unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
blob 1ae094e52be6a50e445b0d7d870d0d88bdad7c8a 69990 bytes (raw)
name: src/intervals.c 	 # 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
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
 
/* Code for doing intervals.
   Copyright (C) 1993-1995, 1997-1998, 2001-2016 Free Software
   Foundation, Inc.

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/>.  */


/* NOTES:

   Have to ensure that we can't put symbol nil on a plist, or some
   functions may work incorrectly.

   An idea:  Have the owner of the tree keep count of splits and/or
   insertion lengths (in intervals), and balance after every N.

   Need to call *_left_hook when buffer is killed.

   Scan for zero-length, or 0-length to see notes about handling
   zero length interval-markers.

   There are comments around about freeing intervals.  It might be
   faster to explicitly free them (put them on the free list) than
   to GC them.

*/


#include <config.h>

#include <intprops.h>
#include "lisp.h"
#include "intervals.h"
#include "buffer.h"
#include "puresize.h"
#include "keymap.h"

/* Test for membership, allowing for t (actually any non-cons) to mean the
   universal set.  */

#define TMEM(sym, set) (CONSP (set) ? ! NILP (Fmemq (sym, set)) : ! NILP (set))

static Lisp_Object merge_properties_sticky (Lisp_Object, Lisp_Object);
static INTERVAL merge_interval_right (INTERVAL);
static INTERVAL reproduce_tree (INTERVAL, INTERVAL);
\f
/* Utility functions for intervals.  */

/* Use these functions to set pointer slots of struct interval.  */

static void
set_interval_left (INTERVAL i, INTERVAL left)
{
  i->left = left;
}

static void
set_interval_right (INTERVAL i, INTERVAL right)
{
  i->right = right;
}

/* Make the parent of D be whatever the parent of S is, regardless
   of the type.  This is used when balancing an interval tree.  */

static void
copy_interval_parent (INTERVAL d, INTERVAL s)
{
  d->up = s->up;
  d->up_obj = s->up_obj;
}

/* Create the root interval of some object, a buffer or string.  */

INTERVAL
create_root_interval (Lisp_Object parent)
{
  INTERVAL new;

  new = make_interval ();

  if (! STRINGP (parent))
    {
      new->total_length = (BUF_Z (XBUFFER (parent))
			   - BUF_BEG (XBUFFER (parent)));
      eassert (TOTAL_LENGTH (new) >= 0);
      set_buffer_intervals (XBUFFER (parent), new);
      new->position = BEG;
    }
  else
    {
      CHECK_IMPURE (parent, XSTRING (parent));
      new->total_length = SCHARS (parent);
      eassert (TOTAL_LENGTH (new) >= 0);
      set_string_intervals (parent, new);
      new->position = 0;
    }
  eassert (LENGTH (new) > 0);

  set_interval_object (new, parent);

  return new;
}

/* Make the interval TARGET have exactly the properties of SOURCE.  */

void
copy_properties (register INTERVAL source, register INTERVAL target)
{
  if (DEFAULT_INTERVAL_P (source) && DEFAULT_INTERVAL_P (target))
    return;

  COPY_INTERVAL_CACHE (source, target);
  set_interval_plist (target, Fcopy_sequence (source->plist));
}

/* Merge the properties of interval SOURCE into the properties
   of interval TARGET.  That is to say, each property in SOURCE
   is added to TARGET if TARGET has no such property as yet.  */

static void
merge_properties (register INTERVAL source, register INTERVAL target)
{
  register Lisp_Object o, sym, val;

  if (DEFAULT_INTERVAL_P (source) && DEFAULT_INTERVAL_P (target))
    return;

  MERGE_INTERVAL_CACHE (source, target);

  o = source->plist;
  while (CONSP (o))
    {
      sym = XCAR (o);
      o = XCDR (o);
      CHECK_CONS (o);

      val = target->plist;
      while (CONSP (val) && !EQ (XCAR (val), sym))
	{
	  val = XCDR (val);
	  if (!CONSP (val))
	    break;
	  val = XCDR (val);
	}

      if (NILP (val))
	{
	  val = XCAR (o);
	  set_interval_plist (target, Fcons (sym, Fcons (val, target->plist)));
	}
      o = XCDR (o);
    }
}

/* Return true if the two intervals have the same properties.  */

bool
intervals_equal (INTERVAL i0, INTERVAL i1)
{
  Lisp_Object i0_cdr, i0_sym;
  Lisp_Object i1_cdr, i1_val;

  if (DEFAULT_INTERVAL_P (i0) && DEFAULT_INTERVAL_P (i1))
    return true;

  if (DEFAULT_INTERVAL_P (i0) || DEFAULT_INTERVAL_P (i1))
    return false;

  i0_cdr = i0->plist;
  i1_cdr = i1->plist;
  while (CONSP (i0_cdr) && CONSP (i1_cdr))
    {
      i0_sym = XCAR (i0_cdr);
      i0_cdr = XCDR (i0_cdr);
      if (!CONSP (i0_cdr))
	return false;
      i1_val = i1->plist;
      while (CONSP (i1_val) && !EQ (XCAR (i1_val), i0_sym))
	{
	  i1_val = XCDR (i1_val);
	  if (!CONSP (i1_val))
	    return false;
	  i1_val = XCDR (i1_val);
	}

      /* i0 has something i1 doesn't.  */
      if (EQ (i1_val, Qnil))
	return false;

      /* i0 and i1 both have sym, but it has different values in each.  */
      if (!CONSP (i1_val)
	  || (i1_val = XCDR (i1_val), !CONSP (i1_val))
	  || !EQ (XCAR (i1_val), XCAR (i0_cdr)))
	return false;

      i0_cdr = XCDR (i0_cdr);

      i1_cdr = XCDR (i1_cdr);
      if (!CONSP (i1_cdr))
	return false;
      i1_cdr = XCDR (i1_cdr);
    }

  /* Lengths of the two plists were equal.  */
  return (NILP (i0_cdr) && NILP (i1_cdr));
}
\f

/* Traverse an interval tree TREE, performing FUNCTION on each node.
   No guarantee is made about the order of traversal.
   Pass FUNCTION two args: an interval, and ARG.  */

void
traverse_intervals_noorder (INTERVAL tree, void (*function) (INTERVAL, Lisp_Object), Lisp_Object arg)
{
  /* Minimize stack usage.  */
  while (tree)
    {
      (*function) (tree, arg);
      if (!tree->right)
	tree = tree->left;
      else
	{
	  traverse_intervals_noorder (tree->left, function, arg);
	  tree = tree->right;
	}
    }
}

/* Traverse an interval tree TREE, performing FUNCTION on each node.
   Pass FUNCTION two args: an interval, and ARG.  */

void
traverse_intervals (INTERVAL tree, ptrdiff_t position,
		    void (*function) (INTERVAL, Lisp_Object), Lisp_Object arg)
{
  while (tree)
    {
      traverse_intervals (tree->left, position, function, arg);
      position += LEFT_TOTAL_LENGTH (tree);
      tree->position = position;
      (*function) (tree, arg);
      position += LENGTH (tree); tree = tree->right;
    }
}
\f
#if 0

static int icount;
static int idepth;
static int zero_length;

/* These functions are temporary, for debugging purposes only.  */

INTERVAL search_interval, found_interval;

void
check_for_interval (INTERVAL i)
{
  if (i == search_interval)
    {
      found_interval = i;
      icount++;
    }
}

INTERVAL
search_for_interval (INTERVAL i, INTERVAL tree)
{
  icount = 0;
  search_interval = i;
  found_interval = NULL;
  traverse_intervals_noorder (tree, &check_for_interval, Qnil);
  return found_interval;
}

static void
inc_interval_count (INTERVAL i)
{
  icount++;
  if (LENGTH (i) == 0)
    zero_length++;
  if (depth > idepth)
    idepth = depth;
}

int
count_intervals (INTERVAL i)
{
  icount = 0;
  idepth = 0;
  zero_length = 0;
  traverse_intervals_noorder (i, &inc_interval_count, Qnil);

  return icount;
}

static INTERVAL
root_interval (INTERVAL interval)
{
  register INTERVAL i = interval;

  while (! ROOT_INTERVAL_P (i))
    i = INTERVAL_PARENT (i);

  return i;
}
#endif
\f
/* Assuming that a left child exists, perform the following operation:

     A		  B
    / \		 / \
   B       =>       A
  / \		   / \
     c		  c
*/

static INTERVAL
rotate_right (INTERVAL A)
{
  INTERVAL B = A->left;
  INTERVAL c = B->right;
  ptrdiff_t old_total = A->total_length;

  eassert (old_total > 0);
  eassert (LENGTH (A) > 0);
  eassert (LENGTH (B) > 0);

  /* Deal with any Parent of A;  make it point to B.  */
  if (! ROOT_INTERVAL_P (A))
    {
      if (AM_LEFT_CHILD (A))
	set_interval_left (INTERVAL_PARENT (A), B);
      else
	set_interval_right (INTERVAL_PARENT (A), B);
    }
  copy_interval_parent (B, A);

  /* Make B the parent of A.  */
  set_interval_right (B, A);
  set_interval_parent (A, B);

  /* Make A point to c.  */
  set_interval_left (A, c);
  if (c)
    set_interval_parent (c, A);

  /* A's total length is decreased by the length of B and its left child.  */
  A->total_length -= B->total_length - TOTAL_LENGTH (c);
  eassert (TOTAL_LENGTH (A) > 0);
  eassert (LENGTH (A) > 0);

