高性能文本对比：diff-match-patch
2022/03
09
21:03
实现一个像Beyond Compare的工具，必然需要一个高性能的文本对比算法，Google已经实现了这个库，并且提供了各种语言版本
https://github.com/google/diff-match-patch/*
* Diff Match and Patch
* Copyright 2018 The diff-match-patch Authors.
* https://github.com/google/diff-match-patch
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;
namespace DiffMatchPatch
{
internal static class CompatibilityExtensions
{
// JScript splice function
public static List<T> Splice<T>(this List<T> input, int start, int count,
params T[] objects)
{
List<T> deletedRange = input.GetRange(start, count);
input.RemoveRange(start, count);
input.InsertRange(start, objects);
return deletedRange;
}
// Java substring function
public static string JavaSubstring(this string s, int begin, int end)
{
return s.Substring(begin, end - begin);
}
}
/**-
* The data structure representing a diff is a List of Diff objects:
* {Diff(Operation.DELETE, "Hello"), Diff(Operation.INSERT, "Goodbye"),
* Diff(Operation.EQUAL, " world.")}
* which means: delete "Hello", add "Goodbye" and keep " world."
*/
public enum Operation
{
DELETE, INSERT, EQUAL
}
/**
* Class representing one diff operation.
*/
public class Diff
{
public Operation operation;
// One of: INSERT, DELETE or EQUAL.
public string text;
// The text associated with this diff operation.
/**
* Constructor. Initializes the diff with the provided values.
* @param operation One of INSERT, DELETE or EQUAL.
* @param text The text being applied.
*/
public Diff(Operation operation, string text)
{
// Construct a diff with the specified operation and text.
this.operation = operation;
this.text = text;
}
/**
* Display a human-readable version of this Diff.
* @return text version.
*/
public override string ToString()
{
string prettyText = this.text.Replace('\n', '\u00b6');
return "Diff(" + this.operation + ",\"" + prettyText + "\")";
}
/**
* Is this Diff equivalent to another Diff?
* @param d Another Diff to compare against.
* @return true or false.
*/
public override bool Equals(Object obj)
{
// If parameter is null return false.
if (obj == null)
{
return false;
}
// If parameter cannot be cast to Diff return false.
Diff p = obj as Diff;
if ((System.Object)p == null)
{
return false;
}
// Return true if the fields match.
return p.operation == this.operation && p.text == this.text;
}
public bool Equals(Diff obj)
{
// If parameter is null return false.
if (obj == null)
{
return false;
}
// Return true if the fields match.
return obj.operation == this.operation && obj.text == this.text;
}
public override int GetHashCode()
{
return text.GetHashCode() ^ operation.GetHashCode();
}
}
/**
* Class representing one patch operation.
*/
public class Patch
{
public List<Diff> diffs = new List<Diff>();
public int start1;
public int start2;
public int length1;
public int length2;
/**
* Emulate GNU diff's format.
* Header: @@ -382,8 +481,9 @@
* Indices are printed as 1-based, not 0-based.
* @return The GNU diff string.
*/
public override string ToString()
{
string coords1, coords2;
if (this.length1 == 0)
{
coords1 = this.start1 + ",0";
}
else if (this.length1 == 1)
{
coords1 = Convert.ToString(this.start1 + 1);
}
else
{
coords1 = (this.start1 + 1) + "," + this.length1;
}
if (this.length2 == 0)
{
coords2 = this.start2 + ",0";
}
else if (this.length2 == 1)
{
coords2 = Convert.ToString(this.start2 + 1);
}
else
{
coords2 = (this.start2 + 1) + "," + this.length2;
}
StringBuilder text = new StringBuilder();
text.Append("@@ -").Append(coords1).Append(" +").Append(coords2)
.Append(" @@\n");
// Escape the body of the patch with %xx notation.
foreach (Diff aDiff in this.diffs)
{
switch (aDiff.operation)
{
case Operation.INSERT:
text.Append('+');
break;
case Operation.DELETE:
text.Append('-');
break;
case Operation.EQUAL:
text.Append(' ');
break;
}
text.Append(diff_match_patch.encodeURI(aDiff.text)).Append("\n");
}
return text.ToString();
}
}
/**
* Class containing the diff, match and patch methods.
* Also Contains the behaviour settings.
*/
public class diff_match_patch
{
// Defaults.
// Set these on your diff_match_patch instance to override the defaults.
// Number of seconds to map a diff before giving up (0 for infinity).
public float Diff_Timeout = 1.0f;
// Cost of an empty edit operation in terms of edit characters.
public short Diff_EditCost = 4;
// At what point is no match declared (0.0 = perfection, 1.0 = very loose).
public float Match_Threshold = 0.5f;
// How far to search for a match (0 = exact location, 1000+ = broad match).
// A match this many characters away from the expected location will add
// 1.0 to the score (0.0 is a perfect match).
public int Match_Distance = 1000;
// When deleting a large block of text (over ~64 characters), how close
// do the contents have to be to match the expected contents. (0.0 =
// perfection, 1.0 = very loose). Note that Match_Threshold controls
// how closely the end points of a delete need to match.
public float Patch_DeleteThreshold = 0.5f;
// Chunk size for context length.
public short Patch_Margin = 4;
// The number of bits in an int.
private short Match_MaxBits = 32;
// DIFF FUNCTIONS
/**
* Find the differences between two texts.
* Run a faster, slightly less optimal diff.
* This method allows the 'checklines' of diff_main() to be optional.
* Most of the time checklines is wanted, so default to true.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @return List of Diff objects.
*/
public List<Diff> diff_main(string text1, string text2)
{
return diff_main(text1, text2, true);
}
/**
* Find the differences between two texts.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @return List of Diff objects.
*/
public List<Diff> diff_main(string text1, string text2, bool checklines)
{
// Set a deadline by which time the diff must be complete.
DateTime deadline;
if (this.Diff_Timeout <= 0)
{
deadline = DateTime.MaxValue;
}
else
{
deadline = DateTime.Now +
new TimeSpan(((long)(Diff_Timeout * 1000)) * 10000);
}
return diff_main(text1, text2, checklines, deadline);
}
/**
* Find the differences between two texts. Simplifies the problem by
* stripping any common prefix or suffix off the texts before diffing.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @param deadline Time when the diff should be complete by. Used
* internally for recursive calls. Users should set DiffTimeout
* instead.
* @return List of Diff objects.
*/
private List<Diff> diff_main(string text1, string text2, bool checklines,
DateTime deadline)
{
// Check for null inputs not needed since null can't be passed in C#.
// Check for equality (speedup).
List<Diff> diffs;
if (text1 == text2)
{
diffs = new List<Diff>();
if (text1.Length != 0)
{
diffs.Add(new Diff(Operation.EQUAL, text1));
}
return diffs;
}
// Trim off common prefix (speedup).
int commonlength = diff_commonPrefix(text1, text2);
string commonprefix = text1.Substring(0, commonlength);
text1 = text1.Substring(commonlength);
text2 = text2.Substring(commonlength);
// Trim off common suffix (speedup).
commonlength = diff_commonSuffix(text1, text2);
string commonsuffix = text1.Substring(text1.Length - commonlength);
text1 = text1.Substring(0, text1.Length - commonlength);
text2 = text2.Substring(0, text2.Length - commonlength);
// Compute the diff on the middle block.
diffs = diff_compute(text1, text2, checklines, deadline);
// Restore the prefix and suffix.
if (commonprefix.Length != 0)
{
diffs.Insert(0, (new Diff(Operation.EQUAL, commonprefix)));
}
if (commonsuffix.Length != 0)
{
diffs.Add(new Diff(Operation.EQUAL, commonsuffix));
}
diff_cleanupMerge(diffs);
return diffs;
}
/**
* Find the differences between two texts. Assumes that the texts do not
* have any common prefix or suffix.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @param deadline Time when the diff should be complete by.
