/// <summary>
/// Determine if the two diffs overlap
/// </summary>
/// <param name="diff1">One of the objects to test</param>
/// <param name="diff2">One of the objects to test</param>
/// <returns>true if the diffs overlap else false</returns>
public static bool Intersects(Diff diff1, Diff diff2)
{
var start1 = diff1.Ancestor.Span.Start;
var end1 = diff1.Ancestor.Span.End;
var start2 = diff2.Ancestor.Span.Start;
var end2 = diff2.Ancestor.Span.End;
//true if start of one is within start of the other (inclusive)
return (start2 <= start1 && start1 <= end2)
|| (start1 <= start2 && start2 <= end1);
}
/// <summary>
/// Generates Diff results for each change that occurred from the ancestor to the changed
/// </summary>
/// <param name="ancestor">
/// The abstract syntax tree that the changed version originated from
/// </param>
/// <param name="changed">The abstract syntax tree that resulted from changing the ancestor</param>
/// <returns>Changes between the ancestor and changed</returns>
public static IEnumerable<Diff> Compare(SyntaxTree ancestor, SyntaxTree changed)
{
var offset = 0; //Tracks differences in indexes moving through the changed syntax tree
foreach (var change in changed.GetChanges(ancestor))
{ //Assumes that this list is sorted by place in file
var origLength = change.Span.Length;
var offsetChange = (change.NewText.Length - origLength);
var chanStart = change.Span.Start + offset;
var chanLength = origLength + offsetChange;
offset += offsetChange;
var d = new Diff
{
Ancestor = SpanDetails.Create(change.Span, ancestor),
Changed = SpanDetails.Create(new TextSpan(chanStart, chanLength), changed)
};
yield return d;
}
}
/// <summary>
/// Determines if a single diff intersects with any number of other diffs
/// </summary>
/// <param name="diff">single diff that will be compared against many</param>
/// <param name="diffs">multiple diffs that will be compared against a single diff</param>
/// <returns>true if an intersection occurs else false</returns>
public static bool IntersectsAny(Diff diff, IEnumerable<Diff> diffs)
=> diffs.Any(d => Intersects(diff, d));