  /* B must have the same total length of A.  */
  B->total_length = old_total;
  eassert (LENGTH (B) > 0);

  return B;
}

/* Assuming that a right child exists, perform the following operation:

    A               B
   / \	           / \
      B	   =>     A
     / \         / \
    c               c
*/

static INTERVAL
rotate_left (INTERVAL A)
{
  INTERVAL B = A->right;
  INTERVAL c = B->left;
  ptrdiff_t old_total = A->total_length;

  eassert (old_total > 0);
  eassert (LENGTH (A) > 0);
  eassert (LENGTH (B) > 0);

  /* Deal with any parent of A;  make it point to B.  */
  if (! ROOT_INTERVAL_P (A))
    {
      if (AM_LEFT_CHILD (A))
	set_interval_left (INTERVAL_PARENT (A), B);
      else
	set_interval_right (INTERVAL_PARENT (A), B);
    }
  copy_interval_parent (B, A);

  /* Make B the parent of A.  */
  set_interval_left (B, A);
  set_interval_parent (A, B);

  /* Make A point to c.  */
  set_interval_right (A, c);
  if (c)
    set_interval_parent (c, A);

  /* A's total length is decreased by the length of B and its right child.  */
  A->total_length -= B->total_length - TOTAL_LENGTH (c);
  eassert (TOTAL_LENGTH (A) > 0);
  eassert (LENGTH (A) > 0);

  /* B must have the same total length of A.  */
  B->total_length = old_total;
  eassert (LENGTH (B) > 0);

  return B;
}
\f
/* Balance an interval tree with the assumption that the subtrees
   themselves are already balanced.  */

static INTERVAL
balance_an_interval (INTERVAL i)
{
  register ptrdiff_t old_diff, new_diff;

  eassert (LENGTH (i) > 0);
  eassert (TOTAL_LENGTH (i) >= LENGTH (i));

  while (1)
    {
      old_diff = LEFT_TOTAL_LENGTH (i) - RIGHT_TOTAL_LENGTH (i);
      if (old_diff > 0)
	{
	  /* Since the left child is longer, there must be one.  */
	  new_diff = i->total_length - i->left->total_length
	    + RIGHT_TOTAL_LENGTH (i->left) - LEFT_TOTAL_LENGTH (i->left);
	  if (eabs (new_diff) >= old_diff)
	    break;
	  i = rotate_right (i);
	  balance_an_interval (i->right);
	}
      else if (old_diff < 0)
	{
	  /* Since the right child is longer, there must be one.  */
	  new_diff = i->total_length - i->right->total_length
	    + LEFT_TOTAL_LENGTH (i->right) - RIGHT_TOTAL_LENGTH (i->right);
	  if (eabs (new_diff) >= -old_diff)
	    break;
	  i = rotate_left (i);
	  balance_an_interval (i->left);
	}
      else
	break;
    }
  return i;
}

/* Balance INTERVAL, potentially stuffing it back into its parent
   Lisp Object.  */

static INTERVAL
balance_possible_root_interval (INTERVAL interval)
{
  Lisp_Object parent;
  bool have_parent = false;

  if (INTERVAL_HAS_OBJECT (interval))
    {
      have_parent = true;
      GET_INTERVAL_OBJECT (parent, interval);
    }
  else if (!INTERVAL_HAS_PARENT (interval))
    return interval;

  interval = balance_an_interval (interval);

  if (have_parent)
    {
      if (BUFFERP (parent))
	set_buffer_intervals (XBUFFER (parent), interval);
      else if (STRINGP (parent))
	set_string_intervals (parent, interval);
    }

  return interval;
}

/* Balance the interval tree TREE.  Balancing is by weight
   (the amount of text).  */

static INTERVAL
balance_intervals_internal (register INTERVAL tree)
{
  /* Balance within each side.  */
  if (tree->left)
    balance_intervals_internal (tree->left);
  if (tree->right)
    balance_intervals_internal (tree->right);
  return balance_an_interval (tree);
}

/* Advertised interface to balance intervals.  */

INTERVAL
balance_intervals (INTERVAL tree)
{
  return tree ? balance_intervals_internal (tree) : NULL;
}

/* Rebalance text properties of B.  */

static void
buffer_balance_intervals (struct buffer *b)
{
  INTERVAL i;

  eassert (b != NULL);
  i = buffer_intervals (b);
  if (i)
    set_buffer_intervals (b, balance_an_interval (i));
}

/* Split INTERVAL into two pieces, starting the second piece at
   character position OFFSET (counting from 0), relative to INTERVAL.
   INTERVAL becomes the left-hand piece, and the right-hand piece
   (second, lexicographically) is returned.

   The size and position fields of the two intervals are set based upon
   those of the original interval.  The property list of the new interval
   is reset, thus it is up to the caller to do the right thing with the
   result.

   Note that this does not change the position of INTERVAL;  if it is a root,
   it is still a root after this operation.  */

INTERVAL
split_interval_right (INTERVAL interval, ptrdiff_t offset)
{
  INTERVAL new = make_interval ();
  ptrdiff_t position = interval->position;
  ptrdiff_t new_length = LENGTH (interval) - offset;

  new->position = position + offset;
  set_interval_parent (new, interval);

  if (NULL_RIGHT_CHILD (interval))
    {
      set_interval_right (interval, new);
      new->total_length = new_length;
      eassert (LENGTH (new) > 0);
    }
  else
    {
      /* Insert the new node between INTERVAL and its right child.  */
      set_interval_right (new, interval->right);
      set_interval_parent (interval->right, new);
      set_interval_right (interval, new);
      new->total_length = new_length + new->right->total_length;
      balance_an_interval (new);
    }

  balance_possible_root_interval (interval);

  return new;
}

/* Split INTERVAL into two pieces, starting the second piece at
   character position OFFSET (counting from 0), relative to INTERVAL.
   INTERVAL becomes the right-hand piece, and the left-hand piece
   (first, lexicographically) is returned.

   The size and position fields of the two intervals are set based upon
   those of the original interval.  The property list of the new interval
   is reset, thus it is up to the caller to do the right thing with the
   result.

   Note that this does not change the position of INTERVAL;  if it is a root,
   it is still a root after this operation.  */

INTERVAL
split_interval_left (INTERVAL interval, ptrdiff_t offset)
{
  INTERVAL new = make_interval ();
  ptrdiff_t new_length = offset;

  new->position = interval->position;
  interval->position = interval->position + offset;
  set_interval_parent (new, interval);

  if (NULL_LEFT_CHILD (interval))
    {
      set_interval_left (interval, new);
      new->total_length = new_length;
      eassert (LENGTH (new) > 0);
    }
  else
    {
      /* Insert the new node between INTERVAL and its left child.  */
      set_interval_left (new, interval->left);
      set_interval_parent (new->left, new);
      set_interval_left (interval, new);
      new->total_length = new_length + new->left->total_length;
      balance_an_interval (new);
    }

  balance_possible_root_interval (interval);

  return new;
}
\f
/* Return the proper position for the first character
   described by the interval tree SOURCE.
   This is 1 if the parent is a buffer,
   0 if the parent is a string or if there is no parent.

   Don't use this function on an interval which is the child
   of another interval!  */

static int
interval_start_pos (INTERVAL source)
{
  Lisp_Object parent;

  if (!source)
    return 0;

  if (! INTERVAL_HAS_OBJECT (source))
    return 0;
  GET_INTERVAL_OBJECT (parent, source);
  if (BUFFERP (parent))
    return BUF_BEG (XBUFFER (parent));
  return 0;
}

/* Find the interval containing text position POSITION in the text
   represented by the interval tree TREE.  POSITION is a buffer
   position (starting from 1) or a string index (starting from 0).
   If POSITION is at the end of the buffer or string,
   return the interval containing the last character.

   The `position' field, which is a cache of an interval's position,
   is updated in the interval found.  Other functions (e.g., next_interval)
   will update this cache based on the result of find_interval.  */

INTERVAL
find_interval (register INTERVAL tree, register ptrdiff_t position)
{
  /* The distance from the left edge of the subtree at TREE
		    to POSITION.  */
  register ptrdiff_t relative_position;

  if (!tree)
    return NULL;

  relative_position = position;
  if (INTERVAL_HAS_OBJECT (tree))
    {
      Lisp_Object parent;
      GET_INTERVAL_OBJECT (parent, tree);
      if (BUFFERP (parent))
	relative_position -= BUF_BEG (XBUFFER (parent));
    }

  eassert (relative_position <= TOTAL_LENGTH (tree));

  tree = balance_possible_root_interval (tree);

  while (1)
    {
      eassert (tree);
      if (relative_position < LEFT_TOTAL_LENGTH (tree))
	{
	  tree = tree->left;
	}
      else if (! NULL_RIGHT_CHILD (tree)
	       && relative_position >= (TOTAL_LENGTH (tree)
					- RIGHT_TOTAL_LENGTH (tree)))
	{
	  relative_position -= (TOTAL_LENGTH (tree)
				- RIGHT_TOTAL_LENGTH (tree));
	  tree = tree->right;
	}
      else
	{
	  tree->position
	    = (position - relative_position /* left edge of *tree.  */
	       + LEFT_TOTAL_LENGTH (tree)); /* left edge of this interval.  */

	  return tree;
	}
    }
}
\f
/* Find the succeeding interval (lexicographically) to INTERVAL.
   Sets the `position' field based on that of INTERVAL (see
   find_interval).  */

