about summary refs log tree commit diff stats
path: root/charterm/charterm.rkt
blob: cae12098b3d34f55cce4e86c376b28863a0eb62f (plain) (blame)
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
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
#lang racket/base
;; Copyright (c) Neil Van Dyke.  See file "info.rkt".

(require (for-syntax racket/base
                     racket/syntax)
         racket/system
         (planet neil/mcfly))

(doc (section "Introduction")

     (para "The "
           "CharTerm"
           " package provides a Racket interface for character-cell video
display terminals on Unix-like systems -- such as for "
           (as-index "GNU Screen")
           " and "
           (as-index (code "tmux"))
           " sessions on "
           (index '("cloud server" "server") "cloud servers")
           ", "
           (as-index "XTerm")
           " windows on a workstation desktop, and some older hardware
terminals (even the venerable "
           (as-index "DEC VT100")
           ").  Currently, it implements a subset of features available on most
terminals.")

     (para "This package could be used to implement a status/management console
for a Racket-based server process (perhaps run in GNU Screen or "
           (code "tmux")
           " on a server machine, to be detached and reattached from SSH
sessions), a lightweight user interface for a systems tool, a command-line
REPL, a text editor, creative retro uses of old equipment, and, perhaps most
importantly, a "
           ;; (hyperlink "http://en.wikipedia.org/wiki/Rogue_%28computer_game%29"
           "Rogue-like"
           ;;)
           " application.")

     (para "The "
           "CharTerm"
           " package does not include any native code (such as from "
           (as-index (code "terminfo"))
           ", "
           (as-index (code "termcap"))
           ", "
           (as-index (code "curses"))
           ", or "
           (as-index (code "ncurses"))
           ") in the Racket process,
such as through the Racket FFI or C extensions, so there is less potential for
a problem involving native code to threaten the reliability or security of a
program.  "
           "CharTerm"
           " is implemented in pure Racket code except for executing "
           (code "/bin/stty")
           " for some purposes.  Specifically, "
           (code "/bin/stty")
           " at startup time and shutdown time, to set modes, and (for terminal
types that don't seem to support a screen size report control sequence) when
getting screen size.  Besides security and stability, lower dependence on
native code might also simplify porting to host platforms that don't have those
native code facilities."))

(doc (subsection "Demo")

     (para "For a demonstration, the following command, run from a terminal, should install the "
           "CharTerm"
           " package (if not already installed), and run the demo:")

     (commandline "racket -pm neil/charterm/demo")

     (para "This demo reports what keys you pressed, while letting you edit a
text field, and while displaying a clock.  The clock is updated roughly once
per second, and is not updated during heavy keyboard input, such as when typing
fast.  The demo responds to changing terminal sizes, such as when an XTerm is
window is resized.  It also displays the determined terminal size, and some
small tests of the "
           (racket #:width)
           " argument to "
           (racket charterm-display)
           ".  Exit the demo by pressing the "
           (bold "Esc")
           " key.")

     (para "Note: Although this demo includes an editable text field, as proof
of concept, the current version of "
           "CharTerm"
           " does not provide editable text fields as reusable functionality."))

(doc (subsection "Simple Example")

     (para "Here's your first "
           "CharTerm"
           " program:")

     (RACKETBLOCK
      (UNSYNTAX (code "#lang racket/base"))

      (require (planet neil/charterm))

      (with-charterm
       (charterm-clear-screen)
       (charterm-cursor 10 5)
       (charterm-display "Hello, ")
       (charterm-bold)
       (charterm-display "you")
       (charterm-normal)
       (charterm-display ".")
       (charterm-cursor 1 1)
       (charterm-display "Press a key...")
       (let ((key (charterm-read-key)))
         (charterm-cursor 1 1)
         (charterm-clear-line)
         (printf "You pressed: ~S\r\n" key))))

     (para "Now you're living the dream of the '70s."))

(doc (section "Terminal Diversity")

     (para "Like people, few terminals are exactly the same.")

     (para "Some key (ha) terms (ha) used by "
           "CharTerm"
           " are:")

     (itemlist (item (tech "termvar")
                     " --- a string value like from the Unix-like "
                     (code "TERM")
                     " environment variable, used to determine a default "
                     (tech "protocol")
                     " and "
                     (tech "keydec")
                     ".")

               (item (tech "protocol")
                     " --- how to control the display, query for information, etc.")

               (item (tech "keydec")
                     " --- how to decode key encodings of a particular
terminal.  A keydec is constructed from one or more keysets, can produce "
                     (tech "keycode")
                     "s or "
                     (tech "keyinfo")
                     "s.")

               (item (tech "keyset")
                     " --- a specification of encoding some of the keys in a
particular terminal, including "
                     (tech "keylabel")
                     "s and "
                     (tech "keycode")
                     "s.")

               (item (tech "keylabel")
                     " --- a string for how a key is likely labeled on a
keyboard, such as the DEC VT100 "
                     (bold "PF1")
                     " key would have a keylabel "
                     (racket "PF1")
                     " for a "
                     (tech "keycode")
                     " "
                     (racket 'f1)
                     ".")

               (item (tech "keycode")
                     " --- a value produced by a decoded key,
such as a character for normal printable keys, like "
                     (racket #\a)
                     " and "
                     (racket #\space)
                     ", a symbol for some recognized unprintable keys, like "
                     (racket 'escape)
                     " and "
                     (racket 'f1)
                     ", or possibly a number for unrecognized keys.")

               (item (tech "keyinfo")
                     " --- an object that is used like a "
                     (tech "keycode")
                     ", except
bundles together a keycode and a "
                     (tech "keylabel")
                     ", as well as alternatate keycodes and
information about how the key was decoded (e.g., from which "
                     (tech "keyset")
                     ")."))

     (para "These terms are discussed in the following subsections.")

     (para "CharTerm"
           " is developed with help of original documentation such as that
curated by Paul Williams at "
           (hyperlink "http://vt100.net/" "vt100.net")
           ", various commentary found on the Web, observed behavior with
modern software terminals like XTerm, various emulators for hardware terminals,
and sometimes original hardware terminals.  Thanks to Mark Pearrow for
contributing a TeleVideo 950, and Paul McCabe for a Wyse S50 WinTerm.")

     (para "At time of this writing, the author is looking to acquire a DEC
VT525, circa 1994, for ongoing testing.")

     (para "The author welcomes feedback on useful improvements to "
           "CharTerm"
           "'s support for terminal diversity (no pun).  If you have a terminal
that is sending an escape sequence not recognized by the demo, you can run the
demo with the "
           (Flag "n")
           " (aka "
           (DFlag "no-escape")
           ") argument to see the exact byte sequence:")

     (commandline "racket -pm- neil/charterm/demo -n")

     (para "When "
           (Flag "n")
           " is used, this will be indicated by the bottom-most scrolling line,
rather than saying ``"
           (tt "To quit, press " (bold "Esc") ".")
           "'' instead will say ``"
           (tt "There is no escape from this demo.")
           "'' You will have to kill the process through some other means."))

(doc (subsection "Protocol")

     (para "The first concept "
           "CharTerm"
           " has for distinguishing how to communicate with a terminal is what
is what is called here "
           (deftech "protocol")
           ", which concerns everything except how keyboard keys are decoded.
The following protocols are currently implemented:")

     (itemlist

      (item (deftech (code "ansi") " protocol")
            " --- Terminals approximating ["
            (tech "ANSI X3.64")
            "], which is most terminals in use today, including software ones
like XTerm.  This protocol is the emphasis of this package; the other protocols
are for unusual situations.")

      ;; (item (code "dec-vt100")
      ;;       " --- The DEC VT100 and compatibles that could be considered "
      ;;       (code "ansi")
      ;;       " except don't have insert-line and delete-line.")

      (item (deftech (code "wyse-wy50") " protocol")
            " --- Terminals compatible with the Wyse WY-50.  This support is
based on ["
            (tech "WY-50-QRG")
            "], ["
            (tech "WY-60-UG")
            "], ["
            (tech "wy60")
            "], and ["
            (tech "PowerTerm")
            "].  Note that video attributes are not supported, due to the WY-50's
model of having video attribute changes occupy character cells; you may wish
to run the Wyse terminal in an ANSI or VT100 mode.")

      (item (deftech (code "televideo-925") " protocol")
            " --- Terminals compatible with the TeleVideo 925.  This support is based on ["
            (tech "TVI-925-IUG")
            "] and behavior of ["
            (tech "PowerTerm")
            "].  Note that video attributes are not supported, due to the 925's
model of having video attribute changes occupy character cells; you may wish to
run your TeleVideo terminal in ANSI or VT100 mode, if it has one.")

      (item (deftech (code "ascii") " protocol")
            " --- Terminals that support ASCII but not much else that we know about.")))

(define-syntax (%charterm:protocol-case stx)
  (syntax-case stx (else)
    ((_ ERROR-NAME ACTUAL-PROTO (PART0 PART1 PARTn ...) ...)
     (let loop-clauses ((clause-stxes             (syntax->list #'((PART0 PART1 PARTn ...) ...)))
                        (reverse-out-clause-stxes '())
                        (else-stx                 #f)
                        (need-protos-hash         (make-immutable-hasheq (map (lambda (proto)
                                                                                (cons proto #t))
                                                                              '(ansi
                                                                                televideo-925
                                                                                wyse-wy50)))))
       (if (null? clause-stxes)
           (let ((missing-protos (hash-keys need-protos-hash)))
             (if (or else-stx (null? missing-protos))
                 (quasisyntax/loc stx
                   (let ((actual-proto ACTUAL-PROTO))
                     (case actual-proto
                       #,@(reverse reverse-out-clause-stxes)
                       #,(or else-stx
                             (syntax/loc stx
                               (else (error ERROR-NAME
                                            "unimplemented for protocol: ~S"
                                            actual-proto)))))))
                 (raise-syntax-error '%charterm:protocol-case
                                     (format "missing protocols ~S" missing-protos)
                                     stx)))
           (let* ((clause-stx   (car clause-stxes))
                  (clause-parts (syntax->list clause-stx))
                  (part0-stx    (car clause-parts))
                  (part0-e      (syntax-e part0-stx)))
             (if (eq? 'else part0-e)
                 (if else-stx
                     (raise-syntax-error '%charterm:protocol-case
                                         "else clause multiply defined"
                                         clause-stx
                                         #f
                                         (list else-stx))
                     (loop-clauses (cdr clause-stxes)
                                   reverse-out-clause-stxes
                                   clause-stx
                                   need-protos-hash))
                 (let loop-protos ((proto-stxes      (syntax->list (car (syntax->list clause-stx))))
                                   (need-protos-hash need-protos-hash))
                   (if (null? proto-stxes)
                       (loop-clauses (cdr clause-stxes)
                                     (cons clause-stx reverse-out-clause-stxes)
                                     else-stx
                                     need-protos-hash)
                       (let* ((proto-stx (car proto-stxes))
                              (proto-e   (syntax-e proto-stx)))
                         (if (symbol? proto-e)
                             (if (hash-has-key? need-protos-hash proto-e)
                                 (loop-protos (cdr proto-stxes)
                                              (hash-remove need-protos-hash proto-e))
                                 (raise-syntax-error '%charterm:protocol-case
                                                     "protocol unrecognized or multiply defined"
                                                     proto-stx))
                             (raise-syntax-error '%charterm:protocol-case
                                                 "invalid protocol symbol"
                                                 proto-stx))))))))))))

(define-syntax (%charterm:unimplemented stx)
  (syntax-case stx ()
    ((_ CT ERROR-NAME)
     (syntax/loc stx
       (error ERROR-NAME
              "unimplemented feature for protocol ~S"
              (charterm-protocol CT))))))

(doc (subsection "Key Encoding")

     (para "While most video display control, they seem to vary more by key
encoding.")

     (para "The "
           "CharTerm"
           " author was motivated to increase the sophistication of its
keyboard handling after a series of revelations on the Sunday of the long
weekend in which "
           "CharTerm"
           " was initially written.  The first was discovering that four of the
function keys that had been working fine in "
           (code "rxvt")
           " did not work in XTerm.  Dave Gilbert somewhat demystified this by
pointing out that the original VT100 had only four function keys, which set
into motion an unfortunate series of bad decisions by various developers of
terminal software to be needlessly incompatible with each other.  After
Googling, a horrifying 2005 Web post by Phil Gregory ["
           (tech "Gregory")
           "], which showed that key encoding among XTerm variants was even
worse than one could ever fear.  Even if one already knew how much subtleties
of old terminals varied (e.g., auto-newline behavior, whether an attribute
change consumed a space, etc.), this incompatibility in newer software was
surprising. Then, on a hunch, I tried the Linux Console on a Debian Squeeze
machine, which surely is ANSI, and found, however, that it generated "
           (italic "yet different")
           " byte sequences, for the first "
           (italic "five")
           " (not four) function keys.  Then I compared all to the ["
           (tech "ECMA-48")
           "] standard, which turns out to be nigh-inscrutable, so which might
help explain why everyone became so anti-social.")

