all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
blob 1aa6c05662a446a8471e8c0150a4d4a23510c0b7 92173 bytes (raw)
name: lisp/vc/diff-mode.el 	 # note: path name is non-authoritative(*)

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
 
;;; diff-mode.el --- a mode for viewing/editing context diffs -*- lexical-binding: t -*-

;; Copyright (C) 1998-2017 Free Software Foundation, Inc.

;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
;; Keywords: convenience patch diff vc

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Provides support for font-lock, outline, navigation
;; commands, editing and various conversions as well as jumping
;; to the corresponding source file.

;; Inspired by Pavel Machek's patch-mode.el (<pavel@@atrey.karlin.mff.cuni.cz>)
;; Some efforts were spent to have it somewhat compatible with XEmacs's
;; diff-mode as well as with compilation-minor-mode

;; Bugs:

;; - Reverse doesn't work with normal diffs.

;; Todo:

;; - Improve `diff-add-change-log-entries-other-window',
;;   it is very simplistic now.
;;
;; - Add a `delete-after-apply' so C-c C-a automatically deletes hunks.
;;   Also allow C-c C-a to delete already-applied hunks.
;;
;; - Try `diff <file> <hunk>' to try and fuzzily discover the source location
;;   of a hunk.  Show then the changes between <file> and <hunk> and make it
;;   possible to apply them to <file>, <hunk-src>, or <hunk-dst>.
;;   Or maybe just make it into a ".rej to diff3-markers converter".
;;   Maybe just use `wiggle' (by Neil Brown) to do it for us.
;;
;; - in diff-apply-hunk, strip context in replace-match to better
;;   preserve markers and spacing.
;; - Handle `diff -b' output in context->unified.

;;; Code:
(eval-when-compile (require 'cl-lib))

(defvar add-log-buffer-file-name-function)


(defgroup diff-mode ()
  "Major mode for viewing/editing diffs."
  :version "21.1"
  :group 'tools
  :group 'diff)

(defcustom diff-default-read-only nil
  "If non-nil, `diff-mode' buffers default to being read-only."
  :type 'boolean
  :group 'diff-mode)

(defcustom diff-jump-to-old-file nil
  "Non-nil means `diff-goto-source' jumps to the old file.
Else, it jumps to the new file."
  :type 'boolean
  :group 'diff-mode)

(defcustom diff-update-on-the-fly t
  "Non-nil means hunk headers are kept up-to-date on-the-fly.
When editing a diff file, the line numbers in the hunk headers
need to be kept consistent with the actual diff.  This can
either be done on the fly (but this sometimes interacts poorly with the
undo mechanism) or whenever the file is written (can be slow
when editing big diffs)."
  :type 'boolean
  :group 'diff-mode)

(defcustom diff-advance-after-apply-hunk t
  "Non-nil means `diff-apply-hunk' will move to the next hunk after applying."
  :type 'boolean
  :group 'diff-mode)

(defcustom diff-mode-hook nil
  "Run after setting up the `diff-mode' major mode."
  :type 'hook
  :options '(diff-delete-empty-files diff-make-unified)
  :group 'diff-mode)

(defvar diff-vc-backend nil
  "The VC backend that created the current Diff buffer, if any.")

(defvar diff-outline-regexp
  "\\([*+][*+][*+] [^0-9]\\|@@ ...\\|\\*\\*\\* [0-9].\\|--- [0-9]..\\)")

;;;;
;;;; keymap, menu, ...
;;;;

(easy-mmode-defmap diff-mode-shared-map
  '(("n" . diff-hunk-next)
    ("N" . diff-file-next)
    ("p" . diff-hunk-prev)
    ("P" . diff-file-prev)
    ("\t" . diff-hunk-next)
    ([backtab] . diff-hunk-prev)
    ("k" . diff-hunk-kill)
    ("K" . diff-file-kill)
    ("}" . diff-file-next)	; From compilation-minor-mode.
    ("{" . diff-file-prev)
    ("\C-m" . diff-goto-source)
    ([mouse-2] . diff-goto-source)
    ("W" . widen)
    ("o" . diff-goto-source)	; other-window
    ("A" . diff-ediff-patch)
    ("r" . diff-restrict-view)
    ("R" . diff-reverse-direction)
    ([remap undo] . diff-undo))
  "Basic keymap for `diff-mode', bound to various prefix keys."
  :inherit special-mode-map)

(easy-mmode-defmap diff-mode-map
  `(("\e" . ,(let ((map (make-sparse-keymap)))
               ;; We want to inherit most bindings from diff-mode-shared-map,
               ;; but not all since they may hide useful M-<foo> global
               ;; bindings when editing.
               (set-keymap-parent map diff-mode-shared-map)
               (dolist (key '("A" "r" "R" "g" "q" "W" "z"))
                 (define-key map key nil))
               map))
    ;; From compilation-minor-mode.
    ("\C-c\C-c" . diff-goto-source)
    ;; By analogy with the global C-x 4 a binding.
    ("\C-x4A" . diff-add-change-log-entries-other-window)
    ;; Misc operations.
    ("\C-c\C-a" . diff-apply-hunk)
    ("\C-c\C-e" . diff-ediff-patch)
    ("\C-c\C-n" . diff-restrict-view)
    ("\C-c\C-s" . diff-split-hunk)
    ("\C-c\C-t" . diff-test-hunk)
    ("\C-c\C-r" . diff-reverse-direction)
    ("\C-c\C-u" . diff-context->unified)
    ;; `d' because it duplicates the context :-(  --Stef
    ("\C-c\C-d" . diff-unified->context)
    ("\C-c\C-w" . diff-ignore-whitespace-hunk)
    ("\C-c\C-b" . diff-refine-hunk)  ;No reason for `b' :-(
    ("\C-c\C-f" . next-error-follow-minor-mode))
  "Keymap for `diff-mode'.  See also `diff-mode-shared-map'.")

(easy-menu-define diff-mode-menu diff-mode-map
  "Menu for `diff-mode'."
  '("Diff"
    ["Jump to Source"		diff-goto-source
     :help "Jump to the corresponding source line"]
    ["Apply hunk"		diff-apply-hunk
     :help "Apply the current hunk to the source file and go to the next"]
    ["Test applying hunk"	diff-test-hunk
     :help "See whether it's possible to apply the current hunk"]
    ["Apply diff with Ediff"	diff-ediff-patch
     :help "Call `ediff-patch-file' on the current buffer"]
    ["Create Change Log entries" diff-add-change-log-entries-other-window
     :help "Create ChangeLog entries for the changes in the diff buffer"]
    "-----"
    ["Reverse direction"	diff-reverse-direction
     :help "Reverse the direction of the diffs"]
    ["Context -> Unified"	diff-context->unified
     :help "Convert context diffs to unified diffs"]
    ["Unified -> Context"	diff-unified->context
     :help "Convert unified diffs to context diffs"]
    ;;["Fixup Headers"		diff-fixup-modifs	(not buffer-read-only)]
    ["Remove trailing whitespace" diff-delete-trailing-whitespace
     :help "Remove trailing whitespace problems introduced by the diff"]
    ["Show trailing whitespace" whitespace-mode
     :style toggle :selected (bound-and-true-p whitespace-mode)
     :help "Show trailing whitespace in modified lines"]
    "-----"
    ["Split hunk"		diff-split-hunk
     :active (diff-splittable-p)
     :help "Split the current (unified diff) hunk at point into two hunks"]
    ["Ignore whitespace changes" diff-ignore-whitespace-hunk
     :help "Re-diff the current hunk, ignoring whitespace differences"]
    ["Highlight fine changes"	diff-refine-hunk
     :help "Highlight changes of hunk at point at a finer granularity"]
    ["Kill current hunk"	diff-hunk-kill
     :help "Kill current hunk"]
    ["Kill current file's hunks" diff-file-kill
     :help "Kill all current file's hunks"]
    "-----"
    ["Previous Hunk"		diff-hunk-prev
     :help "Go to the previous count'th hunk"]
    ["Next Hunk"		diff-hunk-next
     :help "Go to the next count'th hunk"]
    ["Previous File"		diff-file-prev
     :help "Go to the previous count'th file"]
    ["Next File"		diff-file-next
     :help "Go to the next count'th file"]
    ))

(defcustom diff-minor-mode-prefix "\C-c="
  "Prefix key for `diff-minor-mode' commands."
  :type '(choice (string "\e") (string "C-c=") string)
  :group 'diff-mode)

(easy-mmode-defmap diff-minor-mode-map
  `((,diff-minor-mode-prefix . ,diff-mode-shared-map))
  "Keymap for `diff-minor-mode'.  See also `diff-mode-shared-map'.")

(define-minor-mode diff-auto-refine-mode
  "Toggle automatic diff hunk highlighting (Diff Auto Refine mode).
With a prefix argument ARG, enable Diff Auto Refine mode if ARG
is positive, and disable it otherwise.  If called from Lisp,
enable the mode if ARG is omitted or nil.

Diff Auto Refine mode is a buffer-local minor mode used with
`diff-mode'.  When enabled, Emacs automatically highlights
changes in detail as the user visits hunks.  When transitioning
from disabled to enabled, it tries to refine the current hunk, as
well."
  :group 'diff-mode :init-value t :lighter nil ;; " Auto-Refine"
  (when diff-auto-refine-mode
    (condition-case-unless-debug nil (diff-refine-hunk) (error nil))))

;;;;
;;;; font-lock support
;;;;

(defface diff-header
  '((((class color) (min-colors 88) (background light))
     :background "grey80")
    (((class color) (min-colors 88) (background dark))
     :background "grey45")
    (((class color))
     :foreground "blue1" :weight bold)
    (t :weight bold))
  "`diff-mode' face inherited by hunk and index header faces."
  :group 'diff-mode)

(defface diff-file-header
  '((((class color) (min-colors 88) (background light))
     :background "grey70" :weight bold)
    (((class color) (min-colors 88) (background dark))
     :background "grey60" :weight bold)
    (((class color))
     :foreground "cyan" :weight bold)
    (t :weight bold))			; :height 1.3
  "`diff-mode' face used to highlight file header lines."
  :group 'diff-mode)

(defface diff-index
  '((t :inherit diff-file-header))
  "`diff-mode' face used to highlight index header lines."
  :group 'diff-mode)

(defface diff-hunk-header
  '((t :inherit diff-header))
  "`diff-mode' face used to highlight hunk header lines."
  :group 'diff-mode)

(defface diff-removed
  '((default
     :inherit diff-changed)
    (((class color) (min-colors 88) (background light))
     :background "#ffdddd")
    (((class color) (min-colors 88) (background dark))
     :background "#553333")
    (((class color))
     :foreground "red"))
  "`diff-mode' face used to highlight removed lines."
  :group 'diff-mode)

(defface diff-added
  '((default
     :inherit diff-changed)
    (((class color) (min-colors 88) (background light))
     :background "#ddffdd")
    (((class color) (min-colors 88) (background dark))
     :background "#335533")
    (((class color))
     :foreground "green"))
  "`diff-mode' face used to highlight added lines."
  :group 'diff-mode)

(defface diff-changed
  '((((class color) (min-colors 88) (background light))
     :background "grey90")
    (((class color) (min-colors 88) (background dark))
     :background "grey20")
    (((class color))
     :foreground "grey"))
  "`diff-mode' face used to highlight changed lines."
  :version "26.1"
  :group 'diff-mode)

(defface diff-indicator-removed
  '((t :inherit diff-removed))
  "`diff-mode' face used to highlight indicator of removed lines (-, <)."
  :group 'diff-mode
  :version "22.1")
(defvar diff-indicator-removed-face 'diff-indicator-removed)

(defface diff-indicator-added
  '((t :inherit diff-added))
  "`diff-mode' face used to highlight indicator of added lines (+, >)."
  :group 'diff-mode
  :version "22.1")
(defvar diff-indicator-added-face 'diff-indicator-added)

