about summary refs log tree commit diff stats
path: root/linux/tile/environment.mu
blob: 3c869d3c9fad607fd84a09008409786daea24e1d (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
# The architecture that seems to be crystallizing: the environment has two
# areas: functions and sandbox.
#
# Rendering the environment requires rendering all areas.
# Displaying the cursor requires displaying cursor for the area controlling the cursor.
# Processing events for the environment requires processing events for the area controlling the cursor.
#
# Areas can have dialogs.
# There can also be global dialogs (currently just one: goto function).
# Areas are responsible for rendering their dialogs.
# In practice this results in dialogs encapsulating the state they need to
# decide whether to render.
#
# This will be useful if we add more areas in the future.

type environment {
  screen: (handle screen)
  functions: (handle function)
  sandboxes: (handle sandbox)
  partial-function-name: (handle word)
  # at most one of these will be set
  cursor-function: (handle function)
  cursor-sandbox: (handle sandbox)
  #
  nrows: int
  ncols: int
  code-separator-col: int
}

fn initialize-environment _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  # initialize some predefined function definitions
  var functions/eax: (addr handle function) <- get env, functions
  create-primitive-functions functions
  # initialize first sandbox
  var sandbox-ah/ecx: (addr handle sandbox) <- get env, sandboxes
  allocate sandbox-ah
  var sandbox/eax: (addr sandbox) <- lookup *sandbox-ah
  initialize-sandbox sandbox
  # initialize cursor sandbox
  var cursor-sandbox-ah/eax: (addr handle sandbox) <- get env, cursor-sandbox
  copy-object sandbox-ah, cursor-sandbox-ah
  # initialize screen
  var screen-ah/eax: (addr handle screen) <- get env, screen
  var _screen/eax: (addr screen) <- lookup *screen-ah
  var screen/edi: (addr screen) <- copy _screen
  var nrows/eax: int <- copy 0
  var ncols/ecx: int <- copy 0
  nrows, ncols <- screen-size screen
  var dest/edx: (addr int) <- get env, nrows
  copy-to *dest, nrows
  dest <- get env, ncols
  copy-to *dest, ncols
  var repl-col/ecx: int <- copy ncols
  repl-col <- shift-right 1
  dest <- get env, code-separator-col
  copy-to *dest, repl-col
}

fn initialize-environment-with-fake-screen _self: (addr environment), nrows: int, ncols: int {
  var self/esi: (addr environment) <- copy _self
  var screen-ah/eax: (addr handle screen) <- get self, screen
  allocate screen-ah
  var screen-addr/eax: (addr screen) <- lookup *screen-ah
  initialize-screen screen-addr, nrows, ncols
  initialize-environment self
}

#############
# Iterate
#############

fn process _self: (addr environment), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var fn-name-ah/eax: (addr handle word) <- get self, partial-function-name
  var fn-name/eax: (addr word) <- lookup *fn-name-ah
  compare fn-name, 0
  {
    break-if-=
#?     print-string 0, "processing goto fn\n"
    process-goto-dialog self, key
    return
  }
  var function-ah/eax: (addr handle function) <- get self, cursor-function
  var function/eax: (addr function) <- lookup *function-ah
  compare function, 0
  {
    break-if-=
#?     print-string 0, "processing function\n"
    process-function self, function, key
    return
  }
  var sandbox-ah/eax: (addr handle sandbox) <- get self, cursor-sandbox
  var sandbox/eax: (addr sandbox) <- lookup *sandbox-ah
  compare sandbox, 0
  {
    break-if-=
#?     print-string 0, "processing sandbox\n"
    process-sandbox self, sandbox, key
    return
  }
}

# collect new name in partial-function-name, and move the cursor to function with that name
fn process-goto-dialog _self: (addr environment), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var fn-name-ah/edi: (addr handle word) <- get self, partial-function-name
  # if 'esc' pressed, cancel goto
  compare key, 0x1b/esc
  $process-goto-dialog:cancel: {
    break-if-!=
    clear-object fn-name-ah
    return
  }
  # if 'enter' pressed, location function and set cursor to it
  compare key, 0xa/enter
  $process-goto-dialog:commit: {
    break-if-!=
#?     print-string 0, "jump\n"
    var fn-name/eax: (addr word) <- lookup *fn-name-ah
    var functions/ecx: (addr handle function) <- get self, functions
    var dest/edx: (addr handle function) <- get self, cursor-function
    callee functions, fn-name, dest
    # we won't clear cursor-sandbox until we start supporting multiple sandboxes
    clear-object fn-name-ah
    # there shouldn't be any need to clear state for other dialogs in the sandbox
    return
  }
  #
  compare key, 0x7f/del  # backspace on Macs
  $process-goto-dialog:backspace: {
    break-if-!=
    # if not at start, delete grapheme before cursor
    var fn-name/eax: (addr word) <- lookup *fn-name-ah
    var at-start?/eax: boolean <- cursor-at-start? fn-name
    compare at-start?, 0/false
    {
      break-if-!=
      var fn-name/eax: (addr word) <- lookup *fn-name-ah
      delete-before-cursor fn-name
    }
    return
  }
  # otherwise insert key within current word
  var print?/eax: boolean <- real-grapheme? key
  $process-goto-dialog:real-grapheme: {
    compare print?, 0/false
    break-if-=
    var fn-name/eax: (addr word) <- lookup *fn-name-ah
    add-grapheme-to-word fn-name, key
    return
  }
  # silently ignore other hotkeys
}

fn process-function _self: (addr environment), _function: (addr function), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var function/edi: (addr function) <- copy _function
  process-function-edit self, function, key
}

fn process-function-edit _self: (addr environment), _function: (addr function), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var function/edi: (addr function) <- copy _function
  var cursor-word-ah/ebx: (addr handle word) <- get function, cursor-word
  var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
  var cursor-word/ecx: (addr word) <- copy _cursor-word
  compare key, 0x445b1b/left-arrow
  $process-function-edit:key-left-arrow: {
    break-if-!=
#?     print-string 0, "left-arrow\n"
    # if not at start, move left within current word
    var at-start?/eax: boolean <- cursor-at-start? cursor-word
    compare at-start?, 0/false
    {
      break-if-!=
#?       print-string 0, "cursor left within word\n"
      cursor-left cursor-word
      return
    }
    # otherwise move to end of previous word
    var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
#?       print-string 0, "move to previous word\n"
      cursor-to-end prev-word
      copy-object prev-word-ah, cursor-word-ah
    }
    return
  }
  compare key, 0x435b1b/right-arrow
  $process-function-edit:key-right-arrow: {
    break-if-!=
    # if not at end, move right within current word
    var at-end?/eax: boolean <- cursor-at-end? cursor-word
    compare at-end?, 0/false
    {
      break-if-!=
      cursor-right cursor-word
      return
    }
    # otherwise, move to the next word
    var next-word-ah/edx: (addr handle word) <- get cursor-word, next
    var next-word/eax: (addr word) <- lookup *next-word-ah
    {
      compare next-word, 0
      break-if-=
      cursor-to-start next-word
      copy-object next-word-ah, cursor-word-ah
    }
    return
  }
  # word-based motions
  compare key, 2/ctrl-b
  $process-function-edit:prev-word: {
    break-if-!=
    # jump to previous word if possible
    var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
      cursor-to-end prev-word
      copy-object prev-word-ah, cursor-word-ah
    }
    return
  }
  compare key, 6/ctrl-f
  $process-function-edit:next-word: {
    break-if-!=
    # jump to previous word if possible
    var next-word-ah/edx: (addr handle word) <- get cursor-word, next
    var next-word/eax: (addr word) <- lookup *next-word-ah
    {
      compare next-word, 0
      break-if-=
      cursor-to-end next-word
      copy-object next-word-ah, cursor-word-ah
    }
    return
  }
  # line-based motions
  compare key, 1/ctrl-a
  $process-function-edit:start-of-line: {
    break-if-!=
    # move cursor to start of first word
    var body-ah/eax: (addr handle line) <- get function, body
    var body/eax: (addr line) <- lookup *body-ah
    var body-contents-ah/ecx: (addr handle word) <- get body, data
    copy-object body-contents-ah, cursor-word-ah
    var body-contents/eax: (addr word) <- lookup *body-contents-ah
    cursor-to-start body-contents
    return
  }
  compare key, 5/ctrl-e
  $process-function-edit:end-of-line: {
    break-if-!=
    # move cursor to end of final word
    var body-ah/eax: (addr handle line) <- get function, body
    var body/eax: (addr line) <- lookup *body-ah
    var body-contents-ah/ecx: (addr handle word) <- get body, data
    copy-object body-contents-ah, cursor-word-ah
    final-word cursor-word-ah, cursor-word-ah
    var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
    cursor-to-end cursor-word
    return
  }
  # bounce to another function
  compare key, 7/ctrl-g
  $process-function-edit:goto-function: {
    break-if-!=
    # initialize dialog to name function to jump to
    var partial-function-name-ah/eax: (addr handle word) <- get self, partial-function-name
    allocate partial-function-name-ah
    var partial-function-name/eax: (addr word) <- lookup *partial-function-name-ah
    initialize-word partial-function-name
    return
  }
  # bounce to sandbox
  compare key, 9/tab
  $process-function-edit:goto-sandbox: {
    break-if-!=
    var function-ah/eax: (addr handle function) <- get self, cursor-function
    clear-object function-ah
    return
  }
  # editing the current function
  compare key, 0x7f/del  # backspace on Macs
  $process-function-edit:backspace: {
    break-if-!=
    # if not at start of some word, delete grapheme before cursor within current word
    var at-start?/eax: boolean <- cursor-at-start? cursor-word
    compare at-start?, 0/false
    {
      break-if-!=
      delete-before-cursor cursor-word
      return
    }
    # otherwise delete current word and move to end of prev word
    var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
      cursor-to-end prev-word
      delete-next prev-word
      copy-object prev-word-ah, cursor-word-ah
    }
    return
  }
  compare key, 0x20/space
  $process-function-edit:space: {
    break-if-!=
#?     print-string 0, "space\n"
    # if cursor is at start of word, insert word before
    {
      var at-start?/eax: boolean <- cursor-at-start? cursor-word
      compare at-start?, 0/false
      break-if-=
      var prev-word-ah/eax: (addr handle word) <- get cursor-word, prev
      append-word prev-word-ah
      var new-prev-word-ah/eax: (addr handle word) <- get cursor-word, prev
      copy-object new-prev-word-ah, cursor-word-ah
      return
    }
    # if start of word is quote and grapheme before cursor is not, just insert it as usual
    # TODO: support string escaping
    {
      var first-grapheme/eax: grapheme <- first-grapheme cursor-word
      compare first-grapheme, 0x22/double-quote
      break-if-!=
      var final-grapheme/eax: grapheme <- grapheme-before-cursor cursor-word
      compare final-grapheme, 0x22/double-quote
      break-if-=
      break $process-function-edit:space
    }
    # if start of word is '[' and grapheme before cursor is not ']', just insert it as usual
    # TODO: support nested arrays
    {
      var first-grapheme/eax: grapheme <- first-grapheme cursor-word
      compare first-grapheme, 0x5b/[
      break-if-!=
      var final-grapheme/eax: grapheme <- grapheme-before-cursor cursor-word
      compare final-grapheme, 0x5d/]
      break-if-=
      break $process-function-edit:space
    }
    # otherwise insert word after and move cursor to it for the next key
    # (but we'll continue to track the current cursor-word for the rest of this function)
    append-word cursor-word-ah
    var next-word-ah/eax: (addr handle word) <- get cursor-word, next
    copy-object next-word-ah, cursor-word-ah
    # if cursor is at end of word, that's all
    var at-end?/eax: boolean <- cursor-at-end? cursor-word
    compare at-end?, 0/false
    {
      break-if-=
      return
    }
    # otherwise we're in the middle of a word
    # move everything after cursor to the (just created) next word
    var next-word-ah/eax: (addr handle word) <- get cursor-word, next
    var _next-word/eax: (addr word) <- lookup *next-word-ah
    var next-word/ebx: (addr word) <- copy _next-word
    {
      var at-end?/eax: boolean <- cursor-at-end? cursor-word
      compare at-end?, 0/false
      break-if-!=
      var g/eax: grapheme <- pop-after-cursor cursor-word
      add-grapheme-to-word next-word, g
      loop
    }
    cursor-to-start next-word
    return
  }
  # otherwise insert key within current word
  var g/edx: grapheme <- copy key
  var print?/eax: boolean <- real-grapheme? key
  $process-function-edit:real-grapheme: {
    compare print?, 0/false
    break-if-=
    add-grapheme-to-word cursor-word, g
    return
  }
  # silently ignore other hotkeys
}

