[gforth] / gforth / objects.fs  

gforth: gforth/objects.fs


1 : anton 1.1 \ yet another Forth objects extension
2 :    
3 : anton 1.11 \ written by Anton Ertl 1996-1998
4 : anton 1.4 \ public domain; NO WARRANTY
5 : anton 1.1
6 : anton 1.2 \ This (in combination with compat/struct.fs) is in ANS Forth (with an
7 :     \ environmental dependence on case insensitivity; convert everything
8 :     \ to upper case for state sensitive systems).
9 : anton 1.1
10 : anton 1.2 \ compat/struct.fs and this file together use the following words:
11 :    
12 :     \ from CORE :
13 : anton 1.4 \ : 1- + swap invert and ; DOES> @ immediate drop Create rot dup , >r
14 :     \ r> IF ELSE THEN over chars aligned cells 2* here - allot execute
15 :     \ POSTPONE ?dup 2dup move Variable 2@ 2! ! ['] >body = 2drop ' r@ +!
16 :     \ Constant recurse 1+ BEGIN 0= UNTIL negate Literal ." .
17 : anton 1.2 \ from CORE-EXT :
18 : anton 1.4 \ tuck pick nip true <> 0> erase Value :noname compile,
19 : anton 1.2 \ from BLOCK-EXT :
20 :     \ \
21 :     \ from DOUBLE :
22 : anton 1.3 \ 2Constant
23 : anton 1.2 \ from EXCEPTION :
24 :     \ throw catch
25 :     \ from EXCEPTION-EXT :
26 :     \ abort"
27 :     \ from FILE :
28 :     \ (
29 :     \ from FLOAT :
30 : anton 1.4 \ faligned floats
31 : anton 1.2 \ from FLOAT-EXT :
32 : anton 1.4 \ dfaligned dfloats sfaligned sfloats
33 : anton 1.3 \ from LOCAL :
34 :     \ TO
35 : anton 1.2 \ from MEMORY :
36 : anton 1.3 \ allocate resize free
37 :     \ from SEARCH :
38 :     \ get-order set-order wordlist get-current set-current
39 : anton 1.2
40 : anton 1.1 \ needs struct.fs
41 :    
42 :     \ helper words
43 :    
44 : anton 1.6 s" gforth" environment? [if]
45 :     2drop
46 :     [else]
47 :    
48 : anton 1.1 : -rot ( a b c -- c a b )
49 :     rot rot ;
50 :    
51 :     : perform ( ... addr -- ... )
52 :     @ execute ;
53 :    
54 : anton 1.3 : ?dup-if ( compilation: -- orig ; run-time: n -- n| )
55 :     POSTPONE ?dup POSTPONE if ; immediate
56 :    
57 : anton 1.1 : save-mem ( addr1 u -- addr2 u ) \ gforth
58 :     \ copy a memory block into a newly allocated region in the heap
59 :     swap >r
60 :     dup allocate throw
61 :     swap 2dup r> -rot move ;
62 :    
63 : anton 1.3 : resize ( a-addr1 u -- a-addr2 ior ) \ gforth
64 :     over
65 :     if
66 :     resize
67 :     else
68 :     nip allocate
69 :     then ;
70 :    
71 : anton 1.1 : extend-mem ( addr1 u1 u -- addr addr2 u2 )
72 :     \ extend memory block allocated from the heap by u aus
73 : anton 1.4 \ the (possibly reallocated) piece is addr2 u2, the extension is at addr
74 : anton 1.1 over >r + dup >r resize throw
75 :     r> over r> + -rot ;
76 :    
77 : anton 1.6 : \g ( -- )
78 :     postpone \ ; immediate
79 :     [then]
80 :    
81 : anton 1.3 \ data structures
82 : anton 1.1
83 :     struct
84 : anton 1.4 cell% field object-map
85 :     end-struct object%
86 : anton 1.1
87 :     struct
88 : anton 1.4 cell% 2* field interface-map
89 :     cell% field interface-map-offset \ aus
90 : anton 1.3 \ difference between where interface-map points and where
91 :     \ object-map points (0 for non-classes)
92 : anton 1.4 cell% field interface-offset \ aus
93 : anton 1.3 \ offset of interface map-pointer in class-map (0 for classes)
94 : anton 1.4 end-struct interface%
95 : anton 1.3
96 : anton 1.4 interface%
97 :     cell% field class-parent
98 : anton 1.5 cell% field class-wordlist \ inst-vars and other protected words
99 : anton 1.10 cell% 2* field class-inst-size ( class -- addr ) \ objects- objects
100 : crook 1.12 \g Give the size specification for an instance (i.e. an object)
101 :     \g of @var{class};
102 :     \g used as @code{class-inst-size 2@ ( class -- align size )}.
