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27d9de59 AC |
1 | (* HCoop Domtool (http://hcoop.sourceforge.net/) |
2 | * Copyright (c) 2006, Adam Chlipala | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version 2 | |
7 | * of the License, or (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | |
17 | *) | |
18 | ||
19 | (* Domtool configuration language type checking *) | |
20 | ||
21 | structure Tycheck :> TYCHECK = struct | |
22 | ||
23 | open Ast Print | |
24 | ||
25 | structure SM = StringMap | |
26 | ||
27 | type env = typ SM.map | |
28 | val empty = SM.empty | |
29 | ||
30 | local | |
31 | val unifCount = ref 0 | |
32 | in | |
33 | fun resetUnif () = unifCount := 0 | |
34 | ||
35 | fun newUnif () = | |
36 | let | |
37 | val c = !unifCount | |
38 | val name = | |
39 | if c < 26 then | |
40 | str (chr (ord #"A" + c)) | |
41 | else | |
42 | "UNIF" ^ Int.toString (c - 26) | |
43 | in | |
44 | unifCount := c + 1; | |
45 | TUnif (name, ref NONE) | |
46 | end | |
47 | end | |
48 | ||
49 | exception UnequalDomains | |
50 | ||
51 | fun eqRecord f (r1, r2) = | |
52 | (SM.appi (fn (k, v1) => | |
53 | case SM.find (r2, k) of | |
54 | NONE => raise UnequalDomains | |
55 | | SOME v2 => | |
56 | if f (v1, v2) then | |
57 | () | |
58 | else | |
59 | raise UnequalDomains) r1; | |
60 | SM.appi (fn (k, v2) => | |
61 | case SM.find (r1, k) of | |
62 | NONE => raise UnequalDomains | |
63 | | SOME v1 => | |
64 | if f (v1, v2) then | |
65 | () | |
66 | else | |
67 | raise UnequalDomains) r2; | |
68 | true) | |
69 | handle UnequalDomains => false | |
70 | ||
71 | fun eqPred ((p1, _), (p2, _)) = | |
72 | case (p1, p2) of | |
73 | (CRoot, CRoot) => true | |
74 | | (CConst s1, CConst s2) => s1 = s2 | |
75 | | (CPrefix p1, CPrefix p2) => eqPred (p1, p2) | |
76 | | (CNot p1, CNot p2) => eqPred (p1, p2) | |
77 | | (CAnd (p1, q1), CAnd (p2, q2)) => | |
78 | eqPred (p1, p2) andalso eqPred (q1, q2) | |
79 | ||
80 | | _ => false | |
81 | ||
82 | fun eqTy (t1All as (t1, _), t2All as (t2, _)) = | |
83 | case (t1, t2) of | |
84 | (TBase s1, TBase s2) => s1 = s2 | |
85 | | (TList t1, TList t2) => eqTy (t1, t2) | |
86 | | (TArrow (d1, r1), TArrow (d2, r2)) => | |
87 | eqTy (d1, d2) andalso eqTy (r1, r2) | |
88 | ||
89 | | (TAction (p1, d1, r1), TAction (p2, d2, r2)) => | |
90 | eqPred (p1, p2) andalso eqRecord eqTy (d1, d2) | |
91 | andalso eqRecord eqTy (r1, r2) | |
92 | ||
93 | | (TUnif (_, ref (SOME t1)), _) => eqTy (t1, t2All) | |
94 | | (_, TUnif (_, ref (SOME t2))) => eqTy (t1All, t2) | |
95 | ||
96 | | (TUnif (_, r1), TUnif (_, r2)) => r1 = r2 | |
97 | ||
98 | | (TError, TError) => true | |
99 | ||
100 | | _ => false | |
101 | ||
102 | datatype unification_error = | |
103 | UnifyPred of pred * pred | |
104 | | UnifyTyp of typ * typ | |
105 | | UnifyOccurs of string * typ | |
106 | ||
107 | exception Unify of unification_error | |
108 | ||
109 | datatype type_error = | |