fn process-sandbox _self: (addr environment), _sandbox: (addr sandbox), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var sandbox/edi: (addr sandbox) <- copy _sandbox
  var rename-word-mode-ah?/ecx: (addr handle word) <- get sandbox, partial-name-for-cursor-word
  var rename-word-mode?/eax: (addr word) <- lookup *rename-word-mode-ah?
  compare rename-word-mode?, 0
  {
    break-if-=
#?     print-string 0, "processing sandbox rename\n"
    process-sandbox-rename sandbox, key
    return
  }
  var define-function-mode-ah?/ecx: (addr handle word) <- get sandbox, partial-name-for-function
  var define-function-mode?/eax: (addr word) <- lookup *define-function-mode-ah?
  compare define-function-mode?, 0
  {
    break-if-=
#?     print-string 0, "processing function definition\n"
    var functions/ecx: (addr handle function) <- get self, functions
    process-sandbox-define sandbox, functions, key
    return
  }
#?   print-string 0, "processing sandbox edit\n"
  process-sandbox-edit self, sandbox, key
}

fn process-sandbox-edit _self: (addr environment), _sandbox: (addr sandbox), key: grapheme {
  var self/esi: (addr environment) <- copy _self
  var sandbox/edi: (addr sandbox) <- copy _sandbox
  var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
  var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
  var cursor-word-ah/ebx: (addr handle word) <- get cursor-call-path, word
  var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
  var cursor-word/ecx: (addr word) <- copy _cursor-word
  compare key, 0x445b1b/left-arrow
  $process-sandbox-edit:key-left-arrow: {
    break-if-!=
#?     print-string 0, "left-arrow\n"
    # if not at start, move left within current word
    var at-start?/eax: boolean <- cursor-at-start? cursor-word
    compare at-start?, 0/false
    {
      break-if-!=
#?       print-string 0, "cursor left within word\n"
      cursor-left cursor-word
      return
    }
    # if current word is expanded, move to the rightmost word in its body
    {
      var cursor-call-path/esi: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var expanded-words/edx: (addr handle call-path) <- get sandbox, expanded-words
      var curr-word-is-expanded?/eax: boolean <- find-in-call-paths expanded-words, cursor-call-path
      compare curr-word-is-expanded?, 0/false
      break-if-=
      # update cursor-call-path
#?       print-string 0, "curr word is expanded\n"
      var self/ecx: (addr environment) <- copy _self
      var functions/ecx: (addr handle function) <- get self, functions
      var body: (handle line)
      var body-ah/eax: (addr handle line) <- address body
      function-body functions, cursor-word-ah, body-ah
      var body-addr/eax: (addr line) <- lookup *body-ah
      var first-word-ah/edx: (addr handle word) <- get body-addr, data
      var final-word-h: (handle word)
      var final-word-ah/eax: (addr handle word) <- address final-word-h
      final-word first-word-ah, final-word-ah
      push-to-call-path-element cursor-call-path, final-word-ah
      # move cursor to end of word
      var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
      var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
      var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
      cursor-to-end cursor-word
      return
    }
    # if at first word, look for a caller to jump to
    $process-sandbox-edit:key-left-arrow-first-word: {
      var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
      var prev-word/eax: (addr word) <- lookup *prev-word-ah
      compare prev-word, 0
      break-if-!=
      $process-sandbox-edit:key-left-arrow-first-word-and-caller: {
#?         print-string 0, "return\n"
        {
          var cursor-call-path-ah/edi: (addr handle call-path-element) <- get sandbox, cursor-call-path
          var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
          var next-cursor-element-ah/edx: (addr handle call-path-element) <- get cursor-call-path, next
          var next-cursor-element/eax: (addr call-path-element) <- lookup *next-cursor-element-ah
          compare next-cursor-element, 0
          break-if-= $process-sandbox-edit:key-left-arrow-first-word-and-caller
          copy-object next-cursor-element-ah, cursor-call-path-ah
        }
        var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
        var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
        var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
        var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
        cursor-word <- copy _cursor-word
      }
    }
    # then move to end of previous word
    var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
#?       print-string 0, "move to previous word\n"
      cursor-to-end prev-word
#?       {
#?         var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
#?         var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
#?         var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
#?         var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
#?         var cursor-word/ebx: (addr word) <- copy _cursor-word
#?         print-string 0, "word at cursor before: "
#?         print-word 0, cursor-word
#?         print-string 0, "\n"
#?       }
      var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      decrement-final-element cursor-call-path
#?       {
#?         var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
#?         var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
#?         var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
#?         var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
#?         var cursor-word/ebx: (addr word) <- copy _cursor-word
#?         print-string 0, "word at cursor after: "
#?         print-word 0, cursor-word
#?         print-string 0, "\n"
#?       }
    }
    return
  }
  compare key, 0x435b1b/right-arrow
  $process-sandbox-edit:key-right-arrow: {
    break-if-!=
    # if not at end, move right within current word
    var at-end?/eax: boolean <- cursor-at-end? cursor-word
    compare at-end?, 0/false
    {
      break-if-!=
#?       print-string 0, "a\n"
      cursor-right cursor-word
      return
    }
    # if at final word, look for a caller to jump to
    {
      var next-word-ah/edx: (addr handle word) <- get cursor-word, next
      var next-word/eax: (addr word) <- lookup *next-word-ah
      compare next-word, 0
      break-if-!=
      var cursor-call-path-ah/edi: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
      var next-cursor-element-ah/ecx: (addr handle call-path-element) <- get cursor-call-path, next
      var next-cursor-element/eax: (addr call-path-element) <- lookup *next-cursor-element-ah
      compare next-cursor-element, 0
      break-if-=
      copy-object next-cursor-element-ah, cursor-call-path-ah
      return
    }
    # otherwise, move to the next word
    var next-word-ah/edx: (addr handle word) <- get cursor-word, next
    var next-word/eax: (addr word) <- lookup *next-word-ah
    {
      compare next-word, 0
      break-if-=
#?       print-string 0, "b\n"
      cursor-to-start next-word
      # . . cursor-word now out of date
      var cursor-call-path/ecx: (addr handle call-path-element) <- get sandbox, cursor-call-path
      increment-final-element cursor-call-path
      # Is the new cursor word expanded? If so, it's a function call. Add a
      # new level to the cursor-call-path for the call's body.
      $process-sandbox-edit:key-right-arrow-next-word-is-call-expanded: {
#?         print-string 0, "c\n"
        {
          var expanded-words/eax: (addr handle call-path) <- get sandbox, expanded-words
          var curr-word-is-expanded?/eax: boolean <- find-in-call-paths expanded-words, cursor-call-path
          compare curr-word-is-expanded?, 0/false
          break-if-= $process-sandbox-edit:key-right-arrow-next-word-is-call-expanded
        }
        var callee-h: (handle function)
        var callee-ah/edx: (addr handle function) <- address callee-h
        var functions/ebx: (addr handle function) <- get self, functions
        callee functions, next-word, callee-ah
        var callee/eax: (addr function) <- lookup *callee-ah
        var callee-body-ah/eax: (addr handle line) <- get callee, body
        var callee-body/eax: (addr line) <- lookup *callee-body-ah
        var callee-body-first-word/edx: (addr handle word) <- get callee-body, data
        push-to-call-path-element cursor-call-path, callee-body-first-word
        # position cursor at left
        var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
        var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
        var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
        var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
        cursor-to-start cursor-word
#?         print-string 0, "d\n"
        return
      }
    }
    return
  }
  compare key, 0xa/enter
  {
    break-if-!=
    # toggle display of subsidiary stack
    toggle-cursor-word sandbox
    return
  }
  compare key, 0xc/ctrl-l
  $process-sandbox-edit:new-line: {
    break-if-!=
    # new line in sandbox
    append-line sandbox
    return
  }
