DiffMatchPatch.java
/*******************************************************************************
* Copyhacked (H) 2012-2020.
* This program and the accompanying materials
* are made available under no term at all, use it like
* you want, but share and discuss about it
* every time possible with every body.
*
* Contributors:
* ron190 at ymail dot com - initial implementation
******************************************************************************/
package com.jsql.model.injection.strategy.blind.patch;
/**
* Diff Match and Patch
*
* Copyright 2006 Google Inc.
* http://code.google.com/p/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.
*/
import com.jsql.util.LogLevelUtil;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/*
* Functions for diff, match and patch.
* Computes the difference between two texts to create a patch.
* Applies the patch onto another text, allowing for errors.
*
* @author fraser@google.com (Neil Fraser)
*/
/**
* Class containing the diff, match and patch methods.
* Also contains the behaviour settings.
*/
public class DiffMatchPatch {
/**
* Log4j logger sent to view.
*/
private static final Logger LOGGER = LogManager.getRootLogger();
// 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 static final float DIFF_TIMEOUT = 1.0f;
/**
* Cost of an empty edit operation in terms of edit characters.
*/
public static final short DIFF_EDIT_COST = 4;
/**
* At what point is no match declared (0.0 = perfection, 1.0 = very loose).
*/
public static final 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 static final 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 static final float PATCH_DELETE_THRESHOLD = 0.5f;
/**
* Chunk size for context length.
*/
public static final short PATCH_MARGIN = 4;
/**
* The number of bits in an int.
*/
private static final short MATCH_MAX_BITS = 32;
// Define some regex patterns for matching boundaries.
private static final Pattern BLANK_LINE_END = Pattern.compile("\\n\\r?\\n\\Z", Pattern.DOTALL);
private static final Pattern BLANK_LINE_START = Pattern.compile("\\A\\r?\\n\\r?\\n", Pattern.DOTALL);
/**
* Internal class for returning results from diff_linesToChars().
* Other less paranoid languages just use a three-element array.
*/
protected static class LinesToCharsResult {
protected final String chars1;
protected final String chars2;
protected final List<String> lineArray;
protected LinesToCharsResult(String chars1, String chars2,
List<String> lineArray) {
this.chars1 = chars1;
this.chars2 = chars2;
this.lineArray = lineArray;
}
}
// DIFF FUNCTIONS
/**
* The data structure representing a diff is a Linked 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
}
/**
* 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 Linked List of Diff objects.
*/
public List<Diff> diffMain(String text1, String text2) {
return this.diffMain(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 Linked List of Diff objects.
*/
public LinkedList<Diff> diffMain(String text1, String text2, boolean checklines) {
// Set a deadline by which time the diff must be complete.
long deadline = System.currentTimeMillis() + (long) (DIFF_TIMEOUT * 1000);
return this.diffMain(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 valueText1 Old string to be diffed.
* @param valueText2 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 Linked List of Diff objects.
*/
private LinkedList<Diff> diffMain(String valueText1, String valueText2, boolean checklines, long deadline) {
String text1 = valueText1;
String text2 = valueText2;
// Check for null inputs.
if (text1 == null || text2 == null) {
throw new IllegalArgumentException("Null inputs. (diff_main)");
}
// Check for equality (speedup).
LinkedList<Diff> diffs;
if (text1.equals(text2)) {
diffs = new LinkedList<>();
if (!text1.isEmpty()) {
diffs.add(new Diff(Operation.EQUAL, text1));
}
return diffs;
}
// Trim off common prefix (speedup).
int commonlength = this.diffCommonPrefix(text1, text2);
String commonprefix = text1.substring(0, commonlength);
text1 = text1.substring(commonlength);
text2 = text2.substring(commonlength);
// Trim off common suffix (speedup).
commonlength = this.diffCommonSuffix(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 = this.diffCompute(text1, text2, checklines, deadline);
// Restore the prefix and suffix.
if (!commonprefix.isEmpty()) {
diffs.addFirst(new Diff(Operation.EQUAL, commonprefix));
}
if (!commonsuffix.isEmpty()) {
diffs.addLast(new Diff(Operation.EQUAL, commonsuffix));
}
this.diffCleanupMerge(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 Linked List of Diff objects.
*/
private LinkedList<Diff> diffCompute(String text1, String text2, boolean checklines, long deadline) {
LinkedList<Diff> diffs = new LinkedList<>();
if (text1.isEmpty()) {
// Just add some text (speedup).
diffs.add(new Diff(Operation.INSERT, text2));
return diffs;
}
if (text2.isEmpty()) {
// Just delete some text (speedup).
diffs.add(new Diff(Operation.DELETE, text1));
return diffs;
}
{
// New scope so as to garbage collect longtext and shorttext.
String longtext = text1.length() > text2.length() ? text1 : text2;
String shorttext = text1.length() > text2.length() ? text2 : text1;
int i = longtext.indexOf(shorttext);
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 = this.diffHalfMatch(text1, text2);
if (hm != null) {
// A half-match was found, sort out the return data.
String text1A = hm[0];
String text1B = hm[1];
String text2A = hm[2];
String text2B = hm[3];
String midCommon = hm[4];
// Send both pairs off for separate processing.
LinkedList<Diff> diffsA = this.diffMain(text1A, text2A, checklines, deadline);
List<Diff> diffsB = this.diffMain(text1B, text2B, checklines, deadline);
// Merge the results.
diffs = diffsA;
diffs.add(new Diff(Operation.EQUAL, midCommon));
diffs.addAll(diffsB);
return diffs;
}
if (checklines && text1.length() > 100 && text2.length() > 100) {
return this.diffLineMode(text1, text2, deadline);
}
return this.diffBisect(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 valueText1 Old string to be diffed.
* @param valueText2 New string to be diffed.
* @param deadline Time when the diff should be complete by.
* @return Linked List of Diff objects.
*/
private LinkedList<Diff> diffLineMode(String valueText1, String valueText2, long deadline) {
// Scan the text on a line-by-line basis first.
LinesToCharsResult b = this.diffLinesToChars(valueText1, valueText2);
String text1 = b.chars1;
String text2 = b.chars2;
List<String> linearray = b.lineArray;
LinkedList<Diff> diffs = this.diffMain(text1, text2, false, deadline);
// Convert the diff back to original text.
this.diffCharsToLines(diffs, linearray);
// Eliminate freak matches (e.g. blank lines)
this.diffCleanupSemantic(diffs);
// Rediff any replacement blocks, this time character-by-character.
// Add a dummy entry at the end.
diffs.add(new Diff(Operation.EQUAL, ""));
int countDelete = 0;
int countInsert = 0;
StringBuilder textDelete = new StringBuilder();
StringBuilder textInsert = new StringBuilder();
ListIterator<Diff> pointer = diffs.listIterator();
Diff thisDiff = pointer.next();
while (thisDiff != null) {
switch (thisDiff.getOperation()) {
case INSERT:
countInsert++;
textInsert.append(thisDiff.getText());
break;
case DELETE:
countDelete++;
textDelete.append(thisDiff.getText());
break;
case EQUAL:
// Upon reaching an equality, check for prior redundancies.
if (countDelete >= 1 && countInsert >= 1) {
// Delete the offending records and add the merged ones.
pointer.previous();
for (int j = 0; j < countDelete + countInsert; j++) {
pointer.previous();
pointer.remove();
}
for (Diff newDiff : this.diffMain(textDelete.toString(), textInsert.toString(), false, deadline)) {
pointer.add(newDiff);
}
}
countInsert = 0;
countDelete = 0;
textDelete.setLength(0);
textInsert.setLength(0);
break;
}
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
diffs.removeLast(); // 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 LinkedList of Diff objects.
