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
|
;;; Guile Emac Lisp
;; Copyright (C) 2001 Free Software Foundation, Inc.
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Code:
(define-module (language elisp compile-tree-il)
#:use-module (language tree-il)
#:use-module (system base pmatch)
#:export (compile-tree-il))
; Find the source properties of some parsed expression if there are any
; associated with it.
(define (location x)
(and (pair? x)
(let ((props (source-properties x)))
(and (not (null? props))
props))))
; Values to use for Elisp's nil and t.
(define (nil-value loc) (make-const loc (@ (language elisp runtime) nil-value)))
(define (t-value loc) (make-const loc (@ (language elisp runtime) t-value)))
; Modules that contain the value and function slot bindings.
(define runtime '(language elisp runtime))
(define value-slot '(language elisp runtime value-slot))
(define function-slot '(language elisp runtime function-slot))
; Build a call to a primitive procedure nicely.
(define (call-primitive loc sym . args)
(make-application loc (make-primitive-ref loc sym) args))
; Error reporting routine for syntax/compilation problems or build code for
; a runtime-error output.
(define (report-error loc . args)
(apply error args))
(define (runtime-error loc msg . args)
(make-application loc (make-primitive-ref loc 'error)
(cons (make-const loc msg) args)))
; Generate code to ensure a fluid is there for further use of a given symbol.
; ensure-fluids-for does the same for a list of symbols and builds a sequence
; that executes the fluid-insurances first, followed by all body commands; this
; is a routine for convenience (needed with let, let*, lambda).
(define (ensure-fluid! loc sym module)
(let ((resolved-module (call-primitive loc 'resolve-module
(make-const loc module)))
(resolved-intf (call-primitive loc 'resolve-interface
(make-const loc module))))
(make-conditional loc
(call-primitive loc 'module-defined? resolved-intf (make-const loc sym))
(make-void loc)
(make-sequence loc
(list (call-primitive loc 'module-define!
resolved-module (make-const loc sym)
(call-primitive loc 'make-fluid))
(call-primitive loc 'module-export!
resolved-module
(call-primitive loc 'list (make-const loc sym)))
(call-primitive loc 'fluid-set!
(make-module-ref loc module sym #t)
(make-module-ref loc runtime 'void #t)))))))
(define (ensure-fluids-for loc syms module . body)
(make-sequence loc
`(,@(map (lambda (sym) (ensure-fluid! loc sym module)) syms)
,@body)))
; Generate code to reference a fluid saved variable.
(define (reference-variable loc sym module)
(make-sequence loc
(list (ensure-fluid! loc sym module)
(call-primitive loc 'fluid-ref
(make-module-ref loc module sym #t)))))
; Reference a variable and error if the value is void.
(define (reference-with-check loc sym module)
(let ((var (gensym)))
(make-let loc '(value) `(,var) `(,(reference-variable loc sym module))
(make-conditional loc
(call-primitive loc 'eq?
(make-module-ref loc runtime 'void #t)
(make-lexical-ref loc 'value var))
(runtime-error loc "variable is void:" (make-const loc sym))
(make-lexical-ref loc 'value var)))))
; Generate code to set a fluid saved variable.
(define (set-variable! loc sym module value)
(make-sequence loc
(list (ensure-fluid! loc sym module)
(call-primitive loc 'fluid-set!
(make-module-ref loc module sym #t)
value))))
; Process the bindings part of a let or let* expression; that is, check for
; correctness and bring it to the form ((sym1 . val1) (sym2 . val2) ...).
(define (process-let-bindings loc bindings)
(map (lambda (b)
(if (symbol? b)
(cons b 'nil)
(if (or (not (list? b))
(not (= (length b) 2)))
(report-error loc "expected symbol or list of 2 elements in let")
(if (not (symbol? (car b)))
(report-error loc "expected symbol in let")
(cons (car b) (cadr b))))))
bindings))
; Split the argument list of a lambda expression into required, optional and
; rest arguments and also check it is actually valid.
