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/*
* Copyright 2008 Google Inc. All Rights Reserved.
* Author: fraser@google.com (Neil Fraser)
* Author: mikeslemmer@gmail.com (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/
*/
#
include
<
algorithm
>
#
include
<
limits
>
//
Code known to compile and run with Qt 4.3 through Qt 4.7.
#
include
<
QtCore
>
#
include
<
time.h
>
#
include
"
diff_match_patch.h
"
//
////////////////////////
//
//
Diff Class
//
//
////////////////////////
/*
*
* Constructor. Initializes the diff with the provided values.
* @param operation One of INSERT, DELETE or EQUAL
* @param text The text being applied
*/
Diff::Diff
(Operation _operation,
const
QString &_text) :
operation(_operation), text(_text) {
//
Construct a diff with the specified operation and text.
}
Diff::Diff
() {
}
QString
Diff::strOperation
(Operation op) {
switch
(op) {
case
INSERT
:
return
"
INSERT
"
;
case
DELETE
:
return
"
DELETE
"
;
case
EQUAL
:
return
"
EQUAL
"
;
}
throw
"
Invalid operation.
"
;
}
/*
*
* Display a human-readable version of this Diff.
* @return text version
*/
QString
Diff::toString
()
const
{
QString prettyText = text;
//
Replace linebreaks with Pilcrow signs.
prettyText.
replace
(
'
\n
'
, L
'
\u00b6
'
);
return
QString
(
"
Diff(
"
) +
strOperation
(operation) +
QString
(
"
,
\"
"
)
+ prettyText +
QString
(
"
\"
)
"
);
}
/*
*
* Is this Diff equivalent to another Diff?
* @param d Another Diff to compare against
* @return true or false
*/
bool
Diff::
operator
==(
const
Diff &d)
const
{
return
(d.
operation
==
this
->
operation
) && (d.
text
==
this
->
text
);
}
bool
Diff::
operator
!=(
const
Diff &d)
const
{
return
!(
operator
== (d));
}
//
///////////////////////////////////////////
//
//
Patch Class
//
//
///////////////////////////////////////////
/*
*
* Constructor. Initializes with an empty list of diffs.
*/
Patch::Patch
() :
start1(
0
), start2(
0
),
length1(
0
), length2(
0
) {
}
bool
Patch::isNull
()
const
{
if
(start1 ==
0
&& start2 ==
0
&& length1 ==
0
&& length2 ==
0
&& diffs.
size
() ==
0
) {
return
true
;
}
return
false
;
}
/*
*
* Emmulate GNU diff's format.
* Header: @@ -382,8 +481,9 @@
* Indicies are printed as 1-based, not 0-based.
* @return The GNU diff string
*/
QString
Patch::toString
() {
QString coords1, coords2;
if
(length1 ==
0
) {
coords1 =
QString::number
(start1) +
QString
(
"
,0
"
);
}
else
if
(length1 ==
1
) {
coords1 =
QString::number
(start1 +
1
);
}
else
{
coords1 =
QString::number
(start1 +
1
) +
QString
(
"
,
"
)
+
QString::number
(length1);
}
if
(length2 ==
0
) {
coords2 =
QString::number
(start2) +
QString
(
"
,0
"
);
}
else
if
(length2 ==
1
) {
coords2 =
QString::number
(start2 +
1
);
}
else
{
coords2 =
QString::number
(start2 +
1
) +
QString
(
"
,
"
)
+
QString::number
(length2);
}
QString text;
text =
QString
(
"
@@ -
"
) + coords1 +
QString
(
"
+
"
) + coords2
+
QString
(
"
@@
\n
"
);
//
Escape the body of the patch with %xx notation.
foreach
(Diff aDiff, diffs) {
switch
(aDiff.
operation
) {
case
INSERT
:
text +=
QString
(
'
+
'
);
break
;
case
DELETE
:
text +=
QString
(
'
-
'
);
break
;
case
EQUAL
:
text +=
QString
(
'
'
);
break
;
}
text +=
QString
(
QUrl::toPercentEncoding
(aDiff.
text
,
"
!~*'();/?:@&=+$,#
"
))
+
QString
(
"
\n
"
);
}
return
text;
}
//
///////////////////////////////////////////
//
//
diff_match_patch Class
//
//
///////////////////////////////////////////
diff_match_patch::diff_match_patch
() :
Diff_Timeout(
1
.
0f
),
Diff_EditCost(
4
),
Match_Threshold(
0
.
