| 1 | ;;; Guile Emac Lisp |
| 2 | |
| 3 | ;; Copyright (C) 2001 Free Software Foundation, Inc. |
| 4 | |
| 5 | ;; This program is free software; you can redistribute it and/or modify |
| 6 | ;; it under the terms of the GNU General Public License as published by |
| 7 | ;; the Free Software Foundation; either version 2, or (at your option) |
| 8 | ;; any later version. |
| 9 | ;; |
| 10 | ;; This program is distributed in the hope that it will be useful, |
| 11 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | ;; GNU General Public License for more details. |
| 14 | ;; |
| 15 | ;; You should have received a copy of the GNU General Public License |
| 16 | ;; along with this program; see the file COPYING. If not, write to |
| 17 | ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 18 | ;; Boston, MA 02111-1307, USA. |
| 19 | |
| 20 | ;;; Code: |
| 21 | |
| 22 | (define-module (language elisp compile-tree-il) |
| 23 | #:use-module (language tree-il) |
| 24 | #:use-module (system base pmatch) |
| 25 | #:export (compile-tree-il)) |
| 26 | |
| 27 | |
| 28 | ; Find the source properties of some parsed expression if there are any |
| 29 | ; associated with it. |
| 30 | |
| 31 | (define (location x) |
| 32 | (and (pair? x) |
| 33 | (let ((props (source-properties x))) |
| 34 | (and (not (null? props)) |
| 35 | props)))) |
| 36 | |
| 37 | |
| 38 | ; Value to use for Elisp's nil and t. |
| 39 | |
| 40 | (define (nil-value loc) (make-const loc #f)) |
| 41 | (define (t-value loc) (make-const loc #t)) |
| 42 | |
| 43 | |
| 44 | ; Modules that contain the value and function slot bindings. |
| 45 | |
| 46 | (define runtime '(language elisp runtime)) |
| 47 | (define value-slot '(language elisp runtime value-slot)) |
| 48 | (define function-slot '(language elisp runtime function-slot)) |
| 49 | |
| 50 | |
| 51 | ; Build a call to a primitive procedure nicely. |
| 52 | |
| 53 | (define (call-primitive loc sym . args) |
| 54 | (make-application loc (make-primitive-ref loc sym) args)) |
| 55 | |
| 56 | |
| 57 | ; Error reporting routine for syntax/compilation problems or build code for |
| 58 | ; a runtime-error output. |
| 59 | |
| 60 | (define (report-error loc . args) |
| 61 | (apply error args)) |
| 62 | |
| 63 | (define (runtime-error loc msg . args) |
| 64 | (make-application loc (make-primitive-ref loc 'error) |
| 65 | (cons (make-const loc msg) args))) |
| 66 | |
| 67 | |
| 68 | ; Generate code to ensure a fluid is there for further use of a given symbol. |
| 69 | |
| 70 | (define (ensure-fluid! loc sym module) |
| 71 | ; FIXME: Do this! |
| 72 | (make-void loc)) |
| 73 | |
| 74 | |
| 75 | ; Generate code to reference a fluid saved variable. |
| 76 | |
| 77 | (define (reference-variable loc sym module) |
| 78 | (make-sequence loc |
| 79 | (list (ensure-fluid! loc sym module) |
| 80 | (call-primitive loc 'fluid-ref |
| 81 | (make-module-ref loc module sym #t))))) |
| 82 | |
| 83 | |
| 84 | ; Reference a variable and error if the value is void. |
| 85 | |
| 86 | (define (reference-with-check loc sym module) |
| 87 | (let ((var (gensym))) |
| 88 | (make-let loc '(value) `(,var) `(,(reference-variable loc sym module)) |
| 89 | (make-conditional loc |
| 90 | (call-primitive loc 'eq? |
| 91 | (make-module-ref loc runtime 'void #t) |