INTERVAL
next_interval (register INTERVAL interval)
{
  register INTERVAL i = interval;
  register ptrdiff_t next_position;

  if (!i)
    return NULL;
  next_position = interval->position + LENGTH (interval);

  if (! NULL_RIGHT_CHILD (i))
    {
      i = i->right;
      while (! NULL_LEFT_CHILD (i))
	i = i->left;

      i->position = next_position;
      return i;
    }

  while (! NULL_PARENT (i))
    {
      if (AM_LEFT_CHILD (i))
	{
	  i = INTERVAL_PARENT (i);
	  i->position = next_position;
	  return i;
	}

      i = INTERVAL_PARENT (i);
    }

  return NULL;
}

/* Find the preceding interval (lexicographically) to INTERVAL.
   Sets the `position' field based on that of INTERVAL (see
   find_interval).  */

INTERVAL
previous_interval (register INTERVAL interval)
{
  register INTERVAL i;

  if (!interval)
    return NULL;

  if (! NULL_LEFT_CHILD (interval))
    {
      i = interval->left;
      while (! NULL_RIGHT_CHILD (i))
	i = i->right;

      i->position = interval->position - LENGTH (i);
      return i;
    }

  i = interval;
  while (! NULL_PARENT (i))
    {
      if (AM_RIGHT_CHILD (i))
	{
	  i = INTERVAL_PARENT (i);

	  i->position = interval->position - LENGTH (i);
	  return i;
	}
      i = INTERVAL_PARENT (i);
    }

  return NULL;
}

/* Find the interval containing POS given some non-NULL INTERVAL
   in the same tree.  Note that we need to update interval->position
   if we go down the tree.
   To speed up the process, we assume that the ->position of
   I and all its parents is already uptodate.  */
INTERVAL
update_interval (register INTERVAL i, ptrdiff_t pos)
{
  if (!i)
    return NULL;

  while (1)
    {
      if (pos < i->position)
	{
	  /* Move left.  */
	  if (pos >= i->position - TOTAL_LENGTH (i->left))
	    {
	      i->left->position = i->position - TOTAL_LENGTH (i->left)
		+ LEFT_TOTAL_LENGTH (i->left);
	      i = i->left;		/* Move to the left child.  */
	    }
	  else if (NULL_PARENT (i))
	    error ("Point before start of properties");
	  else
	      i = INTERVAL_PARENT (i);
	  continue;
	}
      else if (pos >= INTERVAL_LAST_POS (i))
	{
	  /* Move right.  */
	  if (pos < INTERVAL_LAST_POS (i) + TOTAL_LENGTH (i->right))
	    {
	      i->right->position = INTERVAL_LAST_POS (i)
		+ LEFT_TOTAL_LENGTH (i->right);
	      i = i->right;		/* Move to the right child.  */
	    }
	  else if (NULL_PARENT (i))
	    error ("Point %"pD"d after end of properties", pos);
	  else
	    i = INTERVAL_PARENT (i);
	  continue;
	}
      else
	return i;
    }
}

/* Effect an adjustment corresponding to the addition of LENGTH characters
   of text.  Do this by finding the interval containing POSITION in the
   interval tree TREE, and then adjusting all of its ancestors by adding
   LENGTH to them.

   If POSITION is the first character of an interval, meaning that point
   is actually between the two intervals, make the new text belong to
   the interval which is "sticky".

   If both intervals are "sticky", then make them belong to the left-most
   interval.  Another possibility would be to create a new interval for
   this text, and make it have the merged properties of both ends.  */

static INTERVAL
adjust_intervals_for_insertion (INTERVAL tree,
				ptrdiff_t position, ptrdiff_t length)
{
  INTERVAL i;
  INTERVAL temp;
  bool eobp = 0;
  Lisp_Object parent;
  ptrdiff_t offset;

  eassert (TOTAL_LENGTH (tree) > 0);

  GET_INTERVAL_OBJECT (parent, tree);
  offset = (BUFFERP (parent) ? BUF_BEG (XBUFFER (parent)) : 0);

  /* If inserting at point-max of a buffer, that position will be out
     of range.  Remember that buffer positions are 1-based.  */
  if (position >= TOTAL_LENGTH (tree) + offset)
    {
      position = TOTAL_LENGTH (tree) + offset;
      eobp = 1;
    }

  i = find_interval (tree, position);

  /* If in middle of an interval which is not sticky either way,
     we must not just give its properties to the insertion.
     So split this interval at the insertion point.

     Originally, the if condition here was this:
	(! (position == i->position || eobp)
	 && END_NONSTICKY_P (i)
	 && FRONT_NONSTICKY_P (i))
     But, these macros are now unreliable because of introduction of
     Vtext_property_default_nonsticky.  So, we always check properties
     one by one if POSITION is in middle of an interval.  */
  if (! (position == i->position || eobp))
    {
      Lisp_Object tail;
      Lisp_Object front, rear;

      tail = i->plist;

      /* Properties font-sticky and rear-nonsticky override
	 Vtext_property_default_nonsticky.  So, if they are t, we can
	 skip one by one checking of properties.  */
      rear = textget (i->plist, Qrear_nonsticky);
      if (! CONSP (rear) && ! NILP (rear))
	{
	  /* All properties are nonsticky.  We split the interval.  */
	  goto check_done;
	}
      front = textget (i->plist, Qfront_sticky);
      if (! CONSP (front) && ! NILP (front))
	{
	  /* All properties are sticky.  We don't split the interval.  */
	  tail = Qnil;
	  goto check_done;
	}

      /* Does any actual property pose an actual problem?  We break
	 the loop if we find a nonsticky property.  */
      for (; CONSP (tail); tail = Fcdr (XCDR (tail)))
	{
	  Lisp_Object prop, tmp;
	  prop = XCAR (tail);

	  /* Is this particular property front-sticky?  */
	  if (CONSP (front) && ! NILP (Fmemq (prop, front)))
	    continue;

	  /* Is this particular property rear-nonsticky?  */
	  if (CONSP (rear) && ! NILP (Fmemq (prop, rear)))
	    break;

	  /* Is this particular property recorded as sticky or
	     nonsticky in Vtext_property_default_nonsticky?  */
	  tmp = Fassq (prop, Vtext_property_default_nonsticky);
	  if (CONSP (tmp))
	    {
	      if (NILP (tmp))
		continue;
	      break;
	    }

	  /* By default, a text property is rear-sticky, thus we
	     continue the loop.  */
	}

    check_done:
      /* If any property is a real problem, split the interval.  */
      if (! NILP (tail))
	{
	  temp = split_interval_right (i, position - i->position);
	  copy_properties (i, temp);
	  i = temp;
	}
    }

  /* If we are positioned between intervals, check the stickiness of
     both of them.  We have to do this too, if we are at BEG or Z.  */
  if (position == i->position || eobp)
    {
      register INTERVAL prev;

      if (position == BEG)
	prev = 0;
      else if (eobp)
	{
	  prev = i;
	  i = 0;
	}
      else
	prev = previous_interval (i);

      /* Even if we are positioned between intervals, we default
	 to the left one if it exists.  We extend it now and split
	 off a part later, if stickiness demands it.  */
      for (temp = prev ? prev : i; temp; temp = INTERVAL_PARENT_OR_NULL (temp))
	{
	  temp->total_length += length;
	  temp = balance_possible_root_interval (temp);
	}

      /* If at least one interval has sticky properties,
	 we check the stickiness property by property.

	 Originally, the if condition here was this:
		(END_NONSTICKY_P (prev) || FRONT_STICKY_P (i))
	 But, these macros are now unreliable because of introduction
	 of Vtext_property_default_nonsticky.  So, we always have to
	 check stickiness of properties one by one.  If cache of
	 stickiness is implemented in the future, we may be able to
	 use those macros again.  */
      if (1)
	{
	  Lisp_Object pleft, pright;
	  struct interval newi;

	  RESET_INTERVAL (&newi);
	  pleft = prev ? prev->plist : Qnil;
	  pright = i ? i->plist : Qnil;
	  set_interval_plist (&newi, merge_properties_sticky (pleft, pright));

	  if (! prev) /* i.e. position == BEG */
	    {
	      if (! intervals_equal (i, &newi))
		{
		  i = split_interval_left (i, length);
		  set_interval_plist (i, newi.plist);
		}
	    }
	  else if (! intervals_equal (prev, &newi))
	    {
	      prev = split_interval_right (prev, position - prev->position);
	      set_interval_plist (prev, newi.plist);
	      if (i && intervals_equal (prev, i))
		merge_interval_right (prev);
	    }

	  /* We will need to update the cache here later.  */
	}
      else if (! prev && ! NILP (i->plist))
	{
	  /* Just split off a new interval at the left.
	     Since I wasn't front-sticky, the empty plist is ok.  */
	  i = split_interval_left (i, length);
	}
    }

  /* Otherwise just extend the interval.  */
  else
    {
      for (temp = i; temp; temp = INTERVAL_PARENT_OR_NULL (temp))
	{
	  temp->total_length += length;
	  temp = balance_possible_root_interval (temp);
	}
    }

  return tree;
}

/* Any property might be front-sticky on the left, rear-sticky on the left,
   front-sticky on the right, or rear-sticky on the right; the 16 combinations
   can be arranged in a matrix with rows denoting the left conditions and
   columns denoting the right conditions:
      _  __  _
_     FR FR FR FR
FR__   0  1  2  3
 _FR   4  5  6  7
FR     8  9  A  B
  FR   C  D  E  F

   left-props  = '(front-sticky (p8 p9 pa pb pc pd pe pf)
		   rear-nonsticky (p4 p5 p6 p7 p8 p9 pa pb)
		   p0 L p1 L p2 L p3 L p4 L p5 L p6 L p7 L
		   p8 L p9 L pa L pb L pc L pd L pe L pf L)
   right-props = '(front-sticky (p2 p3 p6 p7 pa pb pe pf)
		   rear-nonsticky (p1 p2 p5 p6 p9 pa pd pe)
		   p0 R p1 R p2 R p3 R p4 R p5 R p6 R p7 R
		   p8 R p9 R pa R pb R pc R pd R pe R pf R)

   We inherit from whoever has a sticky side facing us.  If both sides
   do (cases 2, 3, E, and F), then we inherit from whichever side has a
   non-nil value for the current property.  If both sides do, then we take
   from the left.

