Annotation of gforth/glocals.fs, revision 1.41
1.15 anton 1: \ A powerful locals implementation
2:
1.38 anton 3: \ Copyright (C) 1995,1996,1997,1998 Free Software Foundation, Inc.
1.15 anton 4:
5: \ This file is part of Gforth.
6:
7: \ Gforth is free software; you can redistribute it and/or
8: \ modify it under the terms of the GNU General Public License
9: \ as published by the Free Software Foundation; either version 2
10: \ of the License, or (at your option) any later version.
11:
12: \ This program is distributed in the hope that it will be useful,
13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: \ GNU General Public License for more details.
16:
17: \ You should have received a copy of the GNU General Public License
18: \ along with this program; if not, write to the Free Software
19: \ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20:
21:
1.16 anton 22: \ More documentation can be found in the manual and in
23: \ http://www.complang.tuwien.ac.at/papers/ertl94l.ps.gz
24:
1.1 anton 25: \ Local variables are quite important for writing readable programs, but
26: \ IMO (anton) they are the worst part of the standard. There they are very
27: \ restricted and have an ugly interface.
28:
29: \ So, we implement the locals wordset, but do not recommend using
30: \ locals-ext (which is a really bad user interface for locals).
31:
32: \ We also have a nice and powerful user-interface for locals: locals are
33: \ defined with
34:
35: \ { local1 local2 ... }
36: \ or
37: \ { local1 local2 ... -- ... }
38: \ (anything after the -- is just a comment)
39:
40: \ Every local in this list consists of an optional type specification
41: \ and a name. If there is only the name, it stands for a cell-sized
42: \ value (i.e., you get the value of the local variable, not it's
43: \ address). The following type specifiers stand before the name:
44:
45: \ Specifier Type Access
46: \ W: Cell value
47: \ W^ Cell address
48: \ D: Double value
49: \ D^ Double address
50: \ F: Float value
51: \ F^ Float address
52: \ C: Char value
53: \ C^ Char address
54:
55: \ The local variables are initialized with values from the appropriate
56: \ stack. In contrast to the examples in the standard document our locals
57: \ take the arguments in the expected way: The last local gets the top of
58: \ stack, the second last gets the second stack item etc. An example:
59:
60: \ : CX* { F: Ar F: Ai F: Br F: Bi -- Cr Ci }
61: \ \ complex multiplication
62: \ Ar Br f* Ai Bi f* f-
63: \ Ar Bi f* Ai Br f* f+ ;
64:
65: \ There will also be a way to add user types, but it is not yet decided,
66: \ how. Ideas are welcome.
67:
68: \ Locals defined in this manner live until (!! see below).
69: \ Their names can be used during this time to get
70: \ their value or address; The addresses produced in this way become
71: \ invalid at the end of the lifetime.
72:
73: \ Values can be changed with TO, but this is not recomended (TO is a
74: \ kludge and words lose the single-assignment property, which makes them
75: \ harder to analyse).
76:
77: \ As for the internals, we use a special locals stack. This eliminates
78: \ the problems and restrictions of reusing the return stack and allows
79: \ to store floats as locals: the return stack is not guaranteed to be
80: \ aligned correctly, but our locals stack must be float-aligned between
81: \ words.
82:
83: \ Other things about the internals are pretty unclear now.
84:
85: \ Currently locals may only be
86: \ defined at the outer level and TO is not supported.
87:
1.33 anton 88: require search.fs
1.14 anton 89: require float.fs
1.1 anton 90:
1.14 anton 91: : compile-@local ( n -- ) \ gforth compile-fetch-local
1.3 anton 92: case
1.7 pazsan 93: 0 of postpone @local0 endof
94: 1 cells of postpone @local1 endof
95: 2 cells of postpone @local2 endof
96: 3 cells of postpone @local3 endof
1.3 anton 97: ( otherwise ) dup postpone @local# ,
98: endcase ;
99:
1.14 anton 100: : compile-f@local ( n -- ) \ gforth compile-f-fetch-local
1.3 anton 101: case
1.7 pazsan 102: 0 of postpone f@local0 endof
103: 1 floats of postpone f@local1 endof
1.3 anton 104: ( otherwise ) dup postpone f@local# ,
105: endcase ;
106:
1.27 pazsan 107: \ locals stuff needed for control structures
108:
109: : compile-lp+! ( n -- ) \ gforth compile-l-p-plus-store
110: dup negate locals-size +!
