about summary refs log tree commit diff stats
path: root/html/edit/002-typing.mu.html
blob: a9f022204b5c92bf939cdc516bbfea723e54d4cb (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
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Mu - edit/002-typing.mu</title>
<meta name="Generator" content="Vim/7.4">
<meta name="plugin-version" content="vim7.4_v2">
<meta name="syntax" content="none">
<meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy=">
<meta name="colorscheme" content="minimal">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #eeeeee; background-color: #080808; }
body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color: #080808; }
* { font-size: 12pt; font-size: 1em; }
.muRecipe { color: #ff8700; }
.muData { color: #ffff00; }
.Special { color: #c00000; }
.muScenario { color: #00af00; }
.Delimiter { color: #800080; }
.Comment { color: #9090ff; }
.Constant { color: #00a0a0; }
.SalientComment { color: #00ffff; }
.muControl { color: #c0a020; }
-->
</style>

<script type='text/javascript'>
<!--

-->
</script>
</head>
<body>
<pre id='vimCodeElement'>
<span class="SalientComment">## handling events from the keyboard, mouse, touch screen, ...</span>

<span class="Comment"># temporary main: interactive editor</span>
<span class="Comment"># hit ctrl-c to exit</span>
<span class="muRecipe">def!</span> main text:address:array:character [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  open-console
  editor:address:editor-data<span class="Special"> &lt;- </span>new-editor text, <span class="Constant">0/screen</span>, <span class="Constant">5/left</span>, <span class="Constant">45/right</span>
  editor-event-loop <span class="Constant">0/screen</span>, <span class="Constant">0/console</span>, editor
  close-console
]

<span class="muRecipe">def</span> editor-event-loop screen:address:screen, console:address:console, editor:address:editor-data<span class="muRecipe"> -&gt; </span>screen:address:screen, console:address:console, editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># looping over each (keyboard or touch) event as it occurs</span>
<span class="Constant">    +next-event</span>
    cursor-row:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-row:offset</span>
    cursor-column:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-column:offset</span>
    screen<span class="Special"> &lt;- </span>move-cursor screen, cursor-row, cursor-column
    e:event, console:address:console, found?:boolean, quit?:boolean<span class="Special"> &lt;- </span>read-event console
    <span class="muControl">loop-unless</span> found?
    <span class="muControl">break-if</span> quit?  <span class="Comment"># only in tests</span>
    trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[next-event]</span>
    <span class="Comment"># 'touch' event</span>
    t:touch-event, is-touch?:boolean<span class="Special"> &lt;- </span>maybe-convert e, <span class="Constant">touch:variant</span>
    <span class="Delimiter">{</span>
      <span class="muControl">break-unless</span> is-touch?
      move-cursor-in-editor screen, editor, t
      <span class="muControl">loop</span> <span class="Constant">+next-event:label</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># keyboard events</span>
    <span class="Delimiter">{</span>
      <span class="muControl">break-if</span> is-touch?
      screen, editor, go-render?:boolean<span class="Special"> &lt;- </span>handle-keyboard-event screen, editor, e
      <span class="Delimiter">{</span>
        <span class="muControl">break-unless</span> go-render?
        screen<span class="Special"> &lt;- </span>editor-render screen, editor
      <span class="Delimiter">}</span>
    <span class="Delimiter">}</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="Comment"># process click, return if it was on current editor</span>
<span class="muRecipe">def</span> move-cursor-in-editor screen:address:screen, editor:address:editor-data, t:touch-event<span class="muRecipe"> -&gt; </span>in-focus?:boolean, editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="muControl">return-unless</span> editor, <span class="Constant">0/false</span>
  click-row:number<span class="Special"> &lt;- </span>get t, <span class="Constant">row:offset</span>
  <span class="muControl">return-unless</span> click-row, <span class="Constant">0/false</span>  <span class="Comment"># ignore clicks on 'menu'</span>
  click-column:number<span class="Special"> &lt;- </span>get t, <span class="Constant">column:offset</span>
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  too-far-left?:boolean<span class="Special"> &lt;- </span>lesser-than click-column, left
  <span class="muControl">return-if</span> too-far-left?, <span class="Constant">0/false</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  too-far-right?:boolean<span class="Special"> &lt;- </span>greater-than click-column, right
  <span class="muControl">return-if</span> too-far-right?, <span class="Constant">0/false</span>
  <span class="Comment"># position cursor</span>
<span class="Constant">  &lt;move-cursor-begin&gt;</span>
  editor<span class="Special"> &lt;- </span>snap-cursor screen, editor, click-row, click-column
  undo-coalesce-tag:number<span class="Special"> &lt;- </span>copy <span class="Constant">0/never</span>
<span class="Constant">  &lt;move-cursor-end&gt;</span>
  <span class="Comment"># gain focus</span>
  <span class="muControl">return</span> <span class="Constant">1/true</span>
]