(defface diff-indicator-changed
  '((t :inherit diff-changed))
  "`diff-mode' face used to highlight indicator of changed lines."
  :group 'diff-mode
  :version "22.1")
(defvar diff-indicator-changed-face 'diff-indicator-changed)

(defface diff-function
  '((t :inherit diff-header))
  "`diff-mode' face used to highlight function names produced by \"diff -p\"."
  :group 'diff-mode)

(defface diff-context
  '((((class color grayscale) (min-colors 88) (background light))
     :foreground "#333333")
    (((class color grayscale) (min-colors 88) (background dark))
     :foreground "#dddddd"))
  "`diff-mode' face used to highlight context and other side-information."
  :version "25.1"
  :group 'diff-mode)

(defface diff-nonexistent
  '((t :inherit diff-file-header))
  "`diff-mode' face used to highlight nonexistent files in recursive diffs."
  :group 'diff-mode)

(defconst diff-yank-handler '(diff-yank-function))
(defun diff-yank-function (text)
  ;; FIXME: the yank-handler is now called separately on each piece of text
  ;; with a yank-handler property, so the next-single-property-change call
  ;; below will always return nil :-(   --stef
  (let ((mixed (next-single-property-change 0 'yank-handler text))
	(start (point)))
    ;; First insert the text.
    (insert text)
    ;; If the text does not include any diff markers and if we're not
    ;; yanking back into a diff-mode buffer, get rid of the prefixes.
    (unless (or mixed (derived-mode-p 'diff-mode))
      (undo-boundary)		; Just in case the user wanted the prefixes.
      (let ((re (save-excursion
		  (if (re-search-backward "^[><!][ \t]" start t)
		      (if (eq (char-after) ?!)
			  "^[!+- ][ \t]" "^[<>][ \t]")
		    "^[ <>!+-]"))))
	(save-excursion
	  (while (re-search-backward re start t)
	    (replace-match "" t t)))))))

(defconst diff-hunk-header-re-unified
  "^@@ -\\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? \\+\\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? @@")
(defconst diff-context-mid-hunk-header-re
  "--- \\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? ----$")

(defvar diff-use-changed-face (and (face-differs-from-default-p 'diff-changed)
				   (not (face-equal 'diff-changed 'diff-added))
				   (not (face-equal 'diff-changed 'diff-removed)))
  "If non-nil, use the face `diff-changed' for changed lines in context diffs.
Otherwise, use the face `diff-removed' for removed lines,
and the face `diff-added' for added lines.")

(defvar diff-font-lock-keywords
  `((,(concat "\\(" diff-hunk-header-re-unified "\\)\\(.*\\)$")
     (1 'diff-hunk-header) (6 'diff-function))
    ("^\\(\\*\\{15\\}\\)\\(.*\\)$"                        ;context
     (1 'diff-hunk-header) (2 'diff-function))
    ("^\\*\\*\\* .+ \\*\\*\\*\\*". 'diff-hunk-header) ;context
    (,diff-context-mid-hunk-header-re . 'diff-hunk-header) ;context
    ("^[0-9,]+[acd][0-9,]+$"     . 'diff-hunk-header) ;normal
    ("^---$"                     . 'diff-hunk-header) ;normal
    ;; For file headers, accept files with spaces, but be careful to rule
    ;; out false-positives when matching hunk headers.
    ("^\\(---\\|\\+\\+\\+\\|\\*\\*\\*\\) \\([^\t\n]+?\\)\\(?:\t.*\\| \\(\\*\\*\\*\\*\\|----\\)\\)?\n"
     (0 'diff-header)
     (2 (if (not (match-end 3)) 'diff-file-header) prepend))
    ("^\\([-<]\\)\\(.*\n\\)"
     (1 diff-indicator-removed-face) (2 'diff-removed))
    ("^\\([+>]\\)\\(.*\n\\)"
     (1 diff-indicator-added-face) (2 'diff-added))
    ("^\\(!\\)\\(.*\n\\)"
     (1 (if diff-use-changed-face
	    diff-indicator-changed-face
	  ;; Otherwise, search for `diff-context-mid-hunk-header-re' and
	  ;; if the line of context diff is above, use `diff-removed';
	  ;; if below, use `diff-added'.
	  (save-match-data
	    (let ((limit (save-excursion (diff-beginning-of-hunk))))
	      (if (save-excursion (re-search-backward diff-context-mid-hunk-header-re limit t))
		  diff-indicator-added-face
		diff-indicator-removed-face)))))
     (2 (if diff-use-changed-face
	    'diff-changed
	  ;; Otherwise, use the same method as above.
	  (save-match-data
	    (let ((limit (save-excursion (diff-beginning-of-hunk))))
	      (if (save-excursion (re-search-backward diff-context-mid-hunk-header-re limit t))
		  'diff-added
		'diff-removed))))))
    ("^\\(?:Index\\|revno\\): \\(.+\\).*\n"
     (0 'diff-header) (1 'diff-index prepend))
    ("^Only in .*\n" . 'diff-nonexistent)
    ("^\\(#\\)\\(.*\\)"
     (1 font-lock-comment-delimiter-face)
     (2 font-lock-comment-face))
    ("^[^-=+*!<>#].*\n" (0 'diff-context))))

(defconst diff-font-lock-defaults
  '(diff-font-lock-keywords t nil nil nil (font-lock-multiline . nil)))

(defvar diff-imenu-generic-expression
  ;; Prefer second name as first is most likely to be a backup or
  ;; version-control name.  The [\t\n] at the end of the unidiff pattern
  ;; catches Debian source diff files (which lack the trailing date).
  '((nil "\\+\\+\\+\\ \\([^\t\n]+\\)[\t\n]" 1) ; unidiffs
    (nil "^--- \\([^\t\n]+\\)\t.*\n\\*" 1))) ; context diffs

;;;;
;;;; Movement
;;;;

(defvar diff-valid-unified-empty-line t
  "If non-nil, empty lines are valid in unified diffs.
Some versions of diff replace all-blank context lines in unified format with
empty lines.  This makes the format less robust, but is tolerated.
See http://lists.gnu.org/archive/html/emacs-devel/2007-11/msg01990.html")

(defconst diff-hunk-header-re
  (concat "^\\(?:" diff-hunk-header-re-unified ".*\\|\\*\\{15\\}.*\n\\*\\*\\* .+ \\*\\*\\*\\*\\|[0-9]+\\(,[0-9]+\\)?[acd][0-9]+\\(,[0-9]+\\)?\\)$"))
(defconst diff-file-header-re (concat "^\\(--- .+\n\\+\\+\\+ \\|\\*\\*\\* .+\n--- \\|[^-+!<>0-9@* \n]\\).+\n" (substring diff-hunk-header-re 1)))

(defconst diff-separator-re "^--+ ?$")

(defvar diff-narrowed-to nil)

(defun diff-hunk-style (&optional style)
  (when (looking-at diff-hunk-header-re)
    (setq style (cdr (assq (char-after) '((?@ . unified) (?* . context)))))
    (goto-char (match-end 0)))
  style)

(defun diff-end-of-hunk (&optional style donttrustheader)
  "Advance to the end of the current hunk, and return its position."
  (let (end)
    (when (looking-at diff-hunk-header-re)
      ;; Especially important for unified (because headers are ambiguous).
      (setq style (diff-hunk-style style))
      (goto-char (match-end 0))
      (when (and (not donttrustheader) (match-end 2))
        (let* ((nold (string-to-number (or (match-string 2) "1")))
               (nnew (string-to-number (or (match-string 4) "1")))
               (endold
                (save-excursion
                  (re-search-forward (if diff-valid-unified-empty-line
                                         "^[- \n]" "^[- ]")
                                     nil t nold)
                  (line-beginning-position
                   ;; Skip potential "\ No newline at end of file".
                   (if (looking-at ".*\n\\\\") 3 2))))
               (endnew
                ;; The hunk may end with a bunch of "+" lines, so the `end' is
                ;; then further than computed above.
                (save-excursion
                  (re-search-forward (if diff-valid-unified-empty-line
                                         "^[+ \n]" "^[+ ]")
                                     nil t nnew)
                  (line-beginning-position
                   ;; Skip potential "\ No newline at end of file".
                   (if (looking-at ".*\n\\\\") 3 2)))))
          (setq end (max endold endnew)))))
    ;; We may have a first evaluation of `end' thanks to the hunk header.
    (unless end
      (setq end (and (re-search-forward
                      (pcase style
                        (`unified
                         (concat (if diff-valid-unified-empty-line
                                     "^[^-+# \\\n]\\|" "^[^-+# \\]\\|")
                                 ;; A `unified' header is ambiguous.
                                 diff-file-header-re))
                        (`context "^[^-+#! \\]")
                        (`normal "^[^<>#\\]")
                        (_ "^[^-+#!<> \\]"))
                      nil t)
                     (match-beginning 0)))
      (when diff-valid-unified-empty-line
        ;; While empty lines may be valid inside hunks, they are also likely
        ;; to be unrelated to the hunk.
        (goto-char (or end (point-max)))
        (while (eq ?\n (char-before (1- (point))))
          (forward-char -1)
          (setq end (point)))))
    ;; The return value is used by easy-mmode-define-navigation.
    (goto-char (or end (point-max)))))

;; "index ", "old mode", "new mode", "new file mode" and
;; "deleted file mode" are output by git-diff.
(defconst diff-file-junk-re
  (concat "Index: \\|Prereq: \\|=\\{20,\\}\\|" ; SVN
          "diff \\|index \\|\\(?:deleted file\\|new\\(?: file\\)?\\|old\\) mode\\|=== modified file"))

;; If point is in a diff header, then return beginning
;; of hunk position otherwise return nil.
(defun diff--at-diff-header-p ()
  "Return non-nil if point is inside a diff header."
  (let ((regexp-hunk diff-hunk-header-re)
        (regexp-file diff-file-header-re)
        (regexp-junk diff-file-junk-re)
        (orig (point)))
    (catch 'headerp
      (save-excursion
        (forward-line 0)
        (when (looking-at regexp-hunk) ; Hunk header.
          (throw 'headerp (point)))
        (forward-line -1)
        (when (re-search-forward regexp-file (point-at-eol 4) t) ; File header.
          (forward-line 0)
          (throw 'headerp (point)))
        (goto-char orig)
        (forward-line 0)
        (when (looking-at regexp-junk) ; Git diff junk.
          (while (and (looking-at regexp-junk)
                      (not (bobp)))
            (forward-line -1))
          (re-search-forward regexp-file nil t)
          (forward-line 0)
          (throw 'headerp (point)))) nil)))

(defun diff-beginning-of-hunk (&optional try-harder)
  "Move back to the previous hunk beginning, and return its position.
If point is in a file header rather than a hunk, advance to the
next hunk if TRY-HARDER is non-nil; otherwise signal an error."
  (beginning-of-line)
  (if (looking-at diff-hunk-header-re) ; At hunk header.
      (point)
    (let ((pos (diff--at-diff-header-p))
          (regexp diff-hunk-header-re))
      (cond (pos ; At junk diff header.
             (if try-harder
                 (goto-char pos)
               (error "Can't find the beginning of the hunk")))
            ((re-search-backward regexp nil t)) ; In the middle of a hunk.
            ((re-search-forward regexp nil t) ; At first hunk header.
             (forward-line 0)
             (point))
            (t (error "Can't find the beginning of the hunk"))))))

(defun diff-unified-hunk-p ()
  (save-excursion
    (ignore-errors
      (diff-beginning-of-hunk)
      (looking-at "^@@"))))

