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diff_match_patch.h
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diff_match_patch.h
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/*
* Copyright 2008 Google Inc. All Rights Reserved.
* Author: [email protected] (Neil Fraser)
* Author: [email protected] (Mike Slemmer)
*
* 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.
*
* Diff Match and Patch
* http://code.google.com/p/google-diff-match-patch/
*/
#ifndef DIFF_MATCH_PATCH_H
#define DIFF_MATCH_PATCH_H
/*
* 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 [email protected] (Neil Fraser)
*
* Qt/C++ port by [email protected] (Mike Slemmer):
*
* Code known to compile and run with Qt 4.3 through Qt 4.7.
*
* Here is a trivial sample program which works properly when linked with this
* library:
*
#include <QtCore>
#include <QString>
#include <QList>
#include <QMap>
#include <QVariant>
#include "diff_match_patch.h"
int main(int argc, char **argv) {
diff_match_patch dmp;
QString str1 = QString("First string in diff");
QString str2 = QString("Second string in diff");
QString strPatch = dmp.patch_toText(dmp.patch_make(str1, str2));
QPair<QString, QVector<bool> > out
= dmp.patch_apply(dmp.patch_fromText(strPatch), str1);
QString strResult = out.first;
// here, strResult will equal str2 above.
return 0;
}
*/
/**-
* 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."
*/
enum Operation {
DELETE, INSERT, EQUAL
};
/**
* Class representing one diff operation.
*/
class Diff {
public:
Operation operation;
// One of: INSERT, DELETE or EQUAL.
QString text;
// The text associated with this diff operation.
/**
* Constructor. Initializes the diff with the provided values.
* @param operation One of INSERT, DELETE or EQUAL.
* @param text The text being applied.
*/
Diff(Operation _operation, const QString &_text);
Diff();
inline bool isNull() const;
QString toString() const;
bool operator==(const Diff &d) const;
bool operator!=(const Diff &d) const;
static QString strOperation(Operation op);
};
/**
* Class representing one patch operation.
*/
class Patch {
public:
QList<Diff> diffs;
int start1;
int start2;
int length1;
int length2;
/**
* Constructor. Initializes with an empty list of diffs.
*/
Patch();
bool isNull() const;
QString toString();
};
/**
* Class containing the diff, match and patch methods.
* Also contains the behaviour settings.
*/
class diff_match_patch {
friend class diff_match_patch_test;
public:
// 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).
float Diff_Timeout;
// Cost of an empty edit operation in terms of edit characters.
short Diff_EditCost;
// At what point is no match declared (0.0 = perfection, 1.0 = very loose).
float Match_Threshold;
// 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).
int Match_Distance;
// 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.
float Patch_DeleteThreshold;
// Chunk size for context length.
short Patch_Margin;
// The number of bits in an int.
short Match_MaxBits;
private:
// Define some regex patterns for matching boundaries.
static QRegExp BLANKLINEEND;
static QRegExp BLANKLINESTART;
public:
diff_match_patch();
// DIFF FUNCTIONS
/**
* Find the differences between two texts.
* Run a faster slightly less optimal diff.
* This method allows the 'checklines' of diff_main() to be optional.
* Most of the time checklines is wanted, so default to true.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @return Linked List of Diff objects.
*/
QList<Diff> diff_main(const QString &text1, const QString &text2);
/**
* Find the differences between two texts.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @return Linked List of Diff objects.
*/
QList<Diff> diff_main(const QString &text1, const QString &text2, bool checklines);
/**
* Find the differences between two texts. Simplifies the problem by
* stripping any common prefix or suffix off the texts before diffing.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @param deadline Time when the diff should be complete by. Used
* internally for recursive calls. Users should set DiffTimeout instead.
* @return Linked List of Diff objects.
*/
private:
QList<Diff> diff_main(const QString &text1, const QString &text2, bool checklines, clock_t deadline);
/**
* Find the differences between two texts. Assumes that the texts do not
* have any common prefix or suffix.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @param deadline Time when the diff should be complete by.
* @return Linked List of Diff objects.
*/
private:
QList<Diff> diff_compute(QString text1, QString text2, bool checklines, clock_t deadline);
/**
* Do a quick line-level diff on both strings, then rediff the parts for
* greater accuracy.
* This speedup can produce non-minimal diffs.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param deadline Time when the diff should be complete by.
* @return Linked List of Diff objects.
*/
private:
QList<Diff> diff_lineMode(QString text1, QString text2, clock_t deadline);
/**
* Find the 'middle snake' of a diff, split the problem in two
* and return the recursively constructed diff.
* See Myers 1986 paper: An O(ND) Difference Algorithm and Its Variations.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @return Linked List of Diff objects.
*/
protected:
QList<Diff> diff_bisect(const QString &text1, const QString &text2, clock_t deadline);
/**
* Given the location of the 'middle snake', split the diff in two parts
* and recurse.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param x Index of split point in text1.
* @param y Index of split point in text2.
* @param deadline Time at which to bail if not yet complete.
* @return LinkedList of Diff objects.
*/
private:
QList<Diff> diff_bisectSplit(const QString &text1, const QString &text2, int x, int y, clock_t deadline);
/**
* Split two texts into a list of strings. Reduce the texts to a string of
* hashes where each Unicode character represents one line.
* @param text1 First string.
* @param text2 Second string.