| 92 | (make-lexical-ref loc 'value var)) |
| 93 | (runtime-error loc "variable is void:" (make-const loc sym)) |
| 94 | (make-lexical-ref loc 'value var))))) |
| 95 | |
| 96 | |
| 97 | ; Generate code to set a fluid saved variable. |
| 98 | |
| 99 | (define (set-variable! loc sym module value) |
| 100 | (make-sequence loc |
| 101 | (list (ensure-fluid! loc sym module) |
| 102 | (call-primitive loc 'fluid-set! |
| 103 | (make-module-ref loc module sym #t) |
| 104 | value)))) |
| 105 | |
| 106 | |
| 107 | ; Process the bindings part of a let or let* expression; that is, check for |
| 108 | ; correctness and bring it to the form ((sym1 . val1) (sym2 . val2) ...). |
| 109 | |
| 110 | (define (process-let-bindings loc bindings) |
| 111 | (map (lambda (b) |
| 112 | (if (symbol? b) |
| 113 | (cons b 'nil) |
| 114 | (if (or (not (list? b)) |
| 115 | (not (= (length b) 2))) |
| 116 | (report-error loc "expected symbol or list of 2 elements in let") |
| 117 | (if (not (symbol? (car b))) |
| 118 | (report-error loc "expected symbol in let") |
| 119 | (cons (car b) (cadr b)))))) |
| 120 | bindings)) |
| 121 | |
| 122 | |
| 123 | ; Split the argument list of a lambda expression into required, optional and |
| 124 | ; rest arguments and also check it is actually valid. |
| 125 | |
| 126 | (define (split-lambda-arguments loc args) |
| 127 | (let iterate ((tail args) |
| 128 | (mode 'required) |
| 129 | (required '()) |
| 130 | (optional '())) |
| 131 | (cond |
| 132 | |
| 133 | ((null? tail) |
| 134 | (values (reverse required) (reverse optional) #f)) |
| 135 | |
| 136 | ((and (eq? mode 'required) |
| 137 | (eq? (car tail) '&optional)) |
| 138 | (iterate (cdr tail) 'optional required optional)) |
| 139 | |
| 140 | ((eq? (car tail) '&rest) |
| 141 | (if (or (null? (cdr tail)) |
| 142 | (not (null? (cddr tail)))) |
| 143 | (report-error loc "expected exactly one symbol after &rest") |
| 144 | (values (reverse required) (reverse optional) (cadr tail)))) |
| 145 | |
| 146 | (else |
| 147 | (if (not (symbol? (car tail))) |
| 148 | (report-error loc "expected symbol in argument list, got" (car tail)) |
| 149 | (case mode |
| 150 | ((required) (iterate (cdr tail) mode |
| 151 | (cons (car tail) required) optional)) |
| 152 | ((optional) (iterate (cdr tail) mode |
| 153 | required (cons (car tail) optional))) |
| 154 | ((else) (error "invalid mode in split-lambda-arguments" mode)))))))) |
| 155 | |
| 156 | |
| 157 | ; Compile a lambda expression. Things get a little complicated because TreeIL |
| 158 | ; does not allow optional arguments but only one rest argument, and also the |
| 159 | ; rest argument should be nil instead of '() for no values given. Because of |
| 160 | ; this, we have to do a little preprocessing to get everything done before the |
| 161 | ; real body is called. |
| 162 | ; |
| 163 | ; (lambda (a &optional b &rest c) body) should become: |
| 164 | ; (lambda (a_ . rest_) |
| 165 | ; (with-fluids* (list a b c) (list a_ nil nil) |
| 166 | ; (lambda () |
| 167 | ; (if (not (null? rest_)) |
| 168 | ; (begin |
| 169 | ; (fluid-set! b (car rest_)) |
| 170 | ; (set! rest_ (cdr rest_)) |
| 171 | ; (if (not (null? rest_)) |
| 172 | ; (fluid-set! c rest_)))) |
| 173 | ; body))) |
| 174 | ; |
| 175 | ; This is formulated quite imperatively, but I think in this case that is quite |
