forked from Alepha/Alepha
ADAM David Alan Martin
7410245314
This should help when building custom language parsers. An input stream can be augmented with this stackable streambuf to track the current line number. This can (and should) be done low in the stack, so that any variable expansion and comment stripping stages will not affect line number count. The stage bolts on a stream state sidecar to point back to itself. The observer for the current line peeks into the sidecar to see the current line number tracking object for the stream and then gets the current line number from that object. The line number is the current line the input cursor is on. Newline characters are treated as-if they're part of the current line. The newly created line will start on the first character after the newline character. This helps keep line-index counts accurate too. (Idea for a further stage? Line index cursor too?)