5f
),
Match_Distance(
1000
),
Patch_DeleteThreshold(
0
.
5f
),
Patch_Margin(
4
),
Match_MaxBits(
32
) {
}
QList<Diff>
diff_match_patch::diff_main
(
const
QString &text1,
const
QString &text2) {
return
diff_main
(text1, text2,
true
);
}
QList<Diff>
diff_match_patch::diff_main
(
const
QString &text1,
const
QString &text2,
bool
checklines) {
//
Set a deadline by which time the diff must be complete.
clock_t
deadline;
if
(Diff_Timeout <=
0
) {
deadline = std::numeric_limits<
clock_t
>::
max
();
}
else
{
deadline =
clock
() + (
clock_t
)(Diff_Timeout *
CLOCKS_PER_SEC
);
}
return
diff_main
(text1, text2, checklines, deadline);
}
QList<Diff>
diff_match_patch::diff_main
(
const
QString &text1,
const
QString &text2,
bool
checklines,
clock_t
deadline) {
//
Check for null inputs.
if
(text1.
isNull
() || text2.
isNull
()) {
throw
"
Null inputs. (diff_main)
"
;
}
//
Check for equality (speedup).
QList<Diff> diffs;
if
(text1 == text2) {
if
(!text1.
isEmpty
()) {
diffs.
append
(
Diff
(
EQUAL
, text1));
}
return
diffs;
}
//
Trim off common prefix (speedup).
int
commonlength =
diff_commonPrefix
(text1, text2);
const
QString &commonprefix = text1.
left
(commonlength);
QString textChopped1 = text1.
mid
(commonlength);
QString textChopped2 = text2.
mid
(commonlength);
//
Trim off common suffix (speedup).
commonlength =
diff_commonSuffix
(textChopped1, textChopped2);
const
QString &commonsuffix = textChopped1.
right
(commonlength);
textChopped1 = textChopped1.
left
(textChopped1.
length
() - commonlength);
textChopped2 = textChopped2.
left
(textChopped2.
length
() - commonlength);
//
Compute the diff on the middle block.
diffs =
diff_compute
(textChopped1, textChopped2, checklines, deadline);
//
Restore the prefix and suffix.
if
(!commonprefix.
isEmpty
()) {
diffs.
prepend
(
Diff
(
EQUAL
, commonprefix));
}
if
(!commonsuffix.
isEmpty
()) {
diffs.
append
(
Diff
(
EQUAL
, commonsuffix));
}
diff_cleanupMerge
(diffs);
return
diffs;
}
QList<Diff>
diff_match_patch::diff_compute
(QString text1, QString text2,
bool
checklines,
clock_t
deadline) {
QList<Diff> diffs;
if
(text1.
isEmpty
()) {
//
Just add some text (speedup).
diffs.
append
(
Diff
(
INSERT
, text2));
return
diffs;
}
if
(text2.
isEmpty
()) {
//
Just delete some text (speedup).
diffs.
append
(
Diff
(
DELETE
, text1));
return
diffs;
}
{
const
QString longtext = text1.
length
() > text2.
length
() ? text1 : text2;
const
QString shorttext = text1.
length
() > text2.
length
() ? text2 : text1;
const
int
i = longtext.
indexOf
(shorttext);
if
(i != -
1
) {
//
Shorter text is inside the longer text (speedup).
const
Operation op = (text1.
length
() > text2.
length
()) ?
DELETE
:
INSERT
;
diffs.
append
(
Diff
(op, longtext.
left
(i)));
diffs.
append
(
Diff
(
EQUAL
, shorttext));
diffs.
append
(
Diff
(op,
safeMid
(longtext, i + shorttext.
length
())));
return
diffs;
}
if
(shorttext.
length
() ==
1
) {
//
Single character string.
//
After the previous speedup, the character can't be an equality.
diffs.
append
(
Diff
(
DELETE
, text1));
diffs.
append
(
Diff
(
INSERT
, text2));
return
diffs;
}
//
Garbage collect longtext and shorttext by scoping out.