110 | WrongType of string * exp * typ * typ * unification_error option | |
111 | | WrongForm of string * string * exp * typ * unification_error option | |
112 | | UnboundVariable of string | |
113 | ||
114 | fun preface (s, d) = printd (PD.hovBox (PD.PPS.Rel 0, | |
115 | [PD.string s, PD.space 1, d])) | |
116 | ||
117 | fun describe_unification_error t ue = | |
118 | case ue of | |
119 | UnifyPred (p1, p2) => | |
120 | (print "Reason: Incompatible predicates.\n"; | |
121 | preface ("Have:", p_pred p1); | |
122 | preface ("Need:", p_pred p2)) | |
123 | | UnifyTyp (t1, t2) => | |
124 | if eqTy (t, t1) then | |
125 | () | |
126 | else | |
127 | (print "Reason: Incompatible types.\n"; | |
128 | preface ("Have:", p_typ t1); | |
129 | preface ("Need:", p_typ t2)) | |
130 | | UnifyOccurs (name, t') => | |
131 | if eqTy (t, t') then | |
132 | () | |
133 | else | |
134 | (print "Reason: Occurs check failed for "; | |
135 | print name; | |
136 | print " in:\n"; | |
137 | printd (p_typ t)) | |
138 | ||
139 | fun describe_type_error loc te = | |
140 | case te of | |
141 | WrongType (place, e, t1, t2, ueo) => | |
142 | (ErrorMsg.error (SOME loc) (place ^ " has wrong type."); | |
143 | preface (" Expression:", p_exp e); | |
144 | preface ("Actual type:", p_typ t1); | |
145 | preface ("Needed type:", p_typ t2); | |
146 | Option.app (describe_unification_error t1) ueo) | |
147 | | WrongForm (place, form, e, t, ueo) => | |
148 | (ErrorMsg.error (SOME loc) (place ^ " has a non-" ^ form ^ " type."); | |
149 | preface ("Expression:", p_exp e); | |
150 | preface (" Type:", p_typ t); | |
151 | Option.app (describe_unification_error t) ueo) | |
152 | | UnboundVariable name => | |
153 | ErrorMsg.error (SOME loc) ("Unbound variable " ^ name ^ ".\n") | |
154 | ||
db427c67 | 155 | fun predImplies (p1All as (p1, _), p2All as (p2, _)) = |
27d9de59 | 156 | case (p1, p2) of |
db427c67 AC |
157 | (_, CPrefix (CRoot, _)) => true |
158 | | (CNot (CPrefix (CRoot, _), _), _) => true | |
159 | ||
160 | | (CRoot, CRoot) => true | |
161 | ||
162 | | (CConst s1, CConst s2) => s1 = s2 | |
163 | ||
164 | | (CPrefix p1, CPrefix p2) => predImplies (p1, p2) | |
165 | ||
166 | | (CNot p1, CNot p2) => predImplies (p2, p1) | |
27d9de59 | 167 | |
db427c67 AC |
168 | | (_, CAnd (p1, p2)) => predImplies (p1All, p1) andalso predImplies (p1All, p2) |
169 | | (CAnd (p1, p2), _) => predImplies (p1, p2All) orelse predImplies (p2, p2All) | |
170 | ||
171 | | _ => false | |
172 | ||
173 | fun predSimpl (pAll as (p, loc)) = | |
174 | case p of | |
175 | CRoot => pAll | |
176 | | CConst _ => pAll | |
177 | | CPrefix p => (CPrefix (predSimpl p), loc) | |
178 | | CNot p => (CNot (predSimpl p), loc) | |
179 | | CAnd (p1, p2) => | |
180 | let | |
181 | val p1' = predSimpl p1 | |
182 | val p2' = predSimpl p2 | |
183 | in | |
184 | case p1' of | |
185 | (CAnd (c1, c2), _) => predSimpl (CAnd (c1, (CAnd (c2, p2'), loc)), loc) | |
186 | | _ => if predImplies (p2', p1') then | |
