/** * \file Compare.cpp * This file is part of LyX, the document processor. * Licence details can be found in the file COPYING. * * \author Vincent van Ravesteijn * * Full author contact details are available in file CREDITS. */ #include #include "Compare.h" #include "Author.h" #include "Buffer.h" #include "BufferParams.h" #include "Changes.h" #include "CutAndPaste.h" #include "ErrorList.h" #include "Font.h" #include "insets/InsetText.h" #include "support/docstream.h" #include "support/lassert.h" #include "support/qstring_helpers.h" using namespace std; using namespace lyx::support; namespace lyx { enum Direction { Forward = 0, Backward }; static void step(DocIterator & dit, Direction direction) { if (direction == Forward) dit.top().forwardPos(); else dit.top().backwardPos(); } static void step(DocIterator & dit, DocIterator const & end, Direction direction) { if (dit != end) step(dit, direction); } /** * A pair of two DocIterators that form a range. */ class DocRange { public: DocRange(DocIterator const & from_, DocIterator const & to_) : from(from_), to(to_) {} DocRange(Buffer const * buf) : from(doc_iterator_begin(buf)), to(doc_iterator_end(buf)) { to.backwardPos(); } /// Text * text() const { return from.text(); } /// bool empty() const { return to <= from; } /// size_t length() const; /// The begin of the range DocIterator from; /// The end of the range DocIterator to; }; size_t DocRange::length() const { ParagraphList const & ps = from.text()->paragraphs(); size_t length = 0; pit_type pit = from.pit(); pit_type const endpit = to.pit(); for (; pit < endpit; ++pit) length += ps[pit].size() + 1; length += to.pos() - from.pos(); return length; } class DocPair { public: DocPair() {} DocPair(DocIterator const & o_, DocIterator const & n_) : o(o_), n(n_) {} bool operator!=(DocPair const & rhs) const { // this might not be intuitive but correct for our purpose return o != rhs.o && n != rhs.n; } DocPair & operator++() { step(o, Forward); step(n, Forward); return *this; } DocPair & operator--() { step(o, Backward); step(n, Backward); return *this; } /// DocIterator o; /// DocIterator n; }; /** * A pair of two DocRanges. */ class DocRangePair { public: DocRangePair(DocRange const & o_, DocRange const & n_) : o(o_), n(n_) {} DocRangePair(DocPair const & from, DocPair const & to) : o(from.o, to.o), n(from.n, to.n) {} DocRangePair(Buffer const * o_buf, Buffer const * n_buf) : o(o_buf), n(n_buf) {} /// Returns the from pair DocPair from() const { return DocPair(o.from, n.from); } /// Returns the to pair DocPair to() const { return DocPair(o.to, n.to); } DocRange o; DocRange n; }; static DocRangePair stepIntoInset(DocPair const & inset_location) { DocRangePair rp(inset_location, inset_location); rp.o.from.forwardPos(); rp.n.from.forwardPos(); step(rp.o.to, Forward); step(rp.n.to, Forward); rp.o.to.backwardPos(); rp.n.to.backwardPos(); return rp; } /** * This class is designed to hold a vector that has both positive as * negative indices. It is internally represented as two vectors, one * for non-zero indices and one for negative indices. In this way, the * vector can grow in both directions. * If an index is not available in the vector, the default value is * returned. If an object is put in the vector beyond its size, the * empty spots in between are also filled with the default value. */ template class compl_vector { public: compl_vector() {} void reset(T const & def) { default_ = def; Vp_.clear(); Vn_.clear(); } /// Gets the value at index. If it is not in the vector /// the default value is inserted and returned. T & operator[](int index) { vector & V = index >= 0 ? Vp_ : Vn_; unsigned int const ii = index >= 0 ? index : -index - 1; while (ii >= V.size()) V.push_back(default_); return V[ii]; } private: /// The vector for positive indices vector Vp_; /// The vector for negative indices vector Vn_; /// The default value that is inserted in the vector /// if more space is needed T default_; }; /** * The implementation of the algorithm that does the comparison * between two documents. */ class Compare::Impl { public: /// Impl(Compare const & compare) : abort_(false), n_(0), m_(0), offset_reverse_diagonal_(0), odd_offset_(false), compare_(compare), old_buf_(nullptr), new_buf_(nullptr), dest_buf_(nullptr), dest_pars_(nullptr), recursion_level_(0), nested_inset_level_(0), D_(0) {} /// ~Impl() {} // Algorithm