}
//
Check to see if the problem can be split in two.
const
QStringList hm =
diff_halfMatch
(text1, text2);
if
(hm.
count
() >
0
) {
//
A half-match was found, sort out the return data.
const
QString text1_a = hm[
0
];
const
QString text1_b = hm[
1
];
const
QString text2_a = hm[
2
];
const
QString text2_b = hm[
3
];
const
QString mid_common = hm[
4
];
//
Send both pairs off for separate processing.
const
QList<Diff> diffs_a =
diff_main
(text1_a, text2_a,
checklines, deadline);
const
QList<Diff> diffs_b =
diff_main
(text1_b, text2_b,
checklines, deadline);
//
Merge the results.
diffs = diffs_a;
diffs.
append
(
Diff
(
EQUAL
, mid_common));
diffs += diffs_b;
return
diffs;
}
//
Perform a real diff.
if
(checklines && text1.
length
() >
100
&& text2.
length
() >
100
) {
return
diff_lineMode
(text1, text2, deadline);
}
return
diff_bisect
(text1, text2, deadline);
}
QList<Diff>
diff_match_patch::diff_lineMode
(QString text1, QString text2,
clock_t
deadline) {
//
Scan the text on a line-by-line basis first.
const
QList<QVariant> b =
diff_linesToChars
(text1, text2);
text1 = b[
0
].
toString
();
text2 = b[
1
].
toString
();
QStringList linearray = b[
2
].
toStringList
();
QList<Diff> diffs =
diff_main
(text1, text2,
false
, deadline);
//
Convert the diff back to original text.
diff_charsToLines
(diffs, linearray);
//
Eliminate freak matches (e.g. blank lines)
diff_cleanupSemantic
(diffs);
//
Rediff any replacement blocks, this time character-by-character.
//
Add a dummy entry at the end.
diffs.
append
(
Diff
(
EQUAL
,
"
"
));
int
count_delete =
0
;
int
count_insert =
0
;
QString text_delete =
"
"
;
QString text_insert =
"
"
;
QMutableListIterator<Diff>
pointer
(diffs);
Diff *thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
while
(thisDiff !=
NULL
) {
switch
(thisDiff->
operation
) {
case
INSERT
:
count_insert++;
text_insert += thisDiff->
text
;
break
;
case
DELETE
:
count_delete++;
text_delete += thisDiff->
text
;
break
;
case
EQUAL
:
//
Upon reaching an equality, check for prior redundancies.
if
(count_delete >=
1
&& count_insert >=
1
) {
//
Delete the offending records and add the merged ones.
pointer.
previous
();
for
(
int
j =
0
; j < count_delete + count_insert; j++) {
pointer.
previous
();
pointer.
remove
();
}
foreach
(Diff newDiff,
diff_main
(text_delete, text_insert,
false
, deadline)) {
pointer.
insert
(newDiff);
}
}
count_insert =
0
;
count_delete =
0
;
text_delete =
"
"
;
text_insert =
"
"
;
break
;
}
thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
}
diffs.
removeLast
();
//
Remove the dummy entry at the end.
return
diffs;
}
QList<Diff>
diff_match_patch::diff_bisect
(
const
QString &text1,
const
QString &text2,
clock_t
deadline) {
//
Cache the text lengths to prevent multiple calls.
const
int
text1_length = text1.
length
();
const
int
text2_length = text2.
length
();
const
int
max_d = (text1_length + text2_length +
1
) /
2
;
const
int
v_offset = max_d;
const
int
v_length =
2
* max_d;
int
*v1 =
new
int
[v_length];
int
*v2 =
new
int
[v_length];
for
(
int
x =
0
; x < v_length; x++) {
v1[x] = -
1
;
v2[x] = -
1
;
}
v1[v_offset +
1
] =
0
;
v2[v_offset +
1
] =
0
;
const
int
delta = text1_length - text2_length;
//
If the total number of characters is odd, then the front path will
//
collide with the reverse path.
const
bool
front = (delta %
2
!=
0
);
//
Offsets for start and end of k loop.
//
Prevents mapping of space beyond the grid.
int
k1start =
0
;
int
k1end =
0
;
int
k2start =
0
;
int
k2end =
0
;
for
(
int
d =
0
; d < max_d; d++) {
//
Bail out if deadline is reached.
if
(
clock
() > deadline) {
break
;
}
//
Walk the front path one step.
for
(
int
k1 = -d + k1start; k1 <= d - k1end; k1 +=
2
) {
const
int
k1_offset = v_offset + k1;
int
x1;
if
(k1 == -d || (k1 != d && v1[k1_offset -
1
] < v1[k1_offset +
1
])) {
x1 = v1[k1_offset +
1
];
}
else
{
x1 = v1[k1_offset -
1
] +
1
;
}
int
y1 = x1 - k1;
while
(x1 < text1_length && y1 < text2_length
&& text1[x1] == text2[y1]) {
x1++;
y1++;
}
v1[k1_offset] = x1;
if
(x1 > text1_length) {
//
Ran off the right of the graph.