187 | p2' | |
188 | else | |
189 | (CAnd (p1', p2'), loc) | |
190 | end | |
191 | ||
192 | fun unifyPred (p1, p2) = | |
193 | if predImplies (p1, p2) then | |
194 | () | |
195 | else | |
196 | raise (Unify (UnifyPred (p1, p2))) | |
27d9de59 AC |
197 | |
198 | fun unifyRecord f (r1, r2) = | |
199 | (SM.appi (fn (k, v1) => | |
200 | case SM.find (r2, k) of | |
201 | NONE => raise UnequalDomains | |
202 | | SOME v2 => f (v1, v2)) r1; | |
203 | SM.appi (fn (k, v2) => | |
204 | case SM.find (r1, k) of | |
205 | NONE => raise UnequalDomains | |
206 | | SOME v1 => f (v1, v2)) r2) | |
207 | ||
208 | fun occurs u (t, _) = | |
209 | case t of | |
210 | TBase _ => false | |
211 | | TList t => occurs u t | |
212 | | TArrow (d, r) => occurs u d orelse occurs u r | |
213 | | TAction (_, d, r) => | |
214 | List.exists (occurs u) (SM.listItems d) | |
215 | orelse List.exists (occurs u) (SM.listItems r) | |
216 | | TError => false | |
217 | | TUnif (_, ref (SOME t)) => occurs u t | |
218 | | TUnif (_, u') => u = u' | |
219 | ||
220 | fun unify (t1All as (t1, _), t2All as (t2, _)) = | |
221 | case (t1, t2) of | |
222 | (TBase s1, TBase s2) => | |
223 | if s1 = s2 then | |
224 | () | |
225 | else | |
226 | raise Unify (UnifyTyp (t1All, t2All)) | |
227 | | (TList t1, TList t2) => unify (t1, t2) | |
228 | | (TArrow (d1, r1), TArrow (d2, r2)) => | |
229 | (unify (d1, d2); | |
230 | unify (r1, r2)) | |
231 | ||
232 | | (TAction (p1, d1, r1), TAction (p2, d2, r2)) => | |
233 | ((unifyPred (p1, p2); | |
234 | unifyRecord unify (d1, d2); | |
235 | unifyRecord unify (r1, r2)) | |
236 | handle UnequalDomains => raise Unify (UnifyTyp (t1All, t2All))) | |
237 | ||
238 | | (TUnif (_, ref (SOME t1)), _) => unify (t1, t2All) | |
239 | | (_, TUnif (_, ref (SOME t2))) => unify (t1All, t2) | |
240 | ||
241 | | (TUnif (_, r1), TUnif (_, r2)) => | |
242 | if r1 = r2 then | |
243 | () | |
244 | else | |
245 | r1 := SOME t2All | |
246 | ||
247 | | (TUnif (name, r), _) => | |
248 | if occurs r t2All then | |
249 | raise (Unify (UnifyOccurs (name, t2All))) | |
250 | else | |
251 | r := SOME t2All | |
252 | ||
253 | | (_, TUnif (name, r)) => | |
254 | if occurs r t1All then | |
255 | raise (Unify (UnifyOccurs (name, t1All))) | |
256 | else | |
257 | r := SOME t1All | |
258 | ||
259 | | (TError, _) => () | |
260 | | (_, TError) => () | |
261 | ||
262 | | _ => raise Unify (UnifyTyp (t1All, t2All)) | |
263 | ||
264 | fun isError t = | |
265 | case t of | |
266 | (TError, _) => true | |
267 | | _ => false | |
268 | ||
db427c67 AC |
269 | fun whnorm (tAll as (t, loc)) = |
270 | case t of | |
271 | TUnif (_, ref (SOME tAll)) => whnorm tAll | |
272 | | _ => tAll | |
273 | ||
27d9de59 AC |
274 | fun checkExp G (eAll as (e, loc)) = |
275 | let | |
276 | val dte = describe_type_error loc | |
277 | in | |
278 | case e of | |
279 | EInt _ => (TBase "int", loc) | |
280 | | EString _ => (TBase "string", loc) | |
281 | | EList es => | |
