Swiftdiff options
| author | Remko Tronçon <git@el-tramo.be> | 2011-07-01 07:30:24 (GMT) |
|---|---|---|
| committer | Remko Tronçon <git@el-tramo.be> | 2011-07-03 22:53:56 (GMT) |
| commit | f2bbeeae4f277ab02edee8fb39cbd397931595e2 (patch) | |
| tree | 61208211827f0ca6da152e72216b56ebd324a6e3 /Swift/Controllers/Roster/LeastCommonSubsequence.h | |
| parent | e4c1ffda13c4f7da7e2e8dd955b859d030134cbc (diff) | |
| download | swift-f2bbeeae4f277ab02edee8fb39cbd397931595e2.zip swift-f2bbeeae4f277ab02edee8fb39cbd397931595e2.tar.bz2 | |
Implement TableRoster with roster diff.
Diffstat (limited to 'Swift/Controllers/Roster/LeastCommonSubsequence.h')
| -rw-r--r-- | Swift/Controllers/Roster/LeastCommonSubsequence.h | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/Swift/Controllers/Roster/LeastCommonSubsequence.h b/Swift/Controllers/Roster/LeastCommonSubsequence.h new file mode 100644 index 0000000..dd3c95a --- /dev/null +++ b/Swift/Controllers/Roster/LeastCommonSubsequence.h @@ -0,0 +1,106 @@ +/* + * Copyright (c) 2011 Remko Tronçon + * Licensed under the GNU General Public License v3. + * See Documentation/Licenses/GPLv3.txt for more information. + */ + +#pragma once + +#include <vector> + +namespace Swift { + using std::equal_to; + + namespace Detail { + template<typename XIt, typename YIt, typename Length, typename Predicate> + void computeLeastCommonSubsequenceMatrix(XIt xBegin, XIt xEnd, YIt yBegin, YIt yEnd, std::vector<Length>& result) { + size_t width = std::distance(xBegin, xEnd) + 1; + size_t height = std::distance(yBegin, yEnd) + 1; + result.resize(width * height); + + // Initialize first row & column + for (size_t i = 0; i < width; ++i) { + result[i] = 0; + } + for (size_t j = 0; j < height; ++j) { + result[j*width] = 0; + } + + // Compute the LCS lengths for subsets + Predicate predicate; + for (size_t i = 1; i < width; ++i) { + for (size_t j = 1; j < height; ++j) { + result[i + j*width] = (predicate(*(xBegin + i-1), *(yBegin + j-1)) ? result[(i-1) + (j-1)*width] + 1 : std::max(result[i + (j-1)*width], result[i-1 + (j*width)])); + } + } + } + } + + template<typename X, typename InsertRemovePredicate, typename UpdatePredicate> + void computeIndexDiff(const std::vector<X>& x, const std::vector<X>& y, std::vector<size_t>& updates, std::vector<size_t>& postUpdates, std::vector<size_t>& removes, std::vector<size_t>& inserts) { + InsertRemovePredicate insertRemovePredicate; + UpdatePredicate updatePredicate; + + // Find & handle common prefix (Optimization to reduce LCS matrix size) + typename std::vector<X>::const_iterator xBegin = x.begin(); + typename std::vector<X>::const_iterator yBegin = y.begin(); + while (xBegin < x.end() && yBegin < y.end() && insertRemovePredicate(*xBegin, *yBegin)) { + if (updatePredicate(*xBegin, *yBegin)) { + updates.push_back(std::distance(x.begin(), xBegin)); + postUpdates.push_back(std::distance(y.begin(), yBegin)); + } + ++xBegin; + ++yBegin; + } + size_t prefixLength = std::distance(x.begin(), xBegin); + + // Find & handle common suffix (Optimization to reduce LCS matrix size) + typename std::vector<X>::const_reverse_iterator xEnd = x.rbegin(); + typename std::vector<X>::const_reverse_iterator yEnd = y.rbegin(); + while (xEnd.base() > xBegin && yEnd.base() > yBegin && insertRemovePredicate(*xEnd, *yEnd)) { + if (updatePredicate(*xEnd, *yEnd)) { + updates.push_back(std::distance(x.begin(), xEnd.base()) - 1); + postUpdates.push_back(std::distance(y.begin(), yEnd.base()) - 1); + } + ++xEnd; + ++yEnd; + } + + // Compute lengths + size_t xLength = std::distance(xBegin, xEnd.base()); + size_t yLength = std::distance(yBegin, yEnd.base()); + + // Compute LCS matrix + std::vector<unsigned int> lcs; + Detail::computeLeastCommonSubsequenceMatrix<typename std::vector<X>::const_iterator, typename std::vector<X>::const_iterator, unsigned int, InsertRemovePredicate>(xBegin, xEnd.base(), yBegin, yEnd.base(), lcs); + + // Process LCS matrix + size_t i = xLength; + size_t j = yLength; + const size_t width = xLength + 1; + while (true) { + if (i > 0 && j > 0 && insertRemovePredicate(x[prefixLength + i-1], y[prefixLength + j-1])) { + // x[i-1] same + if (updatePredicate(x[prefixLength + i - 1], y[prefixLength + j - 1])) { + updates.push_back(prefixLength + i-1); + postUpdates.push_back(prefixLength + j-1); + } + i -= 1; + j -= 1; + } + else if (j > 0 && (i == 0 || lcs[i + (j-1)*width] >= lcs[i-1 + j*width])) { + // y[j-1] added + inserts.push_back(prefixLength + j-1); + j -= 1; + } + else if (i > 0 && (j == 0 || lcs[i + (j-1)*width] < lcs[i-1 + j*width])) { + // x[i-1] removed + removes.push_back(prefixLength + i-1); + i -= 1; + } + else { + break; + } + } + } +} |