103 : anton 1.4 end-struct class%
104 : anton 1.1
105 : anton 1.3 struct
106 : anton 1.4 cell% field selector-offset \ the offset within the (interface) map
107 :     cell% field selector-interface \ the interface offset
108 :     end-struct selector%
109 : anton 1.3
110 :     \ maps are not defined explicitly; they have the following structure:
111 :    
112 :     \ pointers to interface maps (for classes) <- interface-map points here
113 : anton 1.4 \ interface%/class% pointer <- (object-)map points here
114 : anton 1.3 \ xts of methods
115 :    
116 : anton 1.1
117 : anton 1.3 \ code
118 : anton 1.1
119 : anton 1.3 \ selectors and methods
120 :    
121 : anton 1.10 variable current-interface ( -- addr ) \ objects- objects
122 : crook 1.12 \g Variable: contains the class or interface currently being
123 : anton 1.6 \g defined.
124 :    
125 :    
126 : anton 1.1
127 :     : no-method ( -- )
128 : anton 1.3 true abort" no method defined for this object/selector combination" ;
129 :    
130 :     : do-class-method ( -- )
131 :     does> ( ... object -- ... )
132 : anton 1.5 ( object selector-body )
133 : anton 1.3 selector-offset @ over object-map @ + ( object xtp ) perform ;
134 :    
135 :     : do-interface-method ( -- )
136 :     does> ( ... object -- ... )
137 :     ( object selector-body )
138 :     2dup selector-interface @ ( object selector-body object interface-offset )
139 :     swap object-map @ + @ ( object selector-body map )
140 :     swap selector-offset @ + perform ;
141 : anton 1.1
142 : anton 1.10 : method ( xt "name" -- ) \ objects- objects
143 : anton 1.6 \g @code{name} execution: @code{... object -- ...}@*
144 : crook 1.12 \g Create selector @var{name} and makes @var{xt} its method in
145 : anton 1.6 \g the current class.
146 : anton 1.3 create
147 :     current-interface @ interface-map 2@ ( xt map-addr map-size )
148 :     dup current-interface @ interface-map-offset @ - ,
149 :     1 cells extend-mem current-interface @ interface-map 2! ! ( )
150 :     current-interface @ interface-offset @ dup ,
151 :     ( 0<> ) if
152 :     do-interface-method
153 :     else
154 :     do-class-method
155 :     then ;
156 : anton 1.1
157 : anton 1.10 : selector ( "name" -- ) \ objects- objects
158 : crook 1.12 \g @var{name} execution: @code{... object -- ...}@*
159 :     \g Create selector @var{name} for the current class and its
160 : anton 1.6 \g descendents; you can set a method for the selector in the
161 :     \g current class with @code{overrides}.
162 : anton 1.1 ['] no-method method ;
163 :    
164 : anton 1.3 : interface-override! ( xt sel-xt interface-map -- )
165 :     \ xt is the new method for the selector sel-xt in interface-map
166 :     swap >body ( xt map selector-body )
167 :     selector-offset @ + ! ;
168 :    
169 : anton 1.10 : class->map ( class -- map ) \ objects- objects
170 : crook 1.12 \g @var{map} is the pointer to @var{class}'s method map; it
171 : anton 1.6 \g points to the place in the map to which the selector offsets
172 : crook 1.12 \g refer (i.e., where @var{object-map}s point to).
