Use zprint to format a range of lines in a file

Usually, zprint is used to format all of the lines in a file.

However, you can format a range of lines in a file using either the command line zprint programs, or when using zprint as a library.

A range specification looks like:

{:input {:range {:start start-line-number :end end-line-number}}}

where start-line-number and end-line-number are zero based, and are inclusive (that is to say, both lines will be formatted).

Since zprint can only format effectively if it knows the left margin, the start-line-number and end-line-number are expanded outwards to encompass one or more top level expressions.

The expression in which the start-line-number is located is determined, and then the start-line-number is moved up to the first line beyond the previous expression. This is in order to encompass any ;!zprint {} directives that might appear directly before the expression. The expression in which the end-line-number is located is determined, and the end-line-number is moved down to the last line of that expression.

Note that any ;!zprint directives that appear before the previous expression will not be recognized when formatting a range of lines.

If any problems occur when trying to determine the current or previous expressions (since a quick parse of the entire file is required for this to happen), the entire file is formatted.