     (para "CharTerm"
           " now provides the abstractions of "
           (tech "keysets")
           " and "
           (tech "keydecs")
           " to deal with this diversity in a maintainable way."))

(doc (subsubsection "Keylabel")

     (para "A "
           (deftech "keylabel")
           " is a Racket string for how a key is likely labeled on a particular terminal's keyboard.  Different keyboards may have different keylabels for the same "
           (tech "keycode")
           ".  For example, a VT100 has a "
           (bold "PF1")
           " key (keylabel "
           (racket "PF1")
           ", keycode "
           (racket 'f1)
           "), while many other keyboards would label the key "
           (bold "F1")
           " (keylabel "
           (racket "F1")
           ", keycode "
           (racket 'f1)
           ").  The keylabel currently is most useful for documenting and debugging, although it could later be used when giving instructions to the user, such as knowing whether to tell the user the "
           (bold "Return")
           " key or the "
           (bold "Enter")
           " key; the "
           (bold "Backspace")
           " or the "
           (bold "Rubout")
           " key; etc."))

(doc (subsubsection "Keycode")

     (para "A "
           (deftech "keycode")
           " is a value representing a key read from a terminal, which can be a Racket character, symbol, or number.  Keys corresponding to printable characters have keycodes as Racket characters.  Some keys corresponding to special non-printable characters can have keycodes of Racket symbols, such as "
           (racket 'return)
           ", "
           (racket 'f1)
           ", "
           (racket 'up)
           ", etc."))

;; TODO: Document here all the symbol keycodes we define.

(doc (defproc (charterm-keycode? (x any/c))
         boolean?
       "Predicate for whether or not "
       (racket x)
       " is a valid keycode."))
(provide charterm-keycode?)
(define (charterm-keycode? x)
  (if (or (symbol? x)
          (char? x)
          (exact-nonnegative-integer? x))
      #t
      #f))

(doc (subsubsection "Keyinfo")

     (para "A "
           (deftech "keyinfo")
           " represents a "
           (tech "keycode")
           " for a key, a "
           (tech "keylabel")
           ", and how it is encoded as bytes.  It is represented in Racket as
a "
           (racket charterm-keyinfo)
           " object."))

(define-struct charterm-keyinfo
  (keyset-id
   bytelang
   bytelist
   keylabel
   keycode
   all-keycodes)
  #:transparent)

(doc (defproc (charterm-keyinfo? (x any/c))
         boolean?)
     "Predicate for whether or not "
     (racket x)
     " is a "
     (racket charterm-keyinfo)
     " object.")
(provide charterm-keyinfo?)

(doc (defproc*
         (((charterm-keyinfo-keyset-id    (ki charterm-keyinfo?)) symbol?)
          ((charterm-keyinfo-bytelang     (ki charterm-keyinfo?)) string?)
          ((charterm-keyinfo-bytelist     (ki charterm-keyinfo?)) (listof byte?))
          ((charterm-keyinfo-keylabel     (ki charterm-keyinfo?)) string?)
          ((charterm-keyinfo-keycode      (ki charterm-keyinfo?)) charterm-keycode?)
          ((charterm-keyinfo-all-keycodes (ki charterm-keyinfo?)) (listof charterm-keycode?)))
       (para "Get information from a "
             (racket charterm-keyinfo)
             " object.")))
(provide charterm-keyinfo-keyset-id
         charterm-keyinfo-bytelang
         charterm-keyinfo-bytelist
         charterm-keyinfo-keylabel
         charterm-keyinfo-keycode
         charterm-keyinfo-all-keycodes)

(define %charterm:bytestr-to-byte-hash
  (make-hash
   `(("nul"      . 0)
     ("null"     . 0)
     ("lf"       . 10)
     ("linefeed" . 10)
     ("cr"       . 13)
     ("return"   . 13)
     ("ret"      . 13)
     ("esc"      . 27)
     ("^["       . 27)
     ("sp"       . 32)
     ("space"    . 32)
     ,@(for/list ((n (in-range 1 26)))
         (cons (string #\^ (integer->char (+ 96 n)))
               n))
     ,@(for/list ((n (in-range 1 26)))
         (cons (string-append "ctrl-"
                              (string (integer->char (+ 96 n))))
               n))
     ,@(for/list ((n (in-range 32 127)))
         (cons (string (integer->char n))
               n))
     ,@(for/list ((n (in-range 0 255)))
         (cons (string-append "("
                              (number->string n)
                              ")")
               n)))))

(define (%charterm:bytestr->byte bytestr)
  (hash-ref %charterm:bytestr-to-byte-hash bytestr))

(define (%charterm:bytelang->bytelist bytelang secondary?)
  (let ((bytelist (map %charterm:bytestr->byte
                       (regexp-split #rx" +" bytelang))))
    (if (and secondary? (not (= 1 (length bytelist))))
        (error '%charterm:bytelang->bytelist
               "bytelist for secondary keyset: ~S"
               bytelist)
        bytelist)))

(define (%charterm:keycode->keylabel keycode)
  (cond ((not keycode) #f)
        ((symbol? keycode) (string-titlecase (symbol->string keycode)))
        ((char?   keycode) (string keycode))
        ((number? keycode) (number->string keycode))
        (else (error '%charterm:keycode->keylabel
                     "invalid keycode: ~S"
                     keycode))))

(define (%charterm:keylang->keyinfo keyset-id keylang secondary?)
  (apply (lambda (bytelang . args)
           (let-values (((bytelist)
                         (%charterm:bytelang->bytelist bytelang secondary?))
                        ((keylabel keycode all-keycodes)
                         (let ((keylabel (car args)))
                           (if (or (string? keylabel)
                                   (not keylabel))
                               (values keylabel
                                       (cadr args)
                                       (cdr args))
                               (let ((keycode (car args)))
                                 (values (%charterm:keycode->keylabel keycode)
                                         keycode
                                         args))))))
             (make-charterm-keyinfo keyset-id
                                    bytelang
                                    bytelist
                                    keylabel
                                    keycode
                                    all-keycodes)))
         keylang))

(doc (subsubsection "Keyset")

     (para "A "
           (deftech "keyset")
           " is a specification of keys on a particular keyboard, including their "
           (tech "keylabel")
           ", encoding as bytes, and primary and alternate "
           (tech #:key "keycode" "keycodes")
           ".")

     ;; TODO: Expose ability to construct keysets, once it's finalized.
     (para "The means of constructing a keyset is currently internal to this package."))

(define-struct charterm-keyset
  (id primary-keyinfos secondary-keyinfos)
  #:transparent)

(doc (defproc (charterm-keyset? (x any/c))
         boolean?
       (para "Predicate for whether or not "
             (racket x)
             " is a keyset.")))
(provide charterm-keyset?)

(doc (defproc (charterm-keyset-id (ks charterm-keyset?))
         symbol?)
     (para "Get a symbol identifying the keyset."))
(provide charterm-keyset-id)

;; (define (%charterm:keyinfos? x)
;;   (for/and ((x (in-list x)))
;;     (charterm-keyinfo? x)))
;;
;; (define (%charterm:assert-keyinfos keyinfos)
;;   (or (%charterm:keyinfos? keyinfos)
;;       (error '%charterm:assert-keyinfos
;;              "assertion failed: ~S"
;;              keyinfos)))

(define (make-charterm-keyset-from-keylangs keyset-id
                                            keylangs
                                            (secondary-keylangs '()))
  (let ((primary-keyinfos   (map (lambda (keylang)
                                   (%charterm:keylang->keyinfo keyset-id keylang #f))
                                 keylangs))
        (secondary-keyinfos (map (lambda (keylang)
                                   (%charterm:keylang->keyinfo keyset-id keylang #t))
                                 secondary-keylangs)))
    ;; (%charterm:assert-keyinfos primary-keyinfos)
    ;; (%charterm:assert-keyinfos secondary-keyinfos)
    (charterm-keyset keyset-id
                     primary-keyinfos
                     secondary-keyinfos)))

(doc (defthing charterm-ascii-keyset charterm-keyset?
       (para "From the old ["
             (tech "ASCII")
             "] standard.  When defining a "
             (tech "keydec")
             ", this is good to have as a final keyset, after the others.")))
(define charterm-ascii-keyset
  (let ((keylangs
         `(("(0)"   "NUL"       nul             null)
           ("(1)"   "Ctrl-A"    ctrl-a          start-of-heading soh)
           ("(2)"   "Ctrl-B"    ctrl-b          start-of-text stx)
           ("(3)"   "Ctrl-C"    ctrl-c          end-of-text etx)
           ("(4)"   "Ctrl-D"    ctrl-d          end-of-transmission eot)
           ("(5)"   "Ctrl-E"    ctrl-e          enquiry enq)
           ("(6)"   "Ctrl-F"    ctrl-f          acknowledge ack)
           ("(7)"   "Ctrl-G"    ctrl-g          bell bel)
           ("(8)"   "Backspace" backspace       ctrl-h bs)
           ("(9)"   "Tab"       tab             ctrl-i horizontal-tab ht)
           ("(10)"  "Linefeed"  linefeed        ctrl-j line-feed lf)
           ("(11)"  "Ctrl-K"    ctrl-k          vertical-tab vt)
           ("(12)"  "Ctrl-L"    ctrl-l          formfeed form-feed ff)
           ("(13)"  "Return"    return          ctrl-m carriage-return cr)
           ("(14)"  "Ctrl-N"    ctrl-n          shift-out so)
           ("(15)"  "Ctrl-O"    ctrl-o          shift-in si)
           ("(16)"  "Ctrl-P"    ctrl-p          data-link-escape dle)
           ("(17)"  "Ctrl-Q"    ctrl-q          device-control-1 dc1)
           ("(18)"  "Ctrl-R"    ctrl-r          device-control-2 dc2)
           ("(19)"  "Ctrl-S"    ctrl-s          device-control-3 dc3)
           ("(20)"  "Ctrl-T"    ctrl-t          device-control-4 dc4)
           ("(21)"  "Ctrl-U"    ctrl-u          negative-acknowledgement nak)
           ("(22)"  "Ctrl-V"    ctrl-v          synchronous-idle syn)
           ("(23)"  "Ctrl-W"    ctrl-w          end-of-transmission-block etb)
           ("(24)"  "Ctrl-X"    ctrl-x          cancel can)
           ("(25)"  "Ctrl-Y"    ctrl-y          end-of-medium em)
           ("(26)"  "Ctrl-Z"    ctrl-z          substitute sub)
           ("(27)"  "Esc"       escape          esc)
           ("(28)"  "FS"        file-separator  fs)
           ("(29)"  "GS"        group-separator gs)
           ("(30)"  "RS"        record-separtor rs)
           ("(31)"  "US"        unit-separator  us)
           ("(32)"  "Space"     #\space         space sp)
           ("(127)" "Delete"    delete          del)
           ,@(for/list ((n (in-range 32 127)))
               (let ((c (integer->char n)))
                 (list (string-append "(" (number->string n) ")")
                       (string c)
                       c))))))
    (make-charterm-keyset-from-keylangs
     'ascii
     keylangs
     keylangs)))

(doc (defthing charterm-dec-vt100-keyset charterm-keyset?
       (para "From the DEC VT100.  This currently defines the four function
keys (labeled on the keyboard, "
             (bold "PF1")
             " through "
             (bold "PF4")
             ") as "
             (racket 'f1)
             " through "
             (racket 'f4)
             ", and the arrow keys.  ["
             (tech "VT100-UG")
             "] and ["
             (tech "PowerTerm")
             "] were used as references.")))
(provide charterm-dec-vt100-keyset)
(define  charterm-dec-vt100-keyset
  (make-charterm-keyset-from-keylangs
   'dec-vt100
   '(("esc O P" "PF1" f1)
     ("esc O Q" "PF2" f2)
     ("esc O R" "PF3" f3)
     ("esc O S" "PF4" f4)

     ("esc [ A" up)
     ("esc [ B" down)
     ("esc [ C" right)
     ("esc [ D" left)
     
     ;; Note: PowerTerm does not map PC key F1 like VT100, etc.  It maps all
     ;; the PC F keys to other sequences that are like the VT220.
     )))

(doc (defthing charterm-dec-vt220-keyset charterm-keyset?
       (para "From the DEC VT220.  This currently defines function keys "
             (bold "F1")
             " through "
             (bold "F20")
             ".")))
(provide charterm-dec-vt220-keyset)
(define  charterm-dec-vt220-keyset
  (make-charterm-keyset-from-keylangs
   'dec-vt220
   '(
     ("esc [ 1 1 ~" f1)
     ("esc [ 1 2 ~" f2)
     ("esc [ 1 3 ~" f3)
     ("esc [ 1 4 ~" f4)
     ("esc [ 1 5 ~" f5)
     ("esc [ 1 7 ~" f6)
     ("esc [ 1 8 ~" f7)
     ("esc [ 1 9 ~" f8)
     ("esc [ 2 0 ~" f9)
     ("esc [ 2 1 ~" f10)
     ("esc [ 2 3 ~" f11)
     ("esc [ 2 4 ~" f12)
     ("esc [ 2 5 ~" f13)
     ("esc [ 2 6 ~" f14)
     ("esc [ 2 8 ~" f15)
     ("esc [ 2 9 ~" f16)
     ("esc [ 3 1 ~" f17)
     ("esc [ 3 2 ~" f18)
     ("esc [ 3 3 ~" f19)
     ("esc [ 3 4 ~" f20)

     ;; TODO: Make the keylang expand to both "esc [" and "(155)" CSI or
     ;; whatever.
     
