Just in time processing on a character stream: Difference between revisions

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(→‎{{header|REXX}}: added the REXX language. -- ~~~~)
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This task was inspired by the movie "[[wp:National_Treasure_%28film%29|National Treasure]]" with refers to a "[[wp:Book cipher|book cipher]]".
This task was inspired by the movie "[[wp:National_Treasure_%28film%29|National Treasure]]" with refers to a "[[wp:Book cipher|book cipher]]".

=={{header|REXX}}==

<lang rexx>/*REXX pgm extracts characters by using a book cipher from a text file. */
parse arg iFID /*optional name of file (book). */
if iFID=='' then iFID="JIT.TXT" /*Not specified? Then use default*/
errTxt= ' is missing or not a positive integer: ' /*error text string.*/
$='abcdefghijklmnopqrstuvwxyz'; _=$; upper _; $= '0123456789'$ || _
ask='──────────enter four parameters (all positive integers) or QUIT'
pag=1; lin=1; @.= /*assume start of page 1, line 1.*/
/*read the entire book from file.*/
do while lines(iFID)\==0 /*process lines from input stream*/
_=translate(linein(iFID),,'9'x) /*obtain a single line from input*/
if pos('c'x,_)\==0 then do /*was a ff (form-feed) detected? */
pag=pag+1 /*bump page counter for next page*/
lin=1 /*reset the line counter to one. */
end /* [↑] handle finding of formfeed*/
@.pag.lin=_ /*obtain a single line from input*/
lin=lin+1 /*bump the line counter. */
end /*while lines···*/ /* [↑] read entire input stream.*/
?= /*define the phrase to be null.*/
do prompt=0; bad=1 /*get J.I.T. positional numbers. */
say ask; pull y /*obtain the numbers from console*/
if y='QUIT' then exit 0 /*the user wants out of this loop*/
y=space(translate(y,$,$||xrange())) /*allow any sep user wants.*/
parse var y a.1 a.2 a.3 a.4 /*parse the pertinent parameters.*/
if a.1=='QUIT' then exit 0 /*the user wants out of this loop*/
if words(y)>4 then do /*did the user have fingeritis ? */
say 'too many parameters entered.'
iterate prompt
end /*go and try again to get parms. */
do k=1 for 4 /*validate parms {positive ints}.*/
if datatype(a.k,'W') & a.k>0 then iterate /*found a bad parm.*/
say 'parameter ' k errTxt a.k /*issue an error message to term.*/
iterate prompt /*go & ask for another set of #s.*/
a.k=a.k/1 /*normalize the user's number. */
end /*k*/ /* [↑] done with the validations*/
parse var y p l w c /*parse parameters for names. */
x=substr(word(@.p.l,w),c,1) /*extract the character from book*/
if x=='!' then leave /*if the stop char found, done.*/
say right(x '◄─── a letter',46) /*might as well echo char to term*/
?=? || x /*append the character to phrase.*/
end /*j*/ /* [↑] go & keep building phrase*/
say '═════►' ? /*display letters found from book*/
/*stick a fork in it, we're done.*/</lang>
'''input''' &nbsp; supplied to the console (terminal) by the user &nbsp; (the commas are optional):
<pre>
1, 133, 4, 5
1, 34, 9, 3
1, 1377, 2, 2
1, 4, 8, 4
1, 265, 3, 5
1, 413, 10, 2
1, 10, 12, 1
1, 144, 10, 10
1, 571, 4, 12
</pre>
'''output''' &nbsp; (abbridged)
<pre>
──────────enter four parameters (all positive integers) or QUIT
1, 133, 4, 5
s ◄─── a letter
──────────enter four parameters (all positive integers) or QUIT

·
·
·

═════► so─true.
</pre>
The input file used (the IBM jargon file) in the above REXX program can be found here.
<br>


=={{header|Tcl}}==
=={{header|Tcl}}==
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