| /* |
| * 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. |
| */ |
| |
| package name.fraser.neil.plaintext; |
| |
| import java.io.UnsupportedEncodingException; |
| import java.net.URLEncoder; |
| import java.net.URLDecoder; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.LinkedList; |
| import java.util.List; |
| import java.util.ListIterator; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.Stack; |
| 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 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; |
| /** |
| * The size beyond which the double-ended diff activates. |
| * Double-ending is twice as fast, but less accurate. |
| */ |
| public short Diff_DualThreshold = 32; |
| /** |
| * 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 does |
| * the contents have 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 int Match_MaxBits = 32; |
| |
| /** |
| * Internal class for returning results from diff_linesToChars(). |
| * Other less paranoid languages just use a three-element array. |
| */ |
| protected static class LinesToCharsResult { |
| protected String chars1; |
| protected String chars2; |
| protected 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 LinkedList<Diff> diff_main(String text1, String text2) { |
| return diff_main(text1, text2, true); |
| } |
| |
| /** |
| * 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 |
| * @return Linked List of Diff objects. |
| */ |
| public LinkedList<Diff> diff_main(String text1, String text2, |
| boolean checklines) { |
| // 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<Diff>(); |
| 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); |
| |
| // Restore the prefix and suffix. |
| if (commonprefix.length() != 0) { |
| diffs.addFirst(new Diff(Operation.EQUAL, commonprefix)); |
| } |
| if (commonsuffix.length() != 0) { |
| diffs.addLast(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 |
| * @return Linked List of Diff objects. |
| */ |
| protected LinkedList<Diff> diff_compute(String text1, String text2, |
| boolean checklines) { |
| LinkedList<Diff> diffs = new LinkedList<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); |
| 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; |
| } |
| longtext = shorttext = null; // Garbage collect. |
| |
| // 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. |
| LinkedList<Diff> diffs_a = diff_main(text1_a, text2_a, checklines); |
| LinkedList<Diff> diffs_b = diff_main(text1_b, text2_b, checklines); |
| // Merge the results. |
| diffs = diffs_a; |
| diffs.add(new Diff(Operation.EQUAL, mid_common)); |
| diffs.addAll(diffs_b); |
| return diffs; |
| } |
| |
| // Perform a real diff. |
| if (checklines && (text1.length() < 100 || text2.length() < 100)) { |
| checklines = false; // Too trivial for the overhead. |
| } |
| List<String> linearray = null; |
| if (checklines) { |
| // Scan the text on a line-by-line basis first. |
| LinesToCharsResult b = diff_linesToChars(text1, text2); |
| text1 = b.chars1; |
| text2 = b.chars2; |
| linearray = b.lineArray; |
| } |
| |
| diffs = diff_map(text1, text2); |
| if (diffs == null) { |
| // No acceptable result. |
| diffs = new LinkedList<Diff>(); |
| diffs.add(new Diff(Operation.DELETE, text1)); |
| diffs.add(new Diff(Operation.INSERT, text2)); |
| } |
| |
| if (checklines) { |
| // 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, "")); |
| int count_delete = 0; |
| int count_insert = 0; |
| String text_delete = ""; |
| String text_insert = ""; |
| ListIterator<Diff> pointer = diffs.listIterator(); |
| Diff thisDiff = pointer.next(); |
| while (thisDiff != null) { |
| switch (thisDiff.operation) { |
| case INSERT: |
| count_insert++; |
| text_insert += thisDiff.text; |
| break; |
| case DELETE: |
| count_delete++; |
| text_delete += thisDiff.text; |
| break; |
| case 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. |
| pointer.previous(); |
| for (int j = 0; j < count_delete + count_insert; j++) { |
| pointer.previous(); |
| pointer.remove(); |
| } |
| for (Diff newDiff : diff_main(text_delete, text_insert, false)) { |
| pointer.add(newDiff); |
| } |
| } |
| count_insert = 0; |
| count_delete = 0; |
| text_delete = ""; |
| text_insert = ""; |
| break; |
| } |
| thisDiff = pointer.hasNext() ? pointer.next() : null; |
| } |
| diffs.removeLast(); // Remove the dummy entry at the end. |
| } |
| 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 diff_linesToChars(String text1, String text2) { |
| List<String> lineArray = new ArrayList<String>(); |
| Map<String, Integer> lineHash = new HashMap<String, Integer>(); |
| // 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 = diff_linesToCharsMunge(text1, lineArray, lineHash); |
| String chars2 = diff_linesToCharsMunge(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 diff_linesToCharsMunge(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 diff_charsToLines(LinkedList<Diff> diffs, |
| List<String> lineArray) { |
| StringBuilder text; |
| for (Diff diff : diffs) { |
| text = new StringBuilder(); |
| for (int y = 0; y < diff.text.length(); y++) { |
| text.append(lineArray.get(diff.text.charAt(y))); |
| } |
| diff.text = text.toString(); |
| } |
| } |
| |
| |
| /** |
| * Explore the intersection points between the two texts. |
| * @param text1 Old string to be diffed. |
| * @param text2 New string to be diffed. |