to find the shortest edit string. This algorithm // only needs a linear amount of memory (linear with the sum // of the number of characters in the two paragraph-lists). bool diff(Buffer const * new_buf, Buffer const * old_buf, Buffer const * dest_buf); /// Set to true to cancel the algorithm bool abort_; /// QString status() { QString status; status += toqstr("recursion level:") + " " + QString::number(recursion_level_) + " " + toqstr("differences:") + " " + QString::number(D_); return status; } private: /// Finds the middle snake and returns the length of the /// shortest edit script. int findMiddleSnake(DocRangePair const & rp, DocPair & middle_snake); enum SnakeResult { NoSnake, SingleSnake, NormalSnake }; /// Retrieve the middle snake when there is overlap between /// the forward and backward path. SnakeResult retrieveMiddleSnake(int k, int D, Direction direction, DocPair & middle_snake); /// Find the furthest reaching D-path (number of horizontal /// and vertical steps; differences between the old and new /// document) in the k-diagonal (vertical minus horizontal steps). void furthestDpathKdiagonal(int D, int k, DocRangePair const & rp, Direction direction); /// Is there overlap between the forward and backward path bool overlap(int k, int D); /// This function is called recursively by a divide and conquer /// algorithm. Each time, the string is divided into two split /// around the middle snake. void diff_i(DocRangePair const & rp); /// Processes the split chunks. It either adds them as deleted, /// as added, or call diff_i for further processing. void diffPart(DocRangePair const & rp); /// Runs the algorithm for the inset located at /c it and /c it_n /// and adds the result to /c pars. void diffInset(Inset * inset, DocPair const & p); /// Adds the snake to the destination buffer. The algorithm will /// recursively be applied to any InsetTexts that are within the snake. void processSnake(DocRangePair const & rp); /// Writes the range to the destination buffer void writeToDestBuffer(DocRange const & range, Change::Type type = Change::UNCHANGED); /// Writes the paragraph list to the destination buffer void writeToDestBuffer(ParagraphList const & copy_pars) const; /// The length of the old chunk currently processed int n_; /// The length of the new chunk currently processed int m_; /// The offset diagonal of the reverse path of the /// currently processed chunk int offset_reverse_diagonal_; /// Is the offset odd or even ? bool odd_offset_; /// The thread object, used to emit signals to the GUI Compare const & compare_; /// The buffer containing text that will be marked as old Buffer const * old_buf_; /// The buffer containing text that will be marked as new Buffer const * new_buf_; /// The buffer containing text that will be marked as new Buffer const * dest_buf_; /// The paragraph list of the destination buffer ParagraphList * dest_pars_; /// The level of recursion int recursion_level_; /// The number of nested insets at this level int nested_inset_level_; /// The position/snake in the old/new document /// of the forward/reverse search compl_vector ofp; compl_vector nfp; compl_vector ofs; compl_vector nfs; compl_vector orp; compl_vector nrp; compl_vector ors; compl_vector nrs; /// The number of differences in the path the algorithm /// is currently processing. int D_; }; ///////////////////////////////////////////////////////////////////// // // Compare // ///////////////////////////////////////////////////////////////////// Compare::Compare(Buffer const * new_buf, Buffer const * old_buf, Buffer * const dest_buf, CompareOptions const & options) : new_buffer(new_buf), old_buffer(old_buf), dest_buffer(dest_buf), options_(options), pimpl_(new Impl(*this)) { connect(&status_timer_, SIGNAL(timeout()), this, SLOT(doStatusMessage())); status_timer_.start(1000); } void Compare::doStatusMessage() { statusMessage(pimpl_->status()); } void Compare::run() { if (!dest_buffer || !new_buffer || !old_buffer) return; // Copy the buffer params to the destination buffer dest_buffer->params() = options_.settings_from_new ? new_buffer->params() : old_buffer->params(); // Copy extra authors to the destination buffer AuthorList const & extra_authors = options_.settings_from_new ? old_buffer->params().authors() : new_buffer->params().authors(); AuthorList::Authors::const_iterator it = extra_authors.begin(); for (; it != extra_authors.end(); ++it) dest_buffer->params().authors().record(*it); // We will need this later DocumentClassConstPtr const olddc = dest_buffer->params().documentClassPtr(); // We do not want to share the DocumentClass with the other Buffer. // See bug #10295. dest_buffer->params().makeDocumentClass(dest_buffer->isClone(), dest_buffer->isInternal()); doStatusMessage(); // Do the real work if (!doCompare()) return; // The comparison routine simply copies the paragraphs over into the // new buffer with the document class from wherever they came from. // So we need to reset the document class of all the paragraphs. // See bug #10295. cap::switchBetweenClasses( olddc, dest_buffer->params().documentClassPtr(), static_cast(dest_buffer->inset())); finished(pimpl_->abort_); } int Compare::doCompare() { return pimpl_->diff(new_buffer, old_buffer, dest_buffer); } void Compare::abort() { pimpl_->abort_ = true; condition_.wakeOne(); wait(); pimpl_->abort_ = false; } static void getParagraphList(DocRange const & range, ParagraphList & pars) { // Clone the paragraphs within the selection. pit_type startpit = range.from.pit(); pit_type endpit = range.to.pit(); ParagraphList const & ps_ = range.text()->paragraphs(); ParagraphList tmp_pars(ps_.iterator_at(startpit), ps_.iterator_at(endpit + 1)); // Remove the end of the last paragraph; afterwards, remove the // beginning of the first paragraph. Keep this order - there may only // be one paragraph! Paragraph & back = tmp_pars.back(); back.eraseChars(range.to.pos(), back.size(), false); Paragraph & front = tmp_pars.front(); front.eraseChars(0, range.from.pos(), false); pars.insert(pars.begin(), tmp_pars.begin(), tmp_pars.end()); } static bool equal(Inset const * i_o, Inset const * i_n) { if (!i_o || !i_n) return false; // Different types of insets if (i_o->lyxCode() != i_n->lyxCode()) return false; // Editable insets are assumed to be the same as they are of the // same type. If we later on decide that we insert them in the // document as being unchanged, we will run the algorithm on the // contents of the two insets. // FIXME: This fails if the parameters of the insets differ. // FIXME: We do not recurse into InsetTabulars. // FIXME: We need methods inset->equivalent(inset). if (i_o->editable() && !i_o->asInsetMath() && i_o->asInsetText()) return true; ostringstream o_os; ostringstream n_os; i_o->write(o_os); i_n->write(n_os); return o_os.str() == n_os.str(); } static bool equal(DocIterator & o, DocIterator & n) { // Explicitly check for this, so we won't call // Paragraph::getChar for the last pos. bool const o_lastpos = o.pos() == o.lastpos(); bool const n_lastpos = n.pos() == n.lastpos(); if (o_lastpos || n_lastpos) return o_lastpos && n_lastpos; Paragraph const & old_par = o.text()->getPar(o.pit()); Paragraph const & new_par = n.text()->getPar(n.pit()); char_type const c_o = old_par.getChar(o.pos()); char_type const c_n = new_par.getChar(n.pos()); if (c_o != c_n) return false; if (old_par.isInset(o.pos())) { Inset const * i_o = old_par.getInset(o.pos()); Inset const * i_n = new_par.getInset(n.pos()); if (i_o && i_n) return equal(i_o, i_n); } Font fo = old_par.getFontSettings(o.buffer()->params(), o.pos()); Font fn = new_par.getFontSettings(n.buffer()->params(), n.pos()); return fo == fn; } /// Traverses a snake in a certain direction. p points to a /// position in the old and new file and they are synchronously /// moved along the snake. The function returns true if a snake /// was found. static bool traverseSnake(DocPair & p, DocRangePair const & range, Direction direction) { bool ret = false; DocPair const & p_end = direction == Forward ? range.to() : range.from(); while (p != p_end) { if (direction == Backward) --p; if (!equal(p.o, p.n)) { if (direction == Backward) ++p; return ret; } if (direction == Forward) ++p; ret = true; } return ret; } ///////////////////////////////////////////////////////////////////// // // Compare::Impl // ///////////////////////////////////////////////////////////////////// void Compare::Impl::furthestDpathKdiagonal(int D, int k, DocRangePair const & rp, Direction direction) { compl_vector & op = direction == Forward ? ofp : orp; compl_vector & np = direction == Forward ? nfp : nrp; compl_vector & os = direction == Forward ? ofs : ors; compl_vector & ns = direction == Forward ? nfs : nrs; // A vertical step means stepping one character in the new document. bool vertical_step = k == -D; if (!vertical_step && k != D) { vertical_step = direction == Forward ? op[k - 1] < op[k + 1] : op[k - 1] > op[k + 1]; } // Where do we take the step from ? int const kk = vertical_step ? k + 1 : k - 1; DocPair p(op[kk], np[kk]); DocPair const s(os[kk], ns[kk]); // If D==0 we simulate a vertical step from (0,-1) by doing nothing. if (D != 0) { // Take a step if (vertical_step && direction == Forward) step(p.n, rp.n.to, direction); else if (vertical_step && direction == Backward) step(p.n, rp.n.from, direction); else if (!vertical_step && direction == Forward) step(p.o, rp.o.to, direction); else if (!vertical_step && direction == Backward) step(p.o, rp.o.from, direction); } // Traverse snake if (traverseSnake(p, rp, direction)) { // Record last snake os[k] = p.o; ns[k] = p.n; } else { // Copy last snake from the previous step os[k] = s.o; ns[k] = s.n; } //Record new position op[k] = p.o; np[k] = p.n; } bool Compare::Impl::overlap(int k, int D) { // To generalize for the forward and reverse checks int kk = offset_reverse_diagonal_ - k; // Can we have overlap ? if (kk <= D && kk >= -D) { // Do we have overlap ? if (odd_offset_) return ofp[k] >= orp[kk] && nfp[k] >= nrp[kk]; else return ofp[kk] >= orp[k] && nfp[kk] >= nrp[k]; } return false; } Compare::Impl::SnakeResult Compare::Impl::retrieveMiddleSnake( int k, int D, Direction direction, DocPair & middle_snake) { compl_vector & os = direction == Forward ? ofs : ors; compl_vector & ns = direction == Forward ? nfs : nrs; compl_vector & os_r = direction == Forward ? ors : ofs; compl_vector & ns_r = direction == Forward ? nrs : nfs; // The diagonal while doing the backward search int kk = -k + offset_reverse_diagonal_; // Did we find a snake ? if (os[k].empty() && os_r[kk].empty()) { // No, there is no snake at all, in which case // the length of the shortest edit script is M+N. LATTEST(2 * D - odd_offset_ == m_ + n_); return NoSnake; } if (os[k].empty()) { // Yes, but there is only 1 snake and we found it in the // reverse path. middle_snake.o = os_r[kk]; middle_snake.n = ns_r[kk]; return SingleSnake; } middle_snake.o = os[k]; middle_snake.n = ns[k]; return NormalSnake; } int Compare::Impl::findMiddleSnake(DocRangePair const & rp, DocPair & middle_snake) { // The lengths of the old and new chunks. n_ = rp.o.length(); m_ = rp.n.length(); // Forward paths are centered around the 0-diagonal; reverse paths // are centered around the diagonal N - M. (Delta in the article) offset_reverse_diagonal_ = n_ - m_; // If the offset is odd, only check for overlap while extending forward // paths, otherwise only check while extending reverse paths. odd_offset_ = (offset_reverse_diagonal_ % 2 != 0); ofp.reset(rp.o.from); nfp.reset(rp.n.from); ofs.reset(DocIterator()); nfs.reset(DocIterator()); orp.reset(rp.o.to); nrp.reset(rp.n.to); ors.reset(DocIterator()); nrs.reset(DocIterator()); // In the formula below, the "+ 1" ensures we round like ceil() int const D_max = (m_ + n_ + 1)/2; // D is the number of horizontal and vertical steps, i.e. // different characters in the old and new chunk. for (int D = 0; D <= D_max; ++D) { // to be used in the status messages D_ = D; // Forward and reverse paths for (int f = 0; f < 2; ++f) { Direction direction = f == 0 ? Forward : Backward; // Diagonals between -D and D can be reached by a D-path for (int k = -D; k <= D; k += 2) { // Find the furthest reaching D-path on this diagonal furthestDpathKdiagonal(D, k, rp, direction); // Only check for overlap for forward paths if the offset is odd // and only for reverse paths if the offset is even. if (odd_offset_ == (direction == Forward)) { // Do the forward and backward paths overlap ? if (overlap(k, D - odd_offset_)) { retrieveMiddleSnake(k, D, direction, middle_snake); return 2 * D - odd_offset_; } } if (abort_) return 0; } } } // This should never be reached return -2; } bool Compare::Impl::diff(Buffer const * new_buf, Buffer const * old_buf, Buffer const * dest_buf) { if (!new_buf || !old_buf || !dest_buf) return false; old_buf_ = old_buf; new_buf_ = new_buf; dest_buf_ = dest_buf; dest_pars_ = &dest_buf->inset().asInsetText()->paragraphs(); dest_pars_->clear(); recursion_level_ = 0; nested_inset_level_ = 0; DocRangePair rp(old_buf_, new_buf_); DocPair from = rp.from(); traverseSnake(from, rp, Forward); DocRangePair const snake(rp.from(), from); processSnake(snake); // Start the recursive algorithm DocRangePair rp_new(from, rp.to()); if (!rp_new.o.empty() || !rp_new.n.empty()) diff_i(rp_new); for (pit_type p = 0; p < (pit_type)dest_pars_->size(); ++p) { (*dest_pars_)[p].setInsetBuffers(const_cast(*dest_buf)); (*dest_pars_)[p].setInsetOwner(&dest_buf_->inset()); } return true; } void Compare::Impl::diff_i(DocRangePair const & rp) { if (abort_) return; // The middle snake DocPair middle_snake; // Divides the problem into two smaller problems, split around // the snake in the middle. int const L_ses = findMiddleSnake(rp, middle_snake); // Set maximum of progress bar if (++recursion_level_ == 1) compare_.progressMax(L_ses); // There are now three possibilities: the strings were the same, // the strings were completely different, or we found a middle // snake and we can split the string into two parts to process. if (L_ses == 0) // Two the same strings (this must be a very rare case, because // usually this will be part of a snake adjacent to these strings). writeToDestBuffer(rp.o); else if (middle_snake.o.empty()) { // Two totally different strings writeToDestBuffer(rp.o, Change::DELETED); writeToDestBuffer(rp.n, Change::INSERTED); } else { // Retrieve the complete snake DocPair first_part_end = middle_snake; traverseSnake(first_part_end, rp, Backward); DocRangePair first_part(rp.from(), first_part_end); DocPair second_part_begin = middle_snake; traverseSnake(second_part_begin, rp, Forward); DocRangePair second_part(second_part_begin, rp.to()); // Split the string in three parts: // 1. in front of the snake diffPart(first_part); // 2. the snake itself, and DocRangePair const snake(first_part.to(), second_part.from()); processSnake(snake); // 3. behind the snake. diffPart(second_part); } --recursion_level_; } void Compare::Impl::diffPart(DocRangePair const & rp) { // Is there a finite length string in both buffers, if not there // is an empty string and we write the other one to the buffer. if (!rp.o.empty() && !rp.n.empty()) diff_i(rp); else if (!rp.o.empty()) writeToDestBuffer(rp.o, Change::DELETED); else if (!rp.n.empty()) writeToDestBuffer(rp.n, Change::INSERTED); } void Compare::Impl::diffInset(Inset * inset, DocPair const & p) { // Find the dociterators for the beginning and the // end of the inset, for the old and new document. DocRangePair const rp = stepIntoInset(p); // Recurse into the inset. Temporarily replace the dest_pars // paragraph list by the paragraph list of the nested inset. ParagraphList * backup_dest_pars = dest_pars_; dest_pars_ = &inset->asInsetText()->text().paragraphs(); dest_pars_->clear(); ++nested_inset_level_; diff_i(rp); --nested_inset_level_; dest_pars_ = backup_dest_pars; } void Compare::Impl::processSnake(DocRangePair const & rp) { ParagraphList pars; getParagraphList(rp.o, pars); // Find insets in this paragaph list DocPair it = rp.from(); for (; it.o < rp.o.to; ++it) { Inset * inset = it.o.text()->getPar(it.o.pit()).getInset(it.o.pos()); if (inset && inset->editable() && inset->asInsetText()) { // Find the inset in the paragraph list that will be pasted into // the final document. The contents of the inset will be replaced // by the output of the algorithm below. pit_type const pit = it.o.pit() - rp.o.from.pit(); pos_type const pos = pit ? it.o.pos() : it.o.pos() - rp.o.from.pos(); inset = pars[pit].getInset(pos); LASSERT(inset, continue); diffInset(inset, it); } } writeToDestBuffer(pars); } void Compare::Impl::writeToDestBuffer(DocRange const & range, Change::Type type) { ParagraphList pars; getParagraphList(range, pars); pos_type size = 0; // Set the change ParagraphList::iterator it = pars.begin(); for (; it != pars.end(); ++it) { it->setChange(Change(type)); size += it->size(); } writeToDestBuffer(pars); if (nested_inset_level_ == 0) compare_.progress(size); } void Compare::Impl::writeToDestBuffer(ParagraphList const & pars) const { pit_type const pit = dest_pars_->size() - 1; dest_pars_->insert(dest_pars_->end(), pars.begin(), pars.end()); if (pit >= 0) mergeParagraph(dest_buf_->params(), *dest_pars_, pit); } #include "moc_Compare.cpp" } // namespace lyx