1 /**
2  * \file Compare.cpp
3  * This file is part of LyX, the document processor.
4  * Licence details can be found in the file COPYING.
5  *
6  * \author Vincent van Ravesteijn
7  *
8  * Full author contact details are available in file CREDITS.
9  */
10 
11 #include <config.h>
12 
13 #include "Compare.h"
14 
15 #include "Author.h"
16 #include "BufferParams.h"
17 #include "Changes.h"
18 #include "CutAndPaste.h"
19 #include "ErrorList.h"
20 #include "Font.h"
21 
22 #include "insets/InsetText.h"
23 
24 #include "support/docstream.h"
25 #include "support/lassert.h"
26 #include "support/lyxalgo.h"
27 #include "support/qstring_helpers.h"
28 
29 using namespace std;
30 using namespace lyx::support;
31 
32 
33 namespace lyx {
34 
35 
36 enum Direction {
37 	Forward = 0,
38 	Backward
39 };
40 
41 
step(DocIterator & dit,Direction direction)42 static void step(DocIterator & dit, Direction direction)
43 {
44 	if (direction == Forward)
45 		dit.top().forwardPos();
46 	else
47 		dit.top().backwardPos();
48 }
49 
50 
step(DocIterator & dit,DocIterator const & end,Direction direction)51 static void step(DocIterator & dit, DocIterator const & end, Direction direction)
52 {
53 	if (dit != end)
54 		step(dit, direction);
55 }
56 
57 
58 /**
59  * A pair of two DocIterators that form a range.
60  */
61 class DocRange {
62 public:
DocRange(DocIterator const & from_,DocIterator const & to_)63 	DocRange(DocIterator const & from_, DocIterator const & to_)
64 		: from(from_), to(to_)
65 	{}
66 
DocRange(Buffer const * buf)67 	DocRange(Buffer const * buf) :
68 		from(doc_iterator_begin(buf)),
69 		to(doc_iterator_end(buf))
70 	{
71 		to.backwardPos();
72 	}
73 
74 	///
text() const75 	Text * text() const { return from.text(); }
76 	///
empty() const77 	bool empty() const { return to <= from;	}
78 	///
79 	size_t length() const;
80 
81 	/// The begin of the range
82 	DocIterator from;
83 	/// The end of the range
84 	DocIterator to;
85 };
86 
87 
length() const88 size_t DocRange::length() const
89 {
90 	ParagraphList const & ps = from.text()->paragraphs();
91 	size_t length = 0;
92 	pit_type pit = from.pit();
93 	pit_type const endpit = to.pit();
94 	for (; pit < endpit; ++pit)
95 		length += ps[pit].size() + 1;
96 	length += to.pos() - from.pos();
97 	return length;
98 }
99 
100 
101 class DocPair {
102 public:
DocPair()103 	DocPair()
104 	{}
105 
DocPair(DocIterator o_,DocIterator n_)106 	DocPair(DocIterator o_, DocIterator n_)
107 		: o(o_), n(n_)
108 	{}
109 
operator !=(DocPair const & rhs)110 	bool operator!=(DocPair const & rhs)
111 	{
112 		// this might not be intuitive but correct for our purpose
113 		return o != rhs.o && n != rhs.n;
114 	}
115 
116 
operator ++()117 	DocPair & operator++()
118 	{
119 		step(o, Forward);
120 		step(n, Forward);
121 		return *this;
122 	}
123 
operator --()124 	DocPair & operator--()
125 	{
126 		step(o, Backward);
127 		step(n, Backward);
128 		return *this;
129 	}
130 	///
131 	DocIterator o;
132 	///
133 	DocIterator n;
134 };
135 
136 /**
137  * A pair of two DocRanges.