| * @return LinkedList of Diff objects or null if no diff available. |
| */ |
| protected LinkedList<Diff> diff_map(String text1, String text2) { |
| long ms_end = System.currentTimeMillis() + (long) (Diff_Timeout * 1000); |
| // 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; |
| boolean doubleEnd = Diff_DualThreshold * 2 < max_d; |
| List<Set<Long>> v_map1 = new ArrayList<Set<Long>>(); |
| List<Set<Long>> v_map2 = new ArrayList<Set<Long>>(); |
| Map<Integer, Integer> v1 = new HashMap<Integer, Integer>(); |
| Map<Integer, Integer> v2 = new HashMap<Integer, Integer>(); |
| v1.put(1, 0); |
| v2.put(1, 0); |
| int x, y; |
| Long footstep = 0L; // Used to track overlapping paths. |
| Map<Long, Integer> footsteps = new HashMap<Long, Integer>(); |
| boolean done = false; |
| // If the total number of characters is odd, then the front path will |
| // collide with the reverse path. |
| boolean front = ((text1_length + text2_length) % 2 == 1); |
| for (int d = 0; d < max_d; d++) { |
| // Bail out if timeout reached. |
| if (Diff_Timeout > 0 && System.currentTimeMillis() > ms_end) { |
| return null; |
| } |
| |
| // Walk the front path one step. |
| v_map1.add(new HashSet<Long>()); // Adds at index 'd'. |
| for (int k = -d; k <= d; k += 2) { |
| if (k == -d || k != d && v1.get(k - 1) < v1.get(k + 1)) { |
| x = v1.get(k + 1); |
| } else { |
| x = v1.get(k - 1) + 1; |
| } |
| y = x - k; |
| if (doubleEnd) { |
| footstep = diff_footprint(x, y); |
| if (front && (footsteps.containsKey(footstep))) { |
| done = true; |
| } |
| if (!front) { |
| footsteps.put(footstep, d); |
| } |
| } |
| while (!done && x < text1_length && y < text2_length |
| && text1.charAt(x) == text2.charAt(y)) { |
| x++; |
| y++; |
| if (doubleEnd) { |
| footstep = diff_footprint(x, y); |
| if (front && (footsteps.containsKey(footstep))) { |
| done = true; |
| } |
| if (!front) { |
| footsteps.put(footstep, d); |
| } |
| } |
| } |
| v1.put(k, x); |
| v_map1.get(d).add(diff_footprint(x, y)); |
| if (x == text1_length && y == text2_length) { |
| // Reached the end in single-path mode. |
| return diff_path1(v_map1, text1, text2); |
| } else if (done) { |
| // Front path ran over reverse path. |
| v_map2 = v_map2.subList(0, footsteps.get(footstep) + 1); |
| LinkedList<Diff> a = diff_path1(v_map1, text1.substring(0, x), |
| text2.substring(0, y)); |
| a.addAll(diff_path2(v_map2, text1.substring(x), text2.substring(y))); |
| return a; |
| } |
| } |
| |
| if (doubleEnd) { |
| // Walk the reverse path one step. |
| v_map2.add(new HashSet<Long>()); // Adds at index 'd'. |
| for (int k = -d; k <= d; k += 2) { |
| if (k == -d || k != d && v2.get(k - 1) < v2.get(k + 1)) { |
| x = v2.get(k + 1); |
| } else { |
| x = v2.get(k - 1) + 1; |
| } |
| y = x - k; |
| footstep = diff_footprint(text1_length - x, text2_length - y); |
| if (!front && (footsteps.containsKey(footstep))) { |
| done = true; |
| } |
| if (front) { |
| footsteps.put(footstep, d); |
| } |
| while (!done && x < text1_length && y < text2_length |
| && text1.charAt(text1_length - x - 1) |
| == text2.charAt(text2_length - y - 1)) { |
| x++; |
| y++; |
| footstep = diff_footprint(text1_length - x, text2_length - y); |
| if (!front && (footsteps.containsKey(footstep))) { |
| done = true; |
| } |
| if (front) { |
| footsteps.put(footstep, d); |
| } |
| } |
| v2.put(k, x); |
| v_map2.get(d).add(diff_footprint(x, y)); |
| if (done) { |
| // Reverse path ran over front path. |
| v_map1 = v_map1.subList(0, footsteps.get(footstep) + 1); |
| LinkedList<Diff> a |
| = diff_path1(v_map1, text1.substring(0, text1_length - x), |
| text2.substring(0, text2_length - y)); |
| a.addAll(diff_path2(v_map2, text1.substring(text1_length - x), |
| text2.substring(text2_length - y))); |
| return a; |
| } |
| } |
| } |
| } |
| // Number of diffs equals number of characters, no commonality at all. |
| return null; |
| } |
| |
| |
| /** |
| * Work from the middle back to the start to determine the path. |
| * @param v_map List of path sets. |
| * @param text1 Old string fragment to be diffed. |
| * @param text2 New string fragment to be diffed. |
| * @return LinkedList of Diff objects. |
| */ |
| protected LinkedList<Diff> diff_path1(List<Set<Long>> v_map, |
| String text1, String text2) { |
| LinkedList<Diff> path = new LinkedList<Diff>(); |
| int x = text1.length(); |
| int y = text2.length(); |
| Operation last_op = null; |
| for (int d = v_map.size() - 2; d >= 0; d--) { |
| while (true) { |
| if (v_map.get(d).contains(diff_footprint(x - 1, y))) { |
| x--; |
| if (last_op == Operation.DELETE) { |
| path.getFirst().text = text1.charAt(x) + path.getFirst().text; |
| } else { |
| path.addFirst(new Diff(Operation.DELETE, |
| text1.substring(x, x + 1))); |
| } |
| last_op = Operation.DELETE; |
| break; |
| } else if (v_map.get(d).contains(diff_footprint(x, y - 1))) { |
| y--; |
| if (last_op == Operation.INSERT) { |
| path.getFirst().text = text2.charAt(y) + path.getFirst().text; |
| } else { |
| path.addFirst(new Diff(Operation.INSERT, |
| text2.substring(y, y + 1))); |
| } |
| last_op = Operation.INSERT; |
| break; |
| } else { |
| x--; |
| y--; |
| assert (text1.charAt(x) == text2.charAt(y)) |
| : "No diagonal. Can't happen. (diff_path1)"; |
| if (last_op == Operation.EQUAL) { |
| path.getFirst().text = text1.charAt(x) + path.getFirst().text; |
| } else { |
