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* 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. */ #include <algorithm> #include <limits> // Code known to compile and run with Qt 4.3 through Qt 4.7. #include <QtCore> #include <time.h> #include "diff_match_patch.h" ////////////////////////// // // Diff Class // ////////////////////////// /** * Constructor. Initializes the diff with the provided values. * @param operation One of INSERT, DELETE or EQUAL * @param text The text being applied */ Diff::Diff(Operation _operation, const QString &_text) : operation(_operation), text(_text) { // Construct a diff with the specified operation and text. } Diff::Diff() { } QString Diff::strOperation(Operation op) { switch (op) { case INSERT: return "INSERT"; case DELETE: return "DELETE"; case EQUAL: return "EQUAL"; } throw "Invalid operation."; } /** * Display a human-readable version of this Diff. * @return text version */ QString Diff::toString() const { QString prettyText = text; // Replace linebreaks with Pilcrow signs. prettyText.replace('\n', L'\u00b6'); return QString("Diff(") + strOperation(operation) + QString(",\"") + prettyText + QString("\")"); } /** * Is this Diff equivalent to another Diff? * @param d Another Diff to compare against * @return true or false */ bool Diff::operator==(const Diff &d) const { return (d.operation == this->operation) && (d.text == this->text); } bool Diff::operator!=(const Diff &d) const { return !(operator == (d)); } ///////////////////////////////////////////// // // Patch Class // ///////////////////////////////////////////// /** * Constructor. Initializes with an empty list of diffs. */ Patch::Patch() : start1(0), start2(0), length1(0), length2(0) { } bool Patch::isNull() const { if (start1 == 0 && start2 == 0 && length1 == 0 && length2 == 0 && diffs.size() == 0) { return true; } return false; } /** * Emulate GNU diff's format. * Header: @@ -382,8 +481,9 @@ * Indices are printed as 1-based, not 0-based. * @return The GNU diff string */ QString Patch::toString() { QString coords1, coords2; if (length1 == 0) { coords1 = QString::number(start1) + QString(",0"); } else if (length1 == 1) { coords1 = QString::number(start1 + 1); } else { coords1 = QString::number(start1 + 1) + QString(",") + QString::number(length1); } if (length2 == 0) { coords2 = QString::number(start2) + QString(",0"); } else if (length2 == 1) { coords2 = QString::number(start2 + 1); } else { coords2 = QString::number(start2 + 1) + QString(",") + QString::number(length2); } QString text; text = QString("@@ -") + coords1 + QString(" +") + coords2 + QString(" @@\n"); // Escape the body of the patch with %xx notation. foreach (Diff aDiff, diffs) { switch (aDiff.operation) { case INSERT: text += QString('+'); break; case DELETE: text += QString('-'); break; case EQUAL: text += QString(' '); break; } text += QString(QUrl::toPercentEncoding(aDiff.text, " !~*'();/?:@&=+$,#")) + QString("\n"); } return text; } ///////////////////////////////////////////// // // diff_match_patch Class // ///////////////////////////////////////////// diff_match_patch::diff_match_patch() : Diff_Timeout(1.0f), Diff_EditCost(4), Match_Threshold(0.5f), Match_Distance(1000), Patch_DeleteThreshold(0.5f), Patch_Margin(4), Match_MaxBits(32) { } QList<Diff> diff_match_patch::diff_main(const QString &text1, const QString &text2) { return diff_main(text1, text2, true); } QList<Diff> diff_match_patch::diff_main(const QString &text1, const QString &text2, bool checklines) { // Set a deadline by which time the diff must be complete. clock_t deadline; if (Diff_Timeout <= 0) { deadline = std::numeric_limits<clock_t>::max(); } else { deadline = clock() + (clock_t)(Diff_Timeout * CLOCKS_PER_SEC); } return diff_main(text1, text2, checklines, deadline); } QList<Diff> diff_match_patch::diff_main(const QString &text1, const QString &text2, bool checklines, clock_t deadline) { // Check for null inputs. if (text1.isNull() || text2.isNull()) { throw "Null inputs. (diff_main)"; } // Check for equality (speedup). QList<Diff> diffs; if (text1 == text2) { if (!text1.isEmpty()) { diffs.append(Diff(EQUAL, text1)); } return diffs; } // Trim off common prefix (speedup). int commonlength = diff_commonPrefix(text1, text2); const QString &commonprefix = text1.left(commonlength); QString textChopped1 = text1.mid(commonlength); QString textChopped2 = text2.mid(commonlength); // Trim off common suffix (speedup). commonlength = diff_commonSuffix(textChopped1, textChopped2); const QString &commonsuffix = textChopped1.right(commonlength); textChopped1 = textChopped1.left(textChopped1.length() - commonlength); textChopped2 = textChopped2.left(textChopped2.length() - commonlength); // Compute the diff on the middle block. diffs = diff_compute(textChopped1, textChopped2, checklines, deadline); // Restore the prefix and suffix. if (!commonprefix.isEmpty()) { diffs.prepend(Diff(EQUAL, commonprefix)); } if (!commonsuffix.isEmpty()) { diffs.append(Diff(EQUAL, commonsuffix)); } diff_cleanupMerge(diffs); return diffs; } QList<Diff> diff_match_patch::diff_compute(QString text1, QString text2, bool checklines, clock_t deadline) { QList<Diff> diffs; if (text1.isEmpty()) { // Just add some text (speedup). diffs.append(Diff(INSERT, text2)); return diffs; } if (text2.isEmpty()) { // Just delete some text (speedup). diffs.append(Diff(DELETE, text1)); return diffs; } { const QString longtext = text1.length() > text2.length() ? text1 : text2; const QString shorttext = text1.length() > text2.length() ? text2 : text1; const int i = longtext.indexOf(shorttext); if (i != -1) { // Shorter text is inside the longer text (speedup). const Operation op = (text1.length() > text2.length()) ? DELETE : INSERT; diffs.append(Diff(op, longtext.left(i))); diffs.append(Diff(EQUAL, shorttext)); diffs.append(Diff(op, safeMid(longtext, i + shorttext.length()))); return diffs; } if (shorttext.length() == 1) { // Single character string. // After the previous speedup, the character can't be an equality. diffs.append(Diff(DELETE, text1)); diffs.append(Diff(INSERT, text2)); return diffs; } // Garbage collect longtext and shorttext by scoping out. } // Check to see if the problem can be split in two. const QStringList hm = diff_halfMatch(text1, text2); if (hm.count() > 0) { // A half-match was found, sort out the return data. const QString text1_a = hm[0]; const QString text1_b = hm[1]; const QString text2_a = hm[2]; const QString text2_b = hm[3]; const QString mid_common = hm[4]; // Send both pairs off for separate processing. const QList<Diff> diffs_a = diff_main(text1_a, text2_a, checklines, deadline); const QList<Diff> diffs_b = diff_main(text1_b, text2_b, checklines, deadline); // Merge the results. diffs = diffs_a; diffs.append(Diff(EQUAL, mid_common)); diffs += diffs_b; return diffs; } // Perform a real diff. if (checklines && text1.length() > 100 && text2.length() > 100) { return diff_lineMode(text1, text2, deadline); } return diff_bisect(text1, text2, deadline); } QList<Diff> diff_match_patch::diff_lineMode(QString text1, QString text2, clock_t deadline) { // Scan the text on a line-by-line basis first. const QList<QVariant> b = diff_linesToChars(text1, text2); text1 = b[0].toString(); text2 = b[1].toString(); QStringList linearray = b[2].toStringList(); QList<Diff> diffs = diff_main(text1, text2, false, deadline); // Convert the diff back to original text. diff_charsToLines(diffs, linearray); // Eliminate freak matches (e.g. blank lines) diff_cleanupSemantic(diffs); // Rediff any replacement blocks, this time character-by-character. // Add a dummy entry at the end. diffs.append(Diff(EQUAL, "")); int count_delete = 0; int count_insert = 0; QString text_delete = ""; QString text_insert = ""; QMutableListIterator<Diff> pointer(diffs); Diff *thisDiff = pointer.hasNext() ? &pointer.next() : NULL; 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(); } foreach(Diff newDiff, diff_main(text_delete, text_insert, false, deadline)) { pointer.insert(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; } QList<Diff> diff_match_patch::diff_bisect(const QString &text1, const QString &text2, clock_t deadline) { // Cache the text lengths to prevent multiple calls. const int text1_length = text1.length(); const int text2_length = text2.length(); const int max_d = (text1_length + text2_length + 1) / 2; const int v_offset = max_d; const int v_length = 2 * max_d; int *v1 = new int[v_length]; int *v2 = new int[v_length]; for (int x = 0; x < v_length; x++) { v1[x] = -1; v2[x] = -1; } v1[v_offset + 1] = 0; v2[v_offset + 1] = 0; const int delta = text1_length - text2_length; // If the total number of characters is odd, then the front path will // collide with the reverse path. const bool front = (delta % 2 != 0); // Offsets for start and end of k loop. // Prevents mapping of space beyond the grid. int k1start = 0; int k1end = 0; int k2start = 0; int k2end = 0; for (int d = 0; d < max_d; d++) { // Bail out if deadline is reached. if (clock() > deadline) { break; } // Walk the front path one step. for (int k1 = -d + k1start; k1 <= d - k1end; k1 += 2) { const int k1_offset = v_offset + k1; int x1; if (k1 == -d || (k1 != d && v1[k1_offset - 1] < v1[k1_offset + 1])) { x1 = v1[k1_offset + 1]; } else { x1 = v1[k1_offset - 1] + 1; } int y1 = x1 - k1; while (x1 < text1_length && y1 < text2_length && text1[x1] == text2[y1]) { x1++; y1++; } v1[k1_offset] = x1; if (x1 > text1_length) { // Ran off the right of the graph. k1end += 2; } else if (y1 > text2_length) { // Ran off the bottom of the graph. k1start += 2; } else if (front) { int k2_offset = v_offset + delta - k1; if (k2_offset >= 0 && k2_offset < v_length && v2[k2_offset] != -1) { // Mirror x2 onto top-left coordinate system. int x2 = text1_length - v2[k2_offset]; if (x1 >= x2) { // Overlap detected. delete [] v1; delete [] v2; return diff_bisectSplit(text1, text2, x1, y1, deadline); } } } } // Walk the reverse path one step. for (int k2 = -d + k2start; k2 <= d - k2end; k2 += 2) { const int k2_offset = v_offset + k2; int x2; if (k2 == -d || (k2 != d && v2[k2_offset - 1] < v2[k2_offset + 1])) { x2 = v2[k2_offset + 1]; } else { x2 = v2[k2_offset - 1] + 1; } int y2 = x2 - k2; while (x2 < text1_length && y2 < text2_length && text1[text1_length - x2 - 1] == text2[text2_length - y2 - 1]) { x2++; y2++; } v2[k2_offset] = x2; if (x2 > text1_length) { // Ran off the left of the graph. k2end += 2; } else if (y2 > text2_length) { // Ran off the top of the graph. k2start += 2; } else if (!front) { int k1_offset = v_offset + delta - k2; if (k1_offset >= 0 && k1_offset < v_length && v1[k1_offset] != -1) { int x1 = v1[k1_offset]; int y1 = v_offset + x1 - k1_offset; // Mirror x2 onto top-left coordinate system. x2 = text1_length - x2; if (x1 >= x2) { // Overlap detected. delete [] v1; delete [] v2; return diff_bisectSplit(text1, text2, x1, y1, deadline); } } } } } delete [] v1; delete [] v2; // Diff took too long and hit the deadline or // number of diffs equals number of characters, no commonality at all. QList<Diff> diffs; diffs.append(Diff(DELETE, text1)); diffs.append(Diff(INSERT, text2)); return diffs; } QList<Diff> diff_match_patch::diff_bisectSplit(const QString &text1, const QString &text2, int x, int y, clock_t deadline) { QString text1a = text1.left(x); QString text2a = text2.left(y); QString text1b = safeMid(text1, x); QString text2b = safeMid(text2, y); // Compute both diffs serially. QList<Diff> diffs = diff_main(text1a, text2a, false, deadline); QList<Diff> diffsb = diff_main(text1b, text2b, false, deadline); return diffs + diffsb; } QList<QVariant> diff_match_patch::diff_linesToChars(const QString &text1, const QString &text2) { QStringList lineArray; QMap<QString, int> lineHash; // 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.append(""); const QString chars1 = diff_linesToCharsMunge(text1, lineArray, lineHash); const QString chars2 = diff_linesToCharsMunge(text2, lineArray, lineHash); QList<QVariant> listRet; listRet.append(QVariant::fromValue(chars1)); listRet.append(QVariant::fromValue(chars2)); listRet.append(QVariant::fromValue(lineArray)); return listRet; } QString diff_match_patch::diff_linesToCharsMunge(const QString &text, QStringList &lineArray, QMap<QString, int> &lineHash) { int lineStart = 0; int lineEnd = -1; QString line; QString chars; // 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 = safeMid(text, lineStart, lineEnd + 1 - lineStart); lineStart = lineEnd + 1; if (lineHash.contains(line)) { chars += QChar(static_cast<ushort>(lineHash.value(line))); } else { lineArray.append(line); lineHash.insert(line, lineArray.size() - 1); chars += QChar(static_cast<ushort>(lineArray.size() - 1)); } } return chars; } void diff_match_patch::diff_charsToLines(QList<Diff> &diffs, const QStringList &lineArray) { // Qt has no mutable foreach construct. QMutableListIterator<Diff> i(diffs); while (i.hasNext()) { Diff &diff = i.next(); QString text; for (int y = 0; y < diff.text.length(); y++) { text += lineArray.value(static_cast<ushort>(diff.text[y].unicode())); } diff.text = text; } } int diff_match_patch::diff_commonPrefix(const QString &text1, const QString &text2) { // Performance analysis: http://neil.fraser.name/news/2007/10/09/ const int n = std::min(text1.length(), text2.length()); for (int i = 0; i < n; i++) { if (text1[i] != text2[i]) { return i; } } return n; } int diff_match_patch::diff_commonSuffix(const QString &text1, const QString &text2) { // Performance analysis: http://neil.fraser.name/news/2007/10/09/ const int text1_length = text1.length(); const int text2_length = text2.length(); const int n = std::min(text1_length, text2_length); for (int i = 1; i <= n; i++) { if (text1[text1_length - i] != text2[text2_length - i]) { return i - 1; } } return n; } int diff_match_patch::diff_commonOverlap(const QString &text1, const QString &text2) { // Cache the text lengths to prevent multiple calls. const int text1_length = text1.length(); const int text2_length = text2.length(); // Eliminate the null case. if (text1_length == 0 || text2_length == 0) { return 0; } // Truncate the longer string. QString text1_trunc = text1; QString text2_trunc = text2; if (text1_length > text2_length) { text1_trunc = text1.right(text2_length); } else if (text1_length < text2_length) { text2_trunc = text2.left(text1_length); } const int text_length = std::min(text1_length, text2_length); // Quick check for the worst case. if (text1_trunc == text2_trunc) { return text_length; } // 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) { QString pattern = text1_trunc.right(length); int found = text2_trunc.indexOf(pattern); if (found == -1) { return best; } length += found; if (found == 0 || text1_trunc.right(length) == text2_trunc.left(length)) { best = length; length++; } } } QStringList diff_match_patch::diff_halfMatch(const QString &text1, const QString &text2) { if (Diff_Timeout <= 0) { // Don't risk returning a non-optimal diff if we have unlimited time. return QStringList(); } const QString longtext = text1.length() > text2.length() ? text1 : text2; const QString shorttext = text1.length() > text2.length() ? text2 : text1; if (longtext.length() < 4 || shorttext.length() * 2 < longtext.length()) { return QStringList(); // Pointless. } // First check if the second quarter is the seed for a half-match. const QStringList hm1 = diff_halfMatchI(longtext, shorttext, (longtext.length() + 3) / 4); // Check again based on the third quarter. const QStringList hm2 = diff_halfMatchI(longtext, shorttext, (longtext.length() + 1) / 2); QStringList hm; if (hm1.isEmpty() && hm2.isEmpty()) { return QStringList(); } else if (hm2.isEmpty()) { hm = hm1; } else if (hm1.isEmpty()) { 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 { QStringList listRet; listRet << hm[2] << hm[3] << hm[0] << hm[1] << hm[4]; return listRet; } } QStringList diff_match_patch::diff_halfMatchI(const QString &longtext, const QString &shorttext, int i) { // Start with a 1/4 length substring at position i as a seed. const QString seed = safeMid(longtext, i, longtext.length() / 4); int j = -1; QString best_common; QString best_longtext_a, best_longtext_b; QString best_shorttext_a, best_shorttext_b; while ((j = shorttext.indexOf(seed, j + 1)) != -1) { const int