  # word-based motions
  compare key, 2/ctrl-b
  $process-sandbox-edit:prev-word: {
    break-if-!=
    # jump to previous word at same level
    var prev-word-ah/edx: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
      cursor-to-end prev-word
      var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      decrement-final-element cursor-call-path
      return
    }
    # if previous word doesn't exist, try to bump up one level
    {
      var cursor-call-path-ah/edi: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
      var caller-cursor-element-ah/ecx: (addr handle call-path-element) <- get cursor-call-path, next
      var caller-cursor-element/eax: (addr call-path-element) <- lookup *caller-cursor-element-ah
      compare caller-cursor-element, 0
      break-if-=
      # check if previous word exists in caller
      var caller-word-ah/eax: (addr handle word) <- get caller-cursor-element, word
      var caller-word/eax: (addr word) <- lookup *caller-word-ah
      var word-before-caller-ah/eax: (addr handle word) <- get caller-word, prev
      var word-before-caller/eax: (addr word) <- lookup *word-before-caller-ah
      compare word-before-caller, 0
      break-if-=
      # if so jump to it
      drop-from-call-path-element cursor-call-path-ah
      decrement-final-element cursor-call-path-ah
      return
    }
  }
  compare key, 6/ctrl-f
  $process-sandbox-edit:next-word: {
    break-if-!=
#?     print-string 0, "AA\n"
    # jump to previous word at same level
    var next-word-ah/edx: (addr handle word) <- get cursor-word, next
    var next-word/eax: (addr word) <- lookup *next-word-ah
    {
      compare next-word, 0
      break-if-=
#?       print-string 0, "BB\n"
      cursor-to-end next-word
      var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      increment-final-element cursor-call-path
      return
    }
    # if next word doesn't exist, try to bump up one level
#?     print-string 0, "CC\n"
    var cursor-call-path-ah/edi: (addr handle call-path-element) <- get sandbox, cursor-call-path
    var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
    var caller-cursor-element-ah/ecx: (addr handle call-path-element) <- get cursor-call-path, next
    var caller-cursor-element/eax: (addr call-path-element) <- lookup *caller-cursor-element-ah
    compare caller-cursor-element, 0
    break-if-=
#?     print-string 0, "DD\n"
    copy-object caller-cursor-element-ah, cursor-call-path-ah
    return
  }
  compare key, 7/ctrl-g
  $process-sandbox-edit:goto-function: {
    break-if-!=
    # initialize dialog to name function to jump to
    var partial-function-name-ah/eax: (addr handle word) <- get self, partial-function-name
    allocate partial-function-name-ah
    var partial-function-name/eax: (addr word) <- lookup *partial-function-name-ah
    initialize-word partial-function-name
    return
  }
  # line-based motions
  compare key, 1/ctrl-a
  $process-sandbox-edit:start-of-line: {
    break-if-!=
    # move cursor up past all calls and to start of line
    var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
    drop-nested-calls cursor-call-path-ah
    move-final-element-to-start-of-line cursor-call-path-ah
    # move cursor to start of word
    var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
    var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
    var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
    cursor-to-start cursor-word
    # this works as long as the first word isn't expanded
    # but we don't expect to see zero-arg functions first-up
    return
  }
  compare key, 5/ctrl-e
  $process-sandbox-edit:end-of-line: {
    break-if-!=
    # move cursor up past all calls and to start of line
    var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
    drop-nested-calls cursor-call-path-ah
    move-final-element-to-end-of-line cursor-call-path-ah
    # move cursor to end of word
    var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
    var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
    var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
    cursor-to-end cursor-word
    # this works because expanded words lie to the right of their bodies
    # so the final word is always guaranteed to be at the top-level
    return
  }
  compare key, 0x15/ctrl-u
  $process-sandbox-edit:clear-line: {
    break-if-!=
    # clear line in sandbox
    initialize-sandbox sandbox
    return
  }
  # if cursor is within a call, disable editing hotkeys below
  var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
  var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
  var next-cursor-element-ah/eax: (addr handle call-path-element) <- get cursor-call-path, next
  var next-cursor-element/eax: (addr call-path-element) <- lookup *next-cursor-element-ah
  compare next-cursor-element, 0
  {
    break-if-=
    return
  }
  # - remaining keys only work at the top row outside any function calls
  compare key, 0x7f/del  # backspace on Macs
  $process-sandbox-edit:backspace: {
    break-if-!=
    # if not at start of some word, delete grapheme before cursor within current word
    var at-start?/eax: boolean <- cursor-at-start? cursor-word
    compare at-start?, 0/false
    {
      break-if-!=
      delete-before-cursor cursor-word
      return
    }
    # otherwise delete current word and move to end of prev word
    var prev-word-ah/eax: (addr handle word) <- get cursor-word, prev
    var prev-word/eax: (addr word) <- lookup *prev-word-ah
    {
      compare prev-word, 0
      break-if-=
      cursor-to-end prev-word
      delete-next prev-word
      var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      decrement-final-element cursor-call-path
    }
    return
  }
  compare key, 0x20/space
  $process-sandbox-edit:space: {
    break-if-!=
#?     print-string 0, "space\n"
    # if cursor is at start of word, insert word before
    {
      var at-start?/eax: boolean <- cursor-at-start? cursor-word
      compare at-start?, 0/false
      break-if-=
      var prev-word-ah/eax: (addr handle word) <- get cursor-word, prev
      append-word prev-word-ah
      var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      decrement-final-element cursor-call-path
      return
    }
    # if start of word is quote and grapheme before cursor is not, just insert it as usual
    # TODO: support string escaping
    {
      var first-grapheme/eax: grapheme <- first-grapheme cursor-word
      compare first-grapheme, 0x22/double-quote
      break-if-!=
      var final-grapheme/eax: grapheme <- grapheme-before-cursor cursor-word
      compare final-grapheme, 0x22/double-quote
      break-if-=
      break $process-sandbox-edit:space
    }
    # if start of word is '[' and grapheme before cursor is not ']', just insert it as usual
    # TODO: support nested arrays
    {
      var first-grapheme/eax: grapheme <- first-grapheme cursor-word
      compare first-grapheme, 0x5b/[
      break-if-!=
      var final-grapheme/eax: grapheme <- grapheme-before-cursor cursor-word
      compare final-grapheme, 0x5d/]
      break-if-=
      break $process-sandbox-edit:space
    }
    # otherwise insert word after and move cursor to it for the next key
    # (but we'll continue to track the current cursor-word for the rest of this function)
    append-word cursor-word-ah
    var cursor-call-path/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
    increment-final-element cursor-call-path
    # if cursor is at end of word, that's all
    var at-end?/eax: boolean <- cursor-at-end? cursor-word
    compare at-end?, 0/false
    {
      break-if-=
      return
    }
    # otherwise we're in the middle of a word
    # move everything after cursor to the (just created) next word
    var next-word-ah/eax: (addr handle word) <- get cursor-word, next
    var _next-word/eax: (addr word) <- lookup *next-word-ah
    var next-word/ebx: (addr word) <- copy _next-word
    {
      var at-end?/eax: boolean <- cursor-at-end? cursor-word
      compare at-end?, 0/false
      break-if-!=
      var g/eax: grapheme <- pop-after-cursor cursor-word
      add-grapheme-to-word next-word, g
      loop
    }
    cursor-to-start next-word
    return
  }
  compare key, 0xe/ctrl-n
  $process:rename-word: {
    break-if-!=
    # TODO: ensure current word is not a function
    # rename word at cursor
    var new-name-ah/eax: (addr handle word) <- get sandbox, partial-name-for-cursor-word
    allocate new-name-ah
    var new-name/eax: (addr word) <- lookup *new-name-ah
    initialize-word new-name
    return
  }
  compare key, 4/ctrl-d
  $process:define-function: {
    break-if-!=
    # define function out of line at cursor
    var new-name-ah/eax: (addr handle word) <- get sandbox, partial-name-for-function
    allocate new-name-ah
    var new-name/eax: (addr word) <- lookup *new-name-ah
    initialize-word new-name
    return
  }
  # otherwise insert key within current word
  var g/edx: grapheme <- copy key
  var print?/eax: boolean <- real-grapheme? key
  $process-sandbox-edit:real-grapheme: {
    compare print?, 0/false
    break-if-=
    add-grapheme-to-word cursor-word, g
    return
  }
  # silently ignore other hotkeys
}