| path.addFirst(new Diff(Operation.EQUAL, text1.substring(x, x + 1))); |
| } |
| last_op = Operation.EQUAL; |
| } |
| } |
| } |
| return path; |
| } |
| |
| |
| /** |
| * Work from the middle back to the end to determine the path. |
| * @param v_map List of path sets. |
| * @param text1 Old string fragment to be diffed. |
| * @param text2 New string fragment to be diffed. |
| * @return LinkedList of Diff objects. |
| */ |
| protected LinkedList<Diff> diff_path2(List<Set<Long>> v_map, |
| String text1, String text2) { |
| LinkedList<Diff> path = new LinkedList<Diff>(); |
| int x = text1.length(); |
| int y = text2.length(); |
| Operation last_op = null; |
| for (int d = v_map.size() - 2; d >= 0; d--) { |
| while (true) { |
| if (v_map.get(d).contains(diff_footprint(x - 1, y))) { |
| x--; |
| if (last_op == Operation.DELETE) { |
| path.getLast().text += text1.charAt(text1.length() - x - 1); |
| } else { |
| path.addLast(new Diff(Operation.DELETE, |
| text1.substring(text1.length() - x - 1, text1.length() - x))); |
| } |
| last_op = Operation.DELETE; |
| break; |
| } else if (v_map.get(d).contains(diff_footprint(x, y - 1))) { |
| y--; |
| if (last_op == Operation.INSERT) { |
| path.getLast().text += text2.charAt(text2.length() - y - 1); |
| } else { |
| path.addLast(new Diff(Operation.INSERT, |
| text2.substring(text2.length() - y - 1, text2.length() - y))); |
| } |
| last_op = Operation.INSERT; |
| break; |
| } else { |
| x--; |
| y--; |
| assert (text1.charAt(text1.length() - x - 1) |
| == text2.charAt(text2.length() - y - 1)) |
| : "No diagonal. Can't happen. (diff_path2)"; |
| if (last_op == Operation.EQUAL) { |
| path.getLast().text += text1.charAt(text1.length() - x - 1); |
| } else { |
| path.addLast(new Diff(Operation.EQUAL, |
| text1.substring(text1.length() - x - 1, text1.length() - x))); |
| } |
| last_op = Operation.EQUAL; |
| } |
| } |
| } |
| return path; |
| } |
| |
| |
| /** |
| * Compute a good hash of two integers. |
| * @param x First int. |
| * @param y Second int. |
| * @return A long made up of both ints. |
| */ |
| protected long diff_footprint(int x, int y) { |
| // The maximum size for a long is 9,223,372,036,854,775,807 |
| // The maximum size for an int is 2,147,483,647 |
| // Two ints fit nicely in one long. |
| long result = x; |
| result = result << 32; |
| result += y; |
| return result; |
| } |
| |
| |
| /** |
| * 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: 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 diff_commonSuffix(String text1, String text2) { |
| // Performance analysis: http://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.charAt(text1_length - i) != text2.charAt(text2_length - i)) { |
| return i - 1; |
| } |
| } |
| return n; |
| } |
| |
| |
| /** |
| * Do the two texts share a substring which is at least half the length of |
| * the longer text? |
| * @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) { |
| String longtext = text1.length() > text2.length() ? text1 : text2; |
| String shorttext = text1.length() > text2.length() ? text2 : text1; |
| if (longtext.length() < 10 || shorttext.length() < 1) { |
| 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, i + longtext.length() / 4); |
| int j = -1; |
| String best_common = ""; |
| String best_longtext_a = "", best_longtext_b = ""; |
| String best_shorttext_a = "", best_shorttext_b = ""; |
| while ((j = shorttext.indexOf(seed, j + 1)) != -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, j) |
| + shorttext.substring(j, 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() >= longtext.length() / 2) { |
| 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 LinkedList of Diff objects. |
| */ |
| public void diff_cleanupSemantic(LinkedList<Diff> diffs) { |
| if (diffs.isEmpty()) { |
| return; |
| } |
| boolean changes = false; |
| Stack<Diff> equalities = new Stack<Diff>(); // 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 length_changes1 = 0; |
| // Number of characters that changed after the equality. |
| int length_changes2 = 0; |
| Diff thisDiff = pointer.next(); |
| while (thisDiff != null) { |
| if (thisDiff.operation == Operation.EQUAL) { |
| // equality found |
| equalities.push(thisDiff); |
| length_changes1 = length_changes2; |
| length_changes2 = 0; |
| lastequality = thisDiff.text; |
| } else { |
| // an insertion or deletion |
| length_changes2 += thisDiff.text.length(); |
| if (lastequality != null && (lastequality.length() <= length_changes1) |
| && (lastequality.length() <= length_changes2)) { |
| //System.out.println("Splitting: '" + lastequality + "'"); |
| // 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. |
| } |
| } |
| |
| length_changes1 = 0; // Reset the counters. |
| length_changes2 = 0; |
| lastequality = null; |
| changes = true; |
| } |
| } |
| thisDiff = pointer.hasNext() ? pointer.next() : null; |
| } |
| |
| if (changes) { |
| diff_cleanupMerge(diffs); |
| } |
| diff_cleanupSemanticLossless(diffs); |
| } |
| |
| |
| /** |
| * 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 diff_cleanupSemanticLossless(LinkedList<Diff> diffs) { |
| String equality1, edit, equality2; |
| String commonString; |
| int commonOffset; |
| int score, bestScore; |
| String bestEquality1, bestEdit, 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.operation == Operation.EQUAL && |
| nextDiff.operation == Operation.EQUAL) { |