(defun diff-beginning-of-file ()
  (beginning-of-line)
  (unless (looking-at diff-file-header-re)
    (let ((start (point))
          res)
      ;; diff-file-header-re may need to match up to 4 lines, so in case
      ;; we're inside the header, we need to move up to 3 lines forward.
      (forward-line 3)
      (if (and (setq res (re-search-backward diff-file-header-re nil t))
               ;; Maybe the 3 lines forward were too much and we matched
               ;; a file header after our starting point :-(
               (or (<= (point) start)
                   (setq res (re-search-backward diff-file-header-re nil t))))
          res
        (goto-char start)
        (error "Can't find the beginning of the file")))))


(defun diff-end-of-file ()
  (re-search-forward "^[-+#!<>0-9@* \\]" nil t)
  (re-search-forward (concat "^[^-+#!<>0-9@* \\]\\|" diff-file-header-re)
		     nil 'move)
  (if (match-beginning 1)
      (goto-char (match-beginning 1))
    (beginning-of-line)))

(defvar diff--auto-refine-data nil)

;; Define diff-{hunk,file}-{prev,next}
(easy-mmode-define-navigation
 diff-hunk diff-hunk-header-re "hunk" diff-end-of-hunk diff-restrict-view
 (when diff-auto-refine-mode
   (unless (prog1 diff--auto-refine-data
             (setq diff--auto-refine-data
                   (cons (current-buffer) (point-marker))))
     (run-at-time 0.0 nil
                  (lambda ()
                    (when diff--auto-refine-data
                      (let ((buffer (car diff--auto-refine-data))
                            (point (cdr diff--auto-refine-data)))
                        (setq diff--auto-refine-data nil)
                        (with-local-quit
                          (when (buffer-live-p buffer)
                            (with-current-buffer buffer
                              (save-excursion
                                (goto-char point)
                                (diff-refine-hunk))))))))))))

(easy-mmode-define-navigation
 diff-file diff-file-header-re "file" diff-end-of-file)

(defun diff-bounds-of-hunk ()
  "Return the bounds of the diff hunk at point.
The return value is a list (BEG END), which are the hunk's start
and end positions.  Signal an error if no hunk is found.  If
point is in a file header, return the bounds of the next hunk."
  (save-excursion
    (let ((pos (point))
	  (beg (diff-beginning-of-hunk t))
	  (end (diff-end-of-hunk)))
      (cond ((>= end pos)
	     (list beg end))
	    ;; If this hunk ends above POS, consider the next hunk.
	    ((re-search-forward diff-hunk-header-re nil t)
	     (list (match-beginning 0) (diff-end-of-hunk)))
	    (t (error "No hunk found"))))))

(defun diff-bounds-of-file ()
  "Return the bounds of the file segment at point.
The return value is a list (BEG END), which are the segment's
start and end positions."
  (save-excursion
    (let ((pos (point))
	  (beg (progn (diff-beginning-of-file-and-junk)
		      (point))))
      (diff-end-of-file)
      ;; bzr puts a newline after the last hunk.
      (while (looking-at "^\n")
	(forward-char 1))
      (if (> pos (point))
	  (error "Not inside a file diff"))
      (list beg (point)))))

(defun diff-restrict-view (&optional arg)
  "Restrict the view to the current hunk.
If the prefix ARG is given, restrict the view to the current file instead."
  (interactive "P")
  (apply 'narrow-to-region
	 (if arg (diff-bounds-of-file) (diff-bounds-of-hunk)))
  (set (make-local-variable 'diff-narrowed-to) (if arg 'file 'hunk)))

(defun diff--some-hunks-p ()
  (save-excursion
    (goto-char (point-min))
    (re-search-forward diff-hunk-header-re nil t)))

(defun diff-hunk-kill ()
  "Kill the hunk at point."
  (interactive)
  (if (not (diff--some-hunks-p))
      (error "No hunks")
    (diff-beginning-of-hunk t)
    (let* ((hunk-bounds (diff-bounds-of-hunk))
           (file-bounds (ignore-errors (diff-bounds-of-file)))
           ;; If the current hunk is the only one for its file, kill the
           ;; file header too.
           (bounds (if (and file-bounds
                            (progn (goto-char (car file-bounds))
                                   (= (progn (diff-hunk-next) (point))
                                      (car hunk-bounds)))
                            (progn (goto-char (cadr hunk-bounds))
                                   ;; bzr puts a newline after the last hunk.
                                   (while (looking-at "^\n")
                                     (forward-char 1))
                                   (= (point) (cadr file-bounds))))
                       file-bounds
                     hunk-bounds))
           (inhibit-read-only t))
      (apply 'kill-region bounds)
      (goto-char (car bounds))
      (ignore-errors (diff-beginning-of-hunk t)))))

(defun diff-beginning-of-file-and-junk ()
  "Go to the beginning of file-related diff-info.
This is like `diff-beginning-of-file' except it tries to skip back over leading
data such as \"Index: ...\" and such."
  (let* ((orig (point))
         ;; Skip forward over what might be "leading junk" so as to get
         ;; closer to the actual diff.
         (_ (progn (beginning-of-line)
                   (while (looking-at diff-file-junk-re)
                     (forward-line 1))))
         (start (point))
         (prevfile (condition-case err
                       (save-excursion (diff-beginning-of-file) (point))
                     (error err)))
         (err (if (consp prevfile) prevfile))
         (nextfile (ignore-errors
                     (save-excursion
                       (goto-char start) (diff-file-next) (point))))
         ;; prevhunk is one of the limits.
         (prevhunk (save-excursion
                     (ignore-errors
                       (if (numberp prevfile) (goto-char prevfile))
                       (diff-hunk-prev) (point))))
         (previndex (save-excursion
                      (forward-line 1)  ;In case we're looking at "Index:".
                      (re-search-backward "^Index: " prevhunk t))))
    ;; If we're in the junk, we should use nextfile instead of prevfile.
    (if (and (numberp nextfile)
             (or (not (numberp prevfile))
                 (and previndex (> previndex prevfile))))
        (setq prevfile nextfile))
    (if (and previndex (numberp prevfile) (< previndex prevfile))
        (setq prevfile previndex))
    (if (and (numberp prevfile) (<= prevfile start))
          (progn
            (goto-char prevfile)
            ;; Now skip backward over the leading junk we may have before the
            ;; diff itself.
            (while (save-excursion
                     (and (zerop (forward-line -1))
                          (looking-at diff-file-junk-re)))
              (forward-line -1)))
      ;; File starts *after* the starting point: we really weren't in
      ;; a file diff but elsewhere.
      (goto-char orig)
      (signal (car err) (cdr err)))))

(defun diff-file-kill ()
  "Kill current file's hunks."
  (interactive)
  (if (not (diff--some-hunks-p))
      (error "No hunks")
    (diff-beginning-of-hunk t)
    (let ((inhibit-read-only t))
      (apply 'kill-region (diff-bounds-of-file)))
    (ignore-errors (diff-beginning-of-hunk t))))

(defun diff-kill-junk ()
  "Kill spurious empty diffs."
  (interactive)
  (save-excursion
    (let ((inhibit-read-only t))
      (goto-char (point-min))
      (while (re-search-forward (concat "^\\(Index: .*\n\\)"
					"\\([^-+!* <>].*\n\\)*?"
					"\\(\\(Index:\\) \\|"
					diff-file-header-re "\\)")
				nil t)
	(delete-region (if (match-end 4) (match-beginning 0) (match-end 1))
		       (match-beginning 3))
	(beginning-of-line)))))

(defun diff-count-matches (re start end)
  (save-excursion
    (let ((n 0))
      (goto-char start)
      (while (re-search-forward re end t) (cl-incf n))
      n)))

(defun diff-splittable-p ()
  (save-excursion
    (beginning-of-line)
    (and (looking-at "^[-+ ]")
         (progn (forward-line -1) (looking-at "^[-+ ]"))
         (diff-unified-hunk-p))))

(defun diff-split-hunk ()
  "Split the current (unified diff) hunk at point into two hunks."
  (interactive)
  (beginning-of-line)
  (let ((pos (point))
	(start (diff-beginning-of-hunk)))
    (unless (looking-at diff-hunk-header-re-unified)
      (error "diff-split-hunk only works on unified context diffs"))
    (forward-line 1)
    (let* ((start1 (string-to-number (match-string 1)))
	   (start2 (string-to-number (match-string 3)))
	   (newstart1 (+ start1 (diff-count-matches "^[- \t]" (point) pos)))
	   (newstart2 (+ start2 (diff-count-matches "^[+ \t]" (point) pos)))
	   (inhibit-read-only t))
      (goto-char pos)
      ;; Hopefully the after-change-function will not screw us over.
      (insert "@@ -" (number-to-string newstart1) ",1 +"
	      (number-to-string newstart2) ",1 @@\n")
      ;; Fix the original hunk-header.
      (diff-fixup-modifs start pos))))


;;;;
;;;; jump to other buffers
;;;;

(defvar diff-remembered-files-alist nil)
(defvar diff-remembered-defdir nil)

(defun diff-filename-drop-dir (file)
  (when (string-match "/" file) (substring file (match-end 0))))

(defun diff-merge-strings (ancestor from to)
  "Merge the diff between ANCESTOR and FROM into TO.
Returns the merged string if successful or nil otherwise.
The strings are assumed not to contain any \"\\n\" (i.e. end of line).
If ANCESTOR = FROM, returns TO.
If ANCESTOR = TO, returns FROM.
The heuristic is simplistic and only really works for cases
like \(diff-merge-strings \"b/foo\" \"b/bar\" \"/a/c/foo\")."
  ;; Ideally, we want:
  ;;   AMB ANB CMD -> CND
  ;; but that's ambiguous if `foo' or `bar' is empty:
  ;; a/foo a/foo1 b/foo.c -> b/foo1.c but not 1b/foo.c or b/foo.c1
  (let ((str (concat ancestor "\n" from "\n" to)))
    (when (and (string-match (concat
			      "\\`\\(.*?\\)\\(.*\\)\\(.*\\)\n"
			      "\\1\\(.*\\)\\3\n"
			      "\\(.*\\(\\2\\).*\\)\\'") str)
	       (equal to (match-string 5 str)))
      (concat (substring str (match-beginning 5) (match-beginning 6))
	      (match-string 4 str)
	      (substring str (match-end 6) (match-end 5))))))

(defun diff-tell-file-name (old name)
  "Tell Emacs where the find the source file of the current hunk.
If the OLD prefix arg is passed, tell the file NAME of the old file."
  (interactive
   (let* ((old current-prefix-arg)
	  (fs (diff-hunk-file-names current-prefix-arg)))
     (unless fs (error "No file name to look for"))
     (list old (read-file-name (format "File for %s: " (car fs))
			       nil (diff-find-file-name old 'noprompt) t))))
  (let ((fs (diff-hunk-file-names old)))
    (unless fs (error "No file name to look for"))
    (push (cons fs name) diff-remembered-files-alist)))

(defun diff-hunk-file-names (&optional old)
  "Give the list of file names textually mentioned for the current hunk."
  (save-excursion
    (unless (looking-at diff-file-header-re)
      (or (ignore-errors (diff-beginning-of-file))
	  (re-search-forward diff-file-header-re nil t)))
    (let ((limit (save-excursion
		   (condition-case ()
		       (progn (diff-hunk-prev) (point))
		     (error (point-min)))))
	  (header-files
           ;; handle filenames with spaces;
           ;; cf. diff-font-lock-keywords / diff-file-header
	   (if (looking-at "[-*][-*][-*] \\([^\t\n]+\\).*\n[-+][-+][-+] \\([^\t\n]+\\)")
	       (list (if old (match-string 1) (match-string 2))
		     (if old (match-string 2) (match-string 1)))
	     (forward-line 1) nil)))
      (delq nil
	    (append
	     (when (and (not old)
			(save-excursion
			  (re-search-backward "^Index: \\(.+\\)" limit t)))
	       (list (match-string 1)))
	     header-files
             ;; this assumes that there are no spaces in filenames
	     (when (re-search-backward
		    "^diff \\(-\\S-+ +\\)*\\(\\S-+\\)\\( +\\(\\S-+\\)\\)?"
		    nil t)
	       (list (if old (match-string 2) (match-string 4))
		     (if old (match-string 4) (match-string 2)))))))))