111: 0 over = if
112: else -1 cells over = if postpone lp-
113: else 1 floats over = if postpone lp+
114: else 2 floats over = if postpone lp+2
115: else postpone lp+!# dup ,
116: then then then then drop ;
117:
118: : adjust-locals-size ( n -- ) \ gforth
119: \ sets locals-size to n and generates an appropriate lp+!
120: locals-size @ swap - compile-lp+! ;
121:
1.1 anton 122: \ the locals stack grows downwards (see primitives)
123: \ of the local variables of a group (in braces) the leftmost is on top,
124: \ i.e. by going onto the locals stack the order is reversed.
125: \ there are alignment gaps if necessary.
126: \ lp must have the strictest alignment (usually float) across calls;
127: \ for simplicity we align it strictly for every group.
128:
1.5 anton 129: slowvoc @
130: slowvoc on \ we want a linked list for the vocabulary locals
1.1 anton 131: vocabulary locals \ this contains the local variables
1.37 pazsan 132: ' locals >body wordlist-id ' locals-list >body !
1.5 anton 133: slowvoc !
1.1 anton 134:
135: create locals-buffer 1000 allot \ !! limited and unsafe
136: \ here the names of the local variables are stored
137: \ we would have problems storing them at the normal dp
138:
139: variable locals-dp \ so here's the special dp for locals.
140:
141: : alignlp-w ( n1 -- n2 )
142: \ cell-align size and generate the corresponding code for aligning lp
1.3 anton 143: aligned dup adjust-locals-size ;
1.1 anton 144:
145: : alignlp-f ( n1 -- n2 )
1.3 anton 146: faligned dup adjust-locals-size ;
1.1 anton 147:
148: \ a local declaration group (the braces stuff) is compiled by calling
149: \ the appropriate compile-pushlocal for the locals, starting with the
150: \ righmost local; the names are already created earlier, the
151: \ compile-pushlocal just inserts the offsets from the frame base.
152:
153: : compile-pushlocal-w ( a-addr -- ) ( run-time: w -- )
154: \ compiles a push of a local variable, and adjusts locals-size
155: \ stores the offset of the local variable to a-addr
156: locals-size @ alignlp-w cell+ dup locals-size !
157: swap !
158: postpone >l ;
159:
1.27 pazsan 160: \ locals list operations
161:
162: : common-list ( list1 list2 -- list3 ) \ gforth-internal
163: \ list1 and list2 are lists, where the heads are at higher addresses than
164: \ the tail. list3 is the largest sublist of both lists.
165: begin
166: 2dup u<>
167: while
168: 2dup u>
169: if
170: swap
171: then
172: @
173: repeat
174: drop ;
175:
176: : sub-list? ( list1 list2 -- f ) \ gforth-internal
177: \ true iff list1 is a sublist of list2
178: begin
179: 2dup u<
180: while
181: @
182: repeat
183: = ;
184:
185: : list-size ( list -- u ) \ gforth-internal
1.36 pazsan 186: \ size of the locals frame represented by list
187: 0 ( list n )
188: begin
189: over 0<>
190: while
191: over
192: ((name>)) >body @ max
193: swap @ swap ( get next )
194: repeat
195: faligned nip ;
1.27 pazsan 196:
197: : set-locals-size-list ( list -- )
1.37 pazsan 198: dup locals-list !
1.36 pazsan 199: list-size locals-size ! ;
1.27 pazsan 200:
201: : check-begin ( list -- )
202: \ warn if list is not a sublist of locals-list
1.37 pazsan 203: locals-list @ sub-list? 0= if
1.27 pazsan 204: \ !! print current position
205: ." compiler was overly optimistic about locals at a BEGIN" cr
206: \ !! print assumption and reality
207: then ;
208:
1.1 anton 209: : compile-pushlocal-f ( a-addr -- ) ( run-time: f -- )
210: locals-size @ alignlp-f float+ dup locals-size !