282 | let | |
283 | val t = (newUnif (), loc) | |
284 | in | |
285 | foldl (fn (e', ret) => | |
286 | let | |
287 | val t' = checkExp G e' | |
288 | in | |
289 | (unify (t', t); | |
290 | if isError t' then | |
291 | (TList (TError, loc), loc) | |
292 | else | |
293 | ret) | |
294 | handle Unify ue => | |
295 | (dte (WrongType ("List element", | |
296 | e', | |
297 | t', | |
298 | t, | |
299 | SOME ue)); | |
300 | (TError, loc)) | |
301 | end) (TList t, loc) es | |
302 | end | |
303 | ||
304 | | ELam (x, to, e) => | |
305 | let | |
306 | val t = | |
307 | case to of | |
308 | NONE => (newUnif (), loc) | |
309 | | SOME t => t | |
310 | ||
311 | val G' = SM.insert (G, x, t) | |
312 | val t' = checkExp G' e | |
313 | in | |
314 | (TArrow (t, t'), loc) | |
315 | end | |
316 | | EVar x => | |
317 | (case SM.find (G, x) of | |
318 | NONE => (dte (UnboundVariable x); | |
319 | (TError, loc)) | |
320 | | SOME t => t) | |
321 | | EApp (func, arg) => | |
322 | let | |
323 | val dom = (newUnif (), loc) | |
324 | val ran = (newUnif (), loc) | |
325 | ||
326 | val tf = checkExp G func | |
327 | val ta = checkExp G arg | |
328 | in | |
329 | (unify (tf, (TArrow (dom, ran), loc)); | |
330 | unify (ta, dom) | |
331 | handle Unify ue => | |
332 | dte (WrongType ("Function argument", | |
333 | arg, | |
334 | ta, | |
335 | dom, | |
336 | SOME ue)); | |
337 | ran) | |
338 | handle Unify ue => | |
339 | (dte (WrongForm ("Function to be applied", | |
340 | "function", | |
341 | func, | |
342 | tf, | |
343 | SOME ue)); | |
344 | (TError, loc)) | |
345 | end | |
db427c67 AC |
346 | |
347 | | ESet (evar, e) => | |
348 | let | |
349 | val t = checkExp G e | |
350 | in | |
351 | (TAction ((CPrefix (CRoot, loc), loc), | |
352 | SM.empty, | |
353 | SM.insert (SM.empty, evar, t)), | |
354 | loc) | |
355 | end | |
356 | | EGet (x, evar, rest) => | |
357 | let | |
358 | val xt = (newUnif (), loc) | |
359 | val G' = SM.insert (G, x, xt) | |
360 | ||
361 | val rt = whnorm (checkExp G' rest) | |
362 | in | |
363 | case rt of | |
364 | (TAction (p, d, r), _) => | |
365 | (case SM.find (d, evar) of | |
366 | NONE => (TAction (p, SM.insert (d, evar, xt), r), loc) | |
367 | | SOME xt' => | |
368 | (unify (xt', xt) | |
369 | handle Unify ue => | |
370 | dte (WrongType ("Retrieved environment variable", | |
371 | (EVar x, loc), | |
372 | xt', | |
373 | xt, | |
374 | SOME ue)); | |
375 | rt)) | |
376 | | _ => (dte (WrongForm ("Body of environment variable read", | |
377 | "action", | |
378 | rest, | |
379 | rt, | |
380 | NONE)); | |
381 | (TError, loc)) | |
382 | end | |
383 | ||
384 | | ESeq [] => raise Fail "Empty ESeq" | |
385 | | ESeq [e1] => checkExp G e1 | |
386 | | ESeq (e1 :: rest) => | |
387 | let | |
388 | val e2 = (ESeq rest, loc) | |
389 | ||
390 | val t1 = whnorm (checkExp G e1) | |
391 | val t2 = whnorm (checkExp G e2) | |
392 | in | |
393 | case t1 of | |
394 | (TAction (p1, d1, r1), _) => | |
395 | (case t2 of | |