| 176 | ; clear and better than creating a lot of nested let's. |
| 177 | |
| 178 | (define (compile-lambda loc args body) |
| 179 | (call-with-values |
| 180 | (lambda () |
| 181 | (split-lambda-arguments loc args)) |
| 182 | (lambda (required optional rest) |
| 183 | ; FIXME: Ensure fluids there! |
| 184 | (let ((required-sym (map (lambda (sym) (gensym)) required)) |
| 185 | (rest-sym (if (or rest (not (null? optional))) (gensym) '()))) |
| 186 | (let ((real-args (append required-sym rest-sym))) |
| 187 | (make-lambda loc |
| 188 | real-args real-args '() |
| 189 | (call-primitive loc 'with-fluids* |
| 190 | (make-application loc (make-primitive-ref loc 'list) |
| 191 | (map (lambda (sym) (make-module-ref loc value-slot sym #t)) |
| 192 | (append (append required optional) |
| 193 | (if rest (list rest) '())))) |
| 194 | (make-application loc (make-primitive-ref loc 'list) |
| 195 | (append (map (lambda (sym) (make-lexical-ref loc sym sym)) |
| 196 | required-sym) |
| 197 | (map (lambda (sym) (nil-value loc)) |
| 198 | (if (null? rest-sym) |
| 199 | optional |
| 200 | (append optional (list rest-sym)))))) |
| 201 | (make-lambda loc '() '() '() |
| 202 | (make-sequence loc |
| 203 | (cons (process-optionals loc optional rest-sym) |
| 204 | (cons (process-rest loc rest rest-sym) |
| 205 | (map compile-expr body)))))))))))) |
| 206 | |
| 207 | ; Build the code to handle setting of optional arguments that are present |
| 208 | ; and updating the rest list. |
| 209 | (define (process-optionals loc optional rest-sym) |
| 210 | (let iterate ((tail optional)) |
| 211 | (if (null? tail) |
| 212 | (make-void loc) |
| 213 | (make-conditional loc |
| 214 | (call-primitive loc 'null? (make-lexical-ref loc rest-sym rest-sym)) |
| 215 | (make-void loc) |
| 216 | (make-sequence loc |
| 217 | (list (set-variable! loc (car tail) value-slot |
| 218 | (call-primitive loc 'car |
| 219 | (make-lexical-ref loc rest-sym rest-sym))) |
| 220 | (make-lexical-set loc rest-sym rest-sym |
| 221 | (call-primitive loc 'cdr |
| 222 | (make-lexical-ref loc rest-sym rest-sym))) |
| 223 | (iterate (cdr tail)))))))) |
| 224 | |
| 225 | ; This builds the code to set the rest variable to nil if it is empty. |
| 226 | (define (process-rest loc rest rest-sym) |
| 227 | (let ((rest-empty (call-primitive loc 'null? |
| 228 | (make-lexical-ref loc rest-sym rest-sym)))) |
| 229 | (cond |
| 230 | (rest |
| 231 | (make-conditional loc rest-empty |
| 232 | (make-void loc) |
| 233 | (set-variable! loc rest value-slot |
| 234 | (make-lexical-ref loc rest-sym rest-sym)))) |
| 235 | ((not (null? rest-sym)) |
| 236 | (make-conditional loc rest-empty |
| 237 | (make-void loc) |
| 238 | (runtime-error loc "too many arguments and no rest argument"))) |
| 239 | (else (make-void loc))))) |
| 240 | |
| 241 | |
| 242 | ; Compile a symbol expression. This is a variable reference or maybe some |
| 243 | ; special value like nil. |
| 244 | |
| 245 | (define (compile-symbol loc sym) |
| 246 | (case sym |
| 247 | |
| 248 | ((nil) (nil-value loc)) |
| 249 | |
| 250 | ((t) (t-value loc)) |
| 251 | |
| 252 | (else |
| 253 | (reference-with-check loc sym value-slot)))) |
| 254 | |
| 255 | |
| 256 | ; Compile a pair-expression (that is, any structure-like construct). |
| 257 | |
