/// <summary>
/// Parse a textual representation of patches and return a List of Patch objects.
/// </summary>
/// <param name="textline">Text representation of patches.</param>
/// <returns>List of Patch objects.</returns>
/// <exception cref="ArgumentException">If invalid input.</exception>
public List <Patch> PatchFromText(string textline)
{
List <Patch> patches = new List <Patch>();
if (textline.Length == 0)
{
return(patches);
}
string[] text = textline.Split('\n');
int textPointer = 0;
Patch patch;
Regex patchHeader
= new Regex("^@@ -(\\d+),?(\\d*) \\+(\\d+),?(\\d*) @@$");
Match m;
char sign;
string line;
while (textPointer < text.Length)
{
m = patchHeader.Match(text[textPointer]);
if (!m.Success)
{
throw new ArgumentException("Invalid patch string: "
+ text[textPointer]);
}
patch = new Patch();
patches.Add(patch);
patch.start1 = Convert.ToInt32(m.Groups[1].Value);
if (m.Groups[2].Length == 0)
{
patch.start1--;
patch.length1 = 1;
}
else if (m.Groups[2].Value == "0")
{
patch.length1 = 0;
}
else
{
patch.start1--;
patch.length1 = Convert.ToInt32(m.Groups[2].Value);
}
patch.start2 = Convert.ToInt32(m.Groups[3].Value);
if (m.Groups[4].Length == 0)
{
patch.start2--;
patch.length2 = 1;
}
else if (m.Groups[4].Value == "0")
{
patch.length2 = 0;
}
else
{
patch.start2--;
patch.length2 = Convert.ToInt32(m.Groups[4].Value);
}
textPointer++;
while (textPointer < text.Length)
{
try
{
sign = text[textPointer][0];
}
catch (IndexOutOfRangeException)
{
// Blank line? Whatever.
textPointer++;
continue;
}
line = text[textPointer].Substring(1);
line = line.Replace("+", "%2b");
line = System.Net.WebUtility.UrlDecode(line);
if (sign == '-')
{
// Deletion.
patch.diffs.Add(new Diff(Operation.DELETE, line));
}
else if (sign == '+')
{
// Insertion.
patch.diffs.Add(new Diff(Operation.INSERT, line));
}
else if (sign == ' ')
{
// Minor equality.
patch.diffs.Add(new Diff(Operation.EQUAL, line));
}
else if (sign == '@')
{
// Start of next patch.
break;
}
else
{
// WTF?
throw new ArgumentException(
"Invalid patch mode '" + sign + "' in: " + line);
}
textPointer++;
}
}
return(patches);
}
/// <summary>
/// Add some padding on text start and end so that edges can match something.
/// </summary>
/// <remarks>Intended to be called only from within patch_apply.</remarks>
/// <param name="patches">Array of Patch objects.</param>
/// <returns>The padding string added to each side.</returns>
public string PatchAddPadding(List <Patch> patches)
{
short paddingLength = this.Patch_Margin;
string nullPadding = string.Empty;
for (short x = 1; x <= paddingLength; x++)
{
nullPadding += (char)x;
}
// Bump all the patches forward.
foreach (Patch aPatch in patches)
{
aPatch.start1 += paddingLength;
aPatch.start2 += paddingLength;
}
// Add some padding on start of first diff.
Patch patch = patches.First();
List <Diff> diffs = patch.diffs;
if (diffs.Count == 0 || diffs.First().operation != Operation.EQUAL)
{
// Add nullPadding equality.
diffs.Insert(0, new Diff(Operation.EQUAL, nullPadding));
patch.start1 -= paddingLength; // Should be 0.
patch.start2 -= paddingLength; // Should be 0.
patch.length1 += paddingLength;
patch.length2 += paddingLength;
}
else if (paddingLength > diffs.First().text.Length)
{
// Grow first equality.