138  */
139 class DocRangePair {
140 public:
DocRangePair(DocRange const & o_,DocRange const & n_)141 	DocRangePair(DocRange const & o_, DocRange const & n_)
142 		: o(o_), n(n_)
143 	{}
144 
DocRangePair(DocPair const & from,DocPair const & to)145 	DocRangePair(DocPair const & from, DocPair const & to)
146 		: o(from.o, to.o), n(from.n, to.n)
147 	{}
148 
DocRangePair(Buffer const * o_buf,Buffer const * n_buf)149 	DocRangePair(Buffer const * o_buf, Buffer const * n_buf)
150 		: o(o_buf), n(n_buf)
151 	{}
152 
153 	/// Returns the from pair
from() const154 	DocPair from() const
155 	{
156 		return DocPair(o.from, n.from);
157 	}
158 
159 	/// Returns the to pair
to() const160 	DocPair to() const
161 	{
162 		return DocPair(o.to, n.to);
163 	}
164 
165 	DocRange o;
166 	DocRange n;
167 };
168 
169 
stepIntoInset(DocPair const & inset_location)170 static DocRangePair stepIntoInset(DocPair const & inset_location)
171 {
172 	DocRangePair rp(inset_location, inset_location);
173 	rp.o.from.forwardPos();
174 	rp.n.from.forwardPos();
175 	step(rp.o.to, Forward);
176 	step(rp.n.to, Forward);
177 	rp.o.to.backwardPos();
178 	rp.n.to.backwardPos();
179 	return rp;
180 }
181 
182 
183 /**
184  *  This class is designed to hold a vector that has both positive as
185  *  negative indices. It is internally represented as two vectors, one
186  *  for non-zero indices and one for negative indices. In this way, the
187  *  vector can grow in both directions.
188  *    If an index is not available in the vector, the default value is
189  *  returned. If an object is put in the vector beyond its size, the
190  *  empty spots in between are also filled with the default value.
191  */
192 template<class T>
193 class compl_vector {
194 public:
compl_vector()195 	compl_vector()
196 	{}
197 
reset(T const & def)198 	void reset(T const & def)
199 	{
200 		default_ = def;
201 		Vp_.clear();
202 		Vn_.clear();
203 	}
204 
205 	/// Gets the value at index. If it is not in the vector
206 	/// the default value is inserted and returned.
operator [](int index)207 	T & operator[](int index) {
208 		vector<T> & V = index >= 0 ? Vp_ : Vn_;
209 		unsigned int const ii = index >= 0 ? index : -index - 1;
210 		while (ii >= V.size())
211 			V.push_back(default_);
212 		return V[ii];
213 	}
214 
215 private:
216 	/// The vector for positive indices
217 	vector<T> Vp_;
218 	/// The vector for negative indices
219 	vector<T> Vn_;
220 	/// The default value that is inserted in the vector
221 	/// if more space is needed
222 	T default_;
223 };
224 
225 
226 /**
227  * The implementation of the algorithm that does the comparison
228  * between two documents.
229  */
230 class Compare::Impl {
231 public:
232 	///
Impl(Compare const & compare)233 	Impl(Compare const & compare)
234 		: abort_(false), n_(0), m_(0), offset_reverse_diagonal_(0),
235 		  odd_offset_(0), compare_(compare),
236 		  old_buf_(0), new_buf_(0), dest_buf_(0), dest_pars_(0),
237 		  recursion_level_(0), nested_inset_level_(0), D_(0)
238 	{}
239 
240 	///
~Impl()241 	~Impl()
242 	{}
243 
244 	// Algorithm to find the shortest edit string. This algorithm
245 	// only needs a linear amount of memory (linear with the sum
246 	// of the number of characters in the two paragraph-lists).
247 	bool diff(Buffer const * new_buf, Buffer const * old_buf,
248 		Buffer const * dest_buf);
249 
250 	/// Set to true to cancel the algorithm
251 	bool abort_;
252 
253 	///
status()254 	QString status()
255 	{
256 		QString status;
257 		status += toqstr("recursion level:") + " " + QString::number(recursion_level_)
258 			+ " " + toqstr("differences:") + " " + QString::number(D_);
259 		return status;
260 	}
261 
262 private:
263 	/// Finds the middle snake and returns the length of the
264 	/// shortest edit script.