<span class="Comment"># Variant of 'render' that only moves the cursor (coordinates and</span>
<span class="Comment"># before-cursor). If it's past the end of a line, it 'slides' it left. If it's</span>
<span class="Comment"># past the last line it positions at end of last line.</span>
<span class="muRecipe">def</span> snap-cursor screen:address:screen, editor:address:editor-data, target-row:number, target-column:number<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="muControl">return-unless</span> editor
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  <span class="Comment"># count newlines until screen row</span>
  curr:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">top-of-screen:offset</span>
  prev:address:duplex-list:character<span class="Special"> &lt;- </span>copy curr  <span class="Comment"># just in case curr becomes null and we can't compute prev</span>
  curr<span class="Special"> &lt;- </span>next curr
  row:number<span class="Special"> &lt;- </span>copy <span class="Constant">1/top</span>
  column:number<span class="Special"> &lt;- </span>copy left
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-row:offset</span>, target-row
  cursor-row:number<span class="Special"> &lt;- </span>copy target-row
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, target-column
  cursor-column:number<span class="Special"> &lt;- </span>copy target-column
  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
  <span class="Delimiter">{</span>
<span class="Constant">    +next-character</span>
    <span class="muControl">break-unless</span> curr
    off-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal row, screen-height
    <span class="muControl">break-if</span> off-screen?
    <span class="Comment"># update editor-data.before-cursor</span>
    <span class="Comment"># Doing so at the start of each iteration ensures it stays one step behind</span>
    <span class="Comment"># the current character.</span>
    <span class="Delimiter">{</span>
      at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, cursor-row
      <span class="muControl">break-unless</span> at-cursor-row?
      at-cursor?:boolean<span class="Special"> &lt;- </span>equal column, cursor-column
      <span class="muControl">break-unless</span> at-cursor?
      before-cursor<span class="Special"> &lt;- </span>copy prev
      *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">before-cursor:offset</span>, before-cursor
    <span class="Delimiter">}</span>
    c:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
    <span class="Delimiter">{</span>
      <span class="Comment"># newline? move to left rather than 0</span>
      newline?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
      <span class="muControl">break-unless</span> newline?
      <span class="Comment"># adjust cursor if necessary</span>
      <span class="Delimiter">{</span>
        at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, cursor-row
        <span class="muControl">break-unless</span> at-cursor-row?
        left-of-cursor?:boolean<span class="Special"> &lt;- </span>lesser-than column, cursor-column
        <span class="muControl">break-unless</span> left-of-cursor?
        cursor-column<span class="Special"> &lt;- </span>copy column
        *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, cursor-column
        before-cursor<span class="Special"> &lt;- </span>copy prev
        *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">before-cursor:offset</span>, before-cursor
      <span class="Delimiter">}</span>
      <span class="Comment"># skip to next line</span>
      row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
      column<span class="Special"> &lt;- </span>copy left
      curr<span class="Special"> &lt;- </span>next curr
      prev<span class="Special"> &lt;- </span>next prev
      <span class="muControl">loop</span> <span class="Constant">+next-character:label</span>
    <span class="Delimiter">}</span>
    <span class="Delimiter">{</span>
      <span class="Comment"># at right? wrap. even if there's only one more letter left; we need</span>
      <span class="Comment"># room for clicking on the cursor after it.</span>
      at-right?:boolean<span class="Special"> &lt;- </span>equal column, right
      <span class="muControl">break-unless</span> at-right?
      column<span class="Special"> &lt;- </span>copy left
      row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
      <span class="Comment"># don't increment curr/prev</span>
      <span class="muControl">loop</span> <span class="Constant">+next-character:label</span>
    <span class="Delimiter">}</span>
    curr<span class="Special"> &lt;- </span>next curr
    prev<span class="Special"> &lt;- </span>next prev
    column<span class="Special"> &lt;- </span>add column, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># is cursor to the right of the last line? move to end</span>
  <span class="Delimiter">{</span>
    at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, cursor-row
    cursor-outside-line?:boolean<span class="Special"> &lt;- </span>lesser-or-equal column, cursor-column
    before-cursor-on-same-line?:boolean<span class="Special"> &lt;- </span>and at-cursor-row?, cursor-outside-line?
    above-cursor-row?:boolean<span class="Special"> &lt;- </span>lesser-than row, cursor-row
    before-cursor?:boolean<span class="Special"> &lt;- </span>or before-cursor-on-same-line?, above-cursor-row?
    <span class="muControl">break-unless</span> before-cursor?
    cursor-row<span class="Special"> &lt;- </span>copy row
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-row:offset</span>, cursor-row
    cursor-column<span class="Special"> &lt;- </span>copy column
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, cursor-column
    before-cursor<span class="Special"> &lt;- </span>copy prev
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">before-cursor:offset</span>, before-cursor
  <span class="Delimiter">}</span>
]

