/// <summary>
/// Gets th edit script of this line in comparison to its <see cref="Counterpart"/>.
/// The change edit script can then be used to color each letter position in the line
/// to indicate how one line can completely match the other using character based
/// change operations (insert, delete, change, none).
///
/// The method should only be invoked on demand (when a line is actually
/// displayed) - we should wait with pulling it until we have to have it for rendering.
///
/// This object will NOT cache the edit script so the caller should implement an external
/// caching algorithm to avoid multiple computations of the same answer.
///
/// Getting all intra-line diffs at once makes the whole process into an O(n^2) operation
/// instead of just an O(n) operation for line-by-line diffs. So we try to defer the
/// extra work until the user requests to see the changed line. It's still
/// the same amount of work if the user views every line, but it makes the
/// user interface more responsive to split it up like this.
/// </summary>
/// <param name="options"></param>
/// <returns></returns>
public EditScript GetChangeEditScript(ChangeDiffOptions options)
{
EditScript _changeEditScript = null;
if ( //_changeEditScript == null &&
_editType == EditType.Change && this.Counterpart != null)
{
if (this.FromA)
{
int trimCountA, trimCountB;
MyersDiff <char> diff = new MyersDiff <char>(
GetCharactersToDiff(this.text, options, out trimCountA),
GetCharactersToDiff(this.Counterpart.text, options, out trimCountB),
false); // We don't want Change edits; just Deletes and Inserts.
_changeEditScript = diff.Execute(null);
// If we trimmed/ignored leading whitespace, we have to offset each Edit to account for that.
foreach (Edit edit in _changeEditScript)
{
edit.Offset(trimCountA, trimCountB);
}
}
else if (this.Counterpart.FromA && this.Counterpart.Counterpart == this)
{
// Defer to the A line because its edit script changes A into B.
_changeEditScript = this.Counterpart.GetChangeEditScript(options);
}
}
return(_changeEditScript);
}
/**
* Tests the performance of MyersDiff for texts which are similar (not
* random data). The CPU time is measured and returned. Because of bad
* accuracy of CPU time information the diffs are repeated. During each
* repetition the interim CPU time is checked. The diff operation is
* repeated until we have seen the CPU time clock changed its value at least
* {@link #minCPUTimerTicks} times.
*
* @param characters
* the size of the diffed character sequences.
* @return performance data
*/
private PerfData test(int characters)
{
PerfData ret = new PerfData();
string a = DiffTestDataGenerator.generateSequence(characters, 971, 3);
string b = DiffTestDataGenerator.generateSequence(characters, 1621, 5);
CharArray ac = new CharArray(a);
CharArray bc = new CharArray(b);
MyersDiff myersDiff = null;
int cpuTimeChanges = 0;
long lastReadout = 0;
long interimTime = 0;
int repetitions = 0;
stopwatch.start();
while (cpuTimeChanges < minCPUTimerTicks && interimTime < longTaskBoundary)
{
myersDiff = new MyersDiff(ac, bc);
repetitions++;
interimTime = stopwatch.readout();
if (interimTime != lastReadout)
{
cpuTimeChanges++;
lastReadout = interimTime;
}
}
ret.runningTime = stopwatch.stop() / repetitions;
ret.N = (ac.size() + bc.size());
ret.D = myersDiff.getEdits().size();
return(ret);
}
public LineAndCommit[] Blame(Commit commit, string path)
{
var leaf = commit.Tree[path] as Leaf;
if (leaf == null)
{
throw new ArgumentException("The given path does not exist in this commit: " + path);
}
byte[] data = leaf.RawData;
IntList lineMap = RawParseUtils.lineMap(data, 0, data.Length);
var lines = new LineAndCommit[lineMap.size()];
var curText = new RawText(data);
Commit prevAncestor = commit;
Leaf prevLeaf = null;
Commit prevCommit = null;
int emptyLines = lineMap.size();
foreach (Commit ancestor in commit.Ancestors)
{
var cleaf = ancestor.Tree[path] as Leaf;
if (prevCommit != null && (cleaf == null || cleaf.Hash != prevLeaf.Hash))
{
byte[] prevData = prevLeaf.RawData;
if (prevData == null)
{
break;
}
var prevText = new RawText(prevData);
var differ = new MyersDiff(prevText, curText);
foreach (Edit e in differ.getEdits())
{
for (int n = e.BeginB; n < e.EndB; n++)
{
if (lines[n] == null)
{
lines[n] = CreateViewModel(GetLine(commit.Encoding, curText, n), prevCommit);
emptyLines--;
}
}
}
if (cleaf == null || emptyLines <= 0)
{
break;
}
}
prevCommit = ancestor;
prevLeaf = cleaf;
}
for (int n = 0; n < lines.Length; n++)
{
if (lines[n] == null)
{