# collect new name in partial-name-for-cursor-word, and then rename the word
# at cursor to it
# Precondition: cursor-call-path is a singleton (not within a call)
fn process-sandbox-rename _sandbox: (addr sandbox), key: grapheme {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var new-name-ah/edi: (addr handle word) <- get sandbox, partial-name-for-cursor-word
  # if 'esc' pressed, cancel rename
  compare key, 0x1b/esc
  $process-sandbox-rename:cancel: {
    break-if-!=
    clear-object new-name-ah
    return
  }
  # if 'enter' pressed, perform rename
  compare key, 0xa/enter
  $process-sandbox-rename:commit: {
    break-if-!=
#?     print-string 0, "rename\n"
    # new line
    var new-line-h: (handle line)
    var new-line-ah/eax: (addr handle line) <- address new-line-h
    allocate new-line-ah
    var new-line/eax: (addr line) <- lookup *new-line-ah
    initialize-line new-line
    var new-line-word-ah/ecx: (addr handle word) <- get new-line, data
    {
      # move word at cursor to new line
      var cursor-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var cursor/eax: (addr call-path-element) <- lookup *cursor-ah
      var word-at-cursor-ah/eax: (addr handle word) <- get cursor, word
#?       print-string 0, "cursor before at word "
#?       {
#?         var cursor-word/eax: (addr word) <- lookup *word-at-cursor-ah
#?         print-word 0, cursor-word
#?         print-string 0, "\n"
#?       }
      move-word-contents word-at-cursor-ah, new-line-word-ah
      # copy name to word at cursor
      copy-word-contents-before-cursor new-name-ah, word-at-cursor-ah
#?       print-string 0, "cursor after at word "
#?       {
#?         var cursor-word/eax: (addr word) <- lookup *word-at-cursor-ah
#?         print-word 0, cursor-word
#?         print-string 0, "\n"
#?         var foo/eax: int <- copy cursor-word
#?         print-int32-hex 0, foo
#?         print-string 0, "\n"
#?       }
#?       print-string 0, "new name word "
#?       {
#?         var new-name/eax: (addr word) <- lookup *new-name-ah
#?         print-word 0, new-name
#?         print-string 0, "\n"
#?         var foo/eax: int <- copy new-name
#?         print-int32-hex 0, foo
#?         print-string 0, "\n"
#?       }
    }
    # prepend '=' to name
    {
      var new-name/eax: (addr word) <- lookup *new-name-ah
      cursor-to-start new-name
      add-grapheme-to-word new-name, 0x3d/=
    }
    # append name to new line
    chain-words new-line-word-ah, new-name-ah
    # new-line->next = sandbox->data
    var new-line-next/ecx: (addr handle line) <- get new-line, next
    var sandbox-slot/edx: (addr handle line) <- get sandbox, data
    copy-object sandbox-slot, new-line-next
    # sandbox->data = new-line
    copy-handle new-line-h, sandbox-slot
    # clear partial-name-for-cursor-word
    clear-object new-name-ah
#?     var cursor-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
#?     var cursor/eax: (addr call-path-element) <- lookup *cursor-ah
#?     var word-at-cursor-ah/eax: (addr handle word) <- get cursor, word
#?     print-string 0, "cursor after rename: "
#?     {
#?       var cursor-word/eax: (addr word) <- lookup *word-at-cursor-ah
#?       print-word 0, cursor-word
#?       print-string 0, " -- "
#?       var foo/eax: int <- copy cursor-word
#?       print-int32-hex 0, foo
#?       print-string 0, "\n"
#?     }
    return
  }
  #
  compare key, 0x7f/del  # backspace on Macs
  $process-sandbox-rename:backspace: {
    break-if-!=
    # if not at start, delete grapheme before cursor
    var new-name/eax: (addr word) <- lookup *new-name-ah
    var at-start?/eax: boolean <- cursor-at-start? new-name
    compare at-start?, 0/false
    {
      break-if-!=
      var new-name/eax: (addr word) <- lookup *new-name-ah
      delete-before-cursor new-name
    }
    return
  }
  # otherwise insert key within current word
  var print?/eax: boolean <- real-grapheme? key
  $process-sandbox-rename:real-grapheme: {
    compare print?, 0/false
    break-if-=
    var new-name/eax: (addr word) <- lookup *new-name-ah
    add-grapheme-to-word new-name, key
    return
  }
  # silently ignore other hotkeys
}

# collect new name in partial-name-for-function, and then define the last line
# of the sandbox to be a new function with that name. Replace the last line
# with a call to the appropriate function.
# Precondition: cursor-call-path is a singleton (not within a call)
fn process-sandbox-define _sandbox: (addr sandbox), functions: (addr handle function), key: grapheme {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var new-name-ah/edi: (addr handle word) <- get sandbox, partial-name-for-function
  # if 'esc' pressed, cancel define
  compare key, 0x1b/esc
  $process-sandbox-define:cancel: {
    break-if-!=
    clear-object new-name-ah
    return
  }
  # if 'enter' pressed, perform define
  compare key, 0xa/enter
  $process-sandbox-define:commit: {
    break-if-!=
#?     print-string 0, "define\n"
    # create new function
    var new-function: (handle function)
    var new-function-ah/ecx: (addr handle function) <- address new-function
    allocate new-function-ah
    var _new-function/eax: (addr function) <- lookup *new-function-ah
    var new-function/ebx: (addr function) <- copy _new-function
    var dest/edx: (addr handle function) <- get new-function, next
    copy-object functions, dest
    copy-object new-function-ah, functions
    # set function name to new-name
    var new-name/eax: (addr word) <- lookup *new-name-ah
    var dest/edx: (addr handle array byte) <- get new-function, name
    word-to-string new-name, dest
    # move final line to body
    var body-ah/eax: (addr handle line) <- get new-function, body
    allocate body-ah
    var body/eax: (addr line) <- lookup *body-ah
    var body-contents/ecx: (addr handle word) <- get body, data
    var final-line-storage: (handle line)
    var final-line-ah/eax: (addr handle line) <- address final-line-storage
    final-line sandbox, final-line-ah
    var final-line/eax: (addr line) <- lookup *final-line-ah
    var final-line-contents/eax: (addr handle word) <- get final-line, data
    copy-object final-line-contents, body-contents
    var cursor-word-ah/ecx: (addr handle word) <- get new-function, cursor-word
    copy-object final-line-contents, cursor-word-ah
    {
      var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
      cursor-to-start cursor-word
    }
    #
    copy-unbound-words-to-args functions
    #
    var empty-word: (handle word)
    copy-handle empty-word, final-line-contents
    construct-call functions, final-line-contents
    # clear partial-name-for-function
    var empty-word: (handle word)
    copy-handle empty-word, new-name-ah
    # update cursor
    var final-line/eax: (addr line) <- lookup final-line-storage
    var cursor-call-path-ah/ecx: (addr handle call-path-element) <- get sandbox, cursor-call-path
    allocate cursor-call-path-ah  # leak
    initialize-path-from-line final-line, cursor-call-path-ah
    return
  }
  #
  compare key, 0x7f/del  # backspace on Macs
  $process-sandbox-define:backspace: {
    break-if-!=
    # if not at start, delete grapheme before cursor
    var new-name/eax: (addr word) <- lookup *new-name-ah
    var at-start?/eax: boolean <- cursor-at-start? new-name
    compare at-start?, 0/false
    {
      break-if-!=
      var new-name/eax: (addr word) <- lookup *new-name-ah
      delete-before-cursor new-name
    }
    return
  }
  # otherwise insert key within current word
  var print?/eax: boolean <- real-grapheme? key
  $process-sandbox-define:real-grapheme: {
    compare print?, 0/false
    break-if-=
    var new-name/eax: (addr word) <- lookup *new-name-ah
    add-grapheme-to-word new-name, key
    return
  }
  # silently ignore other hotkeys
}

# extract from the body of the first function in 'functions' all words that
# aren't defined in the rest of 'functions'. Prepend them in reverse order.
# Assumes function body is a single line for now.
fn copy-unbound-words-to-args _functions: (addr handle function) {
  # target
  var target-ah/eax: (addr handle function) <- copy _functions
  var _target/eax: (addr function) <- lookup *target-ah
  var target/esi: (addr function) <- copy _target
  var dest-ah/edi: (addr handle word) <- get target, args
  # next
  var functions-ah/edx: (addr handle function) <- get target, next
  # src
  var line-ah/eax: (addr handle line) <- get target, body
  var line/eax: (addr line) <- lookup *line-ah
  var curr-ah/eax: (addr handle word) <- get line, data
  var curr/eax: (addr word) <- lookup *curr-ah
  {
    compare curr, 0
    break-if-=
    $copy-unbound-words-to-args:loop-iter: {
      # is it a number?
      {
        var int?/eax: boolean <- word-is-decimal-integer? curr
        compare int?, 0/false
        break-if-!= $copy-unbound-words-to-args:loop-iter
      }
      # is it a pre-existing function?
      var bound?/ebx: boolean <- bound-function? curr, functions-ah
      compare bound?, 0/false
      break-if-!=
      # is it already bound as an arg?
      var dup?/ebx: boolean <- arg-exists? _functions, curr  # _functions = target-ah
      compare dup?, 0/false
      break-if-!= $copy-unbound-words-to-args:loop-iter
      # push copy of curr before dest-ah
      var rest-h: (handle word)
      var rest-ah/ecx: (addr handle word) <- address rest-h
      copy-object dest-ah, rest-ah
      copy-word curr, dest-ah
      chain-words dest-ah, rest-ah
    }
    var next-ah/ecx: (addr handle word) <- get curr, next
    curr <- lookup *next-ah
    loop
  }
}