173 : anton 1.3 dup interface-map 2@ drop swap interface-map-offset @ + ;
174 :    
175 :     : unique-interface-map ( class-map offset -- )
176 :     \ if the interface at offset in class map is the same as its parent,
177 :     \ copy it to make it unique; used for implementing a copy-on-write policy
178 :     over @ class-parent @ class->map ( class-map offset parent-map )
179 :     over + @ >r \ the map for the interface for the parent
180 : anton 1.9 + dup @ ( interface-mapp interface-map )
181 : anton 1.3 dup r> =
182 :     if
183 : anton 1.9 dup @ interface-map 2@ nip save-mem drop
184 : anton 1.3 swap !
185 :     else
186 :     2drop
187 :     then ;
188 :    
189 : anton 1.10 : class-override! ( xt sel-xt class-map -- ) \ objects- objects
190 : crook 1.12 \g @var{xt} is the new method for the selector @var{sel-xt} in
191 :     \g @var{class-map}.
192 : anton 1.3 over >body ( xt sel-xt class-map selector-body )
193 :     selector-interface @ ( xt sel-xt class-map offset )
194 :     ?dup-if \ the selector is for an interface
195 :     2dup unique-interface-map
196 :     + @
197 :     then
198 :     interface-override! ;
199 : anton 1.1
200 : anton 1.10 : overrides ( xt "selector" -- ) \ objects- objects
201 : crook 1.12 \g replace default method for @var{selector} in the current class
202 :     \g with @var{xt}. @code{overrides} must not be used during an
203 : anton 1.6 \g interface definition.
204 : anton 1.3 ' current-interface @ class->map class-override! ;
205 :    
206 :     \ interfaces
207 :    
208 :     \ every interface gets a different offset; the latest one is stored here
209 :     variable last-interface-offset 0 last-interface-offset !
210 :    
211 : anton 1.10 : interface ( -- ) \ objects- objects
212 : crook 1.12 \g Start an interface definition.
213 : anton 1.4 interface% %allot >r
214 : anton 1.8 r@ current-interface !
215 :     current-interface 1 cells save-mem r@ interface-map 2!
216 : anton 1.3 -1 cells last-interface-offset +!
217 :     last-interface-offset @ r@ interface-offset !
218 : anton 1.8 0 r> interface-map-offset ! ;
219 : anton 1.3
220 : anton 1.10 : end-interface-noname ( -- interface ) \ objects- objects
221 : crook 1.12 \g End an interface definition. The resulting interface is
222 :     \g @var{interface}.
223 : anton 1.3 current-interface @ ;
224 :    
225 : anton 1.10 : end-interface ( "name" -- ) \ objects- objects
226 : anton 1.6 \g @code{name} execution: @code{-- interface}@*
227 : crook 1.12 \g End an interface definition. The resulting interface is
228 :     \g @var{interface}.
229 : anton 1.3 end-interface-noname constant ;
230 :    
231 :     \ classes
232 :    
233 :     : add-class-order ( n1 class -- wid1 ... widn n+n1 )
234 :     dup >r class-parent @
235 :     ?dup-if
236 :     recurse \ first add the search order for the parent class
237 :     then
238 :     r> class-wordlist @ swap 1+ ;
239 :    
240 : anton 1.10 : push-order ( class -- ) \ objects- objects
241 : crook 1.12 \g Add @var{class}'s wordlists to the head of the search-order.
242 : anton 1.3 >r get-order r> add-class-order set-order ;
243 :    
244 : anton 1.10 : class ( parent-class -- align offset ) \ objects- objects
245 : crook 1.12 \g Start a new class definition as a child of
246 :     \g @var{parent-class}. @var{align offset} are for use by
247 :     \g @var{field} etc.
248 : anton 1.4 class% %allot >r
249 : anton 1.3 dup interface-map 2@ save-mem r@ interface-map 2!
250 :     dup interface-map-offset @ r@ interface-map-offset !
251 :     r@ dup class->map !
252 :     0 r@ interface-offset !
253 :     dup r@ class-parent !
254 :     wordlist r@ class-wordlist !
255 :     r@ current-interface !
