RosettaCodeData/Task/Execute-a-Markov-algorithm/REXX/execute-a-markov-algorithm....

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3.6 KiB
Rexx

/*REXX program executes a Markov algorithm(s) against specified entries. */
parse arg low high . /*allows which ruleset to process. */
if low=='' | low=="," then low=1 /*Not specified? Then use the default.*/
if high=='' | high=="," then high=6 /* " " " " " " */
tellE= low<0; tellR= high<0 /*flags: used to display file contents.*/
call readEntry
do j=abs(low) to abs(high) /*process each of these rulesets. */
call readRules j /*read a particular ruleset. */
call execRules j /*execute " " " */
say 'result for ruleset' j "───►" !.j
end /*j*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
execRules: parse arg q .; if tellE | tellR then say /*show a blank line?*/
do f=1
do k=1 while @.k\==''; if left(@.k, 1)=='#' | @.k='' then iterate
parse var @.k a ' ->' b /*obtain the A & B parts from rule.*/
a=strip(a); b=strip(b) /*strip leading and/or trailing blanks.*/
fullstop= left(b, 1)==. /*is this a "fullstop" rule? 1≡yes */
if fullstop then b=substr(b, 2) /*purify the B part of the rule. */
old=!.q /*remember the value before the change.*/
!.q=changestr(a, !.q, b) /*implement the ruleset change. */
if fullstop then if old\==!.q then return /*should we stop? */
if old\==!.q then iterate f /*Has Entry changed? Then start over.*/
end /*k*/
return
end /*f*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
readEntry: eFID= 'MARKOV.ENT'; if tellE then say /*show a blank line?*/
!.= /*placeholder for all the test entries.*/
do e=1 while lines(eFID)\==0 /*read the input file until End-Of-File*/
!.e=linein(eFID); if tellE then say 'test entry' e "───►" !.e
end /*e*/ /* [↑] read and maybe echo the entry. */
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
readRules: parse arg ? .; rFID= 'MARKOV_R.'?; if tellR then say /*show a blank line?*/
@.= /*placeholder for all the Markov rules.*/
do r=1 while lines(rFID)\==0 /*read the input file until End-Of-File*/
@.r=linein(rFID); if tellR then say 'ruleSet' ?"."left(r,4) '' @.r
end /*r*/ /* [↑] read and maybe echo the rule. */
return