k1end +=
2
;
}
else
if
(y1 > text2_length) {
//
Ran off the bottom of the graph.
k1start +=
2
;
}
else
if
(front) {
int
k2_offset = v_offset + delta - k1;
if
(k2_offset >=
0
&& k2_offset < v_length && v2[k2_offset] != -
1
) {
//
Mirror x2 onto top-left coordinate system.
int
x2 = text1_length - v2[k2_offset];
if
(x1 >= x2) {
//
Overlap detected.
delete []
v1;
delete []
v2;
return
diff_bisectSplit
(text1, text2, x1, y1, deadline);
}
}
}
}
//
Walk the reverse path one step.
for
(
int
k2 = -d + k2start; k2 <= d - k2end; k2 +=
2
) {
const
int
k2_offset = v_offset + k2;
int
x2;
if
(k2 == -d || (k2 != d && v2[k2_offset -
1
] < v2[k2_offset +
1
])) {
x2 = v2[k2_offset +
1
];
}
else
{
x2 = v2[k2_offset -
1
] +
1
;
}
int
y2 = x2 - k2;
while
(x2 < text1_length && y2 < text2_length
&& text1[text1_length - x2 -
1
] == text2[text2_length - y2 -
1
]) {
x2++;
y2++;
}
v2[k2_offset] = x2;
if
(x2 > text1_length) {
//
Ran off the left of the graph.
k2end +=
2
;
}
else
if
(y2 > text2_length) {
//
Ran off the top of the graph.
k2start +=
2
;
}
else
if
(!front) {
int
k1_offset = v_offset + delta - k2;
if
(k1_offset >=
0
&& k1_offset < v_length && v1[k1_offset] != -
1
) {
int
x1 = v1[k1_offset];
int
y1 = v_offset + x1 - k1_offset;
//
Mirror x2 onto top-left coordinate system.
x2 = text1_length - x2;
if
(x1 >= x2) {
//
Overlap detected.
delete []
v1;
delete []
v2;
return
diff_bisectSplit
(text1, text2, x1, y1, deadline);
}
}
}
}
}
delete []
v1;
delete []
v2;
//
Diff took too long and hit the deadline or
//
number of diffs equals number of characters, no commonality at all.
QList<Diff> diffs;
diffs.
append
(
Diff
(
DELETE
, text1));
diffs.
append
(
Diff
(
INSERT
, text2));
return
diffs;
}
QList<Diff>
diff_match_patch::diff_bisectSplit
(
const
QString &text1,
const
QString &text2,
int
x,
int
y,
clock_t
deadline) {
QString text1a = text1.
left
(x);
QString text2a = text2.
left
(y);
QString text1b =
safeMid
(text1, x);
QString text2b =
safeMid
(text2, y);
//
Compute both diffs serially.
QList<Diff> diffs =
diff_main
(text1a, text2a,
false
, deadline);
QList<Diff> diffsb =
diff_main
(text1b, text2b,
false
, deadline);
return
diffs + diffsb;
}
QList<QVariant>
diff_match_patch::diff_linesToChars
(
const
QString &text1,
const
QString &text2) {
QStringList lineArray;
QMap<QString,
int
> lineHash;
//
e.g. linearray[4] == "Hello\n"
//
e.g. linehash.get("Hello\n") == 4
//
"\x00" is a valid character, but various debuggers don't like it.
//
So we'll insert a junk entry to avoid generating a null character.
lineArray.
append
(
"
"
);
const
QString chars1 =
diff_linesToCharsMunge
(text1, lineArray, lineHash);
const
QString chars2 =
diff_linesToCharsMunge
(text2, lineArray, lineHash);
QList<QVariant> listRet;
listRet.
append
(
QVariant::fromValue
(chars1));
listRet.
append
(
QVariant::fromValue
(chars2));
listRet.
append
(
QVariant::fromValue
(lineArray));
return
listRet;
}
QString
diff_match_patch::diff_linesToCharsMunge
(
const
QString &text,
QStringList &lineArray,
QMap<QString,
int
> &lineHash) {
int
lineStart =
0
;
int
lineEnd = -
1
;
QString line;
QString chars;
//
Walk the text, pulling out a substring for each line.
//
text.split('\n') would would temporarily double our memory footprint.
