a given RegExp match is the capturing parentheses
* count plus one for the "0 capturing paren" whole text match.
*/
namespace js {
struct MatchPair
{
int32_t start;
int32_t limit;
MatchPair()
: start(-1), limit(-1)
{ }
MatchPair(int32_t start, int32_t limit)
: start(start), limit(limit)
{ }
size_t length() const { MOZ_ASSERT(!isUndefined()); return limit - start; }
bool isEmpty() const { return length() == 0; }
bool isUndefined() const { return start < 0; }
void displace(size_t amount) {
start += (start < 0) ? 0 : amount;
limit += (limit < 0) ? 0 : amount;
}
inline bool check() const {
MOZ_ASSERT(limit >= start);
MOZ_ASSERT_IF(start < 0, start == -1);
MOZ_ASSERT_IF(limit < 0, limit == -1);
return true;
}
};
/* Base class for RegExp execution output. */
class MatchPairs
{
protected:
/* Length of pairs_. */
uint32_t pairCount_;
/* Raw pointer into an allocated MatchPair buffer. */
MatchPair* pairs_;
protected:
/* Not used directly: use ScopedMatchPairs or VectorMatchPairs. */
MatchPairs()
: pairCount_(0), pairs_(nullptr)
{ }
protected:
/* Functions used by friend classes. */
friend class RegExpShared;
friend class RegExpStatics;
/* MatchPair buffer allocator: set pairs_ and pairCount_. */
virtual bool allocOrExpandArray(size_t pairCount) = 0;
bool initArrayFrom(MatchPairs& copyFrom);
void forgetArray() { pairs_ = nullptr; }
void checkAgainst(size_t inputLength) {
#ifdef DEBUG
for (size_t i = 0; i < pairCount_; i++) {
const MatchPair& p = (*this)[i];
MOZ_ASSERT(p.check());
if (p.isUndefined())
continue;
MOZ_ASSERT(size_t(p.limit) <= inputLength);
}
#endif
}
public:
/* Querying functions in the style of RegExpStatics. */
bool empty() const { return pairCount_ == 0; }
size_t pairCount() const { MOZ_ASSERT(pairCount_ > 0); return pairCount_; }
size_t parenCount() const { return pairCount_ - 1; }
static size_t offsetOfPairs() { return offsetof(MatchPairs, pairs_); }
static size_t offsetOfPairCount() { return offsetof(MatchPairs, pairCount_); }
int32_t* pairsRaw() { return reinterpret_cast<int32_t*>(pairs_); }
public:
size_t length() const { return pairCount_; }
const MatchPair& operator[](size_t i) const {
MOZ_ASSERT(i < pairCount_);
return pairs_[i];
}
MatchPair& operator[](size_t i) {
MOZ_ASSERT(i < pairCount_);
return pairs_[i];
}
};
/* MatchPairs allocated into temporary storage, removed when out of scope. */
class ScopedMatchPairs : public MatchPairs
{
LifoAllocScope lifoScope_;
public:
/* Constructs an implicit LifoAllocScope. */
explicit ScopedMatchPairs(LifoAlloc* lifoAlloc)
: lifoScope_(lifoAlloc)
{ }
protected:
bool allocOrExpandArray(size_t pairCount);
};
/*
* MatchPairs allocated into permanent storage, for RegExpStatics.
* The Vector of MatchPairs is reusable by Vector expansion.
*/
class VectorMatchPairs : public MatchPairs
{
Vector<MatchPair, 10, SystemAllocPolicy> vec_;
public:
VectorMatchPairs() {
vec_.clear();
}
protected:
friend class RegExpStatics;
bool allocOrExpandArray(size_t pairCount);
};
} /* namespace js */
#endif /* vm_MatchPairs_h */
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