lines[n] = CreateViewModel(GetLine(commit.Encoding, curText, n), prevAncestor);
}
}
return(lines);
}
public Commit[] Blame(string path)
{
Leaf leaf = Tree [path] as Leaf;
if (leaf == null)
{
throw new ArgumentException("The given path does not exist in this commit: " + path);
}
byte[] data = leaf.RawData;
int lineCount = RawParseUtils.lineMap(data, 0, data.Length).size();
Commit[] lines = new Commit [lineCount];
var curText = new RawText(data);
Commit prevAncestor = this;
Leaf prevLeaf = null;
Commit prevCommit = null;
int emptyLines = lineCount;
foreach (Commit ancestor in Ancestors)
{
Leaf cleaf = ancestor.Tree [path] as Leaf;
if (prevCommit != null && (cleaf == null || cleaf.Hash != prevLeaf.Hash))
{
byte[] prevData = prevLeaf.RawData;
if (prevData == null)
{
break;
}
var prevText = new RawText(prevData);
var differ = new MyersDiff(prevText, curText);
foreach (Edit e in differ.getEdits())
{
for (int n = e.BeginB; n < e.EndB; n++)
{
if (lines [n] == null)
{
lines [n] = prevCommit;
emptyLines--;
}
}
}
if (cleaf == null || emptyLines <= 0)
{
break;
}
}
prevCommit = ancestor;
prevLeaf = cleaf;
}
for (int n = 0; n < lines.Length; n++)
{
if (lines [n] == null)
{
lines [n] = prevAncestor;
}
}
return(lines);
}
/// <summary>
/// Creates a line-based diff from the the given byte arrays.
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
public Diff(byte[] a, byte[] b)
{
m_sequence_a = new Text(a);
m_sequence_b = new Text(b);
var diff = new MyersDiff((RawText)m_sequence_a, (RawText)m_sequence_b); // <--- using the undocumented cast operator of Text
m_edits = diff.getEdits();
}
/// <summary>
/// Makes comparison of two collections of string lines
/// </summary>
/// <param name="listA">Lines sequence A</param>
/// <param name="listB">Lines sequence B</param>
/// <returns>Edit script to transform A to B</returns>
public EditScript Execute(IList <string> listA, IList <string> listB)
{
int[] hashA = HashStringList(listA);
int[] hashB = HashStringList(listB);
MyersDiff <int> diff = new MyersDiff <int>(hashA, hashB, _supportChangeEditType);
EditScript result = diff.Execute();
return(result);
}
public static IEnumerable<DiffEntry> CompareCommits (NGit.Repository repo, AnyObjectId reference, ObjectId compared)
{
var diff = new MyersDiff (repo);
var firstTree = new CanonicalTreeParser ();
firstTree.Reset (repo.NewObjectReader (), new RevWalk (repo).ParseTree (reference));
diff.SetNewTree (firstTree);
if (compared != ObjectId.ZeroId) {
var secondTree = new CanonicalTreeParser ();
secondTree.Reset (repo.NewObjectReader (), new RevWalk (repo).ParseTree (compared));
if (compared != ObjectId.ZeroId)
diff.SetOldTree (secondTree);
}
return diff.Call ();
}
/// <summary>
/// Builds an EditScript which patches the original data to the desired data and uses this to create the Patchup patch.
/// </summary>
/// <param name="from">The original byte data which the patch will be applied to.</param>
/// <param name="to">The desired byte data which will result after applying the patch to the original byte data.</param>
public void Build(byte[] from, byte[] to)
{
this.EditScript = MyersDiff.SingleThreaded(from, to);
}
/// <summary>
/// Does the three way merge between a common base and two sequences.
/// </summary>
/// <param name="base">base the common base sequence</param>
/// <param name="ours">ours the first sequence to be merged</param>
/// <param name="theirs">theirs the second sequence to be merged</param>
/// <returns>the resulting content</returns>
public static MergeResult merge(Sequence @base, Sequence ours,
Sequence theirs)
{
List <Sequence> sequences = new List <Sequence>(3);
sequences.Add(@base);
sequences.Add(ours);
sequences.Add(theirs);
MergeResult result = new MergeResult(sequences);
EditList oursEdits = new MyersDiff(@base, ours).getEdits();
IteratorBase <Edit> baseToOurs = oursEdits.iterator();
EditList theirsEdits = new MyersDiff(@base, theirs).getEdits();
IteratorBase <Edit> baseToTheirs = theirsEdits.iterator();
int current = 0; // points to the next line (first line is 0) of base
// which was not handled yet
Edit oursEdit = nextEdit(baseToOurs);
Edit theirsEdit = nextEdit(baseToTheirs);
// iterate over all edits from base to ours and from base to theirs
// leave the loop when there are no edits more for ours or for theirs
// (or both)
while (theirsEdit != END_EDIT || oursEdit != END_EDIT)
{
if (oursEdit.EndA <= theirsEdit.BeginA)
{
// something was changed in ours not overlapping with any change
// from theirs. First add the common part in front of the edit
// then the edit.
