Revision ac4b68fbf45853ba4b9e327cb42f93f42a8fa252 authored by Ellie Shin on 17 March 2023, 04:14:20 UTC, committed by Ellie Shin on 17 March 2023, 04:14:20 UTC
1 parent f2c68fb
Diff.h
/*
* Copyright 2008 Google Inc. All Rights Reserved.
* Author: fraser@google.com (Neil Fraser)
* Author: mikeslemmer@gmail.com (Mike Slemmer)
* Author: snhere@gmail.com (Sergey Nozhenko)
*
* 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
#include <limits>
#include <list>
#include <map>
#include <string>
#include <vector>
#include <algorithm>
#include <cstdlib>
#include <cwchar>
#include <time.h>
#include "llvm/Support/ErrorHandling.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 fraser@google.com (Neil Fraser)
*
* Qt/C++ port by mikeslemmer@gmail.com (Mike Slemmer)
*
* STL-only port by snhere@gmail.com (Sergey Nozhenko)
* and some tweaks for std::string by leutloff@sundancer.oche.de (Christian Leutloff)
*
* Here is a trivial sample program:
*
#include "diff_match_patch.h"
#include <string>
using namespace std;
int main(int argc, char **argv) {
diff_match_patch<wstring> dmp;
wstring str1 = L"First string in diff";
wstring str2 = L"Second string in diff";
wstring strPatch = dmp.patch_toText(dmp.patch_make(str1, str2));
pair<wstring, vector<bool> > out
= dmp.patch_apply(dmp.patch_fromText(strPatch), str1);
wstring strResult = out.first;
// here, strResult will equal str2 above.
return 0;
}
*/
// Character type dependencies
template <class char_t> struct diff_match_patch_traits {};
/**
* Class containing the diff, match and patch methods.
* Also contains the behaviour settings.
*/
template <class stringT, class traits = diff_match_patch_traits<typename stringT::value_type> >
class diff_match_patch {
public:
/**
* String and character types
*/
typedef stringT string_t;
typedef typename string_t::value_type char_t;
/**-
* 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.
string_t 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 string_t &_text) : operation(_operation), text(_text) {}
Diff() {}
/**
* Display a human-readable version of this Diff.
* @return text version.
*/
string_t toString() const {
string_t prettyText = text;
// Replace linebreaks with Pilcrow signs.
for (typename string_t::iterator i = prettyText.begin(); i != prettyText.end(); ++i)
if (traits::to_wchar(*i) == L'\n') *i = traits::from_wchar(L'\u00b6');
return traits::cs(L"Diff(") + strOperation(operation) + traits::cs(L",\"") + prettyText + traits::cs(L"\")");
}
/**
* Is this Diff equivalent to another Diff?
* @param d Another Diff to compare against
* @return true or false
*/
bool operator==(const Diff &d) const {
return (d.operation == this->operation) && (d.text == this->text);
}
bool operator!=(const Diff &d) const { return !(operator == (d)); }
static string_t strOperation(Operation op) {
switch (op) {
case INSERT:
return traits::cs(L"INSERT");
case DELETE:
return traits::cs(L"DELETE");
case EQUAL:
return traits::cs(L"EQUAL");
}
llvm_unreachable("Invalid operation.");
}
};
typedef std::list<Diff> Diffs;
/**
* Class representing one patch operation.
*/
class Patch {
public:
Diffs diffs;
int start1;
int start2;
int length1;
int length2;
/**
* Constructor. Initializes with an empty list of diffs.
*/
Patch() : start1(0), start2(0), length1(0), length2(0) {}
bool isNull() const {
return start1 == 0 && start2 == 0 && length1 == 0 && length2 == 0 && diffs.empty();
}
/**
* Emulate GNU diff's format.
* Header: @@ -382,8 +481,9 @@
* Indices are printed as 1-based, not 0-based.
* @return The GNU diff string
*/
string_t toString() const {
string_t coords1, coords2;
if (length1 == 0) {
coords1 = to_string(start1) + traits::cs(L",0");
} else if (length1 == 1) {
coords1 = to_string(start1 + 1);
} else {
coords1 = to_string(start1 + 1) + traits::from_wchar(L',') + to_string(length1);
}
if (length2 == 0) {
coords2 = to_string(start2) + traits::cs(L",0");
} else if (length2 == 1) {
coords2 = to_string(start2 + 1);
} else {
coords2 = to_string(start2 + 1) + traits::from_wchar(L',') + to_string(length2);
}
string_t text(traits::cs(L"@@ -") + coords1 + traits::cs(L" +") + coords2 + traits::cs(L" @@\n"));
// Escape the body of the patch with %xx notation.
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
switch ((*cur_diff).operation) {
case INSERT:
text += traits::from_wchar(L'+');
break;
case DELETE:
text += traits::from_wchar(L'-');
break;
case EQUAL:
text += traits::from_wchar(L' ');
break;
}
append_percent_encoded(text, (*cur_diff).text);
text += traits::from_wchar(L'\n');
}
return text;
}
};
typedef std::list<Patch> Patches;
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;
public:
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) {
}
// DIFF FUNCTIONS
/**
* 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.
* Most of the time checklines is wanted, so default to true.
* @return Linked List of Diff objects.
*/
Diffs diff_main(const string_t &text1, const string_t &text2, bool checklines = true) const {
// 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);
}
Diffs diffs;
diff_main(text1, text2, checklines, deadline, diffs);
return diffs;
}
/**
* 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.
* @param diffs Linked List of Diff objects.
*/
private:
static void diff_main(const string_t &text1, const string_t &text2, bool checklines, clock_t deadline, Diffs& diffs) {
diffs.clear();
// Check for equality (speedup).
if (text1 == text2) {
if (!text1.empty()) {
diffs.push_back(Diff(EQUAL, text1));
}
}
else {
// Trim off common prefix (speedup).
int commonlength = diff_commonPrefix(text1, text2);
const string_t &commonprefix = text1.substr(0, commonlength);
string_t textChopped1 = text1.substr(commonlength);
string_t textChopped2 = text2.substr(commonlength);
// Trim off common suffix (speedup).
commonlength = diff_commonSuffix(textChopped1, textChopped2);
const string_t &commonsuffix = right(textChopped1, commonlength);
textChopped1 = textChopped1.substr(0, textChopped1.length() - commonlength);
textChopped2 = textChopped2.substr(0, textChopped2.length() - commonlength);
// Compute the diff on the middle block.
diff_compute(textChopped1, textChopped2, checklines, deadline, diffs);
// Restore the prefix and suffix.
if (!commonprefix.empty()) {
diffs.push_front(Diff(EQUAL, commonprefix));
}
if (!commonsuffix.empty()) {
diffs.push_back(Diff(EQUAL, commonsuffix));
}
diff_cleanupMerge(diffs);
}
}
/**
* Find the differences between two texts. Assumes that the texts do not
* have any common prefix or suffix.
* @param text1 Old string to be diffed.
* @param text2 New string to be diffed.
* @param checklines Speedup flag. If false, then don't run a
* line-level diff first to identify the changed areas.
* If true, then run a faster slightly less optimal diff.
* @param deadline Time when the diff should be complete by.
* @param diffs Linked List of Diff objects.
*/
private:
static void diff_compute(string_t text1, string_t text2, bool checklines, clock_t deadline, Diffs& diffs) {
if (text1.empty()) {
// Just add some text (speedup).
diffs.push_back(Diff(INSERT, text2));
return;
}
if (text2.empty()) {
// Just delete some text (speedup).
diffs.push_back(Diff(DELETE, text1));
return;
}
{
const string_t& longtext = text1.length() > text2.length() ? text1 : text2;
const string_t& shorttext = text1.length() > text2.length() ? text2 : text1;
const size_t i = longtext.find(shorttext);
if (i != string_t::npos) {
// Shorter text is inside the longer text (speedup).
const Operation op = (text1.length() > text2.length()) ? DELETE : INSERT;
diffs.push_back(Diff(op, longtext.substr(0, i)));
diffs.push_back(Diff(EQUAL, shorttext));
diffs.push_back(Diff(op, safeMid(longtext, i + shorttext.length())));
return;
}
if (shorttext.length() == 1) {
// Single character string.
// After the previous speedup, the character can't be an equality.
diffs.push_back(Diff(DELETE, text1));
diffs.push_back(Diff(INSERT, text2));
return;
}
// Garbage collect longtext and shorttext by scoping out.
}
// Don't risk returning a non-optimal diff if we have unlimited time.
if (deadline != std::numeric_limits<clock_t>::max()) {
// Check to see if the problem can be split in two.