//
Modifying text would create many large strings to garbage collect.
while
(lineEnd < text.
length
() -
1
) {
lineEnd = text.
indexOf
(
'
\n
'
, lineStart);
if
(lineEnd == -
1
) {
lineEnd = text.
length
() -
1
;
}
line =
safeMid
(text, lineStart, lineEnd +
1
- lineStart);
lineStart = lineEnd +
1
;
if
(lineHash.
contains
(line)) {
chars +=
QChar
(
static_cast
<ushort>(lineHash.
value
(line)));
}
else
{
lineArray.
append
(line);
lineHash.
insert
(line, lineArray.
size
() -
1
);
chars +=
QChar
(
static_cast
<ushort>(lineArray.
size
() -
1
));
}
}
return
chars;
}
void
diff_match_patch::diff_charsToLines
(QList<Diff> &diffs,
const
QStringList &lineArray) {
//
Qt has no mutable foreach construct.
QMutableListIterator<Diff>
i
(diffs);
while
(i.
hasNext
()) {
Diff &diff = i.
next
();
QString text;
for
(
int
y =
0
; y < diff.
text
.
length
(); y++) {
text += lineArray.
value
(
static_cast
<ushort>(diff.
text
[y].
unicode
()));
}
diff.
text
= text;
}
}
int
diff_match_patch::diff_commonPrefix
(
const
QString &text1,
const
QString &text2) {
//
Performance analysis: http://neil.fraser.name/news/2007/10/09/
const
int
n =
std::min
(text1.
length
(), text2.
length
());
for
(
int
i =
0
; i < n; i++) {
if
(text1[i] != text2[i]) {
return
i;
}
}
return
n;
}
int
diff_match_patch::diff_commonSuffix
(
const
QString &text1,
const
QString &text2) {
//
Performance analysis: http://neil.fraser.name/news/2007/10/09/
const
int
text1_length = text1.
length
();
const
int
text2_length = text2.
length
();
const
int
n =
std::min
(text1_length, text2_length);
for
(
int
i =
1
; i <= n; i++) {
if
(text1[text1_length - i] != text2[text2_length - i]) {
return
i -
1
;
}
}
return
n;
}
int
diff_match_patch::diff_commonOverlap
(
const
QString &text1,
const
QString &text2) {
//
Cache the text lengths to prevent multiple calls.
const
int
text1_length = text1.
length
();
const
int
text2_length = text2.
length
();
//
Eliminate the null case.
if
(text1_length ==
0
|| text2_length ==
0
) {
return
0
;
}
//
Truncate the longer string.
QString text1_trunc = text1;
QString text2_trunc = text2;
if
(text1_length > text2_length) {
text1_trunc = text1.
right
(text2_length);
}
else
if
(text1_length < text2_length) {
text2_trunc = text2.
left
(text1_length);
}
const
int
text_length =
std::min
(text1_length, text2_length);
//
Quick check for the worst case.
if
(text1_trunc == text2_trunc) {
return
text_length;
}
//
Start by looking for a single character match
//
and increase length until no match is found.
//
Performance analysis: http://neil.fraser.name/news/2010/11/04/
int
best =
0
;
int
length =
1
;
while
(
true
) {
QString pattern = text1_trunc.
right
(length);
int
found = text2_trunc.
indexOf
(pattern);
if
(found == -
1
) {
return
best;
}
length += found;
if
(found ==
0
|| text1_trunc.
right
(length) == text2_trunc.
left
(length)) {
best = length;
length++;
}
}
}
QStringList
diff_match_patch::diff_halfMatch
(
const
QString &text1,
const
QString &text2) {
if
(Diff_Timeout <=
0
) {
//
Don't risk returning a non-optimal diff if we have unlimited time.
return
QStringList
();
}
const
QString longtext = text1.
length
() > text2.
length
() ? text1 : text2;
const
QString shorttext = text1.
length
() > text2.
length
() ? text2 : text1;
if
(longtext.
length
() <
4
|| shorttext.
length
() *
2
< longtext.
length
()) {
return
QStringList
();
//
Pointless.