(defun diff-find-file-name (&optional old noprompt prefix)
  "Return the file corresponding to the current patch.
Non-nil OLD means that we want the old file.
Non-nil NOPROMPT means to prefer returning nil than to prompt the user.
PREFIX is only used internally: don't use it."
  (unless (equal diff-remembered-defdir default-directory)
    ;; Flush diff-remembered-files-alist if the default-directory is changed.
    (set (make-local-variable 'diff-remembered-defdir) default-directory)
    (set (make-local-variable 'diff-remembered-files-alist) nil))
  (save-excursion
    (unless (looking-at diff-file-header-re)
      (or (ignore-errors (diff-beginning-of-file))
	  (re-search-forward diff-file-header-re nil t)))
    (let ((fs (diff-hunk-file-names old)))
      (if prefix (setq fs (mapcar (lambda (f) (concat prefix f)) fs)))
      (or
       ;; use any previously used preference
       (cdr (assoc fs diff-remembered-files-alist))
       ;; try to be clever and use previous choices as an inspiration
       (cl-dolist (rf diff-remembered-files-alist)
	 (let ((newfile (diff-merge-strings (caar rf) (car fs) (cdr rf))))
	   (if (and newfile (file-exists-p newfile)) (cl-return newfile))))
       ;; look for each file in turn.  If none found, try again but
       ;; ignoring the first level of directory, ...
       (cl-do* ((files fs (delq nil (mapcar 'diff-filename-drop-dir files)))
                (file nil nil))
	   ((or (null files)
		(setq file (cl-do* ((files files (cdr files))
                                    (file (car files) (car files)))
			       ;; Use file-regular-p to avoid
			       ;; /dev/null, directories, etc.
			       ((or (null file) (file-regular-p file))
				file))))
	    file))
       ;; <foo>.rej patches implicitly apply to <foo>
       (and (string-match "\\.rej\\'" (or buffer-file-name ""))
	    (let ((file (substring buffer-file-name 0 (match-beginning 0))))
	      (when (file-exists-p file) file)))
       ;; If we haven't found the file, maybe it's because we haven't paid
       ;; attention to the PCL-CVS hint.
       (and (not prefix)
	    (boundp 'cvs-pcl-cvs-dirchange-re)
	    (save-excursion
	      (re-search-backward cvs-pcl-cvs-dirchange-re nil t))
	    (diff-find-file-name old noprompt (match-string 1)))
       ;; if all else fails, ask the user
       (unless noprompt
         (let ((file (expand-file-name (or (car fs) ""))))
	   (setq file
		 (read-file-name (format "Use file %s: " file)
				 (file-name-directory file) file t
				 (file-name-nondirectory file)))
           (set (make-local-variable 'diff-remembered-files-alist)
                (cons (cons fs file) diff-remembered-files-alist))
           file))))))


(defun diff-ediff-patch ()
  "Call `ediff-patch-file' on the current buffer."
  (interactive)
  (condition-case nil
      (ediff-patch-file nil (current-buffer))
    (wrong-number-of-arguments (ediff-patch-file))))

;;;;
;;;; Conversion functions
;;;;

;;(defvar diff-inhibit-after-change nil
;;  "Non-nil means inhibit `diff-mode's after-change functions.")

(defun diff-unified->context (start end)
  "Convert unified diffs to context diffs.
START and END are either taken from the region (if a prefix arg is given) or
else cover the whole buffer."
  (interactive (if (or current-prefix-arg (use-region-p))
		   (list (region-beginning) (region-end))
		 (list (point-min) (point-max))))
  (unless (markerp end) (setq end (copy-marker end t)))
  (let (;;(diff-inhibit-after-change t)
	(inhibit-read-only t))
    (save-excursion
      (goto-char start)
      (while (and (re-search-forward
                   (concat "^\\(\\(---\\) .+\n\\(\\+\\+\\+\\) .+\\|"
                           diff-hunk-header-re-unified ".*\\)$")
                   nil t)
		  (< (point) end))
	(combine-after-change-calls
	  (if (match-beginning 2)
	      ;; we matched a file header
	      (progn
		;; use reverse order to make sure the indices are kept valid
		(replace-match "---" t t nil 3)
		(replace-match "***" t t nil 2))
	    ;; we matched a hunk header
	    (let ((line1 (match-string 4))
		  (lines1 (or (match-string 5) "1"))
		  (line2 (match-string 6))
		  (lines2 (or (match-string 7) "1"))
		  ;; Variables to use the special undo function.
		  (old-undo buffer-undo-list)
		  (old-end (marker-position end))
		  (start (match-beginning 0))
		  (reversible t))
	      (replace-match
	       (concat "***************\n*** " line1 ","
		       (number-to-string (+ (string-to-number line1)
					    (string-to-number lines1)
					    -1))
		       " ****"))
	      (save-restriction
		(narrow-to-region (line-beginning-position 2)
                                  ;; Call diff-end-of-hunk from just before
                                  ;; the hunk header so it can use the hunk
                                  ;; header info.
				  (progn (diff-end-of-hunk 'unified) (point)))
		(let ((hunk (buffer-string)))
		  (goto-char (point-min))
		  (if (not (save-excursion (re-search-forward "^-" nil t)))
		      (delete-region (point) (point-max))
		    (goto-char (point-max))
		    (let ((modif nil) last-pt)
		      (while (progn (setq last-pt (point))
				    (= (forward-line -1) 0))
			(pcase (char-after)
			  (?\s (insert " ") (setq modif nil) (backward-char 1))
			  (?+ (delete-region (point) last-pt) (setq modif t))
			  (?- (if (not modif)
                                  (progn (forward-char 1)
                                         (insert " "))
                                (delete-char 1)
                                (insert "! "))
                              (backward-char 2))
			  (?\\ (when (save-excursion (forward-line -1)
                                                     (= (char-after) ?+))
                                 (delete-region (point) last-pt)
                                 (setq modif t)))
                          ;; diff-valid-unified-empty-line.
                          (?\n (insert "  ") (setq modif nil)
                               (backward-char 2))
			  (_ (setq modif nil))))))
		  (goto-char (point-max))
		  (save-excursion
		    (insert "--- " line2 ","
			    (number-to-string (+ (string-to-number line2)
						 (string-to-number lines2)
						 -1))
                            " ----\n" hunk))
		  ;;(goto-char (point-min))
		  (forward-line 1)
		  (if (not (save-excursion (re-search-forward "^+" nil t)))
		      (delete-region (point) (point-max))
		    (let ((modif nil) (delete nil))
		      (if (save-excursion (re-search-forward "^\\+.*\n-"
                                                             nil t))
                          ;; Normally, lines in a substitution come with
                          ;; first the removals and then the additions, and
                          ;; the context->unified function follows this
                          ;; convention, of course.  Yet, other alternatives
                          ;; are valid as well, but they preclude the use of
                          ;; context->unified as an undo command.
			  (setq reversible nil))
		      (while (not (eobp))
			(pcase (char-after)
			  (?\s (insert " ") (setq modif nil) (backward-char 1))
			  (?- (setq delete t) (setq modif t))
			  (?+ (if (not modif)
                                  (progn (forward-char 1)
                                         (insert " "))
                                (delete-char 1)
                                (insert "! "))
                              (backward-char 2))
			  (?\\ (when (save-excursion (forward-line 1)
                                                     (not (eobp)))
                                 (setq delete t) (setq modif t)))
                          ;; diff-valid-unified-empty-line.
                          (?\n (insert "  ") (setq modif nil) (backward-char 2)
                               (setq reversible nil))
			  (_ (setq modif nil)))
			(let ((last-pt (point)))
			  (forward-line 1)
			  (when delete
			    (delete-region last-pt (point))
			    (setq delete nil)))))))
		(unless (or (not reversible) (eq buffer-undo-list t))
                  ;; Drop the many undo entries and replace them with
                  ;; a single entry that uses diff-context->unified to do
                  ;; the work.
		  (setq buffer-undo-list
			(cons (list 'apply (- old-end end) start (point-max)
				    'diff-context->unified start (point-max))
			      old-undo)))))))))))

(defun diff-context->unified (start end &optional to-context)
  "Convert context diffs to unified diffs.
START and END are either taken from the region
\(when it is highlighted) or else cover the whole buffer.
With a prefix argument, convert unified format to context format."
  (interactive (if (use-region-p)
		   (list (region-beginning) (region-end) current-prefix-arg)
		 (list (point-min) (point-max) current-prefix-arg)))
  (if to-context
      (diff-unified->context start end)
    (unless (markerp end) (setq end (copy-marker end t)))
    (let ( ;;(diff-inhibit-after-change t)
          (inhibit-read-only t))
      (save-excursion
        (goto-char start)
        (while (and (re-search-forward "^\\(\\(\\*\\*\\*\\) .+\n\\(---\\) .+\\|\\*\\{15\\}.*\n\\*\\*\\* \\([0-9]+\\),\\(-?[0-9]+\\) \\*\\*\\*\\*\\)\\(?: \\(.*\\)\\|$\\)" nil t)
                    (< (point) end))
          (combine-after-change-calls
            (if (match-beginning 2)
                ;; we matched a file header
                (progn
                  ;; use reverse order to make sure the indices are kept valid
                  (replace-match "+++" t t nil 3)
                  (replace-match "---" t t nil 2))
              ;; we matched a hunk header
              (let ((line1s (match-string 4))
                    (line1e (match-string 5))
                    (pt1 (match-beginning 0))
                    ;; Variables to use the special undo function.
                    (old-undo buffer-undo-list)
                    (old-end (marker-position end))
                    ;; We currently throw away the comment that can follow
                    ;; the hunk header.  FIXME: Preserve it instead!
                    (reversible (not (match-end 6))))
                (replace-match "")
                (unless (re-search-forward
                         diff-context-mid-hunk-header-re nil t)
                  (error "Can't find matching `--- n1,n2 ----' line"))
                (let ((line2s (match-string 1))
                      (line2e (match-string 2))
                      (pt2 (progn
                             (delete-region (progn (beginning-of-line) (point))
                                            (progn (forward-line 1) (point)))
                             (point-marker))))
                  (goto-char pt1)
                  (forward-line 1)
                  (while (< (point) pt2)
                    (pcase (char-after)
                      (?! (delete-char 2) (insert "-") (forward-line 1))
                      (?- (forward-char 1) (delete-char 1) (forward-line 1))
                      (?\s              ;merge with the other half of the chunk
                       (let* ((endline2
                               (save-excursion
                                 (goto-char pt2) (forward-line 1) (point))))
                         (pcase (char-after pt2)
                           ((or ?! ?+)
                            (insert "+"
                                    (prog1
                                        (buffer-substring (+ pt2 2) endline2)
                                      (delete-region pt2 endline2))))
                           (?\s
                            (unless (= (- endline2 pt2)
                                       (- (line-beginning-position 2) (point)))
                              ;; If the two lines we're merging don't have the
                              ;; same length (can happen with "diff -b"), then
                              ;; diff-unified->context will not properly undo
                              ;; this operation.
                              (setq reversible nil))
                            (delete-region pt2 endline2)
                            (delete-char 1)
                            (forward-line 1))
                           (?\\ (forward-line 1))
                           (_ (setq reversible nil)
                              (delete-char 1) (forward-line 1)))))
                      (_ (setq reversible nil) (forward-line 1))))
                  (while (looking-at "[+! ] ")
                    (if (/= (char-after) ?!) (forward-char 1)
                      (delete-char 1) (insert "+"))
                    (delete-char 1) (forward-line 1))
                  (save-excursion
                    (goto-char pt1)
                    (insert "@@ -" line1s ","
                            (number-to-string (- (string-to-number line1e)
                                                 (string-to-number line1s)
                                                 -1))
                            " +" line2s ","
                            (number-to-string (- (string-to-number line2e)
                                                 (string-to-number line2s)
                                                 -1)) " @@"))
                  (set-marker pt2 nil)
                  ;; The whole procedure succeeded, let's replace the myriad
                  ;; of undo elements with just a single special one.
                  (unless (or (not reversible) (eq buffer-undo-list t))
                    (setq buffer-undo-list
                          (cons (list 'apply (- old-end end) pt1 (point)
                                      'diff-unified->context pt1 (point))
                                old-undo)))
                  )))))))))