*/
protected LinkedList<Diff> diffBisect(String text1, String text2, long deadline) {
// Cache the text lengths to prevent multiple calls.
int text1Length = text1.length();
int text2Length = text2.length();
int maxD = (text1Length + text2Length + 1) / 2;
int vOffset = maxD;
int vLength = 2 * maxD;
int[] v1 = new int[vLength];
int[] v2 = new int[vLength];
for (int x = 0; x < vLength; x++) {
v1[x] = -1;
v2[x] = -1;
}
v1[vOffset + 1] = 0;
v2[vOffset + 1] = 0;
int delta = text1Length - text2Length;
// If the total number of characters is odd, then the front path will
// collide with the reverse path.
boolean 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 < maxD; d++) {
// Bail out if deadline is reached.
if (System.currentTimeMillis() > deadline) {
break;
}
// Walk the front path one step.
for (int k1 = -d + k1start; k1 <= d - k1end; k1 += 2) {
int k1Offset = vOffset + k1;
int x1;
if (k1 == -d || (k1 != d && v1[k1Offset - 1] < v1[k1Offset + 1])) {
x1 = v1[k1Offset + 1];
} else {
x1 = v1[k1Offset - 1] + 1;
}
int y1 = x1 - k1;
while (x1 < text1Length && y1 < text2Length
&& text1.charAt(x1) == text2.charAt(y1)) {
x1++;
y1++;
}
v1[k1Offset] = x1;
if (x1 > text1Length) {
// Ran off the right of the graph.
k1end += 2;
} else if (y1 > text2Length) {
// Ran off the bottom of the graph.
k1start += 2;
} else if (front) {
int k2Offset = vOffset + delta - k1;
if (k2Offset >= 0 && k2Offset < vLength && v2[k2Offset] != -1) {
// Mirror x2 onto top-left coordinate system.
int x2 = text1Length - v2[k2Offset];
if (x1 >= x2) {
// Overlap detected.
return this.diffBisectSplit(text1, text2, x1, y1, deadline);
}
}
}
}
// Walk the reverse path one step.
for (int k2 = -d + k2start; k2 <= d - k2end; k2 += 2) {
int k2Offset = vOffset + k2;
int x2;
if (k2 == -d || (k2 != d && v2[k2Offset - 1] < v2[k2Offset + 1])) {
x2 = v2[k2Offset + 1];
} else {
x2 = v2[k2Offset - 1] + 1;
}
int y2 = x2 - k2;
while (x2 < text1Length && y2 < text2Length
&& text1.charAt(text1Length - x2 - 1)
== text2.charAt(text2Length - y2 - 1)) {
x2++;
y2++;
}
v2[k2Offset] = x2;
if (x2 > text1Length) {
// Ran off the left of the graph.
k2end += 2;
} else if (y2 > text2Length) {
// Ran off the top of the graph.
k2start += 2;
} else if (!front) {
int k1Offset = vOffset + delta - k2;
if (k1Offset >= 0 && k1Offset < vLength && v1[k1Offset] != -1) {
int x1 = v1[k1Offset];
int y1 = vOffset + x1 - k1Offset;
// Mirror x2 onto top-left coordinate system.
x2 = text1Length - x2;
if (x1 >= x2) {
// Overlap detected.
return this.diffBisectSplit(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.
LinkedList<Diff> diffs = new LinkedList<>();
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 LinkedList<Diff> diffBisectSplit(String text1, String text2, int x, int y, long 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.
LinkedList<Diff> diffs = this.diffMain(text1a, text2a, false, deadline);
List<Diff> diffsb = this.diffMain(text1b, text2b, false, deadline);
diffs.addAll(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 An object 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 LinesToCharsResult diffLinesToChars(String text1, String text2) {
List<String> lineArray = new ArrayList<>();
Map<String, Integer> lineHash = new HashMap<>();
// 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 chars1 = this.diffLinesToCharsMunge(text1, lineArray, lineHash);
String chars2 = this.diffLinesToCharsMunge(text2, lineArray, lineHash);
return new LinesToCharsResult(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.
* @return Encoded string.
*/
private String diffLinesToCharsMunge(String text, List<String> lineArray,
Map<String, Integer> lineHash) {
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.substring(lineStart, lineEnd + 1);
lineStart = lineEnd + 1;
if (lineHash.containsKey(line)) {
chars.append(String.valueOf((char) (int) lineHash.get(line)));
} else {
lineArray.add(line);
lineHash.put(line, lineArray.size() - 1);
chars.append(String.valueOf((char) (lineArray.size() - 1)));
}
}
return chars.toString();
}
/**
* Rehydrate the text in a diff from a string of line hashes to real lines of
* text.
* @param diffs LinkedList of Diff objects.
* @param lineArray List of unique strings.
*/
protected void diffCharsToLines(List<Diff> diffs, List<String> lineArray) {
StringBuilder text;
for (Diff diff : diffs) {
text = new StringBuilder();
for (int y = 0; y < diff.getText().length(); y++) {
text.append(lineArray.get(diff.getText().charAt(y)));
}
diff.setText(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 diffCommonPrefix(String text1, String text2) {
// Performance analysis: http://neil.fraser.name/news/2007/10/09/
int n = Math.min(text1.length(), text2.length());
for (int i = 0; i < n; i++) {
if (text1.charAt(i) != text2.charAt(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 diffCommonSuffix(String text1, String text2) {
// Performance analysis: http://neil.fraser.name/news/2007/10/09/
int text1Length = text1.length();
int text2Length = text2.length();
int n = Math.min(text1Length, text2Length);
for (int i = 1; i <= n; i++) {
if (text1.charAt(text1Length - i) != text2.charAt(text2Length - i)) {
return i - 1;
}
}
return n;
}
/**
* Determine if the suffix of one string is the prefix of another.
* @param valueText1 First string.
* @param valueText2 Second string.
* @return The number of characters common to the end of the first
* string and the start of the second string.
*/
protected int diffCommonOverlap(String valueText1, String valueText2) {
String text1 = valueText1;
String text2 = valueText2;
// Cache the text lengths to prevent multiple calls.
int text1Length = text1.length();
int text2Length = text2.length();
// Eliminate the null case.
if (text1Length == 0 || text2Length == 0) {
return 0;
}
// Truncate the longer string.
if (text1Length > text2Length) {
text1 = text1.substring(text1Length - text2Length);
} else if (text1Length < text2Length) {
text2 = text2.substring(0, text1Length);
}
int textLength = Math.min(text1Length, text2Length);
// Quick check for the worst case.
if (text1.equals(text2)) {
return textLength;
}
// Start by looking for a single character match
// and increase length until no match is found.
// Performance analysis: http://neil.fraser.name/news/2010/11/04/
int best = 0;
int length = 1;
while (true) {
String pattern = text1.substring(textLength - length);
int found = text2.indexOf(pattern);
if (found == -1) {
return best;
}
length += found;
if (found == 0 || text1.substring(textLength - length).equals(
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[] diffHalfMatch(String text1, String text2) {
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 = this.diffHalfMatchI(longtext, shorttext, (longtext.length() + 3) / 4);
// Check again based on the third quarter.
String[] hm2 = this.diffHalfMatchI(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;
} 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[] diffHalfMatchI(String longtext, String shorttext, int i) {
// Start with a 1/4 length substring at position i as a seed.
