File indexing completed on 2024-05-12 05:52:07

 /*
     SPDX-FileCopyrightText: 2007 Andreas Pakulat <apaku@gmx.de>
     SPDX-FileCopyrightText: 2020 Jonathan Verner <jonathan.verner@matfyz.cz>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 #include "gitdiff.h"
 
 #include <QDebug>
 #include <QRegularExpression>
 #include <QSharedData>
 #include <QString>
 #include <QUrl>
 
 /* A class representing a diff hunk (a collection of localized changes) */
 class DiffHunk
 {
 public:
     /* Metadata for the hunk */
     uint srcStart /**< the 1-based (!) start line number of the range in the source file where the hunk applies */
         ,
         srcCount /**< the size of the range (in # of lines) in the source where the hunk applies  (i.e. ctx lines + deleted lines)*/
         ,
         tgtStart /**< the 1-based (!) start line number of the range in the target file where the hunk applies */
         ,
         tgtCount /**< the size of the range (in # of lines) in the target where the hunk applies  (i.e. ctx lines + deleted lines)*/
         ,
         headingLineIdx /**< The 0-based line number (in the whole diff) of the hunk header line (the one starting with `@@`) */
         ;
     QString srcFile /**< The source filename */
         ,
         tgtFile /**< The target filename */
         ,
         heading /**< The heading of the hunk (the stuff in the header line after the position spec, i.e. after the second `@@`) */
         ;
     QStringList lines; /**< The lines comprising the hunk (excluding the header) */
 
     /**
      * @returns the 0-based line number (in the whole diff) of the last line contained in the hunk.
      */
     uint lastLineIdx() const
     {
         return headingLineIdx + lines.size();
     }
 
     /**
      * @param lineIdx the 0-based line number of the tested line in the whole diff
      * @returns true if the line is part of the diff and false otherwise
      * @note: Returns true also for the header line (the one starting with `@@`)
      */
     bool containsDiffLine(uint lineIdx) const
     {
         return headingLineIdx <= lineIdx && lineIdx <= lastLineIdx();
     }
 
     /**
      * Returns the index of the line within the hunk
      *
      * @param diffLineIdx the 0-based indes of the line in the diff
      *
      * @note assumes that the line is contained within the hunk
      * @note if the line is a header line, -1 is returned; otherwise the returned
      * number is the index of the line in the `lines` list
      */
     int diffLineToHunkLine(uint diffLineIdx) const
     {
         return diffLineIdx - (headingLineIdx + 1);
     }
 
     /**
      * A helper method to construct a hunk header from the provided info
      *
      * A hunk header has the following form:
      *
      *      @@ oldStart,oldCount newStart,newCount @@ heading
      * e.g.
      *      @@ -36,14 +36,28 @@ public:
      *
      * @returns the hunk header
      */
     static QString formatHeader(uint oldStart, uint oldCount, uint newStart, uint newCount, QString head);
 
     /**
      * The following operators define a PARTIAL order on the hunks list.
      * A hunk H is strictly below a hunk K iff the endline of H is strictly below
      * the start line of K. In particular, the only non-overlapping hunks are
      * ordered.
      */
     bool operator<(const DiffHunk &b) const
     {
         return lastLineIdx() < b.headingLineIdx;
     }
     bool operator<(uint line) const
     {
         return lastLineIdx() < line;
     }
     bool operator<=(const DiffHunk &b) const
     {
         return lastLineIdx() <= b.headingLineIdx;
     }
     bool operator<=(uint line) const
     {
         return lastLineIdx() <= line;
     }
     bool operator>(const DiffHunk &b) const
     {
         return headingLineIdx > b.lastLineIdx();
     }
     bool operator>(uint line) const
     {
         return headingLineIdx > line;
     }
     bool operator>=(const DiffHunk &b) const
     {
         return headingLineIdx >= b.lastLineIdx();
     }
     bool operator>=(uint line) const
     {
         return headingLineIdx >= line;
     }
 };
 
 /* RegExp matching a hunk header line */
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, HUNK_HEADER_RE, (QLatin1String("^@@ -([0-9,]+) \\+([0-9,]+) @@(.*)")))
 // static const auto HUNK_HEADER_RE = QRegularExpression(QStringLiteral("^@@ -([0-9,]+) \\+([0-9,]+) @@(.*)"));
 