     ("(155) 1 1 ~" f1)
     ("(155) 1 2 ~" f2)
     ("(155) 1 3 ~" f3)
     ("(155) 1 4 ~" f4)
     ("(155) 1 5 ~" f5)
     ("(155) 1 7 ~" f6)
     ("(155) 1 8 ~" f7)
     ("(155) 1 9 ~" f8)
     ("(155) 2 0 ~" f9)
     ("(155) 2 1 ~" f10)
     ("(155) 2 3 ~" f11)
     ("(155) 2 4 ~" f12)
     ("(155) 2 5 ~" f13)
     ("(155) 2 6 ~" f14)
     ("(155) 2 8 ~" f15)
     ("(155) 2 9 ~" f16)
     ("(155) 3 1 ~" f17)
     ("(155) 3 2 ~" f18)
     ("(155) 3 3 ~" f19)
     ("(155) 3 4 ~" f20)

     )))

(doc (defthing charterm-screen-keyset charterm-keyset?
       (para "From the "
             (hyperlink "http://en.wikipedia.org/wiki/GNU_Screen"
                        "GNU Screen")
             " terminal multiplexer, according to ["
             (tech "Gregory")
             "].  Also used by "
             (hyperlink "http://en.wikipedia.org/wiki/Tmux"
                        (code "tmux"))
             ".")))
(provide charterm-screen-keyset)
(define  charterm-screen-keyset
  (make-charterm-keyset-from-keylangs
   'screen
   '(("esc O P"     f1)
     ("esc O Q"     f2)
     ("esc O R"     f3)
     ("esc O S"     f4)
     ("esc [ 1 5 ~" f5)
     ("esc [ 1 7 ~" f6)
     ("esc [ 1 8 ~" f7)
     ("esc [ 1 9 ~" f8)
     ("esc [ 2 0 ~" f9)
     ("esc [ 2 1 ~" f10)
     ("esc [ 2 3 ~" f11)
     ("esc [ 2 4 ~" f12)

     ("esc [ 3 ~" "Delete" delete del)
     ("esc [ 7 ~" "Home" home)
     ("esc [ 8 ~" "End"  end)
     
     ("(127)" "Backspace" backspace)
     )))

(doc (defthing charterm-linux-keyset charterm-keyset?
       (para "From the Linux console.  Currently defines function keys "
             (bold "F1")
             " through "
             (bold "F5")
             " only, since the rest will be inherited from other keysets.")))
(provide charterm-linux-keyset)
(define charterm-linux-keyset
  (make-charterm-keyset-from-keylangs
   'linux
   '(("esc [ [ A" f1)
     ("esc [ [ B" f2)
     ("esc [ [ C" f3)
     ("esc [ [ D" f4)
     ("esc [ [ E" f5))))

(doc (defthing charterm-xterm-x11r6-keyset charterm-keyset?
       (para "From the XTerm in X11R6, according to ["
             (tech "Gregory")
             "].")))
(provide charterm-xterm-x11r6-keyset)
(define  charterm-xterm-x11r6-keyset
  (make-charterm-keyset-from-keylangs
   'xterm-x11r6
   '(("esc [ 1 1 ~"     f1)
     ("esc [ 1 2 ~"     f2)
     ("esc [ 1 3 ~"     f3)
     ("esc [ 1 4 ~"     f4)
     ("esc [ 1 5 ~"     f5)
     ("esc [ 1 7 ~"     f6)
     ("esc [ 1 8 ~"     f7)
     ("esc [ 1 9 ~"     f8)
     ("esc [ 2 0 ~"     f9)
     ("esc [ 2 1 ~"     f10)
     ("esc [ 2 3 ~"     f11)
     ("esc [ 2 4 ~"     f12)
     ("esc [ 1 1 ; 2 ~" f13)
     ("esc [ 1 2 ; 2 ~" f14)
     ("esc [ 1 3 ; 2 ~" f15)
     ("esc [ 1 4 ; 2 ~" f16)
     ("esc [ 1 5 ; 2 ~" f17)
     ("esc [ 1 7 ; 2 ~" f18)
     ("esc [ 1 8 ; 2 ~" f19)
     ("esc [ 1 9 ; 2 ~" f20)
     ("esc [ 2 0 ; 2 ~" f21)
     ("esc [ 2 1 ; 2 ~" f22)
     ("esc [ 2 3 ; 2 ~" f23)
     ("esc [ 2 4 ; 2 ~" f24)
     ("esc [ 1 1 ; 5 ~" f25)
     ("esc [ 1 2 ; 5 ~" f26)
     ("esc [ 1 3 ; 5 ~" f27)
     ("esc [ 1 4 ; 5 ~" f28)
     ("esc [ 1 5 ; 5 ~" f29)
     ("esc [ 1 7 ; 5 ~" f30)
     ("esc [ 1 8 ; 5 ~" f31)
     ("esc [ 1 9 ; 5 ~" f32)
     ("esc [ 2 0 ; 5 ~" f33)
     ("esc [ 2 1 ; 5 ~" f34)
     ("esc [ 2 3 ; 5 ~" f35)
     ("esc [ 2 4 ; 5 ~" f36)
     ("esc [ 1 1 ; 6 ~" f37)
     ("esc [ 1 2 ; 6 ~" f38)
     ("esc [ 1 3 ; 6 ~" f39)
     ("esc [ 1 4 ; 6 ~" f40)
     ("esc [ 1 5 ; 6 ~" f41)
     ("esc [ 1 7 ; 6 ~" f42)
     ("esc [ 1 8 ; 6 ~" f43)
     ("esc [ 1 9 ; 6 ~" f44)
     ("esc [ 2 0 ; 6 ~" f45)
     ("esc [ 2 1 ; 6 ~" f46)
     ("esc [ 2 3 ; 6 ~" f47)
     ("esc [ 2 4 ; 6 ~" f48))))

(doc (defthing charterm-xterm-xfree86-keyset charterm-keyset?
       (para "From the XFree86 XTerm, according to ["
             (tech "Gregory")
             "].")))
(provide charterm-xterm-xfree86-keyset)
(define  charterm-xterm-xfree86-keyset
  (make-charterm-keyset-from-keylangs
   'xterm-xfree86
   '(("esc O P"         f1)
     ("esc O Q"         f2)
     ("esc O R"         f3)
     ("esc O S"         f4)
     ("esc [ 1 5 ~"     f5)
     ("esc [ 1 7 ~"     f6)
     ("esc [ 1 8 ~"     f7)
     ("esc [ 1 9 ~"     f8)
     ("esc [ 2 0 ~"     f9)
     ("esc [ 2 1 ~"     f10)
     ("esc [ 2 3 ~"     f11)
     ("esc [ 2 4 ~"     f12)
     ("esc O 2 P"       f13)
     ("esc O 2 Q"       f14)
     ("esc O 2 R"       f15)
     ("esc O 2 S"       f16)
     ("esc [ 1 5 ; 2 ~" f17)
     ("esc [ 1 7 ; 2 ~" f18)
     ("esc [ 1 8 ; 2 ~" f19)
     ("esc [ 1 9 ; 2 ~" f20)
     ("esc [ 2 0 ; 2 ~" f21)
     ("esc [ 2 1 ; 2 ~" f22)
     ("esc [ 2 3 ; 2 ~" f23)
     ("esc [ 2 4 ; 2 ~" f24)
     ("esc O 5 P"       f25)
     ("esc O 5 Q"       f26)
     ("esc O 5 R"       f27)
     ("esc O 5 S"       f28)
     ("esc [ 1 5 ; 5 ~" f29)
     ("esc [ 1 7 ; 5 ~" f30)
     ("esc [ 1 8 ; 5 ~" f31)
     ("esc [ 1 9 ; 5 ~" f32)
     ("esc [ 2 0 ; 5 ~" f33)
     ("esc [ 2 1 ; 5 ~" f34)
     ("esc [ 2 3 ; 5 ~" f35)
     ("esc [ 2 4 ; 5 ~" f36)
     ("esc O 6 P"       f37)
     ("esc O 6 Q"       f38)
     ("esc O 6 R"       f39)
     ("esc O 6 S"       f40)
     ("esc [ 1 5 ; 6 ~" f41)
     ("esc [ 1 7 ; 6 ~" f42)
     ("esc [ 1 8 ; 6 ~" f43)
     ("esc [ 1 9 ; 6 ~" f44)
     ("esc [ 2 0 ; 6 ~" f45)
     ("esc [ 2 1 ; 6 ~" f46)
     ("esc [ 2 3 ; 6 ~" f47)
     ("esc [ 2 4 ; 6 ~" f48))))

(doc (defthing charterm-xterm-new-keyset charterm-keyset?
       (para "From the current "
             (code "xterm-new")
             ", often called simply "
             (code "xterm")
             ", as developed by Thomas E. Dickey, and documented in ["
             (tech "XTerm-ctlseqs")
             "].  Several also came from decompiling a "
             (code "terminfo")
             " entry.  Thanks to Dickey for his emailed help.")))
(provide charterm-xterm-new-keyset)
(define  charterm-xterm-new-keyset
  (make-charterm-keyset-from-keylangs
   'xterm-new
   '(

     ;; CSI = "esc ["
     ;; SS3 = "esc O"

     ("esc [ A" up)
     ("esc [ B" down)
     ("esc [ C" right)
     ("esc [ D" left)
     ("esc [ H" home)
     ("esc [ F" end)

     ;; The following came from decompiling an xterm terminfo
     ("esc O A" up)
     ("esc O B" down)
     ("esc O C" right)
     ("esc O D" left)
     ("esc O H" home)
     ("esc O F" end)

     ("esc O P" f1)
     ("esc O Q" f2)
     ("esc O R" f3)
     ("esc O S" f4)
     ("esc [ 1 5 ~" f5)
     ("esc [ 1 7 ~" f6)
     ("esc [ 1 8 ~" f7)
     ("esc [ 1 9 ~" f8)
     ("esc [ 2 0 ~" f9)
     ("esc [ 2 1 ~" f10)
     ("esc [ 2 3 ~" f11)
     ("esc [ 2 4 ~" f12)

     ("esc O I" tab kp-tab)
     ("esc O M" "Enter" return enter kp-return kp-enter)
     ("esc O P" "PF1" f1 kp-f1)
     ("esc O Q" "PF2" f2 kp-f2)
     ("esc O R" "PF3" f3 kp-f3)
     ("esc O S" "PF4" f4 kp-f4)
     ("esc [ 3 ~" "Delete" delete del kp-delete)
     ("esc [ 2 ~" "Insert" insert ins kp-insert)
     ("esc O F"   "End" end kp-end)
     ("esc [ B" "Down" down kp-down)
     ("esc [ 6 ~" "PgDn" pgdn kp-pgdn)
     ("esc [ D" "Left" left kp-left)
     ("esc [ E" "Begin" begin kp-begin)
     ("esc [ C" "Right" right kp-right)
     ("esc O H" "Home" home kp-home)
     ("esc [ A" "Up" up kp-up)
     ("esc [ 5 ~" "PgUp" pgup kp-pgup)

     ("esc [ 1 1 ~" "F1" f1)
     ("esc [ 1 2 ~" "F2" f2)
     ("esc [ 1 3 ~" "F3" f3)
     ("esc [ 1 4 ~" "F4" f4)

     ;; TODO: continue working on this from dickey's xterm control sequences doc

     )))