265 	int findMiddleSnake(DocRangePair const & rp, DocPair & middle_snake);
266 
267 	enum SnakeResult {
268 		NoSnake,
269 		SingleSnake,
270 		NormalSnake
271 	};
272 
273 	/// Retrieve the middle snake when there is overlap between
274 	/// the forward and backward path.
275 	SnakeResult retrieveMiddleSnake(int k, int D, Direction direction,
276 		DocPair & middle_snake);
277 
278 	/// Find the furthest reaching D-path (number of horizontal
279 	/// and vertical steps; differences between the old and new
280 	/// document) in the k-diagonal (vertical minus horizontal steps).
281 	void furthestDpathKdiagonal(int D, int k,
282 		DocRangePair const & rp, Direction direction);
283 
284 	/// Is there overlap between the forward and backward path
285 	bool overlap(int k, int D);
286 
287 	/// This function is called recursively by a divide and conquer
288 	/// algorithm. Each time, the string is divided into two split
289 	/// around the middle snake.
290 	void diff_i(DocRangePair const & rp);
291 
292 	/// Processes the split chunks. It either adds them as deleted,
293 	/// as added, or call diff_i for further processing.
294 	void diffPart(DocRangePair const & rp);
295 
296 	/// Runs the algorithm for the inset located at /c it and /c it_n
297 	/// and adds the result to /c pars.
298 	void diffInset(Inset * inset, DocPair const & p);
299 
300 	/// Adds the snake to the destination buffer. The algorithm will
301 	/// recursively be applied to any InsetTexts that are within the snake.
302 	void processSnake(DocRangePair const & rp);
303 
304 	/// Writes the range to the destination buffer
305 	void writeToDestBuffer(DocRange const & range,
306 		Change::Type type = Change::UNCHANGED);
307 
308 	/// Writes the paragraph list to the destination buffer
309 	void writeToDestBuffer(ParagraphList const & copy_pars) const;
310 
311 	/// The length of the old chunk currently processed
312 	int n_;
313 	/// The length of the new chunk currently processed
314 	int m_;
315 	/// The offset diagonal of the reverse path of the
316 	/// currently processed chunk
317 	int offset_reverse_diagonal_;
318 	/// Is the offset odd or even ?
319 	bool odd_offset_;
320 
321 	/// The thread object, used to emit signals to the GUI
322 	Compare const & compare_;
323 
324 	/// The buffer containing text that will be marked as old
325 	Buffer const * old_buf_;
326 	/// The buffer containing text that will be marked as new
327 	Buffer const * new_buf_;
328 	/// The buffer containing text that will be marked as new
329 	Buffer const * dest_buf_;
330 
331 	/// The paragraph list of the destination buffer
332 	ParagraphList * dest_pars_;
333 
334 	/// The level of recursion
335 	int recursion_level_;
336 
337 	/// The number of nested insets at this level
338 	int nested_inset_level_;
339 
340 	/// The position/snake in the old/new document
341 	/// of the forward/reverse search
342 	compl_vector<DocIterator> ofp;
343 	compl_vector<DocIterator> nfp;
344 	compl_vector<DocIterator> ofs;
345 	compl_vector<DocIterator> nfs;
346 	compl_vector<DocIterator> orp;
347 	compl_vector<DocIterator> nrp;
348 	compl_vector<DocIterator> ors;
349 	compl_vector<DocIterator> nrs;
350 
351 	/// The number of differences in the path the algorithm
352 	/// is currently processing.
353 	int D_;
354 };
355 
356 /////////////////////////////////////////////////////////////////////
357 //
358 // Compare
359 //
360 /////////////////////////////////////////////////////////////////////
361 
Compare(Buffer const * new_buf,Buffer const * old_buf,Buffer * const dest_buf,CompareOptions const & options)362 Compare::Compare(Buffer const * new_buf, Buffer const * old_buf,
363 	Buffer * const dest_buf, CompareOptions const & options)
364 	: new_buffer(new_buf), old_buffer(old_buf), dest_buffer(dest_buf),
365 	  options_(options), pimpl_(new Impl(*this))
366 {
367 	connect(&status_timer_, SIGNAL(timeout()),
368 		this, SLOT(doStatusMessage()));
369 	status_timer_.start(1000);
370 }
371 
372 
doStatusMessage()373 void Compare::doStatusMessage()
374 {
375 	statusMessage(pimpl_->status());
376 }
377 
378 
run()379 void Compare::run()
380 {
381 	if (!dest_buffer || !new_buffer || !old_buffer)
382 		return;
383 
384 	// Copy the buffer params to the destination buffer
385 	dest_buffer->params() = options_.settings_from_new
386 		? new_buffer->params() : old_buffer->params();