   When we inherit a property, we get its stickiness as well as its value.
   So, when we merge the above two lists, we expect to get this:

   result      = '(front-sticky (p6 p7 pa pb pc pd pe pf)
		   rear-nonsticky (p6 pa)
		   p0 L p1 L p2 L p3 L p6 R p7 R
		   pa R pb R pc L pd L pe L pf L)

   The optimizable special cases are:
       left rear-nonsticky = nil, right front-sticky = nil (inherit left)
       left rear-nonsticky = t,   right front-sticky = t   (inherit right)
       left rear-nonsticky = t,   right front-sticky = nil (inherit none)
*/

static Lisp_Object
merge_properties_sticky (Lisp_Object pleft, Lisp_Object pright)
{
  Lisp_Object props, front, rear;
  Lisp_Object lfront, lrear, rfront, rrear;
  Lisp_Object tail1, tail2, sym, lval, rval, cat;
  bool use_left, use_right, lpresent;

  props = Qnil;
  front = Qnil;
  rear  = Qnil;
  lfront = textget (pleft, Qfront_sticky);
  lrear  = textget (pleft, Qrear_nonsticky);
  rfront = textget (pright, Qfront_sticky);
  rrear  = textget (pright, Qrear_nonsticky);

  /* Go through each element of PRIGHT.  */
  for (tail1 = pright; CONSP (tail1); tail1 = Fcdr (XCDR (tail1)))
    {
      Lisp_Object tmp;

      sym = XCAR (tail1);

      /* Sticky properties get special treatment.  */
      if (EQ (sym, Qrear_nonsticky) || EQ (sym, Qfront_sticky))
	continue;

      rval = Fcar (XCDR (tail1));
      for (tail2 = pleft; CONSP (tail2); tail2 = Fcdr (XCDR (tail2)))
	if (EQ (sym, XCAR (tail2)))
	  break;

      /* Indicate whether the property is explicitly defined on the left.
	 (We know it is defined explicitly on the right
	 because otherwise we don't get here.)  */
      lpresent = ! NILP (tail2);
      lval = (NILP (tail2) ? Qnil : Fcar (Fcdr (tail2)));

      /* Even if lrear or rfront say nothing about the stickiness of
	 SYM, Vtext_property_default_nonsticky may give default
	 stickiness to SYM.  */
      tmp = Fassq (sym, Vtext_property_default_nonsticky);
      use_left = (lpresent
		  && ! (TMEM (sym, lrear)
			|| (CONSP (tmp) && ! NILP (XCDR (tmp)))));
      use_right = (TMEM (sym, rfront)
		   || (CONSP (tmp) && NILP (XCDR (tmp))));
      if (use_left && use_right)
	{
	  if (NILP (lval))
	    use_left = 0;
	  else if (NILP (rval))
	    use_right = 0;
	}
      if (use_left)
	{
	  /* We build props as (value sym ...) rather than (sym value ...)
	     because we plan to nreverse it when we're done.  */
	  props = Fcons (lval, Fcons (sym, props));
	  if (TMEM (sym, lfront))
	    front = Fcons (sym, front);
	  if (TMEM (sym, lrear))
	    rear = Fcons (sym, rear);
	}
      else if (use_right)
	{
	  props = Fcons (rval, Fcons (sym, props));
	  if (TMEM (sym, rfront))
	    front = Fcons (sym, front);
	  if (TMEM (sym, rrear))
	    rear = Fcons (sym, rear);
	}
    }

  /* Now go through each element of PLEFT.  */
  for (tail2 = pleft; CONSP (tail2); tail2 = Fcdr (XCDR (tail2)))
    {
      Lisp_Object tmp;

      sym = XCAR (tail2);

      /* Sticky properties get special treatment.  */
      if (EQ (sym, Qrear_nonsticky) || EQ (sym, Qfront_sticky))
	continue;

      /* If sym is in PRIGHT, we've already considered it.  */
      for (tail1 = pright; CONSP (tail1); tail1 = Fcdr (XCDR (tail1)))
	if (EQ (sym, XCAR (tail1)))
	  break;
      if (! NILP (tail1))
	continue;

      lval = Fcar (XCDR (tail2));

      /* Even if lrear or rfront say nothing about the stickiness of
	 SYM, Vtext_property_default_nonsticky may give default
	 stickiness to SYM.  */
      tmp = Fassq (sym, Vtext_property_default_nonsticky);

      /* Since rval is known to be nil in this loop, the test simplifies.  */
      if (! (TMEM (sym, lrear) || (CONSP (tmp) && ! NILP (XCDR (tmp)))))
	{
	  props = Fcons (lval, Fcons (sym, props));
	  if (TMEM (sym, lfront))
	    front = Fcons (sym, front);
	}
      else if (TMEM (sym, rfront) || (CONSP (tmp) && NILP (XCDR (tmp))))
	{
	  /* The value is nil, but we still inherit the stickiness
	     from the right.  */
	  front = Fcons (sym, front);
	  if (TMEM (sym, rrear))
	    rear = Fcons (sym, rear);
	}
    }
  props = Fnreverse (props);
  if (! NILP (rear))
    props = Fcons (Qrear_nonsticky, Fcons (Fnreverse (rear), props));

  cat = textget (props, Qcategory);
  if (! NILP (front)
      &&
      /* If we have inherited a front-stick category property that is t,
	 we don't need to set up a detailed one.  */
      ! (! NILP (cat) && SYMBOLP (cat)
	 && EQ (Fget (cat, Qfront_sticky), Qt)))
    props = Fcons (Qfront_sticky, Fcons (Fnreverse (front), props));
  return props;
}

\f
/* Delete a node I from its interval tree by merging its subtrees
   into one subtree which is then returned.  Caller is responsible for
   storing the resulting subtree into its parent.  */

static INTERVAL
delete_node (register INTERVAL i)
{
  register INTERVAL migrate, this;
  register ptrdiff_t migrate_amt;

  if (!i->left)
    return i->right;
  if (!i->right)
    return i->left;

  migrate = i->left;
  migrate_amt = i->left->total_length;
  this = i->right;
  this->total_length += migrate_amt;
  while (this->left)
    {
      this = this->left;
      this->total_length += migrate_amt;
    }
  set_interval_left (this, migrate);
  set_interval_parent (migrate, this);
  eassert (LENGTH (this) > 0);
  eassert (LENGTH (i->right) > 0);

  return i->right;
}

/* Delete interval I from its tree by calling `delete_node'
   and properly connecting the resultant subtree.

   I is presumed to be empty; that is, no adjustments are made
   for the length of I.  */

static void
delete_interval (register INTERVAL i)
{
  register INTERVAL parent;
  ptrdiff_t amt = LENGTH (i);

  eassert (amt == 0);		/* Only used on zero-length intervals now.  */

  if (ROOT_INTERVAL_P (i))
    {
      Lisp_Object owner;
      GET_INTERVAL_OBJECT (owner, i);
      parent = delete_node (i);
      if (parent)
	set_interval_object (parent, owner);

      if (BUFFERP (owner))
	set_buffer_intervals (XBUFFER (owner), parent);
      else if (STRINGP (owner))
	set_string_intervals (owner, parent);
      else
	emacs_abort ();

      return;
    }

  parent = INTERVAL_PARENT (i);
  if (AM_LEFT_CHILD (i))
    {
      set_interval_left (parent, delete_node (i));
      if (parent->left)
	set_interval_parent (parent->left, parent);
    }
  else
    {
      set_interval_right (parent, delete_node (i));
      if (parent->right)
	set_interval_parent (parent->right, parent);
    }
}
\f
/* Find the interval in TREE corresponding to the relative position
   FROM and delete as much as possible of AMOUNT from that interval.
   Return the amount actually deleted, and if the interval was
   zeroed-out, delete that interval node from the tree.

   Note that FROM is actually origin zero, aka relative to the
   leftmost edge of tree.  This is appropriate since we call ourselves
   recursively on subtrees.