if (current != oursEdit.BeginA)
{
result.add(0, current, oursEdit.BeginA,
MergeChunk.ConflictState.NO_CONFLICT);
}
result.add(1, oursEdit.BeginB, oursEdit.EndB,
MergeChunk.ConflictState.NO_CONFLICT);
current = oursEdit.EndA;
oursEdit = nextEdit(baseToOurs);
}
else if (theirsEdit.EndA <= oursEdit.BeginA)
{
// something was changed in theirs not overlapping with any
// from ours. First add the common part in front of the edit
// then the edit.
if (current != theirsEdit.BeginA)
{
result.add(0, current, theirsEdit.BeginA,
MergeChunk.ConflictState.NO_CONFLICT);
}
result.add(2, theirsEdit.BeginB, theirsEdit.EndB,
MergeChunk.ConflictState.NO_CONFLICT);
current = theirsEdit.EndA;
theirsEdit = nextEdit(baseToTheirs);
}
else
{
// here we found a real overlapping modification
// if there is a common part in front of the conflict add it
if (oursEdit.BeginA != current &&
theirsEdit.BeginA != current)
{
result.add(0, current, Math.Min(oursEdit.BeginA,
theirsEdit.BeginA), MergeChunk.ConflictState.NO_CONFLICT);
}
// set some initial values for the ranges in A and B which we
// want to handle
int oursBeginB = oursEdit.BeginB;
int theirsBeginB = theirsEdit.BeginB;
// harmonize the start of the ranges in A and B
if (oursEdit.BeginA < theirsEdit.BeginA)
{
theirsBeginB -= theirsEdit.BeginA
- oursEdit.BeginA;
}
else
{
oursBeginB -= oursEdit.BeginA - theirsEdit.BeginA;
}
// combine edits:
// Maybe an Edit on one side corresponds to multiple Edits on
// the other side. Then we have to combine the Edits of the
// other side - so in the end we can merge together two single
// edits.
//
// It is important to notice that this combining will extend the
// ranges of our conflict always downwards (towards the end of
// the content). The starts of the conflicting ranges in ours
// and theirs are not touched here.
//
// This combining is an iterative process: after we have
// combined some edits we have to do the check again. The
// combined edits could now correspond to multiple edits on the
// other side.
//
// Example: when this combining algorithm works on the following
// edits
// oursEdits=((0-5,0-5),(6-8,6-8),(10-11,10-11)) and
// theirsEdits=((0-1,0-1),(2-3,2-3),(5-7,5-7))
// it will merge them into
// oursEdits=((0-8,0-8),(10-11,10-11)) and
// theirsEdits=((0-7,0-7))
//
// Since the only interesting thing to us is how in ours and
// theirs the end of the conflicting range is changing we let
// oursEdit and theirsEdit point to the last conflicting edit
Edit nextOursEdit = nextEdit(baseToOurs);
Edit nextTheirsEdit = nextEdit(baseToTheirs);
for (; ;)
{
if (oursEdit.EndA > nextTheirsEdit.BeginA)
{
theirsEdit = nextTheirsEdit;
nextTheirsEdit = nextEdit(baseToTheirs);
}
else if (theirsEdit.EndA > nextOursEdit.BeginA)
{
oursEdit = nextOursEdit;
nextOursEdit = nextEdit(baseToOurs);
}
else
{
break;
}
}
// harmonize the end of the ranges in A and B
int oursEndB = oursEdit.EndB;
int theirsEndB = theirsEdit.EndB;
if (oursEdit.EndA < theirsEdit.EndA)
{
oursEndB += theirsEdit.EndA - oursEdit.EndA;
}
else
{
theirsEndB += oursEdit.EndA - theirsEdit.EndA;
}
// Add the conflict
result.add(1, oursBeginB, oursEndB,
MergeChunk.ConflictState.FIRST_CONFLICTING_RANGE);
result.add(2, theirsBeginB, theirsEndB,
MergeChunk.ConflictState.NEXT_CONFLICTING_RANGE);
current = Math.Max(oursEdit.EndA, theirsEdit.EndA);
oursEdit = nextOursEdit;
theirsEdit = nextTheirsEdit;
}
}
// maybe we have a common part behind the last edit: copy it to the
// result
if (current < @base.size())
{
result.add(0, current, @base.size(), MergeChunk.ConflictState.NO_CONFLICT);
}
return(result);
}
public void assertDiff(string a, string b, string edits)
{
MyersDiff diff = new MyersDiff(toCharArray(a), toCharArray(b));
Assert.AreEqual(edits, toString(diff.getEdits()));
}