211: swap !
212: postpone f>l ;
213:
214: : compile-pushlocal-d ( a-addr -- ) ( run-time: w1 w2 -- )
215: locals-size @ alignlp-w cell+ cell+ dup locals-size !
216: swap !
217: postpone swap postpone >l postpone >l ;
218:
219: : compile-pushlocal-c ( a-addr -- ) ( run-time: w -- )
1.3 anton 220: -1 chars compile-lp+!
1.1 anton 221: locals-size @ swap !
222: postpone lp@ postpone c! ;
223:
224: : create-local ( " name" -- a-addr )
1.9 anton 225: \ defines the local "name"; the offset of the local shall be
226: \ stored in a-addr
1.1 anton 227: create
1.12 anton 228: immediate restrict
1.1 anton 229: here 0 , ( place for the offset ) ;
230:
1.3 anton 231: : lp-offset ( n1 -- n2 )
232: \ converts the offset from the frame start to an offset from lp and
233: \ i.e., the address of the local is lp+locals_size-offset
234: locals-size @ swap - ;
235:
1.1 anton 236: : lp-offset, ( n -- )
237: \ converts the offset from the frame start to an offset from lp and
238: \ adds it as inline argument to a preceding locals primitive
1.3 anton 239: lp-offset , ;
1.1 anton 240:
241: vocabulary locals-types \ this contains all the type specifyers, -- and }
242: locals-types definitions
243:
1.14 anton 244: : W: ( "name" -- a-addr xt ) \ gforth w-colon
245: create-local
1.1 anton 246: \ xt produces the appropriate locals pushing code when executed
247: ['] compile-pushlocal-w
248: does> ( Compilation: -- ) ( Run-time: -- w )
249: \ compiles a local variable access
1.3 anton 250: @ lp-offset compile-@local ;
1.1 anton 251:
1.14 anton 252: : W^ ( "name" -- a-addr xt ) \ gforth w-caret
253: create-local
1.1 anton 254: ['] compile-pushlocal-w
255: does> ( Compilation: -- ) ( Run-time: -- w )
256: postpone laddr# @ lp-offset, ;
257:
1.14 anton 258: : F: ( "name" -- a-addr xt ) \ gforth f-colon
259: create-local
1.1 anton 260: ['] compile-pushlocal-f
261: does> ( Compilation: -- ) ( Run-time: -- w )
1.3 anton 262: @ lp-offset compile-f@local ;
1.1 anton 263:
1.14 anton 264: : F^ ( "name" -- a-addr xt ) \ gforth f-caret
265: create-local
1.1 anton 266: ['] compile-pushlocal-f
267: does> ( Compilation: -- ) ( Run-time: -- w )
268: postpone laddr# @ lp-offset, ;
269:
1.14 anton 270: : D: ( "name" -- a-addr xt ) \ gforth d-colon
271: create-local
1.1 anton 272: ['] compile-pushlocal-d
273: does> ( Compilation: -- ) ( Run-time: -- w )
274: postpone laddr# @ lp-offset, postpone 2@ ;
275:
1.14 anton 276: : D^ ( "name" -- a-addr xt ) \ gforth d-caret
277: create-local
1.1 anton 278: ['] compile-pushlocal-d
279: does> ( Compilation: -- ) ( Run-time: -- w )
280: postpone laddr# @ lp-offset, ;
281:
1.14 anton 282: : C: ( "name" -- a-addr xt ) \ gforth c-colon
283: create-local
1.1 anton 284: ['] compile-pushlocal-c
285: does> ( Compilation: -- ) ( Run-time: -- w )
286: postpone laddr# @ lp-offset, postpone c@ ;
287:
1.14 anton 288: : C^ ( "name" -- a-addr xt ) \ gforth c-caret
289: create-local
1.1 anton 290: ['] compile-pushlocal-c
291: does> ( Compilation: -- ) ( Run-time: -- w )
292: postpone laddr# @ lp-offset, ;
293:
294: \ you may want to make comments in a locals definitions group:
1.39 crook 295: ' \ alias \ ( -- ) \ core-ext,block-ext backslash
296: \G Line comment: if @code{BLK} contains 0, parse and discard the remainder
297: \G of the parse area. Otherwise, parse and discard all subsequent characters in the
298: \G parse area corresponding to the current line.