}
//
First check if the second quarter is the seed for a half-match.
const
QStringList hm1 =
diff_halfMatchI
(longtext, shorttext,
(longtext.
length
() +
3
) /
4
);
//
Check again based on the third quarter.
const
QStringList hm2 =
diff_halfMatchI
(longtext, shorttext,
(longtext.
length
() +
1
) /
2
);
QStringList hm;
if
(hm1.
isEmpty
() && hm2.
isEmpty
()) {
return
QStringList
();
}
else
if
(hm2.
isEmpty
()) {
hm = hm1;
}
else
if
(hm1.
isEmpty
()) {
hm = hm2;
}
else
{
//
Both matched. Select the longest.
hm = hm1[
4
].
length
() > hm2[
4
].
length
() ? hm1 : hm2;
}
//
A half-match was found, sort out the return data.
if
(text1.
length
() > text2.
length
()) {
return
hm;
}
else
{
QStringList listRet;
listRet << hm[
2
] << hm[
3
] << hm[
0
] << hm[
1
] << hm[
4
];
return
listRet;
}
}
QStringList
diff_match_patch::diff_halfMatchI
(
const
QString &longtext,
const
QString &shorttext,
int
i) {
//
Start with a 1/4 length substring at position i as a seed.
const
QString seed =
safeMid
(longtext, i, longtext.
length
() /
4
);
int
j = -
1
;
QString best_common;
QString best_longtext_a, best_longtext_b;
QString best_shorttext_a, best_shorttext_b;
while
((j = shorttext.
indexOf
(seed, j +
1
)) != -
1
) {
const
int
prefixLength =
diff_commonPrefix
(
safeMid
(longtext, i),
safeMid
(shorttext, j));
const
int
suffixLength =
diff_commonSuffix
(longtext.
left
(i),
shorttext.
left
(j));
if
(best_common.
length
() < suffixLength + prefixLength) {
best_common =
safeMid
(shorttext, j - suffixLength, suffixLength)
+
safeMid
(shorttext, j, prefixLength);
best_longtext_a = longtext.
left
(i - suffixLength);
best_longtext_b =
safeMid
(longtext, i + prefixLength);
best_shorttext_a = shorttext.
left
(j - suffixLength);
best_shorttext_b =
safeMid
(shorttext, j + prefixLength);
}
}
if
(best_common.
length
() *
2
>= longtext.
length
()) {
QStringList listRet;
listRet << best_longtext_a << best_longtext_b << best_shorttext_a
<< best_shorttext_b << best_common;
return
listRet;
}
else
{
return
QStringList
();
}
}
void
diff_match_patch::diff_cleanupSemantic
(QList<Diff> &diffs) {
if
(diffs.
isEmpty
()) {
return
;
}
bool
changes =
false
;
QStack<Diff> equalities;
//
Stack of equalities.
QString lastequality;
//
Always equal to equalities.lastElement().text
QMutableListIterator<Diff>
pointer
(diffs);
//
Number of characters that changed prior to the equality.
int
length_insertions1 =
0
;
int
length_deletions1 =
0
;
//
Number of characters that changed after the equality.
int
length_insertions2 =
0
;
int
length_deletions2 =
0
;
Diff *thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
while
(thisDiff !=
NULL
) {
if
(thisDiff->
operation
==
EQUAL
) {
//
Equality found.
equalities.
push
(*thisDiff);
length_insertions1 = length_insertions2;
length_deletions1 = length_deletions2;
length_insertions2 =
0
;
length_deletions2 =
0
;
lastequality = thisDiff->
text
;
}
else
{
//
An insertion or deletion.
if
(thisDiff->
operation
==
INSERT
) {
length_insertions2 += thisDiff->
text
.
length
();
}
else
{
length_deletions2 += thisDiff->
text
.
length
();
}
//
Eliminate an equality that is smaller or equal to the edits on both
//
sides of it.
if
(!lastequality.
isNull
()
&& (lastequality.
length
()
<=
std::max
(length_insertions1, length_deletions1))
&& (lastequality.
length
()
<=
std::max
(length_insertions2, length_deletions2))) {
//
printf("Splitting: '%s'\n", qPrintable(lastequality));
//
Walk back to offending equality.
while
(*thisDiff != equalities.
top
()) {
thisDiff = &pointer.
previous
();
}
pointer.
next
();
//
Replace equality with a delete.
pointer.
setValue
(
Diff
(
DELETE
, lastequality));
//
Insert a corresponding an insert.
pointer.
insert
(
Diff
(
INSERT
, lastequality));
equalities.
pop
();
//
Throw away the equality we just deleted.
if
(!equalities.
isEmpty
()) {
//
Throw away the previous equality (it needs to be reevaluated).
equalities.
pop
();
}
if
(equalities.
isEmpty
()) {
//
There are no previous equalities, walk back to the start.
while
(pointer.
hasPrevious
()) {
pointer.
previous
();
}
}
else
{
//
There is a safe equality we can fall back to.
thisDiff = &equalities.
top
();
while
(*thisDiff != pointer.
previous
()) {
//
Intentionally empty loop.