String seed = longtext.substring(i, i + longtext.length() / 4);
int j = -1;
String bestCommon = "";
String bestLongtextA = "";
String bestLongtextB = "";
String bestShorttextA = "";
String bestShorttextB = "";
while ((j = shorttext.indexOf(seed, j + 1)) != -1) {
int prefixLength = this.diffCommonPrefix(longtext.substring(i),
shorttext.substring(j));
int suffixLength = this.diffCommonSuffix(longtext.substring(0, i),
shorttext.substring(0, j));
if (bestCommon.length() < suffixLength + prefixLength) {
bestCommon = shorttext.substring(j - suffixLength, j)
+ shorttext.substring(j, j + prefixLength);
bestLongtextA = longtext.substring(0, i - suffixLength);
bestLongtextB = longtext.substring(i + prefixLength);
bestShorttextA = shorttext.substring(0, j - suffixLength);
bestShorttextB = shorttext.substring(j + prefixLength);
}
}
if (bestCommon.length() * 2 >= longtext.length()) {
return new String[]{bestLongtextA, bestLongtextB,
bestShorttextA, bestShorttextB, bestCommon};
} else {
return null;
}
}
/**
* Reduce the number of edits by eliminating semantically trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public void diffCleanupSemantic(LinkedList<Diff> diffs) {
if (diffs.isEmpty()) {
return;
}
boolean changes = false;
// Synchronized Stack to avoid Exception
Stack<Diff> equalities = new Stack<>(); // Stack of qualities.
String lastequality = null; // Always equal to equalities.lastElement().text
ListIterator<Diff> pointer = diffs.listIterator();
// Number of characters that changed prior to the equality.
int lengthInsertions1 = 0;
int lengthDeletions1 = 0;
// Number of characters that changed after the equality.
int lengthInsertions2 = 0;
int lengthDeletions2 = 0;
Diff thisDiff = pointer.next();
while (thisDiff != null) {
if (thisDiff.getOperation() == Operation.EQUAL) {
// Equality found.
equalities.push(thisDiff);
lengthInsertions1 = lengthInsertions2;
lengthDeletions1 = lengthDeletions2;
lengthInsertions2 = 0;
lengthDeletions2 = 0;
lastequality = thisDiff.getText();
} else {
// An insertion or deletion.
if (thisDiff.getOperation() == Operation.INSERT) {
lengthInsertions2 += thisDiff.getText().length();
} else {
lengthDeletions2 += thisDiff.getText().length();
}
// Eliminate an equality that is smaller or equal to the edits on both
// sides of it.
if (
lastequality != null
&& lastequality.length() <= Math.max(lengthInsertions1, lengthDeletions1)
&& lastequality.length() <= Math.max(lengthInsertions2, lengthDeletions2)
) {
// Walk back to offending equality.
while (thisDiff != equalities.lastElement()) {
thisDiff = pointer.previous();
}
pointer.next();
// Replace equality with a delete.
pointer.set(new Diff(Operation.DELETE, lastequality));
// Insert a corresponding an insert.
pointer.add(new Diff(Operation.INSERT, lastequality));
equalities.pop(); // Throw away the equality we just deleted.
if (!equalities.empty()) {
// Throw away the previous equality (it needs to be reevaluated).
equalities.pop();
}
if (equalities.empty()) {
// There are no previous equalities, walk back to the start.
while (pointer.hasPrevious()) {
pointer.previous();
}
} else {
// There is a safe equality we can fall back to.
thisDiff = equalities.lastElement();
while (thisDiff != pointer.previous()) {
// Intentionally empty loop.
}
}
lengthInsertions1 = 0; // Reset the counters.
lengthInsertions2 = 0;
lengthDeletions1 = 0;
lengthDeletions2 = 0;
lastequality = null;
changes = true;
}
}
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
// Normalize the diff.
if (changes) {
this.diffCleanupMerge(diffs);
}
this.diffCleanupSemanticLossless(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 = diffs.listIterator();
Diff prevDiff = null;
thisDiff = null;
if (pointer.hasNext()) {
prevDiff = pointer.next();
if (pointer.hasNext()) {
thisDiff = pointer.next();
}
}
while (thisDiff != null) {
if (prevDiff.getOperation() == Operation.DELETE &&
thisDiff.getOperation() == Operation.INSERT) {
String deletion = prevDiff.getText();
String insertion = thisDiff.getText();
int overlapLength1 = this.diffCommonOverlap(deletion, insertion);
int overlapLength2 = this.diffCommonOverlap(insertion, deletion);
if (overlapLength1 >= overlapLength2) {
if (overlapLength1 >= deletion.length() / 2.0 ||
overlapLength1 >= insertion.length() / 2.0) {
// Overlap found. Insert an equality and trim the surrounding edits.
pointer.previous();
pointer.add(new Diff(Operation.EQUAL,
insertion.substring(0, overlapLength1)));
prevDiff.setText(deletion.substring(0, deletion.length() - overlapLength1));
thisDiff.setText(insertion.substring(overlapLength1));
// pointer.add inserts the element before the cursor, so there is
// no need to step past the new element.
}
} else {
if (overlapLength2 >= deletion.length() / 2.0 ||
overlapLength2 >= insertion.length() / 2.0) {
// Reverse overlap found.
// Insert an equality and swap and trim the surrounding edits.
pointer.previous();
pointer.add(new Diff(Operation.EQUAL,
deletion.substring(0, overlapLength2)));
prevDiff.setOperation(Operation.INSERT);
prevDiff.setText(insertion.substring(0, insertion.length() - overlapLength2));
thisDiff.setOperation(Operation.DELETE);
thisDiff.setText(deletion.substring(overlapLength2));
// pointer.add inserts the element before the cursor, so there is
// no need to step past the new element.
}
}
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
prevDiff = thisDiff;
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
}
/**
* 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 LinkedList of Diff objects.
*/
public void diffCleanupSemanticLossless(List<Diff> diffs) {
StringBuilder equality1 = new StringBuilder();
String edit;
StringBuilder equality2 = new StringBuilder();
String commonString;
int commonOffset;
int score;
int bestScore;
String bestEquality1;
String bestEdit;
String bestEquality2;
// Create a new iterator at the start.
ListIterator<Diff> pointer = diffs.listIterator();
Diff prevDiff = pointer.hasNext() ? pointer.next() : null;
Diff thisDiff = pointer.hasNext() ? pointer.next() : null;
Diff nextDiff = pointer.hasNext() ? pointer.next() : null;
// Intentionally ignore the first and last element (don't need checking).
while (nextDiff != null) {
if (prevDiff.getOperation() == Operation.EQUAL &&
nextDiff.getOperation() == Operation.EQUAL) {
// This is a single edit surrounded by equalities.
equality1.setLength(0);
equality1.append(prevDiff.getText());
edit = thisDiff.getText();
equality2.setLength(0);
equality2.append(nextDiff.getText());
// First, shift the edit as far left as possible.
commonOffset = this.diffCommonSuffix(equality1.toString(), edit);
if (commonOffset != 0) {
commonString = edit.substring(edit.length() - commonOffset);
String substring = equality1.substring(0, equality1.length() - commonOffset);
equality1.setLength(0);
equality1.append(substring);
edit = commonString + edit.substring(0, edit.length() - commonOffset);
equality2.insert(0, commonString);
}
// Second, step character by character right, looking for the best fit.