<span class="Comment"># Process an event 'e' and try to minimally update the screen.</span>
<span class="Comment"># Set 'go-render?' to true to indicate the caller must perform a non-minimal update.</span>
<span class="muRecipe">def</span> handle-keyboard-event screen:address:screen, editor:address:editor-data, e:event<span class="muRecipe"> -&gt; </span>screen:address:screen, editor:address:editor-data, go-render?:boolean [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
  <span class="muControl">return-unless</span> editor
  screen-width:number<span class="Special"> &lt;- </span>screen-width screen
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
  cursor-row:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-row:offset</span>
  cursor-column:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-column:offset</span>
  save-row:number<span class="Special"> &lt;- </span>copy cursor-row
  save-column:number<span class="Special"> &lt;- </span>copy cursor-column
  <span class="Comment"># character</span>
  <span class="Delimiter">{</span>
    c:character, is-unicode?:boolean<span class="Special"> &lt;- </span>maybe-convert e, <span class="Constant">text:variant</span>
    <span class="muControl">break-unless</span> is-unicode?
    trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[handle-keyboard-event: special character]</span>
    <span class="Comment"># exceptions for special characters go here</span>
<span class="Constant">    &lt;handle-special-character&gt;</span>
    <span class="Comment"># ignore any other special characters</span>
    regular-character?:boolean<span class="Special"> &lt;- </span>greater-or-equal c, <span class="Constant">32/space</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
    <span class="muControl">return-unless</span> regular-character?
    <span class="Comment"># otherwise type it in</span>
<span class="Constant">    &lt;insert-character-begin&gt;</span>
    editor, screen, go-render?:boolean<span class="Special"> &lt;- </span>insert-at-cursor editor, c, screen
<span class="Constant">    &lt;insert-character-end&gt;</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># special key to modify the text or move the cursor</span>
  k:number, is-keycode?:boolean<span class="Special"> &lt;- </span>maybe-convert e:event, <span class="Constant">keycode:variant</span>
  assert is-keycode?, <span class="Constant">[event was of unknown type; neither keyboard nor mouse]</span>
  <span class="Comment"># handlers for each special key will go here</span>
<span class="Constant">  &lt;handle-special-key&gt;</span>
  go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
  <span class="muControl">return</span>
]

