30 lines
1.1 KiB
Forth
30 lines
1.1 KiB
Forth
\ this is congruent to the previous demonstration, employing
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\ a data structure to store goto/jump addresses instead of
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\ separate variables, and two additional words 'mark_goto' and
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\ 'goto'. works with ficl, pfe, gforth, bigforth, and vfxforth.
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\ swiftforth and iforth crash.
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create gotos 10 cells allot \ data structure for storing goto/jump addresses
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: mark_goto here swap 1- cells gotos + ! ; immediate \ save addresses for jumping
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: goto r> drop 1- cells gotos + @ >r ;
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\ designations for commands are immaterial when using goto's,
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\ since the commands are not referenced by name, and are instead
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\ jumped into by means of the goto marker.
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: command1
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[ 1 ] mark_goto s" item1 " type 7 goto
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[ 2 ] mark_goto s" item2 " type 8 goto
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[ 3 ] mark_goto s" item3 " type 9 goto
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[ 4 ] mark_goto s" item4 " type 10 goto
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[ 5 ] mark_goto s" item5 " type cr 2dup = if 2drop exit then 1+ 6 goto ;
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: command2
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[ 6 ] mark_goto s" line " type dup . s" --> item6 " type 1 goto
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[ 7 ] mark_goto s" item7 " type 2 goto
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[ 8 ] mark_goto s" item8 " type 3 goto
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[ 9 ] mark_goto s" item9 " type 4 goto
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[ 10 ] mark_goto s" item10 " type 5 goto ;
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: go 5 1 6 goto ; go
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bye
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