* @return List of Diff objects.
*/
private List<Diff> diff_compute(string text1, string text2,
bool checklines, DateTime deadline)
{
List<Diff> diffs = new List<Diff>();
if (text1.Length == 0)
{
// Just add some text (speedup).
diffs.Add(new Diff(Operation.INSERT, text2));
return diffs;
}
if (text2.Length == 0)
{
// Just delete some text (speedup).
diffs.Add(new Diff(Operation.DELETE, text1));
return diffs;
}
string longtext = text1.Length > text2.Length ? text1 : text2;
string shorttext = text1.Length > text2.Length ? text2 : text1;
int i = longtext.IndexOf(shorttext, StringComparison.Ordinal);
if (i != -1)
{
// Shorter text is inside the longer text (speedup).
Operation op = (text1.Length > text2.Length) ?
Operation.DELETE : Operation.INSERT;
diffs.Add(new Diff(op, longtext.Substring(0, i)));
diffs.Add(new Diff(Operation.EQUAL, shorttext));
diffs.Add(new Diff(op, longtext.Substring(i + shorttext.Length)));
return diffs;
}
if (shorttext.Length == 1)
{
// Single character string.
// After the previous speedup, the character can't be an equality.
diffs.Add(new Diff(Operation.DELETE, text1));
diffs.Add(new Diff(Operation.INSERT, text2));
return diffs;
}
// Check to see if the problem can be split in two.
string[] hm = diff_halfMatch(text1, text2);
if (hm != null)
{
// A half-match was found, sort out the return data.
string text1_a = hm[0];
string text1_b = hm[1];
string text2_a = hm[2];
string text2_b = hm[3];
string mid_common = hm[4];
// Send both pairs off for separate processing.
List<Diff> diffs_a = diff_main(text1_a, text2_a, checklines, deadline);
List<Diff> diffs_b = diff_main(text1_b, text2_b, checklines, deadline);
// Merge the results.
diffs = diffs_a;
diffs.Add(new Diff(Operation.EQUAL, mid_common));
diffs.AddRange(diffs_b);
return diffs;
}
if (checklines && text1.Length > 100 && text2.Length > 100)
{
return diff_lineMode(text1, text2, deadline);
}
return diff_bisect(text1, text2, deadline);
}
/**
* Do a quick line-level diff on both strings, then rediff the parts for
* greater accuracy.
* This speedup can produce non-minimal diffs.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param deadline Time when the diff should be complete by.
* @return List of Diff objects.
*/
private List<Diff> diff_lineMode(string text1, string text2,
DateTime deadline)
{
// Scan the text on a line-by-line basis first.
Object[] a = diff_linesToChars(text1, text2);
text1 = (string)a[0];
text2 = (string)a[1];
List<string> linearray = (List<string>)a[2];
List<Diff> diffs = diff_main(text1, text2, false, deadline);
// Convert the diff back to original text.
diff_charsToLines(diffs, linearray);
// Eliminate freak matches (e.g. blank lines)
diff_cleanupSemantic(diffs);
// Rediff any replacement blocks, this time character-by-character.
// Add a dummy entry at the end.
diffs.Add(new Diff(Operation.EQUAL, string.Empty));
int pointer = 0;
int count_delete = 0;
int count_insert = 0;
string text_delete = string.Empty;
string text_insert = string.Empty;
while (pointer < diffs.Count)
{
switch (diffs[pointer].operation)
{
case Operation.INSERT:
count_insert++;
text_insert += diffs[pointer].text;
break;
case Operation.DELETE:
count_delete++;
text_delete += diffs[pointer].text;
break;
case Operation.EQUAL:
// Upon reaching an equality, check for prior redundancies.
if (count_delete >= 1 && count_insert >= 1)
{
// Delete the offending records and add the merged ones.
diffs.RemoveRange(pointer - count_delete - count_insert,
count_delete + count_insert);
pointer = pointer - count_delete - count_insert;
List<Diff> subDiff =
this.diff_main(text_delete, text_insert, false, deadline);
diffs.InsertRange(pointer, subDiff);
pointer = pointer + subDiff.Count;
}
count_insert = 0;
count_delete = 0;
text_delete = string.Empty;
text_insert = string.Empty;
break;
}
pointer++;
}
diffs.RemoveAt(diffs.Count - 1); // Remove the dummy entry at the end.
return diffs;
}
/**
* Find the 'middle snake' of a diff, split the problem in two
* and return the recursively constructed diff.
* See Myers 1986 paper: An O(ND) Difference Algorithm and Its Variations.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param deadline Time at which to bail if not yet complete.
* @return List of Diff objects.
*/
protected List<Diff> diff_bisect(string text1, string text2,
DateTime deadline)
{
// Cache the text lengths to prevent multiple calls.
int text1_length = text1.Length;
int text2_length = text2.Length;
int max_d = (text1_length + text2_length + 1) / 2;
int v_offset = max_d;
int v_length = 2 * max_d;
int[] v1 = new int[v_length];
int[] v2 = new int[v_length];
for (int x = 0; x < v_length; x++)
{
v1[x] = -1;
v2[x] = -1;
}
v1[v_offset + 1] = 0;
v2[v_offset + 1] = 0;
int delta = text1_length - text2_length;
// If the total number of characters is odd, then the front path will
// collide with the reverse path.
bool front = (delta % 2 != 0);
// Offsets for start and end of k loop.
// Prevents mapping of space beyond the grid.
int k1start = 0;
int k1end = 0;
int k2start = 0;
int k2end = 0;
for (int d = 0; d < max_d; d++)
{
// Bail out if deadline is reached.
if (DateTime.Now > deadline)
{
break;
}
// Walk the front path one step.
for (int k1 = -d + k1start; k1 <= d - k1end; k1 += 2)
{
int k1_offset = v_offset + k1;
int x1;
if (k1 == -d || k1 != d && v1[k1_offset - 1] < v1[k1_offset + 1])
{
x1 = v1[k1_offset + 1];
}
else
{
x1 = v1[k1_offset - 1] + 1;
}
int y1 = x1 - k1;
while (x1 < text1_length && y1 < text2_length
&& text1[x1] == text2[y1])
{
x1++;
y1++;
}
v1[k1_offset] = x1;
if (x1 > text1_length)
{
// Ran off the right of the graph.
k1end += 2;
}
else if (y1 > text2_length)
{
// Ran off the bottom of the graph.
k1start += 2;
}
else if (front)
{
int k2_offset = v_offset + delta - k1;
if (k2_offset >= 0 && k2_offset < v_length && v2[k2_offset] != -1)
{
// Mirror x2 onto top-left coordinate system.
int x2 = text1_length - v2[k2_offset];
if (x1 >= x2)
{
// Overlap detected.
return diff_bisectSplit(text1, text2, x1, y1, deadline);
}
}
}
}
// Walk the reverse path one step.
for (int k2 = -d + k2start; k2 <= d - k2end; k2 += 2)
{
int k2_offset = v_offset + k2;
int x2;
if (k2 == -d || k2 != d && v2[k2_offset - 1] < v2[k2_offset + 1])
{
x2 = v2[k2_offset + 1];
}
else
{
x2 = v2[k2_offset - 1] + 1;
}
int y2 = x2 - k2;
while (x2 < text1_length && y2 < text2_length
&& text1[text1_length - x2 - 1]
== text2[text2_length - y2 - 1])
{
x2++;
y2++;
}
v2[k2_offset] = x2;
if (x2 > text1_length)
{
// Ran off the left of the graph.
k2end += 2;
}
else if (y2 > text2_length)
{
// Ran off the top of the graph.
k2start += 2;
}
else if (!front)
{
int k1_offset = v_offset + delta - k2;
if (k1_offset >= 0 && k1_offset < v_length && v1[k1_offset] != -1)
{
int x1 = v1[k1_offset];
int y1 = v_offset + x1 - k1_offset;
// Mirror x2 onto top-left coordinate system.
x2 = text1_length - v2[k2_offset];
if (x1 >= x2)
{
// Overlap detected.
return diff_bisectSplit(text1, text2, x1, y1, deadline);
}
}
}
}
}
// Diff took too long and hit the deadline or
// number of diffs equals number of characters, no commonality at all.