299: immediate
300:
301: ' ( alias ( ( compilation 'ccc<close-paren>' -- ; run-time -- ) \ core,file paren
302: \G Comment: parse and discard all subsequent characters in the parse
1.41 ! jwilke 303: \G area until ")" is encountered. During interactive input, an end-of-line
1.39 crook 304: \G also acts as a comment terminator. For file input, it does not; if the
1.41 ! jwilke 305: \G end-of-file is encountered whilst parsing for the ")" delimiter, Gforth
1.39 crook 306: \G will generate a warning.
307: immediate
1.1 anton 308:
309: forth definitions
310:
311: \ the following gymnastics are for declaring locals without type specifier.
312: \ we exploit a feature of our dictionary: every wordlist
313: \ has it's own methods for finding words etc.
314: \ So we create a vocabulary new-locals, that creates a 'w:' local named x
315: \ when it is asked if it contains x.
316:
317: also locals-types
318:
319: : new-locals-find ( caddr u w -- nfa )
320: \ this is the find method of the new-locals vocabulary
321: \ make a new local with name caddr u; w is ignored
322: \ the returned nfa denotes a word that produces what W: produces
323: \ !! do the whole thing without nextname
1.3 anton 324: drop nextname
325: ['] W: >name ;
1.1 anton 326:
327: previous
328:
329: : new-locals-reveal ( -- )
330: true abort" this should not happen: new-locals-reveal" ;
331:
1.22 anton 332: create new-locals-map ( -- wordlist-map )
1.29 anton 333: ' new-locals-find A,
334: ' new-locals-reveal A,
335: ' drop A, \ rehash method
1.34 jwilke 336: ' drop A,
1.1 anton 337:
1.41 ! jwilke 338: new-locals-map mappedwordlist Constant new-locals-wl
! 339:
! 340: \ slowvoc @
! 341: \ slowvoc on
! 342: \ vocabulary new-locals
! 343: \ slowvoc !
! 344: \ new-locals-map ' new-locals >body wordlist-map A! \ !! use special access words
1.1 anton 345:
346: variable old-dpp
347:
348: \ and now, finally, the user interface words
1.32 anton 349: : { ( -- lastxt wid 0 ) \ gforth open-brace
1.1 anton 350: dp old-dpp !
351: locals-dp dpp !
1.32 anton 352: lastxt get-current
1.41 ! jwilke 353: get-order new-locals-wl swap 1+ set-order
1.32 anton 354: also locals definitions locals-types
1.1 anton 355: 0 TO locals-wordlist
356: 0 postpone [ ; immediate
357:
358: locals-types definitions
359:
1.32 anton 360: : } ( lastxt wid 0 a-addr1 xt1 ... -- ) \ gforth close-brace
1.1 anton 361: \ ends locals definitions
362: ] old-dpp @ dpp !
363: begin
364: dup
365: while
366: execute
367: repeat
368: drop
369: locals-size @ alignlp-f locals-size ! \ the strictest alignment
370: previous previous
1.32 anton 371: set-current lastcfa !
1.37 pazsan 372: locals-list 0 wordlist-id - TO locals-wordlist ;
1.1 anton 373:
1.14 anton 374: : -- ( addr wid 0 ... -- ) \ gforth dash-dash
1.1 anton 375: }
1.9 anton 376: [char] } parse 2drop ;
1.1 anton 377:
378: forth definitions
379:
380: \ A few thoughts on automatic scopes for locals and how they can be
381: \ implemented:
382:
383: \ We have to combine locals with the control structures. My basic idea
384: \ was to start the life of a local at the declaration point. The life
385: \ would end at any control flow join (THEN, BEGIN etc.) where the local
386: \ is lot live on both input flows (note that the local can still live in
387: \ other, later parts of the control flow). This would make a local live
388: \ as long as you expected and sometimes longer (e.g. a local declared in
389: \ a BEGIN..UNTIL loop would still live after the UNTIL).