prefixLength = diff_commonPrefix(safeMid(longtext, i), safeMid(shorttext, j)); const int suffixLength = diff_commonSuffix(longtext.left(i), shorttext.left(j)); if (best_common.length() < suffixLength + prefixLength) { best_common = safeMid(shorttext, j - suffixLength, suffixLength) + safeMid(shorttext, j, prefixLength); best_longtext_a = longtext.left(i - suffixLength); best_longtext_b = safeMid(longtext, i + prefixLength); best_shorttext_a = shorttext.left(j - suffixLength); best_shorttext_b = safeMid(shorttext, j + prefixLength); } } if (best_common.length() * 2 >= longtext.length()) { QStringList listRet; listRet << best_longtext_a << best_longtext_b << best_shorttext_a << best_shorttext_b << best_common; return listRet; } else { return QStringList(); } } void diff_match_patch::diff_cleanupSemantic(QList<Diff> &diffs) { if (diffs.isEmpty()) { return; } bool changes = false; QStack<Diff> equalities; // Stack of equalities. QString lastequality; // Always equal to equalities.lastElement().text QMutableListIterator<Diff> pointer(diffs); // Number of characters that changed prior to the equality. int length_insertions1 = 0; int length_deletions1 = 0; // Number of characters that changed after the equality. int length_insertions2 = 0; int length_deletions2 = 0; Diff *thisDiff = pointer.hasNext() ? &pointer.next() : NULL; while (thisDiff != NULL) { if (thisDiff->operation == EQUAL) { // Equality found. equalities.push(*thisDiff); length_insertions1 = length_insertions2; length_deletions1 = length_deletions2; length_insertions2 = 0; length_deletions2 = 0; lastequality = thisDiff->text; } else { // An insertion or deletion. if (thisDiff->operation == INSERT) { length_insertions2 += thisDiff->text.length(); } else { length_deletions2 += thisDiff->text.length(); } // Eliminate an equality that is smaller or equal to the edits on both // sides of it. if (!lastequality.isNull() && (lastequality.length() <= std::max(length_insertions1, length_deletions1)) && (lastequality.length() <= std::max(length_insertions2, length_deletions2))) { // printf("Splitting: '%s'\n", qPrintable(lastequality)); // Walk back to offending equality. while (*thisDiff != equalities.top()) { thisDiff = &pointer.previous(); } pointer.next(); // Replace equality with a delete. pointer.setValue(Diff(DELETE, lastequality)); // Insert a corresponding an insert. pointer.insert(Diff(INSERT, lastequality)); equalities.pop(); // Throw away the equality we just deleted. if (!equalities.isEmpty()) { // Throw away the previous equality (it needs to be reevaluated). equalities.pop(); } if (equalities.isEmpty()) { // 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.top(); while (*thisDiff != pointer.previous()) { // Intentionally empty loop. } } length_insertions1 = 0; // Reset the counters. length_deletions1 = 0; length_insertions2 = 0; length_deletions2 = 0; lastequality = QString(); changes = true; } } thisDiff = pointer.hasNext() ? &pointer.next() : NULL; } // Normalize the diff. if (changes) { diff_cleanupMerge(diffs); } diff_cleanupSemanticLossless(diffs); // Find any overlaps between deletions and insertions. // e.g: <del>abcxxx</del><ins>xxxdef</ins> // -> <del>abc</del>xxx<ins>def</ins> // e.g: <del>xxxabc</del><ins>defxxx</ins> // -> <ins>def</ins>xxx<del>abc</del> // Only extract an overlap if it is as big as the edit ahead or behind it. pointer.toFront(); Diff *prevDiff = NULL; thisDiff = NULL; if (pointer.hasNext()) { prevDiff = &pointer.next(); if (pointer.hasNext()) { thisDiff = &pointer.next(); } } while (thisDiff != NULL) { if (prevDiff->operation == DELETE && thisDiff->operation == INSERT) { QString deletion = prevDiff->text; QString insertion = thisDiff->text; int overlap_length1 = diff_commonOverlap(deletion, insertion); int overlap_length2 = diff_commonOverlap(insertion, deletion); if (overlap_length1 >= overlap_length2) { if (overlap_length1 >= deletion.length() / 2.0 || overlap_length1 >= insertion.length() / 2.0) { // Overlap found. Insert an equality and trim the surrounding