fn bound-function? w: (addr word), functions-ah: (addr handle function) -> _/ebx: boolean {
  var result/ebx: boolean <- copy 1/true
  {
    ## numbers
    # if w == "+" return true
    var subresult/eax: boolean <- word-equal? w, "+"
    compare subresult, 0/false
    break-if-!=
    # if w == "-" return true
    subresult <- word-equal? w, "-"
    compare subresult, 0/false
    break-if-!=
    # if w == "*" return true
    subresult <- word-equal? w, "*"
    compare subresult, 0/false
    break-if-!=
    # if w == "/" return true
    subresult <- word-equal? w, "/"
    compare subresult, 0/false
    break-if-!=
    # if w == "sqrt" return true
    subresult <- word-equal? w, "sqrt"
    compare subresult, 0/false
    break-if-!=
    ## strings/arrays
    # if w == "len" return true
    subresult <- word-equal? w, "len"
    compare subresult, 0/false
    break-if-!=
    ## files
    # if w == "open" return true
    subresult <- word-equal? w, "open"
    compare subresult, 0/false
    break-if-!=
    # if w == "read" return true
    subresult <- word-equal? w, "read"
    compare subresult, 0/false
    break-if-!=
    # if w == "slurp" return true
    subresult <- word-equal? w, "slurp"
    compare subresult, 0/false
    break-if-!=
    # if w == "lines" return true
    subresult <- word-equal? w, "lines"
    compare subresult, 0/false
    break-if-!=
    ## screens
    # if w == "fake-screen" return true
    subresult <- word-equal? w, "fake-screen"
    compare subresult, 0/false
    break-if-!=
    # if w == "print" return true
    subresult <- word-equal? w, "print"
    compare subresult, 0/false
    break-if-!=
    # if w == "move" return true
    subresult <- word-equal? w, "move"
    compare subresult, 0/false
    break-if-!=
    # if w == "up" return true
    subresult <- word-equal? w, "up"
    compare subresult, 0/false
    break-if-!=
    # if w == "down" return true
    subresult <- word-equal? w, "down"
    compare subresult, 0/false
    break-if-!=
    # if w == "left" return true
    subresult <- word-equal? w, "left"
    compare subresult, 0/false
    break-if-!=
    # if w == "right" return true
    subresult <- word-equal? w, "right"
    compare subresult, 0/false
    break-if-!=
    ## hacks
    # if w == "dup" return true
    subresult <- word-equal? w, "dup"
    compare subresult, 0/false
    break-if-!=
    # if w == "swap" return true
    subresult <- word-equal? w, "swap"
    compare subresult, 0/false
    break-if-!=
    # return w in functions
    var out-h: (handle function)
    var out/eax: (addr handle function) <- address out-h
    callee functions-ah, w, out
    var found?/eax: (addr function) <- lookup *out
    result <- copy found?
  }
  return result
}

fn arg-exists? _f-ah: (addr handle function), arg: (addr word) -> _/ebx: boolean {
  var f-ah/eax: (addr handle function) <- copy _f-ah
  var f/eax: (addr function) <- lookup *f-ah
  var args-ah/eax: (addr handle word) <- get f, args
  var result/ebx: boolean <- word-exists? args-ah, arg
  return result
}

# construct a call to `f` with copies of exactly its args
fn construct-call _f-ah: (addr handle function), _dest-ah: (addr handle word) {
  var f-ah/eax: (addr handle function) <- copy _f-ah
  var _f/eax: (addr function) <- lookup *f-ah
  var f/esi: (addr function) <- copy _f
  # append args in reverse
  var args-ah/eax: (addr handle word) <- get f, args
  var dest-ah/edi: (addr handle word) <- copy _dest-ah
  copy-words-in-reverse args-ah, dest-ah
  # append name
  var name-ah/eax: (addr handle array byte) <- get f, name
  var name/eax: (addr array byte) <- lookup *name-ah
  append-word-at-end-with dest-ah, name
}

fn word-index _words: (addr handle word), _n: int, out: (addr handle word) {
  var n/ecx: int <- copy _n
  {
    compare n, 0
    break-if-!=
    copy-object _words, out
    return
  }
  var words-ah/eax: (addr handle word) <- copy _words
  var words/eax: (addr word) <- lookup *words-ah
  var next/eax: (addr handle word) <- get words, next
  n <- decrement
  word-index next, n, out
}

fn toggle-cursor-word _sandbox: (addr sandbox) {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var expanded-words/edi: (addr handle call-path) <- get sandbox, expanded-words
  var cursor-call-path/ecx: (addr handle call-path-element) <- get sandbox, cursor-call-path
#?   print-string 0, "cursor call path: "
#?   dump-call-path-element 0, cursor-call-path
#?   print-string 0, "expanded words:\n"
#?   dump-call-paths 0, expanded-words
  var already-expanded?/eax: boolean <- find-in-call-paths expanded-words, cursor-call-path
  compare already-expanded?, 0/false
  {
    break-if-!=
#?     print-string 0, "expand\n"
    # if not already-expanded, insert
    insert-in-call-path expanded-words cursor-call-path
#?     print-string 0, "expanded words now:\n"
#?     dump-call-paths 0, expanded-words
    return
  }
  {
    break-if-=
    # otherwise delete
    delete-in-call-path expanded-words cursor-call-path
  }
}

fn append-line _sandbox: (addr sandbox) {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var line-ah/ecx: (addr handle line) <- get sandbox, data
  {
    var line/eax: (addr line) <- lookup *line-ah
    var next-line-ah/edx: (addr handle line) <- get line, next
    var next-line/eax: (addr line) <- lookup *next-line-ah
    compare next-line, 0
    break-if-=
    line-ah <- copy next-line-ah
    loop
  }
  var line/eax: (addr line) <- lookup *line-ah
  var final-line-ah/edx: (addr handle line) <- get line, next
  allocate final-line-ah
  var final-line/eax: (addr line) <- lookup *final-line-ah
  initialize-line final-line
  var final-prev/eax: (addr handle line) <- get final-line, prev
  copy-object line-ah, final-prev
  # clear cursor
  var final-line/eax: (addr line) <- lookup *final-line-ah
  var word-ah/ecx: (addr handle word) <- get final-line, data
  var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
  var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
  var dest/eax: (addr handle word) <- get cursor-call-path, word
  copy-object word-ah, dest
}

#############
# Visualize
#############

fn evaluate-environment _env: (addr environment), stack: (addr value-stack) {
  var env/esi: (addr environment) <- copy _env
  # functions
  var functions/edx: (addr handle function) <- get env, functions
  # line
  var sandbox-ah/esi: (addr handle sandbox) <- get env, sandboxes
  var sandbox/eax: (addr sandbox) <- lookup *sandbox-ah
  var line-ah/eax: (addr handle line) <- get sandbox, data
  var _line/eax: (addr line) <- lookup *line-ah
  var line/esi: (addr line) <- copy _line
  evaluate functions, 0, line, 0, stack
}

fn render _env: (addr environment) {
#?   print-string 0, "== render\n"
  var env/esi: (addr environment) <- copy _env
  clear-canvas env
  # menu
  render-menu env
  # screen
  var screen-ah/eax: (addr handle screen) <- get env, screen
  var _screen/eax: (addr screen) <- lookup *screen-ah
  var screen/edi: (addr screen) <- copy _screen
  # functions
  var sep-col/eax: (addr int) <- get env, code-separator-col
  var functions/edx: (addr handle function) <- get env, functions
  render-functions screen, *sep-col, env
  # sandbox
  var repl-col/ecx: int <- copy *sep-col
  repl-col <- add 2/repl-margin-left
  var cursor-sandbox-ah/eax: (addr handle sandbox) <- get env, cursor-sandbox
  var cursor-sandbox/eax: (addr sandbox) <- lookup *cursor-sandbox-ah
  # bindings
  var bindings-storage: table
  var bindings/ebx: (addr table) <- address bindings-storage
  initialize-table bindings, 0x10
#?   print-string 0, "render-sandbox {\n"
  render-sandbox screen, functions, bindings, cursor-sandbox, 3, repl-col
#?   print-string 0, "render-sandbox }\n"
  # dialogs
  render-goto-dialog screen, env
  #
  position-cursor screen, env
}

# draw a wordstar-style cheatsheet of shortcuts on the bottom line of the screen
fn render-menu _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var cursor-function-ah/eax: (addr handle function) <- get env, cursor-function
  var cursor-function/eax: (addr function) <- lookup *cursor-function-ah
  {
    compare cursor-function, 0
    break-if-=
    render-function-menu env
    return
  }
  var cursor-sandbox-ah/eax: (addr handle sandbox) <- get env, cursor-sandbox
  var cursor-sandbox/eax: (addr sandbox) <- lookup *cursor-sandbox-ah
  {
    compare cursor-sandbox, 0
    break-if-=
    render-sandbox-menu env
    return
  }
}

# HACK: areas currently responsible for positioning their dialogs' cursors. So
# we just do nothing here if a dialog is up.
fn position-cursor screen: (addr screen), _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var goto-function-ah/eax: (addr handle word) <- get env, partial-function-name
  var goto-function/eax: (addr word) <- lookup *goto-function-ah
  {
    compare goto-function, 0
    break-if-=
    return
  }
  var cursor-function-ah/eax: (addr handle function) <- get env, cursor-function
  var cursor-function/eax: (addr function) <- lookup *cursor-function-ah
  {
    compare cursor-function, 0
    break-if-=
    var cursor-row/ecx: (addr int) <- get cursor-function, cursor-row
    var cursor-col/eax: (addr int) <- get cursor-function, cursor-col
    move-cursor screen, *cursor-row, *cursor-col
    return
  }
  var cursor-sandbox-ah/eax: (addr handle sandbox) <- get env, cursor-sandbox
  var cursor-sandbox/eax: (addr sandbox) <- lookup *cursor-sandbox-ah
  {
    compare cursor-sandbox, 0
    break-if-=
    # if in a dialog, return
    {
      var partial-word-rename-ah/eax: (addr handle word) <- get cursor-sandbox, partial-name-for-cursor-word
      var partial-word-rename/eax: (addr word) <- lookup *partial-word-rename-ah
      compare partial-word-rename, 0
      break-if-=
      return
    }
    {
      var partial-function-name-ah/eax: (addr handle word) <- get cursor-sandbox, partial-name-for-function
      var partial-function-name/eax: (addr word) <- lookup *partial-function-name-ah
      compare partial-function-name, 0
      break-if-=
      return
    }
    var cursor-row/ecx: (addr int) <- get cursor-sandbox, cursor-row
    var cursor-col/eax: (addr int) <- get cursor-sandbox, cursor-col
    move-cursor screen, *cursor-row, *cursor-col
  }
}