390:
391: \ The following example illustrates the problems of this approach:
392:
393: \ { z }
394: \ if
395: \ { x }
396: \ begin
397: \ { y }
398: \ [ 1 cs-roll ] then
399: \ ...
400: \ until
401:
402: \ x lives only until the BEGIN, but the compiler does not know this
403: \ until it compiles the UNTIL (it can deduce it at the THEN, because at
404: \ that point x lives in no thread, but that does not help much). This is
405: \ solved by optimistically assuming at the BEGIN that x lives, but
406: \ warning at the UNTIL that it does not. The user is then responsible
407: \ for checking that x is only used where it lives.
408:
409: \ The produced code might look like this (leaving out alignment code):
410:
411: \ >l ( z )
412: \ ?branch <then>
413: \ >l ( x )
414: \ <begin>:
415: \ >l ( y )
416: \ lp+!# 8 ( RIP: x,y )
417: \ <then>:
418: \ ...
419: \ lp+!# -4 ( adjust lp to <begin> state )
420: \ ?branch <begin>
421: \ lp+!# 4 ( undo adjust )
422:
423: \ The BEGIN problem also has another incarnation:
424:
425: \ AHEAD
426: \ BEGIN
427: \ x
428: \ [ 1 CS-ROLL ] THEN
429: \ { x }
430: \ ...
431: \ UNTIL
432:
433: \ should be legal: The BEGIN is not a control flow join in this case,
434: \ since it cannot be entered from the top; therefore the definition of x
435: \ dominates the use. But the compiler processes the use first, and since
436: \ it does not look ahead to notice the definition, it will complain
437: \ about it. Here's another variation of this problem:
438:
439: \ IF
440: \ { x }
441: \ ELSE
442: \ ...
443: \ AHEAD
444: \ BEGIN
445: \ x
446: \ [ 2 CS-ROLL ] THEN
447: \ ...
448: \ UNTIL
449:
450: \ In this case x is defined before the use, and the definition dominates
451: \ the use, but the compiler does not know this until it processes the
452: \ UNTIL. So what should the compiler assume does live at the BEGIN, if
453: \ the BEGIN is not a control flow join? The safest assumption would be
454: \ the intersection of all locals lists on the control flow
455: \ stack. However, our compiler assumes that the same variables are live
456: \ as on the top of the control flow stack. This covers the following case:
457:
458: \ { x }
459: \ AHEAD
460: \ BEGIN
461: \ x
462: \ [ 1 CS-ROLL ] THEN
463: \ ...
464: \ UNTIL
465:
466: \ If this assumption is too optimistic, the compiler will warn the user.
467:
1.28 anton 468: \ Implementation:
1.1 anton 469:
1.3 anton 470: \ explicit scoping
1.1 anton 471:
1.14 anton 472: : scope ( compilation -- scope ; run-time -- ) \ gforth
1.36 pazsan 473: cs-push-part scopestart ; immediate
474:
475: : adjust-locals-list ( wid -- )
1.37 pazsan 476: locals-list @ common-list
1.36 pazsan 477: dup list-size adjust-locals-size
1.37 pazsan 478: locals-list ! ;
1.3 anton 479:
1.14 anton 480: : endscope ( compilation scope -- ; run-time -- ) \ gforth
1.36 pazsan 481: scope?
482: drop adjust-locals-list ; immediate
1.1 anton 483:
1.3 anton 484: \ adapt the hooks
1.1 anton 485:
1.3 anton 486: : locals-:-hook ( sys -- sys addr xt n )
487: \ addr is the nfa of the defined word, xt its xt
1.1 anton 488: DEFERS :-hook
489: last @ lastcfa @
490: clear-leave-stack
491: 0 locals-size !
492: locals-buffer locals-dp !
1.37 pazsan 493: 0 locals-list !
1.3 anton 494: dead-code off
495: defstart ;
1.1 anton 496:
1.3 anton 497: : locals-;-hook ( sys addr xt sys -- sys )
498: def?
1.1 anton 499: 0 TO locals-wordlist
1.3 anton 500: 0 adjust-locals-size ( not every def ends with an exit )
1.1 anton 501: lastcfa ! last !