 /* RegExp matching a meta line containing a source of target filename */
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, DIFF_FILENAME_RE, (QLatin1String("^[-+]{3} [ab]/(.*)")))
 
 /* RegExp matching a meta line (hunk header, filename, other info) */
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, META_LINE_RE, (QLatin1String("(^[-+]{3} )|^[^-+ ]")))
 
 /* RegExps matching conflict delimiting lines */
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, CONFLICT_START_RE, (QLatin1String("^<<<<<<<")))
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, CONFLICT_MID_RE, (QLatin1String("^=======")))
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, CONFLICT_END_RE, (QLatin1String("^>>>>>>>")))
 Q_GLOBAL_STATIC_WITH_ARGS(const QRegularExpression, CONFLICT_RE, (QLatin1String("(^>>>>>>>)|(^=======)|(^<<<<<<<)")))
 
 QString formatRange(uint start, uint count)
 {
     if (count == 1)
         return QString().setNum(start);
     return QString().setNum(start) + QLatin1Char(',') + QString().setNum(count);
 }
 
 std::pair<uint, uint> parseRange(const QString &range)
 {
     int commaPos = range.indexOf(QLatin1Char(','));
     if (commaPos > -1) {
         return {QStringView(range).sliced(0, commaPos).toInt(), QStringView(range).sliced(commaPos + 1).toInt()};
     }
     return {range.toInt(), 1};
 }
 
 /* Creates a hunk header line (starting with @@)
  *
  * Note: The line will not end with a newline */
 QString DiffHunk::formatHeader(uint oldStart, uint oldCount, uint newStart, uint newCount, QString head)
 {
     return QLatin1String("@@ -") + formatRange(oldStart, oldCount) + QLatin1String(" +") + formatRange(newStart, newCount) + QLatin1String(" @@") + head;
 }
 