<span class="muRecipe">def</span> insert-at-cursor editor:address:editor-data, c:character, screen:address:screen<span class="muRecipe"> -&gt; </span>editor:address:editor-data, screen:address:screen, go-render?:boolean [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
  insert c, before-cursor
  before-cursor<span class="Special"> &lt;- </span>next before-cursor
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">before-cursor:offset</span>, before-cursor
  cursor-row:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-row:offset</span>
  cursor-column:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-column:offset</span>
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  save-row:number<span class="Special"> &lt;- </span>copy cursor-row
  save-column:number<span class="Special"> &lt;- </span>copy cursor-column
  screen-width:number<span class="Special"> &lt;- </span>screen-width screen
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  <span class="Comment"># occasionally we'll need to mess with the cursor</span>
<span class="Constant">  &lt;insert-character-special-case&gt;</span>
  <span class="Comment"># but mostly we'll just move the cursor right</span>
  cursor-column<span class="Special"> &lt;- </span>add cursor-column, <span class="Constant">1</span>
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, cursor-column
  next:address:duplex-list:character<span class="Special"> &lt;- </span>next before-cursor
  <span class="Delimiter">{</span>
    <span class="Comment"># at end of all text? no need to scroll? just print the character and leave</span>
    at-end?:boolean<span class="Special"> &lt;- </span>equal next, <span class="Constant">0/null</span>
    <span class="muControl">break-unless</span> at-end?
    bottom:number<span class="Special"> &lt;- </span>subtract screen-height, <span class="Constant">1</span>
    at-bottom?:boolean<span class="Special"> &lt;- </span>equal save-row, bottom
    at-right?:boolean<span class="Special"> &lt;- </span>equal save-column, right
    overflow?:boolean<span class="Special"> &lt;- </span>and at-bottom?, at-right?
    <span class="muControl">break-if</span> overflow?
    move-cursor screen, save-row, save-column
    print screen, c
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># not at right margin? print the character and rest of line</span>
    <span class="muControl">break-unless</span> next
    at-right?:boolean<span class="Special"> &lt;- </span>greater-or-equal cursor-column, screen-width
    <span class="muControl">break-if</span> at-right?
    curr:address:duplex-list:character<span class="Special"> &lt;- </span>copy before-cursor
    move-cursor screen, save-row, save-column
    curr-column:number<span class="Special"> &lt;- </span>copy save-column
    <span class="Delimiter">{</span>
      <span class="Comment"># hit right margin? give up and let caller render</span>
      go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
      at-right?:boolean<span class="Special"> &lt;- </span>greater-than curr-column, right
      <span class="muControl">return-if</span> at-right?
      <span class="muControl">break-unless</span> curr
      <span class="Comment"># newline? done.</span>
      currc:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
      at-newline?:boolean<span class="Special"> &lt;- </span>equal currc, <span class="Constant">10/newline</span>
      <span class="muControl">break-if</span> at-newline?
      print screen, currc
      curr-column<span class="Special"> &lt;- </span>add curr-column, <span class="Constant">1</span>
      curr<span class="Special"> &lt;- </span>next curr
      <span class="muControl">loop</span>
    <span class="Delimiter">}</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
  go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
  <span class="muControl">return</span>
]

<span class="Comment"># helper for tests</span>
<span class="muRecipe">def</span> editor-render screen:address:screen, editor:address:editor-data<span class="muRecipe"> -&gt; </span>screen:address:screen, editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  row:number, column:number<span class="Special"> &lt;- </span>render screen, editor
  clear-line-delimited screen, column, right
  row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
  draw-horizontal screen, row, left, right, <span class="Constant">9480/horizontal-dotted</span>
  row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
  clear-screen-from screen, row, left, left, right
]

