/// <summary>
/// Find the difference in 2 text documents, comparing by textlines.
/// The algorithm itself is comparing 2 arrays of numbers so when comparing 2 text documents
/// each line is converted into a (hash) number. This hash-value is computed by storing all
/// textlines into a common hashtable so i can find dublicates in there, and generating a
/// new number each time a new textline is inserted.
/// </summary>
/// <param name="TextA">A-version of the text (usualy the old one)</param>
/// <param name="TextB">B-version of the text (usualy the new one)</param>
/// <param name="trimSpace">When set to true, all leading and trailing whitespace characters are stripped out before the comparation is done.</param>
/// <param name="ignoreSpace">When set to true, all whitespace characters are converted to a single space character before the comparation is done.</param>
/// <param name="ignoreCase">When set to true, all characters are converted to their lowercase equivivalence before the comparation is done.</param>
/// <returns>Returns a array of Items that describe the differences.</returns>
static Item[] DiffText(LineCollection a, LineCollection b, DiffOptions options)
{
// prepare the input-text and convert to comparable numbers.
Hashtable h = new Hashtable(a.Count + b.Count);
// The A-Version of the data (original data) to be compared.
DiffData DataA = new DiffData(DiffCodes(a, h, options));
// The B-Version of the data (modified data) to be compared.
DiffData DataB = new DiffData(DiffCodes(b, h, options));
h = null; // free up hashtable memory (maybe)
int MAX = DataA.Length + DataB.Length + 1;
/// vector for the (0,0) to (x,y) search
int[] DownVector = new int[2 * MAX + 2];
/// vector for the (u,v) to (N,M) search
int[] UpVector = new int[2 * MAX + 2];
LCS(DataA, 0, DataA.Length, DataB, 0, DataB.Length, DownVector, UpVector);
Optimize(DataA);
Optimize(DataB);
return CreateDiffs(DataA, DataB);
} // DiffText
} // Diff
/// <summary>
/// This function converts all textlines of the text into unique numbers for every unique textline
/// so further work can work only with simple numbers.
/// </summary>
/// <param name="aText">the input text</param>
/// <param name="h">This extern initialized hashtable is used for storing all ever used textlines.</param>
/// <param name="trimSpace">ignore leading and trailing space characters</param>
/// <returns>a array of integers.</returns>
private static int[] DiffCodes(LineCollection lines, Hashtable h, DiffOptions options)
{
// get all codes of the text
int lastUsedCode = h.Count;
int []codes = new int[lines.Count];
for (int i = 0; i < lines.Count; ++i)
{
string s = lines[i].Text;
if (options != null && options.IgnoreWhitespace)
{
s = Regex.Replace(s, "\\s+", " "); // TODO: optimization: faster blank removal.
}
if (options != null && options.IgnoreCase)
s = s.ToLower();
object aCode = h[s];
if (aCode == null)
{
lastUsedCode++;
h[s] = lastUsedCode;
codes[i] = lastUsedCode;
}
else
{
codes[i] = (int)aCode;
} // if
} // for
return codes;
} // DiffCodes
static public void Main(string[] args)
{
LineCollection l1 = new LineCollection();
l1.Open(args[0]);
LineCollection l2 = new LineCollection();
l2.Open(args[1]);
Item[] diffs = DiffText(l1, l2, null);
if (true)
{
int context = 3;
for (int i = 0; i < diffs.Length; ++i)
{
//Console.WriteLine(diffs[i]);
Console.WriteLine("@@ -{0},{1} +{2},{3} @@", diffs[i].StartA + 1, 99, diffs[i].StartB, 99);
int firstContext = diffs[i].StartA - context;
if (firstContext < 0)
firstContext = 0;
for (int line = firstContext; line < diffs[i].StartA; ++line)
{
Console.Write(" ");
Console.WriteLine(l1[line].Text);
}
for (int j = 0; j < diffs[i].DeletedA; ++j)
{
Console.Write("-");
Console.WriteLine(l1[diffs[i].StartA + j].Text);
}
for (int j = 0; j < diffs[i].InsertedB; ++j)
{
Console.Write("+");
Console.WriteLine(l2[diffs[i].StartB + j].Text);
}
}
}
else
{
for (int i = 0; i < diffs.Length; ++i)
{
Console.WriteLine(diffs[i]);
for (int j = 0; j < diffs[i].DeletedA; ++j)
{
Console.Write("< ");
Console.WriteLine(l1[diffs[i].StartA + j].Text);
}
Console.WriteLine("---");
for (int j = 0; j < diffs[i].InsertedB; ++j)
{
Console.Write("> ");
Console.WriteLine(l2[diffs[i].StartB + j].Text);
}
}
}
}