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[REBOL] Parse refactoring puzzle

From: SunandaDH:aol at: 30-Jul-2003 2:10

I've just written a function which, though it works, annoys me as I'm sure if I knew a bit more about parse, I could do it in one parse rather than a parse in a loop. The problem is we have a string that has some "place-holders" (identified as !!xxx!! where xxx can be anything), eg: {Welcome !!name!! your address is !!street!! !!town!! !!city!! !!state!! !!country!!} Code before ours has made substitutions, but may have left some stray place-holders: {Welcome John-Paul your address is The Vatican !!town!! Roma !!state!! Italia} So I now want to remove the remaining place-holders: {Welcome John-Paul your address is The Vatican Roma Italia} (We don't need to clear the doubled spaces. We'll let the caller do a trim if that's what they want). The function I wrote, and some test data is below. Can anyone suggest a one-parse approach? Thanks! Sunanda. ;; ======================================= clear-place-holders: func [str [string!] /local out-str ph ][ out-str: copy str ;;work on copy so str if unchanged if we fail forever [ ph: none parse/all out-str [thru "!!" copy ph to "!!"] if none? ph [break] replace/all out-str join "!!" [ph "!!"] "" ] return out-str ] print clear-place-holders {no place holders in this string} print clear-place-holders {!!begin!!text!!end!!} print clear-place-holders {text!!middle!! more text} print clear-place-holders {!!bad-holder and some text} print clear-place-holders {!!good!holder, even if a little weird!!and some text} print clear-place-holders {same!!same!!!!same!!!!same!! place-holder!!same!! five!!same!! times} print clear-place-holders {leaves null place-holder !!!! in output, but another function might remove it. Either way is fine} ;; =======================================