List<Diff> diffs = new List<Diff>();
diffs.Add(new Diff(Operation.DELETE, text1));
diffs.Add(new Diff(Operation.INSERT, text2));
return diffs;
}
/**
* Given the location of the 'middle snake', split the diff in two parts
* and recurse.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param x Index of split point in text1.
* @param y Index of split point in text2.
* @param deadline Time at which to bail if not yet complete.
* @return LinkedList of Diff objects.
*/
private List<Diff> diff_bisectSplit(string text1, string text2,
int x, int y, DateTime deadline)
{
string text1a = text1.Substring(0, x);
string text2a = text2.Substring(0, y);
string text1b = text1.Substring(x);
string text2b = text2.Substring(y);
// Compute both diffs serially.
List<Diff> diffs = diff_main(text1a, text2a, false, deadline);
List<Diff> diffsb = diff_main(text1b, text2b, false, deadline);
diffs.AddRange(diffsb);
return diffs;
}
/**
* Split two texts into a list of strings. Reduce the texts to a string of
* hashes where each Unicode character represents one line.
* @param text1 First string.
* @param text2 Second string.
* @return Three element Object array, containing the encoded text1, the
* encoded text2 and the List of unique strings. The zeroth element
* of the List of unique strings is intentionally blank.
*/
protected Object[] diff_linesToChars(string text1, string text2)
{
List<string> lineArray = new List<string>();
Dictionary<string, int> lineHash = new Dictionary<string, int>();
// e.g. linearray[4] == "Hello\n"
// e.g. linehash.get("Hello\n") == 4
// "\x00" is a valid character, but various debuggers don't like it.
// So we'll insert a junk entry to avoid generating a null character.
lineArray.Add(string.Empty);
// Allocate 2/3rds of the space for text1, the rest for text2.
string chars1 = diff_linesToCharsMunge(text1, lineArray, lineHash, 40000);
string chars2 = diff_linesToCharsMunge(text2, lineArray, lineHash, 65535);
return new Object[] { chars1, chars2, lineArray };
}
/**
* Split a text into a list of strings. Reduce the texts to a string of
* hashes where each Unicode character represents one line.
* @param text String to encode.
* @param lineArray List of unique strings.
* @param lineHash Map of strings to indices.
* @param maxLines Maximum length of lineArray.
* @return Encoded string.
*/
private string diff_linesToCharsMunge(string text, List<string> lineArray,
Dictionary<string, int> lineHash, int maxLines)
{
int lineStart = 0;
int lineEnd = -1;
string line;
StringBuilder chars = new StringBuilder();
// Walk the text, pulling out a Substring for each line.
// text.split('\n') would would temporarily double our memory footprint.
// Modifying text would create many large strings to garbage collect.
while (lineEnd < text.Length - 1)
{
lineEnd = text.IndexOf('\n', lineStart);
if (lineEnd == -1)
{
lineEnd = text.Length - 1;
}
line = text.JavaSubstring(lineStart, lineEnd + 1);
if (lineHash.ContainsKey(line))
{
chars.Append(((char)(int)lineHash[line]));
}
else
{
if (lineArray.Count == maxLines)
{
// Bail out at 65535 because char 65536 == char 0.
line = text.Substring(lineStart);
lineEnd = text.Length;
}
lineArray.Add(line);
lineHash.Add(line, lineArray.Count - 1);
chars.Append(((char)(lineArray.Count - 1)));
}
lineStart = lineEnd + 1;
}
return chars.ToString();
}
/**
* Rehydrate the text in a diff from a string of line hashes to real lines
* of text.
* @param diffs List of Diff objects.
* @param lineArray List of unique strings.
*/
protected void diff_charsToLines(ICollection<Diff> diffs,
IList<string> lineArray)
{
StringBuilder text;
foreach (Diff diff in diffs)
{
text = new StringBuilder();
for (int j = 0; j < diff.text.Length; j++)
{
text.Append(lineArray[diff.text[j]]);
}
diff.text = text.ToString();
}
}
/**
* Determine the common prefix of two strings.
* @param text1 First string.
* @param text2 Second string.
* @return The number of characters common to the start of each string.
*/
public int diff_commonPrefix(string text1, string text2)
{
// Performance analysis: https://neil.fraser.name/news/2007/10/09/
int n = Math.Min(text1.Length, text2.Length);
for (int i = 0; i < n; i++)
{
if (text1[i] != text2[i])
{
return i;
}
}
return n;
}
/**
* Determine the common suffix of two strings.
* @param text1 First string.
* @param text2 Second string.
* @return The number of characters common to the end of each string.
*/
public int diff_commonSuffix(string text1, string text2)
{
// Performance analysis: https://neil.fraser.name/news/2007/10/09/
int text1_length = text1.Length;
int text2_length = text2.Length;
int n = Math.Min(text1.Length, text2.Length);
for (int i = 1; i <= n; i++)
{
if (text1[text1_length - i] != text2[text2_length - i])
{
return i - 1;
}
}
return n;
}
/**
* Determine if the suffix of one string is the prefix of another.
* @param text1 First string.
* @param text2 Second string.
* @return The number of characters common to the end of the first
* string and the start of the second string.
*/
protected int diff_commonOverlap(string text1, string text2)
{
// Cache the text lengths to prevent multiple calls.
int text1_length = text1.Length;
int text2_length = text2.Length;
// Eliminate the null case.
if (text1_length == 0 || text2_length == 0)
{
return 0;
}
// Truncate the longer string.
if (text1_length > text2_length)
{
text1 = text1.Substring(text1_length - text2_length);
}
else if (text1_length < text2_length)
{
text2 = text2.Substring(0, text1_length);
}
int text_length = Math.Min(text1_length, text2_length);
// Quick check for the worst case.
if (text1 == text2)
{
return text_length;
}
// Start by looking for a single character match
// and increase length until no match is found.
// Performance analysis: https://neil.fraser.name/news/2010/11/04/
int best = 0;
int length = 1;
while (true)
{
string pattern = text1.Substring(text_length - length);
int found = text2.IndexOf(pattern, StringComparison.Ordinal);
if (found == -1)
{
return best;
}
length += found;
if (found == 0 || text1.Substring(text_length - length) ==
text2.Substring(0, length))
{
best = length;
length++;
}
}
}
/**
* Do the two texts share a Substring which is at least half the length of
* the longer text?
* This speedup can produce non-minimal diffs.
* @param text1 First string.
* @param text2 Second string.
* @return Five element String array, containing the prefix of text1, the
* suffix of text1, the prefix of text2, the suffix of text2 and the
* common middle. Or null if there was no match.
*/
protected string[] diff_halfMatch(string text1, string text2)
{
if (this.Diff_Timeout <= 0)
{
// Don't risk returning a non-optimal diff if we have unlimited time.
return null;
}
string longtext = text1.Length > text2.Length ? text1 : text2;
string shorttext = text1.Length > text2.Length ? text2 : text1;
if (longtext.Length < 4 || shorttext.Length * 2 < longtext.Length)
{
return null; // Pointless.