| // This is a single edit surrounded by equalities. |
| equality1 = prevDiff.text; |
| edit = thisDiff.text; |
| equality2 = nextDiff.text; |
| |
| // First, shift the edit as far left as possible. |
| commonOffset = diff_commonSuffix(equality1, edit); |
| if (commonOffset != 0) { |
| 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. |
| bestEquality1 = equality1; |
| bestEdit = edit; |
| bestEquality2 = equality2; |
| bestScore = diff_cleanupSemanticScore(equality1, edit) |
| + diff_cleanupSemanticScore(edit, equality2); |
| while (edit.length() != 0 && equality2.length() != 0 |
| && edit.charAt(0) == equality2.charAt(0)) { |
| equality1 += edit.charAt(0); |
| edit = edit.substring(1) + equality2.charAt(0); |
| equality2 = equality2.substring(1); |
| 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 (!prevDiff.text.equals(bestEquality1)) { |
| // We have an improvement, save it back to the diff. |
| if (bestEquality1.length() != 0) { |
| prevDiff.text = 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.text = bestEdit; |
| if (bestEquality2.length() != 0) { |
| nextDiff.text = 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 5 (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 5; |
| } |
| |
| // 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. |
| int score = 0; |
| // One point for non-alphanumeric. |
| if (!Character.isLetterOrDigit(one.charAt(one.length() - 1)) |
| || !Character.isLetterOrDigit(two.charAt(0))) { |
| score++; |
| // Two points for whitespace. |
| if (Character.isWhitespace(one.charAt(one.length() - 1)) |
| || Character.isWhitespace(two.charAt(0))) { |
| score++; |
| // Three points for line breaks. |
| if (Character.getType(one.charAt(one.length() - 1)) == Character.CONTROL |
| || Character.getType(two.charAt(0)) == Character.CONTROL) { |
| score++; |
| // Four points for blank lines. |
| if (BLANKLINEEND.matcher(one).find() |
| || BLANKLINESTART.matcher(two).find()) { |
| score++; |
| } |
| } |
| } |
| } |
| return score; |
| } |
| |
| |
| private Pattern BLANKLINEEND |
| = Pattern.compile("\\n\\r?\\n\\Z", Pattern.DOTALL); |
| private Pattern BLANKLINESTART |
| = Pattern.compile("\\A\\r?\\n\\r?\\n", Pattern.DOTALL); |
| |
| |
| /** |
| * Reduce the number of edits by eliminating operationally trivial equalities. |
| * @param diffs LinkedList of Diff objects. |
| */ |
| public void diff_cleanupEfficiency(LinkedList<Diff> diffs) { |
| if (diffs.isEmpty()) { |
| return; |
| } |
| boolean changes = false; |
| Stack<Diff> equalities = new Stack<Diff>(); // 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 pre_ins = false; |
| // Is there a deletion operation before the last equality. |
| boolean pre_del = false; |
| // Is there an insertion operation after the last equality. |
| boolean post_ins = false; |
| // Is there a deletion operation after the last equality. |
| boolean post_del = false; |
| Diff thisDiff = pointer.next(); |
| Diff safeDiff = thisDiff; // The last Diff that is known to be unsplitable. |
| while (thisDiff != null) { |
| if (thisDiff.operation == Operation.EQUAL) { |
| // equality found |
| if (thisDiff.text.length() < Diff_EditCost && (post_ins || post_del)) { |
| // Candidate found. |
| equalities.push(thisDiff); |
| pre_ins = post_ins; |
| pre_del = post_del; |
| lastequality = thisDiff.text; |
| } else { |
| // Not a candidate, and can never become one. |
| equalities.clear(); |
| lastequality = null; |
| safeDiff = thisDiff; |
| } |
| post_ins = post_del = false; |
| } else { |
| // an insertion or deletion |
| if (thisDiff.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 != null |
| && ((pre_ins && pre_del && post_ins && post_del) |
| || ((lastequality.length() < Diff_EditCost / 2) |
| && ((pre_ins ? 1 : 0) + (pre_del ? 1 : 0) |
| + (post_ins ? 1 : 0) + (post_del ? 1 : 0)) == 3))) { |
| //System.out.println("Splitting: '" + lastequality + "'"); |
| // 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(thisDiff = new Diff(Operation.INSERT, lastequality)); |
| |
| equalities.pop(); // Throw away the equality we just deleted. |
| lastequality = null; |
| if (pre_ins && pre_del) { |
| // No changes made which could affect previous entry, keep going. |
| post_ins = post_del = 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. |
| } |
| post_ins = post_del = false; |
| } |
| |
| changes = true; |
| } |
| } |
| thisDiff = pointer.hasNext() ? pointer.next() : null; |
| } |
| |
| 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 LinkedList of Diff objects. |
| */ |
| public void diff_cleanupMerge(LinkedList<Diff> diffs) { |
| diffs.add(new Diff(Operation.EQUAL, "")); // Add a dummy entry at the end. |
| ListIterator<Diff> pointer = diffs.listIterator(); |
| int count_delete = 0; |
| int count_insert = 0; |
| String text_delete = ""; |
| String text_insert = ""; |
| Diff thisDiff = pointer.next(); |
| Diff prevEqual = null; |
| int commonlength; |
| while (thisDiff != null) { |
| switch (thisDiff.operation) { |
| case INSERT: |
| count_insert++; |
| text_insert += thisDiff.text; |
| prevEqual = null; |
| break; |
| case DELETE: |
| count_delete++; |
| text_delete += thisDiff.text; |
| prevEqual = null; |
| break; |
| case EQUAL: |
| if (count_delete != 0 || count_insert != 0) { |
| // Delete the offending records. |
| pointer.previous(); // Reverse direction. |
| while (count_delete-- > 0) { |