bestEquality1 = equality1.toString();
bestEdit = edit;
bestEquality2 = equality2.toString();
bestScore = this.diffCleanupSemanticScore(equality1.toString(), edit)
+ this.diffCleanupSemanticScore(edit, equality2.toString());
while (!edit.isEmpty() && equality2.length() != 0
&& edit.charAt(0) == equality2.charAt(0)) {
equality1.append(Character.toString(edit.charAt(0)));
edit = edit.substring(1) + equality2.charAt(0);
String substring = equality2.substring(1);
equality2.setLength(0);
equality2.append(substring);
score = this.diffCleanupSemanticScore(equality1.toString(), edit)
+ this.diffCleanupSemanticScore(edit, equality2.toString());
// The >= encourages trailing rather than leading whitespace on edits.
if (score >= bestScore) {
bestScore = score;
bestEquality1 = equality1.toString();
bestEdit = edit;
bestEquality2 = equality2.toString();
}
}
if (!prevDiff.getText().equals(bestEquality1)) {
// We have an improvement, save it back to the diff.
if (!bestEquality1.isEmpty()) {
prevDiff.setText(bestEquality1);
} else {
pointer.previous(); // Walk past nextDiff.
pointer.previous(); // Walk past thisDiff.
pointer.previous(); // Walk past prevDiff.
pointer.remove(); // Delete prevDiff.
pointer.next(); // Walk past thisDiff.
pointer.next(); // Walk past nextDiff.
}
thisDiff.setText(bestEdit);
if (!bestEquality2.isEmpty()) {
nextDiff.setText(bestEquality2);
} else {
pointer.remove(); // Delete nextDiff.
nextDiff = thisDiff;
thisDiff = prevDiff;
}
}
}
prevDiff = thisDiff;
thisDiff = nextDiff;
nextDiff = pointer.hasNext() ? pointer.next() : null;
}
}
/**
* 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 diffCleanupSemanticScore(String one, String two) {
if (one.isEmpty() || two.isEmpty()) {
// 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.charAt(one.length() - 1);
char char2 = two.charAt(0);
boolean nonAlphaNumeric1 = !Character.isLetterOrDigit(char1);
boolean nonAlphaNumeric2 = !Character.isLetterOrDigit(char2);
boolean whitespace1 = nonAlphaNumeric1 && Character.isWhitespace(char1);
boolean whitespace2 = nonAlphaNumeric2 && Character.isWhitespace(char2);
boolean lineBreak1 = whitespace1
&& Character.getType(char1) == Character.CONTROL;
boolean lineBreak2 = whitespace2
&& Character.getType(char2) == Character.CONTROL;
boolean blankLine1 = lineBreak1 && BLANK_LINE_END.matcher(one).find();
boolean blankLine2 = lineBreak2 && BLANK_LINE_START.matcher(two).find();
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;
}
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public void diffCleanupEfficiency(LinkedList<Diff> diffs) {
if (diffs.isEmpty()) {
return;
}
boolean changes = false;
// Synchronized Stack to avoid Exception
Stack<Diff> equalities = new Stack<>(); // Stack of equalities.
String lastequality = null; // Always equal to equalities.lastElement().text
ListIterator<Diff> pointer = diffs.listIterator();
// Is there an insertion operation before the last equality.
boolean preIns = false;
// Is there a deletion operation before the last equality.
boolean preDel = false;
// Is there an insertion operation after the last equality.
boolean postIns = false;
// Is there a deletion operation after the last equality.
boolean postDel = false;
Diff thisDiff = pointer.next();
Diff safeDiff = thisDiff; // The last Diff that is known to be unsplitable.
while (thisDiff != null) {
if (thisDiff.getOperation() == Operation.EQUAL) {
// Equality found.
if (thisDiff.getText().length() < DIFF_EDIT_COST && (postIns || postDel)) {
// Candidate found.
equalities.push(thisDiff);
preIns = postIns;
preDel = postDel;
lastequality = thisDiff.getText();
} else {
// Not a candidate, and can never become one.
equalities.clear();
lastequality = null;
safeDiff = thisDiff;
}
postIns = postDel = false;
} else {
// An insertion or deletion.
if (thisDiff.getOperation() == Operation.DELETE) {
postDel = true;
} else {
postIns = 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 != null
&& (
(preIns && preDel && postIns && postDel)
|| (
(lastequality.length() < DIFF_EDIT_COST / 2)
&& ((preIns ? 1 : 0) + (preDel ? 1 : 0) + (postIns ? 1 : 0) + (postDel ? 1 : 0)) == 3
)
)
) {
// Walk back to offending equality.
while (thisDiff != equalities.lastElement()) {
thisDiff = pointer.previous();
}
pointer.next();
// Replace equality with a delete.
pointer.set(new Diff(Operation.DELETE, lastequality));
// Insert a corresponding an insert.
thisDiff = new Diff(Operation.INSERT, lastequality);
pointer.add(thisDiff);
equalities.pop(); // Throw away the equality we just deleted.
lastequality = null;
if (preIns && preDel) {
// No changes made which could affect previous entry, keep going.
postIns = postDel = true;
equalities.clear();
safeDiff = thisDiff;
} else {
if (!equalities.empty()) {
// Throw away the previous equality (it needs to be reevaluated).
equalities.pop();
}
if (equalities.empty()) {
// There are no previous questionable equalities,
// walk back to the last known safe diff.
thisDiff = safeDiff;
} else {
// There is an equality we can fall back to.
thisDiff = equalities.lastElement();
}
while (thisDiff != pointer.previous()) {
// Intentionally empty loop.
}
postIns = postDel = false;
}
changes = true;
}
}
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
if (changes) {
this.diffCleanupMerge(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 LinkedList of Diff objects.
*/
public void diffCleanupMerge(LinkedList<Diff> diffs) {
diffs.add(new Diff(Operation.EQUAL, "")); // Add a dummy entry at the end.
ListIterator<Diff> pointer = diffs.listIterator();
int countDelete = 0;
int countInsert = 0;
StringBuilder textDelete = new StringBuilder();
StringBuilder textInsert = new StringBuilder();
Diff thisDiff = pointer.next();
Diff prevEqual = null;
int commonlength;
while (thisDiff != null) {
switch (thisDiff.getOperation()) {
case INSERT:
countInsert++;
textInsert.append(thisDiff.getText());
prevEqual = null;
break;
case DELETE:
countDelete++;
textDelete.append(thisDiff.getText());
prevEqual = null;
break;
case EQUAL:
if (countDelete + countInsert > 1) {
boolean bothTypes = countDelete != 0 && countInsert != 0;
// Delete the offending records.
pointer.previous(); // Reverse direction.
while (countDelete-- > 0) {
pointer.previous();
pointer.remove();
}
while (countInsert-- > 0) {
pointer.previous();
pointer.remove();
}
if (bothTypes) {
// Factor out any common prefixies.
commonlength = this.diffCommonPrefix(textInsert.toString(), textDelete.toString());
if (commonlength != 0) {
if (pointer.hasPrevious()) {
thisDiff = pointer.previous();
// Previous diff should have been an equality: thisDiff.getOperation() == Operation.EQUAL")
thisDiff.setText(thisDiff.getText() + textInsert.substring(0, commonlength));
pointer.next();
} else {
pointer.add(new Diff(Operation.EQUAL,
textInsert.substring(0, commonlength)));
}
String substringIns = textInsert.substring(commonlength);
textInsert.setLength(0);
textInsert.append(substringIns);
String substringDel = textDelete.substring(commonlength);
textDelete.setLength(0);
textDelete.append(substringDel);
}
// Factor out any common suffixies.
