/// <summary>
/// Method to apply a .diff file to a new Roslyn source file. A small amount of "fuzziness" is
/// accepted to take into account that the new file may have been updated in a new revision.
/// But the lines noted as unchanged and removed must not have been changed by the revision.
/// </summary>
private static void DoFuzzyPatch(string diffFileFilename, string newFileFilename)
{
// Read the two files into storage as lines of text
string[] diffLines = File.ReadAllLines(diffFileFilename);
NewFile newFile = new NewFile(File.ReadAllLines(newFileFilename));
// Check the "new" file has not already been updated once. (This assumes .cs files will
// have C# comments and/or identifier names that include "Yacks", and .csproj files will
// reference the YacksCore assembly.)
if (newFile.NewFileLines.Exists((string x) => x.Contains("Yacks")))
{
Console.WriteLine("File has already been updated once: " + newFileFilename);
return;
}
// Check first two lines in .diff file look like they should, "---" and "+++"
if (diffLines.Length < 3 || diffLines[0].Substring(0, 3) != "---" ||
diffLines[1].Substring(0, 3) != "+++")
{
DisplayErrorOrInfo("Corrupt .diff file, invalid prefix lines: " + diffFileFilename);
return;
}
int diffIndex = 2; // Current zero-based location in the .diff file
// Loop to process the "hunks" in the .diff file
while (true)
{
// Find and check the next "hunk" in the .diff file
DiffHunk diffHunk = GetNextDiffHunk(diffFileFilename, diffLines, ref diffIndex);
if (diffHunk == null)
{
return; // Error encountered
}
if (diffHunk.DiffLines == null)
{
break; // No more hunks in .diff file
}
// Try to find the location in the new file that matches this hunk
int newFileIndex = newFile.FindHunkLocation(diffHunk);
if (newFileIndex == -1)
{
DisplayErrorOrInfo("Unable to find location to apply .diff file 'hunk' at line " +
diffHunk.DiffLineIndex + " for file " + diffFileFilename);
return;
}
// Apply the .diff file "hunk"
newFile.ApplyHunk(diffHunk, newFileIndex);
}
// Processing was successful if we get to here. Write the result to the disk and display
// some info on the console.
WriteToDisk(newFileFilename, newFile.NewFileLines);
Console.WriteLine("File in new revision updated: " + newFileFilename);
Console.WriteLine(string.Format(CultureInfo.InvariantCulture,
" Lines removed = {0}, lines added = {1}, displacement = {2}.",
newFile.LinesRemoved, newFile.LinesAdded, newFile.DisplacementFactor));
}