387 	// Copy extra authors to the destination buffer
388 	AuthorList const & extra_authors = options_.settings_from_new ?
389 		old_buffer->params().authors() : new_buffer->params().authors();
390 	AuthorList::Authors::const_iterator it = extra_authors.begin();
391 	for (; it != extra_authors.end(); ++it)
392 		dest_buffer->params().authors().record(*it);
393 
394 	// We will need this later
395 	DocumentClassConstPtr const olddc =
396 		dest_buffer->params().documentClassPtr();
397 	// We do not want to share the DocumentClass with the other Buffer.
398 	// See bug #10295.
399 	dest_buffer->params().makeDocumentClass();
400 
401 	doStatusMessage();
402 	// Do the real work
403 	if (!doCompare())
404 		return;
405 
406 	// The comparison routine simply copies the paragraphs over into the
407 	// new buffer with the document class from wherever they came from.
408 	// So we need to reset the document class of all the paragraphs.
409 	// See bug #10295.
410 	ErrorList el;
411 	cap::switchBetweenClasses(
412 			olddc, dest_buffer->params().documentClassPtr(),
413 			static_cast<InsetText &>(dest_buffer->inset()), el);
414 
415 	finished(pimpl_->abort_);
416 	return;
417 }
418 
419 
doCompare()420 int Compare::doCompare()
421 {
422 	return pimpl_->diff(new_buffer, old_buffer, dest_buffer);
423 }
424 
425 
abort()426 void Compare::abort()
427 {
428 	pimpl_->abort_ = true;
429 	condition_.wakeOne();
430 	wait();
431 	pimpl_->abort_ = false;
432 }
433 
434 
getParagraphList(DocRange const & range,ParagraphList & pars)435 static void getParagraphList(DocRange const & range,
436 	ParagraphList & pars)
437 {
438 	// Clone the paragraphs within the selection.
439 	pit_type startpit = range.from.pit();
440 	pit_type endpit = range.to.pit();
441 	ParagraphList const & ps_ = range.text()->paragraphs();
442 	ParagraphList tmp_pars(lyx::next(ps_.begin(), startpit),
443 		lyx::next(ps_.begin(), endpit + 1));
444 
445 	// Remove the end of the last paragraph; afterwards, remove the
446 	// beginning of the first paragraph. Keep this order - there may only
447 	// be one paragraph!
448 	Paragraph & back = tmp_pars.back();
449 	back.eraseChars(range.to.pos(), back.size(), false);
450 	Paragraph & front = tmp_pars.front();
451 	front.eraseChars(0, range.from.pos(), false);
452 
453 	pars.insert(pars.begin(), tmp_pars.begin(), tmp_pars.end());
454 }
455 
456 
equal(Inset const * i_o,Inset const * i_n)457 static bool equal(Inset const * i_o, Inset const * i_n)
458 {
459 	if (!i_o || !i_n)
460 		return false;
461 
462 	// Different types of insets
463 	if (i_o->lyxCode() != i_n->lyxCode())
464 		return false;
465 
466 	// Editable insets are assumed to be the same as they are of the
467 	// same type. If we later on decide that we insert them in the
468 	// document as being unchanged, we will run the algorithm on the
469 	// contents of the two insets.
470 	// FIXME: This fails if the parameters of the insets differ.
471 	// FIXME: We do not recurse into InsetTabulars.
472 	// FIXME: We need methods inset->equivalent(inset).