commonlength = this.diffCommonSuffix(textInsert.toString(), textDelete.toString());
if (commonlength != 0) {
thisDiff = pointer.next();
thisDiff.setText(textInsert.substring(textInsert.length() - commonlength) + thisDiff.getText());
String substringIns = textInsert.substring(0, textInsert.length() - commonlength);
textInsert.setLength(0);
textInsert.append(substringIns);
String substringDel = textDelete.substring(0, textDelete.length() - commonlength);
textDelete.setLength(0);
textDelete.append(substringDel);
pointer.previous();
}
}
// Insert the merged records.
if (textDelete.length() != 0) {
pointer.add(new Diff(Operation.DELETE, textDelete.toString()));
}
if (textInsert.length() != 0) {
pointer.add(new Diff(Operation.INSERT, textInsert.toString()));
}
// Step forward to the equality.
thisDiff = pointer.hasNext() ? pointer.next() : null;
} else if (prevEqual != null) {
// Merge this equality with the previous one.
prevEqual.setText(prevEqual.getText() + thisDiff.getText());
pointer.remove();
thisDiff = pointer.previous();
pointer.next(); // Forward direction
}
countInsert = 0;
countDelete = 0;
textDelete.setLength(0);
textInsert.setLength(0);
prevEqual = thisDiff;
break;
}
thisDiff = pointer.hasNext() ? pointer.next() : null;
}
if (diffs.getLast().getText().isEmpty()) {
diffs.removeLast(); // 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
*/
boolean changes = false;
// Create a new iterator at the start.
// (As opposed to walking the current one back.)
pointer = diffs.listIterator();
Diff prevDiff = pointer.hasNext() ? pointer.next() : null;
thisDiff = pointer.hasNext() ? pointer.next() : null;
Diff nextDiff = pointer.hasNext() ? pointer.next() : null;
// Intentionally ignore the first and last element (don't need checking).
while (nextDiff != null) {
if (prevDiff.getOperation() == Operation.EQUAL &&
nextDiff.getOperation() == Operation.EQUAL) {
// This is a single edit surrounded by equalities.
if (thisDiff.getText().endsWith(prevDiff.getText())) {
// Shift the edit over the previous equality.
thisDiff.setText(prevDiff.getText()
+ thisDiff.getText().substring(0, thisDiff.getText().length()
- prevDiff.getText().length()));
nextDiff.setText(prevDiff.getText() + nextDiff.getText());
pointer.previous(); // Walk past nextDiff.
pointer.previous(); // Walk past thisDiff.
pointer.previous(); // Walk past prevDiff.
pointer.remove(); // Delete prevDiff.
pointer.next(); // Walk past thisDiff.
thisDiff = pointer.next(); // Walk past nextDiff.
nextDiff = pointer.hasNext() ? pointer.next() : null;
changes = true;
} else if (thisDiff.getText().startsWith(nextDiff.getText())) {
// Shift the edit over the next equality.
prevDiff.setText(prevDiff.getText() + nextDiff.getText());
thisDiff.setText(thisDiff.getText().substring(nextDiff.getText().length())
+ nextDiff.getText());
pointer.remove(); // Delete nextDiff.
nextDiff = pointer.hasNext() ? pointer.next() : null;
changes = true;
}
}
prevDiff = thisDiff;
thisDiff = nextDiff;
nextDiff = pointer.hasNext() ? pointer.next() : null;
}
// If shifts were made, the diff needs reordering and another shift sweep.
if (changes) {
this.diffCleanupMerge(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 diffXIndex(List<Diff> diffs, int loc) {
int chars1 = 0;
int chars2 = 0;
int lastChars1 = 0;
int lastChars2 = 0;
Diff lastDiff = null;
for (Diff aDiff : diffs) {
if (aDiff.getOperation() != Operation.INSERT) {
// Equality or deletion.
chars1 += aDiff.getText().length();
}
if (aDiff.getOperation() != Operation.DELETE) {
// Equality or insertion.
chars2 += aDiff.getText().length();
}
if (chars1 > loc) {
// Overshot the location.
lastDiff = aDiff;
break;
}
lastChars1 = chars1;
lastChars2 = chars2;
}
if (lastDiff != null && lastDiff.getOperation() == Operation.DELETE) {
// The location was deleted.
return lastChars2;
}
// Add the remaining character length.
return lastChars2 + (loc - lastChars1);
}
/**
* Convert a Diff list into a pretty HTML report.
* @param diffs List of Diff objects.
* @return HTML representation.
*/
public String diffPrettyHtml(List<Diff> diffs) {
StringBuilder html = new StringBuilder();
for (Diff aDiff : diffs) {
String text = aDiff.getText().replace("&", "&").replace("<", "<")
.replace(">", ">").replace("\n", "¶<br>");
switch (aDiff.getOperation()) {
case INSERT:
html.append("<ins style=\"background:#e6ffe6;\">").append(text)
.append("</ins>");
break;
case DELETE:
html.append("<del style=\"background:#ffe6e6;\">").append(text)
.append("</del>");
break;
case 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 diffText1(List<Diff> diffs) {
StringBuilder text = new StringBuilder();
for (Diff aDiff : diffs) {
if (aDiff.getOperation() != Operation.INSERT) {
text.append(aDiff.getText());
}
}
return text.toString();
}
/**
* Compute and return the destination text (all equalities and insertions).
* @param diffs List of Diff objects.
* @return Destination text.
*/
public String diffText2(List<Diff> diffs) {
StringBuilder text = new StringBuilder();
for (Diff aDiff : diffs) {
if (aDiff.getOperation() != Operation.DELETE) {
text.append(aDiff.getText());
}
}
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 diffLevenshtein(List<Diff> diffs) {
int levenshtein = 0;
int insertions = 0;
int deletions = 0;
for (Diff aDiff : diffs) {
switch (aDiff.getOperation()) {
case INSERT:
insertions += aDiff.getText().length();
break;
case DELETE:
deletions += aDiff.getText().length();
break;
case 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 diffToDelta(List<Diff> diffs) {
StringBuilder text = new StringBuilder();
for (Diff aDiff : diffs) {
switch (aDiff.getOperation()) {
case INSERT:
text.append("+").append(URLEncoder.encode(aDiff.getText(), StandardCharsets.UTF_8)
.replace('+', ' ')).append("\t");
break;
case DELETE:
text.append("-").append(aDiff.getText().length()).append("\t");
break;
case EQUAL:
text.append("=").append(aDiff.getText().length()).append("\t");
break;
}
}
String delta = text.toString();
if (!delta.isEmpty()) {
// Strip off trailing tab character.
delta = delta.substring(0, delta.length() - 1);
delta = Patch.unescapeForEncodeUriCompatability(delta);
}
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.
*/
public List<Diff> diffFromDelta(String text1, String delta) {
List<Diff> diffs = new LinkedList<>();
int pointer = 0; // Cursor in text1
String[] tokens = delta.split("\t");
for (String token : tokens) {
if (token.isEmpty()) {
// 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.charAt(0)) {
case '+':
// decode would change all "+" to " "
param = param.replace("+", "%2B");
try {
param = URLDecoder.decode(param, StandardCharsets.UTF_8);
} 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 = Integer.parseInt(param);
} catch (NumberFormatException e) {
throw new IllegalArgumentException(
"Invalid number in diff_fromDelta: " + param, e);
}
if (n < 0) {
throw new IllegalArgumentException(
"Negative number in diff_fromDelta: " + param);
}
String text;
try {
int p1 = pointer;
pointer += n;
int p2 = pointer;
text = text1.substring(p1, p2);
} catch (StringIndexOutOfBoundsException e) {
throw new IllegalArgumentException("Delta length (" + pointer
+ ") larger than source text length (" + text1.length()
+ ").", e);
}
if (token.charAt(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 IllegalArgumentException(
"Invalid diff operation in diff_fromDelta: " + token.charAt(0));
}
}
if (pointer != text1.length()) {
throw new IllegalArgumentException("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 valueLoc The location to search around.