* @return Three element Object array, containing the encoded text1, the
* encoded text2 and the List of unique strings. The zeroth element
* of the List of unique strings is intentionally blank.
*/
public:
QList<QVariant> diff_linesToChars(const QString &text1, const QString &text2); // return elems 0 and 1 are QString, elem 2 is QStringList
/**
* 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:
QString diff_linesToCharsMunge(const QString &text, QStringList &lineArray,
QMap<QString, int> &lineHash);
/**
* 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.
*/
public:
void diff_charsToLines(QList<Diff> &diffs, const QStringList &lineArray);
/**
* 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(const QString &text1, const QString &text2);
/**
* 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(const QString &text1, const QString &text2);
/**
* Determine if the suffix of one string is the prefix of another.
* @param text1 First string.
* @param text2 Second string.
* @return The number of characters common to the end of the first
* string and the start of the second string.
*/
protected:
int diff_commonOverlap(const QString &text1, const QString &text2);
/**
* Do the two texts share a substring which is at least half the length of
* the longer text?
* This speedup can produce non-minimal diffs.
* @param text1 First string.
* @param text2 Second string.
* @return Five element String array, containing the prefix of text1, the
* suffix of text1, the prefix of text2, the suffix of text2 and the
* common middle. Or null if there was no match.
*/
protected:
QStringList diff_halfMatch(const QString &text1, const QString &text2);
/**
* 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:
QStringList diff_halfMatchI(const QString &longtext, const QString &shorttext, int i);
/**
* Reduce the number of edits by eliminating semantically trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public:
void diff_cleanupSemantic(QList<Diff> &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(QList<Diff> &diffs);
/**
* Given two strings, compute a score representing whether the internal
* boundary falls on logical boundaries.
* Scores range from 6 (best) to 0 (worst).
* @param one First string.
* @param two Second string.
* @return The score.
*/
private:
int diff_cleanupSemanticScore(const QString &one, const QString &two);
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public:
void diff_cleanupEfficiency(QList<Diff> &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(QList<Diff> &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(const QList<Diff> &diffs, int loc);
/**
* Convert a Diff list into a pretty HTML report.
* @param diffs LinkedList of Diff objects.
* @return HTML representation.
*/
public:
QString diff_prettyHtml(const QList<Diff> &diffs);
/**
* Compute and return the source text (all equalities and deletions).
* @param diffs LinkedList of Diff objects.
* @return Source text.
*/
public:
QString diff_text1(const QList<Diff> &diffs);
/**
* Compute and return the destination text (all equalities and insertions).
* @param diffs LinkedList of Diff objects.
* @return Destination text.
*/
public:
QString diff_text2(const QList<Diff> &diffs);
/**
* 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(const QList<Diff> &diffs);
/**
* 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:
QString diff_toDelta(const QList<Diff> &diffs);
/**
* 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 QString If invalid input.
*/
public:
QList<Diff> diff_fromDelta(const QString &text1, const QString &delta);
// 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(const QString &text, const QString &pattern, int 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(const QString &text, const QString &pattern, int 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, const QString &pattern);
/**
* Initialise the alphabet for the Bitap algorithm.
* @param pattern The text to encode.
* @return Hash of character locations.
*/
protected:
QMap<QChar, int> match_alphabet(const QString &pattern);
// 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, const QString &text);
/**
* 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:
QList<Patch> patch_make(const QString &text1, const QString &text2);
/**
* 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:
QList<Patch> patch_make(const QList<Diff> &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(const QString &text1, const QList<Diff> &diffs).
*/
public:
QList<Patch> patch_make(const QString &text1, const QString &text2, const QList<Diff> &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:
QList<Patch> patch_make(const QString &text1, const QList<Diff> &diffs);
/**
* Given an array of patches, return another array that is identical.
* @param patches Array of patch objects.
* @return Array of patch objects.
*/
public:
QList<Patch> patch_deepCopy(QList<Patch> &patches);
/**
* 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:
QPair<QString,QVector<bool> > patch_apply(QList<Patch> &patches, const QString &text);
/**
* 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:
QString patch_addPadding(QList<Patch> &patches);
/**
* Look through the patches and break up any which are longer than the
* maximum limit of the match algorithm.
* Intended to be called only from within patch_apply.
* @param patches LinkedList of Patch objects.
*/
public:
void patch_splitMax(QList<Patch> &patches);
/**
* Take a list of patches and return a textual representation.
* @param patches List of Patch objects.
* @return Text representation of patches.
*/
public:
QString patch_toText(const QList<Patch> &patches);
/**
* 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 QString If invalid input.
*/
public:
QList<Patch> patch_fromText(const QString &textline);
/**
* A safer version of QString.mid(pos). This one returns "" instead of
* null when the postion equals the string length.
* @param str String to take a substring from.
* @param pos Position to start the substring from.
* @return Substring.
*/
private:
static inline QString safeMid(const QString &str, int pos) {
return (pos == str.length()) ? QString("") : str.mid(pos);
}
/**
* A safer version of QString.mid(pos, len). This one returns "" instead of
* null when the postion equals the string length.
* @param str String to take a substring from.
* @param pos Position to start the substring from.
* @param len Length of substring.
* @return Substring.
*/
private:
static inline QString safeMid(const QString &str, int pos, int len) {
return (pos == str.length()) ? QString("") : str.mid(pos, len);
}
};
#endif // DIFF_MATCH_PATCH_H