}
// First check if the second quarter is the seed for a half-match.
string[] hm1 = diff_halfMatchI(longtext, shorttext,
(longtext.Length + 3) / 4);
// Check again based on the third quarter.
string[] hm2 = diff_halfMatchI(longtext, shorttext,
(longtext.Length + 1) / 2);
string[] hm;
if (hm1 == null && hm2 == null)
{
return null;
}
else if (hm2 == null)
{
hm = hm1;
}
else if (hm1 == null)
{
hm = hm2;
}
else
{
// Both matched. Select the longest.
hm = hm1[4].Length > hm2[4].Length ? hm1 : hm2;
}
// A half-match was found, sort out the return data.
if (text1.Length > text2.Length)
{
return hm;
//return new string[]{hm[0], hm[1], hm[2], hm[3], hm[4]};
}
else
{
return new string[] { hm[2], hm[3], hm[0], hm[1], hm[4] };
}
}
/**
* Does a Substring of shorttext exist within longtext such that the
* Substring is at least half the length of longtext?
* @param longtext Longer string.
* @param shorttext Shorter string.
* @param i Start index of quarter length Substring within longtext.
* @return Five element string array, containing the prefix of longtext, the
* suffix of longtext, the prefix of shorttext, the suffix of shorttext
* and the common middle. Or null if there was no match.
*/
private string[] diff_halfMatchI(string longtext, string shorttext, int i)
{
// Start with a 1/4 length Substring at position i as a seed.
string seed = longtext.Substring(i, longtext.Length / 4);
int j = -1;
string best_common = string.Empty;
string best_longtext_a = string.Empty, best_longtext_b = string.Empty;
string best_shorttext_a = string.Empty, best_shorttext_b = string.Empty;
while (j < shorttext.Length && (j = shorttext.IndexOf(seed, j + 1,
StringComparison.Ordinal)) != -1)
{
int prefixLength = diff_commonPrefix(longtext.Substring(i),
shorttext.Substring(j));
int suffixLength = diff_commonSuffix(longtext.Substring(0, i),
shorttext.Substring(0, j));
if (best_common.Length < suffixLength + prefixLength)
{
best_common = shorttext.Substring(j - suffixLength, suffixLength)
+ shorttext.Substring(j, prefixLength);
best_longtext_a = longtext.Substring(0, i - suffixLength);
best_longtext_b = longtext.Substring(i + prefixLength);
best_shorttext_a = shorttext.Substring(0, j - suffixLength);
best_shorttext_b = shorttext.Substring(j + prefixLength);
}
}
if (best_common.Length * 2 >= longtext.Length)
{
return new string[]{best_longtext_a, best_longtext_b,
best_shorttext_a, best_shorttext_b, best_common};
}
else
{
return null;
}
}
/**
* Reduce the number of edits by eliminating semantically trivial
* equalities.
* @param diffs List of Diff objects.
*/
public void diff_cleanupSemantic(List<Diff> diffs)
{
bool changes = false;
// Stack of indices where equalities are found.
Stack<int> equalities = new Stack<int>();
// Always equal to equalities[equalitiesLength-1][1]
string lastEquality = null;
int pointer = 0; // Index of current position.
// Number of characters that changed prior to the equality.
int length_insertions1 = 0;
int length_deletions1 = 0;
// Number of characters that changed after the equality.
int length_insertions2 = 0;
int length_deletions2 = 0;
while (pointer < diffs.Count)
{
if (diffs[pointer].operation == Operation.EQUAL)
{ // Equality found.
equalities.Push(pointer);
length_insertions1 = length_insertions2;
length_deletions1 = length_deletions2;
length_insertions2 = 0;
length_deletions2 = 0;
lastEquality = diffs[pointer].text;
}
else
{ // an insertion or deletion
if (diffs[pointer].operation == Operation.INSERT)
{
length_insertions2 += diffs[pointer].text.Length;
}
else
{
length_deletions2 += diffs[pointer].text.Length;
}
// Eliminate an equality that is smaller or equal to the edits on both
// sides of it.
if (lastEquality != null && (lastEquality.Length
<= Math.Max(length_insertions1, length_deletions1))
&& (lastEquality.Length
<= Math.Max(length_insertions2, length_deletions2)))
{
// Duplicate record.
diffs.Insert(equalities.Peek(),
new Diff(Operation.DELETE, lastEquality));
// Change second copy to insert.
diffs[equalities.Peek() + 1].operation = Operation.INSERT;
// Throw away the equality we just deleted.
equalities.Pop();
if (equalities.Count > 0)
{
equalities.Pop();
}
pointer = equalities.Count > 0 ? equalities.Peek() : -1;
length_insertions1 = 0; // Reset the counters.
length_deletions1 = 0;
length_insertions2 = 0;
length_deletions2 = 0;
lastEquality = null;
changes = true;
}
}
pointer++;
}
// Normalize the diff.
if (changes)
{
diff_cleanupMerge(diffs);
}
diff_cleanupSemanticLossless(diffs);
// Find any overlaps between deletions and insertions.
// e.g: <del>abcxxx</del><ins>xxxdef</ins>
// -> <del>abc</del>xxx<ins>def</ins>
// e.g: <del>xxxabc</del><ins>defxxx</ins>
// -> <ins>def</ins>xxx<del>abc</del>
// Only extract an overlap if it is as big as the edit ahead or behind it.
pointer = 1;
while (pointer < diffs.Count)
{
if (diffs[pointer - 1].operation == Operation.DELETE &&
diffs[pointer].operation == Operation.INSERT)
{
string deletion = diffs[pointer - 1].text;
string insertion = diffs[pointer].text;
int overlap_length1 = diff_commonOverlap(deletion, insertion);
int overlap_length2 = diff_commonOverlap(insertion, deletion);
if (overlap_length1 >= overlap_length2)
{
if (overlap_length1 >= deletion.Length / 2.0 ||
overlap_length1 >= insertion.Length / 2.0)
{
// Overlap found.
// Insert an equality and trim the surrounding edits.
diffs.Insert(pointer, new Diff(Operation.EQUAL,
insertion.Substring(0, overlap_length1)));
diffs[pointer - 1].text =
deletion.Substring(0, deletion.Length - overlap_length1);
diffs[pointer + 1].text = insertion.Substring(overlap_length1);
pointer++;
}
}
else
{
if (overlap_length2 >= deletion.Length / 2.0 ||
overlap_length2 >= insertion.Length / 2.0)
{
// Reverse overlap found.
// Insert an equality and swap and trim the surrounding edits.
diffs.Insert(pointer, new Diff(Operation.EQUAL,
deletion.Substring(0, overlap_length2)));
diffs[pointer - 1].operation = Operation.INSERT;
diffs[pointer - 1].text =
insertion.Substring(0, insertion.Length - overlap_length2);
diffs[pointer + 1].operation = Operation.DELETE;
diffs[pointer + 1].text = deletion.Substring(overlap_length2);
pointer++;
}
}
pointer++;
}
pointer++;
}
}
/**
* Look for single edits surrounded on both sides by equalities
* which can be shifted sideways to align the edit to a word boundary.
* e.g: The c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
* @param diffs List of Diff objects.