(defun diff-reverse-direction (start end)
  "Reverse the direction of the diffs.
START and END are either taken from the region (if a prefix arg is given) or
else cover the whole buffer."
  (interactive (if (or current-prefix-arg (use-region-p))
		   (list (region-beginning) (region-end))
		 (list (point-min) (point-max))))
  (unless (markerp end) (setq end (copy-marker end t)))
  (let (;;(diff-inhibit-after-change t)
	(inhibit-read-only t))
    (save-excursion
      (goto-char start)
      (while (and (re-search-forward "^\\(\\([-*][-*][-*] \\)\\(.+\\)\n\\([-+][-+][-+] \\)\\(.+\\)\\|\\*\\{15\\}.*\n\\*\\*\\* \\(.+\\) \\*\\*\\*\\*\\|@@ -\\([0-9,]+\\) \\+\\([0-9,]+\\) @@.*\\)$" nil t)
		  (< (point) end))
	(combine-after-change-calls
	  (cond
	   ;; a file header
	   ((match-beginning 2) (replace-match "\\2\\5\n\\4\\3" nil))
	   ;; a context-diff hunk header
	   ((match-beginning 6)
	    (let ((pt-lines1 (match-beginning 6))
		  (lines1 (match-string 6)))
	      (replace-match "" nil nil nil 6)
	      (forward-line 1)
	      (let ((half1s (point)))
		(while (looking-at "[-! \\][ \t]\\|#")
		  (when (= (char-after) ?-) (delete-char 1) (insert "+"))
		  (forward-line 1))
		(let ((half1 (delete-and-extract-region half1s (point))))
		  (unless (looking-at diff-context-mid-hunk-header-re)
		    (insert half1)
		    (error "Can't find matching `--- n1,n2 ----' line"))
		  (let* ((str1end (or (match-end 2) (match-end 1)))
                         (str1 (buffer-substring (match-beginning 1) str1end)))
                    (goto-char str1end)
                    (insert lines1)
                    (delete-region (match-beginning 1) str1end)
		    (forward-line 1)
		    (let ((half2s (point)))
		      (while (looking-at "[!+ \\][ \t]\\|#")
			(when (= (char-after) ?+) (delete-char 1) (insert "-"))
			(forward-line 1))
		      (let ((half2 (delete-and-extract-region half2s (point))))
			(insert (or half1 ""))
			(goto-char half1s)
			(insert (or half2 ""))))
		    (goto-char pt-lines1)
		    (insert str1))))))
	   ;; a unified-diff hunk header
	   ((match-beginning 7)
	    (replace-match "@@ -\\8 +\\7 @@" nil)
	    (forward-line 1)
	    (let ((c (char-after)) first last)
	      (while (pcase (setq c (char-after))
		       (?- (setq first (or first (point)))
                           (delete-char 1) (insert "+") t)
		       (?+ (setq last (or last (point)))
                           (delete-char 1) (insert "-") t)
		       ((or ?\\ ?#) t)
		       (_ (when (and first last (< first last))
			    (insert (delete-and-extract-region first last)))
			  (setq first nil last nil)
			  (memq c (if diff-valid-unified-empty-line
                                      '(?\s ?\n) '(?\s)))))
		(forward-line 1))))))))))

(defun diff-fixup-modifs (start end)
  "Fixup the hunk headers (in case the buffer was modified).
START and END are either taken from the region (if a prefix arg is given) or
else cover the whole buffer."
  (interactive (if (or current-prefix-arg (use-region-p))
		   (list (region-beginning) (region-end))
		 (list (point-min) (point-max))))
  (let ((inhibit-read-only t))
    (save-excursion
      (goto-char end) (diff-end-of-hunk nil 'donttrustheader)
      (let ((plus 0) (minus 0) (space 0) (bang 0))
	(while (and (= (forward-line -1) 0) (<= start (point)))
	  (if (not (looking-at
		    (concat diff-hunk-header-re-unified
			    "\\|[-*][-*][-*] [0-9,]+ [-*][-*][-*][-*]$"
			    "\\|--- .+\n\\+\\+\\+ ")))
	      (pcase (char-after)
		(?\s (cl-incf space))
		(?+ (cl-incf plus))
		(?- (cl-incf minus))
		(?! (cl-incf bang))
		((or ?\\ ?#) nil)
		(?\n (if diff-valid-unified-empty-line
			 (cl-incf space)
		       (setq space 0 plus 0 minus 0 bang 0)))
		(_  (setq space 0 plus 0 minus 0 bang 0)))
	    (cond
	     ((looking-at diff-hunk-header-re-unified)
	      (let* ((old1 (match-string 2))
		     (old2 (match-string 4))
		     (new1 (number-to-string (+ space minus)))
		     (new2 (number-to-string (+ space plus))))
		(if old2
		    (unless (string= new2 old2) (replace-match new2 t t nil 4))
		  (goto-char (match-end 3))
		  (insert "," new2))
		(if old1
		    (unless (string= new1 old1) (replace-match new1 t t nil 2))
		  (goto-char (match-end 1))
		  (insert "," new1))))
	     ((looking-at diff-context-mid-hunk-header-re)
	      (when (> (+ space bang plus) 0)
		(let* ((old1 (match-string 1))
		       (old2 (match-string 2))
		       (new (number-to-string
			     (+ space bang plus -1 (string-to-number old1)))))
		  (unless (string= new old2) (replace-match new t t nil 2)))))
	     ((looking-at "\\*\\*\\* \\([0-9]+\\),\\(-?[0-9]*\\) \\*\\*\\*\\*$")
	      (when (> (+ space bang minus) 0)
		(let* ((old (match-string 1))
		       (new (format
			     (concat "%0" (number-to-string (length old)) "d")
			     (+ space bang minus -1 (string-to-number old)))))
		  (unless (string= new old) (replace-match new t t nil 2))))))
	    (setq space 0 plus 0 minus 0 bang 0)))))))

;;;;
;;;; Hooks
;;;;

(defun diff-write-contents-hooks ()
  "Fixup hunk headers if necessary."
  (if (buffer-modified-p) (diff-fixup-modifs (point-min) (point-max)))
  nil)

;; It turns out that making changes in the buffer from within an
;; *-change-function is asking for trouble, whereas making them
;; from a post-command-hook doesn't pose much problems
(defvar diff-unhandled-changes nil)
(defun diff-after-change-function (beg end _len)
  "Remember to fixup the hunk header.
See `after-change-functions' for the meaning of BEG, END and LEN."
  ;; Ignoring changes when inhibit-read-only is set is strictly speaking
  ;; incorrect, but it turns out that inhibit-read-only is normally not set
  ;; inside editing commands, while it tends to be set when the buffer gets
  ;; updated by an async process or by a conversion function, both of which
  ;; would rather not be uselessly slowed down by this hook.
  (when (and (not undo-in-progress) (not inhibit-read-only))
    (if diff-unhandled-changes
	(setq diff-unhandled-changes
	      (cons (min beg (car diff-unhandled-changes))
		    (max end (cdr diff-unhandled-changes))))
      (setq diff-unhandled-changes (cons beg end)))))

(defun diff-post-command-hook ()
  "Fixup hunk headers if necessary."
  (when (consp diff-unhandled-changes)
    (ignore-errors
      (save-excursion
	(goto-char (car diff-unhandled-changes))
	;; Maybe we've cut the end of the hunk before point.
	(if (and (bolp) (not (bobp))) (backward-char 1))
	;; We used to fixup modifs on all the changes, but it turns out that
	;; it's safer not to do it on big changes, e.g. when yanking a big
	;; diff, or when the user edits the header, since we might then
	;; screw up perfectly correct values.  --Stef
	(diff-beginning-of-hunk t)
        (let* ((style (if (looking-at "\\*\\*\\*") 'context))
               (start (line-beginning-position (if (eq style 'context) 3 2)))
               (mid (if (eq style 'context)
                        (save-excursion
                          (re-search-forward diff-context-mid-hunk-header-re
                                             nil t)))))
          (when (and ;; Don't try to fixup changes in the hunk header.
                 (>= (car diff-unhandled-changes) start)
                 ;; Don't try to fixup changes in the mid-hunk header either.
                 (or (not mid)
                     (< (cdr diff-unhandled-changes) (match-beginning 0))
                     (> (car diff-unhandled-changes) (match-end 0)))
                 (save-excursion
		(diff-end-of-hunk nil 'donttrustheader)
                   ;; Don't try to fixup changes past the end of the hunk.
                   (>= (point) (cdr diff-unhandled-changes))))
	  (diff-fixup-modifs (point) (cdr diff-unhandled-changes)))))
      (setq diff-unhandled-changes nil))))

(defun diff-next-error (arg reset)
  ;; Select a window that displays the current buffer so that point
  ;; movements are reflected in that window.  Otherwise, the user might
  ;; never see the hunk corresponding to the source she's jumping to.
  (pop-to-buffer (current-buffer))
  (if reset (goto-char (point-min)))
  (diff-hunk-next arg)
  (diff-goto-source))

(defvar whitespace-style)
(defvar whitespace-trailing-regexp)

;;;###autoload
(define-derived-mode diff-mode fundamental-mode "Diff"
  "Major mode for viewing/editing context diffs.
Supports unified and context diffs as well as (to a lesser extent)
normal diffs.

When the buffer is read-only, the ESC prefix is not necessary.
If you edit the buffer manually, diff-mode will try to update the hunk
headers for you on-the-fly.

You can also switch between context diff and unified diff with \\[diff-context->unified],
or vice versa with \\[diff-unified->context] and you can also reverse the direction of
a diff with \\[diff-reverse-direction].

   \\{diff-mode-map}"

  (set (make-local-variable 'font-lock-defaults) diff-font-lock-defaults)
  (add-hook 'font-lock-mode-hook
            (lambda () (remove-overlays nil nil 'diff-mode 'fine))
            nil 'local)
  (set (make-local-variable 'outline-regexp) diff-outline-regexp)
  (set (make-local-variable 'imenu-generic-expression)
       diff-imenu-generic-expression)
  ;; These are not perfect.  They would be better done separately for
  ;; context diffs and unidiffs.
  ;; (set (make-local-variable 'paragraph-start)
  ;;        (concat "@@ "			; unidiff hunk
  ;; 	       "\\|\\*\\*\\* "		; context diff hunk or file start
  ;; 	       "\\|--- [^\t]+\t"))	; context or unidiff file
  ;; 					; start (first or second line)
  ;;   (set (make-local-variable 'paragraph-separate) paragraph-start)
  ;;   (set (make-local-variable 'page-delimiter) "--- [^\t]+\t")
  ;; compile support
  (set (make-local-variable 'next-error-function) 'diff-next-error)

  (set (make-local-variable 'beginning-of-defun-function)
       'diff-beginning-of-file-and-junk)
  (set (make-local-variable 'end-of-defun-function)
       'diff-end-of-file)

  (diff-setup-whitespace)

  (if diff-default-read-only
      (setq buffer-read-only t))
  ;; setup change hooks
  (if (not diff-update-on-the-fly)
      (add-hook 'write-contents-functions 'diff-write-contents-hooks nil t)
    (make-local-variable 'diff-unhandled-changes)
    (add-hook 'after-change-functions 'diff-after-change-function nil t)
    (add-hook 'post-command-hook 'diff-post-command-hook nil t))
  ;; Neat trick from Dave Love to add more bindings in read-only mode:
  (let ((ro-bind (cons 'buffer-read-only diff-mode-shared-map)))
    (add-to-list 'minor-mode-overriding-map-alist ro-bind)
    ;; Turn off this little trick in case the buffer is put in view-mode.
    (add-hook 'view-mode-hook
	      (lambda ()
		(setq minor-mode-overriding-map-alist
		      (delq ro-bind minor-mode-overriding-map-alist)))
	      nil t))
  ;; add-log support
  (set (make-local-variable 'add-log-current-defun-function)
       'diff-current-defun)
  (set (make-local-variable 'add-log-buffer-file-name-function)
       (lambda () (diff-find-file-name nil 'noprompt)))
  (unless (buffer-file-name)
    (hack-dir-local-variables-non-file-buffer)))

;;;###autoload
(define-minor-mode diff-minor-mode
  "Toggle Diff minor mode.
With a prefix argument ARG, enable Diff minor mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
the mode if ARG is omitted or nil.