   Do this by recursing down TREE to the interval in question, and
   deleting the appropriate amount of text.  */

static ptrdiff_t
interval_deletion_adjustment (register INTERVAL tree, register ptrdiff_t from,
			      register ptrdiff_t amount)
{
  register ptrdiff_t relative_position = from;

  if (!tree)
    return 0;

  /* Left branch.  */
  if (relative_position < LEFT_TOTAL_LENGTH (tree))
    {
      ptrdiff_t subtract = interval_deletion_adjustment (tree->left,
							 relative_position,
							 amount);
      tree->total_length -= subtract;
      eassert (LENGTH (tree) > 0);
      return subtract;
    }
  /* Right branch.  */
  else if (relative_position >= (TOTAL_LENGTH (tree)
				 - RIGHT_TOTAL_LENGTH (tree)))
    {
      ptrdiff_t subtract;

      relative_position -= (tree->total_length
			    - RIGHT_TOTAL_LENGTH (tree));
      subtract = interval_deletion_adjustment (tree->right,
					       relative_position,
					       amount);
      tree->total_length -= subtract;
      eassert (LENGTH (tree) > 0);
      return subtract;
    }
  /* Here -- this node.  */
  else
    {
      /* How much can we delete from this interval?  */
      ptrdiff_t my_amount = ((tree->total_length
			       - RIGHT_TOTAL_LENGTH (tree))
			      - relative_position);

      if (amount > my_amount)
	amount = my_amount;

      tree->total_length -= amount;
      eassert (LENGTH (tree) >= 0);
      if (LENGTH (tree) == 0)
	delete_interval (tree);

      return amount;
    }

  /* Never reach here.  */
}

/* Effect the adjustments necessary to the interval tree of BUFFER to
   correspond to the deletion of LENGTH characters from that buffer
   text.  The deletion is effected at position START (which is a
   buffer position, i.e. origin 1).  */

static void
adjust_intervals_for_deletion (struct buffer *buffer,
			       ptrdiff_t start, ptrdiff_t length)
{
  ptrdiff_t left_to_delete = length;
  INTERVAL tree = buffer_intervals (buffer);
  Lisp_Object parent;
  ptrdiff_t offset;

  GET_INTERVAL_OBJECT (parent, tree);
  offset = (BUFFERP (parent) ? BUF_BEG (XBUFFER (parent)) : 0);

  if (!tree)
    return;

  eassert (start <= offset + TOTAL_LENGTH (tree)
	   && start + length <= offset + TOTAL_LENGTH (tree));

  if (length == TOTAL_LENGTH (tree))
    {
      set_buffer_intervals (buffer, NULL);
      return;
    }

  if (ONLY_INTERVAL_P (tree))
    {
      tree->total_length -= length;
      eassert (LENGTH (tree) > 0);
      return;
    }

  if (start > offset + TOTAL_LENGTH (tree))
    start = offset + TOTAL_LENGTH (tree);
  while (left_to_delete > 0)
    {
      left_to_delete -= interval_deletion_adjustment (tree, start - offset,
						      left_to_delete);
      tree = buffer_intervals (buffer);
      if (left_to_delete == tree->total_length)
	{
	  set_buffer_intervals (buffer, NULL);
	  return;
	}
    }
}
\f
/* Make the adjustments necessary to the interval tree of BUFFER to
   represent an addition or deletion of LENGTH characters starting
   at position START.  Addition or deletion is indicated by the sign
   of LENGTH.  */

void
offset_intervals (struct buffer *buffer, ptrdiff_t start, ptrdiff_t length)
{
  if (!buffer_intervals (buffer) || length == 0)
    return;

  if (length > 0)
    adjust_intervals_for_insertion (buffer_intervals (buffer),
				    start, length);
  else
    adjust_intervals_for_deletion (buffer, start, -length);
}
\f
/* Merge interval I with its lexicographic successor. The resulting
   interval is returned, and has the properties of the original
   successor.  The properties of I are lost.  I is removed from the
   interval tree.

   IMPORTANT:
   The caller must verify that this is not the last (rightmost)
   interval.  */

static INTERVAL
merge_interval_right (register INTERVAL i)
{
  register ptrdiff_t absorb = LENGTH (i);
  register INTERVAL successor;

  /* Find the succeeding interval.  */
  if (! NULL_RIGHT_CHILD (i))      /* It's below us.  Add absorb
				      as we descend.  */
    {
      successor = i->right;
      while (! NULL_LEFT_CHILD (successor))
	{
	  successor->total_length += absorb;
	  eassert (LENGTH (successor) > 0);
	  successor = successor->left;
	}

      successor->total_length += absorb;
      eassert (LENGTH (successor) > 0);
      delete_interval (i);
      return successor;
    }

  /* Zero out this interval.  */
  i->total_length -= absorb;
  eassert (TOTAL_LENGTH (i) >= 0);

  successor = i;
  while (! NULL_PARENT (successor))	   /* It's above us.  Subtract as
					      we ascend.  */
    {
      if (AM_LEFT_CHILD (successor))
	{
	  successor = INTERVAL_PARENT (successor);
	  delete_interval (i);
	  return successor;
	}

      successor = INTERVAL_PARENT (successor);
      successor->total_length -= absorb;
      eassert (LENGTH (successor) > 0);
    }

  /* This must be the rightmost or last interval and cannot
     be merged right.  The caller should have known.  */
  emacs_abort ();
}
\f
/* Merge interval I with its lexicographic predecessor. The resulting
   interval is returned, and has the properties of the original predecessor.
   The properties of I are lost.  Interval node I is removed from the tree.

   IMPORTANT:
   The caller must verify that this is not the first (leftmost) interval.  */

INTERVAL
merge_interval_left (register INTERVAL i)
{
  register ptrdiff_t absorb = LENGTH (i);
  register INTERVAL predecessor;

  /* Find the preceding interval.  */
  if (! NULL_LEFT_CHILD (i))	/* It's below us. Go down,
				   adding ABSORB as we go.  */
    {
      predecessor = i->left;
      while (! NULL_RIGHT_CHILD (predecessor))
	{
	  predecessor->total_length += absorb;
	  eassert (LENGTH (predecessor) > 0);
	  predecessor = predecessor->right;
	}

      predecessor->total_length += absorb;
      eassert (LENGTH (predecessor) > 0);
      delete_interval (i);
      return predecessor;
    }

  /* Zero out this interval.  */
  i->total_length -= absorb;
  eassert (TOTAL_LENGTH (i) >= 0);

  predecessor = i;
  while (! NULL_PARENT (predecessor))	/* It's above us.  Go up,
					   subtracting ABSORB.  */
    {
      if (AM_RIGHT_CHILD (predecessor))
	{
	  predecessor = INTERVAL_PARENT (predecessor);
	  delete_interval (i);
	  return predecessor;
	}

      predecessor = INTERVAL_PARENT (predecessor);
      predecessor->total_length -= absorb;
      eassert (LENGTH (predecessor) > 0);
    }

  /* This must be the leftmost or first interval and cannot
     be merged left.  The caller should have known.  */
  emacs_abort ();
}
\f
/* Create a copy of SOURCE but with the default value of UP.  */

static INTERVAL
reproduce_interval (INTERVAL source)
{
  register INTERVAL target = make_interval ();

  eassert (LENGTH (source) > 0);

  target->total_length = source->total_length;
  target->position = source->position;

  copy_properties (source, target);

  if (! NULL_LEFT_CHILD (source))
    set_interval_left (target, reproduce_tree (source->left, target));
  if (! NULL_RIGHT_CHILD (source))
    set_interval_right (target, reproduce_tree (source->right, target));

  eassert (LENGTH (target) > 0);
  return target;
}

/* Make an exact copy of interval tree SOURCE which descends from
   PARENT.  This is done by recursing through SOURCE, copying
   the current interval and its properties, and then adjusting
   the pointers of the copy.  */

static INTERVAL
reproduce_tree (INTERVAL source, INTERVAL parent)
{
  INTERVAL target = reproduce_interval (source);
  set_interval_parent (target, parent);
  return target;
}

static INTERVAL
reproduce_tree_obj (INTERVAL source, Lisp_Object parent)
{
  INTERVAL target = reproduce_interval (source);
  set_interval_object (target, parent);
  return target;
}
\f
/* Insert the intervals of SOURCE into BUFFER at POSITION.
   LENGTH is the length of the text in SOURCE.

   The `position' field of the SOURCE intervals is assumed to be
   consistent with its parent; therefore, SOURCE must be an
   interval tree made with copy_interval or must be the whole
   tree of a buffer or a string.

   This is used in insdel.c when inserting Lisp_Strings into the
   buffer.  The text corresponding to SOURCE is already in the buffer
   when this is called.  The intervals of new tree are a copy of those
   belonging to the string being inserted; intervals are never
   shared.

   If the inserted text had no intervals associated, and we don't
   want to inherit the surrounding text's properties, this function
   simply returns -- offset_intervals should handle placing the
   text in the correct interval, depending on the sticky bits.

   If the inserted text had properties (intervals), then there are two
   cases -- either insertion happened in the middle of some interval,
   or between two intervals.

   If the text goes into the middle of an interval, then new intervals
   are created in the middle, and new text has the union of its properties
   and those of the text into which it was inserted.