<span class="muScenario">scenario</span> editor-handles-empty-event-queue [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
  assume-console <span class="Constant">[]</span>
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">1</span>  <span class="Comment"># on the 'b'</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor is at row 0..</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># ..and column 1</span>
  ]
  check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks-outside-text [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">7</span>  <span class="Comment"># last line, to the right of text</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor column</span>
  ]
  check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks-outside-text-2 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">def]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">7</span>  <span class="Comment"># interior line, to the right of text</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor column</span>
  ]
  check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks-outside-text-3 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">def]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">3</span>, <span class="Constant">7</span>  <span class="Comment"># below text</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor column</span>
  ]
  check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks-outside-column [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Comment"># editor occupies only left half of screen</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    <span class="Comment"># click on right half of screen</span>
    left-click <span class="Constant">3</span>, <span class="Constant">8</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
   <span class="Constant"> .          .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># no change to cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># ..or column</span>
  ]
  check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-handles-mouse-clicks-in-menu-area [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    <span class="Comment"># click on first, 'menu' row</span>
    left-click <span class="Constant">0</span>, <span class="Constant">3</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  <span class="Comment"># no change to cursor</span>
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> editor-inserts-characters-into-empty-editor [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    type <span class="Constant">[abc]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">3</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  <span class="Comment"># type two letters at different places</span>
  assume-console [
    type <span class="Constant">[0]</span>
    left-click <span class="Constant">1</span>, <span class="Constant">2</span>
    type <span class="Constant">[d]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .0adbc     .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">7</span>, <span class="Constant">[print-character]</span>  <span class="Comment"># 4 for first letter, 3 for second</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor-2 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">5</span>  <span class="Comment"># right of last line</span>
    type <span class="Constant">[d]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd      .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">1</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor-5 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">d]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">5</span>  <span class="Comment"># right of non-last line</span>
    type <span class="Constant">[e]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abce      .</span>
   <span class="Constant"> .d         .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">1</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor-3 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">3</span>, <span class="Constant">5</span>  <span class="Comment"># below all text</span>
    type <span class="Constant">[d]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd      .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">1</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor-4 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">d]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">3</span>, <span class="Constant">5</span>  <span class="Comment"># below all text</span>
    type <span class="Constant">[e]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
   <span class="Constant"> .de        .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">1</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-inserts-characters-at-cursor-6 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">d]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
<span class="Constant">  $clear-trace</span>
  assume-console [
    left-click <span class="Constant">3</span>, <span class="Constant">5</span>  <span class="Comment"># below all text</span>
    type <span class="Constant">[ef]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
   <span class="Constant"> .def       .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
  check-trace-count-for-label <span class="Constant">2</span>, <span class="Constant">[print-character]</span>
]

<span class="muScenario">scenario</span> editor-moves-cursor-after-inserting-characters [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
  assume-console [
    type <span class="Constant">[01]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .01ab      .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
   <span class="Constant"> .          .</span>
  ]
]

<span class="Comment"># if the cursor reaches the right margin, wrap the line</span>

<span class="muScenario">scenario</span> editor-wraps-line-on-insert [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
  <span class="Comment"># type a letter</span>
  assume-console [
    type <span class="Constant">[e]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  <span class="Comment"># no wrap yet</span>
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .eabc .</span>
<span class="Constant">    .┈┈┈┈┈.</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
  <span class="Comment"># type a second letter</span>
  assume-console [
    type <span class="Constant">[f]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  <span class="Comment"># now wrap</span>
  screen-should-contain [
   <span class="Constant"> .     .</span>
<span class="Constant">    .efab↩.</span>
   <span class="Constant"> .c    .</span>
<span class="Constant">    .┈┈┈┈┈.</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-wraps-line-on-insert-2 [
  <span class="Comment"># create an editor with some text</span>
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdefg</span>
<span class="Constant">defg]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  editor-render screen, <span class="Constant">2</span>:address:editor-data
  <span class="Comment"># type more text at the start</span>
  assume-console [
    left-click <span class="Constant">3</span>, <span class="Constant">0</span>
    type <span class="Constant">[abc]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  <span class="Comment"># cursor is not wrapped</span>
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">3</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">3</span>
  ]
  <span class="Comment"># but line is wrapped</span>
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd↩     .</span>
   <span class="Constant"> .efg       .</span>
   <span class="Constant"> .abcd↩     .</span>
   <span class="Constant"> .efg       .</span>
  ]
]

