/// <summary>
/// Generates the diff, one line of output at a time.
/// </summary>
/// <returns>
/// A collection of <see cref="AlignedDiffChange"/> objects, one for
/// each line in the first or second collection (sometimes one instance for a line
/// from both, when lines are equal or similar.)
/// </returns>
public IEnumerable <AlignedDiffChange> Generate()
{
int i1 = 0;
int i2 = 0;
foreach (Diff2Change section in Diff2.Compare <T>(_Collection1, _Collection2, _EqualityComparer))
{
if (section.Equal)
{
for (int index = 0; index < section.Length1; index++)
{
yield return(new AlignedDiffChange(ChangeType.Same, i1, i2));
i1++;
i2++;
}
}
else
{
bool deletePlusAdd = true;
if (section.Length1 > 0 && section.Length2 > 0)
{
AlignedDiffChange[] alignedChanges = TryAlignChanges(section, i1, i2);
if (alignedChanges.Length > 0)
{
deletePlusAdd = false;
foreach (var change in alignedChanges)
{
yield return(change);
}
i1 += section.Length1;
i2 += section.Length2;
}
}
if (deletePlusAdd)
{
for (int index = 0; index < section.Length1; index++)
{
yield return(new AlignedDiffChange(ChangeType.Deleted, i1, -1));
i1++;
}
for (int index = 0; index < section.Length2; index++)
{
yield return(new AlignedDiffChange(ChangeType.Added, -1, i2));
i2++;
}
}
}
}
}
/// <summary>
/// Compares the two collections and generate a diff.
/// </summary>
/// <typeparam name="T">Type of the element in the list</typeparam>
/// <param name="left">The first collection.</param>
/// <param name="right">The second collection.</param>
/// <param name="comparer">The comparer.</param>
/// <returns>An enumeration of <see cref="Diff2Change"/>.</returns>
public static IEnumerable <Diff2Change> Compare <T>(IList <T> left, IList <T> right, IEqualityComparer <T> comparer)
{
if (left == null)
{
throw new ArgumentNullException("left");
}
if (right == null)
{
throw new ArgumentNullException("right");
}
if (comparer == null)
{
throw new ArgumentNullException("comparer");
}
var diff = new Diff2 <T>(left, right, comparer);
return(diff.Generate());
}
/// <summary>
/// Does a similarity comparison between the two values and returns their
/// similarity, a value ranging from 0.0 to 1.0, where 0.0 means they're
/// completely different and 1.0 means they have the same value.
/// </summary>
/// <param name="value1">
/// The first value to compare.
/// </param>
/// <param name="value2">
/// The second value to compare.
/// </param>
/// <returns>
/// A value ranging from 0.0 to 1.0, where 0.0 means they're
/// completely different and 1.0 means they have the same value.
/// </returns>
public double Compare(string value1, string value2)
{
if (ReferenceEquals(value1, value2))
{
return(1.0);
}
value1 = (value1 ?? String.Empty);
value2 = (value2 ?? String.Empty);
if (value1.Length == 0 && value2.Length == 0)
{
return(1.0);
}
if (value1.Length == 0 || value2.Length == 0)
{
return(0.0);
}
int same = Diff2.Compare(value1.ToCharArray(), value2.ToCharArray()).Where(s => s.Equal).Sum(s => s.Length1);
return((same * 2.0) / (value1.Length + value2.Length + 0.0));
}
/// <summary>
/// Determines if the two values are similar enough to align them
/// as a change, instead of not aligning them but reporting them
/// as a delete plus an add instead.
/// </summary>
/// <param name="value1">
/// The first value to compare against <paramref name="value2"/>.
/// </param>
/// <param name="value2">
/// The second value to compare against <paramref name="value1"/>.
/// </param>
/// <returns>
/// <c>true</c> if the two values are similar enough to report
/// them as a change; false if the two values aren't similar enough
/// but needs to be reported as a delete plus an add.