 /**
  * Parses a unified diff into a list of "diff hunks" (each hunk starts with a
  * line starting with @@ and represents a collection of localized changes).
  *
  * @param diff a diff in git's unified diff format
  * @returns a list of hunk structures
  *
  * The diff is assumed to be a collection of hunks, where each hunk has the
  * following structure:
  *
  *   METADATA
  *   --- a/SOURCE_PATH
  *   +++ b/TARGET_PATH
  *   HUNK HEADER
  *   HUNK CONTENT
  *
  * All metadata lines match the @ref:META_LINE_RE regexp (starts with anything
  * except for a '+', '-' and ' ') and these are discarded except for the hunk
  * header and source/target path specifications. The path specifications
  * are assumed to apply to all following hunks until a new path specification
  * is found and are stored in the srcFileName and tgtFileName attributes of
  * the hunk structure.
  *
  *
  * Hunk Header
  * -----------
  *
  * The hunk header has the following form
  *
  *   @@ -SRC_OFFSET[, SRC_CHANGES_COUNT] +TGT_OFFSET[, TGT_CHANGES_COUNT] @@ Heading
  *
  * where the SRC_OFFSET is a 1-based line index pointing to the source file where
  * the hunk applies and TGT_OFFSET is a 1-based line index pointing to the target
  * file where the hunk applies. These are parsed into the srcStart and tgtStart
  * attributes of the hunk structure.
  *
  * The optional SRC_CHANGES_COUNTS (assumed to be 1 if not present) specifies the
  * number of context lines (starting with ' ') plus the number of deleted lines
  * (starting with '-'). Similarly, the optional TGT_CHANGES_COUNT specifies the
  * number of context lines plus the number of added lines (starting with '+').
  * These are parsed and stored in the srcCount and tgtCount attributes of the hunk
  * structure, but not checked (!). I.e. if the diff hunk has more/less changes then
  * specified, the returned hunk structure will have invalid src & tgt counts.
  *
  * Finally the Heading, used as a visual aid for users, is supposed to show the line
  * where the nearest enclosing function scope of the hunk starts. It is parsed and
  * stored in the heading attribute.
  *
  * Hunk Content
  * ------------
  *
  * The hunk content is a collection of lines which
  *
  *   1) start with '+' (additions); or
  *   2) start with '-' (deletions); or
  *   3) start with ' ' (context lines); or
  *   4) are empty (context lines); or
  *   5) are within conflict markers
  *
  * These lines are parsed and stored in the lines attribute of the hunk structure.
  * The parsing of the hunk stops when a METADATA line (outside of conflict markers)
  * is encountered or the end of the file is reached.
  *
  * Conflict Markers
  * ----------------
  *
  * Conflict markers are collections of lines of the form:
  *
  *   >>>>>>> our ref
  *   our content
  *   ...
  *   =======
  *   their content
  *   ...
  *   <<<<<<< their ref
  *
  * And show content which a merge was not able to merge automatically.
  * Strictly speaking, these should not appear in diffs, but git diff
  * generates them anyway for files with unresolved conflicts.
  */
 std::vector<DiffHunk> parseHunks(VcsDiff &diff)
 {
     std::vector<DiffHunk> ret;
     int lineNo = -1;
     QString curSrcFileName, curTgtFileName;
     QStringListIterator lines(diff.diff().split(QLatin1Char('\n')));
     while (lines.hasNext()) {
         lineNo++;
         auto curln = lines.next();
         auto m = DIFF_FILENAME_RE->match(curln);
         if (m.hasMatch()) {
             if (curln.startsWith(QLatin1Char('-')))
                 curSrcFileName = m.captured(1);
             else if (curln.startsWith(QLatin1Char('+')))
                 curTgtFileName = m.captured(1);
             continue;
         }
         m = HUNK_HEADER_RE->match(curln);
         if (!m.hasMatch())
             continue;
         const auto oldRange = parseRange(m.captured(1));
         const auto newRange = parseRange(m.captured(2));
         const auto heading = m.captured(3);
         uint firstLineIdx = lineNo;
         QStringList hunkLines;
         while (lines.hasNext() && (CONFLICT_START_RE->match(lines.peekNext()).hasMatch() || !META_LINE_RE->match(lines.peekNext()).hasMatch())) {
             // Consume the conflict
             if (CONFLICT_START_RE->match(lines.peekNext()).hasMatch()) {
                 lineNo++;
                 hunkLines << lines.next();
                 while (lines.hasNext() && !CONFLICT_END_RE->match(lines.peekNext()).hasMatch()) {
                     lineNo++;
                     hunkLines << lines.next();
                 }
                 if (!CONFLICT_END_RE->match(lines.peekNext()).hasMatch()) {
                     qWarning() << "Invalid diff format, end of file reached before conflict finished";
                     qDebug() << diff.diff();
                     break;
                 }
             }
             lineNo++;
             hunkLines << lines.next();
         }
 
         // The number of filenames present in the diff should match the number
         // of hunks
         ret.push_back(
             DiffHunk{oldRange.first, oldRange.second, newRange.first, newRange.second, firstLineIdx, curSrcFileName, curTgtFileName, heading, hunkLines});
     }
 
     // If the diff ends with a newline, for the last hunk, when splitting into lines above
     // we will always get an empty string at the end, which we now remove
     if (diff.diff().endsWith(QLatin1Char('\n'))) {
         if (ret.size() > 0 && ret.back().lines.size() > 0) {
             ret.back().lines.pop_back();
         } else {
             qWarning() << "Failed to parse a diff, produced no hunks";
             qDebug() << "Failed diff:" << diff.diff();
         }
     }
 
     return ret;
 }
 
 class VcsDiffPrivate
 {
 public:
     QUrl baseDiff;
     QString diff;
     uint depth = 0;
     std::vector<DiffHunk> hunks;
 
     enum Dest {
         SRC = '-',
         TGT = '+',
     };
 
     /**
      * Maps a line position in the diff to a corresponding line position in the destination file.
      *
      * @param line a 0-based line position in the diff
      * @param dest specifies the destination file to map to:
      *             either SRC (the source file, '-') or TGT (the target file, '+')
      * @returns the 0-based line position in the destination file or -1 if no such position exists.
      */
     int mapDiffLine(const uint line, const Dest dest) const
     {
         const QLatin1Char skipChar = (dest == SRC) ? QLatin1Char(TGT) : QLatin1Char(SRC);
         for (const auto &h : hunks) {
             if (h.containsDiffLine(line)) {
                 int hunkPos = h.diffLineToHunkLine(line);
 