HalfMatchResult hm;
if (diff_halfMatch(text1, text2, hm)) {
// A half-match was found, sort out the return data.
// Send both pairs off for separate processing.
diff_main(hm.text1_a, hm.text2_a, checklines, deadline, diffs);
diffs.push_back(Diff(EQUAL, hm.mid_common));
Diffs diffs_b;
diff_main(hm.text1_b, hm.text2_b, checklines, deadline, diffs_b);
diffs.splice(diffs.end(), diffs_b);
return;
}
}
// Perform a real diff.
if (checklines && text1.length() > 100 && text2.length() > 100) {
diff_lineMode(text1, text2, deadline, diffs);
return;
}
diff_bisect(text1, text2, deadline, diffs);
}
/**
* 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.
* @param diffs Linked List of Diff objects.
*/
private:
static void diff_lineMode(string_t text1, string_t text2, clock_t deadline, Diffs& diffs) {
// Scan the text on a line-by-line basis first.
Lines linearray;
diff_linesToChars(text1, text2, linearray);
diff_main(text1, text2, false, deadline, diffs);
// 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.push_back(Diff(EQUAL, string_t()));
int count_delete = 0;
int count_insert = 0;
string_t text_delete;
string_t text_insert;
for (typename Diffs::iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
switch ((*cur_diff).operation) {
case INSERT:
count_insert++;
text_insert += (*cur_diff).text;
break;
case DELETE:
count_delete++;
text_delete += (*cur_diff).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.
typename Diffs::iterator last = cur_diff;
std::advance(cur_diff, -(count_delete + count_insert));
cur_diff = diffs.erase(cur_diff, last);
Diffs new_diffs;
diff_main(text_delete, text_insert, false, deadline, new_diffs);
diffs.splice(cur_diff++, new_diffs);
--cur_diff;
}
count_insert = 0;
count_delete = 0;
text_delete.clear();
text_insert.clear();
break;
}
}
diffs.pop_back(); // Remove the dummy entry at the end.
}
/**
* 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:
static Diffs diff_bisect(const string_t &text1, const string_t &text2, clock_t deadline) {
Diffs diffs;
diff_bisect(text1, text2, deadline, diffs);
return diffs;
}
private:
static void diff_bisect(const string_t &text1, const string_t &text2, clock_t deadline, Diffs& diffs) {
// 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;
std::vector<int> v1(v_length, -1),
v2(v_length, -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.
diff_bisectSplit(text1, text2, x1, y1, deadline, diffs);
return;
}
}
}
}
// 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.
diff_bisectSplit(text1, text2, x1, y1, deadline, diffs);
return;
}
}
}
}
}
// Diff took too long and hit the deadline or
// number of diffs equals number of characters, no commonality at all.
diffs.clear();
diffs.push_back(Diff(DELETE, text1));
diffs.push_back(Diff(INSERT, text2));
}
/**
* 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.
* @param diffs LinkedList of Diff objects.
*/
private:
static void diff_bisectSplit(const string_t &text1, const string_t &text2, int x, int y, clock_t deadline, Diffs& diffs) {
string_t text1a = text1.substr(0, x);
string_t text2a = text2.substr(0, y);
string_t text1b = safeMid(text1, x);
string_t text2b = safeMid(text2, y);
// Compute both diffs serially.
diff_main(text1a, text2a, false, deadline, diffs);
Diffs diffs_b;
diff_main(text1b, text2b, false, deadline, diffs_b);
diffs.splice(diffs.end(), diffs_b);
}
protected:
struct LinePtr : std::pair<typename string_t::const_pointer, size_t> {
LinePtr() {}
LinePtr(typename string_t::const_pointer p, size_t n) : std::pair<typename string_t::const_pointer, size_t>(p, n) {}
bool operator<(const LinePtr& p) const
{ return this->second < p.second? true : this->second > p.second? false : string_t::traits_type::compare(this->first, p.first, this->second) < 0; }
};
struct Lines : std::vector<LinePtr> { string_t text1, text2; };
/**
* 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.
* @param lineArray Lines object, containing the encoded text1, the
* encoded text2 and the List of pointers to unique strings. The zeroth element
* of the List of unique strings is intentionally blank.
*/
static void diff_linesToChars(string_t &text1, string_t &text2, Lines& lineArray) {
std::map<LinePtr, size_t> lineHash;
lineArray.text1.swap(text1), lineArray.text2.swap(text2);
// 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.
text1 = diff_linesToCharsMunge(lineArray.text1, lineHash);
text2 = diff_linesToCharsMunge(lineArray.text2, lineHash);
lineArray.resize(lineHash.size() + 1);
for (typename std::map<LinePtr, size_t>::const_iterator i = lineHash.begin(); i != lineHash.end(); ++i)
lineArray[(*i).second] = (*i).first;
}
/**
* Split a text into a list of pointers to strings. Reduce the texts to a string of
* hashes where each Unicode character represents one line.
* @param text String to encode.
* @param lineHash Map of string pointers to indices.
* @return Encoded string.
*/
private:
static string_t diff_linesToCharsMunge(const string_t &text, std::map<LinePtr, size_t> &lineHash) {
string_t chars;
// Walk the text, pulling out a substring for each line.
// text.split('\n') would temporarily double our memory footprint.
// Modifying text would create many large strings to garbage collect.
typename string_t::size_type lineLen;
for (typename string_t::const_pointer lineStart = text.c_str(), textEnd = lineStart + text.size(); lineStart < textEnd; lineStart += lineLen + 1) {
lineLen = next_token(text, traits::from_wchar(L'\n'), lineStart);
if (lineStart + lineLen == textEnd) --lineLen;
chars += (char_t)(*lineHash.insert(std::make_pair(LinePtr(lineStart, lineLen + 1), lineHash.size() + 1)).first).second;
}
return chars;
}
/**
* 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 pointers to unique strings.
*/
private:
static void diff_charsToLines(Diffs &diffs, const Lines& lineArray) {
for (typename Diffs::iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
string_t text;
for (int y = 0; y < (int)(*cur_diff).text.length(); y++) {
const LinePtr& lp = lineArray[static_cast<size_t>((*cur_diff).text[y])];
text.append(lp.first, lp.second);
}
(*cur_diff).text.swap(text);
}
}
/**
* 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:
static int diff_commonPrefix(const string_t &text1, const string_t &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;
}
/**
* 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:
static int diff_commonSuffix(const string_t &text1, const string_t &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;
}
/**
* 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:
static int diff_commonOverlap(const string_t &text1, const string_t &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.
string_t text1_trunc = text1;
string_t text2_trunc = text2;
if (text1_length > text2_length) {
text1_trunc = right(text1, text2_length);
} else if (text1_length < text2_length) {
text2_trunc = text2.substr(0, 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) {
string_t pattern = right(text1_trunc, length);
size_t found = text2_trunc.find(pattern);
if (found == string_t::npos) {
return best;
}
length += found;
if (found == 0 || right(text1_trunc, length) == text2_trunc.substr(0, length)) {
best = length;
length++;
}
}
}
protected:
struct HalfMatchResult {
string_t text1_a, text1_b, text2_a, text2_b, mid_common;
void swap(HalfMatchResult& hm) {
text1_a.swap(hm.text1_a), text1_b.swap(hm.text1_b), text2_a.swap(hm.text2_a), text2_b.swap(hm.text2_b), mid_common.swap(hm.mid_common);
}
};
/**
* 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.
* @param hm HalfMatchResult object, containing the prefix of text1, the
* suffix of text1, the prefix of text2, the suffix of text2 and the
* common middle.
* @return Boolean true if there was a match, false otherwise.
*/
static bool diff_halfMatch(const string_t &text1, const string_t &text2, HalfMatchResult& hm) {
const string_t longtext = text1.length() > text2.length() ? text1 : text2;
const string_t shorttext = text1.length() > text2.length() ? text2 : text1;
if (longtext.length() < 4 || shorttext.length() * 2 < longtext.length()) {
return false; // Pointless.
}
HalfMatchResult res1, res2;
// First check if the second quarter is the seed for a half-match.
bool hm1 = diff_halfMatchI(longtext, shorttext,
(longtext.length() + 3) / 4, res1);
// Check again based on the third quarter.
bool hm2 = diff_halfMatchI(longtext, shorttext,
(longtext.length() + 1) / 2, res2);
if (!hm1 && !hm2) {
return false;
} else if (!hm2) {
hm.swap(res1);
} else if (!hm1) {
hm.swap(res2);
} else {
// Both matched. Select the longest.
hm.swap(res1.mid_common.length() > res2.mid_common.length() ? res1 : res2);
}
// A half-match was found, sort out the return data.
if (text1.length() <= text2.length()) {
hm.text1_a.swap(hm.text2_a);
hm.text1_b.swap(hm.text2_b);
}
return true;
}
/**
* 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.