502: DEFERS ;-hook ;
503:
1.28 anton 504: \ THEN (another control flow from before joins the current one):
505: \ The new locals-list is the intersection of the current locals-list and
506: \ the orig-local-list. The new locals-size is the (alignment-adjusted)
507: \ size of the new locals-list. The following code is generated:
508: \ lp+!# (current-locals-size - orig-locals-size)
509: \ <then>:
510: \ lp+!# (orig-locals-size - new-locals-size)
511:
512: \ Of course "lp+!# 0" is not generated. Still this is admittedly a bit
513: \ inefficient, e.g. if there is a locals declaration between IF and
514: \ ELSE. However, if ELSE generates an appropriate "lp+!#" before the
515: \ branch, there will be none after the target <then>.
516:
1.30 anton 517: : (then-like) ( orig -- )
518: dead-orig =
1.27 pazsan 519: if
1.30 anton 520: >resolve drop
1.27 pazsan 521: else
522: dead-code @
523: if
1.30 anton 524: >resolve set-locals-size-list dead-code off
1.27 pazsan 525: else \ both live
1.30 anton 526: over list-size adjust-locals-size
527: >resolve
1.36 pazsan 528: adjust-locals-list
1.27 pazsan 529: then
530: then ;
531:
532: : (begin-like) ( -- )
533: dead-code @ if
534: \ set up an assumption of the locals visible here. if the
535: \ users want something to be visible, they have to declare
536: \ that using ASSUME-LIVE
537: backedge-locals @ set-locals-size-list
538: then
539: dead-code off ;
540:
541: \ AGAIN (the current control flow joins another, earlier one):
542: \ If the dest-locals-list is not a subset of the current locals-list,
543: \ issue a warning (see below). The following code is generated:
544: \ lp+!# (current-local-size - dest-locals-size)
545: \ branch <begin>
546:
547: : (again-like) ( dest -- addr )
548: over list-size adjust-locals-size
549: swap check-begin POSTPONE unreachable ;
550:
551: \ UNTIL (the current control flow may join an earlier one or continue):
552: \ Similar to AGAIN. The new locals-list and locals-size are the current
553: \ ones. The following code is generated:
554: \ ?branch-lp+!# <begin> (current-local-size - dest-locals-size)
555:
556: : (until-like) ( list addr xt1 xt2 -- )
557: \ list and addr are a fragment of a cs-item
558: \ xt1 is the conditional branch without lp adjustment, xt2 is with
559: >r >r
560: locals-size @ 2 pick list-size - dup if ( list dest-addr adjustment )
561: r> drop r> compile,
562: swap <resolve ( list adjustment ) ,
563: else ( list dest-addr adjustment )
564: drop
565: r> compile, <resolve
566: r> drop
567: then ( list )
568: check-begin ;
569:
570: : (exit-like) ( -- )
571: 0 adjust-locals-size ;
572:
1.1 anton 573: ' locals-:-hook IS :-hook
574: ' locals-;-hook IS ;-hook
1.27 pazsan 575:
576: ' (then-like) IS then-like
577: ' (begin-like) IS begin-like
578: ' (again-like) IS again-like
579: ' (until-like) IS until-like
580: ' (exit-like) IS exit-like
1.1 anton 581:
582: \ The words in the locals dictionary space are not deleted until the end
583: \ of the current word. This is a bit too conservative, but very simple.
584:
585: \ There are a few cases to consider: (see above)
586:
587: \ after AGAIN, AHEAD, EXIT (the current control flow is dead):
588: \ We have to special-case the above cases against that. In this case the
589: \ things above are not control flow joins. Everything should be taken
590: \ over from the live flow. No lp+!# is generated.
591:
592: \ About warning against uses of dead locals. There are several options:
593:
594: \ 1) Do not complain (After all, this is Forth;-)
595:
596: \ 2) Additional restrictions can be imposed so that the situation cannot
597: \ arise; the programmer would have to introduce explicit scoping
598: \ declarations in cases like the above one. I.e., complain if there are
599: \ locals that are live before the BEGIN but not before the corresponding
600: \ AGAIN (replace DO etc. for BEGIN and UNTIL etc. for AGAIN).