| 258 | (define (compile-pair loc expr) |
| 259 | (pmatch expr |
| 260 | |
| 261 | ((progn . ,forms) |
| 262 | (make-sequence loc (map compile-expr forms))) |
| 263 | |
| 264 | ((if ,condition ,ifclause) |
| 265 | (make-conditional loc (compile-expr condition) |
| 266 | (compile-expr ifclause) |
| 267 | (nil-value loc))) |
| 268 | ((if ,condition ,ifclause ,elseclause) |
| 269 | (make-conditional loc (compile-expr condition) |
| 270 | (compile-expr ifclause) |
| 271 | (compile-expr elseclause))) |
| 272 | ((if ,condition ,ifclause . ,elses) |
| 273 | (make-conditional loc (compile-expr condition) |
| 274 | (compile-expr ifclause) |
| 275 | (make-sequence loc (map compile-expr elses)))) |
| 276 | |
| 277 | ; For (cond ...) forms, a special case is a (condition) clause without |
| 278 | ; body. In this case, the value of condition itself should be returned, |
| 279 | ; and thus is saved in a local variable for testing and returning, if it |
| 280 | ; is found true. |
| 281 | ((cond . ,clauses) (guard (and-map (lambda (el) |
| 282 | (and (list? el) (not (null? el)))) |
| 283 | clauses)) |
| 284 | (let iterate ((tail clauses)) |
| 285 | (if (null? tail) |
| 286 | (nil-value loc) |
| 287 | (let ((cur (car tail))) |
| 288 | (if (null? (cdr cur)) |
| 289 | (let ((var (gensym))) |
| 290 | (make-let loc |
| 291 | '(condition) `(,var) `(,(compile-expr (car cur))) |
| 292 | (make-conditional loc |
| 293 | (make-lexical-ref loc 'condition var) |
| 294 | (make-lexical-ref loc 'condition var) |
| 295 | (iterate (cdr tail))))) |
| 296 | (make-conditional loc |
| 297 | (compile-expr (car cur)) |
| 298 | (make-sequence loc (map compile-expr (cdr cur))) |
| 299 | (iterate (cdr tail)))))))) |
| 300 | |
| 301 | ((and) (t-value loc)) |
| 302 | ((and . ,expressions) |
| 303 | (let iterate ((tail expressions)) |
| 304 | (if (null? (cdr tail)) |
| 305 | (compile-expr (car tail)) |
| 306 | (make-conditional loc |
| 307 | (compile-expr (car tail)) |
| 308 | (iterate (cdr tail)) |
| 309 | (nil-value loc))))) |
| 310 | |
| 311 | ((or . ,expressions) |
| 312 | (let iterate ((tail expressions)) |
| 313 | (if (null? tail) |
| 314 | (nil-value loc) |
| 315 | (let ((var (gensym))) |
| 316 | (make-let loc |
| 317 | '(condition) `(,var) `(,(compile-expr (car tail))) |
| 318 | (make-conditional loc |
| 319 | (make-lexical-ref loc 'condition var) |
| 320 | (make-lexical-ref loc 'condition var) |
| 321 | (iterate (cdr tail)))))))) |
| 322 | |
| 323 | ; Build a set form for possibly multiple values. The code is not formulated |
| 324 | ; tail recursive because it is clearer this way and large lists of symbol |
| 325 | ; expression pairs are very unlikely. |
| 326 | ((setq . ,args) |
| 327 | (make-sequence loc |
| 328 | (let iterate ((tail args)) |
| 329 | (if (null? tail) |
| 330 | (list (make-void loc)) |
| 331 | (let ((sym (car tail)) |
| 332 | (tailtail (cdr tail))) |
| 333 | (if (not (symbol? sym)) |
| 334 | (report-error loc "expected symbol in setq") |
| 335 | (if (null? tailtail) |
| 336 | (report-error loc "missing value for symbol in setq" sym) |
| 337 | (let* ((val (compile-expr (car tailtail))) |
| 338 | (op (set-variable! loc sym value-slot val))) |
| 339 | (cons op (iterate (cdr tailtail))))))))))) |
| 340 | |
| 341 | ; Let is done with a single call to with-fluids* binding them locally to new |