396 | (TAction (p2, d2, r2), _) => | |
397 | let | |
398 | val p' = predSimpl (CAnd (p1, p2), loc) | |
399 | ||
400 | val d' = SM.foldli (fn (name, t, d') => | |
401 | case SM.find (r1, name) of | |
402 | NONE => | |
403 | (case SM.find (d', name) of | |
404 | NONE => SM.insert (d', name, t) | |
405 | | SOME t' => | |
406 | (unify (t, t') | |
407 | handle Unify ue => | |
408 | dte (WrongType ("Shared environment variable", | |
409 | (EVar name, loc), | |
410 | t, | |
411 | t', | |
412 | SOME ue)); | |
413 | d')) | |
414 | | SOME t' => | |
415 | (unify (t, t') | |
416 | handle Unify ue => | |
417 | dte (WrongType ("Shared environment variable", | |
418 | (EVar name, loc), | |
419 | t, | |
420 | t', | |
421 | SOME ue)); | |
422 | d')) | |
423 | d1 d2 | |
424 | ||
425 | val r' = SM.foldli (fn (name, t, r') => SM.insert (r', name, t)) | |
426 | r1 r2 | |
427 | in | |
428 | (TAction (p', d', r'), loc) | |
429 | end | |
430 | | _ => (dte (WrongForm ("Action to be sequenced", | |
431 | "action", | |
432 | e2, | |
433 | t2, | |
434 | NONE)); | |
435 | (TError, loc))) | |
436 | | _ => (dte (WrongForm ("Action to be sequenced", | |
437 | "action", | |
438 | e1, | |
439 | t1, | |
440 | NONE)); | |
441 | (TError, loc)) | |
442 | end | |
443 | ||
444 | | ELocal e => | |
445 | let | |
446 | val rt = whnorm (checkExp G e) | |
447 | in | |
448 | case rt of | |
449 | (TAction (p, d, _), _) => | |
450 | (TAction (p, d, SM.empty), loc) | |
451 | | _ => (dte (WrongForm ("Body of local action", | |
452 | "action", | |
453 | e, | |
454 | rt, | |
455 | NONE)); | |
456 | (TError, loc)) | |
457 | end | |
27d9de59 AC |
458 | end |
459 | ||
460 | exception Ununif | |
461 | ||
462 | fun ununif (tAll as (t, loc)) = | |
463 | case t of | |
464 | TBase _ => tAll | |
465 | | TList t => (TList (ununif t), loc) | |
466 | | TArrow (d, r) => (TArrow (ununif d, ununif r), loc) | |
467 | | TAction (p, d, r) => (TAction (p, SM.map ununif d, SM.map ununif r), loc) | |
468 | | TUnif (_, ref (SOME t)) => ununif t | |
469 | | TError => tAll | |
470 | ||
471 | | TUnif (_, ref NONE) => raise Ununif | |
472 | ||
473 | fun hasError (t, _) = | |
474 | case t of | |
475 | TBase _ => false | |
476 | | TList t => hasError t | |
477 | | TArrow (d, r) => hasError d orelse hasError r | |
478 | | TAction (p, d, r) => List.exists hasError (SM.listItems d) | |
479 | orelse List.exists hasError (SM.listItems r) | |
480 | | TError => false | |
481 | | TUnif (_, ref (SOME t)) => hasError t | |
482 | | TUnif (_, ref NONE) => false | |
483 | ||
484 | ||
485 | fun checkUnit G (eAll as (_, loc)) = | |
486 | let | |
487 | val _ = resetUnif () | |
488 | val t = checkExp G eAll | |
489 | in | |
490 | if hasError t then | |
491 | t | |
492 | else | |
493 | ununif t | |
494 | handle Ununif => | |
495 | (ErrorMsg.error (SOME loc) "Unification variables remain in type:"; | |
496 | printd (p_typ t); | |
497 | t) | |
498 | end | |
499 | ||
500 | end |