| pointer.previous(); |
| pointer.remove(); |
| } |
| while (count_insert-- > 0) { |
| pointer.previous(); |
| pointer.remove(); |
| } |
| if (count_delete != 0 && count_insert != 0) { |
| // Factor out any common prefixies. |
| commonlength = diff_commonPrefix(text_insert, text_delete); |
| if (commonlength != 0) { |
| if (pointer.hasPrevious()) { |
| thisDiff = pointer.previous(); |
| assert thisDiff.operation == Operation.EQUAL |
| : "Previous diff should have been an equality."; |
| thisDiff.text += text_insert.substring(0, commonlength); |
| pointer.next(); |
| } else { |
| pointer.add(new Diff(Operation.EQUAL, |
| text_insert.substring(0, commonlength))); |
| } |
| text_insert = text_insert.substring(commonlength); |
| text_delete = text_delete.substring(commonlength); |
| } |
| // Factor out any common suffixies. |
| commonlength = diff_commonSuffix(text_insert, text_delete); |
| if (commonlength != 0) { |
| thisDiff = pointer.next(); |
| thisDiff.text = text_insert.substring(text_insert.length() |
| - commonlength) + thisDiff.text; |
| text_insert = text_insert.substring(0, text_insert.length() |
| - commonlength); |
| text_delete = text_delete.substring(0, text_delete.length() |
| - commonlength); |
| pointer.previous(); |
| } |
| } |
| // Insert the merged records. |
| if (text_delete.length() != 0) { |
| pointer.add(new Diff(Operation.DELETE, text_delete)); |
| } |
| if (text_insert.length() != 0) { |
| pointer.add(new Diff(Operation.INSERT, text_insert)); |
| } |
| // Step forward to the equality. |
| thisDiff = pointer.hasNext() ? pointer.next() : null; |
| } else if (prevEqual != null) { |
| // Merge this equality with the previous one. |
| prevEqual.text += thisDiff.text; |
| pointer.remove(); |
| thisDiff = pointer.previous(); |
| pointer.next(); // Forward direction |
| } |
| count_insert = 0; |
| count_delete = 0; |
| text_delete = ""; |
| text_insert = ""; |
| prevEqual = thisDiff; |
| break; |
| } |
| thisDiff = pointer.hasNext() ? pointer.next() : null; |
| } |
| // System.out.println(diff); |
| if (diffs.getLast().text.length() == 0) { |
| 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.operation == Operation.EQUAL && |
| nextDiff.operation == Operation.EQUAL) { |
| // This is a single edit surrounded by equalities. |
| if (thisDiff.text.endsWith(prevDiff.text)) { |
| // Shift the edit over the previous equality. |
| thisDiff.text = prevDiff.text |
| + thisDiff.text.substring(0, thisDiff.text.length() |
| - prevDiff.text.length()); |
| nextDiff.text = prevDiff.text + nextDiff.text; |
| 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.text.startsWith(nextDiff.text)) { |
| // Shift the edit over the next equality. |
| prevDiff.text += nextDiff.text; |
| thisDiff.text = thisDiff.text.substring(nextDiff.text.length()) |
| + nextDiff.text; |
| 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) { |
| 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 LinkedList of Diff objects. |
| * @param loc Location within text1. |
| * @return Location within text2. |
| */ |
| public int diff_xIndex(LinkedList<Diff> diffs, int loc) { |
| int chars1 = 0; |
| int chars2 = 0; |
| int last_chars1 = 0; |
| int last_chars2 = 0; |
| Diff lastDiff = null; |
| for (Diff aDiff : 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 LinkedList of Diff objects. |
| * @return HTML representation. |
| */ |
| public String diff_prettyHtml(LinkedList<Diff> diffs) { |
| StringBuilder html = new StringBuilder(); |
| int i = 0; |
| for (Diff aDiff : diffs) { |
| String text = aDiff.text.replace("&", "&").replace("<", "<") |
| .replace(">", ">").replace("\n", "¶<BR>"); |
| switch (aDiff.operation) { |
| case INSERT: |
| html.append("<INS STYLE=\"background:#E6FFE6;\" TITLE=\"i=").append(i) |
| .append("\">").append(text).append("</INS>"); |
| break; |
| case DELETE: |
| html.append("<DEL STYLE=\"background:#FFE6E6;\" TITLE=\"i=").append(i) |
| .append("\">").append(text).append("</DEL>"); |
| break; |
| case EQUAL: |
| html.append("<SPAN TITLE=\"i=").append(i).append("\">").append(text) |
| .append("</SPAN>"); |
| break; |
| } |
| if (aDiff.operation != Operation.DELETE) { |
| i += aDiff.text.length(); |
| } |
| } |
| return html.toString(); |
| } |
| |
| |
| /** |
| * Compute and return the source text (all equalities and deletions). |
| * @param diffs LinkedList of Diff objects. |
| * @return Source text. |
| */ |
| public String diff_text1(LinkedList<Diff> diffs) { |
| StringBuilder text = new StringBuilder(); |
| for (Diff aDiff : 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 LinkedList of Diff objects. |
| * @return Destination text. |
| */ |
| public String diff_text2(LinkedList<Diff> diffs) { |
| StringBuilder text = new StringBuilder(); |
| for (Diff aDiff : 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 LinkedList of Diff objects. |
| * @return Number of changes. |
| */ |
| public int diff_levenshtein(LinkedList<Diff> diffs) { |
| int levenshtein = 0; |
| int insertions = 0; |
| int deletions = 0; |
| for (Diff aDiff : diffs) { |
| switch (aDiff.operation) { |
| case INSERT: |
| insertions += aDiff.text.length(); |
| break; |
| case DELETE: |
| deletions += aDiff.text.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 tuples. |
| * @return Delta text. |
| */ |
| public String diff_toDelta(LinkedList<Diff> diffs) { |