* @return Best match index or -1.
*/
public int matchMain(String text, String pattern, int valueLoc) {
// Check for null inputs.
if (text == null || pattern == null) {
throw new IllegalArgumentException("Null inputs. (match_main)");
}
int loc = Math.max(0, Math.min(valueLoc, text.length()));
if (text.equals(pattern)) {
// Shortcut (potentially not guaranteed by the algorithm)
return 0;
} else if (text.isEmpty()) {
// Nothing to match.
return -1;
} else if (loc + pattern.length() <= text.length()
&& text.substring(loc, loc + pattern.length()).equals(pattern)) {
// Perfect match at the perfect spot! (Includes case of null pattern)
return loc;
} else {
// Do a fuzzy compare.
return this.matchBitap(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 matchBitap(String text, String pattern, int loc) {
// Initialise the alphabet.
Map<Character, Integer> s = this.matchAlphabet(pattern);
// Highest score beyond which we give up.
double scoreThreshold = MATCH_THRESHOLD;
// Is there a nearby exact match? (speedup)
int bestLoc = text.indexOf(pattern, loc);
if (bestLoc != -1) {
scoreThreshold = Math.min(this.matchBitapScore(0, bestLoc, loc, pattern),
scoreThreshold);
// What about in the other direction? (speedup)
bestLoc = text.lastIndexOf(pattern, loc + pattern.length());
if (bestLoc != -1) {
scoreThreshold = Math.min(this.matchBitapScore(0, bestLoc, loc, pattern),
scoreThreshold);
}
}
// Initialise the bit arrays.
int matchmask = 1 << (pattern.length() - 1);
bestLoc = -1;
int binMin;
int binMid;
int binMax = pattern.length() + text.length();
// Empty initialization added to appease Java compiler.
int[] lastRd = 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.
binMin = 0;
binMid = binMax;
while (binMin < binMid) {
if (this.matchBitapScore(d, loc + binMid, loc, pattern)
<= scoreThreshold) {
binMin = binMid;
} else {
binMax = binMid;
}
binMid = (binMax - binMin) / 2 + binMin;
}
// Use the result from this iteration as the maximum for the next.
binMax = binMid;
int start = Math.max(1, loc - binMid + 1);
int finish = Math.min(loc + binMid, 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.charAt(j - 1))) {
// Out of range.
charMatch = 0;
} else {
charMatch = s.get(text.charAt(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)
| (((lastRd[j + 1] | lastRd[j]) << 1) | 1) | lastRd[j + 1];
}
if ((rd[j] & matchmask) != 0) {
double score = this.matchBitapScore(d, j - 1, loc, pattern);
// This match will almost certainly be better than any existing
// match. But check anyway.
if (score <= scoreThreshold) {
// Told you so.
scoreThreshold = score;
bestLoc = j - 1;
if (bestLoc > loc) {
// When passing loc, don't exceed our current distance from loc.
start = Math.max(1, 2 * loc - bestLoc);
} else {
// Already passed loc, downhill from here on in.
break;
}
}
}
}
if (this.matchBitapScore(d + 1, loc, loc, pattern) > scoreThreshold) {
// No hope for a (better) match at greater error levels.
break;
}
lastRd = rd;
}
return bestLoc;
}
/**
* 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 matchBitapScore(int e, int x, int loc, String pattern) {
float accuracy = (float) e / pattern.length();
int proximity = Math.abs(loc - x);
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 Map<Character, Integer> matchAlphabet(String pattern) {
Map<Character, Integer> s = new HashMap<>();
char[] charPattern = pattern.toCharArray();
for (char c : charPattern) {
s.put(c, 0);
}
int i = 0;
for (char c : charPattern) {
s.put(c, s.get(c) | (1 << (pattern.length() - i - 1)));
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 patchAddContext(Patch patch, String text) {
if (text.isEmpty()) {
return;
}
String pattern = text.substring(patch.getStart2(), patch.getStart2() + patch.getLength1());
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) != text.lastIndexOf(pattern)
&& pattern.length() < DiffMatchPatch.MATCH_MAX_BITS - PATCH_MARGIN - PATCH_MARGIN) {
padding += PATCH_MARGIN;
pattern = text.substring(Math.max(0, patch.getStart2() - padding),
Math.min(text.length(), patch.getStart2() + patch.getLength1() + padding));
}
// Add one chunk for good luck.
padding += PATCH_MARGIN;
// Add the prefix.
String prefix = text.substring(Math.max(0, patch.getStart2() - padding),
patch.getStart2());
if (!prefix.isEmpty()) {
patch.getDiffs().addFirst(new Diff(Operation.EQUAL, prefix));
}
// Add the suffix.
String suffix = text.substring(patch.getStart2() + patch.getLength1(),
Math.min(text.length(), patch.getStart2() + patch.getLength1() + padding));
if (!suffix.isEmpty()) {
patch.getDiffs().addLast(new Diff(Operation.EQUAL, suffix));
}
// Roll back the start points.
patch.setStart1(patch.getStart1() - prefix.length());
patch.setStart2(patch.getStart2() - prefix.length());
// Extend the lengths.
patch.setLength1(patch.getLength1() + prefix.length() + suffix.length());
patch.setLength2(patch.getLength2() + 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 LinkedList of Patch objects.
*/
public List<Patch> patchMake(String text1, String text2) {
if (text1 == null || text2 == null) {
throw new IllegalArgumentException("Null inputs. (patch_make)");
}
// No diffs provided, compute our own.
LinkedList<Diff> diffs = this.diffMain(text1, text2, true);
if (diffs.size() > 2) {
this.diffCleanupSemantic(diffs);
this.diffCleanupEfficiency(diffs);
}
return this.patchMake(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 LinkedList of Patch objects.
*/
public List<Patch> patchMake(LinkedList<Diff> diffs) {
if (diffs == null) {
throw new IllegalArgumentException("Null inputs. (patch_make)");
}
// No origin string provided, compute our own.
String text1 = this.diffText1(diffs);
return this.patchMake(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 Deque of Patch objects.
*/
public List<Patch> patchMake(String text1, Deque<Diff> diffs) {
if (text1 == null || diffs == null) {
throw new IllegalArgumentException("Null inputs. (patch_make)");
}
List<Patch> patches = new LinkedList<>();
if (diffs.isEmpty()) {
return patches; // Get rid of the null case.