   If the text goes between two intervals, then if neither interval
   had its appropriate sticky property set (front_sticky, rear_sticky),
   the new text has only its properties.  If one of the sticky properties
   is set, then the new text "sticks" to that region and its properties
   depend on merging as above.  If both the preceding and succeeding
   intervals to the new text are "sticky", then the new text retains
   only its properties, as if neither sticky property were set.  Perhaps
   we should consider merging all three sets of properties onto the new
   text...  */

void
graft_intervals_into_buffer (INTERVAL source, ptrdiff_t position,
			     ptrdiff_t length, struct buffer *buffer,
			     bool inherit)
{
  INTERVAL tree = buffer_intervals (buffer);
  INTERVAL under, over, this;
  ptrdiff_t over_used;

  /* If the new text has no properties, then with inheritance it
     becomes part of whatever interval it was inserted into.
     To prevent inheritance, we must clear out the properties
     of the newly inserted text.  */
  if (!source)
    {
      Lisp_Object buf;
      if (!inherit && tree && length > 0)
	{
	  XSETBUFFER (buf, buffer);
	  set_text_properties_1 (make_number (position),
				 make_number (position + length),
				 Qnil, buf,
				 find_interval (tree, position));
	}
      /* Shouldn't be necessary.  --Stef  */
      buffer_balance_intervals (buffer);
      return;
    }

  eassert (length == TOTAL_LENGTH (source));

  if ((BUF_Z (buffer) - BUF_BEG (buffer)) == length)
    {
      /* The inserted text constitutes the whole buffer, so
	 simply copy over the interval structure.  */
      Lisp_Object buf;

      XSETBUFFER (buf, buffer);
      set_buffer_intervals (buffer, reproduce_tree_obj (source, buf));
      buffer_intervals (buffer)->position = BUF_BEG (buffer);
      eassert (buffer_intervals (buffer)->up_obj == 1);
      return;
    }
  else if (!tree)
    {
      /* Create an interval tree in which to place a copy
	 of the intervals of the inserted string.  */
	Lisp_Object buf;

	XSETBUFFER (buf, buffer);
	tree = create_root_interval (buf);
    }
  /* Paranoia -- the text has already been added, so
     this buffer should be of non-zero length.  */
  eassert (TOTAL_LENGTH (tree) > 0);

  this = under = find_interval (tree, position);
  eassert (under);
  over = find_interval (source, interval_start_pos (source));

  /* Here for insertion in the middle of an interval.
     Split off an equivalent interval to the right,
     then don't bother with it any more.  */

  if (position > under->position)
    {
      INTERVAL end_unchanged
	= split_interval_left (this, position - under->position);
      copy_properties (under, end_unchanged);
      under->position = position;
    }
  else
    {
      /* This call may have some effect because previous_interval may
	 update `position' fields of intervals.  Thus, don't ignore it
	 for the moment.  Someone please tell me the truth (K.Handa).  */
      INTERVAL prev = previous_interval (under);
      (void) prev;
#if 0
      /* But, this code surely has no effect.  And, anyway,
	 END_NONSTICKY_P is unreliable now.  */
      if (prev && !END_NONSTICKY_P (prev))
	prev = 0;
#endif /* 0 */
    }

  /* Insertion is now at beginning of UNDER.  */

  /* The inserted text "sticks" to the interval `under',
     which means it gets those properties.
     The properties of under are the result of
     adjust_intervals_for_insertion, so stickiness has
     already been taken care of.  */

  /* OVER is the interval we are copying from next.
     OVER_USED says how many characters' worth of OVER
     have already been copied into target intervals.
     UNDER is the next interval in the target.  */
  over_used = 0;
  while (over)
    {
      /* If UNDER is longer than OVER, split it.  */
      if (LENGTH (over) - over_used < LENGTH (under))
	{
	  this = split_interval_left (under, LENGTH (over) - over_used);
	  copy_properties (under, this);
	}
      else
	this = under;

      /* THIS is now the interval to copy or merge into.
	 OVER covers all of it.  */
      if (inherit)
	merge_properties (over, this);
      else
	copy_properties (over, this);

      /* If THIS and OVER end at the same place,
	 advance OVER to a new source interval.  */
      if (LENGTH (this) == LENGTH (over) - over_used)
	{
	  over = next_interval (over);
	  over_used = 0;
	}
      else
	/* Otherwise just record that more of OVER has been used.  */
	over_used += LENGTH (this);

      /* Always advance to a new target interval.  */
      under = next_interval (this);
    }

  buffer_balance_intervals (buffer);
}

/* Get the value of property PROP from PLIST,
   which is the plist of an interval.
   We check for direct properties, for categories with property PROP,
   and for PROP appearing on the default-text-properties list.  */

Lisp_Object
textget (Lisp_Object plist, register Lisp_Object prop)
{
  return lookup_char_property (plist, prop, 1);
}

Lisp_Object
lookup_char_property (Lisp_Object plist, Lisp_Object prop, bool textprop)
{
  Lisp_Object tail, fallback = Qnil;

  for (tail = plist; CONSP (tail); tail = Fcdr (XCDR (tail)))
    {
      register Lisp_Object tem;
      tem = XCAR (tail);
      if (EQ (prop, tem))
	return Fcar (XCDR (tail));
      if (EQ (tem, Qcategory))
	{
	  tem = Fcar (XCDR (tail));
	  if (SYMBOLP (tem))
	    fallback = Fget (tem, prop);
	}
    }

  if (! NILP (fallback))
    return fallback;
  /* Check for alternative properties.  */
  tail = Fassq (prop, Vchar_property_alias_alist);
  if (! NILP (tail))
    {
      tail = XCDR (tail);
      for (; NILP (fallback) && CONSP (tail); tail = XCDR (tail))
	fallback = Fplist_get (plist, XCAR (tail));
    }

  if (textprop && NILP (fallback) && CONSP (Vdefault_text_properties))
    fallback = Fplist_get (Vdefault_text_properties, prop);
  return fallback;
}

\f
/* Set point in BUFFER "temporarily" to CHARPOS, which corresponds to
   byte position BYTEPOS.  */

void
temp_set_point_both (struct buffer *buffer,
		     ptrdiff_t charpos, ptrdiff_t bytepos)
{
  /* In a single-byte buffer, the two positions must be equal.  */
  eassert (BUF_ZV (buffer) != BUF_ZV_BYTE (buffer) || charpos == bytepos);

  eassert (charpos <= bytepos);
  eassert (charpos <= BUF_ZV (buffer) || BUF_BEGV (buffer) <= charpos);

  SET_BUF_PT_BOTH (buffer, charpos, bytepos);
}

/* Set point "temporarily", without checking any text properties.  */

void
temp_set_point (struct buffer *buffer, ptrdiff_t charpos)
{
  temp_set_point_both (buffer, charpos,
		       buf_charpos_to_bytepos (buffer, charpos));
}

/* Set point in BUFFER to CHARPOS.  If the target position is
   before an intangible character, move to an ok place.  */

void
set_point (ptrdiff_t charpos)
{
  set_point_both (charpos, buf_charpos_to_bytepos (current_buffer, charpos));
}

/* Set PT from MARKER's clipped position.  */

void
set_point_from_marker (Lisp_Object marker)
{
  ptrdiff_t charpos = clip_to_bounds (BEGV, marker_position (marker), ZV);
  ptrdiff_t bytepos = marker_byte_position (marker);

  /* Don't trust the byte position if the marker belongs to a
     different buffer.  */
  if (XMARKER (marker)->buffer != current_buffer)
    bytepos = buf_charpos_to_bytepos (current_buffer, charpos);
  else
    bytepos = clip_to_bounds (BEGV_BYTE, bytepos, ZV_BYTE);
  set_point_both (charpos, bytepos);
}

/* If there's an invisible character at position POS + TEST_OFFS in the
   current buffer, and the invisible property has a `stickiness' such that
   inserting a character at position POS would inherit the property it,
   return POS + ADJ, otherwise return POS.  If TEST_INTANG, intangibility
   is required as well as invisibility.

   TEST_OFFS should be either 0 or -1, and ADJ should be either 1 or -1.

   Note that `stickiness' is determined by overlay marker insertion types,
   if the invisible property comes from an overlay.  */

static ptrdiff_t
adjust_for_invis_intang (ptrdiff_t pos, ptrdiff_t test_offs, ptrdiff_t adj,
			 bool test_intang)
{
  Lisp_Object invis_propval, invis_overlay;
  Lisp_Object test_pos;

  if ((adj < 0 && pos + adj < BEGV) || (adj > 0 && pos + adj > ZV))
    /* POS + ADJ would be beyond the buffer bounds, so do no adjustment.  */
    return pos;

  test_pos = make_number (pos + test_offs);

  invis_propval
    = get_char_property_and_overlay (test_pos, Qinvisible, Qnil,
				     &invis_overlay);

  if ((!test_intang
       || ! NILP (Fget_char_property (test_pos, Qintangible, Qnil)))
      && TEXT_PROP_MEANS_INVISIBLE (invis_propval)
      /* This next test is true if the invisible property has a stickiness
	 such that an insertion at POS would inherit it.  */
      && (NILP (invis_overlay)
	  /* Invisible property is from a text-property.  */
	  ? (text_property_stickiness (Qinvisible, make_number (pos), Qnil)
	     == (test_offs == 0 ? 1 : -1))
	  /* Invisible property is from an overlay.  */
	  : (test_offs == 0
	     ? XMARKER (OVERLAY_START (invis_overlay))->insertion_type == 0
	     : XMARKER (OVERLAY_END (invis_overlay))->insertion_type == 1)))
    pos += adj;

  return pos;
}

/* Set point in BUFFER to CHARPOS, which corresponds to byte
   position BYTEPOS.  If the target position is
   before an intangible character, move to an ok place.  */

void
set_point_both (ptrdiff_t charpos, ptrdiff_t bytepos)
{
  register INTERVAL to, from, toprev, fromprev;
  ptrdiff_t buffer_point;
  ptrdiff_t old_position = PT;
  /* This ensures that we move forward past intangible text when the
     initial position is the same as the destination, in the rare
     instances where this is important, e.g. in line-move-finish
     (simple.el).  */
  bool backwards = charpos < old_position;
  bool have_overlays;
  ptrdiff_t original_position;

  bset_point_before_scroll (current_buffer, Qnil);

  if (charpos == PT)
    return;

  /* In a single-byte buffer, the two positions must be equal.  */
  eassert (ZV != ZV_BYTE || charpos == bytepos);

  /* Check this now, before checking if the buffer has any intervals.
     That way, we can catch conditions which break this sanity check
     whether or not there are intervals in the buffer.  */
  eassert (charpos <= ZV && charpos >= BEGV);

  have_overlays = buffer_has_overlays ();

  /* If we have no text properties and overlays,
     then we can do it quickly.  */
  if (!buffer_intervals (current_buffer) && ! have_overlays)
    {
      temp_set_point_both (current_buffer, charpos, bytepos);
      return;
    }