601:
602: \ 3) The real thing: i.e. complain, iff a local lives at a BEGIN, is
603: \ used on a path starting at the BEGIN, and does not live at the
604: \ corresponding AGAIN. This is somewhat hard to implement. a) How does
605: \ the compiler know when it is working on a path starting at a BEGIN
606: \ (consider "{ x } if begin [ 1 cs-roll ] else x endif again")? b) How
607: \ is the usage info stored?
608:
609: \ For now I'll resort to alternative 2. When it produces warnings they
610: \ will often be spurious, but warnings should be rare. And better
611: \ spurious warnings now and then than days of bug-searching.
612:
613: \ Explicit scoping of locals is implemented by cs-pushing the current
614: \ locals-list and -size (and an unused cell, to make the size equal to
615: \ the other entries) at the start of the scope, and restoring them at
616: \ the end of the scope to the intersection, like THEN does.
617:
618:
619: \ And here's finally the ANS standard stuff
620:
1.14 anton 621: : (local) ( addr u -- ) \ local paren-local-paren
1.3 anton 622: \ a little space-inefficient, but well deserved ;-)
623: \ In exchange, there are no restrictions whatsoever on using (local)
1.4 anton 624: \ as long as you use it in a definition
1.3 anton 625: dup
626: if
627: nextname POSTPONE { [ also locals-types ] W: } [ previous ]
628: else
629: 2drop
630: endif ;
1.1 anton 631:
1.4 anton 632: : >definer ( xt -- definer )
633: \ this gives a unique identifier for the way the xt was defined
634: \ words defined with different does>-codes have different definers
635: \ the definer can be used for comparison and in definer!
1.30 anton 636: dup >does-code
637: ?dup-if
638: nip 1 or
1.4 anton 639: else
640: >code-address
641: then ;
642:
643: : definer! ( definer xt -- )
644: \ gives the word represented by xt the behaviour associated with definer
645: over 1 and if
1.13 anton 646: swap [ 1 invert ] literal and does-code!
1.4 anton 647: else
648: code-address!
649: then ;
650:
1.23 pazsan 651: :noname
1.31 anton 652: ' dup >definer [ ' locals-wordlist ] literal >definer =
1.23 pazsan 653: if
654: >body !
655: else
656: -&32 throw
657: endif ;
658: :noname
1.21 anton 659: 0 0 0. 0.0e0 { c: clocal w: wlocal d: dlocal f: flocal }
1.28 anton 660: comp' drop dup >definer
1.21 anton 661: case
1.30 anton 662: [ ' locals-wordlist ] literal >definer \ value
1.21 anton 663: OF >body POSTPONE Aliteral POSTPONE ! ENDOF
1.35 anton 664: \ !! dependent on c: etc. being does>-defining words
665: \ this works, because >definer uses >does-code in this case,
666: \ which produces a relocatable address
667: [ comp' clocal drop >definer ] literal
1.21 anton 668: OF POSTPONE laddr# >body @ lp-offset, POSTPONE c! ENDOF
1.35 anton 669: [ comp' wlocal drop >definer ] literal
1.21 anton 670: OF POSTPONE laddr# >body @ lp-offset, POSTPONE ! ENDOF
1.35 anton 671: [ comp' dlocal drop >definer ] literal
1.21 anton 672: OF POSTPONE laddr# >body @ lp-offset, POSTPONE 2! ENDOF
1.35 anton 673: [ comp' flocal drop >definer ] literal
1.21 anton 674: OF POSTPONE laddr# >body @ lp-offset, POSTPONE f! ENDOF
675: -&32 throw
1.23 pazsan 676: endcase ;
1.24 anton 677: interpret/compile: TO ( c|w|d|r "name" -- ) \ core-ext,local
1.1 anton 678:
1.6 pazsan 679: : locals|
1.14 anton 680: \ don't use 'locals|'! use '{'! A portable and free '{'
1.21 anton 681: \ implementation is compat/anslocals.fs
1.8 anton 682: BEGIN
683: name 2dup s" |" compare 0<>
684: WHILE
685: (local)
686: REPEAT
1.14 anton 687: drop 0 (local) ; immediate restrict
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