}
Patch patch = new Patch();
int charCount1 = 0; // Number of characters into the text1 string.
int charCount2 = 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 prepatchText = text1;
String postpatchText = text1;
for (Diff aDiff : diffs) {
if (patch.getDiffs().isEmpty() && aDiff.getOperation() != Operation.EQUAL) {
// A new patch starts here.
patch.setStart1(charCount1);
patch.setStart2(charCount2);
}
switch (aDiff.getOperation()) {
case INSERT:
patch.getDiffs().add(aDiff);
patch.setLength2(patch.getLength2() + aDiff.getText().length());
postpatchText = postpatchText.substring(0, charCount2)
+ aDiff.getText() + postpatchText.substring(charCount2);
break;
case DELETE:
patch.setLength1(patch.getLength1() + aDiff.getText().length());
patch.getDiffs().add(aDiff);
postpatchText = postpatchText.substring(0, charCount2)
+ postpatchText.substring(charCount2 + aDiff.getText().length());
break;
case EQUAL:
if (
aDiff.getText().length() <= 2 * PATCH_MARGIN
&& !patch.getDiffs().isEmpty() && aDiff != diffs.getLast()
) {
// Small equality inside a patch.
patch.getDiffs().add(aDiff);
patch.setLength1(patch.getLength1() + aDiff.getText().length());
patch.setLength2(patch.getLength2() + aDiff.getText().length());
}
if (
aDiff.getText().length() >= 2 * PATCH_MARGIN
&& !patch.getDiffs().isEmpty()
) {
// Time for a new patch.
this.patchAddContext(patch, prepatchText);
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.
prepatchText = postpatchText;
charCount1 = charCount2;
}
break;
}
// Update the current character count.
if (aDiff.getOperation() != Operation.INSERT) {
charCount1 += aDiff.getText().length();
}
if (aDiff.getOperation() != Operation.DELETE) {
charCount2 += aDiff.getText().length();
}
}
// Pick up the leftover patch if not empty.
if (!patch.getDiffs().isEmpty()) {
this.patchAddContext(patch, prepatchText);
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 LinkedList<Patch> patchDeepCopy(List<Patch> patches) {
LinkedList<Patch> patchesCopy = new LinkedList<>();
for (Patch aPatch : patches) {
Patch patchCopy = new Patch();
for (Diff aDiff : aPatch.getDiffs()) {
Diff diffCopy = new Diff(aDiff.getOperation(), aDiff.getText());
patchCopy.getDiffs().add(diffCopy);
}
patchCopy.setStart1(aPatch.getStart1());
patchCopy.setStart2(aPatch.getStart2());
patchCopy.setLength1(aPatch.getLength1());
patchCopy.setLength2(aPatch.getLength2());
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 valuePatches Array of Patch objects
* @param valueText Old text.
* @return Two element Object array, containing the new text and an array of
* boolean values.
*/
public Object[] patchApply(LinkedList<Patch> valuePatches, String valueText) {
if (valuePatches.isEmpty()) {
return new Object[]{valueText, new boolean[0]};
}
// Deep copy the patches so that no changes are made to originals.
LinkedList<Patch> patches = this.patchDeepCopy(valuePatches);
String nullPadding = this.patchAddPadding(patches);
String text = nullPadding + valueText + nullPadding;
this.patchSplitMax(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;
boolean[] results = new boolean[patches.size()];
for (Patch aPatch : patches) {
int expectedLoc = aPatch.getStart2() + delta;
String text1 = this.diffText1(aPatch.getDiffs());
int startLoc;
int endLoc = -1;
if (text1.length() > DiffMatchPatch.MATCH_MAX_BITS) {
// patch_splitMax will only provide an oversized pattern in the case of
// a monster delete.
startLoc = this.matchMain(text,
text1.substring(0, DiffMatchPatch.MATCH_MAX_BITS), expectedLoc);
if (startLoc != -1) {
endLoc = this.matchMain(text,
text1.substring(text1.length() - DiffMatchPatch.MATCH_MAX_BITS),
expectedLoc + text1.length() - DiffMatchPatch.MATCH_MAX_BITS);
if (endLoc == -1 || startLoc >= endLoc) {
// Can't find valid trailing context. Drop this patch.
startLoc = -1;
}
}
} else {
startLoc = this.matchMain(text, text1, expectedLoc);
}
if (startLoc == -1) {
// No match found. :(
results[x] = false;
// Subtract the delta for this failed patch from subsequent patches.
delta -= aPatch.getLength2() - aPatch.getLength1();
} else {
// Found a match. :)
results[x] = true;
delta = startLoc - expectedLoc;
String text2;
if (endLoc == -1) {
text2 = text.substring(startLoc,
Math.min(startLoc + text1.length(), text.length()));
} else {
text2 = text.substring(startLoc,
Math.min(endLoc + DiffMatchPatch.MATCH_MAX_BITS, text.length()));
}
if (text1.equals(text2)) {
// Perfect match, just shove the replacement text in.
text = text.substring(0, startLoc) + this.diffText2(aPatch.getDiffs())
+ text.substring(startLoc + text1.length());
} else {
// Imperfect match. Run a diff to get a framework of equivalent
// indices.
List<Diff> diffs = this.diffMain(text1, text2, false);
if (text1.length() > DiffMatchPatch.MATCH_MAX_BITS
&& this.diffLevenshtein(diffs) / (float) text1.length()
> DiffMatchPatch.PATCH_DELETE_THRESHOLD) {
// The end points match, but the content is unacceptably bad.
results[x] = false;
} else {
this.diffCleanupSemanticLossless(diffs);
int index1 = 0;
for (Diff aDiff : aPatch.getDiffs()) {
if (aDiff.getOperation() != Operation.EQUAL) {
int index2 = this.diffXIndex(diffs, index1);
if (aDiff.getOperation() == Operation.INSERT) {
// Insertion
text = text.substring(0, startLoc + index2) + aDiff.getText()
+ text.substring(startLoc + index2);
} else if (aDiff.getOperation() == Operation.DELETE) {
// Deletion
text = text.substring(0, startLoc + index2)
+ text.substring(startLoc + this.diffXIndex(diffs,
index1 + aDiff.getText().length()));
}
}
if (aDiff.getOperation() != Operation.DELETE) {
index1 += aDiff.getText().length();
}
}
}
}
}
x++;
}
// Strip the padding off.
text = text.substring(nullPadding.length(), text.length()
- 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 patchAddPadding(Deque<Patch> patches) {
short paddingLength = DiffMatchPatch.PATCH_MARGIN;
StringBuilder nullPadding = new StringBuilder();
for (short x = 1; x <= paddingLength; x++) {
nullPadding.append(String.valueOf((char) x));
}
// Bump all the patches forward.
for (Patch aPatch : patches) {
aPatch.setStart1(aPatch.getStart1() + paddingLength);
aPatch.setStart2(aPatch.getStart2() + paddingLength);
}
// Add some padding on start of first diff.
Patch patch = patches.getFirst();
Deque<Diff> diffs = patch.getDiffs();
if (diffs.isEmpty() || diffs.getFirst().getOperation() != Operation.EQUAL) {
// Add nullPadding equality.
diffs.addFirst(new Diff(Operation.EQUAL, nullPadding.toString()));
patch.setStart1(patch.getStart1() - paddingLength); // Should be 0.
patch.setStart2(patch.getStart2() - paddingLength); // Should be 0.
patch.setLength1(patch.getLength1() + paddingLength);
patch.setLength2(patch.getLength2() + paddingLength);
} else if (paddingLength > diffs.getFirst().getText().length()) {
// Grow first equality.
Diff firstDiff = diffs.getFirst();
int extraLength = paddingLength - firstDiff.getText().length();
firstDiff.setText(nullPadding.substring(firstDiff.getText().length())
+ firstDiff.getText());
patch.setStart1(patch.getStart1() - extraLength);
patch.setStart2(patch.getStart2() - extraLength);
patch.setLength1(patch.getLength1() + extraLength);
patch.setLength2(patch.getLength2() + extraLength);
}
// Add some padding on end of last diff.
patch = patches.getLast();
diffs = patch.getDiffs();
if (diffs.isEmpty() || diffs.getLast().getOperation() != Operation.EQUAL) {
// Add nullPadding equality.
diffs.addLast(new Diff(Operation.EQUAL, nullPadding.toString()));
patch.setLength1(patch.getLength1() + paddingLength);
patch.setLength2(patch.getLength2() + paddingLength);
} else if (paddingLength > diffs.getLast().getText().length()) {
// Grow last equality.