| StringBuilder text = new StringBuilder(); |
| for (Diff aDiff : diffs) { |
| switch (aDiff.operation) { |
| case INSERT: |
| try { |
| text.append("+").append(URLEncoder.encode(aDiff.text, "UTF-8") |
| .replace('+', ' ')).append("\t"); |
| } catch (UnsupportedEncodingException e) { |
| // Not likely on modern system. |
| throw new Error("This system does not support UTF-8.", e); |
| } |
| break; |
| case DELETE: |
| text.append("-").append(aDiff.text.length()).append("\t"); |
| break; |
| case 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); |
| delta = 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 tuples or null if invalid. |
| * @throws IllegalArgumentException If invalid input. |
| */ |
| public LinkedList<Diff> diff_fromDelta(String text1, String delta) |
| throws IllegalArgumentException { |
| LinkedList<Diff> diffs = new LinkedList<Diff>(); |
| int pointer = 0; // Cursor in text1 |
| String[] tokens = delta.split("\t"); |
| for (String token : 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.charAt(0)) { |
| case '+': |
| // decode would change all "+" to " " |
| param = param.replace("+", "%2B"); |
| try { |
| param = URLDecoder.decode(param, "UTF-8"); |
| } 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 = 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 { |
| text = text1.substring(pointer, pointer += n); |
| } 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 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. |
| if (text == null || pattern == null) { |
| throw new IllegalArgumentException("Null inputs. (match_main)"); |
| } |
| |
| loc = Math.max(0, Math.min(loc, text.length())); |
| if (text.equals(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, loc + pattern.length()).equals(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. |
| Map<Character, Integer> 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); |
| 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, loc + pattern.length()); |
| 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 Java 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.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 |
| | (((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 Map<Character, Integer> match_alphabet(String pattern) { |
| Map<Character, Integer> s = new HashMap<Character, Integer>(); |
| char[] char_pattern = pattern.toCharArray(); |
| for (char c : char_pattern) { |
| s.put(c, 0); |
| } |
| int i = 0; |
| for (char c : char_pattern) { |
| 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 patch_addContext(Patch patch, String text) { |
| if (text.length() == 0) { |
| return; |
| } |
| String pattern = text.substring(patch.start2, 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) != text.lastIndexOf(pattern) |
| && pattern.length() < Match_MaxBits - Patch_Margin - Patch_Margin) { |
| padding += Patch_Margin; |
| pattern = text.substring(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.substring(Math.max(0, patch.start2 - padding), |
| patch.start2); |
| if (prefix.length() != 0) { |
| patch.diffs.addFirst(new Diff(Operation.EQUAL, prefix)); |
| } |
| // Add the suffix. |
| String suffix = text.substring(patch.start2 + patch.length1, |
| Math.min(text.length(), patch.start2 + patch.length1 + padding)); |
| if (suffix.length() != 0) { |
| patch.diffs.addLast(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 LinkedList of Patch objects. |
| */ |
| public LinkedList<Patch> patch_make(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 = diff_main(text1, text2, true); |
| if (diffs.size() > 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 tuples for text1 to text2. |
| * @return LinkedList of Patch objects. |
| */ |
| public LinkedList<Patch> patch_make(LinkedList<Diff> diffs) { |
| if (diffs == null) { |
| throw new IllegalArgumentException("Null inputs. (patch_make)"); |
| } |
| // 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 tuples for text1 to text2. |
| * @return LinkedList of Patch objects. |
| * @deprecated Prefer patch_make(String text1, LinkedList<Diff> diffs). |
| */ |
| public LinkedList<Patch> patch_make(String text1, String text2, |
| LinkedList<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 tuples for text1 to text2. |
| * @return LinkedList of Patch objects. |
| */ |
| public LinkedList<Patch> patch_make(String text1, LinkedList<Diff> diffs) { |
| if (text1 == null || diffs == null) { |
| throw new IllegalArgumentException("Null inputs. (patch_make)"); |
| } |
| |
| LinkedList<Patch> patches = new LinkedList<Patch>(); |
| if (diffs.isEmpty()) { |
| 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; |
| for (Diff aDiff : diffs) { |
| if (patch.diffs.isEmpty() && aDiff.operation != Operation.EQUAL) { |
| // A new patch starts here. |
| patch.start1 = char_count1; |
| patch.start2 = char_count2; |
| } |
| |
| switch (aDiff.operation) { |
| case INSERT: |
| patch.diffs.add(aDiff); |
| patch.length2 += aDiff.text.length(); |
| postpatch_text = postpatch_text.substring(0, char_count2) |
| + aDiff.text + postpatch_text.substring(char_count2); |
| break; |
| case DELETE: |
| patch.length1 += aDiff.text.length(); |
| patch.diffs.add(aDiff); |
| postpatch_text = postpatch_text.substring(0, char_count2) |
| + postpatch_text.substring(char_count2 + aDiff.text.length()); |
| break; |
| case EQUAL: |