473 	if (i_o->editable() && !i_o->asInsetMath()
474 		  && i_o->asInsetText())
475 		return true;
476 
477 	ostringstream o_os;
478 	ostringstream n_os;
479 	i_o->write(o_os);
480 	i_n->write(n_os);
481 	return o_os.str() == n_os.str();
482 }
483 
484 
equal(DocIterator & o,DocIterator & n)485 static bool equal(DocIterator & o, DocIterator & n)
486 {
487 	// Explicitly check for this, so we won't call
488 	// Paragraph::getChar for the last pos.
489 	bool const o_lastpos = o.pos() == o.lastpos();
490 	bool const n_lastpos = n.pos() == n.lastpos();
491 	if (o_lastpos || n_lastpos)
492 		return o_lastpos && n_lastpos;
493 
494 	Paragraph const & old_par = o.text()->getPar(o.pit());
495 	Paragraph const & new_par = n.text()->getPar(n.pit());
496 
497 	char_type const c_o = old_par.getChar(o.pos());
498 	char_type const c_n = new_par.getChar(n.pos());
499 	if (c_o != c_n)
500 		return false;
501 
502 	if (old_par.isInset(o.pos())) {
503 		Inset const * i_o = old_par.getInset(o.pos());
504 		Inset const * i_n = new_par.getInset(n.pos());
505 
506 		if (i_o && i_n)
507 			return equal(i_o, i_n);
508 	}
509 
510 	Font fo = old_par.getFontSettings(o.buffer()->params(), o.pos());
511 	Font fn = new_par.getFontSettings(n.buffer()->params(), n.pos());
512 	return fo == fn;
513 }
514 
515 
516 /// Traverses a snake in a certain direction. p points to a
517 /// position in the old and new file and they are synchronously
518 /// moved along the snake. The function returns true if a snake
519 /// was found.
traverseSnake(DocPair & p,DocRangePair const & range,Direction direction)520 static bool traverseSnake(DocPair & p, DocRangePair const & range,
521 	Direction direction)
522 {
523 	bool ret = false;
524 	DocPair const & p_end =
525 		direction == Forward ? range.to() : range.from();
526 
527 	while (p != p_end) {
528 		if (direction == Backward)
529 			--p;
530 		if (!equal(p.o, p.n)) {
531 			if (direction == Backward)
532 				++p;
533 			return ret;
534 		}
535 		if (direction == Forward)
536 			++p;
537 		ret = true;
538 	}
539 	return ret;
540 }
541 
542 
543 /////////////////////////////////////////////////////////////////////
544 //
545 // Compare::Impl
546 //
547 /////////////////////////////////////////////////////////////////////
548 
549 
furthestDpathKdiagonal(int D,int k,DocRangePair const & rp,Direction direction)550 void Compare::Impl::furthestDpathKdiagonal(int D, int k,
551 	 DocRangePair const & rp, Direction direction)
552 {
553 	compl_vector<DocIterator> & op = direction == Forward ? ofp : orp;
554 	compl_vector<DocIterator> & np = direction == Forward ? nfp : nrp;
555 	compl_vector<DocIterator> & os = direction == Forward ? ofs : ors;
556 	compl_vector<DocIterator> & ns = direction == Forward ? nfs : nrs;
557 
558 	// A vertical step means stepping one character in the new document.
559 	bool vertical_step = k == -D;
560 	if (!vertical_step && k != D) {
561 		vertical_step = direction == Forward
562 			? op[k - 1] < op[k + 1] : op[k - 1] > op[k + 1];
563 	}
564 
565 	// Where do we take the step from ?
566 	int const kk = vertical_step ? k + 1 : k - 1;
567 	DocPair p(op[kk], np[kk]);
568 	DocPair const s(os[kk], ns[kk]);
569 
570 	// If D==0 we simulate a vertical step from (0,-1) by doing nothing.