* @param best HalfMatchResult object, containing the prefix of longtext, the
* suffix of longtext, the prefix of shorttext, the suffix of shorttext
* and the common middle.
* @return Boolean true if there was a match, false otherwise.
*/
private:
static bool diff_halfMatchI(const string_t &longtext, const string_t &shorttext, int i, HalfMatchResult& best) {
// Start with a 1/4 length substring at position i as a seed.
const string_t seed = safeMid(longtext, i, longtext.length() / 4);
size_t j = string_t::npos;
while ((j = shorttext.find(seed, j + 1)) != string_t::npos) {
const int prefixLength = diff_commonPrefix(safeMid(longtext, i),
safeMid(shorttext, j));
const int suffixLength = diff_commonSuffix(longtext.substr(0, i),
shorttext.substr(0, j));
if ((int)best.mid_common.length() < suffixLength + prefixLength) {
best.mid_common = safeMid(shorttext, j - suffixLength, suffixLength)
+ safeMid(shorttext, j, prefixLength);
best.text1_a = longtext.substr(0, i - suffixLength);
best.text1_b = safeMid(longtext, i + prefixLength);
best.text2_a = shorttext.substr(0, j - suffixLength);
best.text2_b = safeMid(shorttext, j + prefixLength);
}
}
return best.mid_common.length() * 2 >= longtext.length();
}
/**
* Reduce the number of edits by eliminating semantically trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public:
static void diff_cleanupSemantic(Diffs &diffs) {
if (diffs.empty()) {
return;
}
bool changes = false;
std::vector<typename Diffs::iterator> equalities; // Stack of equalities.
string_t lastequality; // Always equal to equalities.lastElement().text
typename Diffs::iterator cur_diff;
// 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;
for (cur_diff = diffs.begin(); cur_diff != diffs.end();) {
if ((*cur_diff).operation == EQUAL) {
// Equality found.
equalities.push_back(cur_diff);
length_insertions1 = length_insertions2;
length_deletions1 = length_deletions2;
length_insertions2 = 0;
length_deletions2 = 0;
lastequality = (*cur_diff).text;
} else {
// An insertion or deletion.
if ((*cur_diff).operation == INSERT) {
length_insertions2 += (*cur_diff).text.length();
} else {
length_deletions2 += (*cur_diff).text.length();
}
// Eliminate an equality that is smaller or equal to the edits on both
// sides of it.
if (!lastequality.empty()
&& ((int)lastequality.length()
<= std::max(length_insertions1, length_deletions1))
&& ((int)lastequality.length()
<= std::max(length_insertions2, length_deletions2))) {
// printf("Splitting: '%s'\n", qPrintable(lastequality));
// Walk back to offending equality.
// Change second copy to insert.
(*(cur_diff = equalities.back())).operation = INSERT;
// Duplicate record.
diffs.insert(cur_diff, Diff(DELETE, lastequality));
equalities.pop_back(); // Throw away the equality we just deleted.
if (!equalities.empty()) {
// Throw away the previous equality (it needs to be reevaluated).
equalities.pop_back();
}
length_insertions1 = 0; // Reset the counters.
length_deletions1 = 0;
length_insertions2 = 0;
length_deletions2 = 0;
lastequality = string_t();
changes = true;
if (!equalities.empty())
// There is a safe equality we can fall back to.
cur_diff = equalities.back();
else
{
// There are no previous equalities, walk back to the start.
cur_diff = diffs.begin();
continue;
}
}
}
++cur_diff;
}
// 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.
if ((cur_diff = diffs.begin()) != diffs.end()) {
for (typename Diffs::iterator prev_diff = cur_diff; ++cur_diff != diffs.end(); prev_diff = cur_diff) {
if ((*prev_diff).operation == DELETE &&
(*cur_diff).operation == INSERT) {
string_t deletion = (*prev_diff).text;
string_t insertion = (*cur_diff).text;
int overlap_length1 = diff_commonOverlap(deletion, insertion);
int overlap_length2 = diff_commonOverlap(insertion, deletion);
if (overlap_length1 >= overlap_length2) {
if (overlap_length1 >= deletion.size() / 2.0 ||
overlap_length1 >= insertion.size() / 2.0) {
// Overlap found. Insert an equality and trim the surrounding edits.
diffs.insert(cur_diff, Diff(EQUAL, insertion.substr(0, overlap_length1)));
prev_diff->text =
deletion.substr(0, deletion.length() - overlap_length1);
cur_diff->text = safeMid(insertion, overlap_length1);
// diffs.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.
diffs.insert(cur_diff, Diff(EQUAL, deletion.substr(0, overlap_length2)));
prev_diff->operation = INSERT;
prev_diff->text =
insertion.substr(0, insertion.length() - overlap_length2);
cur_diff->operation = DELETE;
cur_diff->text = safeMid(deletion, overlap_length2);
// diffs.insert inserts the element before the cursor, so there is
// no need to step past the new element.
}
}
if (++cur_diff == diffs.end()) break;
}
}
}
}
/**
* 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:
static void diff_cleanupSemanticLossless(Diffs &diffs) {
string_t equality1, edit, equality2;
string_t commonString;
int commonOffset;
int score, bestScore;
string_t bestEquality1, bestEdit, bestEquality2;
// Create a new iterator at the start.
typename Diffs::iterator prev_diff = diffs.begin(), cur_diff = prev_diff;
if (prev_diff == diffs.end() || ++cur_diff == diffs.end()) return;
// Intentionally ignore the first and last element (don't need checking).
for (typename Diffs::iterator next_diff = cur_diff; ++next_diff != diffs.end(); prev_diff = cur_diff, cur_diff = next_diff) {
if ((*prev_diff).operation == EQUAL &&
(*next_diff).operation == EQUAL) {
// This is a single edit surrounded by equalities.
equality1 = (*prev_diff).text;
edit = (*cur_diff).text;
equality2 = (*next_diff).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.substr(0, equality1.length() - commonOffset);
edit = commonString + edit.substr(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.empty() && !equality2.empty()
&& 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 ((*prev_diff).text != bestEquality1) {
// We have an improvement, save it back to the diff.
if (!bestEquality1.empty()) {
(*prev_diff).text = bestEquality1;
} else {
diffs.erase(prev_diff);
}
(*cur_diff).text = bestEdit;
if (!bestEquality2.empty()) {
(*next_diff).text = bestEquality2;
} else {
diffs.erase(next_diff); // Delete nextDiff.
next_diff = cur_diff;
cur_diff = prev_diff;
}
}
}
}
}
/**
* 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:
static int diff_cleanupSemanticScore(const string_t &one, const string_t &two) {
if (one.empty() || two.empty()) {
// Edges are the best.
return 6;
}
// Each port of this function behaves slightly differently due to
// subtle differences in each language's definition of things like
// 'whitespace'. Since this function's purpose is largely cosmetic,
// the choice has been made to use each language's native features
// rather than force total conformity.
char_t char1 = one[one.length() - 1];
char_t char2 = two[0];
bool nonAlphaNumeric1 = !traits::is_alnum(char1);
bool nonAlphaNumeric2 = !traits::is_alnum(char2);
bool whitespace1 = nonAlphaNumeric1 && traits::is_space(char1);
bool whitespace2 = nonAlphaNumeric2 && traits::is_space(char2);
bool lineBreak1 = whitespace1 && is_control(char1);
bool lineBreak2 = whitespace2 && is_control(char2);
bool blankLine1 = false;
if (lineBreak1) {
typename string_t::const_reverse_iterator p1 = one.rbegin(), p2 = one.rend();
if (traits::to_wchar(*p1) == L'\n' && ++p1 != p2) {
if (traits::to_wchar(*p1) == L'\r')
++p1;
blankLine1 = p1 != p2 && traits::to_wchar(*p1) == L'\n';
}
}
bool blankLine2 = false;
if (lineBreak2) {
typename string_t::const_iterator p1 = two.end(), p2 = two.begin();
if (traits::to_wchar(*p2) == L'\r')
++p2;
if (p2 != p1 && traits::to_wchar(*p2) == L'\n') {
if (++p2 != p1 && traits::to_wchar(*p2) == L'\r')
++p2;
if (p2 != p1 && traits::to_wchar(*p2) == L'\n')
blankLine2 = true;
}
}
if (blankLine1 || blankLine2) {
// Five points for blank lines.
return 5;
} else if (lineBreak1 || lineBreak2) {
// Four points for line breaks.
return 4;
} else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) {
// Three points for end of sentences.
return 3;
} else if (whitespace1 || whitespace2) {
// Two points for whitespace.
return 2;
} else if (nonAlphaNumeric1 || nonAlphaNumeric2) {
// One point for non-alphanumeric.
return 1;
}
return 0;
}
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param diffs LinkedList of Diff objects.