}
}
length_insertions1 =
0
;
//
Reset the counters.
length_deletions1 =
0
;
length_insertions2 =
0
;
length_deletions2 =
0
;
lastequality =
QString
();
changes =
true
;
}
}
thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
}
//
Normalize the diff.
if
(changes) {
diff_cleanupMerge
(diffs);
}
diff_cleanupSemanticLossless
(diffs);
//
Find any overlaps between deletions and insertions.
//
e.g: <del>abcxxx</del><ins>xxxdef</ins>
//
-> <del>abc</del>xxx<ins>def</ins>
//
e.g: <del>xxxabc</del><ins>defxxx</ins>
//
-> <ins>def</ins>xxx<del>abc</del>
//
Only extract an overlap if it is as big as the edit ahead or behind it.
pointer.
toFront
();
Diff *prevDiff =
NULL
;
thisDiff =
NULL
;
if
(pointer.
hasNext
()) {
prevDiff = &pointer.
next
();
if
(pointer.
hasNext
()) {
thisDiff = &pointer.
next
();
}
}
while
(thisDiff !=
NULL
) {
if
(prevDiff->
operation
==
DELETE
&&
thisDiff->
operation
==
INSERT
) {
QString deletion = prevDiff->
text
;
QString insertion = thisDiff->
text
;
int
overlap_length1 =
diff_commonOverlap
(deletion, insertion);
int
overlap_length2 =
diff_commonOverlap
(insertion, deletion);
if
(overlap_length1 >= overlap_length2) {
if
(overlap_length1 >= deletion.
length
() /
2.0
||
overlap_length1 >= insertion.
length
() /
2.0
) {
//
Overlap found. Insert an equality and trim the surrounding edits.
pointer.
previous
();
pointer.
insert
(
Diff
(
EQUAL
, insertion.
left
(overlap_length1)));
prevDiff->
text
=
deletion.
left
(deletion.
length
() - overlap_length1);
thisDiff->
text
=
safeMid
(insertion, overlap_length1);
//
pointer.insert inserts the element before the cursor, so there is
//
no need to step past the new element.
}
}
else
{
if
(overlap_length2 >= deletion.
length
() /
2.0
||
overlap_length2 >= insertion.
length
() /
2.0
) {
//
Reverse overlap found.
//
Insert an equality and swap and trim the surrounding edits.
pointer.
previous
();
pointer.
insert
(
Diff
(
EQUAL
, deletion.
left
(overlap_length2)));
prevDiff->
operation
=
INSERT
;
prevDiff->
text
=
insertion.
left
(insertion.
length
() - overlap_length2);
thisDiff->
operation
=
DELETE
;
thisDiff->
text
=
safeMid
(deletion, overlap_length2);
//
pointer.insert inserts the element before the cursor, so there is
//
no need to step past the new element.
}
}
thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
}
prevDiff = thisDiff;
thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
}
}
void
diff_match_patch::diff_cleanupSemanticLossless
(QList<Diff> &diffs) {
QString equality1, edit, equality2;
QString commonString;
int
commonOffset;
int
score, bestScore;
QString bestEquality1, bestEdit, bestEquality2;
//
Create a new iterator at the start.
QMutableListIterator<Diff>
pointer
(diffs);
Diff *prevDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
Diff *thisDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
Diff *nextDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
//
Intentionally ignore the first and last element (don't need checking).
while
(nextDiff !=
NULL
) {
if
(prevDiff->
operation
==
EQUAL
&&
nextDiff->
operation
==
EQUAL
) {
//
This is a single edit surrounded by equalities.
equality1 = prevDiff->
text
;
edit = thisDiff->
text
;
equality2 = nextDiff->
text
;
//
First, shift the edit as far left as possible.
commonOffset =
diff_commonSuffix
(equality1, edit);
if
(commonOffset !=
0
) {
commonString =
safeMid
(edit, edit.
length
() - commonOffset);
equality1 = equality1.
left
(equality1.
length
() - commonOffset);
edit = commonString + edit.
left
(edit.
length
() - commonOffset);
equality2 = commonString + equality2;
}
//
Second, step character by character right, looking for the best fit.
bestEquality1 = equality1;
bestEdit = edit;
bestEquality2 = equality2;
bestScore =
diff_cleanupSemanticScore
(equality1, edit)
+
diff_cleanupSemanticScore
(edit, equality2);
while
(!edit.