(doc (defthing charterm-rxvt-keyset charterm-keyset?
       (para "From the "
             (hyperlink "http://en.wikipedia.org/wiki/Rxvt"
                        (code "rxvt"))
             " terminal emulator.  These come from ["
             (tech "Gregory")
             "], and
currently define function keys "
             (racket 'f1)
             " through "
             (racket 'f44)
             ".")))
(define charterm-rxvt-keyset
  (make-charterm-keyset-from-keylangs
   'rxvt
   '(("esc [ 1 1 ~" f1)
     ("esc [ 1 2 ~" f2)
     ("esc [ 1 3 ~" f3)
     ("esc [ 1 4 ~" f4)
     ("esc [ 1 5 ~" f5)
     ("esc [ 1 7 ~" f6)
     ("esc [ 1 8 ~" f7)
     ("esc [ 1 9 ~" f8)
     ("esc [ 2 0 ~" f9)
     ("esc [ 2 1 ~" f10)
     ("esc [ 2 3 ~" shift-f1  f11) ;; TODO: These shift- and ctrl- are actually from termvar xterm in an rxvt
     ("esc [ 2 4 ~" shift-f2  f12)
     ("esc [ 2 5 ~" shift-f3  f13)
     ("esc [ 2 6 ~" shift-f4  f14)
     ("esc [ 2 8 ~" shift-f5  f15)
     ("esc [ 2 9 ~" shift-f6  f16)
     ("esc [ 3 1 ~" shift-f7  f17)
     ("esc [ 3 2 ~" shift-f8  f18)
     ("esc [ 3 3 ~" shift-f9  f19)
     ("esc [ 3 4 ~" shift-f10 f20)
     ("esc [ 2 3 $" shift-f11 f21)
     ("esc [ 2 4 $" shift-f12 f22)
     ("esc [ 1 1 ^" ctrl-f1   f23)
     ("esc [ 1 2 ^" ctrl-f2   f24)
     ("esc [ 1 3 ^" ctrl-f3   f25)
     ("esc [ 1 4 ^" ctrl-f4   f26)
     ("esc [ 1 5 ^" ctrl-f5   f27)
     ("esc [ 1 7 ^" ctrl-f6   f28)
     ("esc [ 1 8 ^" ctrl-f7   f29)
     ("esc [ 1 9 ^" ctrl-f8   f30)
     ("esc [ 2 0 ^" ctrl-f9   f31)
     ("esc [ 2 1 ^" ctrl-f10  f32)
     ("esc [ 2 3 ^" ctrl-f11  f33)
     ("esc [ 2 4 ^" ctrl-f12  f34)
     ("esc [ 2 5 ^" f35)
     ("esc [ 2 6 ^" f36)
     ("esc [ 2 8 ^" f37)
     ("esc [ 2 9 ^" f38)
     ("esc [ 3 1 ^" f39)
     ("esc [ 3 2 ^" f40)
     ("esc [ 3 3 ^" f41)
     ("esc [ 3 4 ^" f42)
     ("esc [ 2 3 @" f43)
     ("esc [ 2 4 @" f44)
     ("(127)" "Backspace" backspace) ; Override one from "ascii" keyset.
     ;; TODO: actually, these arrow keys were observed in rxvt with termvar xterm.  which keyset should they be in?
     ("esc [ A"     "Up" up)
     ("esc [ B"     "Down" down)
     ("esc [ C"     "Right" right)
     ("esc [ D"     "Left" left)
     ("esc [ 5 ~"   "PgUp" pgup page-up)
     ("esc [ 6 ~"   "PgDn" pgdn page-down)
     ("esc [ 7 ~"   "Home" home)
     ("esc [ 8 ~"   "End"  end)
     ("esc [ 3 ~"   "Delete" delete del)
     ("esc [ 2 ~"   "Insert" insert ins)
     )))

(doc (defthing charterm-wyse-wy50-keyset charterm-keyset?
       (para "From the Wyse WY-50, based on ["
             (tech "WY-50-QRG")
             "] and looking at photos of WY-50 keyboard, and tested in ["
             (tech "wy60")
             "] and ["
             (tech "PowerTerm")
             "].  The shifted function keys are provided as both "
             (racket 'shift-f1)
             " through "
             (racket 'shift-16)
             ", and "
             (racket 'f17)
             " through "
             (racket 'f31)
             ".")))
(provide charterm-wyse-wy50-keyset)
(define  charterm-wyse-wy50-keyset
  (make-charterm-keyset-from-keylangs
   'wyse-wy50
   '(("^a @ cr"  f1)
     ("^a A cr"  f2)
     ("^a B cr"  f3)
     ("^a C cr"  f4)
     ("^a D cr"  f5)
     ("^a E cr"  f6)
     ("^a F cr"  f7)
     ("^a G cr"  f8)
     ("^a H cr"  f9)
     ("^a I cr"  f10)
     ("^a J cr"  f11)
     ("^a K cr"  f12)
     ("^a L cr"  f13)
     ("^a M cr"  f14)
     ("^a N cr"  f15)
     ("^a O cr"  f16)
     ("^a ` cr"  "Shift-F1" shift-f1 f17)
     ("^a a cr"  "Shift-F2" shift-f2 f18)
     ("^a b cr"  "Shift-F3" shift-f3 f19)
     ("^a c cr"  "Shift-F4" shift-f4 f20)
     ("^a d cr"  "Shift-F5" shift-f5 f21)
     ("^a e cr"  "Shift-F6" shift-f6 f22)
     ("^a f cr"  "Shift-F7" shift-f7 f23)
     ("^a g cr"  "Shift-F8" shift-f8 f24)
     ("^a h cr"  "Shift-F9" shift-f9 f25)
     ("^a i cr"  "Shift-F10" shift-f10 f26)
     ("^a j cr"  "Shift-F11" shift-f11 f27)
     ("^a k cr"  "Shift-F12" shift-f12 f28)
     ("^a l cr"  "Shift-F13" shift-f13 f29)
     ("^a m cr"  "Shift-F14" shift-f14 f30)
     ("^a n cr"  "Shift-F15" shift-f15 f31)
     ("^a o cr"  "Shift-F16" shift-f16 f32)
     ("ctrl-h"   "Left" left)
     ("linefeed" "Down" down)
     ("(11)"     "Up" up)
     ("(12)"     "Right" right)
     ("esc W"    "DEL Char" delete)
     ("esc Q"    "INS Char" insert-char)
     ("esc q"    "Ins" insert ins)
     ("esc T"    "CLR Line" clear-line)
     ("esc r"    "Repl" repl)
     ("esc R"    "DEL Line" delete-line)
     ("esc J"    "PAGE Prev" pgup page-up)
     ("esc K"    "PAGE Next" pgdn page-down)
     ("esc P"    "Print" print)
     ("esc Y"    "CLR Screen" clear-screen)
     ("(30)"     "Home" home record-separator rs)
     ("(13)"     "Return" return)
     ("(127)"    "Shift-Backspace" backspace shift-backspace)
     )))

(doc (defthing charterm-televideo-925-keyset charterm-keyset?
       (para "From the TeleVideo 925, based on ["
             (tech "TVI-925-IUG")
             "], ["
             (tech "PowerTerm")
             "], and from looking at a TeleVideo 950 keyboard.")))
(provide charterm-televideo-925-keyset charterm-keyset?)
(define  charterm-televideo-925-keyset
  (make-charterm-keyset-from-keylangs
   'televideo-925
   '(("ctrl-a @ cr" f1)
     ("ctrl-a A cr" f2)
     ("ctrl-a B cr" f3)
     ("ctrl-a C cr" f4)
     ("ctrl-a D cr" f5)
     ("ctrl-a E cr" f6)
     ("ctrl-a F cr" f7)
     ("ctrl-a G cr" f8)
     ("ctrl-a H cr" f9)
     ("ctrl-a I cr" f10)
     ("ctrl-a J cr" f11)

     ("ctrl-a \\ cr" "SHIFT-F1" shift-f1)
     ("ctrl-a a cr" "SHIFT-F2" shift-f2)
     ("ctrl-a b cr" "SHIFT-F3" shift-f3)
     ("ctrl-a c cr" "SHIFT-F4" shift-f4)
     ("ctrl-a d cr" "SHIFT-F5" shift-f5)
     ("ctrl-a e cr" "SHIFT-F6" shift-f6)
     ("ctrl-a f cr" "SHIFT-F7" shift-f7)
     ("ctrl-a g cr" "SHIFT-F8" shift-f8)
     ("ctrl-a h cr" "SHIFT-F9" shift-f9)
     ("ctrl-a i cr" "SHIFT-F10" shift-f10)
     ("ctrl-a j cr" "SHIFT-F11" shift-f11)

     ("ctrl-k" "Up" up ctrl-k)
     ("ctrl-v" "Down" down ctrl-v)
     ("ctrl-h" "Left" left ctrl-h)
     ("ctrl-l" "Right" right ctrl-l)

     ("esc W" "CHAR DELETE" delete del char-delete)

     ("esc Q" "CHAR INSERT" insert ins char-insert)

     ("esc j" "Reverse Linefeed" reverse-linefeed reverse-lf reverse-line-feed)

     ("esc i" "BACK TAB" backtab back-tab)
     ("ctrl-m" "RETURN" return ctrl-m)
     ("ctrl-j" "LINEFEED" linefeed lf ctrl-j)
     ("(127)" "DEL" delete del)
     ;; ("esc Q" "CHAR INSERT" char-insert char-ins)

     )))

(doc (subsubsection "Keydec")

     (para "A "
           (deftech "keydec")
           " object is a key decoder for a specific variety of terminal, such
as for a specific "
           (tech "termvar")
           ".  A keydec is used to turn received key encodings from a terminal into "
           (tech "keycode")
           " or "
           (tech "keyinfo")
           " values.  A keydec is constructed from a prioritized list of "
           (tech "keyset")
           " objects, with earlier-listed keysets taking priority of
later-listed keysets when there is conflict between them as to how to decode a
particular byte sequence."))

(define (%charterm:make-keytree (alist '()))
  (make-immutable-hasheqv alist))

(define (%charterm:keytree-add-keyinfo-if-can keytree keyinfo)
  (let ((bytelist (charterm-keyinfo-bytelist keyinfo)))
    (let loop-bytelist ((this-byte  (car bytelist))
                        (rest-bytes (cdr bytelist))
                        (node       keytree))
      (cond ((hash? node)
             (cond ((hash-ref node this-byte #f)
                    => (lambda (existing-sub-node)
                         ;; Node has a match for this byte, so do we have another
                         ;; byte and can follow it?
                         (if (null? rest-bytes)
                             ;; Node has a match for this byte, but we have no
                             ;; more bytes, so can't add.
                             node
                             ;; Node has a match for this byte, and we have more
                             ;; bytes, so follow it.
                             (hash-set node
                                       this-byte
                                       (loop-bytelist (car rest-bytes)
                                                      (cdr rest-bytes)
                                                      existing-sub-node)))))
                   (else
                    ;; Node has no match for this byte, so add new path.
                    (hash-set node
                              this-byte
                              (let loop ((rest-bytes rest-bytes))
                                (if (null? rest-bytes)
                                    keyinfo
                                    (%charterm:make-keytree
                                     (cons (cons (car rest-bytes)
                                                 (loop (cdr rest-bytes)))
                                           '()))))))))

            ((charterm-keyinfo? node)
             ;; Node is already a keyinfo, so can't add.
             node)
            (else (error
                   '%charterm:keytree-add-keyinfo-if-can
                   "invalid node ~S with this-byte ~S, rest-bytes ~S, keyinfo ~S"
                   node
                   this-byte
                   rest-bytes
                   keyinfo))))))

(define (%charterm:keytree-add-any-keyinfos-can keytree keyinfos)
  (let loop ((keyinfos keyinfos)
             (keytree  keytree))
    (if (null? keyinfos)
        keytree
        (loop (cdr keyinfos)
              (%charterm:keytree-add-keyinfo-if-can keytree
                                                    (car keyinfos))))))

(define (%charterm:make-keytree-from-keyinfoses keyinfoses)
  (let loop ((keyinfoses keyinfoses)
             (keytree (%charterm:make-keytree)))
    (if (null? keyinfoses)
        keytree
        (let ((keyinfos (car keyinfoses)))
          ;; (and (not (null? keyinfos))
          ;;      (not (charterm-keyinfo? (car keyinfos)))
          ;;      (error '%charterm:make-keytree-from-keyinfoses
          ;;             "bad keyinfos: ~S"
          ;;             keyinfos))
          (loop (cdr keyinfoses)
                (%charterm:keytree-add-any-keyinfos-can keytree
                                                        keyinfos))))))

(doc (defproc (charterm-keydec-id (kd charterm-keydec?))
         symbol?
       (para "Gets the ID symbol of the "
             (tech "keydec")
             " being used.")))
(provide charterm-keydec-id)

(struct charterm-keydec
  (id
   primary-keytree
   secondary-keytree)
  #:transparent)

(define (charterm-make-keydec keydec-id . keysets)
  (charterm-keydec keydec-id
                   (%charterm:make-keytree-from-keyinfoses
                    (map charterm-keyset-primary-keyinfos keysets))
                   (%charterm:make-keytree-from-keyinfoses
                    (map charterm-keyset-secondary-keyinfos keysets))))