fn render-goto-dialog screen: (addr screen), _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var goto-function-mode-ah?/eax: (addr handle word) <- get env, partial-function-name
  var goto-function-mode?/eax: (addr word) <- lookup *goto-function-mode-ah?
  compare goto-function-mode?, 0/false
  break-if-=
  # clear a space for the dialog
  var top-row/ebx: int <- copy 3
  var bottom-row/edx: int <- copy 9
  var sep-col/eax: (addr int) <- get env, code-separator-col
  var left-col/ecx: int <- copy *sep-col
  left-col <- subtract 0x10
  var right-col/eax: int <- copy *sep-col
  right-col <- add 0x10
  clear-rect screen, top-row, left-col, bottom-row, right-col
  draw-box screen, top-row, left-col, bottom-row, right-col
  # render a little menu for the dialog
  var menu-row/eax: int <- copy bottom-row
  menu-row <- decrement
  var menu-col/edx: int <- copy left-col
  menu-col <- add 2
  move-cursor screen, menu-row, menu-col
  start-reverse-video screen
  print-string screen, " esc "
  reset-formatting screen
  print-string screen, " cancel  "
  start-reverse-video screen
  print-string screen, " enter "
  reset-formatting screen
  print-string screen, " jump  "
  # draw the word, positioned appropriately around the cursor
  var start-col/ecx: int <- copy left-col
  start-col <- increment
  move-cursor screen, 6, start-col  # cursor-row
  var word-ah?/edx: (addr handle word) <- get env, partial-function-name
  var word/eax: (addr word) <- lookup *word-ah?
  print-word screen, word
}

fn render-sandbox screen: (addr screen), functions: (addr handle function), bindings: (addr table), _sandbox: (addr sandbox), top-row: int, left-col: int {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  # line
  var curr-line-ah/eax: (addr handle line) <- get sandbox, data
  var _curr-line/eax: (addr line) <- lookup *curr-line-ah
  var curr-line/ecx: (addr line) <- copy _curr-line
  #
  var curr-row/edx: int <- copy top-row
  # cursor row, col
  var cursor-row-addr: (addr int)
  var tmp/eax: (addr int) <- get sandbox, cursor-row
  copy-to cursor-row-addr, tmp
  var cursor-col-addr: (addr int)
  tmp <- get sandbox, cursor-col
  copy-to cursor-col-addr, tmp
  # render all but final line without stack
#?   print-string 0, "render all but final line\n"
  {
    var next-line-ah/eax: (addr handle line) <- get curr-line, next
    var next-line/eax: (addr line) <- lookup *next-line-ah
    compare next-line, 0
    break-if-=
    {
      var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
      var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
      var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
      var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
      # it's enough to pass in the first word of the path, because if the path isn't a singleton the word is guaranteed to be unique
      render-line-without-stack screen, curr-line, curr-row, left-col, cursor-word, cursor-row-addr, cursor-col-addr
    }
    curr-line <- copy next-line
    curr-row <- add 2
    loop
  }
  #
  render-final-line-with-stack screen, functions, bindings, sandbox, curr-row, left-col, cursor-row-addr, cursor-col-addr
  # at most one of the following dialogs will be rendered
  render-rename-dialog screen, sandbox
  render-define-dialog screen, sandbox
}

fn render-final-line-with-stack screen: (addr screen), functions: (addr handle function), bindings: (addr table), _sandbox: (addr sandbox), top-row: int, left-col: int, cursor-row-addr: (addr int), cursor-col-addr: (addr int) {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  # expanded-words
  var expanded-words/edi: (addr handle call-path) <- get sandbox, expanded-words
  # cursor-word
  var cursor-call-path-ah/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
  var cursor-call-path/eax: (addr call-path-element) <- lookup *cursor-call-path-ah
  var cursor-word-ah/eax: (addr handle word) <- get cursor-call-path, word
  var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
  var cursor-word/ebx: (addr word) <- copy _cursor-word
#?   print-string 0, "word at cursor: "
#?   print-word 0, cursor-word
#?   print-string 0, "\n"
  # cursor-call-path
  var cursor-call-path: (addr handle call-path-element)
  {
    var src/eax: (addr handle call-path-element) <- get sandbox, cursor-call-path
    copy-to cursor-call-path, src
  }
  # first line
  var first-line-ah/eax: (addr handle line) <- get sandbox, data
  var _first-line/eax: (addr line) <- lookup *first-line-ah
  var first-line/edx: (addr line) <- copy _first-line
  # final line
  var final-line-storage: (handle line)
  var final-line-ah/eax: (addr handle line) <- address final-line-storage
  final-line sandbox, final-line-ah
  var final-line/eax: (addr line) <- lookup *final-line-ah
  # curr-path
  var curr-path-storage: (handle call-path-element)
  var curr-path/ecx: (addr handle call-path-element) <- address curr-path-storage
  allocate curr-path  # leak
  initialize-path-from-line final-line, curr-path
  #
  var dummy/ecx: int <- render-line screen, functions, bindings, first-line, final-line, expanded-words, top-row, left-col, curr-path, cursor-word, cursor-call-path, cursor-row-addr, cursor-col-addr
}

fn final-line _sandbox: (addr sandbox), out: (addr handle line) {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var curr-line-ah/ecx: (addr handle line) <- get sandbox, data
  {
    var curr-line/eax: (addr line) <- lookup *curr-line-ah
    var next-line-ah/edx: (addr handle line) <- get curr-line, next
    var next-line/eax: (addr line) <- lookup *next-line-ah
    compare next-line, 0
    break-if-=
    curr-line-ah <- copy next-line-ah
    loop
  }
  copy-object curr-line-ah, out
}

fn render-rename-dialog screen: (addr screen), _sandbox: (addr sandbox) {
  var sandbox/edi: (addr sandbox) <- copy _sandbox
  var rename-word-mode-ah?/ecx: (addr handle word) <- get sandbox, partial-name-for-cursor-word
  var rename-word-mode?/eax: (addr word) <- lookup *rename-word-mode-ah?
  compare rename-word-mode?, 0/false
  break-if-=
  # clear a space for the dialog
  var cursor-row/ebx: (addr int) <- get sandbox, cursor-row
  var top-row/eax: int <- copy *cursor-row
  top-row <- subtract 3
  var bottom-row/ecx: int <- copy *cursor-row
  bottom-row <- add 3
  var cursor-col/ebx: (addr int) <- get sandbox, cursor-col
  var left-col/edx: int <- copy *cursor-col
  left-col <- subtract 0x10
  var right-col/ebx: int <- copy *cursor-col
  right-col <- add 0x10
  clear-rect screen, top-row, left-col, bottom-row, right-col
  draw-box screen, top-row, left-col, bottom-row, right-col
  # render a little menu for the dialog
  var menu-row/ecx: int <- copy bottom-row
  menu-row <- decrement
  var menu-col/edx: int <- copy left-col
  menu-col <- add 2
  move-cursor screen, menu-row, menu-col
  start-reverse-video screen
  print-string screen, " esc "
  reset-formatting screen
  print-string screen, " cancel  "
  start-reverse-video screen
  print-string screen, " enter "
  reset-formatting screen
  print-string screen, " rename  "
  # draw the word, positioned appropriately around the cursor
  var cursor-col/ebx: (addr int) <- get sandbox, cursor-col
  var start-col/ecx: int <- copy *cursor-col
  var word-ah?/edx: (addr handle word) <- get sandbox, partial-name-for-cursor-word
  var word/eax: (addr word) <- lookup *word-ah?
  var cursor-index/eax: int <- cursor-index word
  start-col <- subtract cursor-index
  var cursor-row/ebx: (addr int) <- get sandbox, cursor-row
  move-cursor screen, *cursor-row, start-col
  var word/eax: (addr word) <- lookup *word-ah?
  print-word screen, word
}

fn render-define-dialog screen: (addr screen), _sandbox: (addr sandbox) {
  var sandbox/edi: (addr sandbox) <- copy _sandbox
  var define-function-mode-ah?/ecx: (addr handle word) <- get sandbox, partial-name-for-function
  var define-function-mode?/eax: (addr word) <- lookup *define-function-mode-ah?
  compare define-function-mode?, 0/false
  break-if-=
  # clear a space for the dialog
  var cursor-row/ebx: (addr int) <- get sandbox, cursor-row
  var top-row/eax: int <- copy *cursor-row
  top-row <- subtract 3
  var bottom-row/ecx: int <- copy *cursor-row
  bottom-row <- add 3
  var cursor-col/ebx: (addr int) <- get sandbox, cursor-col
  var left-col/edx: int <- copy *cursor-col
  left-col <- subtract 0x10
  var right-col/ebx: int <- copy *cursor-col
  right-col <- add 0x10
  clear-rect screen, top-row, left-col, bottom-row, right-col
  draw-box screen, top-row, left-col, bottom-row, right-col
  # render a little menu for the dialog
  var menu-row/ecx: int <- copy bottom-row
  menu-row <- decrement
  var menu-col/edx: int <- copy left-col
  menu-col <- add 2
  move-cursor screen, menu-row, menu-col
  start-reverse-video screen
  print-string screen, " esc "
  reset-formatting screen
  print-string screen, " cancel  "
  start-reverse-video screen
  print-string screen, " enter "
  reset-formatting screen
  print-string screen, " define  "
  # draw the word, positioned appropriately around the cursor
  var cursor-col/ebx: (addr int) <- get sandbox, cursor-col
  var start-col/ecx: int <- copy *cursor-col
  var word-ah?/edx: (addr handle word) <- get sandbox, partial-name-for-function
  var word/eax: (addr word) <- lookup *word-ah?
  var cursor-index/eax: int <- cursor-index word
  start-col <- subtract cursor-index
  var cursor-row/ebx: (addr int) <- get sandbox, cursor-row
  move-cursor screen, *cursor-row, start-col
  var word/eax: (addr word) <- lookup *word-ah?
  print-word screen, word
}

