BNF command line parser

[sylvainhalle]

Existing command line parsers (including Bullwinkle's CliParser) offer a restricted way of defining command line arguments: either -parameter or -parameter value.

Create a new parser where arguments are defined with a BNF grammar. Parsing a command line produces a parse tree that the user can then traverse.

Example:

<S>     := <param> <S> | <param> ;
<param> := <p1> | <p2> ;
<p1>    := -p <args1> ;
<args1> := <num> <num> | zig <num>;
<p2>    := ^foo(bar|baz)$;
<num>   := ^\d+$;

Valid calls would be, for example:

• -p 123 45
• foobaz
• foobar -p zig 2
• -p 1 2 foobar -p zig 34