571 	if (D != 0) {
572 		// Take a step
573 		if (vertical_step && direction == Forward)
574 			step(p.n, rp.n.to, direction);
575 		else if (vertical_step && direction == Backward)
576 			step(p.n, rp.n.from, direction);
577 		else if (!vertical_step && direction == Forward)
578 			step(p.o, rp.o.to, direction);
579 		else if (!vertical_step && direction == Backward)
580 			step(p.o, rp.o.from, direction);
581 	}
582 
583 	// Traverse snake
584 	if (traverseSnake(p, rp, direction)) {
585 		// Record last snake
586 		os[k] = p.o;
587 		ns[k] = p.n;
588 	} else {
589 		// Copy last snake from the previous step
590 		os[k] = s.o;
591 		ns[k] = s.n;
592 	}
593 
594 	//Record new position
595 	op[k] = p.o;
596 	np[k] = p.n;
597 }
598 
599 
overlap(int k,int D)600 bool Compare::Impl::overlap(int k, int D)
601 {
602 	// To generalize for the forward and reverse checks
603 	int kk = offset_reverse_diagonal_ - k;
604 
605 	// Can we have overlap ?
606 	if (kk <= D && kk >= -D) {
607 		// Do we have overlap ?
608 		if (odd_offset_)
609 			return ofp[k] >= orp[kk] && nfp[k] >= nrp[kk];
610 		else
611 			return ofp[kk] >= orp[k] && nfp[kk] >= nrp[k];
612 	}
613 	return false;
614 }
615 
616 
retrieveMiddleSnake(int k,int D,Direction direction,DocPair & middle_snake)617 Compare::Impl::SnakeResult Compare::Impl::retrieveMiddleSnake(
618 	int k, int D, Direction direction, DocPair & middle_snake)
619 {
620 	compl_vector<DocIterator> & os = direction == Forward ? ofs : ors;
621 	compl_vector<DocIterator> & ns = direction == Forward ? nfs : nrs;
622 	compl_vector<DocIterator> & os_r = direction == Forward ? ors : ofs;
623 	compl_vector<DocIterator> & ns_r = direction == Forward ? nrs : nfs;
624 
625 	// The diagonal while doing the backward search
626 	int kk = -k + offset_reverse_diagonal_;
627 
628 	// Did we find a snake ?
629 	if (os[k].empty() && os_r[kk].empty()) {
630 		// No, there is no snake at all, in which case
631 		// the length of the shortest edit script is M+N.
632 		LATTEST(2 * D - odd_offset_ == m_ + n_);
633 		return NoSnake;
634 	}
635 
636 	if (os[k].empty()) {
637 		// Yes, but there is only 1 snake and we found it in the
638 		// reverse path.
639 		middle_snake.o = os_r[kk];
640 		middle_snake.n = ns_r[kk];
641 		return SingleSnake;
642 	}
643 
644 	middle_snake.o = os[k];
645 	middle_snake.n = ns[k];
646 	return NormalSnake;
647 }
648 
649 
findMiddleSnake(DocRangePair const & rp,DocPair & middle_snake)650 int Compare::Impl::findMiddleSnake(DocRangePair const & rp,
651 	DocPair & middle_snake)
652 {
653 	// The lengths of the old and new chunks.
654 	n_ = rp.o.length();
655 	m_ = rp.n.length();
656 
657 	// Forward paths are centered around the 0-diagonal; reverse paths
658 	// are centered around the diagonal N - M. (Delta in the article)
659 	offset_reverse_diagonal_ = n_ - m_;
660 
661 	// If the offset is odd, only check for overlap while extending forward
662     // paths, otherwise only check while extending reverse paths.
663 	odd_offset_ = (offset_reverse_diagonal_ % 2 != 0);
664 
665 	ofp.reset(rp.o.from);
666 	nfp.reset(rp.n.from);
667 	ofs.reset(DocIterator());
668 	nfs.reset(DocIterator());
669 	orp.reset(rp.o.to);
670 	nrp.reset(rp.n.to);
671 	ors.reset(DocIterator());
672 	nrs.reset(DocIterator());
673 
674 	// In the formula below, the "+ 1" ensures we round like ceil()
675 	int const D_max = (m_ + n_ + 1)/2;
676 	// D is the number of horizontal and vertical steps, i.e.
677 	// different characters in the old and new chunk.
