\ Structural Conditionals, based on branches 12dec92py
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: ?struc ( flag -- ) abort" unstructured " ;
: sys? ( sys -- ) dup 0= ?struc ;
: >mark ( -- sys ) here cell allot ;
: >resolve ( sys -- ) here swap
[ has? flash [IF] ] flash! [ [ELSE] ] ! [ [THEN] ] ;
: <resolve ( sys -- ) , ;
: BUT sys? swap ; immediate restrict
: YET sys? dup ; immediate restrict
\ Structural Conditionals 12dec92py
: AHEAD postpone branch >mark ; immediate restrict
: IF postpone ?branch >mark ; immediate restrict
: THEN sys? ( dup @ ?struc ) >resolve ; immediate restrict
: ELSE sys? postpone AHEAD swap postpone THEN ;
' THEN Alias ENDIF immediate restrict
: BEGIN here ; immediate restrict
: WHILE sys? postpone IF swap ; immediate restrict
: AGAIN sys? postpone branch <resolve ; immediate restrict
: UNTIL sys? postpone ?branch <resolve ; immediate restrict
: REPEAT over 0= ?struc postpone AGAIN postpone THEN ;
0 CONSTANT case ( compilation -- case-sys ; run-time -- ) \ core-ext
: of ( compilation -- of-sys ; run-time x1 x2 -- |x1 ) \ core-ext
\ !! the implementation does not match the stack effect
postpone over postpone = postpone if postpone drop
r> ; immediate
: endof ( compilation case-sys1 of-sys -- case-sys2 ; run-time -- ) \ core-ext end-of
>r postpone else r> ; immediate
: endcase ( compilation case-sys -- ; run-time x -- ) \ core-ext end-case
0 ?do postpone then loop ; immediate