Here's another solution, somewhat more elegant than my previous one. 
s{<code>(.+?)</ code>|\[(.+?)\]|(<!--.+?-->)}
 {defined $1 ? "$GREEN$1$RESET" :
  defined $2 ? "$RED$2$RESET"   :
  defined $3 ? "$YELLOW$3$RESET"
  : warn "Broken with $+\n"
 }ge;

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In reply to Re: Substitute for variable-length look-behind? by Roy Johnson
in thread Substitute for variable-length look-behind? by diotalevi

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