678 	for (int D = 0; D <= D_max; ++D) {
679 		// to be used in the status messages
680 		D_ = D;
681 
682 		// Forward and reverse paths
683 		for (int f = 0; f < 2; ++f) {
684 			Direction direction = f == 0 ? Forward : Backward;
685 
686 			// Diagonals between -D and D can be reached by a D-path
687 			for (int k = -D; k <= D; k += 2) {
688 				// Find the furthest reaching D-path on this diagonal
689 				furthestDpathKdiagonal(D, k, rp, direction);
690 
691 				// Only check for overlap for forward paths if the offset is odd
692 				// and only for reverse paths if the offset is even.
693 				if (odd_offset_ == (direction == Forward)) {
694 
695 					// Do the forward and backward paths overlap ?
696 					if (overlap(k, D - odd_offset_)) {
697 						retrieveMiddleSnake(k, D, direction, middle_snake);
698 						return 2 * D - odd_offset_;
699 					}
700 				}
701 				if (abort_)
702 					return 0;
703 			}
704 		}
705 	}
706 	// This should never be reached
707 	return -2;
708 }
709 
710 
diff(Buffer const * new_buf,Buffer const * old_buf,Buffer const * dest_buf)711 bool Compare::Impl::diff(Buffer const * new_buf, Buffer const * old_buf,
712 	Buffer const * dest_buf)
713 {
714 	if (!new_buf || !old_buf || !dest_buf)
715 		return false;
716 
717 	old_buf_ = old_buf;
718 	new_buf_ = new_buf;
719 	dest_buf_ = dest_buf;
720 	dest_pars_ = &dest_buf->inset().asInsetText()->paragraphs();
721 	dest_pars_->clear();
722 
723 	recursion_level_ = 0;
724 	nested_inset_level_ = 0;
725 
726 	DocRangePair rp(old_buf_, new_buf_);
727 
728 	DocPair from = rp.from();
729 	traverseSnake(from, rp, Forward);
730 	DocRangePair const snake(rp.from(), from);
731 	processSnake(snake);
732 
733 	// Start the recursive algorithm
734 	DocRangePair rp_new(from, rp.to());
735 	if (!rp_new.o.empty() || !rp_new.n.empty())
736 		diff_i(rp_new);
737 
738 	for (pit_type p = 0; p < (pit_type)dest_pars_->size(); ++p) {
739 		(*dest_pars_)[p].setBuffer(const_cast<Buffer &>(*dest_buf));
740 		(*dest_pars_)[p].setInsetOwner(&dest_buf_->inset());
741 	}
742 
743 	return true;
744 }
745 
746 
diff_i(DocRangePair const & rp)747 void Compare::Impl::diff_i(DocRangePair const & rp)
748 {
749 	if (abort_)
750 		return;
751 
752 	// The middle snake
753 	DocPair middle_snake;
754 
755 	// Divides the problem into two smaller problems, split around
756 	// the snake in the middle.
757 	int const L_ses = findMiddleSnake(rp, middle_snake);
758 
759 	// Set maximum of progress bar
760 	if (++recursion_level_ == 1)
761 		compare_.progressMax(L_ses);
762 
763 	// There are now three possibilities: the strings were the same,
764 	// the strings were completely different, or we found a middle
765 	// snake and we can split the string into two parts to process.
766 	if (L_ses == 0)
767 		// Two the same strings (this must be a very rare case, because
768 		// usually this will be part of a snake adjacent to these strings).
769 		writeToDestBuffer(rp.o);
770 
771 	else if (middle_snake.o.empty()) {
772 		// Two totally different strings
773 		writeToDestBuffer(rp.o, Change::DELETED);
774 		writeToDestBuffer(rp.n, Change::INSERTED);
775 
776 	} else {
777 		// Retrieve the complete snake
778 		DocPair first_part_end = middle_snake;
779 		traverseSnake(first_part_end, rp, Backward);
780 		DocRangePair first_part(rp.from(), first_part_end);
781 
782 		DocPair second_part_begin = middle_snake;
783 		traverseSnake(second_part_begin, rp, Forward);
784 		DocRangePair second_part(second_part_begin, rp.to());
785 
786 		// Split the string in three parts:
787 		// 1. in front of the snake
788 		diffPart(first_part);
789 
790 		// 2. the snake itself, and
791 		DocRangePair const snake(first_part.to(), second_part.from());
792 		processSnake(snake);
793 
794 		// 3. behind the snake.