| if (aDiff.text.length() <= 2 * Patch_Margin |
| && !patch.diffs.isEmpty() && aDiff != diffs.getLast()) { |
| // 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.isEmpty()) { |
| patch_addContext(patch, prepatch_text); |
| patches.add(patch); |
| patch = new Patch(); |
| // Unlike Unidiff, our patch lists have a rolling context. |
| // http://code.google.com/p/google-diff-match-patch/wiki/Unidiff |
| // Update prepatch text & pos to reflect the application of the |
| // just completed patch. |
| prepatch_text = postpatch_text; |
| char_count1 = char_count2; |
| } |
| } |
| break; |
| } |
| |
| // Update the current character count. |
| if (aDiff.operation != Operation.INSERT) { |
| char_count1 += aDiff.text.length(); |
| } |
| if (aDiff.operation != Operation.DELETE) { |
| char_count2 += aDiff.text.length(); |
| } |
| } |
| // Pick up the leftover patch if not empty. |
| if (!patch.diffs.isEmpty()) { |
| 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 LinkedList<Patch> patch_deepCopy(LinkedList<Patch> patches) { |
| LinkedList<Patch> patchesCopy = new LinkedList<Patch>(); |
| for (Patch aPatch : patches) { |
| Patch patchCopy = new Patch(); |
| for (Diff aDiff : 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 |
| * boolean values. |
| */ |
| public Object[] patch_apply(LinkedList<Patch> patches, String text) { |
| if (patches.isEmpty()) { |
| return new Object[]{text, new boolean[0]}; |
| } |
| |
| // Deep copy the patches so that no changes are made to originals. |
| patches = patch_deepCopy(patches); |
| |
| String nullPadding = 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; |
| boolean[] results = new boolean[patches.size()]; |
| for (Patch aPatch : 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 = 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.substring(start_loc, |
| Math.min(start_loc + text1.length(), text.length())); |
| } else { |
| text2 = text.substring(start_loc, |
| Math.min(end_loc + this.Match_MaxBits, text.length())); |
| } |
| if (text1.equals(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. |
| LinkedList<Diff> diffs = diff_main(text1, text2, false); |
| if (text1.length() > this.Match_MaxBits |
| && 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; |
| for (Diff aDiff : aPatch.diffs) { |
| if (aDiff.operation != Operation.EQUAL) { |
| int index2 = diff_xIndex(diffs, index1); |
| if (aDiff.operation == Operation.INSERT) { |
| // Insertion |
| text = text.substring(0, start_loc + index2) + aDiff.text |
| + text.substring(start_loc + index2); |
| } else if (aDiff.operation == Operation.DELETE) { |
| // Deletion |
| text = text.substring(0, start_loc + index2) |
| + text.substring(start_loc + diff_xIndex(diffs, |
| index1 + aDiff.text.length())); |
| } |
| } |
| if (aDiff.operation != Operation.DELETE) { |
| index1 += aDiff.text.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 patch_addPadding(LinkedList<Patch> patches) { |
| int paddingLength = this.Patch_Margin; |
| String nullPadding = ""; |
| for (int x = 1; x <= paddingLength; x++) { |
| nullPadding += String.valueOf((char) x); |
| } |
| |
| // Bump all the patches forward. |
| for (Patch aPatch : patches) { |
| aPatch.start1 += paddingLength; |
| aPatch.start2 += paddingLength; |
| } |
| |
| // Add some padding on start of first diff. |
| Patch patch = patches.getFirst(); |
| LinkedList<Diff> diffs = patch.diffs; |
| if (diffs.isEmpty() || diffs.getFirst().operation != Operation.EQUAL) { |
| // Add nullPadding equality. |
| diffs.addFirst(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.getFirst().text.length()) { |
| // Grow first equality. |
| Diff firstDiff = diffs.getFirst(); |
| 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.getLast(); |
| diffs = patch.diffs; |
| if (diffs.isEmpty() || diffs.getLast().operation != Operation.EQUAL) { |
| // Add nullPadding equality. |
| diffs.addLast(new Diff(Operation.EQUAL, nullPadding)); |
| patch.length1 += paddingLength; |
| patch.length2 += paddingLength; |
| } else if (paddingLength > diffs.getLast().text.length()) { |
| // Grow last equality. |
| Diff lastDiff = diffs.getLast(); |
| 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. |
| * @param patches LinkedList of Patch objects. |
| */ |
| public void patch_splitMax(LinkedList<Patch> patches) { |
| int patch_size; |
| String precontext, postcontext; |
| Patch patch; |
| int start1, start2; |
| boolean empty; |
| Operation diff_type; |
| String diff_text; |
| ListIterator<Patch> pointer = patches.listIterator(); |
| Patch bigpatch = pointer.hasNext() ? pointer.next() : null; |
| while (bigpatch != null) { |
| if (bigpatch.length1 <= Match_MaxBits) { |
| bigpatch = pointer.hasNext() ? pointer.next() : null; |
| continue; |
| } |
| // Remove the big old patch. |
| pointer.remove(); |
| patch_size = Match_MaxBits; |
| start1 = bigpatch.start1; |
| start2 = bigpatch.start2; |
| precontext = ""; |
| while (!bigpatch.diffs.isEmpty()) { |
| // Create one of several smaller patches. |
| patch = new Patch(); |
| 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.isEmpty() |
| && patch.length1 < patch_size - Patch_Margin) { |
| diff_type = bigpatch.diffs.getFirst().operation; |
| diff_text = bigpatch.diffs.getFirst().text; |
| if (diff_type == Operation.INSERT) { |
| // Insertions are harmless. |
| patch.length2 += diff_text.length(); |