*/
public:
void diff_cleanupEfficiency(Diffs &diffs) const {
if (diffs.empty()) {
return;
}
bool changes = false;
std::vector<typename Diffs::iterator> equalities; // Stack of equalities.
string_t lastequality; // Always equal to equalities.lastElement().text
// 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;
for (typename Diffs::iterator cur_diff = diffs.begin(); cur_diff != diffs.end();) {
if ((*cur_diff).operation == EQUAL) {
// Equality found.
if ((int)(*cur_diff).text.length() < Diff_EditCost && (post_ins || post_del)) {
// Candidate found.
equalities.push_back(cur_diff);
pre_ins = post_ins;
pre_del = post_del;
lastequality = (*cur_diff).text;
} else {
// Not a candidate, and can never become one.
equalities.clear();
lastequality.clear();
}
post_ins = post_del = false;
} else {
// An insertion or deletion.
if ((*cur_diff).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.empty()
&& ((pre_ins && pre_del && post_ins && post_del)
|| (((int)lastequality.length() < Diff_EditCost / 2)
&& ((pre_ins ? 1 : 0) + (pre_del ? 1 : 0)
+ (post_ins ? 1 : 0) + (post_del ? 1 : 0)) == 3))) {
// printf("Splitting: '%s'\n", qPrintable(lastequality));
// Walk back to offending equality.
// Change second copy to insert.
(*(cur_diff = equalities.back())).operation = INSERT;
// Duplicate record.
diffs.insert(cur_diff, Diff(DELETE, lastequality));
equalities.pop_back(); // Throw away the equality we just deleted.
lastequality.clear();
changes = true;
if (pre_ins && pre_del) {
// No changes made which could affect previous entry, keep going.
post_ins = post_del = true;
equalities.clear();
} else {
if (!equalities.empty()) {
// Throw away the previous equality (it needs to be reevaluated).
equalities.pop_back();
}
post_ins = post_del = false;
if (!equalities.empty())
// There is a safe equality we can fall back to.
cur_diff = equalities.back();
else
{
// There are no previous equalities, walk back to the start.
cur_diff = diffs.begin();
continue;
}
}
}
}
++cur_diff;
}
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:
static void diff_cleanupMerge(Diffs &diffs) {
diffs.push_back(Diff(EQUAL, string_t())); // Add a dummy entry at the end.
typename Diffs::iterator prev_diff, cur_diff;
int count_delete = 0;
int count_insert = 0;
string_t text_delete;
string_t text_insert;
Diff *prevEqual = nullptr;
int commonlength;
for (cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
switch ((*cur_diff).operation) {
case INSERT:
count_insert++;
text_insert += (*cur_diff).text;
prevEqual = nullptr;
break;
case DELETE:
count_delete++;
text_delete += (*cur_diff).text;
prevEqual = nullptr;
break;
case EQUAL:
if (count_delete + count_insert > 1) {
// Delete the offending records.
prev_diff = cur_diff;
std::advance(prev_diff, -(count_delete + count_insert));
diffs.erase(prev_diff, cur_diff);
if (count_delete != 0 && count_insert != 0) {
// Factor out any common prefixes.
commonlength = diff_commonPrefix(text_insert, text_delete);
if (commonlength != 0) {
if (cur_diff != diffs.begin()) {
prev_diff = cur_diff;
if ((*--prev_diff).operation != EQUAL) {
llvm_unreachable("Previous diff should have been an equality.");
}
(*prev_diff).text += text_insert.substr(0, commonlength);
} else {
diffs.insert(cur_diff, Diff(EQUAL, text_insert.substr(0, commonlength)));
}
text_insert = safeMid(text_insert, commonlength);
text_delete = safeMid(text_delete, commonlength);
}
// Factor out any common suffixes.
commonlength = diff_commonSuffix(text_insert, text_delete);
if (commonlength != 0) {
(*cur_diff).text = safeMid(text_insert, text_insert.length()
- commonlength) + (*cur_diff).text;
text_insert = text_insert.substr(0, text_insert.length()
- commonlength);
text_delete = text_delete.substr(0, text_delete.length()
- commonlength);
}
}
// Insert the merged records.
if (!text_delete.empty()) {
diffs.insert(cur_diff, Diff(DELETE, text_delete));
}
if (!text_insert.empty()) {
diffs.insert(cur_diff, Diff(INSERT, text_insert));
}
} else if (prevEqual != nullptr) {
// Merge this equality with the previous one.
prevEqual->text += (*cur_diff).text;
diffs.erase(cur_diff--);
}
count_insert = 0;
count_delete = 0;
text_delete.clear();
text_insert.clear();
prevEqual = &*cur_diff;
break;
}
}
if (diffs.back().text.empty()) {
diffs.pop_back(); // Remove the dummy entry at the end.
}
/*
* Second pass: look for single edits surrounded on both sides by equalities
* which can be shifted sideways to eliminate an equality.
* e.g: A<ins>BA</ins>C -> <ins>AB</ins>AC
*/
bool changes = false;
// Create a new iterator at the start.
// (As opposed to walking the current one back.)
prev_diff = cur_diff = diffs.begin();
if (prev_diff != diffs.end() && ++cur_diff != diffs.end()) {
// Intentionally ignore the first and last element (don't need checking).
for (typename Diffs::iterator next_diff = cur_diff; ++next_diff != diffs.end(); prev_diff = cur_diff, cur_diff = next_diff) {
if ((*prev_diff).operation == EQUAL &&
(*next_diff).operation == EQUAL) {
// This is a single edit surrounded by equalities.
if ((*cur_diff).text.size() >= (*prev_diff).text.size() &&
(*cur_diff).text.compare((*cur_diff).text.size() - (*prev_diff).text.size(), (*prev_diff).text.size(), (*prev_diff).text) == 0) {
// Shift the edit over the previous equality.
(*cur_diff).text = (*prev_diff).text
+ (*cur_diff).text.substr(0, (*cur_diff).text.length()
- (*prev_diff).text.length());
(*next_diff).text = (*prev_diff).text + (*next_diff).text;
diffs.erase(prev_diff);
cur_diff = next_diff;
changes = true;
if (++next_diff == diffs.end()) break;
} else if ((*cur_diff).text.size() >= (*next_diff).text.size() && (*cur_diff).text.compare(0, (*next_diff).text.size(), (*next_diff).text) == 0) {
// Shift the edit over the next equality.
(*prev_diff).text += (*next_diff).text;
(*cur_diff).text = safeMid((*cur_diff).text, (*next_diff).text.length())
+ (*next_diff).text;
next_diff = diffs.erase(next_diff); // Delete nextDiff.
changes = true;
if (next_diff == diffs.end()) break;
}
}
}
}
// 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:
static int diff_xIndex(const Diffs &diffs, int loc) {
int chars1 = 0;
int chars2 = 0;
int last_chars1 = 0;
int last_chars2 = 0;
typename Diffs::const_iterator last_diff = diffs.end(), cur_diff;
for (cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
if ((*cur_diff).operation != INSERT) {
// Equality or deletion.
chars1 += (*cur_diff).text.length();
}
if ((*cur_diff).operation != DELETE) {
// Equality or insertion.
chars2 += (*cur_diff).text.length();
}
if (chars1 > loc) {
// Overshot the location.
last_diff = cur_diff;
break;
}
last_chars1 = chars1;
last_chars2 = chars2;
}
if (last_diff != diffs.end() && (*last_diff).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:
static string_t diff_prettyHtml(const Diffs &diffs) {
string_t html;
string_t text;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
typename string_t::size_type n = (*cur_diff).text.size();
typename string_t::const_pointer p, end;
for (p = (*cur_diff).text.c_str(), end = p + n; p != end; ++p)
switch (traits::to_wchar(*p)) {
case L'&': n += 4; break;
case L'<':
case L'>': n += 3; break;
case L'\n': n += 9; break;
}
if (n == (*cur_diff).text.size())
text = (*cur_diff).text;
else {
text.clear();
text.reserve(n);
for (p = (*cur_diff).text.c_str(); p != end; ++p)
switch (traits::to_wchar(*p)) {
case L'&': text += traits::cs(L"&"); break;
case L'<': text += traits::cs(L"<"); break;
case L'>': text += traits::cs(L">"); break;
case L'\n': text += traits::cs(L"¶<br>"); break;
default: text += *p;
}
}
switch ((*cur_diff).operation) {
case INSERT:
html += traits::cs(L"<ins style=\"background:#e6ffe6;\">") + text + traits::cs(L"</ins>");
break;
case DELETE:
html += traits::cs(L"<del style=\"background:#ffe6e6;\">") + text + traits::cs(L"</del>");
break;
case EQUAL:
html += traits::cs(L"<span>") + text + traits::cs(L"</span>");
break;
}
}
return html;
}
/**
* Compute and return the source text (all equalities and deletions).