(doc (subsubsub*section "ANSI Keydecs"))

(doc (defthing charterm-vt100-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "vt100")
             ".")))
(provide charterm-vt100-keydec)
(define  charterm-vt100-keydec
  (charterm-make-keydec 'vt100
                        charterm-dec-vt100-keyset
                        charterm-dec-vt220-keyset
                        charterm-xterm-new-keyset
                        charterm-linux-keyset
                        charterm-rxvt-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-vt220-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "vt220")
             ".")))
(provide charterm-vt220-keydec)
(define  charterm-vt220-keydec
  (charterm-make-keydec 'vt220
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-screen-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "screen")
             ".")))
(provide charterm-screen-keydec)
(define  charterm-screen-keydec
  (charterm-make-keydec 'screen
                        charterm-screen-keyset
                        charterm-linux-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-xterm-new-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-linux-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "linux")
             ".")))
(provide charterm-linux-keydec)
(define  charterm-linux-keydec
  (charterm-make-keydec 'linux
                        charterm-linux-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-xterm-new-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-screen-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-xterm-new-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "xterm-new")
             ".")))
(provide charterm-xterm-new-keydec)
(define  charterm-xterm-new-keydec
  (charterm-make-keydec 'xterm-new
                        charterm-xterm-new-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-rxvt-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-linux-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-xterm-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "xterm")
             ".  Currently same as the keydec for "
             (code "xterm")
             ", except for a different ID.")))
(provide charterm-xterm-keydec)
(define  charterm-xterm-keydec
  (charterm-make-keydec 'xterm
                        charterm-xterm-new-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-rxvt-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-linux-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-rxvt-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "rxvt")
             ".")))
(provide charterm-rxvt-keydec)
(define  charterm-rxvt-keydec
  (charterm-make-keydec 'rxvt
                        charterm-rxvt-keyset
                        charterm-xterm-new-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-linux-keyset
                        charterm-ascii-keyset))

(doc (subsubsub*section "Wyse Keydecs"))

(doc (defthing charterm-wy50-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "wy50")
             ".")))
(provide charterm-wy50-keydec)
(define  charterm-wy50-keydec
  (charterm-make-keydec 'wy50
                        charterm-wyse-wy50-keyset
                        charterm-ascii-keyset))

(doc (subsubsub*section "TeleVideo Keydecs"))

(doc (defthing charterm-tvi925-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "tvi925")
             ".")))
(provide charterm-tvi925-keydec)
(define  charterm-tvi925-keydec
  (charterm-make-keydec 'tvi925
                        charterm-televideo-925-keyset
                        charterm-ascii-keyset))

(doc (subsubsub*section "ASCII Keydecs"))

(doc (defthing charterm-ascii-keydec charterm-keydec?
       (para (tech "Keydec")
             " for "
             (tech "termvar")
             " "
             (racket "ascii")
             ".")))
(provide charterm-ascii-keydec)
(define  charterm-ascii-keydec
  (charterm-make-keydec 'ascii
                        charterm-ascii-keyset))

(doc (subsubsub*section "Default Keydecs"))

(doc (defthing charterm-ansi-keydec charterm-keydec?
       (para (tech "Keydec")
             " for any presumed ANSI-ish terminal, combining many ANSI-ish "
             (tech "keysets")
             ".")))
(define charterm-ansi-keydec
  (charterm-make-keydec 'ansi
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-xterm-new-keyset
                        charterm-linux-keyset
                        charterm-rxvt-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-ascii-keyset))

(doc (defthing charterm-insane-keydec charterm-keydec?
       (para (tech "Keydec")
             " for the uniquely desperate situation of wanting to possibly have
extensive key decoding for a terminal that might not even be ansi, but be
Wyse, TeleVideo, or some other ASCII.")))
(provide charterm-insane-keydec)
(define  charterm-insane-keydec
  (charterm-make-keydec 'insane
                        charterm-xterm-new-keyset
                        charterm-linux-keyset
                        charterm-dec-vt220-keyset
                        charterm-dec-vt100-keyset
                        charterm-linux-keyset
                        charterm-xterm-xfree86-keyset
                        charterm-xterm-x11r6-keyset
                        charterm-wyse-wy50-keyset
                        charterm-televideo-925-keyset
                        charterm-ascii-keyset))

(doc (subsection "Termvar")

     (para "A "
           (deftech "termvar")
           " is what the "
           (code "charterm")
           " package calls the value of the Unix-like "
           (code "TERM")
           " environment variable.  Each "
           (tech "termvar")
           " has a default "
           (tech "protocol")
           " and "
           (tech "keydec")
           ".  Note, however, that "
           (code "TERM")
           " is not always a precise indicator of the best protocol and keydec,
but by default we work with what we have."))

;; TODO: Document the termvars here?  Move this subsection?

(doc (section (code "charterm") " Object")

     (para "The "
           (racket charterm)
           " object captures the state of a session with a particular terminal.")

     (para "A "
           (racket charterm)
           " object is also a synchronizable event, so it can be used with
procedures such as "
           (racket sync)
           ".  As an event, it becomes ready when there is at least one byte
available for reading from the terminal, and its synchronization result is
itself."))

(doc (defproc (charterm? (x any/c))
         boolean?
       (para "Predicate for whether or not "
             (var x)
             " is a "
             (racket charterm)
             ".")))
(provide charterm?)

(doc (defproc (charterm-termvar (ct charterm?))
         (or/c #f string?))
     (para "Gets the "
           (tech "termvar")
           "."))
(provide charterm-termvar)

(doc (defproc (charterm-protocol (ct charterm?))
         symbol?)
     (para "Gets the "
           (tech "protocol")
           "."))
(provide charterm-protocol)

(doc (defproc (charterm-keydec (ct charterm?))
         symbol?)
     (para "Gets the "
           (tech "keydec")
           "."))
(provide (rename-out (charterm-keydec* charterm-keydec)))

(define-struct charterm
  (tty
   in
   out
   evt
   buf-size
   buf
   (buf-start #:mutable)
   (buf-end #:mutable)
   termvar
   protocol
   keydec*
   (screensize #:mutable))
  #:property prop:evt (struct-field-index evt))

(define (%charterm:protocol-unimplemented error-name ct)
  (error error-name
         "protocol unimplemented: ~S"
         (charterm-protocol ct)))

(define (%charterm:protocol-unreachable error-name ct)
  (error error-name
         "internal error: protocol unreachable: ~S"
         (charterm-protocol ct)))

(define %charterm:stty-minus-f-arg-string
  (case (system-type 'os)
    ((macosx) "-f")
    (else     "-F")))
  
(doc (defparam current-charterm ct (or/c #f charterm?)
       (para "This parameter provides the default "
             (racket charterm)
             " for most of the other procedures.  It is usually set automatically by "
             (racket call-with-charterm)
             ", "
             (racket with-charterm)
             ", "
             (racket open-charterm)
             ", and "
             (racket close-charterm)
             ".")))
(provide current-charterm)
(define current-charterm (make-parameter #f))

(doc (defproc (open-charterm
               (#:tty      tty      (or/c #f path-string?) #f)
               (#:current? current? boolean?               #t))
         charterm?
       (para "Returns an open "
             (racket charterm)
             " object, by opening I/O ports on the terminal device at "
             (racket tty)
             " (or, if "
             (racket #f)
             ", file "
             (filepath "/dev/tty")
             "), and setting raw mode and disabling echo (via "
             (filepath "/bin/stty")
             ").  If "
             (racket current?)
             " is true, the "
             (racket current-charterm)
             " parameter is also set to this object.")))
(provide open-charterm)
(define (open-charterm #:tty      (tty      #f)
                       #:current? (current? #t))
  (let* ((tty (cleanse-path (or tty "/dev/tty")))
         (tty-str  (path->string tty)))
    (or (system* "/bin/stty"
                 %charterm:stty-minus-f-arg-string
                 tty-str
                 "raw"
                 "-echo")
        (error 'open-charterm
               "stty ~S failed"
               tty-str))
    (with-handlers ((exn:fail? (lambda (e)
                                 (with-handlers ((exn:fail? void))
                                   (system* "/bin/stty"
                                            %charterm:stty-minus-f-arg-string
                                            tty-str
                                            "sane"))
                                 (raise e))))
      (let*-values (((in out)   (open-input-output-file tty
                                                        #:exists 'update))
                    ((buf-size) 2048))
        ;; TODO: Do we actually need to turn off buffering?
        (file-stream-buffer-mode in  'none)
        (file-stream-buffer-mode out 'none)
        (let*-values
            (((termvar) (getenv "TERM"))
             ((termvar) (cond ((not termvar) #f)
                              ((equal? "" termvar) #f)
                              (else (string-downcase termvar))))
             ((protocol keydec)
              ;; TODO: Once the patterns have been fleshed out, make the exact
              ;; matches a hash, and optimize the regexps.
              (cond ((not termvar) (values #f #f))
                    ;; Exact Matches:
                    ((equal? "ascii"     termvar) (values 'ascii         charterm-ascii-keydec))
                    ((equal? "dumb"      termvar) (values 'ascii         charterm-ascii-keydec))
                    ((equal? "linux"     termvar) (values 'ansi      charterm-linux-keydec))
                    ((equal? "rxvt"      termvar) (values 'ansi      charterm-rxvt-keydec))
                    ((equal? "screen"    termvar) (values 'ansi      charterm-screen-keydec))
                    ((equal? "tvi925"    termvar) (values 'televideo-925 charterm-tvi925-keydec))
                    ((equal? "tvi950"    termvar) (values 'televideo-925 charterm-tvi925-keydec))
                    ((equal? "vt100"     termvar) (values 'ansi      charterm-vt100-keydec))
                    ((equal? "vt102"     termvar) (values 'ansi      charterm-vt100-keydec))
                    ((equal? "vt220"     termvar) (values 'ansi      charterm-vt220-keydec))
                    ((equal? "wy50"      termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "wy60"      termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "wy75"      termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "wyse50"    termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "wyse60"    termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "wyse75"    termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((equal? "xterm"     termvar) (values 'ansi      charterm-xterm-new-keydec))
                    ((equal? "xterm-new" termvar) (values 'ansi      charterm-xterm-new-keydec))
                    ;; ANSI-ish Guesses:
                    ((regexp-match #rx"ansi$"  termvar) (values 'ansi charterm-ansi-keydec))
                    ((regexp-match #rx"^ansi"  termvar) (values 'ansi charterm-ansi-keydec))
                    ((regexp-match #rx"^xterm" termvar) (values 'ansi charterm-xterm-new-keydec))
                    ((regexp-match #rx"^rxvt"  termvar) (values 'ansi charterm-rxvt-keydec))
                    ((regexp-match #rx"^vt"    termvar) (values 'ansi charterm-rxvt-keydec))
                    ;; Non-ANSI Guesses:
                    ((regexp-match #rx"^wy"  termvar) (values 'wyse-wy50     charterm-wy50-keydec))
                    ((regexp-match #rx"^tvi" termvar) (values 'televideo-925 charterm-tvi925-keydec))
                    ;; Default:
                    (else (values #f #f))))
             ((protocol keydec)
              (values (or protocol 'ansi)
                      (or keydec charterm-ansi-keydec))))
          (letrec ((wrapping-evt (wrap-evt in
                                           (lambda (evt) ct)))
                   (ct (make-charterm tty-str               ; tty
                                      in                    ; in
                                      out                   ; out
                                      wrapping-evt          ; evt
                                      buf-size              ; buf-size
                                      (make-bytes buf-size) ; buf
                                      0                     ; buf-start
                                      0                     ; buf-end
                                      termvar               ; termvar
                                      protocol              ; protocol
                                      keydec                ; keydec
                                        ; screensize
                                      (if (and (eq? protocol 'ansi)
                                               (not (member termvar '("screen"))))
                                          'control/stty/none
                                          'stty/none))))
            (and current?
                 (current-charterm ct))
            ct))))))

(doc (defproc (close-charterm (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Closes "
             (racket ct)
             " by closing the I/O ports, and undoing "
             (racket open-charterm)
             "'s changes via "
             (filepath "/bin/stty")
             ".  If "
             (racket current-charterm)
             " is set to "
             (racket ct)
             ", then that parameter will be changed to "
             (racket #f)
             " for good measure.  You might wish to use "
             (racket with-charterm)
             " instead of worrying about calling "
             (racket close-charterm)
             " directly.")
       (para "Note: If you exit your Racket process without properly closing the "
             (racket charterm)
             ", your terminal may be left in a crazy state.  You can fix it with
the command:")
       (commandline "stty sane")))
(provide close-charterm)
(define (close-charterm #:charterm (ct (current-charterm)))
  (with-handlers ((exn:fail? void)) (close-input-port  (charterm-in ct)))
  (with-handlers ((exn:fail? void)) (close-output-port (charterm-out ct)))
  ;; TODO: Set the port fields of the struct to #f?
  (if (with-handlers ((exn:fail? (lambda (e) #f)))
        (system* "/bin/stty"
                 %charterm:stty-minus-f-arg-string
                 (charterm-tty ct)
                 "cooked"
                 "echo"))
      (if (eq? ct (current-charterm))
          (current-charterm #f)
          (void))
      (error 'close-charterm
             "stty failed")))