256 :     r> push-order
257 :     class-inst-size 2@ ;
258 :    
259 :     : remove-class-order ( wid1 ... widn n+n1 class -- n1 )
260 :     \ note: no checks, whether the wordlists are correct
261 :     begin
262 :     >r nip 1-
263 :     r> class-parent @ dup 0=
264 :     until
265 :     drop ;
266 :    
267 : anton 1.10 : drop-order ( class -- ) \ objects- objects
268 : crook 1.12 \g Drop @var{class}'s wordlists from the search order. No
269 :     \g checking is made whether @var{class}'s wordlists are actually
270 : anton 1.6 \g on the search order.
271 : anton 1.3 >r get-order r> remove-class-order set-order ;
272 :    
273 : anton 1.10 : end-class-noname ( align offset -- class ) \ objects- objects
274 : crook 1.12 \g End a class definition. The resulting class is @var{class}.
275 : anton 1.3 current-interface @ dup drop-order class-inst-size 2!
276 :     end-interface-noname ;
277 :    
278 : anton 1.10 : end-class ( align offset "name" -- ) \ objects- objects
279 : crook 1.12 \g @var{name} execution: @code{-- class}@*
280 :     \g End a class definition. The resulting class is @var{class}.
281 : anton 1.3 \ name execution: ( -- class )
282 :     end-class-noname constant ;
283 : anton 1.1
284 : anton 1.3 \ visibility control
285 :    
286 :     variable public-wordlist
287 :    
288 : anton 1.10 : protected ( -- ) \ objects- objects
289 : crook 1.12 \g Set the compilation wordlist to the current class's wordlist
290 : anton 1.3 current-interface @ class-wordlist @
291 :     dup get-current <>
292 : anton 1.4 if \ we are not protected already
293 : anton 1.3 get-current public-wordlist !
294 :     then
295 :     set-current ;
296 :    
297 : anton 1.10 : public ( -- ) \ objects- objects
298 : crook 1.12 \g Restore the compilation wordlist that was in effect before the
299 : anton 1.6 \g last @code{protected} that actually changed the compilation
300 :     \g wordlist.
301 : anton 1.3 public-wordlist @ set-current ;
302 :    
303 :     \ classes that implement interfaces
304 :    
305 :     : front-extend-mem ( addr1 u1 u -- addr addr2 u2 )
306 : crook 1.12 \ Extend memory block allocated from the heap by u aus, with the
307 : anton 1.3 \ old stuff coming at the end
308 :     2dup + dup >r allocate throw ( addr1 u1 u addr2 ; R: u2 )
309 :     dup >r + >r over r> rot move ( addr1 ; R: u2 addr2 )
310 :     free throw
311 :     r> dup r> ;
312 :    
313 : anton 1.10 : implementation ( interface -- ) \ objects- objects
314 : crook 1.12 \g The current class implements @var{interface}. I.e., you can
315 : anton 1.6 \g use all selectors of the interface in the current class and its
316 :     \g descendents.
317 : anton 1.3 dup interface-offset @ ( interface offset )
318 :     current-interface @ interface-map-offset @ negate over - dup 0>
319 :     if \ the interface does not fit in the present class-map
320 :     >r current-interface @ interface-map 2@
321 :     r@ front-extend-mem
322 :     current-interface @ interface-map 2!
323 :     r@ erase
324 :     dup negate current-interface @ interface-map-offset !
325 :     r>
326 :     then ( interface offset n )
327 :     drop >r
328 :     interface-map 2@ save-mem drop ( map )
329 :     current-interface @ dup interface-map 2@ drop
330 :     swap interface-map-offset @ + r> + ! ;
331 : anton 1.1
332 :     \ this/self, instance variables etc.
333 :    
334 : anton 1.3 \ rename "this" into "self" if you are a Smalltalk fiend
335 : anton 1.10 0 value this ( -- object ) \ objects- objects
336 : anton 1.6 \g the receiving object of the current method (aka active object).
337 : anton 1.10 : to-this ( object -- ) \ objects- objects
338 : crook 1.12 \g Set @code{this} (used internally, but useful when debugging).
339 : anton 1.3 TO this ;
340 :    
341 :     \ another implementation, if you don't have (fast) values
342 :     \ variable thisp
343 :     \ : this ( -- object )
344 :     \ thisp @ ;
345 :     \ : to-this ( object -- )
346 :     \ thisp ! ;
347 : anton 1.1
348 : anton 1.10 : m: ( -- xt colon-sys; run-time: object -- ) \ objects- objects
349 : crook 1.12 \g Start a method definition; @var{object} becomes new @code{this}.
