Line Filter Converter

Parses and verifies user-entered line filtering criteria.

Remarks

Line numbers may be entered as a comma-separated list of positive or negative numbers. A positive number indicates a 1-based line number starting at the beginning of the document. A negative number indicates a 1-based line number starting at the end of the document and counting backwards.
For example, -1 indicates the last line, -2 represents the second-to-last line, and so on.

Below are various examples of the way line filters can be specified. These examples assume a document containing 10 lines of text.

Property Value	Description
1	The first line.
1 to 5	The first 5 lines.
-1	The last line.
-5 to -1	The last 5 lines.
1 to 2, -2 to -1	The first two lines and the last 2 lines.
1, -1	The first and last lines.
1, 2, 4	Lines 1, 2, and 4.
1, 2, -1	Lines 1 and 2, plus the last line.
1, 4 to 6	Lines 1, 4, 5, and 6.
1 to -2	All but the last line of the document.