/// </returns>
public bool CanAlign(string value1, string value2)
{
if (ReferenceEquals(value1, value2))
{
return(true);
}
value1 = (value1 ?? String.Empty);
value2 = (value2 ?? String.Empty);
if (value1.Length == 0 && value2.Length == 0)
{
return(true);
}
if (value1.Length == 0 || value2.Length == 0)
{
return(false);
}
var diff = Diff2.Compare(value1.ToCharArray(), value2.ToCharArray());
return(_DiffPredicate(value1, value2, diff));
}
private List <Diff3Change> FixPreviousConflictAsMerge(List <Diff3Change> changes)
{
List <Diff3Change> toChanges = null;
for (int index = 0; index < changes.Count; index++)
{
var diff3 = changes[index];
if (diff3.ChangeType != Diff3ChangeType.Conflict)
{
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
continue;
}
if (!diff3.Base.IsValid && diff3.From1.IsValid && !diff3.From2.IsValid)
{
diff3.ChangeType = Diff3ChangeType.MergeFrom1;
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
else if (!diff3.Base.IsValid && !diff3.From1.IsValid && diff3.From2.IsValid)
{
diff3.ChangeType = Diff3ChangeType.MergeFrom2;
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
else if (diff3.Base.IsValid && diff3.From1.IsValid && !diff3.From2.IsValid)
{
if (IsRangeEqual(baseList, diff3.Base, modified1List, diff3.From1))
{
diff3.ChangeType = Diff3ChangeType.MergeFrom2;
}
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
else if (diff3.Base.IsValid && diff3.From2.IsValid && !diff3.From1.IsValid)
{
if (IsRangeEqual(baseList, diff3.Base, modified2List, diff3.From2))
{
diff3.ChangeType = Diff3ChangeType.MergeFrom1;
}
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
else if (diff3.From1.IsValid && diff3.From2.IsValid)
{
// If there is no base, we will try to merge 1 and 2 together directly
if (!diff3.Base.IsValid)
{
if (toChanges == null)
{
toChanges = new List <Diff3Change>(changes.Count);
for (int i = 0; i < index; i++)
{
toChanges.Add(changes[i]);
}
}
var from1Range = diff3.From1;
var from2Range = diff3.From2;
if (subList1 == null)
{
subList1 = new List <T>(Math.Max(10, from1Range.Length));
}
if (subList2 == null)
{
subList2 = new List <T>(Math.Max(10, from2Range.Length));
}
subList1.Clear();
subList2.Clear();
for (int i = from1Range.From; i <= from1Range.To; i++)
{
subList1.Add(modified1List[i]);
}
for (int i = from2Range.From; i <= from2Range.To; i++)
{
subList2.Add(modified2List[i]);
}
var diffModified1Modified2 = Diff2.Compare(subList1, subList2, comparer).ToList();
int diff1Index = from1Range.From;
int diff2Index = from2Range.From;
// Try to evaluate the base index to give an indication where the merge would be inserted in base
var baseIndex = index > 0 ? changes[index - 1].Base.IsValid ? changes[index - 1].Base.To + 1 : 0 : 0;
var spanBase = new Span(baseIndex, baseIndex);
foreach (var diff2Change in diffModified1Modified2)
{
if (diff2Change.Equal)
{
AddChangeType(toChanges, Diff3ChangeType.MergeFrom1And2, spanBase, new Span(diff1Index, diff1Index + diff2Change.Length1 - 1), new Span(diff2Index, diff2Index + diff2Change.Length2 - 1), null, null);
}
else if (diff2Change.Length1 == 0)
{
AddChangeType(toChanges, Diff3ChangeType.MergeFrom2, spanBase, Span.Invalid, new Span(diff2Index, diff2Index + diff2Change.Length2 - 1), null, null);
}
else if (diff2Change.Length2 == 0)
{
AddChangeType(toChanges, Diff3ChangeType.Conflict, spanBase, new Span(diff1Index, diff1Index + diff2Change.Length1 - 1), Span.Invalid, null, null);
}
else
{
AddChangeType(toChanges, Diff3ChangeType.Conflict, spanBase, new Span(diff1Index, diff1Index + diff2Change.Length1 - 1), new Span(diff2Index, diff2Index + diff2Change.Length2 - 1), null, null);
}
diff1Index += diff2Change.Length1;
diff2Index += diff2Change.Length2;
}
}
else
{
// if base = v1 then MergeFrom2
if (diff3.IsBaseEqualFrom1.HasValue && diff3.IsBaseEqualFrom1.Value)
{
diff3.ChangeType = Diff3ChangeType.MergeFrom2;
}
// if base = v2 then MergeFrom1
else if (diff3.IsBaseEqualFrom2.HasValue && diff3.IsBaseEqualFrom2.Value)
{
diff3.ChangeType = Diff3ChangeType.MergeFrom1;
}
else if (diff3.Base.Length == diff3.From1.Length && diff3.Base.Length == diff3.From2.Length)
{
// Else if have a base != v1 and base != v2
// Check that if v1 = v2 and range is same for (base,v1,v2) then
// this can be considered as a MergeFrom1And2
if (diff3.IsBaseEqualFrom1.HasValue && diff3.IsBaseEqualFrom1.Value && (!diff3.IsBaseEqualFrom2.HasValue || !diff3.IsBaseEqualFrom2.Value))
{
diff3.ChangeType = Diff3ChangeType.MergeFrom2;