;; (define (call-with-charterm proc #:tty (tty #f))
;;   (let* ((tty (cleanse-path tty))
;;          (ct  (open-charterm #:tty tty #:current? #f)))
;;     (dynamic-wind
;;       void
;;       (lambda ()
;;         (proc ct))
;;       (lambda ()
;;         (close-charterm #:charterm ct)))))

(doc (defform (with-charterm expr? ...))
     (para "Opens a "
           (racket charterm)
           " and evaluates the body expressions in sequence with "
           (racket current-charterm)
           " set appropriately.  When control jumps out of the body, in a
manner of speaking, the "
           (racket charterm)
           " is closed."))
(provide with-charterm)
(define-syntax (with-charterm stx)
  (syntax-case stx ()
    ((_ BODY0 BODYn ...)
     #'(let ((ct #f))
         (dynamic-wind
           (lambda ()
             (set! ct (open-charterm #:current? #t)))
           (lambda ()
             BODY0 BODYn ...)
           (lambda ()
             (close-charterm #:charterm ct)
             (set! ct #f)))))))

(doc (section "Terminal Information"))

(doc (defproc (charterm-screen-size (#:charterm ct charterm? (current-charterm)))
         (values (or/c #f exact-nonnegative-integer?)
                 (or/c #f exact-nonnegative-integer?))
       (para "Attempts to get the screen size, in character columns and rows.
It may do this through a control sequence or through "
             (code "/bin/stty")
             ".  If unable to get a value, then default of (80,24) is used.")
       (para "The current behavior in this version of "
             (code "charterm")
             " is to adaptively try different methods of getting screen size,
and to remember what worked for the next time this procedure is called for "
             (racket ct)
             ".  For terminals that are identified as "
             (code "screen")
             " by the "
             (code "TERM")
             " environment variable (e.g., terminal emulators like GNU Screen
and "
             (code "tmux")
             "), the current behavior is to not try the control sequence (which
causes a 1-second delay waiting for a terminal response that never arrives),
and to just use "
             (code "stty")
             ".  For all other terminals, the control sequence is tried first, before trying "
             (code "stty")
             ".  If neither the control sequence nor "
             (code "stty")
             " work, then neither method is tried again for "
             (racket ct)
             ", and instead the procedure always returns ("
             (racket #f)
             ", "
             (racket #f)
             ").  This behavior very well might change in future versions of "
             (code "charterm")
             ", and the author welcomes feedback on which methods work with
which terminals.")))
(provide charterm-screen-size)
(define (charterm-screen-size #:charterm (ct (current-charterm)))
  ;; TODO: Make it store screen side in slots of charterm object too.  Then
  ;; create a "with-resizeable-charterm" form that has a resize handler (or
  ;; maybe make the resize handler an argument to "with-charterm".
  (let loop ()
    (case (charterm-screensize ct)
      ((control) (%charterm:screen-size-via-control ct))
      ((stty)    (%charterm:screen-size-via-stty    ct))
      ;; TODO: Instead of (80,24), maybe be sensitive to termvar.
      ((none)    (values 80 24))
      ((control/stty/none)
       (let-values (((cols rows) (%charterm:screen-size-via-control ct)))
         (if (and cols rows)
             (values cols rows)
             (begin (set-charterm-screensize! ct 'stty/none)
                    (loop)))))
      ((stty/none)
       (let-values (((cols rows) (%charterm:screen-size-via-stty ct)))
         (if (and cols rows)
             (values cols rows)
             (begin (set-charterm-screensize! ct 'none)
                    (loop)))))
      (else (error 'charterm-screen-size
                   "invalid screensize ~S"
                   (charterm-screensize ct))))))

(define (%charterm:screen-size-via-control ct)
  (%charterm:protocol-case
   '%charterm:screen-size-via-control
   (charterm-protocol ct)
   ((ansi)
    (%charterm:write-bytes ct #"\e[18t")
    (cond ((%charterm:read-regexp-response ct #rx#"\e\\[8;([0-9]+);([0-9]+)t")
           => (lambda (m)
                (values (%charterm:bytes-ascii->nonnegative-integer (list-ref m 1))
                        (%charterm:bytes-ascii->nonnegative-integer (list-ref m 0)))))
          ;; TODO: We could do "ioctl" "TIOCGWINSZ", but that means FFI.
          ;;
          ;; TODO: We could execute "stty -a" (or perhaps "stty -g") to get
          ;; around doing an FFI call.
          (else (values #f #f))))
   ((wyse-wy50 televideo-925)
    (%charterm:protocol-unreachable '%charterm:screen-size-via-control ct))))

(define (%charterm:screen-size-via-stty ct)
  (let* ((stdout (open-output-bytes))
         (stderr (open-output-bytes))
         (proc   (list-ref (process*/ports stdout
                                           (open-input-bytes #"")
                                           stderr
                                           "/bin/stty"
                                           %charterm:stty-minus-f-arg-string
                                           (charterm-tty ct)
                                           "-a")
                           4))
         (bstr   (begin (proc 'wait)
                        (get-output-bytes stdout))))
    (if (eq? 'done-ok (proc 'status))
        (let-values (((width height)
                      (cond ((regexp-match-positions
                              #rx#"rows +([0-9]+);.*columns +([0-9]+)"
                              bstr)
                             => (lambda (m)
                                  (values (%charterm:bytes-ascii->nonnegative-integer
                                           (subbytes bstr (caaddr m) (cdaddr m)))
                                          (%charterm:bytes-ascii->nonnegative-integer
                                           (subbytes bstr (caadr  m) (cdadr m))))))
                            ((regexp-match-positions
                              #rx#"columns +([0-9]+);.*rows +([0-9]+)"
                              bstr)
                             => (lambda (m)
                                  (values (%charterm:bytes-ascii->nonnegative-integer
                                           (subbytes bstr (caadr  m) (cdadr m)))
                                          (%charterm:bytes-ascii->nonnegative-integer
                                           (subbytes bstr (caaddr m) (cdaddr m))))))
                            (else #f #f))))
          ;; Note: These checks for 0 are for if "stty" returns 0, such as
          ;; seems to happen in the emulator on the Wyse S50 when in SSH rather than Telnet.
          (values (if (zero? width)  #f width)
                  (if (zero? height) #f height)))
        (values #f #f))))

(doc (section "Display Control"))

(define (%charterm:shift-buf ct)
  (let ((buf-start (charterm-buf-start ct))
        (buf-end   (charterm-buf-end   ct)))
    (if (= buf-start buf-end)
        ;; Buffer is empty, so are buf-start and buf-end at 0?
        (if (zero? buf-end)
            (void)
            (begin (set-charterm-buf-start! ct 0)
                   (set-charterm-buf-end!   ct 0)))
        ;; Buffer is not empty, so is buf-start at 0?
        ;;
        ;; TODO: Maybe make this shift only if we need to to free N additional
        ;; bytes at the end?
        (if (zero? buf-start)
            (void)
            (let ((buf (charterm-buf ct)))
              (bytes-copy! buf 0 buf buf-start buf-end)
              (set-charterm-buf-start! ct 0)
              (set-charterm-buf-end!   ct (- buf-end buf-start)))))))

(define (%charterm:read-into-buf/timeout ct timeout)
  (let ((in (charterm-in ct)))
    (let loop ()
      (let ((sync-result (sync/timeout/enable-break timeout in)))
        (cond ((not sync-result) #f)
              ((eq? sync-result in)
               ;; TODO: if buf is empty, then read into start 0!
               (let ((read-result (read-bytes-avail! (charterm-buf      ct)
                                                     in
                                                     (charterm-buf-end  ct)
                                                     (charterm-buf-size ct))))
                 (if (zero? read-result)
                     ;; TODO: If there's a timeout, subtract from it?
                     (loop)
                     (begin (set-charterm-buf-end! ct (+ (charterm-buf-end ct) read-result))
                            read-result))))
              (else (error '%charterm:read-into-buf/timeout
                           "*DEBUG* sync returned ~S"
                           sync-result)))))))

(define (%charterm:read-regexp-response ct rx #:timeout-seconds (timeout-seconds 1.0))
  (let ((in (charterm-in ct)))
    (%charterm:shift-buf ct)
    ;; TODO: Implement timeout better, by checking clock and doing
    ;; sync/timeout, or by setting timer.
    (let loop ((timeout-seconds timeout-seconds))
      (if (= (charterm-buf-end ct) (charterm-buf-size ct))
          (begin
            ;; TODO: Make this an exception instead of #f?
            #f)
          (begin (or (let ((buf       (charterm-buf       ct))
                           (buf-start (charterm-buf-start ct))
                           (buf-end   (charterm-buf-end   ct)))
                       (cond ((regexp-match-positions rx
                                                      buf
                                                      buf-start
                                                      buf-end)
                              => (lambda (m)
                                   ;; TODO: Audit and test some of this buffer
                                   ;; code here and elsewhere.
                                   (let ((match-start (caar m))
                                         (match-end   (cdar m)))
                                     (if (= match-start buf-start)
                                         (set-charterm-buf-start! ct match-end)
                                         (if (= match-end buf-end)
                                             (set-charterm-buf-end! ct match-start)
                                             (begin (bytes-copy! buf
                                                                 match-start
                                                                 buf
                                                                 match-end
                                                                 buf-end)
                                                    (set-charterm-buf-end! ct
                                                                           (+ match-start
                                                                              (- buf-end
                                                                                 match-end)))))))

                                   (map (lambda (pos)
                                          (subbytes buf (car pos) (cdr pos)))
                                        (cdr m))))
                             (else #f)))
                     (if (%charterm:read-into-buf/timeout ct timeout-seconds)
                         (loop timeout-seconds)
                         #f
                         )))))))

(define (%charterm:bytes-ascii->nonnegative-integer bstr)
  (let ((bstr-len (bytes-length bstr)))
    (let loop ((i      0)
               (result 0))
      (if (= i bstr-len)
          result
          (let* ((b     (bytes-ref bstr i))
                 (b-num (- b 48)))
            (if (<= 0 b-num 9)
                (loop (+ 1 i)
                      (+ (* 10 result) b-num))
                (error '%charterm:bytes-ascii->nonnegative-integer
                       "invalid byte ~S"
                       b)))))))

(doc (subsection "Cursor"))

(doc (defproc (charterm-cursor (x exact-positive-integer?)
                               (y exact-positive-integer?)
                               (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Positions the cursor at column "
             (racket x)
             ", row "
             (racket y)
             ", with the upper-left character cell being (1, 1).")))
(provide charterm-cursor)
(define (charterm-cursor x y #:charterm (ct (current-charterm)))
  (%charterm:position ct x y))

(doc (defproc (charterm-newline (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Sends a newline to the terminal.  This is typically a CR-LF
sequence.")))
(provide charterm-newline)
(define (charterm-newline #:charterm (ct (current-charterm)))
  (%charterm:write-bytes ct #"\r\n"))

(doc (subsection "Displaying"))

(define %charterm:err-byte 63)

