michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef vm_MatchPairs_h
michael@0: #define vm_MatchPairs_h
michael@0: 
michael@0: #include "jsalloc.h"
michael@0: 
michael@0: #include "ds/LifoAlloc.h"
michael@0: #include "js/Vector.h"
michael@0: 
michael@0: /*
michael@0:  * RegExp match results are succinctly represented by pairs of integer
michael@0:  * indices delimiting (start, limit] segments of the input string.
michael@0:  *
michael@0:  * The pair count for a given RegExp match is the capturing parentheses
michael@0:  * count plus one for the "0 capturing paren" whole text match.
michael@0:  */
michael@0: 
michael@0: namespace js {
michael@0: 
michael@0: struct MatchPair
michael@0: {
michael@0:     int start;
michael@0:     int limit;
michael@0: 
michael@0:     MatchPair()
michael@0:       : start(-1), limit(-1)
michael@0:     { }
michael@0: 
michael@0:     MatchPair(int start, int limit)
michael@0:       : start(start), limit(limit)
michael@0:     { }
michael@0: 
michael@0:     size_t length()      const { JS_ASSERT(!isUndefined()); return limit - start; }
michael@0:     bool isEmpty()       const { return length() == 0; }
michael@0:     bool isUndefined()   const { return start < 0; }
michael@0: 
michael@0:     void displace(size_t amount) {
michael@0:         start += (start < 0) ? 0 : amount;
michael@0:         limit += (limit < 0) ? 0 : amount;
michael@0:     }
michael@0: 
michael@0:     inline bool check() const {
michael@0:         JS_ASSERT(limit >= start);
michael@0:         JS_ASSERT_IF(start < 0, start == -1);
michael@0:         JS_ASSERT_IF(limit < 0, limit == -1);
michael@0:         return true;
michael@0:     }
michael@0: };
michael@0: 
michael@0: /* Base class for RegExp execution output. */
michael@0: class MatchPairs
michael@0: {
michael@0:   protected:
michael@0:     size_t     pairCount_;   /* Length of pairs_. */
michael@0:     MatchPair *pairs_;       /* Raw pointer into an allocated MatchPair buffer. */
michael@0: 
michael@0:   protected:
michael@0:     /* Not used directly: use ScopedMatchPairs or VectorMatchPairs. */
michael@0:     MatchPairs()
michael@0:       : pairCount_(0), pairs_(nullptr)
michael@0:     { }
michael@0: 
michael@0:   protected:
michael@0:     /* Functions used by friend classes. */
michael@0:     friend class RegExpShared;
michael@0:     friend class RegExpStatics;
michael@0: 
michael@0:     /* MatchPair buffer allocator: set pairs_ and pairCount_. */
michael@0:     virtual bool allocOrExpandArray(size_t pairCount) = 0;
michael@0: 
michael@0:     bool initArray(size_t pairCount);
michael@0:     bool initArrayFrom(MatchPairs &copyFrom);
michael@0:     void forgetArray() { pairs_ = nullptr; }
michael@0: 
michael@0:     void displace(size_t disp);
michael@0:     void checkAgainst(size_t inputLength) {
michael@0: #ifdef DEBUG
michael@0:         for (size_t i = 0; i < pairCount_; i++) {
michael@0:             const MatchPair &p = pair(i);
michael@0:             JS_ASSERT(p.check());
michael@0:             if (p.isUndefined())
michael@0:                 continue;
michael@0:             JS_ASSERT(size_t(p.limit) <= inputLength);
michael@0:         }
michael@0: #endif
michael@0:     }
michael@0: 
michael@0:   public:
michael@0:     /* Querying functions in the style of RegExpStatics. */
michael@0:     bool   empty() const           { return pairCount_ == 0; }
michael@0:     size_t pairCount() const       { JS_ASSERT(pairCount_ > 0); return pairCount_; }
michael@0:     size_t parenCount() const      { return pairCount_ - 1; }
michael@0: 
michael@0:   public:
michael@0:     unsigned *rawBuf() const { return reinterpret_cast<unsigned *>(pairs_); }
michael@0:     size_t length() const { return pairCount_; }
michael@0: 
michael@0:     /* Pair accessors. */
michael@0:     const MatchPair &pair(size_t i) const {
michael@0:         JS_ASSERT(pairCount_ && i < pairCount_);
michael@0:         JS_ASSERT(pairs_);
michael@0:         return pairs_[i];
michael@0:     }
michael@0: 
michael@0:     const MatchPair &operator[](size_t i) const { return pair(i); }
michael@0: };
michael@0: 
michael@0: /* MatchPairs allocated into temporary storage, removed when out of scope. */
michael@0: class ScopedMatchPairs : public MatchPairs
michael@0: {
michael@0:     LifoAllocScope lifoScope_;
michael@0: 
michael@0:   public:
michael@0:     /* Constructs an implicit LifoAllocScope. */
michael@0:     ScopedMatchPairs(LifoAlloc *lifoAlloc)
michael@0:       : lifoScope_(lifoAlloc)
michael@0:     { }
michael@0: 
michael@0:     const MatchPair &operator[](size_t i) const { return pair(i); }
michael@0: 
michael@0:   protected:
michael@0:     bool allocOrExpandArray(size_t pairCount);
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * MatchPairs allocated into permanent storage, for RegExpStatics.
michael@0:  * The Vector of MatchPairs is reusable by Vector expansion.
michael@0:  */
michael@0: class VectorMatchPairs : public MatchPairs
michael@0: {
michael@0:     Vector<MatchPair, 10, SystemAllocPolicy> vec_;
michael@0: 
michael@0:   public:
michael@0:     VectorMatchPairs() {
michael@0:         vec_.clear();
michael@0:     }
michael@0: 
michael@0:     const MatchPair &operator[](size_t i) const { return pair(i); }
michael@0: 
michael@0:   protected:
michael@0:     friend class RegExpStatics;
michael@0:     bool allocOrExpandArray(size_t pairCount);
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * Passes either MatchPair or MatchPairs through ExecuteRegExp()
michael@0:  * to avoid duplication of generic code.
michael@0:  */
michael@0: struct MatchConduit
michael@0: {
michael@0:     union {
michael@0:         MatchPair  *pair;
michael@0:         MatchPairs *pairs;
michael@0:     } u;
michael@0:     bool isPair;
michael@0: 
michael@0:     explicit MatchConduit(MatchPair *pair) {
michael@0:         isPair = true;
michael@0:         u.pair = pair;
michael@0:     }
michael@0:     explicit MatchConduit(MatchPairs *pairs) {
michael@0:         isPair = false;
michael@0:         u.pairs = pairs;
michael@0:     }
michael@0: };
michael@0: 
michael@0: } /* namespace js */
michael@0: 
michael@0: #endif /* vm_MatchPairs_h */