*/
public void diff_cleanupSemanticLossless(List<Diff> diffs)
{
int pointer = 1;
// Intentionally ignore the first and last element (don't need checking).
while (pointer < diffs.Count - 1)
{
if (diffs[pointer - 1].operation == Operation.EQUAL &&
diffs[pointer + 1].operation == Operation.EQUAL)
{
// This is a single edit surrounded by equalities.
string equality1 = diffs[pointer - 1].text;
string edit = diffs[pointer].text;
string equality2 = diffs[pointer + 1].text;
// First, shift the edit as far left as possible.
int commonOffset = this.diff_commonSuffix(equality1, edit);
if (commonOffset > 0)
{
string commonString = edit.Substring(edit.Length - commonOffset);
equality1 = equality1.Substring(0, equality1.Length - commonOffset);
edit = commonString + edit.Substring(0, edit.Length - commonOffset);
equality2 = commonString + equality2;
}
// Second, step character by character right,
// looking for the best fit.
string bestEquality1 = equality1;
string bestEdit = edit;
string bestEquality2 = equality2;
int bestScore = diff_cleanupSemanticScore(equality1, edit) +
diff_cleanupSemanticScore(edit, equality2);
while (edit.Length != 0 && equality2.Length != 0
&& edit[0] == equality2[0])
{
equality1 += edit[0];
edit = edit.Substring(1) + equality2[0];
equality2 = equality2.Substring(1);
int score = diff_cleanupSemanticScore(equality1, edit) +
diff_cleanupSemanticScore(edit, equality2);
// The >= encourages trailing rather than leading whitespace on
// edits.
if (score >= bestScore)
{
bestScore = score;
bestEquality1 = equality1;
bestEdit = edit;
bestEquality2 = equality2;
}
}
if (diffs[pointer - 1].text != bestEquality1)
{
// We have an improvement, save it back to the diff.
if (bestEquality1.Length != 0)
{
diffs[pointer - 1].text = bestEquality1;
}
else
{
diffs.RemoveAt(pointer - 1);
pointer--;
}
diffs[pointer].text = bestEdit;
if (bestEquality2.Length != 0)
{
diffs[pointer + 1].text = bestEquality2;
}
else
{
diffs.RemoveAt(pointer + 1);
pointer--;
}
}
}
pointer++;
}
}
/**
* Given two strings, compute a score representing whether the internal
* boundary falls on logical boundaries.
* Scores range from 6 (best) to 0 (worst).
* @param one First string.
* @param two Second string.
* @return The score.
*/
private int diff_cleanupSemanticScore(string one, string two)
{
if (one.Length == 0 || two.Length == 0)
{
// Edges are the best.
return 6;
}
// Each port of this function behaves slightly differently due to
// subtle differences in each language's definition of things like
// 'whitespace'. Since this function's purpose is largely cosmetic,
// the choice has been made to use each language's native features
// rather than force total conformity.
char char1 = one[one.Length - 1];
char char2 = two[0];
bool nonAlphaNumeric1 = !Char.IsLetterOrDigit(char1);
bool nonAlphaNumeric2 = !Char.IsLetterOrDigit(char2);
bool whitespace1 = nonAlphaNumeric1 && Char.IsWhiteSpace(char1);
bool whitespace2 = nonAlphaNumeric2 && Char.IsWhiteSpace(char2);
bool lineBreak1 = whitespace1 && Char.IsControl(char1);
bool lineBreak2 = whitespace2 && Char.IsControl(char2);
bool blankLine1 = lineBreak1 && BLANKLINEEND.IsMatch(one);
bool blankLine2 = lineBreak2 && BLANKLINESTART.IsMatch(two);
if (blankLine1 || blankLine2)
{
// Five points for blank lines.
return 5;
}
else if (lineBreak1 || lineBreak2)
{
// Four points for line breaks.
return 4;
}
else if (nonAlphaNumeric1 && !whitespace1 && whitespace2)
{
// Three points for end of sentences.
return 3;
}
else if (whitespace1 || whitespace2)
{
// Two points for whitespace.
return 2;
}
else if (nonAlphaNumeric1 || nonAlphaNumeric2)
{
// One point for non-alphanumeric.
return 1;
}
return 0;
}
// Define some regex patterns for matching boundaries.
private Regex BLANKLINEEND = new Regex("\\n\\r?\\n\\Z");
private Regex BLANKLINESTART = new Regex("\\A\\r?\\n\\r?\\n");
/**
* Reduce the number of edits by eliminating operationally trivial
* equalities.
* @param diffs List of Diff objects.
*/
public void diff_cleanupEfficiency(List<Diff> diffs)
{
bool changes = false;
// Stack of indices where equalities are found.
Stack<int> equalities = new Stack<int>();
// Always equal to equalities[equalitiesLength-1][1]
string lastEquality = string.Empty;
int pointer = 0; // Index of current position.
// Is there an insertion operation before the last equality.
bool pre_ins = false;
// Is there a deletion operation before the last equality.
bool pre_del = false;
// Is there an insertion operation after the last equality.
bool post_ins = false;
// Is there a deletion operation after the last equality.
bool post_del = false;
while (pointer < diffs.Count)
{
if (diffs[pointer].operation == Operation.EQUAL)
{ // Equality found.
if (diffs[pointer].text.Length < this.Diff_EditCost
&& (post_ins || post_del))
{
// Candidate found.
equalities.Push(pointer);
pre_ins = post_ins;
pre_del = post_del;
lastEquality = diffs[pointer].text;
}
else
{
// Not a candidate, and can never become one.
equalities.Clear();
lastEquality = string.Empty;
}
post_ins = post_del = false;
}
else
{ // An insertion or deletion.
if (diffs[pointer].operation == Operation.DELETE)
{
post_del = true;
}
else
{
post_ins = true;
}
/*
* Five types to be split:
* <ins>A</ins><del>B</del>XY<ins>C</ins><del>D</del>
* <ins>A</ins>X<ins>C</ins><del>D</del>
* <ins>A</ins><del>B</del>X<ins>C</ins>
* <ins>A</del>X<ins>C</ins><del>D</del>
* <ins>A</ins><del>B</del>X<del>C</del>
*/
if ((lastEquality.Length != 0)
&& ((pre_ins && pre_del && post_ins && post_del)
|| ((lastEquality.Length < this.Diff_EditCost / 2)
&& ((pre_ins ? 1 : 0) + (pre_del ? 1 : 0) + (post_ins ? 1 : 0)
+ (post_del ? 1 : 0)) == 3)))
{
// Duplicate record.
diffs.Insert(equalities.Peek(),
new Diff(Operation.DELETE, lastEquality));
// Change second copy to insert.
diffs[equalities.Peek() + 1].operation = Operation.INSERT;
equalities.Pop(); // Throw away the equality we just deleted.
lastEquality = string.Empty;
if (pre_ins && pre_del)
{
// No changes made which could affect previous entry, keep going.
post_ins = post_del = true;
equalities.Clear();
}
else
{
if (equalities.Count > 0)
{
equalities.Pop();
}
pointer = equalities.Count > 0 ? equalities.Peek() : -1;
post_ins = post_del = false;
}
changes = true;
}
}
pointer++;
}
if (changes)
{
diff_cleanupMerge(diffs);
}
}
/**
* Reorder and merge like edit sections. Merge equalities.
* Any edit section can move as long as it doesn't cross an equality.
* @param diffs List of Diff objects.
*/
public void diff_cleanupMerge(List<Diff> diffs)
{
// Add a dummy entry at the end.
diffs.Add(new Diff(Operation.EQUAL, string.Empty));
int pointer = 0;
int count_delete = 0;
int count_insert = 0;
string text_delete = string.Empty;
string text_insert = string.Empty;
int commonlength;
while (pointer < diffs.Count)
{
switch (diffs[pointer].operation)
{
case Operation.INSERT:
count_insert++;
text_insert += diffs[pointer].text;
pointer++;
break;
case Operation.DELETE:
count_delete++;
text_delete += diffs[pointer].text;
pointer++;
break;
case Operation.EQUAL:
// Upon reaching an equality, check for prior redundancies.
if (count_delete + count_insert > 1)
{
if (count_delete != 0 && count_insert != 0)
{
// Factor out any common prefixies.
commonlength = this.diff_commonPrefix(text_insert, text_delete);
if (commonlength != 0)
{
if ((pointer - count_delete - count_insert) > 0 &&
diffs[pointer - count_delete - count_insert - 1].operation
== Operation.EQUAL)
{
diffs[pointer - count_delete - count_insert - 1].text
+= text_insert.Substring(0, commonlength);
}
else
{
diffs.Insert(0, new Diff(Operation.EQUAL,
text_insert.Substring(0, commonlength)));
pointer++;
}
text_insert = text_insert.Substring(commonlength);
text_delete = text_delete.Substring(commonlength);
}
// Factor out any common suffixies.
