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
|
<!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 - 075channel.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; }
.muScenario { color: #00af00; }
.muData { color: #ffff00; }
.SalientComment { color: #00ffff; }
.Delimiter { color: #800080; }
.muRecipe { color: #ff8700; }
.Comment { color: #9090ff; }
.Constant { color: #00a0a0; }
.Special { color: #c00000; }
.muControl { color: #c0a020; }
-->
</style>
<script type='text/javascript'>
<!--
-->
</script>
</head>
<body>
<pre id='vimCodeElement'>
<span class="Comment"># Mu synchronizes using channels rather than locks, like Erlang and Go.</span>
<span class="Comment">#</span>
<span class="Comment"># The two ends of a channel will usually belong to different routines, but</span>
<span class="Comment"># each end should (currently) only be used by a single one. Don't try to read</span>
<span class="Comment"># from or write to it from multiple routines at once.</span>
<span class="Comment">#</span>
<span class="Comment"># Key properties of channels:</span>
<span class="Comment">#</span>
<span class="Comment"># a) Writing to a full channel or reading from an empty one will put the</span>
<span class="Comment"># current routine in 'waiting' state until the operation can be completed.</span>
<span class="Comment">#</span>
<span class="Comment"># b) Writing to a channel implicitly performs a deep copy, to prevent</span>
<span class="Comment"># addresses from being shared between routines, thereby causing race</span>
<span class="Comment"># conditions.</span>
<span class="muScenario">scenario</span> channel [
run [
<span class="Constant">local-scope</span>
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
<span class="Constant">10</span>:number/<span class="Special">raw</span>, <span class="Constant">11</span>:boolean/<span class="Special">raw</span>, source<span class="Special"> <- </span>read source
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">34</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># read was successful</span>
]
]
<span class="muData">container</span> channel:_elem [
<span class="Comment"># To avoid locking, writer and reader will never write to the same location.</span>
<span class="Comment"># So channels will include fields in pairs, one for the writer and one for the</span>
<span class="Comment"># reader.</span>
first-full:number <span class="Comment"># for write</span>
first-free:number <span class="Comment"># for read</span>
<span class="Comment"># A circular buffer contains values from index first-full up to (but not</span>
<span class="Comment"># including) index first-empty. The reader always modifies it at first-full,</span>
<span class="Comment"># while the writer always modifies it at first-empty.</span>
data:address:array:_elem
]
<span class="Comment"># Since channels have two ends, and since it's an error to use either end from</span>
<span class="Comment"># multiple routines, let's distinguish the ends.</span>
<span class="muData">container</span> source:_elem [
chan:address:channel:_elem
]
<span class="muData">container</span> sink:_elem [
chan:address:channel:_elem
]
<span class="muRecipe">def</span> new-channel capacity:number<span class="muRecipe"> -> </span>in:address:source:_elem, out:address:sink:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
result:address:channel:_elem<span class="Special"> <- </span>new <span class="Delimiter">{</span>(channel _elem): type<span class="Delimiter">}</span>
*result<span class="Special"> <- </span>put *result, <span class="Constant">first-full:offset</span>, <span class="Constant">0</span>
*result<span class="Special"> <- </span>put *result, <span class="Constant">first-free:offset</span>, <span class="Constant">0</span>
capacity<span class="Special"> <- </span>add capacity, <span class="Constant">1</span> <span class="Comment"># unused slot for 'full?' below</span>
data:address:array:_elem<span class="Special"> <- </span>new <span class="Constant">_elem:type</span>, capacity
*result<span class="Special"> <- </span>put *result, <span class="Constant">data:offset</span>, data
in<span class="Special"> <- </span>new <span class="Delimiter">{</span>(source _elem): type<span class="Delimiter">}</span>
*in<span class="Special"> <- </span>put *in, <span class="Constant">chan:offset</span>, result
out<span class="Special"> <- </span>new <span class="Delimiter">{</span>(sink _elem): type<span class="Delimiter">}</span>
*out<span class="Special"> <- </span>put *out, <span class="Constant">chan:offset</span>, result
]
<span class="muRecipe">def</span> write out:address:sink:_elem, val:_elem<span class="muRecipe"> -> </span>out:address:sink:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
assert out, <span class="Constant">[write to null channel]</span>
chan:address:channel:_elem<span class="Special"> <- </span>get *out, <span class="Constant">chan:offset</span>
<span class="Constant"> <channel-write-initial></span>
<span class="Delimiter">{</span>
<span class="Comment"># block if chan is full</span>
full:boolean<span class="Special"> <- </span>channel-full? chan
<span class="muControl">break-unless</span> full
full-address:location<span class="Special"> <- </span>get-location *chan, <span class="Constant">first-full:offset</span>
wait-for-location full-address
<span class="Delimiter">}</span>
<span class="Comment"># store a deep copy of val</span>
circular-buffer:address:array:_elem<span class="Special"> <- </span>get *chan, <span class="Constant">data:offset</span>
free:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-free:offset</span>
val-copy:_elem<span class="Special"> <- </span>deep-copy val <span class="Comment"># on this instruction rests all Mu's concurrency-safety</span>
*circular-buffer<span class="Special"> <- </span>put-index *circular-buffer, free, val-copy
<span class="Comment"># mark its slot as filled</span>
free<span class="Special"> <- </span>add free, <span class="Constant">1</span>
<span class="Delimiter">{</span>
<span class="Comment"># wrap free around to 0 if necessary</span>
len:number<span class="Special"> <- </span>length *circular-buffer
at-end?:boolean<span class="Special"> <- </span>greater-or-equal free, len
<span class="muControl">break-unless</span> at-end?