350 : anton 1.1 :noname
351 :     POSTPONE this
352 :     POSTPONE >r
353 : anton 1.3 POSTPONE to-this ;
354 : anton 1.1
355 : anton 1.10 : exitm ( -- ) \ objects- objects
356 : anton 1.6 \g @code{exit} from a method; restore old @code{this}.
357 : anton 1.5 POSTPONE r>
358 :     POSTPONE to-this
359 :     POSTPONE exit ; immediate
360 :    
361 : anton 1.10 : ;m ( colon-sys --; run-time: -- ) \ objects- objects
362 : crook 1.12 \g End a method definition; restore old @code{this}.
363 : anton 1.1 POSTPONE r>
364 : anton 1.3 POSTPONE to-this
365 : anton 1.1 POSTPONE ; ; immediate
366 :    
367 : anton 1.7 : catch ( ... xt -- ... n ) \ exception
368 : crook 1.12 \ Make it safe to call CATCH within a method.
369 : anton 1.1 \ should also be done with all words containing CATCH.
370 : anton 1.3 this >r catch r> to-this ;
371 :    
372 :     \ the following is a bit roundabout; this is caused by the standard
373 :     \ disallowing to change the compilation wordlist between CREATE and
374 :     \ DOES> (see RFI 3)
375 :    
376 : anton 1.4 : inst-something ( align1 size1 align size xt "name" -- align2 size2 )
377 : anton 1.3 \ xt ( -- ) typically is for a DOES>-word
378 :     get-current >r
379 :     current-interface @ class-wordlist @ set-current
380 :     >r create-field r> execute
381 :     r> set-current ;
382 : anton 1.1
383 : anton 1.3 : do-inst-var ( -- )
384 :     does> \ name execution: ( -- addr )
385 : anton 1.1 ( addr1 ) @ this + ;
386 :    
387 : anton 1.10 : inst-var ( align1 offset1 align size "name" -- align2 offset2 ) \ objects- objects
388 : crook 1.12 \g @var{name} execution: @code{-- addr}@*
389 :     \g @var{addr} is the address of the field @var{name} in
390 : anton 1.6 \g @code{this} object.
391 : anton 1.3 ['] do-inst-var inst-something ;
392 :    
393 :     : do-inst-value ( -- )
394 :     does> \ name execution: ( -- w )
395 :     ( addr1 ) @ this + @ ;
396 :    
397 : anton 1.10 : inst-value ( align1 offset1 "name" -- align2 offset2 ) \ objects- objects
398 : crook 1.12 \g @var{name} execution: @code{-- w}@*
399 :     \g @var{w} is the value of the field @var{name} in @code{this}
400 : anton 1.6 \g object.
401 : anton 1.4 cell% ['] do-inst-value inst-something ;
402 : anton 1.3
403 : anton 1.10 : <to-inst> ( w xt -- ) \ objects- objects
404 : crook 1.12 \g store @var{w} into the field @var{xt} in @code{this} object.
405 : anton 1.3 >body @ this + ! ;
406 :    
407 : anton 1.10 : [to-inst] ( compile-time: "name" -- ; run-time: w -- ) \ objects- objects
408 : crook 1.12 \g store @var{w} into field @var{name} in @code{this} object.
409 : anton 1.3 ' >body @ POSTPONE literal
410 :     POSTPONE this
411 :     POSTPONE +
412 :     POSTPONE ! ; immediate
413 :    
414 : anton 1.4 \ class binding stuff
415 : anton 1.1
416 : anton 1.10 : <bind> ( class selector-xt -- xt ) \ objects- objects
417 : crook 1.12 \g @var{xt} is the method for the selector @var{selector-xt} in
418 :     \g @var{class}.
419 : anton 1.3 >body swap class->map over selector-interface @
420 :     ?dup-if
421 :     + @
422 :     then
423 :     swap selector-offset @ + @ ;
424 : anton 1.1
425 : anton 1.10 : bind' ( "class" "selector" -- xt ) \ objects- objects
426 : crook 1.12 \g @var{xt} is the method for @var{selector} in @var{class}.
