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\ @(#) condcomp.fth 98/01/26 1.2
\ Conditional Compilation support
\
\ Words: STRINGS= [IF] [ELSE] [THEN] EXISTS?
\
\ Lifted from X3J14 dpANS-6 document.
anew task-condcomp.fth
: [ELSE] ( -- )
1
BEGIN \ level
BEGIN
BL WORD \ level $word
COUNT DUP \ level adr len len
WHILE \ level adr len
2DUP S" [IF]" COMPARE 0=
IF \ level adr len
2DROP 1+ \ level'
ELSE \ level adr len
2DUP S" [ELSE]"
COMPARE 0= \ level adr len flag
IF \ level adr len
2DROP 1- DUP IF 1+ THEN \ level'
ELSE \ level adr len
S" [THEN]" COMPARE 0=
IF
1- \ level'
THEN
THEN
THEN
?DUP 0= IF EXIT THEN \ level'
REPEAT 2DROP \ level
REFILL 0= UNTIL \ level
DROP
; IMMEDIATE
: [IF] ( flag -- )
0=
IF POSTPONE [ELSE]
THEN
; IMMEDIATE
: [THEN] ( -- )
; IMMEDIATE
: EXISTS? ( <name> -- flag , true if defined )
bl word find
swap drop
; immediate
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