commonlength = this.diff_commonSuffix(text_insert, text_delete);
if (commonlength != 0)
{
diffs[pointer].text = text_insert.Substring(text_insert.Length
- commonlength) + diffs[pointer].text;
text_insert = text_insert.Substring(0, text_insert.Length
- commonlength);
text_delete = text_delete.Substring(0, text_delete.Length
- commonlength);
}
}
// Delete the offending records and add the merged ones.
pointer -= count_delete + count_insert;
diffs.Splice(pointer, count_delete + count_insert);
if (text_delete.Length != 0)
{
diffs.Splice(pointer, 0,
new Diff(Operation.DELETE, text_delete));
pointer++;
}
if (text_insert.Length != 0)
{
diffs.Splice(pointer, 0,
new Diff(Operation.INSERT, text_insert));
pointer++;
}
pointer++;
}
else if (pointer != 0
&& diffs[pointer - 1].operation == Operation.EQUAL)
{
// Merge this equality with the previous one.
diffs[pointer - 1].text += diffs[pointer].text;
diffs.RemoveAt(pointer);
}
else
{
pointer++;
}
count_insert = 0;
count_delete = 0;
text_delete = string.Empty;
text_insert = string.Empty;
break;
}
}
if (diffs[diffs.Count - 1].text.Length == 0)
{
diffs.RemoveAt(diffs.Count - 1); // Remove the dummy entry at the end.
}
// Second pass: look for single edits surrounded on both sides by
// equalities which can be shifted sideways to eliminate an equality.
// e.g: A<ins>BA</ins>C -> <ins>AB</ins>AC
bool changes = false;
pointer = 1;
// Intentionally ignore the first and last element (don't need checking).
while (pointer < (diffs.Count - 1))
{
if (diffs[pointer - 1].operation == Operation.EQUAL &&
diffs[pointer + 1].operation == Operation.EQUAL)
{
// This is a single edit surrounded by equalities.
if (diffs[pointer].text.EndsWith(diffs[pointer - 1].text,
StringComparison.Ordinal))
{
// Shift the edit over the previous equality.
diffs[pointer].text = diffs[pointer - 1].text +
diffs[pointer].text.Substring(0, diffs[pointer].text.Length -
diffs[pointer - 1].text.Length);
diffs[pointer + 1].text = diffs[pointer - 1].text
+ diffs[pointer + 1].text;
diffs.Splice(pointer - 1, 1);
changes = true;
}
else if (diffs[pointer].text.StartsWith(diffs[pointer + 1].text,
StringComparison.Ordinal))
{
// Shift the edit over the next equality.
diffs[pointer - 1].text += diffs[pointer + 1].text;
diffs[pointer].text =
diffs[pointer].text.Substring(diffs[pointer + 1].text.Length)
+ diffs[pointer + 1].text;
diffs.Splice(pointer + 1, 1);
changes = true;
}
}
pointer++;
}
// If shifts were made, the diff needs reordering and another shift sweep.
if (changes)
{
this.diff_cleanupMerge(diffs);
}
}
/**
* loc is a location in text1, compute and return the equivalent location in
* text2.
* e.g. "The cat" vs "The big cat", 1->1, 5->8
* @param diffs List of Diff objects.
* @param loc Location within text1.
* @return Location within text2.
*/
public int diff_xIndex(List<Diff> diffs, int loc)
{
int chars1 = 0;
int chars2 = 0;
int last_chars1 = 0;
int last_chars2 = 0;
Diff lastDiff = null;
foreach (Diff aDiff in diffs)
{
if (aDiff.operation != Operation.INSERT)
{
// Equality or deletion.
chars1 += aDiff.text.Length;
}
if (aDiff.operation != Operation.DELETE)
{
// Equality or insertion.
chars2 += aDiff.text.Length;
}
if (chars1 > loc)
{
// Overshot the location.
lastDiff = aDiff;
break;
}
last_chars1 = chars1;
last_chars2 = chars2;
}
if (lastDiff != null && lastDiff.operation == Operation.DELETE)
{
// The location was deleted.
return last_chars2;
}
// Add the remaining character length.
return last_chars2 + (loc - last_chars1);
}
/**
* Convert a Diff list into a pretty HTML report.
* @param diffs List of Diff objects.
* @return HTML representation.
*/
public string diff_prettyHtml(List<Diff> diffs)
{
StringBuilder html = new StringBuilder();
foreach (Diff aDiff in diffs)
{
string text = aDiff.text.Replace("&", "&").Replace("<", "<")
.Replace(">", ">").Replace("\n", "¶<br>");
switch (aDiff.operation)
{
case Operation.INSERT:
html.Append("<ins style=\"background:#e6ffe6;\">").Append(text)
.Append("</ins>");
break;
case Operation.DELETE:
html.Append("<del style=\"background:#ffe6e6;\">").Append(text)
.Append("</del>");
break;
case Operation.EQUAL:
html.Append("<span>").Append(text).Append("</span>");
break;
}
}
return html.ToString();
}
/**
* Compute and return the source text (all equalities and deletions).
* @param diffs List of Diff objects.
* @return Source text.
*/
public string diff_text1(List<Diff> diffs)
{
StringBuilder text = new StringBuilder();
foreach (Diff aDiff in diffs)
{
if (aDiff.operation != Operation.INSERT)
{
text.Append(aDiff.text);
}
}
return text.ToString();
}
/**
* Compute and return the destination text (all equalities and insertions).
* @param diffs List of Diff objects.
* @return Destination text.
*/
public string diff_text2(List<Diff> diffs)
{
StringBuilder text = new StringBuilder();
foreach (Diff aDiff in diffs)
{
if (aDiff.operation != Operation.DELETE)
{
text.Append(aDiff.text);
}
}
return text.ToString();
}
/**
* Compute the Levenshtein distance; the number of inserted, deleted or
* substituted characters.
* @param diffs List of Diff objects.
* @return Number of changes.
*/
public int diff_levenshtein(List<Diff> diffs)
{
int levenshtein = 0;
int insertions = 0;
int deletions = 0;
foreach (Diff aDiff in diffs)
{
switch (aDiff.operation)
{
case Operation.INSERT:
insertions += aDiff.text.Length;
break;
case Operation.DELETE:
deletions += aDiff.text.Length;
break;
case Operation.EQUAL:
// A deletion and an insertion is one substitution.
levenshtein += Math.Max(insertions, deletions);
insertions = 0;
deletions = 0;
break;
}
}
levenshtein += Math.Max(insertions, deletions);
return levenshtein;
}
/**
* Crush the diff into an encoded string which describes the operations
* required to transform text1 into text2.
* E.g. =3\t-2\t+ing -> Keep 3 chars, delete 2 chars, insert 'ing'.
* Operations are tab-separated. Inserted text is escaped using %xx
* notation.
* @param diffs Array of Diff objects.
* @return Delta text.
*/
public string diff_toDelta(List<Diff> diffs)
{
StringBuilder text = new StringBuilder();
foreach (Diff aDiff in diffs)
{
switch (aDiff.operation)
{
case Operation.INSERT:
text.Append("+").Append(encodeURI(aDiff.text)).Append("\t");
break;
case Operation.DELETE:
text.Append("-").Append(aDiff.text.Length).Append("\t");
break;
case Operation.EQUAL:
text.Append("=").Append(aDiff.text.Length).Append("\t");
break;
}
}
string delta = text.ToString();
if (delta.Length != 0)
{
// Strip off trailing tab character.
delta = delta.Substring(0, delta.Length - 1);
}
return delta;
}
/**
* Given the original text1, and an encoded string which describes the
* operations required to transform text1 into text2, compute the full diff.
* @param text1 Source string for the diff.
* @param delta Delta text.
* @return Array of Diff objects or null if invalid.
* @throws ArgumentException If invalid input.