Diff firstDiff = diffs.First();
int extraLength = paddingLength - firstDiff.text.Length;
firstDiff.text = nullPadding.Substring(firstDiff.text.Length)
+ firstDiff.text;
patch.start1 -= extraLength;
patch.start2 -= extraLength;
patch.length1 += extraLength;
patch.length2 += extraLength;
}
// Add some padding on end of last diff.
patch = patches.Last();
diffs = patch.diffs;
if (diffs.Count == 0 || diffs.Last().operation != Operation.EQUAL)
{
// Add nullPadding equality.
diffs.Add(new Diff(Operation.EQUAL, nullPadding));
patch.length1 += paddingLength;
patch.length2 += paddingLength;
}
else if (paddingLength > diffs.Last().text.Length)
{
// Grow last equality.
Diff lastDiff = diffs.Last();
int extraLength = paddingLength - lastDiff.text.Length;
lastDiff.text += nullPadding.Substring(0, extraLength);
patch.length1 += extraLength;
patch.length2 += extraLength;
}
return(nullPadding);
}
/// <summary>
/// Look through the patches and break up any which are longer than the
/// maximum limit of the match algorithm.
/// </summary>
/// <remarks>Intended to be called only from within patch_apply.</remarks>
/// <param name="patches">List of Patch objects.</param>
public void PatchSplitMax(List <Patch> patches)
{
short patch_size = Match.Match_MaxBits;
for (int x = 0; x < patches.Count; x++)
{
if (patches[x].length1 <= patch_size)
{
continue;
}
Patch bigpatch = patches[x];
// Remove the big old patch.
patches.Splice(x--, 1);
int start1 = bigpatch.start1;
int start2 = bigpatch.start2;
string precontext = string.Empty;
while (bigpatch.diffs.Count != 0)
{
// Create one of several smaller patches.
Patch patch = new Patch();
bool empty = true;
patch.start1 = start1 - precontext.Length;
patch.start2 = start2 - precontext.Length;
if (precontext.Length != 0)
{
patch.length1 = patch.length2 = precontext.Length;
patch.diffs.Add(new Diff(Operation.EQUAL, precontext));
}
while (bigpatch.diffs.Count != 0 &&
patch.length1 < patch_size - this.Patch_Margin)
{
Operation diff_type = bigpatch.diffs[0].operation;
string diff_text = bigpatch.diffs[0].text;
if (diff_type == Operation.INSERT)
{
// Insertions are harmless.
patch.length2 += diff_text.Length;
start2 += diff_text.Length;
patch.diffs.Add(bigpatch.diffs.First());
bigpatch.diffs.RemoveAt(0);
empty = false;
}
else if (diff_type == Operation.DELETE && patch.diffs.Count == 1 &&
patch.diffs.First().operation == Operation.EQUAL &&
diff_text.Length > 2 * patch_size)
{
// This is a large deletion. Let it pass in one chunk.
patch.length1 += diff_text.Length;
start1 += diff_text.Length;
empty = false;
patch.diffs.Add(new Diff(diff_type, diff_text));
bigpatch.diffs.RemoveAt(0);
}
else
{
// Deletion or equality. Only take as much as we can stomach.
diff_text = diff_text.Substring(0, Math.Min(diff_text.Length,
patch_size - patch.length1 - Patch_Margin));
patch.length1 += diff_text.Length;
start1 += diff_text.Length;
if (diff_type == Operation.EQUAL)
{
patch.length2 += diff_text.Length;
start2 += diff_text.Length;
}
else
{
empty = false;
}
patch.diffs.Add(new Diff(diff_type, diff_text));
if (diff_text == bigpatch.diffs[0].text)
{
bigpatch.diffs.RemoveAt(0);
}
else
{
bigpatch.diffs[0].text =
bigpatch.diffs[0].text.Substring(diff_text.Length);
}
}
}
// Compute the head context for the next patch.