* @param diffs LinkedList of Diff objects.
* @return Source text.
*/
public:
static string_t diff_text1(const Diffs &diffs) {
string_t text;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
if ((*cur_diff).operation != INSERT) {
text += (*cur_diff).text;
}
}
return text;
}
/**
* Compute and return the destination text (all equalities and insertions).
* @param diffs LinkedList of Diff objects.
* @return Destination text.
*/
public:
static string_t diff_text2(const Diffs &diffs) {
string_t text;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
if ((*cur_diff).operation != DELETE) {
text += (*cur_diff).text;
}
}
return text;
}
/**
* Compute the Levenshtein distance; the number of inserted, deleted or
* substituted characters.
* @param diffs LinkedList of Diff objects.
* @return Number of changes.
*/
public:
static int diff_levenshtein(const Diffs &diffs) {
int levenshtein = 0;
int insertions = 0;
int deletions = 0;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
switch ((*cur_diff).operation) {
case INSERT:
insertions += (*cur_diff).text.length();
break;
case DELETE:
deletions += (*cur_diff).text.length();
break;
case EQUAL:
// A deletion and an insertion is one substitution.
levenshtein += std::max(insertions, deletions);
insertions = 0;
deletions = 0;
break;
}
}
levenshtein += std::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:
static string_t diff_toDelta(const Diffs &diffs) {
string_t text;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
switch ((*cur_diff).operation) {
case INSERT: {
text += traits::from_wchar(L'+');
append_percent_encoded(text, (*cur_diff).text);
text += traits::from_wchar(L'\t');
break;
}
case DELETE:
text += traits::from_wchar(L'-') + to_string((*cur_diff).text.length()) + traits::from_wchar(L'\t');
break;
case EQUAL:
text += traits::from_wchar(L'=') + to_string((*cur_diff).text.length()) + traits::from_wchar(L'\t');
break;
}
}
if (!text.empty()) {
// Strip off trailing tab character.
text = text.substr(0, text.length() - 1);
}
return text;
}
/**
* 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 string_t If invalid input.
*/
public:
static Diffs diff_fromDelta(const string_t &text1, const string_t &delta) {
Diffs diffs;
int pointer = 0; // Cursor in text1
typename string_t::size_type token_len;
for (typename string_t::const_pointer token = delta.c_str(); token - delta.c_str() < (int)delta.length(); token += token_len + 1) {
token_len = next_token(delta, traits::from_wchar(L'\t'), token);
if (token_len == 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_t param(token + 1, token_len - 1);
switch (traits::to_wchar(*token)) {
case L'+':
percent_decode(param);
diffs.push_back(Diff(INSERT, param));
break;
case L'-':
// Fall through.
case L'=': {
int n;
n = to_int(param);
if (n < 0) {
llvm_unreachable("Negative number in diff_fromDelta: " + param);
}
string_t text;
text = safeMid(text1, pointer, n);
pointer += n;
if (traits::to_wchar(*token) == L'=') {
diffs.push_back(Diff(EQUAL, text));
} else {
diffs.push_back(Diff(DELETE, text));
}
break;
}
default:
llvm_unreachable(traits::cs(L"Invalid diff operation in diff_fromDelta: " + *token));
}
}
if (pointer != text1.length()) {
llvm_unreachable(traits::cs(L"Delta length (") + to_string(pointer)
+ traits::cs(L") smaller than source text length (")
+ to_string(text1.length()) + traits::from_wchar(L')'));
}
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(const string_t &text, const string_t &pattern, int loc) const {
loc = std::max(0, std::min(loc, (int)text.length()));
if (text == pattern) {
// Shortcut (potentially not guaranteed by the algorithm)
return 0;
} else if (text.empty()) {
// Nothing to match.
return -1;
} else if (loc + pattern.length() <= text.length()
&& safeMid(text, loc, pattern.length()) == pattern) {
// Perfect match at the perfect spot! (Includes case of null pattern)
return loc;
} else {
// Do a fuzzy compare.
return match_bitap(text, pattern, loc);
}
}
/**
* Locate the best instance of 'pattern' in 'text' near 'loc' using the
* Bitap algorithm. Returns -1 if no match found.
* @param text The text to search.
* @param pattern The pattern to search for.
* @param loc The location to search around.
* @return Best match index or -1.
*/
protected:
int match_bitap(const string_t &text, const string_t &pattern, int loc) const {
if (!(Match_MaxBits == 0 || (int)pattern.length() <= Match_MaxBits)) {
llvm_unreachable("Pattern too long for this application.");
}
// Initialise the alphabet.
std::map<char_t, int> s;
match_alphabet(pattern, s);
// Highest score beyond which we give up.
double score_threshold = Match_Threshold;
// Is there a nearby exact match? (speedup)
size_t best_loc = text.find(pattern, loc);
if (best_loc != string_t::npos) {
score_threshold = std::min(match_bitapScore(0, best_loc, loc, pattern),
score_threshold);
// What about in the other direction? (speedup)
best_loc = text.rfind(pattern, loc + pattern.length());
if (best_loc != string_t::npos) {
score_threshold = std::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();
int *rd;
int *last_rd = nullptr;
for (int d = 0; d < (int)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 = std::max(1, loc - bin_mid + 1);
int finish = std::min(loc + bin_mid, (int)text.length()) + pattern.length();
rd = new int[finish + 2];
rd[finish + 1] = (1 << d) - 1;
for (int j = finish; j >= start; j--) {
int charMatch;
if ((int)text.length() <= j - 1) {
// Out of range.
charMatch = 0;
} else {
charMatch = s[text[j - 1]];
}
if (d == 0) {
// First pass: exact match.
rd[j] = ((rd[j + 1] << 1) | 1) & charMatch;
} else {
// Subsequent passes: fuzzy match.
rd[j] = (((rd[j + 1] << 1) | 1) & charMatch)
| (((last_rd[j + 1] | last_rd[j]) << 1) | 1)
| last_rd[j + 1];
}
if ((rd[j] & matchmask) != 0) {
double score = match_bitapScore(d, j - 1, loc, pattern);
// This match will almost certainly be better than any existing
// match. But check anyway.
if (score <= score_threshold) {
// Told you so.
score_threshold = score;
best_loc = j - 1;
if (best_loc > loc) {
// When passing loc, don't exceed our current distance from loc.
start = std::max(1, 2 * loc - (int)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;
}
delete [] last_rd;
last_rd = rd;
}
delete [] last_rd;
delete [] 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, const string_t &pattern) const {
const float accuracy = static_cast<float> (e) / pattern.length();
const int proximity = (loc - x < 0)? (x - loc) : (loc - x);
if (Match_Distance == 0) {
// Dodge divide by zero error.
return proximity == 0 ? accuracy : 1.0;
}
return accuracy + (proximity / static_cast<float> (Match_Distance));
}
/**
* Initialise the alphabet for the Bitap algorithm.
* @param pattern The text to encode.
* @param s Hash of character locations.
*/
protected:
static void match_alphabet(const string_t &pattern, std::map<char_t, int>& s) {
// There is no need to initialize map values, since they are zero-initialized by default
for (size_t i = 0; i < pattern.length(); i++)
s[pattern[i]] |= (1 << (pattern.length() - i - 1));
}
// 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 string_t &text) const {
if (text.empty()) {
return;
}
string_t pattern = safeMid(text, 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.find(pattern) != text.rfind(pattern)
&& (int)pattern.length() < Match_MaxBits - Patch_Margin - Patch_Margin) {
padding += Patch_Margin;
pattern = safeMid(text, std::max(0, patch.start2 - padding),
std::min((int)text.length(), patch.start2 + patch.length1 + padding)
- std::max(0, patch.start2 - padding));
}
// Add one chunk for good luck.
padding += Patch_Margin;
// Add the prefix.
string_t prefix = safeMid(text, std::max(0, patch.start2 - padding),
patch.start2 - std::max(0, patch.start2 - padding));
if (!prefix.empty()) {
patch.diffs.push_front(Diff(EQUAL, prefix));
}
// Add the suffix.
string_t suffix = safeMid(text, patch.start2 + patch.length1,
std::min((int)text.length(), patch.start2 + patch.length1 + padding)
- (patch.start2 + patch.length1));
if (!suffix.empty()) {
patch.diffs.push_back(Diff(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:
Patches patch_make(const string_t &text1, const string_t &text2) const {
// No diffs provided, compute our own.