(doc (defproc (charterm-display
               (#:charterm ct       charterm?                         (current-charterm))
               (#:width    width    (or/c #f exact-positive-integer?) #f)
               (#:pad      pad      (or/c 'width boolean?)            'width)
               (#:truncate truncate (or/c 'width boolean?)            'width)
               (           arg      any/c) ...)
         void?
       (para "Displays each "
             (racket arg)
             " on the terminal, as if formatted by "
             (racket display)
             ", with the exception that unprintable or non-ASCII characters
might not be displayed.  (The exact behavior of what is permitted is expected
to change in a later version of "
             "CharTerm"
             ", so avoid trying to send your own control sequences or using
newlines, making assumptions about non-ASCII characters, etc.)")
       (para "If "
             (racket width)
             " is a number, then "
             (racket pad)
             " and "
             (racket truncate)
             " specify whether or not to pad with spaces or truncate the output, respectively, to "
             (racket width)
             " characters.  When "
             (racket pad)
             " or "
             (racket width)
             " is "
             (racket 'width)
             ", that is a convenience meaning ``true if, and only if, "
             (racket width)
             " is not "
             (racket #f)
             ".''")))
(provide charterm-display)
(define (charterm-display #:charterm (ct       (current-charterm))
                          #:width    (width    #f)
                          #:pad      (pad      'width)
                          #:truncate (truncate 'width)
                          . args)
  ;; TODO: make it replace unprintable and non-ascii characters with "?".  Even newlines, tabs, etc?
  ;;
  ;; TODO: Do we want buffering?
  (let ((out      (charterm-out ct))
        (pad      (if (eq? 'width pad)      (if width #t #f) pad))
        (truncate (if (eq? 'width truncate) (if width #t #f) truncate)))
    (and pad      (not width) (error 'charterm-display "#:pad cannot be true if #:width is not"))
    (and truncate (not width) (error 'charterm-display "#:truncate cannot be true if #:width is not"))
    (let loop ((args            args)
               (remaining-width (or width 0)))
      (if (null? args)
          (if (and pad (> remaining-width 0))
              ;; TODO: Get rid of this allocation.
              (begin (%charterm:write-bytes ct (make-bytes remaining-width 32))
                     (void))
              (void))
          (let* ((arg (car args))
                 (bytes (cond ((bytes? arg)
                               arg)
                              ((string? arg)
                               (string->bytes/latin-1 arg
                                                      %charterm:err-byte
                                                      0
                                                      (if truncate
                                                          (min (string-length arg)
                                                               remaining-width)
                                                          (string-length arg))))
                              ((number? arg)
                               (string->bytes/latin-1 (number->string arg)
                                                      %charterm:err-byte))
                              (else (let ((arg (format "~A" arg)))
                                      (string->bytes/latin-1 arg
                                                             %charterm:err-byte
                                                             0
                                                             (if truncate
                                                                 (min (string-length arg)
                                                                      remaining-width)
                                                                 (string-length arg)))))))
                 (remaining-width (- remaining-width (bytes-length bytes))))
            (cond ((or (not truncate) (> remaining-width 0))
                   (%charterm:write-bytes ct bytes)
                   (loop (cdr args)
                         remaining-width))
                  ((zero? remaining-width)
                   (%charterm:write-bytes ct bytes)
                   (void))
                  (else (%charterm:write-subbytes ct bytes 0 (+ (bytes-length bytes)
                                                                remaining-width))
                        (void))))))))

(define (%charterm:send-code ct . args)
  ;; TODO: Do we want buffering?
  (let ((out (charterm-out ct)))
    (let loop ((args args))
      (if (null? args)
          (void)
          (let ((arg (car args)))
            (cond ((bytes? arg)
                   (write-bytes arg out))
                  ((string? arg)
                   (write-string arg out))
                  ((integer? arg)
                   (display (inexact->exact arg) out))
                  ((pair? arg)
                   (loop (car arg))
                   (loop (cdr arg)))
                  (else (error '%charterm:send-code
                               "don't know how to send ~S"
                               arg)))
            (loop (cdr args)))))))

;; (define %charterm:2-digit-bytes-vector
;;   (vector #"00" #"01" #"02" #"03" #"04" #"05" #"06" #"07"
;;           #"08" #"09" #"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" #"68" #"69" #"70"
;;           #"72" #"73" #"74" #"75" #"76" #"77" #"78" #"79"
;;           #"80" #"81" #"82" #"83" #"84" #"85" #"86" #"87"))

(define %charterm:televideo-925-cursor-position-to-byte-vector
  (list->vector (cons #f
                      (for/list ((n (in-range 1 96)))
                        (+ 31 n)))))

;; (provide/contract with error-checks on args
(define (%charterm:position ct x y)
  (%charterm:protocol-case
   '%charterm:position
   (charterm-protocol ct)
   ((ansi)
    (if (and (= 1 x) (= 1 y))
        (%charterm:write-bytes ct #"\e[;H")
        (%charterm:send-code ct #"\e[" y #";" x #"H")))
   ((wyse-wy50)
    ;; Note: We are using the WY-50 long codes because we don't know
    ;; confidently that we are an 80-column screen.
    (if (and (= 1 x) (= 1 y))
        (%charterm:write-bytes ct #"\ea1R1C")
        (%charterm:send-code ct #"\ea" y #"R" x #"C")))
   ((televideo-925)
    (if (and (= 1 x) (= 1 y))
        (%charterm:write-bytes ct #"\e=  ")
        (begin (%charterm:write-bytes ct #"\e=")
               (%charterm:write-byte ct (vector-ref %charterm:televideo-925-cursor-position-to-byte-vector y))
               (%charterm:write-byte ct (vector-ref %charterm:televideo-925-cursor-position-to-byte-vector x)))))))

(doc (subsection "Video Attributes"))

;; TODO: !!! document link to protocol section

;; TODO: !!! define "charterm-has-video-attributes?"

(doc (defproc*
         (((charterm-normal    (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-inverse   (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-underline (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-blink     (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-bold      (#:charterm ct charterm? (current-charterm))) void?))
       (para "Sets the "
             (deftech "video attributes")
             " for subsequent writes to the terminal.  In this version of "
             (code "charterm")
             ", each is mutually-exclusive, so, for example, setting "
             (italic "bold")
             " clears "
             (italic "inverse")
             ". Note that that video attributes are currently supported only for protocol "
             (racket 'ansi)
             ", due to limitations of the TeleVideo and Wyse models for
video attributes.")))

(provide charterm-normal)
(define (charterm-normal #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-normal
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[m"))
   ((wyse-wy50)     (void)) ; (%charterm:write-bytes ct #"\eA00"))
   ((televideo-925) (void))))

(provide charterm-inverse)
(define (charterm-inverse #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-inverse
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[;7m"))
   ((wyse-wy50)     (void)) ; (%charterm:write-bytes ct #"\eA04"))
   ((televideo-925) (void))))

(provide charterm-underline)
(define (charterm-underline #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-underline
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[4m"))
   ((wyse-wy50)     (void)) ; (%charterm:write-bytes ct #"\eA08"))
   ((televideo-925) (void))))

(provide charterm-blink)
(define (charterm-blink #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-blink
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[5m"))
   ((wyse-wy50)     (void)) ; (%charterm:write-bytes ct #"\eA02"))
   ((televideo-925) (void))))

(provide charterm-bold)
(define (charterm-bold #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-bold
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[1m"))
   ((wyse-wy50)     (void)) ; (%charterm:write-bytes ct #"\eA0<"))
   ((televideo-925) (void))))

(doc (subsection "Clearing"))

(doc (defproc (charterm-clear-screen (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Clears the screen, including first setting the video attributes to
normal, and positioning the cursor at (1, 1).")))
(provide charterm-clear-screen)
(define (charterm-clear-screen #:charterm (ct (current-charterm)))
  ;; TODO: Have a #:style argument?  Or #:background argument?
  (%charterm:protocol-case
   'charterm-clear-screen
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[m\e[2J\e[;H"))
   ((wyse-wy50)     (%charterm:write-bytes ct #"\e+\e*\ea1R1C"))
   ((televideo-925) (%charterm:write-bytes ct #"\e+\e=  "))))

(doc (defproc*
         (((charterm-clear-line       (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-clear-line-left  (#:charterm ct charterm? (current-charterm))) void?)
          ((charterm-clear-line-right (#:charterm ct charterm? (current-charterm))) void?))
       (para "Clears text from the line with the cursor, or part of the line with the cursor.")))

(provide charterm-clear-line)
(define (charterm-clear-line #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm:clear-line
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[2K"))
   ((televideo-925) (%charterm:write-bytes ct #"\r\eT"))
   ;; TODO: wyse-wy50 is clearing to nulls, not spaces.
   ((wyse-wy50)     (%charterm:write-bytes ct #"\r\et"))))

(provide charterm-clear-line-left)
(define (charterm-clear-line-left #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-clear-line-left
   (charterm-protocol ct)
   ((ansi) (%charterm:write-bytes ct #"\e[1K"))
   ((televideo-925 wyse-wy50)
    ;; TODO: Do this by getting cursor position, then reposition and write spaces?
    (%charterm:unimplemented ct 'clearterm-clear-line-left))))

(provide charterm-clear-line-right)
(define (charterm-clear-line-right #:charterm (ct (current-charterm)))
  (%charterm:protocol-case
   'charterm-clear-line-right
   (charterm-protocol ct)
   ((ansi)      (%charterm:write-bytes ct #"\e[K"))
   ((televideo-925) (%charterm:write-bytes ct #"\eT"))
   ;; TODO: wyse-wy50 is clearing to nulls, not spaces.
   ((wyse-wy50)     (%charterm:write-bytes ct #"\et"))))

(doc (subsection "Line Insert and Delete"))

(doc (defproc (charterm-insert-line (count exact-positive-integer? 1)
                                    (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Inserts "
             (racket count)
             " blank lines at cursor.  Note that not all terminals support
this.")))
(provide charterm-insert-line)
(define (charterm-insert-line (count 1) #:charterm (ct (current-charterm)))
  (if (integer? count)
      (cond ((= count 0) (void))
            ((> count 0)
             (%charterm:protocol-case
              'charterm-insert-line
              (charterm-protocol ct)
              ((ansi)                (%charterm:send-code ct #"\e[" count "L"))
              ((wyse-wy50 televideo-925) (%charterm:write-bytes ct #"\eE"))))
            (else (error 'charterm-insert-line
                         "invalid count: ~S"
                         count)))
      (error 'charterm-insert-line
             "invalid count: ~S"
             count)))

(doc (defproc (charterm-delete-line (count exact-positive-integer? 1)
                                    (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Deletes "
             (racket count)
             " blank lines at cursor.  Note that not all terminals support
this.")))
(provide charterm-delete-line)
(define (charterm-delete-line (count 1) #:charterm (ct (current-charterm)))
  (if (integer? count)
      (cond ((= count 0) (void))
            ((> count 0)
             (%charterm:protocol-case
              'charterm-delete-line
              (charterm-protocol ct)
              ((ansi)
               (%charterm:send-code ct #"\e[" count "M"))
              ((wyse-wy50 televideo-925)
               (if (= 1 count)
                   (%charterm:write-bytes ct #"\eR")
                   (let ((bstr (make-bytes (* 2 count) 82)))
                     (let loop ((n (* 2 (- count 1))))
                       (bytes-set! bstr n 27)
                       (if (zero? n)
                           (%charterm:write-bytes ct bstr)
                           (loop (- n 2)))))))))
            (else (error 'charterm-delete-line
                         "invalid count: ~S"
                         count)))
      (error 'charterm-delete-line
             "invalid count: ~S"
             count)))

(doc (subsubsection "Misc. Output"))

(doc (defproc (charterm-bell (#:charterm ct charterm? (current-charterm)))
         void?
       (para "Rings the terminal bell.  This bell ringing might manifest as a
beep, a flash of the screen, or nothing.")))
(provide charterm-bell)
(define (charterm-bell #:charterm (ct (current-charterm)))
  (%charterm:write-bytes ct #"\007"))

(doc (section "Keyboard Input")

     ;; TODO: !!! document link to terminal diversity section

     (para "Normally you will get keyboard input using the "
           (racket charterm-read-key)
           " procedure."))

(doc (defproc (charterm-byte-ready? (#:charterm ct charterm? (current-charterm)))
         boolean?
       (para "Returns true/false for whether at least one byte is ready for
reading (either in a buffer or on the port) from "
             (racket ct)
             ".  Note that, since some keys are encoded as multiple bytes, just
because this procedure returns true doesn't mean that "
             (racket charterm-read-key)
             " won't block temporarily because it sees part of a potential
multiple-byte key encoding.")))
(provide charterm-byte-ready?)
(define (charterm-byte-ready? #:charterm (ct (current-charterm)))
  (or (> (charterm-buf-end ct) (charterm-buf-start ct))
      (byte-ready? (charterm-in ct))))

(doc (defproc (charterm-read-key
               (#:charterm ct      charterm?           (current-charterm))
               (#:timeout  timeout (or/c #f positive?) #f))
         (or #f char? symbol?)
       (para "Reads a key from "
             (racket ct)
             ", blocking indefinitely or until sometime after "
             (racket timeout)
             " seconds has been reached, if "
             (racket timeout)
             " is non-"
             (racket #f)
             ".  If timeout is reached, "
             (racket #f)
             " is returned.")
       (para "Many keys are returned as characters, especially ones that
correspond to printable characters.  For example, the unshifted "
             (bold "Q")
             " key is returned as character "
             (racket #\q)
             ".  Some other keys are returned as symbols, such as "
             (racket 'return)
             ", "
             (racket 'escape)
             ", "
             (racket 'f1)
             ", "
             (racket 'shift-f12)
             ", "
             (racket 'right)
             ", and many others.")
       (para "Since some keys are sent as ambiguous sequences, "
             (racket charterm-read-key)
             " employs separate timeouts internally, such as to disambuate
the "
             (bold "Esc")
             " key (byte sequence 27) from what on some terminals would be
the "
             (bold "F10")
             " key (bytes sequence 27, 91, 50, 49, 126).")))
(provide charterm-read-key)
(define (charterm-read-key #:charterm (ct      (current-charterm))
                           #:timeout  (timeout #f))
  (%charterm:read-keyinfo-or-key 'charterm-read-key ct timeout #f))