precontext = DiffOps.GetText2(patch.diffs);
precontext = precontext.Substring(Math.Max(0,
precontext.Length - this.Patch_Margin));
string postcontext = null;
// Append the end context for this patch.
if (DiffOps.GetText1(bigpatch.diffs).Length > Patch_Margin)
{
postcontext = DiffOps.GetText1(bigpatch.diffs)
.Substring(0, Patch_Margin);
}
else
{
postcontext = DiffOps.GetText1(bigpatch.diffs);
}
if (postcontext.Length != 0)
{
patch.length1 += postcontext.Length;
patch.length2 += postcontext.Length;
if (patch.diffs.Count != 0 &&
patch.diffs[patch.diffs.Count - 1].operation
== Operation.EQUAL)
{
patch.diffs[patch.diffs.Count - 1].text += postcontext;
}
else
{
patch.diffs.Add(new Diff(Operation.EQUAL, postcontext));
}
}
if (!empty)
{
patches.Splice(++x, 0, patch);
}
}
}
}
/// <summary>
/// Compute a list of patches to turn text1 into text2.
/// text2 is not provided, diffs are the delta between text1 and text2.
/// </summary>
/// <param name="text1">Old text.</param>
/// <param name="diffs">Array of Diff objects for text1 to text2.</param>
/// <returns>List of Patch objects.</returns>
public List <Patch> PatchMake(string text1, List <Diff> diffs)
{
// Check for null inputs not needed since null can't be passed in C#.
List <Patch> patches = new List <Patch>();
if (diffs.Count == 0)
{
return(patches); // Get rid of the null case.
}
Patch patch = new Patch();
int char_count1 = 0; // Number of characters into the text1 string.
int char_count2 = 0; // Number of characters into the text2 string.
// Start with text1 (prepatch_text) and apply the diffs until we arrive at
// text2 (postpatch_text). We recreate the patches one by one to determine
// context info.
string prepatch_text = text1;
string postpatch_text = text1;
foreach (Diff aDiff in diffs)
{
if (patch.diffs.Count == 0 && aDiff.operation != Operation.EQUAL)
{
// A new patch starts here.
patch.start1 = char_count1;
patch.start2 = char_count2;
}
switch (aDiff.operation)
{
case Operation.INSERT:
patch.diffs.Add(aDiff);
patch.length2 += aDiff.text.Length;
postpatch_text = postpatch_text.Insert(char_count2, aDiff.text);
break;
case Operation.DELETE:
patch.length1 += aDiff.text.Length;
patch.diffs.Add(aDiff);
postpatch_text = postpatch_text.Remove(char_count2,
aDiff.text.Length);
break;
case Operation.EQUAL:
if (aDiff.text.Length <= 2 * Patch_Margin &&
patch.diffs.Count() != 0 && aDiff != diffs.Last())
{
// Small equality inside a patch.
patch.diffs.Add(aDiff);
patch.length1 += aDiff.text.Length;
patch.length2 += aDiff.text.Length;
}
if (aDiff.text.Length >= 2 * Patch_Margin)
{
// Time for a new patch.
if (patch.diffs.Count != 0)
{
PatchAaddContext(patch, prepatch_text);
patches.Add(patch);
patch = new Patch();
// Unlike Unidiff, our patch lists have a rolling context.
// http://code.google.com/p/google-diff-match-patch/wiki/Unidiff
// Update prepatch text & pos to reflect the application of the
// just completed patch.
prepatch_text = postpatch_text;
char_count1 = char_count2;
}
}
break;
}
// Update the current character count.
if (aDiff.operation != Operation.INSERT)
{
char_count1 += aDiff.text.Length;
}
if (aDiff.operation != Operation.DELETE)
{
char_count2 += aDiff.text.Length;
}
}
// Pick up the leftover patch if not empty.
if (patch.diffs.Count != 0)
{
PatchAaddContext(patch, prepatch_text);
patches.Add(patch);
}
return(patches);
}