427 : anton 1.3 ' execute ' <bind> ;
428 : anton 1.1
429 : anton 1.10 : bind ( ... "class" "selector" -- ... ) \ objects- objects
430 : crook 1.12 \g Execute the method for @var{selector} in @var{class}.
431 : anton 1.1 bind' execute ;
432 :    
433 : anton 1.10 : [bind] ( compile-time: "class" "selector" -- ; run-time: ... object -- ... ) \ objects- objects
434 : crook 1.12 \g Compile the method for @var{selector} in @var{class}.
435 : anton 1.1 bind' compile, ; immediate
436 :    
437 : anton 1.10 : current' ( "selector" -- xt ) \ objects- objects
438 : crook 1.12 \g @var{xt} is the method for @var{selector} in the current class.
439 : anton 1.4 current-interface @ ' <bind> ;
440 :    
441 : anton 1.10 : [current] ( compile-time: "selector" -- ; run-time: ... object -- ... ) \ objects- objects
442 : crook 1.12 \g Compile the method for @var{selector} in the current class.
443 : anton 1.4 current' compile, ; immediate
444 :    
445 : anton 1.10 : [parent] ( compile-time: "selector" -- ; run-time: ... object -- ... ) \ objects- objects
446 : crook 1.12 \g Compile the method for @var{selector} in the parent of the
447 : anton 1.6 \g current class.
448 : anton 1.3 current-interface @ class-parent @ ' <bind> compile, ; immediate
449 :    
450 : anton 1.1 \ the object class
451 :    
452 : anton 1.3 \ because OBJECT has no parent class, we have to build it by hand
453 :     \ (instead of with class)
454 :    
455 : anton 1.4 class% %allot current-interface !
456 :     current-interface 1 cells save-mem current-interface @ interface-map 2!
457 :     0 current-interface @ interface-map-offset !
458 :     0 current-interface @ interface-offset !
459 :     0 current-interface @ class-parent !
460 :     wordlist current-interface @ class-wordlist !
461 :     object%
462 :     current-interface @ push-order
463 : anton 1.3
464 : anton 1.5 ' drop ( object -- )
465 : anton 1.10 method construct ( ... object -- ) \ objects- objects
466 : crook 1.12 \g Initialize the data fields of @var{object}. The method for the
467 :     \g class @var{object} just does nothing: @code{( object -- )}.
468 : anton 1.3
469 :     :noname ( object -- )
470 :     ." object:" dup . ." class:" object-map @ @ . ;
471 : anton 1.10 method print ( object -- ) \ objects- objects
472 : crook 1.12 \g Print the object. The method for the class @var{object} prints
473 : anton 1.6 \g the address of the object and the address of its class.
474 : anton 1.3
475 : anton 1.10 end-class object ( -- class ) \ objects- objects
476 : anton 1.6 \g the ancestor of all classes.
477 : anton 1.1
478 : anton 1.3 \ constructing objects
479 : anton 1.1
480 : anton 1.10 : init-object ( ... class object -- ) \ objects- objects
481 : crook 1.12 \g Initialize a chunk of memory (@var{object}) to an object of
482 :     \g class @var{class}; then performs @code{construct}.
483 : anton 1.3 swap class->map over object-map ! ( ... object )
484 :     construct ;
485 :    
486 : anton 1.10 : xt-new ( ... class xt -- object ) \ objects- objects
487 : crook 1.12 \g Make a new object, using @code{xt ( align size -- addr )} to
488 : anton 1.6 \g get memory.
489 : anton 1.3 over class-inst-size 2@ rot execute
490 :     dup >r init-object r> ;
491 :    
492 : anton 1.10 : dict-new ( ... class -- object ) \ objects- objects
493 : crook 1.12 \g @code{allot} and initialize an object of class @var{class} in
494 : anton 1.6 \g the dictionary.
495 : anton 1.4 ['] %allot xt-new ;
496 : anton 1.3
497 : anton 1.10 : heap-new ( ... class -- object ) \ objects- objects
498 : crook 1.12 \g @code{allocate} and initialize an object of class @var{class}.
499 : anton 1.4 ['] %alloc xt-new ;

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