795 		diffPart(second_part);
796 	}
797 	--recursion_level_;
798 }
799 
800 
diffPart(DocRangePair const & rp)801 void Compare::Impl::diffPart(DocRangePair const & rp)
802 {
803 	// Is there a finite length string in both buffers, if not there
804 	// is an empty string and we write the other one to the buffer.
805 	if (!rp.o.empty() && !rp.n.empty())
806 		diff_i(rp);
807 
808 	else if (!rp.o.empty())
809 		writeToDestBuffer(rp.o, Change::DELETED);
810 
811 	else if (!rp.n.empty())
812 		writeToDestBuffer(rp.n, Change::INSERTED);
813 }
814 
815 
diffInset(Inset * inset,DocPair const & p)816 void Compare::Impl::diffInset(Inset * inset, DocPair const & p)
817 {
818 	// Find the dociterators for the beginning and the
819 	// end of the inset, for the old and new document.
820 	DocRangePair const rp = stepIntoInset(p);
821 
822 	// Recurse into the inset. Temporarily replace the dest_pars
823 	// paragraph list by the paragraph list of the nested inset.
824 	ParagraphList * backup_dest_pars = dest_pars_;
825 	dest_pars_ = &inset->asInsetText()->text().paragraphs();
826 	dest_pars_->clear();
827 
828 	++nested_inset_level_;
829 	diff_i(rp);
830 	--nested_inset_level_;
831 
832 	dest_pars_ = backup_dest_pars;
833 }
834 
835 
processSnake(DocRangePair const & rp)836 void Compare::Impl::processSnake(DocRangePair const & rp)
837 {
838 	ParagraphList pars;
839 	getParagraphList(rp.o, pars);
840 
841 	// Find insets in this paragaph list
842 	DocPair it = rp.from();
843 	for (; it.o < rp.o.to; ++it) {
844 		Inset * inset = it.o.text()->getPar(it.o.pit()).getInset(it.o.pos());
845 		if (inset && inset->editable() && inset->asInsetText()) {
846 			// Find the inset in the paragraph list that will be pasted into
847 			// the final document. The contents of the inset will be replaced
848 			// by the output of the algorithm below.
849 			pit_type const pit = it.o.pit() - rp.o.from.pit();
850 			pos_type const pos = pit ? it.o.pos() : it.o.pos() - rp.o.from.pos();
851 			inset = pars[pit].getInset(pos);
852 			LASSERT(inset, continue);
853 			diffInset(inset, it);
854 		}
855 	}
856 	writeToDestBuffer(pars);
857 }
858 
859 
writeToDestBuffer(DocRange const & range,Change::Type type)860 void Compare::Impl::writeToDestBuffer(DocRange const & range,
861 	Change::Type type)
862 {
863 	ParagraphList pars;
864 	getParagraphList(range, pars);
865 
866 	pos_type size = 0;
867 
868 	// Set the change
869 	ParagraphList::iterator it = pars.begin();
870 	for (; it != pars.end(); ++it) {
871 		it->setChange(Change(type));
872 		size += it->size();
873 	}
874 
875 	writeToDestBuffer(pars);
876 
877 	if (nested_inset_level_ == 0)
878 		compare_.progress(size);
879 }
880 
881 
writeToDestBuffer(ParagraphList const & pars) const882 void Compare::Impl::writeToDestBuffer(ParagraphList const & pars) const
883 {
884 	pit_type const pit = dest_pars_->size() - 1;
885 	dest_pars_->insert(dest_pars_->end(), pars.begin(), pars.end());
886 	if (pit >= 0)
887 		mergeParagraph(dest_buf_->params(), *dest_pars_, pit);
888 }
889 
890 
891 #include "moc_Compare.cpp"
892 
893 } // namespace lyx
894