  /* Set TO to the interval containing the char after CHARPOS,
     and TOPREV to the interval containing the char before CHARPOS.
     Either one may be null.  They may be equal.  */
  to = find_interval (buffer_intervals (current_buffer), charpos);
  if (charpos == BEGV)
    toprev = 0;
  else if (to && to->position == charpos)
    toprev = previous_interval (to);
  else
    toprev = to;

  buffer_point = (PT == ZV ? ZV - 1 : PT);

  /* Set FROM to the interval containing the char after PT,
     and FROMPREV to the interval containing the char before PT.
     Either one may be null.  They may be equal.  */
  /* We could cache this and save time.  */
  from = find_interval (buffer_intervals (current_buffer), buffer_point);
  if (buffer_point == BEGV)
    fromprev = 0;
  else if (from && from->position == PT)
    fromprev = previous_interval (from);
  else if (buffer_point != PT)
    fromprev = from, from = 0;
  else
    fromprev = from;

  /* Moving within an interval.  */
  if (to == from && toprev == fromprev && INTERVAL_VISIBLE_P (to)
      && ! have_overlays)
    {
      temp_set_point_both (current_buffer, charpos, bytepos);
      return;
    }

  original_position = charpos;

  /* If the new position is between two intangible characters
     with the same intangible property value,
     move forward or backward until a change in that property.  */
  if (NILP (Vinhibit_point_motion_hooks)
      && ((to && toprev)
	  || have_overlays)
      /* Intangibility never stops us from positioning at the beginning
	 or end of the buffer, so don't bother checking in that case.  */
      && charpos != BEGV && charpos != ZV)
    {
      Lisp_Object pos;
      Lisp_Object intangible_propval;

      if (backwards)
	{
	  /* If the preceding character is both intangible and invisible,
	     and the invisible property is `rear-sticky', perturb it so
	     that the search starts one character earlier -- this ensures
	     that point can never move to the end of an invisible/
	     intangible/rear-sticky region.  */
	  charpos = adjust_for_invis_intang (charpos, -1, -1, 1);

	  XSETINT (pos, charpos);

	  /* If following char is intangible,
	     skip back over all chars with matching intangible property.  */

	  intangible_propval = Fget_char_property (pos, Qintangible, Qnil);

	  if (! NILP (intangible_propval))
	    {
	      while (XINT (pos) > BEGV
		     && EQ (Fget_char_property (make_number (XINT (pos) - 1),
						Qintangible, Qnil),
			    intangible_propval))
		pos = Fprevious_char_property_change (pos, Qnil);

	      /* Set CHARPOS from POS, and if the final intangible character
		 that we skipped over is also invisible, and the invisible
		 property is `front-sticky', perturb it to be one character
		 earlier -- this ensures that point can never move to the
		 beginning of an invisible/intangible/front-sticky region.  */
	      charpos = adjust_for_invis_intang (XINT (pos), 0, -1, 0);
	    }
	}
      else
	{
	  /* If the following character is both intangible and invisible,
	     and the invisible property is `front-sticky', perturb it so
	     that the search starts one character later -- this ensures
	     that point can never move to the beginning of an
	     invisible/intangible/front-sticky region.  */
	  charpos = adjust_for_invis_intang (charpos, 0, 1, 1);

	  XSETINT (pos, charpos);

	  /* If preceding char is intangible,
	     skip forward over all chars with matching intangible property.  */

	  intangible_propval = Fget_char_property (make_number (charpos - 1),
						   Qintangible, Qnil);

	  if (! NILP (intangible_propval))
	    {
	      while (XINT (pos) < ZV
		     && EQ (Fget_char_property (pos, Qintangible, Qnil),
			    intangible_propval))
		pos = Fnext_char_property_change (pos, Qnil);

	      /* Set CHARPOS from POS, and if the final intangible character
		 that we skipped over is also invisible, and the invisible
		 property is `rear-sticky', perturb it to be one character
		 later -- this ensures that point can never move to the
		 end of an invisible/intangible/rear-sticky region.  */
	      charpos = adjust_for_invis_intang (XINT (pos), -1, 1, 0);
	    }
	}

      bytepos = buf_charpos_to_bytepos (current_buffer, charpos);
    }

  if (charpos != original_position)
    {
      /* Set TO to the interval containing the char after CHARPOS,
	 and TOPREV to the interval containing the char before CHARPOS.
	 Either one may be null.  They may be equal.  */
      to = find_interval (buffer_intervals (current_buffer), charpos);
      if (charpos == BEGV)
	toprev = 0;
      else if (to && to->position == charpos)
	toprev = previous_interval (to);
      else
	toprev = to;
    }

  /* Here TO is the interval after the stopping point
     and TOPREV is the interval before the stopping point.
     One or the other may be null.  */

  temp_set_point_both (current_buffer, charpos, bytepos);

  /* We run point-left and point-entered hooks here, if the
     two intervals are not equivalent.  These hooks take
     (old_point, new_point) as arguments.  */
  if (NILP (Vinhibit_point_motion_hooks)
      && (! intervals_equal (from, to)
	  || ! intervals_equal (fromprev, toprev)))
    {
      Lisp_Object leave_after, leave_before, enter_after, enter_before;

      if (fromprev)
	leave_before = textget (fromprev->plist, Qpoint_left);
      else
	leave_before = Qnil;

      if (from)
	leave_after = textget (from->plist, Qpoint_left);
      else
	leave_after = Qnil;

      if (toprev)
	enter_before = textget (toprev->plist, Qpoint_entered);
      else
	enter_before = Qnil;

      if (to)
	enter_after = textget (to->plist, Qpoint_entered);
      else
	enter_after = Qnil;

      if (! EQ (leave_before, enter_before) && !NILP (leave_before))
      	call2 (leave_before, make_number (old_position),
      	       make_number (charpos));
      if (! EQ (leave_after, enter_after) && !NILP (leave_after))
      	call2 (leave_after, make_number (old_position),
      	       make_number (charpos));

      if (! EQ (enter_before, leave_before) && !NILP (enter_before))
      	call2 (enter_before, make_number (old_position),
      	       make_number (charpos));
      if (! EQ (enter_after, leave_after) && !NILP (enter_after))
      	call2 (enter_after, make_number (old_position),
      	       make_number (charpos));
    }
}
\f
/* Move point to POSITION, unless POSITION is inside an intangible
   segment that reaches all the way to point.  */

void
move_if_not_intangible (ptrdiff_t position)
{
  Lisp_Object pos;
  Lisp_Object intangible_propval;

  XSETINT (pos, position);

  if (! NILP (Vinhibit_point_motion_hooks))
    /* If intangible is inhibited, always move point to POSITION.  */
    ;
  else if (PT < position && XINT (pos) < ZV)
    {
      /* We want to move forward, so check the text before POSITION.  */

      intangible_propval = Fget_char_property (pos,
					       Qintangible, Qnil);

      /* If following char is intangible,
	 skip back over all chars with matching intangible property.  */
      if (! NILP (intangible_propval))
	while (XINT (pos) > BEGV
	       && EQ (Fget_char_property (make_number (XINT (pos) - 1),
					  Qintangible, Qnil),
		      intangible_propval))
	  pos = Fprevious_char_property_change (pos, Qnil);
    }
  else if (XINT (pos) > BEGV)
    {
      /* We want to move backward, so check the text after POSITION.  */

      intangible_propval = Fget_char_property (make_number (XINT (pos) - 1),
					       Qintangible, Qnil);

      /* If following char is intangible,
	 skip forward over all chars with matching intangible property.  */
      if (! NILP (intangible_propval))
	while (XINT (pos) < ZV
	       && EQ (Fget_char_property (pos, Qintangible, Qnil),
		      intangible_propval))
	  pos = Fnext_char_property_change (pos, Qnil);

    }
  else if (position < BEGV)
    position = BEGV;
  else if (position > ZV)
    position = ZV;

  /* If the whole stretch between PT and POSITION isn't intangible,
     try moving to POSITION (which means we actually move farther
     if POSITION is inside of intangible text).  */

  if (XINT (pos) != PT)
    SET_PT (position);
}
\f
/* If text at position POS has property PROP, set *VAL to the property
   value, *START and *END to the beginning and end of a region that
   has the same property, and return true.  Otherwise return false.