edits. pointer.previous(); pointer.insert(Diff(EQUAL, insertion.left(overlap_length1))); prevDiff->text = deletion.left(deletion.length() - overlap_length1); thisDiff->text = safeMid(insertion, overlap_length1); // pointer.insert inserts the element before the cursor, so there is // no need to step past the new element. } } else { if (overlap_length2 >= deletion.length() / 2.0 || overlap_length2 >= insertion.length() / 2.0) { // Reverse overlap found. // Insert an equality and swap and trim the surrounding edits. pointer.previous(); pointer.insert(Diff(EQUAL, deletion.left(overlap_length2))); prevDiff->operation = INSERT; prevDiff->text = insertion.left(insertion.length() - overlap_length2); thisDiff->operation = DELETE; thisDiff->text = safeMid(deletion, overlap_length2); // pointer.insert 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; } } void diff_match_patch::diff_cleanupSemanticLossless(QList<Diff> &diffs) { QString equality1, edit, equality2; QString commonString; int commonOffset; int score, bestScore; QString bestEquality1, bestEdit, bestEquality2; // Create a new iterator at the start. QMutableListIterator<Diff> pointer(diffs); 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 == EQUAL && nextDiff->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 = safeMid(edit, edit.length() - commonOffset); equality1 = equality1.left(equality1.length() - commonOffset); edit = commonString + edit.left(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.isEmpty() && !equality2.isEmpty() && edit[0] == equality2[0]) { equality1 += edit[0]; edit = safeMid(edit, 1) + equality2[0]; equality2 = safeMid(equality2, 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 != bestEquality1) { // We have an improvement, save it back to the diff. if (!bestEquality1.isEmpty()) { 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.isEmpty()) { nextDiff->text = bestEquality2; } else { pointer.remove(); // Delete nextDiff. nextDiff = thisDiff; thisDiff = prevDiff; } } } prevDiff = thisDiff; thisDiff = nextDiff; nextDiff = pointer.hasNext() ? &pointer.next() : NULL; } } int diff_match_patch::diff_cleanupSemanticScore(const QString &one, const QString &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. QChar char1 = one[one.length() - 1]; QChar char2 = two[0]; bool nonAlphaNumeric1 = !char1.isLetterOrNumber(); bool nonAlphaNumeric2 = !char2.isLetterOrNumber(); bool whitespace1 = nonAlphaNumeric1 && char1.isSpace(); bool whitespace2 = nonAlphaNumeric2 && char2.isSpace(); bool lineBreak1 = whitespace1 && char1.category() == QChar::Other_Control; bool lineBreak2 = whitespace2 && char2.category() == QChar::Other_Control; bool blankLine1 = lineBreak1 && BLANKLINEEND.indexIn(one) != -1; bool blankLine2 = lineBreak2 && BLANKLINESTART.indexIn(two) != -1; if (blankLine1 || blankLine2) { // Five points for blank lines. return 5; } else if (lineBreak1 || lineBreak2) { // Four points for line breaks. return 4; } else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) { // Three points for end of sentences. return 3; } else if (whitespace1 || whitespace2) { // Two points for whitespace. return 2; } else if (nonAlphaNumeric1 || nonAlphaNumeric2) { // One point for non-alphanumeric. return 1; } return 0; } // Define some regex patterns for matching boundaries. QRegExp diff_match_patch::BLANKLINEEND = QRegExp("\\n\\r?\\n$"); QRegExp diff_match_patch::BLANKLINESTART = QRegExp("^\\r?\\n\\r?\\n"); void diff_match_patch::diff_cleanupEfficiency(QList<Diff> &diffs) { if (diffs.isEmpty()) { return; } bool changes = false; QStack<Diff> equalities; // Stack of equalities. QString lastequality; // Always equal to equalities.lastElement().text QMutableListIterator<Diff> pointer(diffs); // Is there an insertion operation before the last equality. bool pre_ins = false; // Is there a deletion operation before the last equality. bool pre_del = false; // Is there an insertion operation after the last equality. bool post_ins = false; // Is there a deletion operation after the last equality. bool post_del = false; |
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