free<span class="Special"> <- </span>copy <span class="Constant">0</span>
<span class="Delimiter">}</span>
<span class="Comment"># write back</span>
*chan<span class="Special"> <- </span>put *chan, <span class="Constant">first-free:offset</span>, free
]
<span class="muRecipe">def</span> read in:address:source:_elem<span class="muRecipe"> -> </span>result:_elem, eof?:boolean, in:address:source:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
assert in, <span class="Constant">[read on null channel]</span>
eof?<span class="Special"> <- </span>copy <span class="Constant">0/false</span> <span class="Comment"># default result</span>
chan:address:channel:_elem<span class="Special"> <- </span>get *in, <span class="Constant">chan:offset</span>
<span class="Delimiter">{</span>
<span class="Comment"># block if chan is empty</span>
empty?:boolean<span class="Special"> <- </span>channel-empty? chan
<span class="muControl">break-unless</span> empty?
<span class="Constant"> <channel-read-empty></span>
free-address:location<span class="Special"> <- </span>get-location *chan, <span class="Constant">first-free:offset</span>
wait-for-location free-address
<span class="Delimiter">}</span>
<span class="Comment"># pull result off</span>
full:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-full:offset</span>
circular-buffer:address:array:_elem<span class="Special"> <- </span>get *chan, <span class="Constant">data:offset</span>
result<span class="Special"> <- </span>index *circular-buffer, full
<span class="Comment"># clear the slot</span>
empty:address:_elem<span class="Special"> <- </span>new <span class="Constant">_elem:type</span>
*circular-buffer<span class="Special"> <- </span>put-index *circular-buffer, full, *empty
<span class="Comment"># mark its slot as empty</span>
full<span class="Special"> <- </span>add full, <span class="Constant">1</span>
<span class="Delimiter">{</span>
<span class="Comment"># wrap full around to 0 if necessary</span>
len:number<span class="Special"> <- </span>length *circular-buffer
at-end?:boolean<span class="Special"> <- </span>greater-or-equal full, len
<span class="muControl">break-unless</span> at-end?
full<span class="Special"> <- </span>copy <span class="Constant">0</span>
<span class="Delimiter">}</span>
<span class="Comment"># write back</span>
*chan<span class="Special"> <- </span>put *chan, <span class="Constant">first-full:offset</span>, full
]
<span class="muRecipe">def</span> clear in:address:source:_elem<span class="muRecipe"> -> </span>in:address:source:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
chan:address:channel:_elem<span class="Special"> <- </span>get *in, <span class="Constant">chan:offset</span>
<span class="Delimiter">{</span>
empty?:boolean<span class="Special"> <- </span>channel-empty? chan
<span class="muControl">break-if</span> empty?