| 342 | ; values. |
| 343 | ((let ,bindings . ,body) (guard (and (list? bindings) |
| 344 | (list? body) |
| 345 | (not (null? bindings)) |
| 346 | (not (null? body)))) |
| 347 | (let ((bind (process-let-bindings loc bindings))) |
| 348 | (call-primitive loc 'with-fluids* |
| 349 | (make-application loc (make-primitive-ref loc 'list) |
| 350 | (map (lambda (el) |
| 351 | (make-module-ref loc value-slot (car el) #t)) |
| 352 | bind)) |
| 353 | (make-application loc (make-primitive-ref loc 'list) |
| 354 | (map (lambda (el) |
| 355 | (compile-expr (cdr el))) |
| 356 | bind)) |
| 357 | (make-lambda loc '() '() '() |
| 358 | (make-sequence loc (map compile-expr body)))))) |
| 359 | |
| 360 | ; Let* is compiled to a cascaded set of with-fluid* for each binding in turn |
| 361 | ; so that each one already sees the preceding bindings. |
| 362 | ((let* ,bindings . ,body) (guard (and (list? bindings) |
| 363 | (list? body) |
| 364 | (not (null? bindings)) |
| 365 | (not (null? body)))) |
| 366 | (let ((bind (process-let-bindings loc bindings))) |
| 367 | (let iterate ((tail bind)) |
| 368 | (if (null? tail) |
| 369 | (make-sequence loc (map compile-expr body)) |
| 370 | (call-primitive loc 'with-fluid* |
| 371 | (make-module-ref loc value-slot (caar tail) #t) |
| 372 | (compile-expr (cdar tail)) |
| 373 | (make-lambda loc '() '() '() (iterate (cdr tail)))))))) |
| 374 | |
| 375 | ; A while construct is transformed into a tail-recursive loop like this: |
| 376 | ; (letrec ((iterate (lambda () |
| 377 | ; (if condition |
| 378 | ; (begin body |
| 379 | ; (iterate)) |
| 380 | ; %nil)))) |
| 381 | ; (iterate)) |
| 382 | ((while ,condition . ,body) |
| 383 | (let* ((itersym (gensym)) |
| 384 | (compiled-body (map compile-expr body)) |
| 385 | (iter-call (make-application loc |
| 386 | (make-lexical-ref loc 'iterate itersym) |
| 387 | (list))) |
| 388 | (full-body (make-sequence loc |
| 389 | (append compiled-body (list iter-call)))) |
| 390 | (lambda-body (make-conditional loc |
| 391 | (compile-expr condition) |
| 392 | full-body |
| 393 | (nil-value loc))) |
| 394 | (iter-thunk (make-lambda loc '() '() '() lambda-body))) |
| 395 | (make-letrec loc '(iterate) (list itersym) (list iter-thunk) |
| 396 | iter-call))) |
| 397 | |
| 398 | ; Either (lambda ...) or (function (lambda ...)) denotes a lambda-expression |
| 399 | ; that should be compiled. |
| 400 | ((lambda ,args . ,body) (guard (not (null? body))) |
| 401 | (compile-lambda loc args body)) |
| 402 | ((function (lambda ,args . ,body)) (guard (not (null? body))) |
| 403 | (compile-lambda loc args body)) |
| 404 | |
| 405 | (('quote ,val) |
| 406 | (make-const loc val)) |
| 407 | |
| 408 | (else |
| 409 | (report-error loc "unrecognized elisp" expr)))) |
| 410 | |
| 411 | |
| 412 | ; Compile a single expression to TreeIL. |
| 413 | |
| 414 | (define (compile-expr expr) |
| 415 | (let ((loc (location expr))) |
| 416 | (cond |
| 417 | ((symbol? expr) |
| 418 | (compile-symbol loc expr)) |
| 419 | ((pair? expr) |
| 420 | (compile-pair loc expr)) |
| 421 | (else (make-const loc expr))))) |
| 422 | |
| 423 | |
| 424 | ; Entry point for compilation to TreeIL. |
| 425 | |
| 426 | (define (compile-tree-il expr env opts) |
| 427 | (values |
| 428 | (compile-expr expr) |
| 429 | env |
| 430 | env)) |