   OBJECT is the string or buffer to look for the property in;
   nil means the current buffer. */

bool
get_property_and_range (ptrdiff_t pos, Lisp_Object prop, Lisp_Object *val,
			ptrdiff_t *start, ptrdiff_t *end, Lisp_Object object)
{
  INTERVAL i, prev, next;

  if (NILP (object))
    i = find_interval (buffer_intervals (current_buffer), pos);
  else if (BUFFERP (object))
    i = find_interval (buffer_intervals (XBUFFER (object)), pos);
  else if (STRINGP (object))
    i = find_interval (string_intervals (object), pos);
  else
    emacs_abort ();

  if (!i || (i->position + LENGTH (i) <= pos))
    return 0;
  *val = textget (i->plist, prop);
  if (NILP (*val))
    return 0;

  next = i;			/* remember it in advance */
  prev = previous_interval (i);
  while (prev
	 && EQ (*val, textget (prev->plist, prop)))
    i = prev, prev = previous_interval (prev);
  *start = i->position;

  next = next_interval (i);
  while (next && EQ (*val, textget (next->plist, prop)))
    i = next, next = next_interval (next);
  *end = i->position + LENGTH (i);

  return 1;
}
\f
/* Return the proper local keymap TYPE for position POSITION in
   BUFFER; TYPE should be one of `keymap' or `local-map'.  Use the map
   specified by the PROP property, if any.  Otherwise, if TYPE is
   `local-map' use BUFFER's local map.  */

Lisp_Object
get_local_map (ptrdiff_t position, struct buffer *buffer, Lisp_Object type)
{
  Lisp_Object prop, lispy_position, lispy_buffer;
  ptrdiff_t old_begv, old_zv, old_begv_byte, old_zv_byte;

  position = clip_to_bounds (BUF_BEGV (buffer), position, BUF_ZV (buffer));

  /* Ignore narrowing, so that a local map continues to be valid even if
     the visible region contains no characters and hence no properties.  */
  old_begv = BUF_BEGV (buffer);
  old_zv = BUF_ZV (buffer);
  old_begv_byte = BUF_BEGV_BYTE (buffer);
  old_zv_byte = BUF_ZV_BYTE (buffer);

  SET_BUF_BEGV_BOTH (buffer, BUF_BEG (buffer), BUF_BEG_BYTE (buffer));
  SET_BUF_ZV_BOTH (buffer, BUF_Z (buffer), BUF_Z_BYTE (buffer));

  XSETFASTINT (lispy_position, position);
  XSETBUFFER (lispy_buffer, buffer);
  /* First check if the CHAR has any property.  This is because when
     we click with the mouse, the mouse pointer is really pointing
     to the CHAR after POS.  */
  prop = Fget_char_property (lispy_position, type, lispy_buffer);
  /* If not, look at the POS's properties.  This is necessary because when
     editing a field with a `local-map' property, we want insertion at the end
     to obey the `local-map' property.  */
  if (NILP (prop))
    prop = Fget_pos_property (lispy_position, type, lispy_buffer);

  SET_BUF_BEGV_BOTH (buffer, old_begv, old_begv_byte);
  SET_BUF_ZV_BOTH (buffer, old_zv, old_zv_byte);

  /* Use the local map only if it is valid.  */
  prop = get_keymap (prop, 0, 0);
  if (CONSP (prop))
    return prop;

  if (EQ (type, Qkeymap))
    return Qnil;
  else
    return BVAR (buffer, keymap);
}
\f
/* Produce an interval tree reflecting the intervals in
   TREE from START to START + LENGTH.
   The new interval tree has no parent and has a starting-position of 0.  */

INTERVAL
copy_intervals (INTERVAL tree, ptrdiff_t start, ptrdiff_t length)
{
  register INTERVAL i, new, t;
  register ptrdiff_t got, prevlen;

  if (!tree || length <= 0)
    return NULL;

  i = find_interval (tree, start);
  eassert (i && LENGTH (i) > 0);

  /* If there is only one interval and it's the default, return nil.  */
  if ((start - i->position + 1 + length) < LENGTH (i)
      && DEFAULT_INTERVAL_P (i))
    return NULL;

  new = make_interval ();
  new->position = 0;
  got = (LENGTH (i) - (start - i->position));
  new->total_length = length;
  eassert (TOTAL_LENGTH (new) >= 0);
  copy_properties (i, new);

  t = new;
  prevlen = got;
  while (got < length)
    {
      i = next_interval (i);
      t = split_interval_right (t, prevlen);
      copy_properties (i, t);
      prevlen = LENGTH (i);
      got += prevlen;
    }

  return balance_an_interval (new);
}

/* Give STRING the properties of BUFFER from POSITION to LENGTH.  */

void
copy_intervals_to_string (Lisp_Object string, struct buffer *buffer,
			  ptrdiff_t position, ptrdiff_t length)
{
  INTERVAL interval_copy = copy_intervals (buffer_intervals (buffer),
					   position, length);
  if (!interval_copy)
    return;

  set_interval_object (interval_copy, string);
  set_string_intervals (string, interval_copy);
}
\f
/* Return true if strings S1 and S2 have identical properties.
   Assume they have identical characters.  */

bool
compare_string_intervals (Lisp_Object s1, Lisp_Object s2)
{
  INTERVAL i1, i2;
  ptrdiff_t pos = 0;
  ptrdiff_t end = SCHARS (s1);

  i1 = find_interval (string_intervals (s1), 0);
  i2 = find_interval (string_intervals (s2), 0);

  while (pos < end)
    {
      /* Determine how far we can go before we reach the end of I1 or I2.  */
      ptrdiff_t len1 = (i1 != 0 ? INTERVAL_LAST_POS (i1) : end) - pos;
      ptrdiff_t len2 = (i2 != 0 ? INTERVAL_LAST_POS (i2) : end) - pos;
      ptrdiff_t distance = min (len1, len2);

      /* If we ever find a mismatch between the strings,
	 they differ.  */
      if (! intervals_equal (i1, i2))
	return 0;

      /* Advance POS till the end of the shorter interval,
	 and advance one or both interval pointers for the new position.  */
      pos += distance;
      if (len1 == distance)
	i1 = next_interval (i1);
      if (len2 == distance)
	i2 = next_interval (i2);
    }
  return 1;
}
\f
/* Recursively adjust interval I in the current buffer
   for setting enable_multibyte_characters to MULTI_FLAG.
   The range of interval I is START ... END in characters,
   START_BYTE ... END_BYTE in bytes.  */

static void
set_intervals_multibyte_1 (INTERVAL i, bool multi_flag,
			   ptrdiff_t start, ptrdiff_t start_byte,
			   ptrdiff_t end, ptrdiff_t end_byte)
{
  /* Fix the length of this interval.  */
  if (multi_flag)
    i->total_length = end - start;
  else
    i->total_length = end_byte - start_byte;
  eassert (TOTAL_LENGTH (i) >= 0);

  if (TOTAL_LENGTH (i) == 0)
    {
      delete_interval (i);
      return;
    }

  /* Recursively fix the length of the subintervals.  */
  if (i->left)
    {
      ptrdiff_t left_end, left_end_byte;

      if (multi_flag)
	{
	  ptrdiff_t temp;
	  left_end_byte = start_byte + LEFT_TOTAL_LENGTH (i);
	  left_end = BYTE_TO_CHAR (left_end_byte);

	  temp = CHAR_TO_BYTE (left_end);

	  /* If LEFT_END_BYTE is in the middle of a character,
	     adjust it and LEFT_END to a char boundary.  */
	  if (left_end_byte > temp)
	    {
	      left_end_byte = temp;
	    }
	  if (left_end_byte < temp)
	    {
	      left_end--;
	      left_end_byte = CHAR_TO_BYTE (left_end);
	    }
	}
      else
	{
	  left_end = start + LEFT_TOTAL_LENGTH (i);
	  left_end_byte = CHAR_TO_BYTE (left_end);
	}

      set_intervals_multibyte_1 (i->left, multi_flag, start, start_byte,
				 left_end, left_end_byte);
    }
  if (i->right)
    {
      ptrdiff_t right_start_byte, right_start;

      if (multi_flag)
	{
	  ptrdiff_t temp;

	  right_start_byte = end_byte - RIGHT_TOTAL_LENGTH (i);
	  right_start = BYTE_TO_CHAR (right_start_byte);

	  /* If RIGHT_START_BYTE is in the middle of a character,
	     adjust it and RIGHT_START to a char boundary.  */
	  temp = CHAR_TO_BYTE (right_start);

	  if (right_start_byte < temp)
	    {
	      right_start_byte = temp;
	    }
	  if (right_start_byte > temp)
	    {
	      right_start++;
	      right_start_byte = CHAR_TO_BYTE (right_start);
	    }
	}
      else
	{
	  right_start = end - RIGHT_TOTAL_LENGTH (i);
	  right_start_byte = CHAR_TO_BYTE (right_start);
	}

      set_intervals_multibyte_1 (i->right, multi_flag,
				 right_start, right_start_byte,
				 end, end_byte);
    }

  /* Rounding to char boundaries can theoretically make this interval
     spurious.  If so, delete one child, and copy its property list
     to this interval.  */
  if (LEFT_TOTAL_LENGTH (i) + RIGHT_TOTAL_LENGTH (i) >= TOTAL_LENGTH (i))
    {
      if ((i)->left)
	{
	  set_interval_plist (i, i->left->plist);
	  (i)->left->total_length = 0;
	  delete_interval ((i)->left);
	}
      else
	{
	  set_interval_plist (i, i->right->plist);
	  (i)->right->total_length = 0;
	  delete_interval ((i)->right);
	}
    }
}

/* Update the intervals of the current buffer
   to fit the contents as multibyte (if MULTI_FLAG)
   or to fit them as non-multibyte (if not MULTI_FLAG).  */

void
set_intervals_multibyte (bool multi_flag)
{
  INTERVAL i = buffer_intervals (current_buffer);

  if (i)
    set_intervals_multibyte_1 (i, multi_flag, BEG, BEG_BYTE, Z, Z_BYTE);
}

debug log:

solving 1ae094e ...
found 1ae094e in https://yhetil.org/emacs-devel/87h95olvg0.fsf@gmail.com/
found e797e25 in https://git.savannah.gnu.org/cgit/emacs.git
preparing index
index prepared:
100644 e797e25ce9c48ec68819718bc5e18d33a42be8b9	src/intervals.c

applying [1/1] https://yhetil.org/emacs-devel/87h95olvg0.fsf@gmail.com/
diff --git a/src/intervals.c b/src/intervals.c
index e797e25..1ae094e 100644

Checking patch src/intervals.c...
Applied patch src/intervals.c cleanly.

index at:
100644 1ae094e52be6a50e445b0d7d870d0d88bdad7c8a	src/intervals.c

(*) 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 public inbox

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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).