(define (split-lambda-arguments loc args)
(let iterate ((tail args)
(mode 'required)
(required '())
(optional '()))
(cond
((null? tail)
(values (reverse required) (reverse optional) #f))
((and (eq? mode 'required)
(eq? (car tail) '&optional))
(iterate (cdr tail) 'optional required optional))
((eq? (car tail) '&rest)
(if (or (null? (cdr tail))
(not (null? (cddr tail))))
(report-error loc "expected exactly one symbol after &rest")
(values (reverse required) (reverse optional) (cadr tail))))
(else
(if (not (symbol? (car tail)))
(report-error loc "expected symbol in argument list, got" (car tail))
(case mode
((required) (iterate (cdr tail) mode
(cons (car tail) required) optional))
((optional) (iterate (cdr tail) mode
required (cons (car tail) optional)))
((else) (error "invalid mode in split-lambda-arguments" mode))))))))
; Compile a lambda expression. Things get a little complicated because TreeIL
; does not allow optional arguments but only one rest argument, and also the
; rest argument should be nil instead of '() for no values given. Because of
; this, we have to do a little preprocessing to get everything done before the
; real body is called.
;
; (lambda (a &optional b &rest c) body) should become:
; (lambda (a_ . rest_)
; (with-fluids* (list a b c) (list a_ nil nil)
; (lambda ()
; (if (not (null? rest_))
; (begin
; (fluid-set! b (car rest_))
; (set! rest_ (cdr rest_))
; (if (not (null? rest_))
; (fluid-set! c rest_))))
; body)))
;
; This is formulated quite imperatively, but I think in this case that is quite
; clear and better than creating a lot of nested let's.
(define (compile-lambda loc args body)
(if (not (list? args))
(error "expected list for argument-list" args))
(if (null? body)
(error "function body might not be empty"))
(call-with-values
(lambda ()
(split-lambda-arguments loc args))
(lambda (required optional rest)
(let ((required-sym (map (lambda (sym) (gensym)) required))
(rest-sym (if (or rest (not (null? optional))) (gensym) '())))
(let ((real-args (append required-sym rest-sym))
(locals `(,@required ,@optional ,@(if rest (list rest) '()))))
(make-lambda loc
real-args real-args '()
(ensure-fluids-for loc locals value-slot
(call-primitive loc 'with-fluids*
(make-application loc (make-primitive-ref loc 'list)
(map (lambda (sym) (make-module-ref loc value-slot sym #t))
locals))
(make-application loc (make-primitive-ref loc 'list)
(append (map (lambda (sym) (make-lexical-ref loc sym sym))
required-sym)
(map (lambda (sym) (nil-value loc))
(if rest
`(,@optional ,rest-sym)
optional))))
(make-lambda loc '() '() '()
(make-sequence loc
`(,(process-optionals loc optional rest-sym)
,(process-rest loc rest rest-sym)
,@(map compile-expr body))))))))))))
; Build the code to handle setting of optional arguments that are present
; and updating the rest list.
(define (process-optionals loc optional rest-sym)
(let iterate ((tail optional))
(if (null? tail)
(make-void loc)
(make-conditional loc
(call-primitive loc 'null? (make-lexical-ref loc rest-sym rest-sym))
(make-void loc)
(make-sequence loc
(list (set-variable! loc (car tail) value-slot
(call-primitive loc 'car
(make-lexical-ref loc rest-sym rest-sym)))
(make-lexical-set loc rest-sym rest-sym
(call-primitive loc 'cdr
(make-lexical-ref loc rest-sym rest-sym)))
(iterate (cdr tail))))))))
; This builds the code to set the rest variable to nil if it is empty.
(define (process-rest loc rest rest-sym)
(let ((rest-empty (call-primitive loc 'null?