\\{diff-minor-mode-map}"
  :group 'diff-mode :lighter " Diff"
  ;; FIXME: setup font-lock
  ;; setup change hooks
  (if (not diff-update-on-the-fly)
      (add-hook 'write-contents-functions 'diff-write-contents-hooks nil t)
    (make-local-variable 'diff-unhandled-changes)
    (add-hook 'after-change-functions 'diff-after-change-function nil t)
    (add-hook 'post-command-hook 'diff-post-command-hook nil t)))

;;; Handy hook functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun diff-setup-whitespace ()
  "Set up Whitespace mode variables for the current Diff mode buffer.
This sets `whitespace-style' and `whitespace-trailing-regexp' so
that Whitespace mode shows trailing whitespace problems on the
modified lines of the diff."
  (set (make-local-variable 'whitespace-style) '(face trailing))
  (let ((style (save-excursion
		 (goto-char (point-min))
                 ;; FIXME: For buffers filled from async processes, this search
                 ;; will simply fail because the buffer is still empty :-(
		 (when (re-search-forward diff-hunk-header-re nil t)
		   (goto-char (match-beginning 0))
		   (diff-hunk-style)))))
    (set (make-local-variable 'whitespace-trailing-regexp)
	 (if (eq style 'context)
	     "^[-+!] .*?\\([\t ]+\\)$"
	   "^[-+!<>].*?\\([\t ]+\\)$"))))

(defun diff-delete-if-empty ()
  ;; An empty diff file means there's no more diffs to integrate, so we
  ;; can just remove the file altogether.  Very handy for .rej files if we
  ;; remove hunks as we apply them.
  (when (and buffer-file-name
	     (eq 0 (nth 7 (file-attributes buffer-file-name))))
    (delete-file buffer-file-name)))

(defun diff-delete-empty-files ()
  "Arrange for empty diff files to be removed."
  (add-hook 'after-save-hook 'diff-delete-if-empty nil t))

(defun diff-make-unified ()
  "Turn context diffs into unified diffs if applicable."
  (if (save-excursion
	(goto-char (point-min))
	(and (looking-at diff-hunk-header-re) (eq (char-after) ?*)))
      (let ((mod (buffer-modified-p)))
	(unwind-protect
	    (diff-context->unified (point-min) (point-max))
	  (restore-buffer-modified-p mod)))))

;;;
;;; Misc operations that have proved useful at some point.
;;;

(defun diff-next-complex-hunk ()
  "Jump to the next \"complex\" hunk.
\"Complex\" is approximated by \"the hunk changes the number of lines\".
Only works for unified diffs."
  (interactive)
  (while
      (and (re-search-forward diff-hunk-header-re-unified nil t)
	   (equal (match-string 2) (match-string 4)))))

(defun diff-sanity-check-context-hunk-half (lines)
  (let ((count lines))
    (while
        (cond
         ((and (memq (char-after) '(?\s ?! ?+ ?-))
               (memq (char-after (1+ (point))) '(?\s ?\t)))
          (cl-decf count) t)
         ((or (zerop count) (= count lines)) nil)
         ((memq (char-after) '(?! ?+ ?-))
          (if (not (and (eq (char-after (1+ (point))) ?\n)
                        (y-or-n-p "Try to auto-fix whitespace loss damage? ")))
              (error "End of hunk ambiguously marked")
            (forward-char 1) (insert " ") (forward-line -1) t))
         ((< lines 0)
          (error "End of hunk ambiguously marked"))
         ((not (y-or-n-p "Try to auto-fix whitespace loss and word-wrap damage? "))
          (error "Abort!"))
         ((eolp) (insert "  ") (forward-line -1) t)
         (t (insert " ") (delete-region (- (point) 2) (- (point) 1)) t))
      (forward-line))))

(defun diff-sanity-check-hunk ()
  (let (;; Every modification is protected by a y-or-n-p, so it's probably
        ;; OK to override a read-only setting.
        (inhibit-read-only t))
    (save-excursion
      (cond
       ((not (looking-at diff-hunk-header-re))
        (error "Not recognizable hunk header"))

       ;; A context diff.
       ((eq (char-after) ?*)
        (if (not (looking-at "\\*\\{15\\}\\(?: .*\\)?\n\\*\\*\\* \\([0-9]+\\)\\(?:,\\([0-9]+\\)\\)? \\*\\*\\*\\*"))
            (error "Unrecognized context diff first hunk header format")
          (forward-line 2)
          (diff-sanity-check-context-hunk-half
	   (if (match-end 2)
	       (1+ (- (string-to-number (match-string 2))
		      (string-to-number (match-string 1))))
	     1))
          (if (not (looking-at diff-context-mid-hunk-header-re))
              (error "Unrecognized context diff second hunk header format")
            (forward-line)
            (diff-sanity-check-context-hunk-half
	     (if (match-end 2)
		 (1+ (- (string-to-number (match-string 2))
			(string-to-number (match-string 1))))
	       1)))))

       ;; A unified diff.
       ((eq (char-after) ?@)
        (if (not (looking-at diff-hunk-header-re-unified))
            (error "Unrecognized unified diff hunk header format")
          (let ((before (string-to-number (or (match-string 2) "1")))
                (after (string-to-number (or (match-string 4) "1"))))
            (forward-line)
            (while
                (pcase (char-after)
                  (?\s (cl-decf before) (cl-decf after) t)
                  (?-
                   (cond
                    ((and (looking-at diff-separator-re)
                          (zerop before) (zerop after))
                     nil)
                    ((and (looking-at diff-file-header-re)
                          (zerop before) (zerop after))
                     ;; No need to query: this is a case where two patches
                     ;; are concatenated and only counting the lines will
                     ;; give the right result.  Let's just add an empty
                     ;; line so that our code which doesn't count lines
                     ;; will not get confused.
                     (save-excursion (insert "\n")) nil)
                    (t
                     (cl-decf before) t)))
                  (?+ (cl-decf after) t)
                  (_
                   (cond
                    ((and diff-valid-unified-empty-line
                          ;; Not just (eolp) so we don't infloop at eob.
                          (eq (char-after) ?\n)
                          (> before 0) (> after 0))
                     (cl-decf before) (cl-decf after) t)
                    ((and (zerop before) (zerop after)) nil)
                    ((or (< before 0) (< after 0))
                     (error (if (or (zerop before) (zerop after))
                                "End of hunk ambiguously marked"
                              "Hunk seriously messed up")))
                    ((not (y-or-n-p (concat "Try to auto-fix " (if (eolp) "whitespace loss" "word-wrap damage") "? ")))
                     (error "Abort!"))
                    ((eolp) (insert " ") (forward-line -1) t)
                    (t (insert " ")
                       (delete-region (- (point) 2) (- (point) 1)) t))))
              (forward-line)))))

       ;; A plain diff.
       (t
        ;; TODO.
        )))))

(defun diff-hunk-text (hunk destp char-offset)
  "Return the literal source text from HUNK as (TEXT . OFFSET).
If DESTP is nil, TEXT is the source, otherwise the destination text.
CHAR-OFFSET is a char-offset in HUNK, and OFFSET is the corresponding
char-offset in TEXT."
  (with-temp-buffer
    (insert hunk)
    (goto-char (point-min))
    (let ((src-pos nil)
	  (dst-pos nil)
	  (divider-pos nil)
	  (num-pfx-chars 2))
      ;; Set the following variables:
      ;;  SRC-POS     buffer pos of the source part of the hunk or nil if none
      ;;  DST-POS     buffer pos of the destination part of the hunk or nil
      ;;  DIVIDER-POS buffer pos of any divider line separating the src & dst
      ;;  NUM-PFX-CHARS  number of line-prefix characters used by this format"
      (cond ((looking-at "^@@")
	     ;; unified diff
	     (setq num-pfx-chars 1)
	     (forward-line 1)
	     (setq src-pos (point) dst-pos (point)))
	    ((looking-at "^\\*\\*")
	     ;; context diff
	     (forward-line 2)
	     (setq src-pos (point))
	     (re-search-forward diff-context-mid-hunk-header-re nil t)
	     (forward-line 0)
	     (setq divider-pos (point))
	     (forward-line 1)
	     (setq dst-pos (point)))
	    ((looking-at "^[0-9]+a[0-9,]+$")
	     ;; normal diff, insert
	     (forward-line 1)
	     (setq dst-pos (point)))
	    ((looking-at "^[0-9,]+d[0-9]+$")
	     ;; normal diff, delete
	     (forward-line 1)
	     (setq src-pos (point)))
	    ((looking-at "^[0-9,]+c[0-9,]+$")
	     ;; normal diff, change
	     (forward-line 1)
	     (setq src-pos (point))
	     (re-search-forward "^---$" nil t)
	     (forward-line 0)
	     (setq divider-pos (point))
	     (forward-line 1)
	     (setq dst-pos (point)))
	    (t
	     (error "Unknown diff hunk type")))

      (if (if destp (null dst-pos) (null src-pos))
	  ;; Implied empty text
	  (if char-offset '("" . 0) "")

	;; For context diffs, either side can be empty, (if there's only
	;; added or only removed text).  We should then use the other side.
	(cond ((equal src-pos divider-pos) (setq src-pos dst-pos))
	      ((equal dst-pos (point-max)) (setq dst-pos src-pos)))

	(when char-offset (goto-char (+ (point-min) char-offset)))

	;; Get rid of anything except the desired text.
	(save-excursion
	  ;; Delete unused text region
	  (let ((keep (if destp dst-pos src-pos)))
	    (when (and divider-pos (> divider-pos keep))
	      (delete-region divider-pos (point-max)))
	    (delete-region (point-min) keep))
	  ;; Remove line-prefix characters, and unneeded lines (unified diffs).
	  (let ((kill-char (if destp ?- ?+)))
	    (goto-char (point-min))
	    (while (not (eobp))
	      (if (eq (char-after) kill-char)
		  (delete-region (point) (progn (forward-line 1) (point)))
		(delete-char num-pfx-chars)
		(forward-line 1)))))

	(let ((text (buffer-substring-no-properties (point-min) (point-max))))
	  (if char-offset (cons text (- (point) (point-min))) text))))))


(defun diff-find-text (text)
  "Return the buffer position (BEG . END) of the nearest occurrence of TEXT.
If TEXT isn't found, nil is returned."
  (let* ((orig (point))
	 (forw (and (search-forward text nil t)
		    (cons (match-beginning 0) (match-end 0))))
	 (back (and (goto-char (+ orig (length text)))
		    (search-backward text nil t)
		    (cons (match-beginning 0) (match-end 0)))))
    ;; Choose the closest match.
    (if (and forw back)
	(if (> (- (car forw) orig) (- orig (car back))) back forw)
      (or back forw))))

