lyx_mirror/src/Compare.cpp
Vincent van Ravesteijn 68edfdafc3 Unify traverse_snake_back and traverse_snake_forw and make it more general for future purposes.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@32922 a592a061-630c-0410-9148-cb99ea01b6c8
2010-01-09 21:17:10 +00:00

602 lines
14 KiB
C++

/**
* \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 <config.h>
#include "Compare.h"
#include "BufferParams.h"
#include "Changes.h"
#include "insets/InsetText.h"
#include "support/lassert.h"
#include <boost/next_prior.hpp>
using namespace std;
using namespace lyx::support;
namespace lyx {
void step_forward(DocIterator & dit)
{
dit.top().forwardPos();
}
void step_backward(DocIterator & dit)
{
dit.top().backwardPos();
}
bool step_forward(DocIterator & dit, DocIterator const & end)
{
if (dit == end)
return false;
step_forward(dit);
return true;
}
bool step_backward(DocIterator & dit, DocIterator const & beg)
{
if (dit == beg)
return false;
step_backward(dit);
return true;
}
/**
* A pair of two DocIterators that form a range.
*/
class DocRange {
public:
DocRange(DocIterator from_, DocIterator 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
{
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();
size_t length = 0;
for (; pit != end_it; ++pit)
length += pit->size() + 1;
// The last paragraph has no paragraph-end
--length;
return length;
}
class DocPair {
public:
DocPair() {}
DocPair(DocIterator o_, DocIterator n_)
: o(o_), n(n_)
{}
bool operator!=(DocPair const & rhs) {
// this might not be intuitive but correct for our purpose
return o != rhs.o && n != rhs.n;
}
DocPair & operator++()
{
step_forward(o);
step_forward(n);
return *this;
}
DocPair & operator--()
{
step_backward(o);
step_backward(n);
return *this;
}
///
DocIterator o;
///
DocIterator n;
};
/**
* A pair of two DocRanges.
*/
class DocRangePair {
public:
DocRangePair(DocRange o_, DocRange n_)
: o(o_), n(n_)
{}
DocRangePair(DocPair from, DocPair 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;
};
DocRangePair stepIntoInset(DocPair const & inset_location)
{
DocRangePair rp(inset_location, inset_location);
rp.o.from.forwardPos();
rp.n.from.forwardPos();
step_forward(rp.o.to);
step_forward(rp.n.to);
rp.o.to.backwardPos();
rp.n.to.backwardPos();
return rp;
}
/**
* The implementation of the algorithm that does the comparison
* between two documents.
*/
class Compare::Impl {
public:
///
Impl(Compare const & compare)
: abort_(false), compare_(compare)
{}
///
~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_;
private:
/// Finds the middle snake and returns the length of the
/// shortest edit script.
int find_middle_snake(DocRangePair const & rp, DocPair & middle_snake);
/// 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 splitted chunks. It either adds them as deleted,
/// as added, or call diff_i for further processing.
void diff_part(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 diff_inset(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 process_snake(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 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_;
};
/////////////////////////////////////////////////////////////////////
//
// 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))
{
}
void Compare::run()
{
if (!dest_buffer || !new_buffer || !old_buffer)
return;
// Copy the buffer params to the new buffer
dest_buffer->params() = options_.settings_from_new
? new_buffer->params() : old_buffer->params();
// do the real work
if (!doCompare())
return;
finished(pimpl_->abort_);
return;
}
int Compare::doCompare()
{
return pimpl_->diff(new_buffer, old_buffer, dest_buffer);
}
void Compare::abort()
{
pimpl_->abort_ = true;
condition_.wakeOne();
wait();
pimpl_->abort_ = false;
}
void get_paragraph_list(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(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. 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());
}
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();
}
bool equal(DocIterator & o, DocIterator & n) {
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;
}
bool traverse_snake(DocPair & p, DocRangePair const & rp, bool forward)
{
bool ret = false;
DocPair const & p_end = forward ? rp.to() : rp.from();
while (p != p_end) {
if (!forward)
--p;
if (!equal(p.o, p.n)) {
if (!forward)
++p;
return ret;
}
if (forward)
++p;
ret = true;
}
return ret;
}
/////////////////////////////////////////////////////////////////////
//
// Compare::Impl
//
/////////////////////////////////////////////////////////////////////
int Compare::Impl::find_middle_snake(DocRangePair const & rp,
DocPair &)
{
N = rp.o.length();
M = rp.n.length();
return M+N;
}
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();
traverse_snake(from, rp, true);
DocRangePair const snake(rp.from(), from);
process_snake(snake);
// Start the recursive algorithm
diff_i(rp);
for (pit_type p = 0; p < (pit_type)dest_pars_->size(); ++p) {
(*dest_pars_)[p].setBuffer(const_cast<Buffer &>(*dest_buf));
(*dest_pars_)[p].setInsetOwner(&dest_buf_->inset());
}
return true;
}
void Compare::Impl::diff_i(DocRangePair const & rp)
{
// The middle snake
DocPair middle_snake;
// Divides the problem into two smaller problems, split around
// the snake in the middle.
int const L_ses = find_middle_snake(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;
traverse_snake(first_part_end, rp, false);
DocRangePair first_part(rp.from(), first_part_end);
DocPair second_part_begin = middle_snake;
traverse_snake(second_part_begin, rp, true);
DocRangePair second_part(second_part_begin, rp.to());
// Split the string in three parts:
// 1. in front of the snake
diff_part(first_part);
// 2. the snake itself, and
DocRangePair const snake(first_part.to(), second_part.from());
process_snake(snake);
// 3. behind the snake.
diff_part(second_part);
}
--recursion_level_;
}
void Compare::Impl::diff_part(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::diff_inset(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::process_snake(DocRangePair const & rp)
{
ParagraphList pars;
get_paragraph_list(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, /**/);
diff_inset(inset, it);
}
}
writeToDestBuffer(pars);
}
void Compare::Impl::writeToDestBuffer(DocRange const & range,
Change::Type type)
{
ParagraphList pars;
get_paragraph_list(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