}
else if (diff3.IsBaseEqualFrom2.HasValue && diff3.IsBaseEqualFrom2.Value && (!diff3.IsBaseEqualFrom1.HasValue || !diff3.IsBaseEqualFrom1.Value))
{
diff3.ChangeType = Diff3ChangeType.MergeFrom1;
}
else
{
bool isFrom1AndFrom2Equal = true;
for (int i = 0; i < diff3.Base.Length; i++)
{
if (!comparer.Equals(modified1List[diff3.From1.From + i], modified2List[diff3.From2.From + i]))
{
isFrom1AndFrom2Equal = false;
break;
}
}
if (isFrom1AndFrom2Equal)
{
diff3.ChangeType = Diff3ChangeType.MergeFrom1And2;
}
}
}
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
}
else
{
if (toChanges != null)
{
AddChangeType(toChanges, diff3);
}
}
}
return(toChanges ?? changes);
}
public List <Diff3Change> Generate()
{
var diffBaseModified1 = ConvertDiffChangeWithNoRange(Diff2.Compare(baseList, modified1List, comparer)).ToList();
var diffBaseModified2 = ConvertDiffChangeWithNoRange(Diff2.Compare(baseList, modified2List, comparer)).ToList();
var changes = new List <Diff3Change>();
int index1 = 0;
int index2 = 0;
int baseIndex1 = 0;
int baseIndex2 = 0;
int diffIndex1 = 0;
int diffIndex2 = 0;
while (diffIndex1 < diffBaseModified1.Count && diffIndex2 < diffBaseModified2.Count)
{
var diff1 = diffBaseModified1[diffIndex1];
var diff2 = diffBaseModified2[diffIndex2];
// If element1 and element2 are both equals to the base element
if (diff1.Equal && diff2.Equal && baseIndex1 == baseIndex2)
{
AddChangeType(changes, Diff3ChangeType.Equal, new Span(baseIndex1, baseIndex2), new Span(index1, index1 + diff1.Length2 - 1), new Span(index2, index2 + diff2.Length2 - 1), true, true);
baseIndex1 += diff1.Length1;
index1 += diff1.Length2;
baseIndex2 += diff2.Length1;
index2 += diff2.Length2;
diffIndex1++;
diffIndex2++;
}
else
{
var baseRange = Span.Invalid;
var from1Range = Span.Invalid;
var from2Range = Span.Invalid;
bool change1 = false;
bool change2 = false;
var diff1Equal = true;
var diff2Equal = true;
// Try to advance as much as possible on both sides until we reach a common point (baseIndex1 == baseIndex2)
// This will form a single conflict node
while (true)
{
if (diffIndex1 < diffBaseModified1.Count && !diff1.Equal || baseIndex2 > baseIndex1)
{
// Advance in list1
change1 = true;
diff1Equal &= diff1.Equal;
if (diff1.Length2 > 0)
{
from1Range = new Span(from1Range != Span.Invalid ? from1Range.From : index1, index1 + diff1.Length2 - 1);
}
if (diff1.Length1 > 0)
{
baseRange = new Span(baseRange != Span.Invalid ? baseRange.From : baseIndex1, baseIndex1 + diff1.Length1 - 1);
}
baseIndex1 += diff1.Length1;
index1 += diff1.Length2;
if (++diffIndex1 < diffBaseModified1.Count)
{
diff1 = diffBaseModified1[diffIndex1];
}
}
else if (diffIndex2 < diffBaseModified2.Count && !diff2.Equal || baseIndex1 > baseIndex2)
{
// Advance in list2
change2 = true;
diff2Equal &= diff2.Equal;
if (diff2.Length2 > 0)
{
from2Range = new Span(from2Range != Span.Invalid ? from2Range.From : index2, index2 + diff2.Length2 - 1);
}
if (diff2.Length1 > 0)
{
baseRange = new Span(baseRange != Span.Invalid ? baseRange.From : baseIndex2, baseIndex2 + diff2.Length1 - 1);
}
baseIndex2 += diff2.Length1;
index2 += diff2.Length2;
if (++diffIndex2 < diffBaseModified2.Count)
{
diff2 = diffBaseModified2[diffIndex2];
}
}
else
{
break;
}
}
AddChangeType(changes, Diff3ChangeType.Conflict, baseRange, from1Range, from2Range, change1 ? (bool?)diff1Equal : null, change2 ? (bool?)diff2Equal : null);
}
}
// Not sure this could happen, but in case, output conflicts instead of merge if original base-v1 and base-v2 diffs were not entirely processed
bool isInConflict = diffIndex1 < diffBaseModified1.Count && diffIndex2 < diffBaseModified2.Count;
// Process remaining diffs from1
while (diffIndex1 < diffBaseModified1.Count)
{
var diff1 = diffBaseModified1[diffIndex1];
AddChangeType(changes, isInConflict ? Diff3ChangeType.Conflict : Diff3ChangeType.MergeFrom1, new Span(baseIndex1, baseIndex1), new Span(index1, index1 + diff1.Length2 - 1), Span.Invalid, null, null);
baseIndex1 += diff1.Length1;
index1 += diff1.Length2;
diffIndex1++;
}
// Process remaining diffs from2
while (diffIndex2 < diffBaseModified2.Count)
{
var diff2 = diffBaseModified2[diffIndex2];
AddChangeType(changes, isInConflict ? Diff3ChangeType.Conflict : Diff3ChangeType.MergeFrom2, new Span(baseIndex2, baseIndex2), Span.Invalid, new Span(index2, index2 + diff2.Length2 - 1), null, null);
baseIndex2 += diff2.Length1;
index2 += diff2.Length2;
diffIndex2++;
}
return(FixPreviousConflictAsMerge(changes));
}