                 // The line refers to the heading line
                 if (hunkPos < 0)
                     return -1;
 
                 // Any lines in the diff hunk which come before line and come from the opposite
                 // of dest should not be counted (they are not present in the dest)
                 int skipCount = 0;
                 for (int i = 0; i < hunkPos; i++) {
                     if (h.lines.at(i).startsWith(skipChar))
                         skipCount++;
                 }
 
                 // Any lines in the diff hunk which come from the second part (src)/ first part (tgt)
                 // of a conflict should not be counted either
                 bool inConflict = false; // This is set so that a line inside a conflict is recognized as a valid line
                 for (int i = 0; i < hunkPos; i++) {
                     if (CONFLICT_START_RE->match(h.lines.at(i)).hasMatch()) {
                         skipCount++; // skip the conflict marker line
                         if (dest == TGT) {
                             while ((++i) < hunkPos && !CONFLICT_MID_RE->match(h.lines.at(i)).hasMatch()) {
                                 skipCount++;
                             }
                         } else {
                             inConflict = true;
                         }
                     }
                     if (CONFLICT_MID_RE->match(h.lines.at(i)).hasMatch()) {
                         skipCount++; // skip the conflict marker line
                         if (dest == SRC) {
                             while ((++i) < hunkPos && !CONFLICT_END_RE->match(h.lines.at(i)).hasMatch())
                                 skipCount++;
                         } else {
                             inConflict = true;
                         }
                     }
                     if (CONFLICT_END_RE->match(h.lines.at(i)).hasMatch()) {
                         skipCount++; // skip the conflict marker line
                         inConflict = false;
                     }
                 }
 
                 auto ln = h.lines[hunkPos];
 
                 // This works around the fact that inConflict is set even if hunkPos
                 // ends up hitting a conflict marker
                 if (CONFLICT_RE->match(ln).hasMatch())
                     return -1;
 
                 if (ln.startsWith(QLatin1Char(dest)) || ln.startsWith(QLatin1Char(' ')) || ln.isEmpty() || inConflict) {
                     if (dest == SRC)
                         // The -1 accounts for the fact that srcStart is 1-based
                         // but we need to return 0-based line numbers
                         return h.srcStart - 1 + hunkPos - skipCount;
                     else
                         // The -1 accounts for the fact that srcStart is 1-based
                         // but we need to return 0-based line numbers
                         return h.tgtStart - 1 + hunkPos - skipCount;
                 } else
                     return -1;
             }
         }
         return -1;
     }
 };
 
 VcsDiff VcsDiff::subDiffHunk(const uint line, DiffDirection dir) const
 {
     for (const auto &hunk : d->hunks) {
         if (hunk.containsDiffLine(line)) {
             return subDiff(hunk.headingLineIdx, hunk.lastLineIdx(), dir);
         }
     }
 
     VcsDiff emptyDiff;
     emptyDiff.setBaseDiff(d->baseDiff);
     emptyDiff.setDepth(d->depth);
     emptyDiff.setDiff(d->diff.mid(0, d->diff.indexOf(QStringLiteral("@@"))));
     return emptyDiff;
 }
 
 VcsDiff VcsDiff::subDiff(const uint startLine, const uint endLine, DiffDirection dir) const
 {
     // Code adapted from cola/diffparse.py
     enum LineType { ADD = '+', DEL = '-', CTX = ' ', NO_NEWLINE = '\\' };
 
     VcsDiff ret;
     ret.setBaseDiff(baseDiff());
     ret.setDepth(depth());
 
     QStringList lines;
     for (const auto &hunk : d->hunks) {
         // Skip hunks before the first line
         if (hunk < startLine)
             continue;
 
         // Skip hunks after the last line
         if (hunk > endLine)
             break;
 
         std::map<LineType, int> counts = {{ADD, 0}, {DEL, 0}, {CTX, 0}, {NO_NEWLINE, 0}};
         QStringList filteredLines;
 
         // Will be set if the previous line in a hunk was
         // skipped because it was not in the selected range
         bool prevSkipped = false;
 
         uint lnIdx = hunk.headingLineIdx;
 