(doc (defproc (charterm-read-keyinfo
               (#:charterm ct      charterm?           (current-charterm))
               (#:timeout  timeout (or/c #f positive?) #f))
         charterm-keyinfo?
       (para "Like "
             (racket charterm-read-keyinfo)
             " except instead of returning a "
             (tech "keycode")
             ", it returns a "
             (tech "keyinfo")
             ".")))
(provide charterm-read-keyinfo)
(define (charterm-read-keyinfo #:charterm (ct      (current-charterm))
                               #:timeout  (timeout #f))
  (%charterm:read-keyinfo-or-key 'charterm-read-keyinfo ct timeout #t))

(define (%charterm:read-keyinfo-or-key error-name ct timeout keyinfo?)
  ;; TODO: Maybe make this shift decision smarter -- compile the key tree ahead
  ;; of time so we know the max depth, and then we know exactly the max space
  ;; we will need for this call.
  (and (< (- (charterm-buf-size ct)
             (charterm-buf-start ct))
          10)
       (%charterm:shift-buf ct))
  (let ((buf       (charterm-buf        ct))
        (buf-start (charterm-buf-start  ct))
        (buf-end   (charterm-buf-end    ct))
        (buf-size  (charterm-buf-size   ct))
        (keydec    (charterm-keydec*    ct))
        (b1        (%charterm:read-byte/timeout ct timeout)))
    (if b1
        (or (let loop ((tree        (charterm-keydec-primary-keytree keydec))
                       (probe-start (+ 1 buf-start))
                       (b           b1))
              (cond ((hash-ref tree b #f)
                     => (lambda (code-or-subtree)
                          (cond ((hash? code-or-subtree)
                                 ;; We have more subtree to search.
                                 (if (or (< probe-start buf-end)
                                         (and (< buf-end buf-size)
                                              (%charterm:read-into-buf/timeout ct 0.5)))
                                     ;; We have at least one more byte, so recurse.
                                     (loop code-or-subtree
                                           (+ 1 probe-start)
                                           (bytes-ref buf probe-start))
                                     ;; We have hit timeout or end of buffer, so
                                     ;; just accept the original byte.
                                     #f))
                                ((charterm-keyinfo? code-or-subtree)
                                 ;; We found our keyinfo, so consume the input and return the value.
                                 (begin (set-charterm-buf-start! ct probe-start)
                                        (if keyinfo?
                                            code-or-subtree
                                            (charterm-keyinfo-keycode code-or-subtree))
                                        ))
                                (else (error error-name
                                             "invalid object in keytree keyinfo position: ~S"
                                             code-or-subtree)))))
                    (else #f)))
            ;; We didn't find a key code, so try secondary keytree with initial byte.
            (cond ((hash-ref (charterm-keydec-secondary-keytree keydec) b1 #f)
                   => (lambda (keyinfo)
                        (if keyinfo?
                            keyinfo
                            (charterm-keyinfo-keycode keyinfo))))
                  (else (if keyinfo?
                            ;; TODO: Cache these keyinfos for unrecognized keys
                            ;; in the charterm object, or make a fallback
                            ;; keyset for them (although the fallback keyset,
                            ;; while it works for 8-bit characters, becomes
                            ;; less practical if we implement multibyte).
                            (make-charterm-keyinfo #f
                                                   #f
                                                   (list b1)
                                                   "???"
                                                   b1
                                                   (list b1))
                            (integer->char b1)))))
        ;; Got a timeout, so return #f.
        #f)))

(define (%charterm:write-byte ct byt)
  (write-byte byt (charterm-out ct)))

(define (%charterm:write-bytes ct bstr . rest-bstrs)
  (write-bytes bstr (charterm-out ct))
  (or (null? rest-bstrs)
      (for-each (lambda (bstr)
                  (write-bytes bstr (charterm-out ct)))
                rest-bstrs)))

(define (%charterm:write-subbytes ct bstr start end)
  (write-bytes bstr (charterm-out ct) start end))

(define (%charterm:read-byte/timeout ct timeout)
  (let ((buf-start (charterm-buf-start ct)))
    (if (or (< buf-start (charterm-buf-end ct))
            (%charterm:read-into-buf/timeout ct timeout))
        (begin0 (bytes-ref (charterm-buf ct) buf-start)
          (set-charterm-buf-start! ct (+ 1 buf-start)))
        #f)))

(define (%charterm:read-byte ct)
  (%charterm:read-byte/timeout ct #f))

(doc (section "References")

     (para "[" (deftech "ANSI X3.64") "] "
           (url "http://en.wikipedia.org/wiki/ANSI_escape_code"))

     (para "[" (deftech "ASCII") "] "
           (url "http://en.wikipedia.org/wiki/Ascii"))
     
     (para "[" (deftech "ECMA-43") "] "
           (hyperlink "http://www.ecma-international.org/publications/standards/Ecma-043.htm"
                      (italic "Standard ECMA-43: 8-bit Coded Character Set Structure and Rules"))
           ", 3rd Ed., 1991-12")

     (para "[" (deftech "ECMA-48") "] "
           (hyperlink "http://www.ecma-international.org/publications/standards/Ecma-048.htm"
                      (italic "Standard ECMA-48: Control Functions for Coded Character Sets"))
           ", 5th Ed., 1991-06")

     (para "[" (deftech "Gregory") "] "
           "Phil Gregory, ``"
           (hyperlink "http://aperiodic.net/phil/archives/Geekery/term-function-keys.html"
                      "Terminal Function Key Escape Codes")
           ",'' 2005-12-13 Web post, as viewed on 2012-06")

     (para "[" (deftech "PowerTerm") "] "
           "Ericom PowerTerm InterConnect 8.2.0.1000 terminal emulator, as run on Wyse S50 WinTerm")

     (para "[" (deftech "TVI-925-IUG") "] "
           (hyperlink "http://vt100.net/televideo/tvi925_ig.pdf"
                      (italic "TeleVideo Model 925 CRT Terminal Installation and User's Guide")))

     (para "[" (deftech "TVI-950-OM") "] "
           (hyperlink "http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/televideo/Operators_Manual_Model_950_1981.pdf"
                      (italic "TeleVideo Operator's Manual Model 950"))
           ", 1981")
     
     (para "[" (deftech "VT100-TM") "] "
           "Digital Equipment Corp., "
           (hyperlink "http://vt100.net/docs/vt100-tm/"
                      (italic "VT100 Series Technical Manual"))
           ", 2nd Ed., 1980-09")
     
     (para "[" (deftech "VT100-UG") "] "
           "Digital Equipment Corp., "
           (hyperlink "http://vt100.net/docs/vt100-ug/"
                      (italic "VT100 User Guide"))
           ", 3rd Ed., 1981-06")
                      
     (para "[" (deftech "VT100-WP") "] "
           "Wikipedia, "
           (hyperlink "http://en.wikipedia.org/wiki/VT100"
                      "VT100"))

     (para "[" (deftech "WY-50-QRG") "] "
           (hyperlink "http://vt100.net/wyse/wy-50-qrg/wy-50-qrg.pdf"
                      (italic "Wyse WY-50 Display Terminal Quick-Reference Guide")))

     (para "[" (deftech "WY-60-UG") "] "
           (hyperlink "http://vt100.net/wyse/wy-60-ug/wy-60-ug.pdf"
                      (italic "Wyse WY-60 User's Guide")))

     (para "[" (deftech "wy60") "] "
           (hyperlink "http://code.google.com/p/wy60/"
                      (code "wy60")
                      " terminal emulator"))

     (para "[" (deftech "XTerm-ctlseqs") "] "
           "Edward Moy, Stephen Gildea, Thomas Dickey, ``"
           (hyperlink "http://invisible-island.net/xterm/ctlseqs/ctlseqs.html"
                      "Xterm Control Sequences")
           ",'' 2012")

     (para "[" (deftech "XTerm-Dickey") "] "
           (url "http://invisible-island.net/xterm/"))

     (para "[" (deftech "XTerm-FAQ") "] "
           "Thomas E. Dickey, ``"
           (hyperlink "http://invisible-island.net/xterm/xterm.faq.html"
                      "XTerm FAQ")
           ",'' dated 2012")

     (para "[" (deftech "XTerm-WP") "] "
           "Wikipedia, "
           (hyperlink "http://en.wikipedia.org/wiki/Xterm"
                      "xterm"))
           
     )

(doc (section "Known Issues")

     (itemlist

      (item "Need to support ANSI alternate CSI for 8-bit terminals, even
before supporting 8-bit characters and multibyte.")

      (item "Only supports ASCII characters.  Adding UTF-8 support, for terminal emulators
that support it, would be nice.")
      
      (item "Expose the character-decoding mini-language as a configurable
option.  Perhaps wait until we implement timeout-based disambiguation at
arbitrary points in the the DFA rather than just at the top.  Also, might be
better to resolve multi-byte characters first, in case that affects the
mini-language.")

      (item "More controls for terminal features can be added.")
      
      (item "Currently only implemented to work on Unix-like systems like
GNU/Linux.")

      (item "Implement text input controls, either as part of this library or
another, using "
            (racket charterm-demo)
            " as a starting point.")))

;; Note: Different ways to test demo:
;;
;;           racket -t demo.rkt -m
;; screen    racket -t demo.rkt -m
;; tmux -c  "racket -t demo.rkt -m"
;; xterm -e  racket -t demo.rkt -m
;; rxvt -e   racket -t demo.rkt -m
;; wy60 -c   racket -t demo.rkt -m
;;
;; racket -t demo.rkt -m- -n

;; TODO: Source for TeleVideo manuals:
;; http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/televideo/

;; TODO: Add shifted function keys from T60 keyboard (not USB one).

(doc history

     (#:planet 3:1 #:date "2013-05-13"
               (itemlist
                (item "Now uses lowercase "
                      (code "-f")
                      " argument on MacOS X.  (Thanks to Jens Axel S\u00F8gaard for reporting.)")
                (item "Documentation tweaks.")))

     (#:planet 3:0 #:date "2012-07-13"
               (itemlist
                (item "Changed ``"
                      (code "ansi-ish")
                      "'' in identifiers to ``"
                      (code "ansi")
                      "'', hence the PLaneT major version number change.")
                (item "Documentation tweaks.")
                (item "Renamed package from ``"
                      (code "charterm")
                      "'' to ``CharTerm''.")))

     (#:planet 2:5 #:date "2012-06-28"
               (itemlist
                (item "A "
                      (racket charterm)
                      " object is now a synchronizable event.")
                (item "Documentation tweaks.")))
     
     (#:planet 2:4 #:date "2012-06-25"
               (itemlist
                (item "Documentation fix for return type of "
                      (racket charterm-read-keyinfo)
                      ".")))
     
     (#:planet 2:3 #:date "2012-06-25"
               (itemlist
                (item "Fixed problem determining screen size on some
XTerms.  (Thanks to Eli Barzilay for reporting.)")))

     (#:planet 2:2 #:date "2012-06-25"
               (itemlist
                (item "Added another variation of encoding for XTerm arrow,
Home, and End keys.  (Thanks to Eli Barzilay.)")))
     
     (#:planet 2:1 #:date "2012-06-24"
               (itemlist
                (item "Corrected PLaneT version number in "
                      (racket require)
                      " in an example.")))
     
     (#:planet 2:0 #:date "2012-06-24"
               (itemlist
                (item "Greatly increased the sophistication of handling of terminal diversity.")
                (item "Added the "
                      (code "wyse-wy50")
                      " and "
                      (code "televideo-950")
                      " [Correction: "
                      (code "televideo-925")
                      "] protocols, for supporting the native modes of Wyse and
TeleVideo terminals, respectively, and compatibles.")
                (item "More support for different key encodings and termvars.")
                (item "Demo is now in a separate file, mainly for convenience
in giving command lines that run it.  This breaks a command line example
previously documented, so changed PLaneT major version, although the
previously-published example will need to have "
                      (code ":1")
                      " added to it anyway.")
                (item (racket charterm-screen-size)
                      " now defaults to (80,24) when all else fails.")
                (item "Documentation changes.")))

     (#:planet 1:1 #:date "2012-06-17"
               (itemlist
                (item "For "
                      (code "screen")
                      " and "
                      (code "tmux")
                      ", now gets screen size via "
                      (code "stty")
                      ".  This resolves the sluggishness reported with "
                      (code "screen")
                      ".  [Correction: In version 1:1, this behavior is
adaptive for all terminals, with the shortcut for "
                      (tech "termvar")
                      " "
                      (code "screen")
                      " that it doesn't bother trying the control sequence.]")
                (item "Documentation tweaks.")))

     (#:planet 1:0 #:date "2012-06-16"
               (itemlist
                (item "Initial version."))))