#include <boost/next_prior.hpp>
+#include <cmath>
+
using namespace std;
using namespace lyx::support;
size_t DocRange::length() const
{
- pit_type startpit = from.pit();
- pit_type endpit = to.pit();
- ParagraphList const & ps_ = from.text()->paragraphs();
-
- ParagraphList pars(boost::next(ps_.begin(), startpit),
- boost::next(ps_.begin(), endpit + 1));
-
- // Remove the end of the last paragraph; afterwards, remove the
- // beginning of the first paragraph.
- Paragraph & back = pars.back();
- back.eraseChars(to.pos(), back.size(), false);
- Paragraph & front = pars.front();
- front.eraseChars(0, from.pos(), false);
-
- ParagraphList::const_iterator pit = pars.begin();
- ParagraphList::const_iterator end_it = pars.end();
-
+ ParagraphList const & ps = from.text()->paragraphs();
size_t length = 0;
- for (; pit != end_it; ++pit)
- length += pit->size() + 1;
-
- // The last paragraph has no paragraph-end
- --length;
- return length;
+ 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;
}
}
+/**
+ * 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 T>
+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<T> & 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<T> Vp_;
+ /// The vector for negative indices
+ vector<T> 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.
/// shortest edit script.
int find_middle_snake(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 retrieve_middle_snake(int k, int D, Direction direction,
+ DocPair & middle_snake);
+
+ /// Find the 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 furthest_Dpath_kdiagonal(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.
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 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<DocIterator> ofp;
+ compl_vector<DocIterator> nfp;
+ compl_vector<DocIterator> ofs;
+ compl_vector<DocIterator> nfs;
+ compl_vector<DocIterator> orp;
+ compl_vector<DocIterator> nrp;
+ compl_vector<DocIterator> ors;
+ compl_vector<DocIterator> nrs;
};
/////////////////////////////////////////////////////////////////////
//
/////////////////////////////////////////////////////////////////////
+
+void Compare::Impl::furthest_Dpath_kdiagonal(int D, int k,
+ DocRangePair const & rp, Direction direction)
+{
+ compl_vector<DocIterator> & op = direction == Forward ? ofp : orp;
+ compl_vector<DocIterator> & np = direction == Forward ? nfp : nrp;
+ compl_vector<DocIterator> & os = direction == Forward ? ofs : ors;
+ compl_vector<DocIterator> & 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]);
+
+ // 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 (traverse_snake(p, rp, direction)) {
+ // Record last snake
+ os[k] = p.o;
+ ns[k] = p.n;
+ } else {
+ // Copy last snake from the previous step
+ os[k] = os[kk];
+ ns[k] = ns[kk];
+ }
+
+ //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::retrieve_middle_snake(
+ int k, int D, Direction direction, DocPair & middle_snake)
+{
+ compl_vector<DocIterator> & os = direction == Forward ? ofs : ors;
+ compl_vector<DocIterator> & ns = direction == Forward ? nfs : nrs;
+ compl_vector<DocIterator> & os_r = direction == Forward ? ors : ofs;
+ compl_vector<DocIterator> & 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.
+ LASSERT(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::find_middle_snake(DocRangePair const & rp,
- DocPair &)
+ DocPair & middle_snake)
{
+ // The lengths of the old and new chunks.
N_ = rp.o.length();
M_ = rp.n.length();
- return M_ + N_;
+
+ // 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());
+
+ // D is the number of horizontal and vertical steps, i.e.
+ // different characters in the old and new chunk.
+ int const D_max = ceil(((double)M_ + N_)/2);
+ for (int D = 0; D <= D_max; ++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
+ furthest_Dpath_kdiagonal(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_)) {
+ retrieve_middle_snake(k, D, direction, middle_snake);
+ return 2 * D - odd_offset_;
+ }
+ }
+ }
+ }
+ }
+ // This should never be reached
+ return -2;
}
projects / lyx.git / blobdiff