*/
public List<Diff> diff_fromDelta(string text1, string delta)
{
List<Diff> diffs = new List<Diff>();
int pointer = 0; // Cursor in text1
string[] tokens = delta.Split(new string[] { "\t" },
StringSplitOptions.None);
foreach (string token in tokens)
{
if (token.Length == 0)
{
// Blank tokens are ok (from a trailing \t).
continue;
}
// Each token begins with a one character parameter which specifies the
// operation of this token (delete, insert, equality).
string param = token.Substring(1);
switch (token[0])
{
case '+':
// decode would change all "+" to " "
param = param.Replace("+", "%2b");
param = HttpUtility.UrlDecode(param);
//} catch (UnsupportedEncodingException e) {
// // Not likely on modern system.
// throw new Error("This system does not support UTF-8.", e);
//} catch (IllegalArgumentException e) {
// // Malformed URI sequence.
// throw new IllegalArgumentException(
// "Illegal escape in diff_fromDelta: " + param, e);
//}
diffs.Add(new Diff(Operation.INSERT, param));
break;
case '-':
// Fall through.
case '=':
int n;
try
{
n = Convert.ToInt32(param);
}
catch (FormatException e)
{
throw new ArgumentException(
"Invalid number in diff_fromDelta: " + param, e);
}
if (n < 0)
{
throw new ArgumentException(
"Negative number in diff_fromDelta: " + param);
}
string text;
try
{
text = text1.Substring(pointer, n);
pointer += n;
}
catch (ArgumentOutOfRangeException e)
{
throw new ArgumentException("Delta length (" + pointer
+ ") larger than source text length (" + text1.Length
+ ").", e);
}
if (token[0] == '=')
{
diffs.Add(new Diff(Operation.EQUAL, text));
}
else
{
diffs.Add(new Diff(Operation.DELETE, text));
}
break;
default:
// Anything else is an error.
throw new ArgumentException(
"Invalid diff operation in diff_fromDelta: " + token[0]);
}
}
if (pointer != text1.Length)
{
throw new ArgumentException("Delta length (" + pointer
+ ") smaller than source text length (" + text1.Length + ").");
}
return diffs;
}
// MATCH FUNCTIONS
/**
* Locate the best instance of 'pattern' in 'text' near 'loc'.
* Returns -1 if no match found.
* @param text The text to search.
* @param pattern The pattern to search for.
* @param loc The location to search around.
* @return Best match index or -1.
*/
public int match_main(string text, string pattern, int loc)
{
// Check for null inputs not needed since null can't be passed in C#.
loc = Math.Max(0, Math.Min(loc, text.Length));
if (text == pattern)
{
// Shortcut (potentially not guaranteed by the algorithm)
return 0;
}
else if (text.Length == 0)
{
// Nothing to match.
return -1;
}
else if (loc + pattern.Length <= text.Length
&& text.Substring(loc, pattern.Length) == pattern)
{
// Perfect match at the perfect spot! (Includes case of null pattern)
return loc;
}
else
{
// Do a fuzzy compare.
return match_bitap(text, pattern, loc);
}
}
/**
* Locate the best instance of 'pattern' in 'text' near 'loc' using the
* Bitap algorithm. Returns -1 if no match found.
* @param text The text to search.
* @param pattern The pattern to search for.
* @param loc The location to search around.
* @return Best match index or -1.
*/
protected int match_bitap(string text, string pattern, int loc)
{
// assert (Match_MaxBits == 0 || pattern.Length <= Match_MaxBits)
// : "Pattern too long for this application.";
// Initialise the alphabet.
Dictionary<char, int> s = match_alphabet(pattern);
// Highest score beyond which we give up.
double score_threshold = Match_Threshold;
// Is there a nearby exact match? (speedup)
int best_loc = text.IndexOf(pattern, loc, StringComparison.Ordinal);
if (best_loc != -1)
{
score_threshold = Math.Min(match_bitapScore(0, best_loc, loc,
pattern), score_threshold);
// What about in the other direction? (speedup)
best_loc = text.LastIndexOf(pattern,
Math.Min(loc + pattern.Length, text.Length),
StringComparison.Ordinal);
if (best_loc != -1)
{
score_threshold = Math.Min(match_bitapScore(0, best_loc, loc,
pattern), score_threshold);
}
}
// Initialise the bit arrays.
int matchmask = 1 << (pattern.Length - 1);
best_loc = -1;
int bin_min, bin_mid;
int bin_max = pattern.Length + text.Length;
// Empty initialization added to appease C# compiler.
int[] last_rd = new int[0];
for (int d = 0; d < pattern.Length; d++)
{
// Scan for the best match; each iteration allows for one more error.
// Run a binary search to determine how far from 'loc' we can stray at
// this error level.
bin_min = 0;
bin_mid = bin_max;
while (bin_min < bin_mid)
{
if (match_bitapScore(d, loc + bin_mid, loc, pattern)
<= score_threshold)
{
bin_min = bin_mid;
}
else
{
bin_max = bin_mid;
}
bin_mid = (bin_max - bin_min) / 2 + bin_min;
}
// Use the result from this iteration as the maximum for the next.
bin_max = bin_mid;
int start = Math.Max(1, loc - bin_mid + 1);
int finish = Math.Min(loc + bin_mid, text.Length) + pattern.Length;
int[] rd = new int[finish + 2];
rd[finish + 1] = (1 << d) - 1;
for (int j = finish; j >= start; j--)
{
int charMatch;
if (text.Length <= j - 1 || !s.ContainsKey(text[j - 1]))
{
// Out of range.
charMatch = 0;
}
else
{
charMatch = s[text[j - 1]];
}
if (d == 0)
{
// First pass: exact match.
rd[j] = ((rd[j + 1] << 1) | 1) & charMatch;
}
else
{
// Subsequent passes: fuzzy match.
rd[j] = ((rd[j + 1] << 1) | 1) & charMatch
| (((last_rd[j + 1] | last_rd[j]) << 1) | 1) | last_rd[j + 1];
}
if ((rd[j] & matchmask) != 0)
{
double score = match_bitapScore(d, j - 1, loc, pattern);
// This match will almost certainly be better than any existing
// match. But check anyway.
if (score <= score_threshold)
{
// Told you so.
score_threshold = score;
best_loc = j - 1;
if (best_loc > loc)
{
// When passing loc, don't exceed our current distance from loc.
start = Math.Max(1, 2 * loc - best_loc);
}
else
{
// Already passed loc, downhill from here on in.
break;
}
}
}
}
if (match_bitapScore(d + 1, loc, loc, pattern) > score_threshold)
{
// No hope for a (better) match at greater error levels.
break;
}
last_rd = rd;
}
return best_loc;
}
/**
* Compute and return the score for a match with e errors and x location.
* @param e Number of errors in match.
* @param x Location of match.
* @param loc Expected location of match.
* @param pattern Pattern being sought.
* @return Overall score for match (0.0 = good, 1.0 = bad).
*/
private double match_bitapScore(int e, int x, int loc, string pattern)
{
float accuracy = (float)e / pattern.Length;
int proximity = Math.Abs(loc - x);
if (Match_Distance == 0)
{
// Dodge divide by zero error.
return proximity == 0 ? accuracy : 1.0;
}
return accuracy + (proximity / (float)Match_Distance);
}
/**
* Initialise the alphabet for the Bitap algorithm.
* @param pattern The text to encode.
* @return Hash of character locations.
*/
protected Dictionary<char, int> match_alphabet(string pattern)
{
Dictionary<char, int> s = new Dictionary<char, int>();
char[] char_pattern = pattern.ToCharArray();
foreach (char c in char_pattern)
{
if (!s.ContainsKey(c))
{
s.Add(c, 0);
}
}
int i = 0;
foreach (char c in char_pattern)
{
int value = s[c] | (1 << (pattern.Length - i - 1));
s[c] = value;
i++;
}
return s;
}
// 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;
}
/**
* Compute a list of patches to turn text1 into text2.
* A set of diffs will be computed.
* @param text1 Old text.