| start2 += diff_text.length(); |
| patch.diffs.addLast(bigpatch.diffs.removeFirst()); |
| empty = false; |
| } else if (diff_type == Operation.DELETE && patch.diffs.size() == 1 |
| && patch.diffs.getFirst().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.removeFirst(); |
| } 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.equals(bigpatch.diffs.getFirst().text)) { |
| bigpatch.diffs.removeFirst(); |
| } else { |
| bigpatch.diffs.getFirst().text = bigpatch.diffs.getFirst().text |
| .substring(diff_text.length()); |
| } |
| } |
| } |
| // Compute the head context for the next patch. |
| precontext = diff_text2(patch.diffs); |
| precontext = precontext.substring(Math.max(0, precontext.length() |
| - Patch_Margin)); |
| // 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.isEmpty() |
| && patch.diffs.getLast().operation == Operation.EQUAL) { |
| patch.diffs.getLast().text += postcontext; |
| } else { |
| patch.diffs.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 patch_toText(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. |
| * @throws IllegalArgumentException If invalid input. |
| */ |
| public List<Patch> patch_fromText(String textline) |
| throws IllegalArgumentException { |
| List<Patch> patches = new LinkedList<Patch>(); |
| if (textline.length() == 0) { |
| return patches; |
| } |
| List<String> textList = Arrays.asList(textline.split("\n")); |
| LinkedList<String> text = new LinkedList<String>(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.start1 = Integer.parseInt(m.group(1)); |
| if (m.group(2).length() == 0) { |
| patch.start1--; |
| patch.length1 = 1; |
| } else if (m.group(2).equals("0")) { |
| patch.length1 = 0; |
| } else { |
| patch.start1--; |
| patch.length1 = Integer.parseInt(m.group(2)); |
| } |
| |
| patch.start2 = Integer.parseInt(m.group(3)); |
| if (m.group(4).length() == 0) { |
| patch.start2--; |
| patch.length2 = 1; |
| } else if (m.group(4).equals("0")) { |
| patch.length2 = 0; |
| } else { |
| patch.start2--; |
| patch.length2 = Integer.parseInt(m.group(4)); |
| } |
| text.removeFirst(); |
| |
| while (!text.isEmpty()) { |
| try { |
| sign = text.getFirst().charAt(0); |
| } catch (IndexOutOfBoundsException 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, "UTF-8"); |
| } 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 patch_fromText: " + line, e); |
| } |
| 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 IllegalArgumentException( |
| "Invalid patch mode '" + sign + "' in: " + line); |
| } |
| text.removeFirst(); |
| } |
| } |
| return patches; |
| } |
| |
| |
| /** |
| * Class representing one diff operation. |
| */ |
| public static class Diff { |
| /** |
| * One of: INSERT, DELETE or EQUAL. |
| */ |
| public Operation operation; |
| /** |
| * The text associated with this diff operation. |
| */ |
| public String text; |
| |
| /** |
| * 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 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 boolean equals(Object d) { |
| try { |
| return (((Diff) d).operation == this.operation) |
| && (((Diff) d).text.equals(this.text)); |
| } catch (ClassCastException e) { |
| return false; |
| } |
| } |
| } |
| |
| |
| /** |
| * Class representing one patch operation. |
| */ |
| public static class Patch { |
| public LinkedList<Diff> diffs; |
| public int start1; |
| public int start2; |
| public int length1; |
| public int length2; |
| |
| |
| /** |
| * Constructor. Initializes with an empty list of diffs. |
| */ |
| public Patch() { |
| this.diffs = new LinkedList<Diff>(); |
| } |
| |
| |
| /** |
| * Emmulate GNU diff's format. |
| * Header: @@ -382,8 +481,9 @@ |
| * Indicies are printed as 1-based, not 0-based. |
| * @return The GNU diff string. |
| */ |
| public String toString() { |
| String coords1, coords2; |
| if (this.length1 == 0) { |
| coords1 = this.start1 + ",0"; |
| } else if (this.length1 == 1) { |
| coords1 = Integer.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 = Integer.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. |
| for (Diff aDiff : this.diffs) { |
| switch (aDiff.operation) { |
| case INSERT: |
| text.append('+'); |
| break; |
| case DELETE: |
| text.append('-'); |
| break; |
| case EQUAL: |
| text.append(' '); |
| break; |
| } |
| try { |
| text.append(URLEncoder.encode(aDiff.text, "UTF-8").replace('+', ' ')) |
| .append("\n"); |
| } catch (UnsupportedEncodingException e) { |
| // Not likely on modern system. |
| throw new Error("This system does not support UTF-8.", e); |
| } |
| } |
| return unescapeForEncodeUriCompatability(text.toString()); |
| } |
| } |
| |
| |
| /** |
| * Unescape selected chars for compatability with JavaScript's encodeURI. |
| * In speed critical applications this could be dropped since the |
| * receiving application will certainly decode these fine. |
| * Note that this function is case-sensitive. Thus "%3f" would not be |
| * unescaped. But this is ok because it is only called with the output of |
| * URLEncoder.encode which returns uppercase hex. |
| * |
| * Example: "%3F" -> "?", "%24" -> "$", etc. |
| * |
| * @param str The string to escape. |
| * @return The escaped string. |
| */ |
| private static String unescapeForEncodeUriCompatability(String str) { |
| return str.replace("%21", "!").replace("%7E", "~") |
| .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", "#"); |
| } |
| } |