<span class="muRecipe">after</span> <span class="Constant">&lt;insert-character-special-case&gt;</span> [
  <span class="Comment"># if the line wraps at the cursor, move cursor to start of next row</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># if we're at the column just before the wrap indicator</span>
    wrap-column:number<span class="Special"> &lt;- </span>subtract right, <span class="Constant">1</span>
    at-wrap?:boolean<span class="Special"> &lt;- </span>greater-or-equal cursor-column, wrap-column
    <span class="muControl">break-unless</span> at-wrap?
    cursor-column<span class="Special"> &lt;- </span>subtract cursor-column, wrap-column
    cursor-column<span class="Special"> &lt;- </span>add cursor-column, left
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, cursor-column
    cursor-row<span class="Special"> &lt;- </span>add cursor-row, <span class="Constant">1</span>
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-row:offset</span>, cursor-row
    <span class="Comment"># if we're out of the screen, scroll down</span>
    <span class="Delimiter">{</span>
      below-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal cursor-row, screen-height
      <span class="muControl">break-unless</span> below-screen?
<span class="Constant">      &lt;scroll-down&gt;</span>
    <span class="Delimiter">}</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
]

<span class="muScenario">scenario</span> editor-wraps-cursor-after-inserting-characters [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">4</span>  <span class="Comment"># line is full; no wrap icon yet</span>
    type <span class="Constant">[f]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd↩     .</span>
   <span class="Constant"> .fe        .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
   <span class="Constant"> .          .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor column</span>
  ]
]

<span class="muScenario">scenario</span> editor-wraps-cursor-after-inserting-characters-2 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">3</span>  <span class="Comment"># right before the wrap icon</span>
    type <span class="Constant">[f]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcf↩     .</span>
   <span class="Constant"> .de        .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
   <span class="Constant"> .          .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
  ]
]

<span class="muScenario">scenario</span> editor-wraps-cursor-to-left-margin [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">2/left</span>, <span class="Constant">7/right</span>
  assume-console [
    left-click <span class="Constant">1</span>, <span class="Constant">5</span>  <span class="Comment"># line is full; no wrap icon yet</span>
    type <span class="Constant">[01]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .  abc0↩   .</span>
   <span class="Constant"> .  1de     .</span>
   <span class="Constant"> .  ┈┈┈┈┈   .</span>
   <span class="Constant"> .          .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor column</span>
  ]
]

<span class="Comment"># if newline, move cursor to start of next line, and maybe align indent with previous line</span>

<span class="muData">container</span> editor-data [
  indent?:boolean
]

<span class="muRecipe">after</span> <span class="Constant">&lt;editor-initialization&gt;</span> [
  *result<span class="Special"> &lt;- </span>put *result, <span class="Constant">indent?:offset</span>, <span class="Constant">1/true</span>
]

<span class="muScenario">scenario</span> editor-moves-cursor-down-after-inserting-newline [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  assume-console [
    type <span class="Constant">[0</span>
<span class="Constant">1]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .0         .</span>
   <span class="Constant"> .1abc      .</span>
<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
]