Diffs 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:
Patches patch_make(const Diffs &diffs) const {
// No origin string provided, compute our own.
return patch_make(diff_text1(diffs), 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.
* @note Prefer patch_make(const string_t &text1, const Diffs &diffs).
*/
public:
Patches patch_make(const string_t &text1, const string_t &text2, const Diffs &diffs) const {
return patch_make(text1, diffs); // text2 is entirely unused.
}
/**
* 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:
Patches patch_make(const string_t &text1, const Diffs &diffs) const {
Patches patches;
if (!diffs.empty()) { // Get rid of the null case.
Patch 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_t prepatch_text = text1;
string_t postpatch_text = text1;
for (typename Diffs::const_iterator cur_diff = diffs.begin(); cur_diff != diffs.end(); ++cur_diff) {
if (patch.diffs.empty() && (*cur_diff).operation != EQUAL) {
// A new patch starts here.
patch.start1 = char_count1;
patch.start2 = char_count2;
}
switch ((*cur_diff).operation) {
case INSERT:
patch.diffs.push_back(*cur_diff);
patch.length2 += (*cur_diff).text.length();
postpatch_text = postpatch_text.substr(0, char_count2)
+ (*cur_diff).text + safeMid(postpatch_text, char_count2);
break;
case DELETE:
patch.length1 += (*cur_diff).text.length();
patch.diffs.push_back(*cur_diff);
postpatch_text = postpatch_text.substr(0, char_count2)
+ safeMid(postpatch_text, char_count2 + (*cur_diff).text.length());
break;
case EQUAL:
if ((int)(*cur_diff).text.length() <= 2 * Patch_Margin
&& !patch.diffs.empty() && !(*cur_diff == diffs.back())) {
// Small equality inside a patch.
patch.diffs.push_back(*cur_diff);
patch.length1 += (*cur_diff).text.length();
patch.length2 += (*cur_diff).text.length();
}
if ((int)(*cur_diff).text.length() >= 2 * Patch_Margin) {
// Time for a new patch.
if (!patch.diffs.empty()) {
patch_addContext(patch, prepatch_text);
patches.push_back(patch);
patch = 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 ((*cur_diff).operation != INSERT) {
char_count1 += (*cur_diff).text.length();
}
if ((*cur_diff).operation != DELETE) {
char_count2 += (*cur_diff).text.length();
}
}
// Pick up the leftover patch if not empty.
if (!patch.diffs.empty()) {
patch_addContext(patch, prepatch_text);
patches.push_back(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:
Patches patch_deepCopy(const Patches &patches) const { return 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:
std::pair<string_t, std::vector<bool> > patch_apply(const Patches &patches, const string_t &text) const
{ std::pair<string_t, std::vector<bool> > res; patch_apply(patches, text, res); return res; }
void patch_apply(const Patches &patches, const string_t &sourceText, std::pair<string_t, std::vector<bool> >& res) const {
if (patches.empty()) {
res.first = sourceText;
res.second.clear();
return;
}
string_t text = sourceText; // Copy to preserve original.
// Deep copy the patches so that no changes are made to originals.
// Patches patchesCopy = patch_deepCopy(patches);
Patches patchesCopy(patches); // Default copy constructor will do it just fine
string_t nullPadding = patch_addPadding(patchesCopy);
text = nullPadding + text + nullPadding;
patch_splitMax(patchesCopy);
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;
std::vector<bool>& results = res.second;
results.resize(patchesCopy.size());
string_t text1, text2;
for (typename Patches::const_iterator cur_patch = patchesCopy.begin(); cur_patch != patchesCopy.end(); ++cur_patch) {
int expected_loc = (*cur_patch).start2 + delta;
text1 = diff_text1((*cur_patch).diffs);
int start_loc;
int end_loc = -1;
if ((int)text1.length() > Match_MaxBits) {
// patch_splitMax will only provide an oversized pattern in the case of
// a monster delete.
start_loc = match_main(text, text1.substr(0, Match_MaxBits), expected_loc);
if (start_loc != -1) {
end_loc = match_main(text, right(text1, Match_MaxBits),
expected_loc + text1.length() - 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 -= (*cur_patch).length2 - (*cur_patch).length1;
} else {
// Found a match. :)
results[x] = true;
delta = start_loc - expected_loc;
if (end_loc == -1) {
text2 = safeMid(text, start_loc, text1.length());
} else {
text2 = safeMid(text, start_loc, end_loc + Match_MaxBits - start_loc);
}
if (text1 == text2) {
// Perfect match, just shove the replacement text in.
text = text.substr(0, start_loc) + diff_text2((*cur_patch).diffs) + safeMid(text, start_loc + text1.length());
} else {
// Imperfect match. Run a diff to get a framework of equivalent
// indices.
Diffs diffs = diff_main(text1, text2, false);
if ((int)text1.length() > Match_MaxBits
&& diff_levenshtein(diffs) / static_cast<float> (text1.length())
> Patch_DeleteThreshold) {
// The end points match, but the content is unacceptably bad.
results[x] = false;
} else {
diff_cleanupSemanticLossless(diffs);
int index1 = 0;
for (typename Diffs::const_iterator cur_diff = (*cur_patch).diffs.begin(); cur_diff != (*cur_patch).diffs.end(); ++cur_diff) {
if ((*cur_diff).operation != EQUAL) {
int index2 = diff_xIndex(diffs, index1);
if ((*cur_diff).operation == INSERT) {
// Insertion
text = text.substr(0, start_loc + index2) + (*cur_diff).text
+ safeMid(text, start_loc + index2);
} else if ((*cur_diff).operation == DELETE) {
// Deletion
text = text.substr(0, start_loc + index2)
+ safeMid(text, start_loc + diff_xIndex(diffs,
index1 + (*cur_diff).text.length()));
}
}
if ((*cur_diff).operation != DELETE) {
index1 += (*cur_diff).text.length();
}
}
}
}
}
x++;
}
// Strip the padding off.
res.first = safeMid(text, nullPadding.length(), text.length() - 2 * nullPadding.length());
}
/**
* 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_t patch_addPadding(Patches &patches) const {
short paddingLength = Patch_Margin;
string_t nullPadding;
for (short x = 1; x <= paddingLength; x++) {
nullPadding += (char_t)x;
}
// Bump all the patches forward.
for (typename Patches::iterator cur_patch = patches.begin(); cur_patch != patches.end(); ++cur_patch) {
(*cur_patch).start1 += paddingLength;
(*cur_patch).start2 += paddingLength;
}
// Add some padding on start of first diff.
Patch &firstPatch = patches.front();
Diffs &firstPatchDiffs = firstPatch.diffs;
if (firstPatchDiffs.empty() || firstPatchDiffs.front().operation != EQUAL) {
// Add nullPadding equality.
firstPatchDiffs.push_front(Diff(EQUAL, nullPadding));
firstPatch.start1 -= paddingLength; // Should be 0.
firstPatch.start2 -= paddingLength; // Should be 0.
firstPatch.length1 += paddingLength;
firstPatch.length2 += paddingLength;
} else if (paddingLength > (int)firstPatchDiffs.front().text.length()) {
// Grow first equality.
Diff &firstDiff = firstPatchDiffs.front();
int extraLength = paddingLength - firstDiff.text.length();
firstDiff.text = safeMid(nullPadding, firstDiff.text.length(),
paddingLength - firstDiff.text.length()) + firstDiff.text;
firstPatch.start1 -= extraLength;
firstPatch.start2 -= extraLength;
firstPatch.length1 += extraLength;
firstPatch.length2 += extraLength;
}
// Add some padding on end of last diff.