(make-lexical-ref loc rest-sym rest-sym))))
(cond
(rest
(make-conditional loc rest-empty
(make-void loc)
(set-variable! loc rest value-slot
(make-lexical-ref loc rest-sym rest-sym))))
((not (null? rest-sym))
(make-conditional loc rest-empty
(make-void loc)
(runtime-error loc "too many arguments and no rest argument")))
(else (make-void loc)))))
; Handle the common part of defconst and defvar, that is, checking for a correct
; doc string and arguments as well as maybe in the future handling the docstring
; somehow.
(define (handle-var-def loc sym doc)
(cond
((not (symbol? sym)) (report-error loc "expected symbol, got" sym))
((> (length doc) 1) (report-error loc "too many arguments to defvar"))
((and (not (null? doc)) (not (string? (car doc))))
(report-error loc "expected string as third argument of defvar, got"
(car doc)))
; TODO: Handle doc string if present.
(else #t)))
; Compile a symbol expression. This is a variable reference or maybe some
; special value like nil.
(define (compile-symbol loc sym)
(case sym
((nil) (nil-value loc))
((t) (t-value loc))
(else (reference-with-check loc sym value-slot))))
; Compile a pair-expression (that is, any structure-like construct).
(define (compile-pair loc expr)
(pmatch expr
((progn . ,forms)
(make-sequence loc (map compile-expr forms)))
((if ,condition ,ifclause)
(make-conditional loc (compile-expr condition)
(compile-expr ifclause)
(nil-value loc)))
((if ,condition ,ifclause ,elseclause)
(make-conditional loc (compile-expr condition)
(compile-expr ifclause)
(compile-expr elseclause)))
((if ,condition ,ifclause . ,elses)
(make-conditional loc (compile-expr condition)
(compile-expr ifclause)
(make-sequence loc (map compile-expr elses))))
; For (cond ...) forms, a special case is a (condition) clause without
; body. In this case, the value of condition itself should be returned,
; and thus is saved in a local variable for testing and returning, if it
; is found true.
((cond . ,clauses) (guard (and-map (lambda (el)
(and (list? el) (not (null? el))))
clauses))
(let iterate ((tail clauses))
(if (null? tail)
(nil-value loc)
(let ((cur (car tail)))
(if (null? (cdr cur))
(let ((var (gensym)))
(make-let loc
'(condition) `(,var) `(,(compile-expr (car cur)))
(make-conditional loc
(make-lexical-ref loc 'condition var)
(make-lexical-ref loc 'condition var)
(iterate (cdr tail)))))
(make-conditional loc
(compile-expr (car cur))
(make-sequence loc (map compile-expr (cdr cur)))
(iterate (cdr tail))))))))
((and) (t-value loc))
((and . ,expressions)
(let iterate ((tail expressions))
(if (null? (cdr tail))
(compile-expr (car tail))
(make-conditional loc
(compile-expr (car tail))
(iterate (cdr tail))
(nil-value loc)))))
((or . ,expressions)
(let iterate ((tail expressions))
(if (null? tail)
(nil-value loc)
(let ((var (gensym)))
(make-let loc
'(condition) `(,var) `(,(compile-expr (car tail)))
(make-conditional loc
(make-lexical-ref loc 'condition var)
(make-lexical-ref loc 'condition var)
(iterate (cdr tail))))))))
((defconst ,sym ,value . ,doc)
(if (handle-var-def loc sym doc)
(make-sequence loc
(list (set-variable! loc sym value-slot (compile-expr value))
(make-const loc sym)))))
((defvar ,sym) (make-const loc sym))
((defvar ,sym ,value . ,doc)
(if (handle-var-def loc sym doc)
(make-sequence loc
(list (make-conditional loc
(call-primitive loc 'eq?
(make-module-ref loc runtime 'void #t)
(reference-variable loc sym value-slot))
(set-variable! loc sym value-slot (compile-expr value))
(make-void loc))
(make-const loc sym)))))
; Build a set form for possibly multiple values. The code is not formulated
; tail recursive because it is clearer this way and large lists of symbol
; expression pairs are very unlikely.