<span class="muRecipe">after</span> <span class="Constant">&lt;handle-special-character&gt;</span> [
  <span class="Delimiter">{</span>
    newline?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
    <span class="muControl">break-unless</span> newline?
<span class="Constant">    &lt;insert-enter-begin&gt;</span>
    editor<span class="Special"> &lt;- </span>insert-new-line-and-indent editor, screen
<span class="Constant">    &lt;insert-enter-end&gt;</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">def</span> insert-new-line-and-indent editor:address:editor-data, screen:address:screen<span class="muRecipe"> -&gt; </span>editor:address:editor-data, screen:address:screen, go-render?:boolean [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  cursor-row:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-row:offset</span>
  cursor-column:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-column:offset</span>
  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  <span class="Comment"># insert newline</span>
  insert <span class="Constant">10/newline</span>, before-cursor
  before-cursor<span class="Special"> &lt;- </span>next before-cursor
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">before-cursor:offset</span>, before-cursor
  cursor-row<span class="Special"> &lt;- </span>add cursor-row, <span class="Constant">1</span>
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-row:offset</span>, cursor-row
  cursor-column<span class="Special"> &lt;- </span>copy left
  *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-column:offset</span>, cursor-column
  <span class="Comment"># maybe scroll</span>
  <span class="Delimiter">{</span>
    below-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal cursor-row, screen-height  <span class="Comment"># must be equal, never greater</span>
    <span class="muControl">break-unless</span> below-screen?
<span class="Constant">    &lt;scroll-down&gt;</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
    cursor-row<span class="Special"> &lt;- </span>subtract cursor-row, <span class="Constant">1</span>  <span class="Comment"># bring back into screen range</span>
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">cursor-row:offset</span>, cursor-row
  <span class="Delimiter">}</span>
  <span class="Comment"># indent if necessary</span>
  indent?:boolean<span class="Special"> &lt;- </span>get *editor, <span class="Constant">indent?:offset</span>
  <span class="muControl">return-unless</span> indent?
  d:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
  end-of-previous-line:address:duplex-list:character<span class="Special"> &lt;- </span>prev before-cursor
  indent:number<span class="Special"> &lt;- </span>line-indent end-of-previous-line, d
  i:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  <span class="Delimiter">{</span>
    indent-done?:boolean<span class="Special"> &lt;- </span>greater-or-equal i, indent
    <span class="muControl">break-if</span> indent-done?
    editor, screen, go-render?:boolean<span class="Special"> &lt;- </span>insert-at-cursor editor, <span class="Constant">32/space</span>, screen
    i<span class="Special"> &lt;- </span>add i, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="Comment"># takes a pointer 'curr' into the doubly-linked list and its sentinel, counts</span>
<span class="Comment"># the number of spaces at the start of the line containing 'curr'.</span>
<span class="muRecipe">def</span> line-indent curr:address:duplex-list:character, start:address:duplex-list:character<span class="muRecipe"> -&gt; </span>result:number [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  result:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  <span class="muControl">return-unless</span> curr
  at-start?:boolean<span class="Special"> &lt;- </span>equal curr, start
  <span class="muControl">return-if</span> at-start?
  <span class="Delimiter">{</span>
    curr<span class="Special"> &lt;- </span>prev curr
    <span class="muControl">break-unless</span> curr
    at-start?:boolean<span class="Special"> &lt;- </span>equal curr, start
    <span class="muControl">break-if</span> at-start?
    c:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
    at-newline?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
    <span class="muControl">break-if</span> at-newline?
    <span class="Comment"># if c is a space, increment result</span>
    is-space?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">32/space</span>
    <span class="Delimiter">{</span>
      <span class="muControl">break-unless</span> is-space?
      result<span class="Special"> &lt;- </span>add result, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># if c is not a space, reset result</span>
    <span class="Delimiter">{</span>
      <span class="muControl">break-if</span> is-space?
      result<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
    <span class="Delimiter">}</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="muScenario">scenario</span> editor-moves-cursor-down-after-inserting-newline-2 [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">1/left</span>, <span class="Constant">10/right</span>
  assume-console [
    type <span class="Constant">[0</span>
<span class="Constant">1]</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> . 0        .</span>
   <span class="Constant"> . 1abc     .</span>
   <span class="Constant"> . ┈┈┈┈┈┈┈┈┈.</span>
   <span class="Constant"> .          .</span>
  ]
]