(defun diff-find-approx-text (text)
  "Return the buffer position (BEG . END) of the nearest occurrence of TEXT.
Whitespace differences are ignored."
  (let* ((orig (point))
	 (re (concat "^[ \t\n\f]*"
		     (mapconcat 'regexp-quote (split-string text) "[ \t\n\f]+")
		     "[ \t\n\f]*\n"))
	 (forw (and (re-search-forward re nil t)
		    (cons (match-beginning 0) (match-end 0))))
	 (back (and (goto-char (+ orig (length text)))
		    (re-search-backward re nil t)
		    (cons (match-beginning 0) (match-end 0)))))
    ;; Choose the closest match.
    (if (and forw back)
	(if (> (- (car forw) orig) (- orig (car back))) back forw)
      (or back forw))))

(defsubst diff-xor (a b) (if a (if (not b) a) b))

(defun diff-find-source-location (&optional other-file reverse noprompt)
  "Find out (BUF LINE-OFFSET POS SRC DST SWITCHED).
BUF is the buffer corresponding to the source file.
LINE-OFFSET is the offset between the expected and actual positions
  of the text of the hunk or nil if the text was not found.
POS is a pair (BEG . END) indicating the position of the text in the buffer.
SRC and DST are the two variants of text as returned by `diff-hunk-text'.
  SRC is the variant that was found in the buffer.
SWITCHED is non-nil if the patch is already applied.
NOPROMPT, if non-nil, means not to prompt the user."
  (save-excursion
    (let* ((other (diff-xor other-file diff-jump-to-old-file))
	   (char-offset (- (point) (diff-beginning-of-hunk t)))
           ;; Check that the hunk is well-formed.  Otherwise diff-mode and
           ;; the user may disagree on what constitutes the hunk
           ;; (e.g. because an empty line truncates the hunk mid-course),
           ;; leading to potentially nasty surprises for the user.
	   ;;
	   ;; Suppress check when NOPROMPT is non-nil (Bug#3033).
           (_ (unless noprompt (diff-sanity-check-hunk)))
	   (hunk (buffer-substring
                  (point) (save-excursion (diff-end-of-hunk) (point))))
	   (old (diff-hunk-text hunk reverse char-offset))
	   (new (diff-hunk-text hunk (not reverse) char-offset))
	   ;; Find the location specification.
	   (line (if (not (looking-at "\\(?:\\*\\{15\\}.*\n\\)?[-@* ]*\\([0-9,]+\\)\\([ acd+]+\\([0-9,]+\\)\\)?"))
		     (error "Can't find the hunk header")
		   (if other (match-string 1)
		     (if (match-end 3) (match-string 3)
		       (unless (re-search-forward
                                diff-context-mid-hunk-header-re nil t)
			 (error "Can't find the hunk separator"))
		       (match-string 1)))))
	   (file (or (diff-find-file-name other noprompt)
                     (error "Can't find the file")))
	   (buf (find-file-noselect file)))
      ;; Update the user preference if he so wished.
      (when (> (prefix-numeric-value other-file) 8)
	(setq diff-jump-to-old-file other))
      (with-current-buffer buf
        (goto-char (point-min)) (forward-line (1- (string-to-number line)))
	(let* ((orig-pos (point))
	       (switched nil)
	       ;; FIXME: Check for case where both OLD and NEW are found.
	       (pos (or (diff-find-text (car old))
			(progn (setq switched t) (diff-find-text (car new)))
			(progn (setq switched nil)
			       (condition-case nil
				   (diff-find-approx-text (car old))
				 (invalid-regexp nil)))	;Regex too big.
			(progn (setq switched t)
			       (condition-case nil
				   (diff-find-approx-text (car new))
				 (invalid-regexp nil)))	;Regex too big.
			(progn (setq switched nil) nil))))
	  (nconc
	   (list buf)
	   (if pos
	       (list (count-lines orig-pos (car pos)) pos)
	     (list nil (cons orig-pos (+ orig-pos (length (car old))))))
	   (if switched (list new old t) (list old new))))))))


(defun diff-hunk-status-msg (line-offset reversed dry-run)
  (let ((msg (if dry-run
		 (if reversed "already applied" "not yet applied")
	       (if reversed "undone" "applied"))))
    (message (cond ((null line-offset) "Hunk text not found")
		   ((= line-offset 0) "Hunk %s")
		   ((= line-offset 1) "Hunk %s at offset %d line")
		   (t "Hunk %s at offset %d lines"))
	     msg line-offset)))

(defvar diff-apply-hunk-to-backup-file nil)

(defun diff-apply-hunk (&optional reverse)
  "Apply the current hunk to the source file and go to the next.
By default, the new source file is patched, but if the variable
`diff-jump-to-old-file' is non-nil, then the old source file is
patched instead (some commands, such as `diff-goto-source' can change
the value of this variable when given an appropriate prefix argument).

With a prefix argument, REVERSE the hunk."
  (interactive "P")
  (diff-beginning-of-hunk t)
  (pcase-let ((`(,buf ,line-offset ,pos ,old ,new ,switched)
               ;; Sometimes we'd like to have the following behavior: if
               ;; REVERSE go to the new file, otherwise go to the old.
               ;; But that means that by default we use the old file, which is
               ;; the opposite of the default for diff-goto-source, and is thus
               ;; confusing.  Also when you don't know about it it's
               ;; pretty surprising.
               ;; TODO: make it possible to ask explicitly for this behavior.
               ;;
               ;; This is duplicated in diff-test-hunk.
               (diff-find-source-location nil reverse)))
    (cond
     ((null line-offset)
      (error "Can't find the text to patch"))
     ((with-current-buffer buf
        (and buffer-file-name
             (backup-file-name-p buffer-file-name)
             (not diff-apply-hunk-to-backup-file)
             (not (set (make-local-variable 'diff-apply-hunk-to-backup-file)
                       (yes-or-no-p (format "Really apply this hunk to %s? "
                                            (file-name-nondirectory
                                             buffer-file-name)))))))
      (error "%s"
	     (substitute-command-keys
              (format "Use %s\\[diff-apply-hunk] to apply it to the other file"
                      (if (not reverse) "\\[universal-argument] ")))))
     ((and switched
	   ;; A reversed patch was detected, perhaps apply it in reverse.
	   (not (save-window-excursion
		  (pop-to-buffer buf)
		  (goto-char (+ (car pos) (cdr old)))
		  (y-or-n-p
		   (if reverse
		       "Hunk hasn't been applied yet; apply it now? "
		     "Hunk has already been applied; undo it? ")))))
      (message "(Nothing done)"))
     (t
      ;; Apply the hunk
      (with-current-buffer buf
	(goto-char (car pos))
	(delete-region (car pos) (cdr pos))
	(insert (car new)))
      ;; Display BUF in a window
      (set-window-point (display-buffer buf) (+ (car pos) (cdr new)))
      (diff-hunk-status-msg line-offset (diff-xor switched reverse) nil)
      (when diff-advance-after-apply-hunk
	(diff-hunk-next))))))


(defun diff-test-hunk (&optional reverse)
  "See whether it's possible to apply the current hunk.
With a prefix argument, try to REVERSE the hunk."
  (interactive "P")
  (pcase-let ((`(,buf ,line-offset ,pos ,src ,_dst ,switched)
               (diff-find-source-location nil reverse)))
    (set-window-point (display-buffer buf) (+ (car pos) (cdr src)))
    (diff-hunk-status-msg line-offset (diff-xor reverse switched) t)))


(defun diff-kill-applied-hunks ()
  "Kill all hunks that have already been applied starting at point."
  (interactive)
  (while (not (eobp))
    (pcase-let ((`(,_buf ,line-offset ,_pos ,_src ,_dst ,switched)
                 (diff-find-source-location nil nil)))
      (if (and line-offset switched)
          (diff-hunk-kill)
        (diff-hunk-next)))))

(defalias 'diff-mouse-goto-source 'diff-goto-source)

(defun diff-goto-source (&optional other-file event)
  "Jump to the corresponding source line.
`diff-jump-to-old-file' (or its opposite if the OTHER-FILE prefix arg
is given) determines whether to jump to the old or the new file.
If the prefix arg is bigger than 8 (for example with \\[universal-argument] \\[universal-argument])
then `diff-jump-to-old-file' is also set, for the next invocations."
  (interactive (list current-prefix-arg last-input-event))
  ;; When pointing at a removal line, we probably want to jump to
  ;; the old location, and else to the new (i.e. as if reverting).
  ;; This is a convenient detail when using smerge-diff.
  (if event (posn-set-point (event-end event)))
  (let ((rev (not (save-excursion (beginning-of-line) (looking-at "[-<]")))))
    (pcase-let ((`(,buf ,line-offset ,pos ,src ,_dst ,switched)
                 (diff-find-source-location other-file rev)))
      (pop-to-buffer buf)
      (goto-char (+ (car pos) (cdr src)))
      (diff-hunk-status-msg line-offset (diff-xor rev switched) t))))


(defun diff-current-defun ()
  "Find the name of function at point.
For use in `add-log-current-defun-function'."
  ;; Kill change-log-default-name so it gets recomputed each time, since
  ;; each hunk may belong to another file which may belong to another
  ;; directory and hence have a different ChangeLog file.
  (kill-local-variable 'change-log-default-name)
  (save-excursion
    (when (looking-at diff-hunk-header-re)
      (forward-line 1)
      (re-search-forward "^[^ ]" nil t))
    (pcase-let ((`(,buf ,_line-offset ,pos ,src ,dst ,switched)
                 (ignore-errors         ;Signals errors in place of prompting.
                   ;; Use `noprompt' since this is used in which-func-mode
                   ;; and such.
                   (diff-find-source-location nil nil 'noprompt))))
      (when buf
        (beginning-of-line)
        (or (when (memq (char-after) '(?< ?-))
              ;; Cursor is pointing at removed text.  This could be a removed
              ;; function, in which case, going to the source buffer will
              ;; not help since the function is now removed.  Instead,
              ;; try to figure out the function name just from the
              ;; code-fragment.
              (let ((old (if switched dst src)))
                (with-temp-buffer
                  (insert (car old))
                  (funcall (buffer-local-value 'major-mode buf))
                  (goto-char (+ (point-min) (cdr old)))
                  (add-log-current-defun))))
            (with-current-buffer buf
              (goto-char (+ (car pos) (cdr src)))
              (add-log-current-defun)))))))

(defun diff-ignore-whitespace-hunk ()
  "Re-diff the current hunk, ignoring whitespace differences."
  (interactive)
  (let* ((char-offset (- (point) (diff-beginning-of-hunk t)))
	 (opts (pcase (char-after) (?@ "-bu") (?* "-bc") (_ "-b")))
	 (line-nb (and (or (looking-at "[^0-9]+\\([0-9]+\\)")
			   (error "Can't find line number"))
		       (string-to-number (match-string 1))))
	 (inhibit-read-only t)
	 (hunk (delete-and-extract-region
		(point) (save-excursion (diff-end-of-hunk) (point))))
	 (lead (make-string (1- line-nb) ?\n)) ;Line nums start at 1.
	 (file1 (make-temp-file "diff1"))
	 (file2 (make-temp-file "diff2"))
	 (coding-system-for-read buffer-file-coding-system)
	 old new)
    (unwind-protect
	(save-excursion
	  (setq old (diff-hunk-text hunk nil char-offset))
	  (setq new (diff-hunk-text hunk t char-offset))
	  (write-region (concat lead (car old)) nil file1 nil 'nomessage)
	  (write-region (concat lead (car new)) nil file2 nil 'nomessage)
	  (with-temp-buffer
	    (let ((status
		   (call-process diff-command nil t nil
				 opts file1 file2)))
	      (pcase status
		(0 nil)                 ;Nothing to reformat.
		(1 (goto-char (point-min))
                   ;; Remove the file-header.
                   (when (re-search-forward diff-hunk-header-re nil t)
                     (delete-region (point-min) (match-beginning 0))))
		(_ (goto-char (point-max))
		   (unless (bolp) (insert "\n"))
		   (insert hunk)))
	      (setq hunk (buffer-string))
	      (unless (memq status '(0 1))
		(error "Diff returned: %s" status)))))
      ;; Whatever happens, put back some equivalent text: either the new
      ;; one or the original one in case some error happened.
      (insert hunk)
      (delete-file file1)
      (delete-file file2))))

;;; Fine change highlighting.