* @param text2 New text.
* @return List of Patch objects.
*/
public List<Patch> patch_make(string text1, string text2)
{
// Check for null inputs not needed since null can't be passed in C#.
// No diffs provided, compute our own.
List<Diff> diffs = diff_main(text1, text2, true);
if (diffs.Count > 2)
{
diff_cleanupSemantic(diffs);
diff_cleanupEfficiency(diffs);
}
return patch_make(text1, diffs);
}
/**
* Compute a list of patches to turn text1 into text2.
* text1 will be derived from the provided diffs.
* @param diffs Array of Diff objects for text1 to text2.
* @return List of Patch objects.
*/
public List<Patch> patch_make(List<Diff> diffs)
{
// Check for null inputs not needed since null can't be passed in C#.
// No origin string provided, compute our own.
string text1 = diff_text1(diffs);
return patch_make(text1, diffs);
}
/**
* Compute a list of patches to turn text1 into text2.
* text2 is ignored, diffs are the delta between text1 and text2.
* @param text1 Old text
* @param text2 Ignored.
* @param diffs Array of Diff objects for text1 to text2.
* @return List of Patch objects.
* @deprecated Prefer patch_make(string text1, List<Diff> diffs).
*/
public List<Patch> patch_make(string text1, string text2,
List<Diff> diffs)
{
return patch_make(text1, diffs);
}
/**
* 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.
// https://github.com/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;
}
/**
* Merge a set of patches onto the text. Return a patched text, as well
* as an array of true/false values indicating which patches were applied.
* @param patches Array of Patch objects
* @param text Old text.
* @return Two element Object array, containing the new text and an array of
* bool values.
*/
public Object[] patch_apply(List<Patch> patches, string text)
{
if (patches.Count == 0)
{
return new Object[] { text, new bool[0] };
}
// Deep copy the patches so that no changes are made to originals.
patches = patch_deepCopy(patches);
string nullPadding = this.patch_addPadding(patches);
text = nullPadding + text + nullPadding;
patch_splitMax(patches);
int x = 0;
// delta keeps track of the offset between the expected and actual
// location of the previous patch. If there are patches expected at
// positions 10 and 20, but the first patch was found at 12, delta is 2
// and the second patch has an effective expected position of 22.
int delta = 0;
bool[] results = new bool[patches.Count];
foreach (Patch aPatch in patches)
{
int expected_loc = aPatch.start2 + delta;
string text1 = diff_text1(aPatch.diffs);
int start_loc;
int end_loc = -1;
if (text1.Length > this.Match_MaxBits)
{
// patch_splitMax will only provide an oversized pattern
// in the case of a monster delete.
start_loc = match_main(text,
text1.Substring(0, this.Match_MaxBits), expected_loc);
if (start_loc != -1)
{
end_loc = match_main(text,
text1.Substring(text1.Length - this.Match_MaxBits),
expected_loc + text1.Length - this.Match_MaxBits);
if (end_loc == -1 || start_loc >= end_loc)
{
// Can't find valid trailing context. Drop this patch.
start_loc = -1;
}
}
}
else
{
start_loc = this.match_main(text, text1, expected_loc);
}
if (start_loc == -1)
{
// No match found. :(
results[x] = false;
// Subtract the delta for this failed patch from subsequent patches.
delta -= aPatch.length2 - aPatch.length1;
}
else
{
// Found a match. :)
results[x] = true;
delta = start_loc - expected_loc;
string text2;
if (end_loc == -1)
{
text2 = text.JavaSubstring(start_loc,
Math.Min(start_loc + text1.Length, text.Length));
}
else
{
text2 = text.JavaSubstring(start_loc,
Math.Min(end_loc + this.Match_MaxBits, text.Length));
}
if (text1 == text2)
{
// Perfect match, just shove the Replacement text in.
text = text.Substring(0, start_loc) + diff_text2(aPatch.diffs)
+ text.Substring(start_loc + text1.Length);
}
else
{
// Imperfect match. Run a diff to get a framework of equivalent
// indices.
List<Diff> diffs = diff_main(text1, text2, false);
if (text1.Length > this.Match_MaxBits
&& this.diff_levenshtein(diffs) / (float)text1.Length
> this.Patch_DeleteThreshold)
{
// The end points match, but the content is unacceptably bad.
results[x] = false;
}
else
{
diff_cleanupSemanticLossless(diffs);
int index1 = 0;
foreach (Diff aDiff in aPatch.diffs)
{
if (aDiff.operation != Operation.EQUAL)
{
int index2 = diff_xIndex(diffs, index1);
if (aDiff.operation == Operation.INSERT)
{
// Insertion
text = text.Insert(start_loc + index2, aDiff.text);
}
else if (aDiff.operation == Operation.DELETE)
{
// Deletion
text = text.Remove(start_loc + index2, diff_xIndex(diffs,
index1 + aDiff.text.Length) - index2);
}
}
if (aDiff.operation != Operation.DELETE)
{
index1 += aDiff.text.Length;
}
}
}
}
}
x++;
}
// Strip the padding off.
text = text.Substring(nullPadding.Length, text.Length
- 2 * nullPadding.Length);
return new Object[] { text, results };
}
/**
* Add some padding on text start and end so that edges can match something.
* Intended to be called only from within patch_apply.
* @param patches Array of Patch objects.
* @return The padding string added to each side.
*/
public string patch_addPadding(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;
}
/**
* 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);
}
}
}
}
/**
* Take a list of patches and return a textual representation.
* @param patches List of Patch objects.
* @return Text representation of patches.
*/
public string patch_toText(List<Patch> patches)
{
StringBuilder text = new StringBuilder();
foreach (Patch aPatch in patches)
{
text.Append(aPatch);
}
return text.ToString();
}
/**
* 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);
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;
}
/**
* Encodes a string with URI-style % escaping.
* Compatible with JavaScript's encodeURI function.
*
* @param str The string to encode.
* @return The encoded string.
*/
public static string encodeURI(string str)
{
// C# is overzealous in the replacements. Walk back on a few.
return new StringBuilder(HttpUtility.UrlEncode(str))
.Replace('+', ' ').Replace("%20", " ").Replace("%21", "!")
.Replace("%2a", "*").Replace("%27", "'").Replace("%28", "(")
.Replace("%29", ")").Replace("%3b", ";").Replace("%2f", "/")
.Replace("%3f", "?").Replace("%3a", ":").Replace("%40", "@")
.Replace("%26", "&").Replace("%3d", "=").Replace("%2b", "+")
.Replace("%24", "$").Replace("%2c", ",").Replace("%23", "#")
.Replace("%7e", "~")
.ToString();
}
}
}测试代码：
// Copyright 2010 Google Inc.
// All Right Reserved.
/*
* To compile with Mono:
* mcs Speedtest.cs ../DiffMatchPatch.cs
* To run with Mono:
* mono Speedtest.exe
*/
using DiffMatchPatch;
using System;
using System.Collections.Generic;
public class Speedtest
{
public static void Main(string[] args)
{
string text1 = System.IO.File.ReadAllText("Speedtest1.txt");
string text2 = System.IO.File.ReadAllText("Speedtest2.txt");
diff_match_patch dmp = new diff_match_patch();
dmp.Diff_Timeout = 0;
// Execute one reverse diff as a warmup.
var d1 = dmp.diff_main(text2, text1);
GC.Collect();
GC.WaitForPendingFinalizers();
DateTime ms_start = DateTime.Now;
var d2 = dmp.diff_main(text1, text2);
DateTime ms_end = DateTime.Now;
Console.WriteLine("Elapsed time: " + (ms_end - ms_start));
}
}CopyRights: The Post by BY-NC-SA For Authorization，Original If Not Noted，Reprint Please Indicate From 老刘@开发笔记
Post Link: 高性能文本对比：diff-match-patch
Post Link: 高性能文本对比：diff-match-patch