<span class="muScenario">scenario</span> editor-clears-previous-line-completely-after-inserting-newline [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  assume-console [
    press enter
  ]
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd↩     .</span>
   <span class="Constant"> .e         .</span>
   <span class="Constant"> .          .</span>
   <span class="Constant"> .          .</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
  ]
  <span class="Comment"># line should be fully cleared</span>
  screen-should-contain [
   <span class="Constant"> .          .</span>
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abcd↩     .</span>
   <span class="Constant"> .e         .</span>
   <span class="Constant"> .┈┈┈┈┈     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-inserts-indent-after-newline [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">10/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
<span class="Constant">  cd</span>
<span class="Constant">ef]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  <span class="Comment"># position cursor after 'cd' and hit 'newline'</span>
  assume-console [
    left-click <span class="Constant">2</span>, <span class="Constant">8</span>
    type [
]
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  <span class="Comment"># cursor should be below start of previous line</span>
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor column (indented)</span>
  ]
]

<span class="muScenario">scenario</span> editor-skips-indent-around-paste [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">10/height</span>
  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
<span class="Constant">  cd</span>
<span class="Constant">ef]</span>
  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  <span class="Comment"># position cursor after 'cd' and hit 'newline' surrounded by paste markers</span>
  assume-console [
    left-click <span class="Constant">2</span>, <span class="Constant">8</span>
    press <span class="Constant">65507</span>  <span class="Comment"># start paste</span>
    press enter
    press <span class="Constant">65506</span>  <span class="Comment"># end paste</span>
  ]
  run [
    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  <span class="Comment"># cursor should be below start of previous line</span>
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">3</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column (not indented)</span>
  ]
]

<span class="muRecipe">after</span> <span class="Constant">&lt;handle-special-key&gt;</span> [
  <span class="Delimiter">{</span>
    paste-start?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65507/paste-start</span>
    <span class="muControl">break-unless</span> paste-start?
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">indent?:offset</span>, <span class="Constant">0/false</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">after</span> <span class="Constant">&lt;handle-special-key&gt;</span> [
  <span class="Delimiter">{</span>
    paste-end?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65506/paste-end</span>
    <span class="muControl">break-unless</span> paste-end?
    *editor<span class="Special"> &lt;- </span>put *editor, <span class="Constant">indent?:offset</span>, <span class="Constant">1/true</span>
    go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
]

<span class="SalientComment">## helpers</span>

<span class="muRecipe">def</span> draw-horizontal screen:address:screen, row:number, x:number, right:number<span class="muRecipe"> -&gt; </span>screen:address:screen [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  style:character, style-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-if</span> style-found?
    style<span class="Special"> &lt;- </span>copy <span class="Constant">9472/horizontal</span>
  <span class="Delimiter">}</span>
  color:number, color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default color to white</span>
    <span class="muControl">break-if</span> color-found?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">245/grey</span>
  <span class="Delimiter">}</span>
  bg-color:number, bg-color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-if</span> bg-color-found?
    bg-color<span class="Special"> &lt;- </span>copy <span class="Constant">0/black</span>
  <span class="Delimiter">}</span>
  screen<span class="Special"> &lt;- </span>move-cursor screen, row, x
  <span class="Delimiter">{</span>
    continue?:boolean<span class="Special"> &lt;- </span>lesser-or-equal x, right  <span class="Comment"># right is inclusive, to match editor-data semantics</span>
    <span class="muControl">break-unless</span> continue?
    print screen, style, color, bg-color
    x<span class="Special"> &lt;- </span>add x, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->