(defface diff-refine-changed
  '((((class color) (min-colors 88) (background light))
     :background "#ffff55")
    (((class color) (min-colors 88) (background dark))
     :background "#aaaa22")
    (t :inverse-video t))
  "Face used for char-based changes shown by `diff-refine-hunk'."
  :group 'diff-mode)

(defface diff-refine-removed
  '((default
     :inherit diff-refine-changed)
    (((class color) (min-colors 88) (background light))
     :background "#ffbbbb")
    (((class color) (min-colors 88) (background dark))
     :background "#aa2222"))
  "Face used for removed characters shown by `diff-refine-hunk'."
  :group 'diff-mode
  :version "24.3")

(defface diff-refine-added
  '((default
     :inherit diff-refine-changed)
    (((class color) (min-colors 88) (background light))
     :background "#aaffaa")
    (((class color) (min-colors 88) (background dark))
     :background "#22aa22"))
  "Face used for added characters shown by `diff-refine-hunk'."
  :group 'diff-mode
  :version "24.3")

(defun diff-refine-preproc ()
  (while (re-search-forward "^[+>]" nil t)
    ;; Remove spurious changes due to the fact that one side of the hunk is
    ;; marked with leading + or > and the other with leading - or <.
    ;; We used to replace all the prefix chars with " " but this only worked
    ;; when we did char-based refinement (or when using
    ;; smerge-refine-weight-hack) since otherwise, the `forward' motion done
    ;; in chopup do not necessarily do the same as the ones in highlight
    ;; since the "_" is not treated the same as " ".
    (replace-match (cdr (assq (char-before) '((?+ . "-") (?> . "<"))))))
  )

(declare-function smerge-refine-subst "smerge-mode"
                  (beg1 end1 beg2 end2 props-c &optional preproc props-r props-a))

(defun diff--forward-while-leading-char (char bound)
  "Move point until reaching a line not starting with CHAR.
Return new point, if it was moved."
  (let ((pt nil))
    (while (and (< (point) bound) (eql (following-char) char))
      (forward-line 1)
      (setq pt (point)))
    pt))

(defun diff-refine-hunk ()
  "Highlight changes of hunk at point at a finer granularity."
  (interactive)
  (require 'smerge-mode)
  (when (diff--some-hunks-p)
    (save-excursion
      (diff-beginning-of-hunk t)
      (let* ((start (point))
             (style (diff-hunk-style))    ;Skips the hunk header as well.
             (beg (point))
             (props-c '((diff-mode . fine) (face diff-refine-changed)))
             (props-r '((diff-mode . fine) (face diff-refine-removed)))
             (props-a '((diff-mode . fine) (face diff-refine-added)))
             ;; Be careful to go back to `start' so diff-end-of-hunk gets
             ;; to read the hunk header's line info.
             (end (progn (goto-char start) (diff-end-of-hunk) (point))))

        (remove-overlays beg end 'diff-mode 'fine)

        (goto-char beg)
        (pcase style
          (`unified
           (while (re-search-forward "^-" end t)
             (let ((beg-del (progn (beginning-of-line) (point)))
                   beg-add end-add)
               (when (and (diff--forward-while-leading-char ?- end)
                          ;; Allow for "\ No newline at end of file".
                          (progn (diff--forward-while-leading-char ?\\ end)
                                 (setq beg-add (point)))
                          (diff--forward-while-leading-char ?+ end)
                          (progn (diff--forward-while-leading-char ?\\ end)
                                 (setq end-add (point))))
                 (smerge-refine-subst beg-del beg-add beg-add end-add
                                      nil 'diff-refine-preproc props-r props-a)))))
          (`context
           (let* ((middle (save-excursion (re-search-forward "^---")))
                  (other middle))
             (while (re-search-forward "^\\(?:!.*\n\\)+" middle t)
               (smerge-refine-subst (match-beginning 0) (match-end 0)
                                    (save-excursion
                                      (goto-char other)
                                      (re-search-forward "^\\(?:!.*\n\\)+" end)
                                      (setq other (match-end 0))
                                      (match-beginning 0))
                                    other
                                    (if diff-use-changed-face props-c)
                                    'diff-refine-preproc
                                    (unless diff-use-changed-face props-r)
                                    (unless diff-use-changed-face props-a)))))
          (_ ;; Normal diffs.
           (let ((beg1 (1+ (point))))
             (when (re-search-forward "^---.*\n" end t)
               ;; It's a combined add&remove, so there's something to do.
               (smerge-refine-subst beg1 (match-beginning 0)
                                    (match-end 0) end
                                    nil 'diff-refine-preproc props-r props-a)))))))))

(defun diff-undo (&optional arg)
  "Perform `undo', ignoring the buffer's read-only status."
  (interactive "P")
  (let ((inhibit-read-only t))
    (undo arg)))

(defun diff-add-change-log-entries-other-window ()
  "Iterate through the current diff and create ChangeLog entries.
I.e. like `add-change-log-entry-other-window' but applied to all hunks."
  (interactive)
  ;; XXX: Currently add-change-log-entry-other-window is only called
  ;; once per hunk.  Some hunks have multiple changes, it would be
  ;; good to call it for each change.
  (save-excursion
    (goto-char (point-min))
    (condition-case nil
        ;; Call add-change-log-entry-other-window for each hunk in
        ;; the diff buffer.
        (while (progn
                 (diff-hunk-next)
                 ;; Move to where the changes are,
                 ;; `add-change-log-entry-other-window' works better in
                 ;; that case.
                 (re-search-forward
                  (concat "\n[!+-<>]"
                          ;; If the hunk is a context hunk with an empty first
                          ;; half, recognize the "--- NNN,MMM ----" line
                          "\\(-- [0-9]+\\(,[0-9]+\\)? ----\n"
                          ;; and skip to the next non-context line.
                          "\\( .*\n\\)*[+]\\)?")
                  nil t))
          (save-excursion
            ;; FIXME: this pops up windows of all the buffers.
            (add-change-log-entry nil nil t nil t)))
      ;; When there's no more hunks, diff-hunk-next signals an error.
      (error nil))))

(defun diff-delete-trailing-whitespace (&optional other-file)
  "Remove trailing whitespace from lines modified in this diff.
This edits both the current Diff mode buffer and the patched
source file(s).  If `diff-jump-to-old-file' is non-nil, edit the
original (unpatched) source file instead.  With a prefix argument
OTHER-FILE, flip the choice of which source file to edit.

If a file referenced in the diff has no buffer and needs to be
fixed, visit it in a buffer."
  (interactive "P")
  (save-excursion
    (goto-char (point-min))
    (let* ((other (diff-xor other-file diff-jump-to-old-file))
  	   (modified-buffers nil)
  	   (style (save-excursion
  	   	    (when (re-search-forward diff-hunk-header-re nil t)
  	   	      (goto-char (match-beginning 0))
  	   	      (diff-hunk-style))))
  	   (regexp (concat "^[" (if other "-<" "+>") "!]"
  	   		   (if (eq style 'context) " " "")
  	   		   ".*?\\([ \t]+\\)$"))
	   (inhibit-read-only t)
	   (end-marker (make-marker))
	   hunk-end)
      ;; Move to the first hunk.
      (re-search-forward diff-hunk-header-re nil 1)
      (while (progn (save-excursion
		      (re-search-forward diff-hunk-header-re nil 1)
		      (setq hunk-end (point)))
		    (< (point) hunk-end))
	;; For context diffs, search only in the appropriate half of
	;; the hunk.  For other diffs, search within the entire hunk.
  	(if (not (eq style 'context))
  	    (set-marker end-marker hunk-end)
  	  (let ((mid-hunk
  		 (save-excursion
  		   (re-search-forward diff-context-mid-hunk-header-re hunk-end)
  		   (point))))
  	    (if other
  		(set-marker end-marker mid-hunk)
  	      (goto-char mid-hunk)
  	      (set-marker end-marker hunk-end))))
	(while (re-search-forward regexp end-marker t)
	  (let ((match-data (match-data)))
	    (pcase-let ((`(,buf ,line-offset ,pos ,src ,_dst ,_switched)
			 (diff-find-source-location other-file)))
	      (when line-offset
		;; Remove the whitespace in the Diff mode buffer.
		(set-match-data match-data)
		(replace-match "" t t nil 1)
		;; Remove the whitespace in the source buffer.
		(with-current-buffer buf
		  (save-excursion
		    (goto-char (+ (car pos) (cdr src)))
		    (beginning-of-line)
		    (when (re-search-forward "\\([ \t]+\\)$" (line-end-position) t)
		      (unless (memq buf modified-buffers)
			(push buf modified-buffers))
		      (replace-match ""))))))))
	(goto-char hunk-end))
      (if modified-buffers
	  (message "Deleted trailing whitespace from %s."
		   (mapconcat (lambda (buf) (format-message
					     "`%s'" (buffer-name buf)))
			      modified-buffers ", "))
	(message "No trailing whitespace to delete.")))))

;; provide the package
(provide 'diff-mode)

;;; Old Change Log from when diff-mode wasn't part of Emacs:
;; Revision 1.11  1999/10/09 23:38:29  monnier
;; (diff-mode-load-hook): dropped.
;; (auto-mode-alist): also catch *.diffs.
;; (diff-find-file-name, diff-mode):  add smarts to find the right file
;;     for *.rej files (that lack any file name indication).
;;
;; Revision 1.10  1999/09/30 15:32:11  monnier
;; added support for "\ No newline at end of file".
;;
;; Revision 1.9  1999/09/15 00:01:13  monnier
;; - added basic `compile' support.
;; - have diff-kill-hunk call diff-kill-file if it's the only hunk.
;; - diff-kill-file now tries to kill the leading garbage as well.
;;
;; Revision 1.8  1999/09/13 21:10:09  monnier
;; - don't use CL in the autoloaded code
;; - accept diffs using -T
;;
;; Revision 1.7  1999/09/05 20:53:03  monnier
;; interface to ediff-patch
;;
;; Revision 1.6  1999/09/01 20:55:13  monnier
;; (ediff=patch-file):  add bindings to call ediff-patch.
;; (diff-find-file-name):  taken out of diff-goto-source.
;; (diff-unified->context, diff-context->unified, diff-reverse-direction,
;;  diff-fixup-modifs):  only use the region if a prefix arg is given.
;;
;; Revision 1.5  1999/08/31 19:18:52  monnier
;; (diff-beginning-of-file, diff-prev-file):  fixed wrong parenthesis.
;;
;; Revision 1.4  1999/08/31 13:01:44  monnier
;; use `combine-after-change-calls' to minimize the slowdown of font-lock.
;;

;;; diff-mode.el ends here

debug log:

solving 1aa6c05662 ...
found 1aa6c05662 in https://yhetil.org/emacs/jwvmvabmh59.fsf@ceviche/
found aa8d77882e in https://git.savannah.gnu.org/cgit/emacs.git
preparing index
index prepared:
100644 aa8d77882ec26e245d74a494ddc2854904bf1eef	lisp/vc/diff-mode.el

applying [1/1] https://yhetil.org/emacs/jwvmvabmh59.fsf@ceviche/
diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index aa8d77882e..1aa6c05662 100644

Checking patch lisp/vc/diff-mode.el...
Applied patch lisp/vc/diff-mode.el cleanly.

index at:
100644 1aa6c05662a446a8471e8c0150a4d4a23510c0b7	lisp/vc/diff-mode.el

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/emacs.git
	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.