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:- object(shell).
:- info([
version is 1.0,
date is 2004/4/29,
author is 'Paulo Moura',
comment is 'Simple example of command-line shell parsing.']).
:- public(parse/2).
:- mode(parse(@list, -list), zero_or_one).
:- info(parse/2, [
comment is 'Parses a sequence of commands.',
argnames is ['Sequence', 'Commands']]).
parse(Sequence, Commands) :-
phrase(commands(Commands), Sequence).
commands([C| Cs]) -->
command(C), separator, commands(Cs).
commands([C]) -->
command(C).
separator --> ";".
whitespace --> " ", whitespace.
whitespace --> [].
command(Cd) -->
whitespace, "cd", whitespace, cdargs(Args), whitespace,
{atom_concat(cd, Args, Cd)}.
command(Ls) -->
whitespace, "ls", whitespace, lsargs(Args), whitespace,
{atom_concat(ls, Args, Ls)}.
command(pwd) -->
whitespace, "pwd", whitespace.
cdargs(' ~') --> "~".
cdargs(' ..') --> "..".
cdargs(' .') --> ".".
cdargs('') --> [].
lsargs(' -l') --> "-l".
lsargs(' -a') --> "-a".
lsargs('') --> [].
:- end_object.
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