((setq . ,args)
(make-sequence loc
(let iterate ((tail args))
(if (null? tail)
(list (make-void loc))
(let ((sym (car tail))
(tailtail (cdr tail)))
(if (not (symbol? sym))
(report-error loc "expected symbol in setq")
(if (null? tailtail)
(report-error loc "missing value for symbol in setq" sym)
(let* ((val (compile-expr (car tailtail)))
(op (set-variable! loc sym value-slot val)))
(cons op (iterate (cdr tailtail)))))))))))
; Let is done with a single call to with-fluids* binding them locally to new
; values.
((let ,bindings . ,body) (guard (and (list? bindings)
(list? body)
(not (null? bindings))
(not (null? body))))
(let ((bind (process-let-bindings loc bindings)))
(ensure-fluids-for loc (map car bind) value-slot
(call-primitive loc 'with-fluids*
(make-application loc (make-primitive-ref loc 'list)
(map (lambda (el)
(make-module-ref loc value-slot (car el) #t))
bind))
(make-application loc (make-primitive-ref loc 'list)
(map (lambda (el)
(compile-expr (cdr el)))
bind))
(make-lambda loc '() '() '()
(make-sequence loc (map compile-expr body)))))))
; Let* is compiled to a cascaded set of with-fluid* for each binding in turn
; so that each one already sees the preceding bindings.
((let* ,bindings . ,body) (guard (and (list? bindings)
(list? body)
(not (null? bindings))
(not (null? body))))
(let ((bind (process-let-bindings loc bindings)))
(ensure-fluids-for loc (map car bind) value-slot
(let iterate ((tail bind))
(if (null? tail)
(make-sequence loc (map compile-expr body))
(call-primitive loc 'with-fluid*
(make-module-ref loc value-slot (caar tail) #t)
(compile-expr (cdar tail))
(make-lambda loc '() '() '() (iterate (cdr tail)))))))))
; A while construct is transformed into a tail-recursive loop like this:
; (letrec ((iterate (lambda ()
; (if condition
; (begin body
; (iterate))
; %nil))))
; (iterate))
((while ,condition . ,body)
(let* ((itersym (gensym))
(compiled-body (map compile-expr body))
(iter-call (make-application loc
(make-lexical-ref loc 'iterate itersym)
(list)))
(full-body (make-sequence loc
`(,@compiled-body ,iter-call)))
(lambda-body (make-conditional loc
(compile-expr condition)
full-body
(nil-value loc)))
(iter-thunk (make-lambda loc '() '() '() lambda-body)))
(make-letrec loc '(iterate) (list itersym) (list iter-thunk)
iter-call)))
; Either (lambda ...) or (function (lambda ...)) denotes a lambda-expression
; that should be compiled.
((lambda ,args . ,body)
(compile-lambda loc args body))
((function (lambda ,args . ,body))
(compile-lambda loc args body))
; Build a lambda and also assign it to the function cell of some symbol.
((defun ,name ,args . ,body)
(if (not (symbol? name))
(error "expected symbol as function name" name)
(make-sequence loc
(list (set-variable! loc name function-slot
(compile-lambda loc args body))
(make-const loc name)))))
(('quote ,val)
(make-const loc val))
; Function calls using (function args) standard notation; here, we have to
; take the function value of a symbol if it is one. It seems that functions
; in form of uncompiled lists are not supported in this syntax, so we don't
; have to care for them.
((,func . ,args)
(make-application loc
(if (symbol? func)
(reference-with-check loc func function-slot)
(compile-expr func))
(map compile-expr args)))
(else
(report-error loc "unrecognized elisp" expr))))
; Compile a single expression to TreeIL.
(define (compile-expr expr)
(let ((loc (location expr)))
(cond
((symbol? expr)
(compile-symbol loc expr))
((pair? expr)
(compile-pair loc expr))
(else (make-const loc expr)))))
; Entry point for compilation to TreeIL.
(define (compile-tree-il expr env opts)
(values
(compile-expr expr)
env
env))
|