Patch &lastPatch = patches.front();
Diffs &lastPatchDiffs = lastPatch.diffs;
if (lastPatchDiffs.empty() || lastPatchDiffs.back().operation != EQUAL) {
// Add nullPadding equality.
lastPatchDiffs.push_back(Diff(EQUAL, nullPadding));
lastPatch.length1 += paddingLength;
lastPatch.length2 += paddingLength;
} else if (paddingLength > (int)lastPatchDiffs.back().text.length()) {
// Grow last equality.
Diff &lastDiff = lastPatchDiffs.back();
int extraLength = paddingLength - lastDiff.text.length();
lastDiff.text += nullPadding.substr(0, extraLength);
lastPatch.length1 += extraLength;
lastPatch.length2 += extraLength;
}
return nullPadding;
}
/**
* Look through the patches and break up any which are longer than the
* maximum limit of the match algorithm.
* Intended to be called only from within patch_apply.
* @param patches LinkedList of Patch objects.
*/
public:
void patch_splitMax(Patches &patches) const {
short patch_size = Match_MaxBits;
string_t precontext, postcontext;
Patch patch;
int start1, start2;
bool empty;
Operation diff_type;
string_t diff_text;
Patch bigpatch;
for (typename Patches::iterator cur_patch = patches.begin(); cur_patch != patches.end();) {
if ((*cur_patch).length1 <= patch_size) { ++cur_patch; continue; }
bigpatch = *cur_patch;
// Remove the big old patch.
cur_patch = patches.erase(cur_patch);
start1 = bigpatch.start1;
start2 = bigpatch.start2;
precontext.clear();
while (!bigpatch.diffs.empty()) {
// Create one of several smaller patches.
patch = Patch();
empty = true;
patch.start1 = start1 - precontext.length();
patch.start2 = start2 - precontext.length();
if (!precontext.empty()) {
patch.length1 = patch.length2 = precontext.length();
patch.diffs.push_back(Diff(EQUAL, precontext));
}
while (!bigpatch.diffs.empty()
&& patch.length1 < patch_size - Patch_Margin) {
diff_type = bigpatch.diffs.front().operation;
diff_text = bigpatch.diffs.front().text;
if (diff_type == INSERT) {
// Insertions are harmless.
patch.length2 += diff_text.length();
start2 += diff_text.length();
patch.diffs.push_back(bigpatch.diffs.front());
bigpatch.diffs.pop_front();
empty = false;
} else if (diff_type == DELETE && patch.diffs.size() == 1
&& patch.diffs.front().operation == EQUAL
&& (int)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.push_back(Diff(diff_type, diff_text));
bigpatch.diffs.pop_front();
} else {
// Deletion or equality. Only take as much as we can stomach.
diff_text = diff_text.substr(0, std::min((int)diff_text.length(),
patch_size - patch.length1 - Patch_Margin));
patch.length1 += diff_text.length();
start1 += diff_text.length();
if (diff_type == EQUAL) {
patch.length2 += diff_text.length();
start2 += diff_text.length();
} else {
empty = false;
}
patch.diffs.push_back(Diff(diff_type, diff_text));
if (diff_text == bigpatch.diffs.front().text) {
bigpatch.diffs.pop_front();
} else {
bigpatch.diffs.front().text = safeMid(bigpatch.diffs.front().text, diff_text.length());
}
}
}
// Compute the head context for the next patch.
precontext = safeMid(diff_text2(patch.diffs), std::max(0, (int)precontext.length() - Patch_Margin));
// Append the end context for this patch.
postcontext = diff_text1(bigpatch.diffs);
if ((int)postcontext.length() > Patch_Margin) {
postcontext = postcontext.substr(0, Patch_Margin);
}
if (!postcontext.empty()) {
patch.length1 += postcontext.length();
patch.length2 += postcontext.length();
if (!patch.diffs.empty()
&& patch.diffs.back().operation == EQUAL) {
patch.diffs.back().text += postcontext;
} else {
patch.diffs.push_back(Diff(EQUAL, postcontext));
}
}
if (!empty) {
patches.insert(cur_patch, patch);
}
}
}
}
/**
* Take a list of patches and return a textual representation.
* @param patches List of Patch objects.
* @return Text representation of patches.
*/
public:
static string_t patch_toText(const Patches &patches) {
string_t text;
for (typename Patches::const_iterator cur_patch = patches.begin(); cur_patch != patches.end(); ++cur_patch) {
text += (*cur_patch).toString();
}
return text;
}
/**
* 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 string_t If invalid input.
*/
public:
Patches patch_fromText(const string_t &textline) const {
Patches patches;
if (!textline.empty()) {
char_t sign;
string_t line;
typename string_t::const_pointer text = textline.c_str();
typename string_t::size_type text_len, l;
while (text - textline.c_str() < (int)textline.length()) {
if ((text_len = next_token(textline, traits::from_wchar(L'\n'), text)) == 0) { ++text; continue; }
// A replacement for the regexp "^@@ -(\\d+),?(\\d*) \\+(\\d+),?(\\d*) @@$" exact match
string_t start1, length1, start2, length2;
do {
typename string_t::const_pointer t = text;
l = text_len;
if ((l -= 9) > 0 && traits::to_wchar(*t) == L'@' && traits::to_wchar(*++t) == L'@'
&& traits::to_wchar(*++t) == L' ' && traits::to_wchar(*++t) == L'-' && traits::is_digit(*++t)) {
do { start1 += *t; } while (--l > 0 && traits::is_digit(*++t));
if (l > 0 && traits::to_wchar(*t) == L',') ++t, --l;
while (l > 0 && traits::is_digit(*t)) --l, length1 += *t++;
if (l > 0 && traits::to_wchar(*t++) == L' ' && traits::to_wchar(*t++) == L'+' && traits::is_digit(*t)) {
do { start2 += *t; --l; } while (traits::is_digit(*++t));
if (l > 0 && traits::to_wchar(*t) == L',') ++t, --l;
while (l > 0 && traits::is_digit(*t)) --l, length2 += *t++;
if (l == 0 && traits::to_wchar(*t++) == L' ' && traits::to_wchar(*t++) == L'@' && traits::to_wchar(*t) == L'@') break; // Success
}
}
llvm_unreachable(traits::cs(L"Invalid patch string: ") + string_t(text, text_len));
} while (false);
Patch patch;
patch.start1 = to_int(start1);
if (length1.empty()) {
patch.start1--;
patch.length1 = 1;
} else if (length1.size() == 1 && traits::to_wchar(length1[0]) == L'0') {
patch.length1 = 0;
} else {
patch.start1--;
patch.length1 = to_int(length1);
}
patch.start2 = to_int(start2);
if (length2.empty()) {
patch.start2--;
patch.length2 = 1;
} else if (length2.size() == 1 && traits::to_wchar(length2[0]) == L'0') {
patch.length2 = 0;
} else {
patch.start2--;
patch.length2 = to_int(length2);
}
for (text += text_len + 1; text - textline.c_str() < (int)textline.length(); text += text_len + 1) {
if ((text_len = next_token(textline, traits::from_wchar(L'\n'), text)) == 0) continue;
sign = *text;
line.assign(text + 1, text_len - 1);
percent_decode(line);
switch (traits::to_wchar(sign)) {
case L'-':
// Deletion.
patch.diffs.push_back(Diff(DELETE, line));
continue;
case L'+':
// Insertion.
patch.diffs.push_back(Diff(INSERT, line));
continue;
case L' ':
// Minor equality.
patch.diffs.push_back(Diff(EQUAL, line));
continue;
case L'@':
// Start of next patch.
break;
default:
// WTF?