_, _, in<span class="Special"> <- </span>read in
<span class="Delimiter">}</span>
]
<span class="muScenario">scenario</span> channel-initialization [
run [
<span class="Constant">local-scope</span>
source:address:source:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
<span class="Constant">10</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-full:offset</span>
<span class="Constant">11</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># first-full</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># first-free</span>
]
]
<span class="muScenario">scenario</span> channel-write-increments-free [
run [
<span class="Constant">local-scope</span>
_, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
chan:address:channel:number<span class="Special"> <- </span>get *sink, <span class="Constant">chan:offset</span>
<span class="Constant">10</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-full:offset</span>
<span class="Constant">11</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># first-full</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># first-free</span>
]
]
<span class="muScenario">scenario</span> channel-read-increments-full [
run [
<span class="Constant">local-scope</span>
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
_, _, source<span class="Special"> <- </span>read source
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
<span class="Constant">10</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-full:offset</span>
<span class="Constant">11</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># first-full</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># first-free</span>
]
]
<span class="muScenario">scenario</span> channel-wrap [
run [
<span class="Constant">local-scope</span>
<span class="Comment"># channel with just 1 slot</span>
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">1/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
<span class="Comment"># write and read a value</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
_, _, source<span class="Special"> <- </span>read source
<span class="Comment"># first-free will now be 1</span>
<span class="Constant">10</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
<span class="Constant">11</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
<span class="Comment"># write second value, verify that first-free wraps</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
<span class="Constant">20</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-free:offset</span>
<span class="Comment"># read second value, verify that first-full wraps</span>
_, _, source<span class="Special"> <- </span>read source
<span class="Constant">30</span>:number/<span class="Special">raw <- </span>get *chan, <span class="Constant">first-full:offset</span>
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># first-free after first write</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># first-full after first read</span>
<span class="Constant">20</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># first-free after second write, wrapped</span>
<span class="Constant">30</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># first-full after second read, wrapped</span>
]
]
<span class="muScenario">scenario</span> channel-new-empty-not-full [
run [
<span class="Constant">local-scope</span>
source:address:source:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
<span class="Constant">10</span>:boolean/<span class="Special">raw <- </span>channel-empty? chan
<span class="Constant">11</span>:boolean/<span class="Special">raw <- </span>channel-full? chan
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># empty?</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># full?</span>
]
]
<span class="muScenario">scenario</span> channel-write-not-empty [
run [
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">3/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
<span class="Constant">10</span>:boolean/<span class="Special">raw <- </span>channel-empty? chan
<span class="Constant">11</span>:boolean/<span class="Special">raw <- </span>channel-full? chan
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># empty?</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># full?</span>
]
]
<span class="muScenario">scenario</span> channel-write-full [
run [
<span class="Constant">local-scope</span>
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">1/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
<span class="Constant">10</span>:boolean/<span class="Special">raw <- </span>channel-empty? chan
<span class="Constant">11</span>:boolean/<span class="Special">raw <- </span>channel-full? chan
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># empty?</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># full?</span>
]
]
<span class="muScenario">scenario</span> channel-read-not-full [
run [
<span class="Constant">local-scope</span>
source:address:source:number, sink:address:sink:number<span class="Special"> <- </span>new-channel <span class="Constant">1/capacity</span>
chan:address:channel:number<span class="Special"> <- </span>get *source, <span class="Constant">chan:offset</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">34</span>
_, _, source<span class="Special"> <- </span>read source
<span class="Constant">10</span>:boolean/<span class="Special">raw <- </span>channel-empty? chan
<span class="Constant">11</span>:boolean/<span class="Special">raw <- </span>channel-full? chan
]
memory-should-contain [
<span class="Constant">10</span><span class="Special"> <- </span><span class="Constant">1</span> <span class="Comment"># empty?</span>
<span class="Constant">11</span><span class="Special"> <- </span><span class="Constant">0</span> <span class="Comment"># full?</span>
]
]
<span class="SalientComment">## cancelling channels</span>
<span class="Comment"># every channel comes with a boolean signifying if it's been closed</span>
<span class="Comment"># initially this boolean is false</span>
<span class="muData">container</span> channel:_elem [
closed?:boolean
]
<span class="Comment"># a channel can be closed from either the source or the sink</span>
<span class="Comment"># both routines can modify the 'closed?' bit, but they can only ever set it, so this is a benign race</span>
<span class="muRecipe">def</span> close x:address:source:_elem<span class="muRecipe"> -> </span>x:address:source:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
chan:address:channel:_elem<span class="Special"> <- </span>get *x, <span class="Constant">chan:offset</span>
*chan<span class="Special"> <- </span>put *chan, <span class="Constant">closed?:offset</span>, <span class="Constant">1/true</span>
]
<span class="muRecipe">def</span> close x:address:sink:_elem<span class="muRecipe"> -> </span>x:address:sink:_elem [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
chan:address:channel:_elem<span class="Special"> <- </span>get *x, <span class="Constant">chan:offset</span>
*chan<span class="Special"> <- </span>put *chan, <span class="Constant">closed?:offset</span>, <span class="Constant">1/true</span>
]
<span class="Comment"># once a channel is closed from one side, no further operations are expected from that side</span>
<span class="Comment"># if a channel is closed for reading,</span>
<span class="Comment"># no further writes will be let through</span>
<span class="Comment"># if a channel is closed for writing,</span>
<span class="Comment"># future reads continue until the channel empties,</span>
<span class="Comment"># then the channel is also closed for reading</span>
<span class="muRecipe">after</span> <span class="Constant"><channel-write-initial></span> [
closed?:boolean<span class="Special"> <- </span>get *chan, <span class="Constant">closed?:offset</span>
<span class="muControl">return-if</span> closed?
