public string TestDiffWith(string text1, string text2, TextDivisions type, int expectedStart, int expectedLength)
{
var(start, length, difference) = text1.DiffWith(text2, type);
Assert.That(start, Is.EqualTo(expectedStart));
Assert.That(length, Is.EqualTo(expectedLength));
return(difference);
}
private static (int start, int length, string difference) LineDiff(string text1, string text2, TextDivisions type)
{
int start = -1, length = 0, s;
string diff = null;
(start, length, diff) = DiffElements(text1, text2, "\r\n");
if (start >= 0 && type != TextDivisions.Line)
{
(s, length, diff) = WordDiff(text1.Substring(start, length), text2.Substring(start), type);
start += s;
}
return(start, length, diff);
}
private static (int start, int length, string difference) WordDiff(string line1, string line2, TextDivisions type)
{
int start = -1, length, s;
string diff = null;
(start, length, diff) = DiffElements(line1, line2, " ");
if (start >= 0 && type != TextDivisions.Word)
{
(s, length, diff) = LetterDiff(line1.Substring(start, length), line2.Substring(start));
start += s;
}
return(start, length, diff);
}
/// <summary>
/// Determines the difference between the target instance and another string.
/// </summary>
/// <param name="target">The extension method target.</param>
/// <param name="other">The string to compare to.</param>
/// <param name="type">The type of comparison to perform.</param>
/// <returns>The start index and length within the target instance and the content from the comparison string that differs
/// from the target instance; or if no difference is found, an index of <c>-1</c>.</returns>
public static (int start, int length, string difference) DiffWith(this string target, string other, TextDivisions type = TextDivisions.Line)
{
if (target == null)
{
throw new NullReferenceException();
}
if (other == null)
{
throw new ArgumentNullException("other");
}
if (type == TextDivisions.Line || target.IndexOf('\n') >= 0)
{
return(LineDiff(target, other, type));
}
if (type == TextDivisions.Word || target.IndexOf(' ') >= 0)
{
return(WordDiff(target, other, type));
}
return(LetterDiff(target, other));
}