llvm_unreachable(traits::cs(L"Invalid patch mode '") + (sign + (traits::cs(L"' in: ") + line)));
}
break;
}
patches.push_back(patch);
}
}
return patches;
}
/**
* A safer version of string_t.mid(pos). This one returns "" instead of
* null when the position 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 string_t safeMid(const string_t &str, size_t pos) {
return (pos == str.length()) ? string_t() : str.substr(pos);
}
/**
* A safer version of string_t.mid(pos, len). This one returns "" instead of
* null when the position 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 string_t safeMid(const string_t &str, size_t pos, size_t len) {
return (pos == str.length()) ? string_t() : str.substr(pos, len);
}
/**
* Utility functions
*/
private:
static string_t to_string(int n) {
string_t str;
bool negative = false;
size_t l = 0;
if (n < 0) n = -n, ++l, negative = true;
int n_ = n; do { ++l; } while ((n_ /= 10) > 0);
str.resize(l);
typename string_t::iterator s = str.end();
const wchar_t digits[] = L"0123456789";
do { *--s = traits::from_wchar(digits[n % 10]); } while ((n /= 10) > 0);
if (negative) *--s = traits::from_wchar(L'-');
return str;
}
static int to_int(const string_t& str) { return traits::to_int(str.c_str()); }
static bool is_control(char_t c) { switch (traits::to_wchar(c)) { case L'\n': case L'\r': return true; } return false; }
static typename string_t::size_type next_token(const string_t& str, char_t delim, typename string_t::const_pointer off) {
typename string_t::const_pointer p = off, end = str.c_str() + str.length();
for (; p != end; ++p) if (*p == delim) break;
return p - off;
}
static void append_percent_encoded(string_t& s1, const string_t& s2) {
const wchar_t safe_chars[] = L"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_.~ !*'();/?:@&=+$,#";
size_t safe[0x100], i;
for (i = 0; i < 0x100; ++i) safe[i] = 0;
for (i = 0; i < sizeof(safe_chars) / sizeof(wchar_t); ++i) safe[safe_chars[i]] = i + 1;
int n = 0;
typename traits::utf32_t u;
typename string_t::const_pointer c = s2.c_str(), end = c + s2.length();
while (c != end) {
c = traits::to_utf32(c, end, u);
n += u >= 0x10000? 12 : u >= 0x800? 9 : u >= 0x80? 6 : safe[static_cast<unsigned char>(u)]? 1 : 3;
}
if (n == int(s2.length()))
s1.append(s2);
else {
s1.reserve(s1.size() + n);
// Encode as UTF-8, then escape unsafe characters
unsigned char utf8[4];
for (c = s2.c_str(); c != end;) {
c = traits::to_utf32(c, end, u);
unsigned char* pt = utf8;
if (u < 0x80)
*pt++ = (unsigned char)u;
else if (u < 0x800) {
*pt++ = (unsigned char)((u >> 6) | 0xC0);
*pt++ = (unsigned char)((u & 0x3F) | 0x80);
}
else if (u < 0x10000) {
*pt++ = (unsigned char)((u >> 12) | 0xE0);
*pt++ = (unsigned char)(((u >> 6) & 0x3F) | 0x80);
*pt++ = (unsigned char)((u & 0x3F) | 0x80);
}
else {
*pt++ = (unsigned char)((u >> 18) | 0xF0);
*pt++ = (unsigned char)(((u >> 12) & 0x3F) | 0x80);
*pt++ = (unsigned char)(((u >> 6) & 0x3F) | 0x80);
*pt++ = (unsigned char)((u & 0x3F) | 0x80);
}
for (const unsigned char* p = utf8; p < pt; ++p)
if (safe[*p])
s1 += traits::from_wchar(safe_chars[safe[*p] - 1]);
else {
s1 += traits::from_wchar(L'%');
s1 += traits::from_wchar(safe_chars[(*p & 0xF0) >> 4]);
s1 += traits::from_wchar(safe_chars[*p & 0xF]);
}
}
}
}
static unsigned hex_digit_value(char_t c) {
switch (traits::to_wchar(c))
{
case L'0': return 0;
case L'1': return 1;
case L'2': return 2;
case L'3': return 3;
case L'4': return 4;
case L'5': return 5;
case L'6': return 6;
case L'7': return 7;
case L'8': return 8;
case L'9': return 9;
case L'A': case L'a': return 0xA;
case L'B': case L'b': return 0xB;
case L'C': case L'c': return 0xC;
case L'D': case L'd': return 0xD;
case L'E': case L'e': return 0xE;
case L'F': case L'f': return 0xF;
}
llvm_unreachable(string_t(traits::cs(L"Invalid character: ")) + c);
}
static void percent_decode(string_t& str) {
typename string_t::iterator s2 = str.begin(), s3 = s2, s4 = s2;
for (typename string_t::const_pointer s1 = str.c_str(), end = s1 + str.size(); s1 != end; ++s1, ++s2)
if (traits::to_wchar(*s1) != L'%')
*s2 = *s1;
else {
char_t d1 = *++s1;
*s2 = char_t((hex_digit_value(d1) << 4) + hex_digit_value(*++s1));
}
// Decode UTF-8 string in-place
while (s3 != s2) {
unsigned u = *s3;
if (u < 0x80)
;
else if ((u >> 5) == 6) {
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u = ((u & 0x1F) << 6) + (*s3 & 0x3F);
}
else if ((u >> 4) == 0xE) {
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u = ((u & 0xF) << 12) + ((*s3 & 0x3F) << 6);
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u += *s3 & 0x3F;
}
else if ((u >> 3) == 0x1E) {
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u = ((u & 7) << 18) + ((*s3 & 0x3F) << 12);
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u += (*s3 & 0x3F) << 6;
if (++s3 == s2 || (*s3 & 0xC0) != 0x80) continue;
u += *s3 & 0x3F;
}
else {
++s3;
continue;
}
s4 = traits::from_utf32(u, s4);
++s3;
}
if (s4 != str.end()) str.resize(s4 - str.begin());
}
static string_t right(const string_t& str, typename string_t::size_type n) { return str.substr(str.size() - n); }
};
/**
* Functions dependent on character type
*/
// Unicode helpers
template <class char_t, class utf32_type = unsigned>
struct diff_match_patch_utf32_direct {
typedef utf32_type utf32_t;
template <class iterator> static iterator to_utf32(iterator i, iterator /*end*/, utf32_t& u)
{
u = *i++;
return i;
}
template <class iterator> static iterator from_utf32(utf32_t u, iterator o)
{
*o++ = static_cast<char_t>(u);
return o;
}
};
template <class char_t, class utf32_type = unsigned>
struct diff_match_patch_utf32_from_utf16 {
typedef utf32_type utf32_t;
static const unsigned UTF16_SURROGATE_MIN = 0xD800u;
static const unsigned UTF16_SURROGATE_MAX = 0xDFFFu;
static const unsigned UTF16_HIGH_SURROGATE_MAX = 0xDBFFu;
static const unsigned UTF16_LOW_SURROGATE_MIN = 0xDC00u;
static const unsigned UTF16_SURROGATE_OFFSET = (UTF16_SURROGATE_MIN << 10) + UTF16_HIGH_SURROGATE_MAX - 0xFFFFu;
template <class iterator> static iterator to_utf32(iterator i, iterator end, utf32_t& u)
{
u = *i++;
if (UTF16_SURROGATE_MIN <= u && u <= UTF16_HIGH_SURROGATE_MAX && i != end)
u = (u << 10) + *i++ - UTF16_SURROGATE_OFFSET; // Assume it is a UTF-16 surrogate pair
return i;
}
template <class iterator> static iterator from_utf32(utf32_t u, iterator o)
{
if (u > 0xFFFF) { // Encode code points that do not fit in char_t as UTF-16 surrogate pairs
*o++ = static_cast<char_t>((u >> 10) + UTF16_SURROGATE_MIN - (0x10000 >> 10));
*o++ = static_cast<char_t>((u & 0x3FF) + UTF16_LOW_SURROGATE_MIN);
}
else
*o++ = static_cast<char_t>(u);
return o;
}
};
// Specialization of the traits for wchar_t
#include <cwctype>
template <> struct diff_match_patch_traits<wchar_t> : diff_match_patch_utf32_from_utf16<wchar_t> {
static bool is_alnum(wchar_t c) { return std::iswalnum(c)? true : false; }
static bool is_digit(wchar_t c) { return std::iswdigit(c)? true : false; }
static bool is_space(wchar_t c) { return std::iswspace(c)? true : false; }
static int to_int(const wchar_t* s) { return static_cast<int>(std::wcstol(s, nullptr, 10)); }
static wchar_t from_wchar(wchar_t c) { return c; }
static wchar_t to_wchar(wchar_t c) { return c; }
static const wchar_t* cs(const wchar_t* s) { return s; }
static const wchar_t eol = L'\n';
static const wchar_t tab = L'\t';
};
// Possible specialization of the traits for char
#include <cctype>
template <> struct diff_match_patch_traits<char> : diff_match_patch_utf32_direct<char>
{
static bool is_alnum(char c) { return std::isalnum(c)? true : false; }
static bool is_digit(char c) { return std::isdigit(c)? true : false; }
static bool is_space(char c) { return std::isspace(c)? true : false; }
static int to_int(const char* s) { return std::atoi(s); }
static char from_wchar(wchar_t c) { return static_cast<char>(c); }
static wchar_t to_wchar(char c) { return static_cast<wchar_t>(c); }
static std::string cs(const wchar_t* s) { return std::string(s, s + wcslen(s)); }
static const char eol = '\n';
static const char tab = '\t';
};
#endif // DIFF_MATCH_PATCH_H
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