# Render just the words in 'line'.
fn render-line-without-stack screen: (addr screen), _line: (addr line), curr-row: int, left-col: int, cursor-word: (addr word), cursor-row-addr: (addr int), cursor-col-addr: (addr int) {
  # curr-word
  var line/eax: (addr line) <- copy _line
  var first-word-ah/eax: (addr handle word) <- get line, data
  var _curr-word/eax: (addr word) <- lookup *first-word-ah
  var curr-word/esi: (addr word) <- copy _curr-word
  #
  # loop-carried dependency
  var curr-col/ecx: int <- copy left-col
  #
  {
    compare curr-word, 0
    break-if-=
#?     print-string 0, "-- word in penultimate lines: "
#?     {
#?       var foo/eax: int <- copy curr-word
#?       print-int32-hex 0, foo
#?     }
#?     print-string 0, "\n"
    var old-col/edx: int <- copy curr-col
    move-cursor screen, curr-row, curr-col
    print-word screen, curr-word
    {
      var max-width/eax: int <- word-length curr-word
      curr-col <- add max-width
      curr-col <- add 1/margin-right
    }
    # cache cursor column if necessary
    {
      compare curr-word, cursor-word
      break-if-!=
#?       print-string 0, "Cursor at "
#?       print-int32-decimal 0, curr-row
#?       print-string 0, ", "
#?       print-int32-decimal 0, old-col
#?       print-string 0, "\n"
#?       print-string 0, "contents: "
#?       print-word 0, cursor-word
#?       print-string 0, "\n"
#?       {
#?         var foo/eax: int <- copy cursor-word
#?         print-int32-hex 0, foo
#?         print-string 0, "\n"
#?       }
      var dest/ecx: (addr int) <- copy cursor-row-addr
      var src/eax: int <- copy curr-row
      copy-to *dest, src
      dest <- copy cursor-col-addr
      copy-to *dest, old-col
      var cursor-index-in-word/eax: int <- cursor-index curr-word
      add-to *dest, cursor-index-in-word
    }
    # loop update
    var next-word-ah/edx: (addr handle word) <- get curr-word, next
    var _curr-word/eax: (addr word) <- lookup *next-word-ah
    curr-word <- copy _curr-word
    loop
  }
}

fn call-depth-at-cursor _sandbox: (addr sandbox) -> _/eax: int {
  var sandbox/esi: (addr sandbox) <- copy _sandbox
  var cursor-call-path/edi: (addr handle call-path-element) <- get sandbox, cursor-call-path
  var result/eax: int <- call-path-element-length cursor-call-path
  result <- add 2  # input-row - 1
  return result
}

fn call-path-element-length _x: (addr handle call-path-element) -> _/eax: int {
  var curr-ah/ecx: (addr handle call-path-element) <- copy _x
  var result/edi: int <- copy 0
  {
    var curr/eax: (addr call-path-element) <- lookup *curr-ah
    compare curr, 0
    break-if-=
    curr-ah <- get curr, next
    result <- increment
    loop
  }
  return result
}

# Render the line of words in line, along with the state of the stack under each word.
# Also render any expanded function calls using recursive calls.
#
# Along the way, compute the column the cursor should be positioned at (cursor-col-addr).
fn render-line screen: (addr screen), functions: (addr handle function), bindings: (addr table), first-line: (addr line), _line: (addr line), expanded-words: (addr handle call-path), top-row: int, left-col: int, curr-path: (addr handle call-path-element), cursor-word: (addr word), cursor-call-path: (addr handle call-path-element), cursor-row-addr: (addr int), cursor-col-addr: (addr int) -> _/ecx: int {
#?   print-string 0, "render-line\n"
#?   dump-table bindings
  # curr-word
  var line/esi: (addr line) <- copy _line
  var first-word-ah/eax: (addr handle word) <- get line, data
  var curr-word/eax: (addr word) <- lookup *first-word-ah
  #
  # loop-carried dependency
  var curr-col/ecx: int <- copy left-col
  #
  {
    compare curr-word, 0
    break-if-=
#?     print-string 0, "-- word "
#?     print-word 0, curr-word
#?     print-string 0, "\n"
    # if necessary, first render columns for subsidiary stack
    $render-line:subsidiary: {
      {
#?         print-string 0, "check sub\n"
        var display-subsidiary-stack?/eax: boolean <- find-in-call-paths expanded-words, curr-path
        compare display-subsidiary-stack?, 0/false
        break-if-= $render-line:subsidiary
      }
#?       print-string 0, "render subsidiary stack\n"
      # does function exist?
      var callee/edi: (addr function) <- copy 0
      {
        var callee-h: (handle function)
        var callee-ah/ecx: (addr handle function) <- address callee-h
        callee functions, curr-word, callee-ah
        var _callee/eax: (addr function) <- lookup *callee-ah
        callee <- copy _callee
        compare callee, 0
        break-if-= $render-line:subsidiary
      }
      move-cursor screen, top-row, curr-col
      start-color screen, 8, 7
      print-word screen, curr-word
      {
        var word-len/eax: int <- word-length curr-word
        curr-col <- add word-len
        curr-col <- add 2
        increment top-row
      }
      # obtain stack at call site
      var stack-storage: value-stack
      var stack/edx: (addr value-stack) <- address stack-storage
      initialize-value-stack stack, 0x10
      {
        var prev-word-ah/eax: (addr handle word) <- get curr-word, prev
        var prev-word/eax: (addr word) <- lookup *prev-word-ah
        compare prev-word, 0
        break-if-=
        var bindings2-storage: table
        var bindings2/ebx: (addr table) <- address bindings2-storage
        deep-copy-table bindings, bindings2
        evaluate functions, bindings2, first-line, prev-word, stack
      }
      # construct new bindings
      var callee-bindings-storage: table
      var callee-bindings/esi: (addr table) <- address callee-bindings-storage
      initialize-table callee-bindings, 0x10
      bind-args callee, stack, callee-bindings
      # obtain body
      var callee-body-ah/eax: (addr handle line) <- get callee, body
      var callee-body/eax: (addr line) <- lookup *callee-body-ah
      var callee-body-first-word/edx: (addr handle word) <- get callee-body, data
      # - render subsidiary stack
      push-to-call-path-element curr-path, callee-body-first-word  # leak
#?       print-string 0, "subsidiary {\n"
#?       dump-table callee-bindings
#?       syscall_exit
      curr-col <- render-line screen, functions, callee-bindings, callee-body, callee-body, expanded-words, top-row, curr-col, curr-path, cursor-word, cursor-call-path, cursor-row-addr, cursor-col-addr
#?       print-string 0, "}\n"
      drop-from-call-path-element curr-path
      #
      move-cursor screen, top-row, curr-col
      print-code-point screen, 0x21d7/      #
      curr-col <- add 2
      decrement top-row
    }
    # render main column
    var old-col/edx: int <- copy curr-col
    var bindings2-storage: table
    var bindings2/ebx: (addr table) <- address bindings2-storage
#?     print-string 0, "deep-copy {\n"
    deep-copy-table bindings, bindings2
#?     print-string 0, "}\n"
#?     print-string 0, "render column {\n"
    curr-col <- render-column screen, functions, bindings2, first-line, line, curr-word, top-row, curr-col
#?     print-string 0, "}\n"
    # cache cursor column if necessary
    $render-line:cache-cursor-column: {
      {
        var found?/eax: boolean <- call-path-element-match? curr-path, cursor-call-path
        compare found?, 0/false
        break-if-= $render-line:cache-cursor-column
      }
      var dest/edi: (addr int) <- copy cursor-row-addr
      {
        var src/eax: int <- copy top-row
        copy-to *dest, src
      }
      dest <- copy cursor-col-addr
      copy-to *dest, old-col
      var cursor-index-in-word/eax: int <- cursor-index curr-word
      add-to *dest, cursor-index-in-word
    }
    # loop update
#?     print-string 0, "next word\n"
    var next-word-ah/edx: (addr handle word) <- get curr-word, next
    curr-word <- lookup *next-word-ah
#?     {
#?       var foo/eax: int <- copy curr-word
#?       print-int32-hex 0, foo
#?       print-string 0, "\n"
#?     }
    increment-final-element curr-path
    loop
  }
  return curr-col
}

fn callee functions: (addr handle function), word: (addr word), out: (addr handle function) {
  var stream-storage: (stream byte 0x10)
  var stream/esi: (addr stream byte) <- address stream-storage
  emit-word word, stream
  find-function functions, stream, out
}

# Render:
#   - starting at top-row, left-col: final-word
#   - starting somewhere below at left-col: the stack result from interpreting first-world to final-word (inclusive)
#
# Return the farthest column written.
fn render-column screen: (addr screen), functions: (addr handle function), bindings: (addr table), first-line: (addr line), line: (addr line), final-word: (addr word), top-row: int, left-col: int -> _/ecx: int {
#?   print-string 0, "render-column\n"
#?   dump-table bindings
  var max-width/esi: int <- copy 0
  {
    # compute stack
    var stack: value-stack
    var stack-addr/edi: (addr value-stack) <- address stack
    initialize-value-stack stack-addr, 0x10/max-words
    # copy bindings
    var bindings2-storage: table
    var bindings2/ebx: (addr table) <- address bindings2-storage
#?     print-string 0, "deep copy table {\n"
    deep-copy-table bindings, bindings2
#?     print-string 0, "}\n"
    evaluate functions, bindings2, first-line, final-word, stack-addr
    # indent stack
    var indented-col/ebx: int <- copy left-col
    indented-col <- add 1/margin-right
    # render stack
    var curr-row/edx: int <- copy top-row
    curr-row <- add 2/stack-margin-top
    {
      var top-addr/ecx: (addr int) <- get stack-addr, top
      compare *top-addr, 0
      break-if-<=
      decrement *top-addr
      var data-ah/eax: (addr handle array value) <- get stack-addr, data
      var data/eax: (addr array value) <- lookup *data-ah
      var top/ecx: int <- copy *top-addr
      var dest-offset/ecx: (offset value) <- compute-offset data, top
      var val/eax: (addr value) <- index data, dest-offset
      render-value-at screen, curr-row, indented-col, val, 1/top-level=true
      {
        var width/eax: int <- value-width val, 1
        compare width, max-width
        break-if-<=
        max-width <- copy width
      }
      var height/eax: int <- value-height val
      curr-row <- add height
      loop
    }
  }

  max-width <- add 2  # spaces on either side of items on the stack

  # render word, initialize result
  reset-formatting screen
  move-cursor screen, top-row, left-col
  print-word screen, final-word
  {
    var width/eax: int <- word-length final-word
    compare width, max-width
    break-if-<=
    max-width <- copy width
  }