]
<span class="muRecipe">after</span> <span class="Constant"><channel-read-empty></span> [
closed?:boolean<span class="Special"> <- </span>get *chan, <span class="Constant">closed?:offset</span>
<span class="Delimiter">{</span>
<span class="muControl">break-unless</span> closed?
empty-result:address:_elem<span class="Special"> <- </span>new <span class="Constant">_elem:type</span>
<span class="muControl">return</span> *empty-result, <span class="Constant">1/true</span>
<span class="Delimiter">}</span>
]
<span class="SalientComment">## helpers</span>
<span class="Comment"># An empty channel has first-empty and first-full both at the same value.</span>
<span class="muRecipe">def</span> channel-empty? chan:address:channel:_elem<span class="muRecipe"> -> </span>result:boolean [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
<span class="Comment"># return chan.first-full == chan.first-free</span>
full:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-full:offset</span>
free:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-free:offset</span>
result<span class="Special"> <- </span>equal full, free
]
<span class="Comment"># A full channel has first-empty just before first-full, wasting one slot.</span>
<span class="Comment"># (Other alternatives: <a href="https://en.wikipedia.org/wiki/Circular_buffer#Full_.2F_Empty_Buffer_Distinction)">https://en.wikipedia.org/wiki/Circular_buffer#Full_.2F_Empty_Buffer_Distinction)</a></span>
<span class="muRecipe">def</span> channel-full? chan:address:channel:_elem<span class="muRecipe"> -> </span>result:boolean [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
<span class="Comment"># tmp = chan.first-free + 1</span>
tmp:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-free:offset</span>
tmp<span class="Special"> <- </span>add tmp, <span class="Constant">1</span>
<span class="Delimiter">{</span>
<span class="Comment"># if tmp == chan.capacity, tmp = 0</span>
len:number<span class="Special"> <- </span>capacity chan
at-end?:boolean<span class="Special"> <- </span>greater-or-equal tmp, len
<span class="muControl">break-unless</span> at-end?
tmp<span class="Special"> <- </span>copy <span class="Constant">0</span>
<span class="Delimiter">}</span>
<span class="Comment"># return chan.first-full == tmp</span>
full:number<span class="Special"> <- </span>get *chan, <span class="Constant">first-full:offset</span>
result<span class="Special"> <- </span>equal full, tmp
]
<span class="muRecipe">def</span> capacity chan:address:channel:_elem<span class="muRecipe"> -> </span>result:number [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
q:address:array:_elem<span class="Special"> <- </span>get *chan, <span class="Constant">data:offset</span>
result<span class="Special"> <- </span>length *q
]
<span class="Comment"># helper for channels of characters in particular</span>
<span class="muRecipe">def</span> buffer-lines in:address:source:character, buffered-out:address:sink:character<span class="muRecipe"> -> </span>buffered-out:address:sink:character, in:address:source:character [
<span class="Constant">local-scope</span>
<span class="Constant">load-ingredients</span>
<span class="Comment"># repeat forever</span>
eof?:boolean<span class="Special"> <- </span>copy <span class="Constant">0/false</span>
<span class="Delimiter">{</span>
line:address:buffer<span class="Special"> <- </span>new-buffer <span class="Constant">30</span>
<span class="Comment"># read characters from 'in' until newline, copy into line</span>
<span class="Delimiter">{</span>
<span class="Constant"> +next-character</span>
c:character, eof?:boolean, in<span class="Special"> <- </span>read in
<span class="muControl">break-if</span> eof?
<span class="Comment"># drop a character on backspace</span>
<span class="Delimiter">{</span>
<span class="Comment"># special-case: if it's a backspace</span>
backspace?:boolean<span class="Special"> <- </span>equal c, <span class="Constant">8</span>
<span class="muControl">break-unless</span> backspace?