isEmpty
() && !equality2.
isEmpty
()
&& edit[
0
] == equality2[
0
]) {
equality1 += edit[
0
];
edit =
safeMid
(edit,
1
) + equality2[
0
];
equality2 =
safeMid
(equality2,
1
);
score =
diff_cleanupSemanticScore
(equality1, edit)
+
diff_cleanupSemanticScore
(edit, equality2);
//
The >= encourages trailing rather than leading whitespace on edits.
if
(score >= bestScore) {
bestScore = score;
bestEquality1 = equality1;
bestEdit = edit;
bestEquality2 = equality2;
}
}
if
(prevDiff->
text
!= bestEquality1) {
//
We have an improvement, save it back to the diff.
if
(!bestEquality1.
isEmpty
()) {
prevDiff->
text
= bestEquality1;
}
else
{
pointer.
previous
();
//
Walk past nextDiff.
pointer.
previous
();
//
Walk past thisDiff.
pointer.
previous
();
//
Walk past prevDiff.
pointer.
remove
();
//
Delete prevDiff.
pointer.
next
();
//
Walk past thisDiff.
pointer.
next
();
//
Walk past nextDiff.
}
thisDiff->
text
= bestEdit;
if
(!bestEquality2.
isEmpty
()) {
nextDiff->
text
= bestEquality2;
}
else
{
pointer.
remove
();
//
Delete nextDiff.
nextDiff = thisDiff;
thisDiff = prevDiff;
}
}
}
prevDiff = thisDiff;
thisDiff = nextDiff;
nextDiff = pointer.
hasNext
() ? &pointer.
next
() :
NULL
;
}
}
int
diff_match_patch::diff_cleanupSemanticScore
(
const
QString &one,
const
QString &two) {
if
(one.
isEmpty
() || two.
isEmpty
()) {
//
Edges are the best.
return
6
;
}
//
Each port of this function behaves slightly differently due to
//
subtle differences in each language's definition of things like
//
'whitespace'. Since this function's purpose is largely cosmetic,
//
the choice has been made to use each language's native features
//
rather than force total conformity.
QChar char1 = one[one.
length
() -
1
];
QChar char2 = two[
0
];
bool
nonAlphaNumeric1 = !char1.
isLetterOrNumber
();
bool
nonAlphaNumeric2 = !char2.
isLetterOrNumber
();
bool
whitespace1 = nonAlphaNumeric1 && char1.
isSpace
();
bool
whitespace2 = nonAlphaNumeric2 && char2.
isSpace
();
bool
lineBreak1 = whitespace1 && char1.
category
() == QChar::Other_Control;
bool
lineBreak2 = whitespace2 && char2.
category
() == QChar::Other_Control;
bool
blankLine1 = lineBreak1 &&
BLANKLINEEND
.
indexIn
(one) != -
1
;
bool
blankLine2 = lineBreak2 &&
BLANKLINESTART
.
indexIn
(two) != -
1
;
if
(blankLine1 || blankLine2) {
//
Five points for blank lines.
return
5
;
}
else
if
(lineBreak1 || lineBreak2) {
//
Four points for line breaks.
return
4
;
}
else
if
(nonAlphaNumeric1 && !whitespace1 && whitespace2) {
//
Three points for end of sentences.
return
3
;
}
else
if
(whitespace1 || whitespace2) {
//
Two points for whitespace.
return
2
;
}
else
if
(nonAlphaNumeric1 || nonAlphaNumeric2) {
//
One point for non-alphanumeric.
return
1
;
}
return
0
;
}
//
Define some regex patterns for matching boundaries.
QRegExp diff_match_patch::
BLANKLINEEND
= QRegExp(
"
\\
n
\\
r?
\\
n$
"
);
QRegExp diff_match_patch::
BLANKLINESTART
= QRegExp(
"
^
\\
r?
\\
n
\\
r?
\\
n
"
);
void
diff_match_patch::diff_cleanupEfficiency
(QList<Diff> &diffs) {
if
(diffs.
isEmpty
()) {
return
;
}
bool
changes =
false
;
QStack<Diff> equalities;
//
Stack of equalities.
QString lastequality;
//
Always equal to equalities.lastElement().text
QMutableListIterator<Diff>
pointer
(diffs);
//
Is there an insertion operation before the last equality.
bool
pre_ins =
false
;
//
Is there a deletion operation before the last equality.
bool
pre_del =
false
;
//
Is there an insertion operation after the last equality.
View remainder of file in raw view
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