  # post-process right-col
  var right-col/ecx: int <- copy left-col
  right-col <- add max-width
  right-col <- add 1/margin-right
#?   print-int32-decimal 0, left-col
#?   print-string 0, " => "
#?   print-int32-decimal 0, right-col
#?   print-string 0, "\n"
  return right-col
}

fn render-function-menu _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var screen-ah/edi: (addr handle screen) <- get env, screen
  var _screen/eax: (addr screen) <- lookup *screen-ah
  var screen/edi: (addr screen) <- copy _screen
  var nrows/eax: (addr int) <- get env, nrows
  move-cursor screen, *nrows, 0
  start-reverse-video screen
  print-string screen, " ctrl-q "
  reset-formatting screen
  print-string screen, " quit     "
  start-reverse-video screen
  print-string screen, " ctrl-a "
  reset-formatting screen
  print-string screen, " ⏮   "
  start-reverse-video screen
  print-string screen, " ctrl-b "
  reset-formatting screen
  print-string screen, " ◀ word  "
  start-reverse-video screen
  print-string screen, " ctrl-f "
  reset-formatting screen
  print-string screen, " word ▶  "
  start-reverse-video screen
  print-string screen, " ctrl-e "
  reset-formatting screen
  print-string screen, " ⏭       "
  start-reverse-video screen
  print-string screen, " ctrl-g "
  reset-formatting screen
  print-string screen, " go to function  "
  start-reverse-video screen
  print-string screen, " tab "
  reset-formatting screen
  print-string screen, " go to sandbox"
}

fn render-sandbox-menu _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var screen-ah/edi: (addr handle screen) <- get env, screen
  var _screen/eax: (addr screen) <- lookup *screen-ah
  var screen/edi: (addr screen) <- copy _screen
  var nrows/eax: (addr int) <- get env, nrows
  move-cursor screen, *nrows, 0
  start-reverse-video screen
  print-string screen, " ctrl-q "
  reset-formatting screen
  print-string screen, " quit     "
  start-reverse-video screen
  print-string screen, " ctrl-a "
  reset-formatting screen
  print-string screen, " ⏮   "
  start-reverse-video screen
  print-string screen, " ctrl-b "
  reset-formatting screen
  print-string screen, " ◀ word  "
  start-reverse-video screen
  print-string screen, " ctrl-f "
  reset-formatting screen
  print-string screen, " word ▶  "
  start-reverse-video screen
  print-string screen, " ctrl-e "
  reset-formatting screen
  print-string screen, " ⏭       "
  start-reverse-video screen
  print-string screen, " ctrl-g "
  reset-formatting screen
  print-string screen, " go to function     "
  start-reverse-video screen
  print-string screen, " ctrl-l "
  reset-formatting screen
  print-string screen, " new line "
  start-reverse-video screen
  print-string screen, " ctrl-u "
  reset-formatting screen
  print-string screen, " clear  "
  start-reverse-video screen
  print-string screen, " ctrl-n "
  reset-formatting screen
  print-string screen, " name word  "
  start-reverse-video screen
  print-string screen, " ctrl-d "
  reset-formatting screen
  print-string screen, " define function"
}

fn clear-canvas _env: (addr environment) {
  var env/esi: (addr environment) <- copy _env
  var screen-ah/edi: (addr handle screen) <- get env, screen
  var _screen/eax: (addr screen) <- lookup *screen-ah
  var screen/edi: (addr screen) <- copy _screen
  clear-screen screen
  var nrows/eax: (addr int) <- get env, nrows
  var sep-col/ecx: (addr int) <- get env, code-separator-col
  # divider
  draw-vertical-line screen, 1, *nrows, *sep-col
  # primitives
  var dummy/eax: int <- render-primitives screen, *nrows, *sep-col
}

# return value: top-most row written to
fn render-primitives screen: (addr screen), bottom-margin-row: int, right-col: int -> _/eax: int {
  # render primitives from the bottom of the screen upward
  var row/ecx: int <- copy bottom-margin-row
  row <- subtract 1
  var col/edx: int <- copy 1
  move-cursor screen, row, col
  row, col <- render-primitive-group screen, row, col, right-col, "numbers: ", "+ - * / sqrt  "
  row, col <- render-primitive-group screen, row, col, right-col, "arrays: ", "len  "
  row, col <- render-primitive-group screen, row, col, right-col, "files: ", "open read slurp lines  "
  row, col <- render-primitive-group screen, row, col, right-col, "misc: ", "dup swap  "  # hack: keep these at the right of the bottom row
  row, col <- render-primitive-group screen, row, col, right-col, "screens: ", "fake-screen print move up down left right  "
  # finally print heading up top
  row <- decrement
  move-cursor screen, row, 1
  start-bold screen
  print-string screen, "primitives:"
  reset-formatting screen
  return row
}

# start at row, col and print the given strings
# move up one row if there isn't enough room before right-col
# return row, col printed until
fn render-primitive-group screen: (addr screen), _row: int, _col: int, right-col: int, _heading: (addr array byte), _contents: (addr array byte) -> _/ecx: int, _/edx: int {
  var row/ecx: int <- copy _row
  var col/edx: int <- copy _col
  # decrement row if necessary
  var new-col/ebx: int <- copy col
  var heading/esi: (addr array byte) <- copy _heading
  var len1/eax: int <- length heading
  new-col <- add len1
  var contents/edi: (addr array byte) <- copy _contents
  var len2/eax: int <- length contents
  new-col <- add len2
  var bound/eax: int <- copy right-col
  bound <- decrement
  {
    compare new-col, bound
    break-if-<=
    row <- decrement
    col <- copy 1
  }
  move-cursor screen, row, col
  start-color screen, 0xf6, 7
  print-string screen, heading
  reset-formatting screen
  print-string screen, contents
  return row, new-col
}

fn render-functions screen: (addr screen), right-col: int, _env: (addr environment) {
  var row/ecx: int <- copy 1
  var dummy-col/edx: int <- copy right-col
  var env/esi: (addr environment) <- copy _env
  var functions/esi: (addr handle function) <- get env, functions
  {
    var curr/eax: (addr function) <- lookup *functions
    compare curr, 0
    break-if-=
    row, dummy-col <- render-function-right-aligned screen, row, right-col, curr
    functions <- get curr, next
    row <- add 1/inter-function-margin
    loop
  }
}

# print function starting at row, right-aligned before right-col
# return row, col printed until
fn render-function-right-aligned screen: (addr screen), row: int, right-col: int, f: (addr function) -> _/ecx: int, _/edx: int {
  var col/edx: int <- copy right-col
  col <- subtract 1/function-right-margin
  var col2/ebx: int <- copy col
  var width/eax: int <- function-width f
  col <- subtract width
  var new-row/ecx: int <- copy row
  var height/eax: int <- function-height f
  new-row <- add height
  new-row <- decrement
  col <- subtract 1/function-left-padding
  start-color screen, 0, 0xf7
  clear-rect screen, row, col, new-row, col2
  col <- add 1
#?   var dummy/eax: grapheme <- read-key-from-real-keyboard
  render-function screen, row, col, f
  new-row <- add 1/function-bottom-margin
  col <- subtract 1/function-left-padding
  col <- subtract 1/function-left-margin
  reset-formatting screen
  return new-row, col
}

# render function starting at row, col
# only single-line functions supported for now
fn render-function screen: (addr screen), row: int, col: int, _f: (addr function) {
  var f/esi: (addr function) <- copy _f
  var args/ecx: (addr handle word) <- get f, args
  move-cursor screen, row, col
  print-words-in-reverse screen, args
  var name-ah/eax: (addr handle array byte) <- get f, name
  var name/eax: (addr array byte) <- lookup *name-ah
  start-bold screen
  print-string screen, name
  reset-formatting screen
  start-color screen, 0, 0xf7
  increment row
  add-to col, 2
  move-cursor screen, row, col
  print-string screen, "≡ "
  add-to col, 2
  var cursor-row/ecx: (addr int) <- get f, cursor-row
  var cursor-col/edx: (addr int) <- get f, cursor-col
  var cursor-word-ah/eax: (addr handle word) <- get f, cursor-word
  var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
  var cursor-word/ebx: (addr word) <- copy _cursor-word
  var body-ah/eax: (addr handle line) <- get f, body
  var body/eax: (addr line) <- lookup *body-ah
  render-line-without-stack screen, body, row, col, cursor-word, cursor-row, cursor-col
}

fn real-grapheme? g: grapheme -> _/eax: boolean {
  # if g == newline return true
  compare g, 0xa
  {
    break-if-!=
    return 1/true
  }
  # if g == tab return true
  compare g, 9
  {
    break-if-!=
    return 1/true
  }
  # if g < 32 return false
  compare g, 0x20
  {
    break-if->=
    return 0/false
  }
  # if g <= 255 return true
  compare g, 0xff
  {
    break-if->
    return 1/true
  }
  # if (g&0xff == Esc) it's an escape sequence
  and-with g, 0xff
  compare g, 0x1b/esc
  {
    break-if-!=
    return 0/false
  }
  # otherwise return true
  return 1/true
}