<span class="Comment"># drop previous character</span>
<span class="Delimiter">{</span>
buffer-length:number<span class="Special"> <- </span>get *line, <span class="Constant">length:offset</span>
buffer-empty?:boolean<span class="Special"> <- </span>equal buffer-length, <span class="Constant">0</span>
<span class="muControl">break-if</span> buffer-empty?
buffer-length<span class="Special"> <- </span>subtract buffer-length, <span class="Constant">1</span>
*line<span class="Special"> <- </span>put *line, <span class="Constant">length:offset</span>, buffer-length
<span class="Delimiter">}</span>
<span class="Comment"># and don't append this one</span>
<span class="muControl">loop</span> <span class="Constant">+next-character:label</span>
<span class="Delimiter">}</span>
<span class="Comment"># append anything else</span>
line<span class="Special"> <- </span>append line, c
line-done?:boolean<span class="Special"> <- </span>equal c, <span class="Constant">10/newline</span>
<span class="muControl">break-if</span> line-done?
<span class="muControl">loop</span>
<span class="Delimiter">}</span>
<span class="Comment"># copy line into 'buffered-out'</span>
i:number<span class="Special"> <- </span>copy <span class="Constant">0</span>
line-contents:address:array:character<span class="Special"> <- </span>get *line, <span class="Constant">data:offset</span>
max:number<span class="Special"> <- </span>get *line, <span class="Constant">length:offset</span>
<span class="Delimiter">{</span>
done?:boolean<span class="Special"> <- </span>greater-or-equal i, max
<span class="muControl">break-if</span> done?
c:character<span class="Special"> <- </span>index *line-contents, i
buffered-out<span class="Special"> <- </span>write buffered-out, c
i<span class="Special"> <- </span>add i, <span class="Constant">1</span>
<span class="muControl">loop</span>
<span class="Delimiter">}</span>
<span class="Delimiter">{</span>
<span class="muControl">break-unless</span> eof?
buffered-out<span class="Special"> <- </span>close buffered-out
<span class="muControl">return</span>
<span class="Delimiter">}</span>
<span class="muControl">loop</span>
<span class="Delimiter">}</span>
]
<span class="muScenario">scenario</span> buffer-lines-blocks-until-newline [
run [
<span class="Constant">local-scope</span>
source:address:source:character, sink:address:sink:character<span class="Special"> <- </span>new-channel <span class="Constant">10/capacity</span>
_, buffered-stdin:address:sink:character/buffered-stdin<span class="Special"> <- </span>new-channel <span class="Constant">10/capacity</span>
buffered-chan:address:channel:character<span class="Special"> <- </span>get *buffered-stdin, <span class="Constant">chan:offset</span>
empty?:boolean<span class="Special"> <- </span>channel-empty? buffered-chan
assert empty?, <span class="Constant">[ </span>
<span class="Constant">F buffer-lines-blocks-until-newline: channel should be empty after init]</span>
<span class="Comment"># buffer stdin into buffered-stdin, try to read from buffered-stdin</span>
buffer-routine:number<span class="Special"> <- </span>start-running buffer-lines, source, buffered-stdin
wait-for-routine-to-block buffer-routine
empty?<span class="Special"> <- </span>channel-empty? buffered-chan
assert empty?:boolean, <span class="Constant">[ </span>
<span class="Constant">F buffer-lines-blocks-until-newline: channel should be empty after buffer-lines bring-up]</span>
<span class="Comment"># write 'a'</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">97/a</span>
restart buffer-routine
wait-for-routine-to-block buffer-routine
empty?<span class="Special"> <- </span>channel-empty? buffered-chan
assert empty?:boolean, <span class="Constant">[ </span>
<span class="Constant">F buffer-lines-blocks-until-newline: channel should be empty after writing 'a']</span>
<span class="Comment"># write 'b'</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">98/b</span>
restart buffer-routine
wait-for-routine-to-block buffer-routine
empty?<span class="Special"> <- </span>channel-empty? buffered-chan
assert empty?:boolean, <span class="Constant">[ </span>
<span class="Constant">F buffer-lines-blocks-until-newline: channel should be empty after writing 'b']</span>
<span class="Comment"># write newline</span>
sink<span class="Special"> <- </span>write sink, <span class="Constant">10/newline</span>
restart buffer-routine
wait-for-routine-to-block buffer-routine
empty?<span class="Special"> <- </span>channel-empty? buffered-chan
data-emitted?:boolean<span class="Special"> <- </span>not empty?
assert data-emitted?, <span class="Constant">[ </span>
<span class="Constant">F buffer-lines-blocks-until-newline: channel should contain data after writing newline]</span>
trace <span class="Constant">1</span>, <span class="Constant">[test]</span>, <span class="Constant">[reached end]</span>
]
trace-should-contain [
test: reached end
]
]
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->
|