Diff lastDiff = diffs.getLast();
int extraLength = paddingLength - lastDiff.getText().length();
lastDiff.setText(lastDiff.getText() + nullPadding.substring(0, extraLength));
patch.setLength1(patch.getLength1() + extraLength);
patch.setLength2(patch.getLength2() + extraLength);
}
return nullPadding.toString();
}
/**
* 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 patchSplitMax(List<Patch> patches) {
short patchSize = DiffMatchPatch.MATCH_MAX_BITS;
String precontext;
String postcontext;
Patch patch;
int start1;
int start2;
boolean empty;
Operation diffType;
String diffText;
ListIterator<Patch> pointer = patches.listIterator();
Patch bigpatch = pointer.hasNext() ? pointer.next() : null;
while (bigpatch != null) {
if (bigpatch.getLength1() <= DiffMatchPatch.MATCH_MAX_BITS) {
bigpatch = pointer.hasNext() ? pointer.next() : null;
continue;
}
// Remove the big old patch.
pointer.remove();
start1 = bigpatch.getStart1();
start2 = bigpatch.getStart2();
precontext = "";
while (!bigpatch.getDiffs().isEmpty()) {
// Create one of several smaller patches.
patch = new Patch();
empty = true;
patch.setStart1(start1 - precontext.length());
patch.setStart2(start2 - precontext.length());
if (!precontext.isEmpty()) {
patch.setLength1(patch.setLength2(precontext.length()));
patch.getDiffs().add(new Diff(Operation.EQUAL, precontext));
}
while (!bigpatch.getDiffs().isEmpty()
&& patch.getLength1() < patchSize - PATCH_MARGIN) {
diffType = bigpatch.getDiffs().getFirst().getOperation();
diffText = bigpatch.getDiffs().getFirst().getText();
if (diffType == Operation.INSERT) {
// Insertions are harmless.
patch.setLength2(patch.getLength2() + diffText.length());
start2 += diffText.length();
patch.getDiffs().addLast(bigpatch.getDiffs().removeFirst());
empty = false;
} else if (diffType == Operation.DELETE && patch.getDiffs().size() == 1
&& patch.getDiffs().getFirst().getOperation() == Operation.EQUAL
&& diffText.length() > 2 * patchSize) {
// This is a large deletion. Let it pass in one chunk.
patch.setLength1(patch.getLength1() + diffText.length());
start1 += diffText.length();
empty = false;
patch.getDiffs().add(new Diff(diffType, diffText));
bigpatch.getDiffs().removeFirst();
} else {
// Deletion or equality. Only take as much as we can stomach.
diffText = diffText.substring(0, Math.min(diffText.length(),
patchSize - patch.getLength1() - PATCH_MARGIN));
patch.setLength1(patch.getLength1() + diffText.length());
start1 += diffText.length();
if (diffType == Operation.EQUAL) {
patch.setLength2(patch.getLength2() + diffText.length());
start2 += diffText.length();
} else {
empty = false;
}
patch.getDiffs().add(new Diff(diffType, diffText));
if (diffText.equals(bigpatch.getDiffs().getFirst().getText())) {
bigpatch.getDiffs().removeFirst();
} else {
bigpatch.getDiffs().getFirst().setText(bigpatch.getDiffs().getFirst().getText()
.substring(diffText.length()));
}
}
}
// Compute the head context for the next patch.
precontext = this.diffText2(patch.getDiffs());
precontext = precontext.substring(Math.max(0, precontext.length()
- PATCH_MARGIN));
// Append the end context for this patch.
if (this.diffText1(bigpatch.getDiffs()).length() > PATCH_MARGIN) {
postcontext = this.diffText1(bigpatch.getDiffs()).substring(0, PATCH_MARGIN);
} else {
postcontext = this.diffText1(bigpatch.getDiffs());
}
if (!postcontext.isEmpty()) {
patch.setLength1(patch.getLength1() + postcontext.length());
patch.setLength2(patch.getLength2() + postcontext.length());
if (!patch.getDiffs().isEmpty()
&& patch.getDiffs().getLast().getOperation() == Operation.EQUAL) {
patch.getDiffs().getLast().setText(patch.getDiffs().getLast().getText() + postcontext);
} else {
patch.getDiffs().add(new Diff(Operation.EQUAL, postcontext));
}
}
if (!empty) {
pointer.add(patch);
}
}
bigpatch = pointer.hasNext() ? pointer.next() : null;
}
}
/**
* Take a list of patches and return a textual representation.
* @param patches List of Patch objects.
* @return Text representation of patches.
*/
public String patchToText(List<Patch> patches) {
StringBuilder text = new StringBuilder();
for (Patch aPatch : 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.
*/
public List<Patch> patchFromText(String textline) {
List<Patch> patches = new LinkedList<>();
if (textline.isEmpty()) {
return patches;
}
List<String> textList = Arrays.asList(textline.split("\n"));
Deque<String> text = new LinkedList<>(textList);
Patch patch;
Pattern patchHeader = Pattern.compile("^@@ -(\\d+),?(\\d*) \\+(\\d+),?(\\d*) @@$");
Matcher m;
char sign;
String line;
while (!text.isEmpty()) {
m = patchHeader.matcher(text.getFirst());
if (!m.matches()) {
throw new IllegalArgumentException(
"Invalid patch string: " + text.getFirst());
}
patch = new Patch();
patches.add(patch);
patch.setStart1(Integer.parseInt(m.group(1)));
if (m.group(2).isEmpty()) {
patch.setStart1(patch.getStart1() - 1);
patch.setLength1(1);
} else if ("0".equals(m.group(2))) {
patch.setLength1(0);
} else {
patch.setStart1(patch.getStart1() - 1);
patch.setLength1(Integer.parseInt(m.group(2)));
}
patch.setStart2(Integer.parseInt(m.group(3)));
if (m.group(4).isEmpty()) {
patch.setStart2(patch.getStart2() - 1);
patch.setLength2(1);
} else if ("0".equals(m.group(4))) {
patch.setLength2(0);
} else {
patch.setStart2(patch.getStart2() - 1);
patch.setLength2(Integer.parseInt(m.group(4)));
}
text.removeFirst();
while (!text.isEmpty()) {
try {
sign = text.getFirst().charAt(0);
} catch (IndexOutOfBoundsException e) {
LOGGER.log(LogLevelUtil.IGNORE, e);
// Blank line? Whatever.
text.removeFirst();
continue;
}
line = text.getFirst().substring(1);
line = line.replace("+", "%2B"); // decode would change all "+" to " "
try {
line = URLDecoder.decode(line, StandardCharsets.UTF_8);
} catch (IllegalArgumentException e) {
// Malformed URI sequence.
throw new IllegalArgumentException(
"Illegal escape in patch_fromText: " + line, e);
}
if (sign == '-') {
// Deletion.
patch.getDiffs().add(new Diff(Operation.DELETE, line));
} else if (sign == '+') {
// Insertion.
patch.getDiffs().add(new Diff(Operation.INSERT, line));
} else if (sign == ' ') {
// Minor equality.
patch.getDiffs().add(new Diff(Operation.EQUAL, line));
} else if (sign == '@') {
// Start of next patch.
break;
} else {
// WTF?
throw new IllegalArgumentException(
"Invalid patch mode '" + sign + "' in: " + line);
}
text.removeFirst();
}
}
return patches;
}
}