         // Store the number of skipped lines which start the hunk
         // (i.e. lines before a first deletion (addition in case of reverse)
         // so that we can adjust the start appropriately
         int startOffset = 0;
         const auto _lines = QStringList(hunk.lines.constBegin(), hunk.lines.constEnd());
         for (const auto &line : _lines) {
             lnIdx++;
             LineType tp = line.length() > 0 ? (LineType)line[0].toLatin1() : (LineType)0;
             QString content = line.mid(1);
 
             if (dir == Reverse) {
                 if (tp == ADD)
                     tp = DEL;
                 else if (tp == DEL)
                     tp = ADD;
             }
 
             if (lnIdx < startLine || endLine < lnIdx) {
                 // skip additions (or deletions if reverse) that are not in range
                 if (tp == ADD) {
                     prevSkipped = true;
                     // If we are before the range and
                     // so far we only encountered ADD (or DEL, in case of reverse) lines
                     // these will not be included in the subdiff hunk so we increase the startOffset
                     if (lnIdx < startLine && counts[CTX] == 0)
                         startOffset++;
                     continue;
                 }
                 // change deletions (or additions if reverse) that are not in range into context
                 if (tp == DEL)
                     tp = CTX;
             }
 
             // If the line immediately before a "No newline" line was
             // skipped (because it was an unselected addition) skip
             // the "No newline" line as well.
             if (tp == NO_NEWLINE && prevSkipped) {
                 if (lnIdx <= endLine)
                     startOffset++;
                 continue;
             }
 
             // Empty lines are context lines and we
             // preserve them
             if ((int)tp == 0) {
                 filteredLines << content;
                 tp = CTX;
             } else {
                 filteredLines << QLatin1Char(tp) + content;
             }
             counts[tp]++;
             prevSkipped = false;
         }
 
         // Skip hunks which have only context lines
         if (counts[ADD] + counts[DEL] == 0)
             continue;
 
         // Compute the start & counts of the hunks
         uint subSrcStart, subTgtStart;
         if (dir == Reverse) {
             subSrcStart = hunk.tgtStart + startOffset;
             subTgtStart = hunk.srcStart + startOffset;
         } else {
             subSrcStart = hunk.srcStart + startOffset;
             subTgtStart = hunk.tgtStart + startOffset;
         }
         uint subSrcCount = counts[CTX] + counts[DEL];
         uint subTgtCount = counts[CTX] + counts[ADD];
 
         // Prepend lines identifying the source files
         lines << QStringLiteral("--- a/") + ((dir == Reverse) ? hunk.tgtFile : hunk.srcFile);
         lines << QStringLiteral("+++ b/") + ((dir == Reverse) ? hunk.srcFile : hunk.tgtFile);
 
         lines << DiffHunk::formatHeader(subSrcStart, subSrcCount, subTgtStart, subTgtCount, hunk.heading);
         lines += filteredLines;
     }
     if (lines.size() > 2)
         ret.setDiff(lines.join(QLatin1Char('\n')) + QLatin1Char('\n'));
     return ret;
 }
 
 int VcsDiff::diffLineToSourceLine(const uint line) const
 {
     return d->mapDiffLine(line, VcsDiffPrivate::SRC);
 }
 
 int VcsDiff::diffLineToTargetLine(const uint line) const
 {
     return d->mapDiffLine(line, VcsDiffPrivate::TGT);
 }
 
 VcsDiff::VcsDiff()
     : d(new VcsDiffPrivate)
 {
 }
 
 VcsDiff::~VcsDiff() = default;
 
 VcsDiff::VcsDiff(VcsDiff &&rhs)
 {
     this->d = std::move(rhs.d);
 }
 
 bool VcsDiff::isEmpty() const
 {
     return d->diff.isEmpty();
 }
 
 QString VcsDiff::diff() const
 {
     return d->diff;
 }
 
 void VcsDiff::setDiff(const QString &s)
 {
     d->diff = s;
     d->hunks = parseHunks(*this);
 }
 
 QUrl VcsDiff::baseDiff() const
 {
     return d->baseDiff;
 }
 
 uint VcsDiff::depth() const
 {
     return d->depth;
 }
 
 void VcsDiff::setBaseDiff(const QUrl &url)
 {
     d->baseDiff = url;
 }
 
 void VcsDiff::setDepth(const uint depth)
 {
     d->depth = depth;
 }