// PATCH FUNCTIONS
/**
* Increase the context until it is unique,
* but don't let the pattern expand beyond Match_MaxBits.
* @param patch The patch to grow.
* @param text Source text.
*/
protected void patch_addContext(Patch patch, string text)
{
if (text.Length == 0)
{
return;
}
string pattern = text.Substring(patch.start2, patch.length1);
int padding = 0;
// Look for the first and last matches of pattern in text. If two
// different matches are found, increase the pattern length.
while (text.IndexOf(pattern, StringComparison.Ordinal)
!= text.LastIndexOf(pattern, StringComparison.Ordinal)
&& pattern.Length < Match_MaxBits - Patch_Margin - Patch_Margin)
{
padding += Patch_Margin;
pattern = text.JavaSubstring(Math.Max(0, patch.start2 - padding),
Math.Min(text.Length, patch.start2 + patch.length1 + padding));
}
// Add one chunk for good luck.
padding += Patch_Margin;
// Add the prefix.
string prefix = text.JavaSubstring(Math.Max(0, patch.start2 - padding),
patch.start2);
if (prefix.Length != 0)
{
patch.diffs.Insert(0, new Diff(Operation.EQUAL, prefix));
}
// Add the suffix.
string suffix = text.JavaSubstring(patch.start2 + patch.length1,
Math.Min(text.Length, patch.start2 + patch.length1 + padding));
if (suffix.Length != 0)
{
patch.diffs.Add(new Diff(Operation.EQUAL, suffix));
}
// Roll back the start points.
patch.start1 -= prefix.Length;
patch.start2 -= prefix.Length;
// Extend the lengths.
patch.length1 += prefix.Length + suffix.Length;
patch.length2 += prefix.Length + suffix.Length;
}
/**
* Look through the patches and break up any which are longer than the
* maximum limit of the match algorithm.
* Intended to be called only from within patch_apply.
* @param patches List of Patch objects.
*/
public void patch_splitMax(List<Patch> patches)
{
short patch_size = this.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 = this.diff_text2(patch.diffs);
precontext = precontext.Substring(Math.Max(0,
precontext.Length - this.Patch_Margin));
string postcontext = null;
// Append the end context for this patch.
if (diff_text1(bigpatch.diffs).Length > Patch_Margin)
{
postcontext = diff_text1(bigpatch.diffs)
.Substring(0, Patch_Margin);
}
else
{
postcontext = diff_text1(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);
}
}
}
}
/**
* Parse a textual representation of patches and return a List of Patch
* objects.
* @param textline Text representation of patches.
* @return List of Patch objects.
* @throws ArgumentException If invalid input.
*/
public List<Patch> patch_fromText(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 = HttpUtility.UrlDecode(line, new UTF8Encoding(false, true));
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;
}
/**
* Compute a list of patches to turn text1 into text2.
* text2 is not provided, diffs are the delta between text1 and text2.
* @param text1 Old text.
* @param diffs Array of Diff objects for text1 to text2.
* @return List of Patch objects.
*/
public List<Patch> patch_make(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)
{
patch_addContext(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)
{
patch_addContext(patch, prepatch_text);
patches.Add(patch);
}
return patches;
}
/**
* Given an array of patches, return another array that is identical.
* @param patches Array of Patch objects.
* @return Array of Patch objects.
*/
public List<Patch> patch_deepCopy(List<Patch> patches)
{
List<Patch> patchesCopy = new List<Patch>();
foreach (Patch aPatch in patches)
{
Patch patchCopy = new Patch();
foreach (Diff aDiff in aPatch.diffs)
{
Diff diffCopy = new Diff(aDiff.operation, aDiff.text);
patchCopy.diffs.Add(diffCopy);
}
patchCopy.start1 = aPatch.start1;
patchCopy.start2 = aPatch.start2;
patchCopy.length1 = aPatch.length1;
patchCopy.length2 = aPatch.length2;
patchesCopy.Add(patchCopy);
}
return patchesCopy;
}
