parsing_rule.bnf

grammar bnf;

start           : and_or;
and_or          : pipe_sequence | and_or AND pipe_sequence | and_or OR pipe_sequence;
pipe_sequence   : command | pipe_sequence PIPE command;
command         : simple_command | subshell | subshell redirect_list;
subshell        : L_PAREN and_or R_PAREN;
simple_command  : cmd_prefix cmd_word cmd_suffix | cmd_prefix cmd_word | cmd_prefix | cmd_name cmd_suffix | cmd_name;
cmd_name        : WORD;
cmd_word        : WORD;
cmd_prefix      : io_redirect | cmd_prefix io_redirect | ASSIGNMENT_WORD | cmd_prefix ASSIGNMENT_WORD;
cmd_suffix      : io_redirect | cmd_suffix io_redirect | WORD | cmd_suffix WORD;
redirect_list   : io_redirect | redirect_list io_redirect;
io_redirect     : io_file | io_here;
io_file         : RED_OUT filename | RED_IN filename | APPEND filename;
filename        : WORD;
io_here         : HERE_DOC here_end;
here_end        : WORD;

PIPE             : '|';
AND              : '&&';
OR               : '||';
L_PAREN          : '(';
R_PAREN          : ')';
WORD             : 'abc';
ASSIGNMENT_WORD  : '=';
RED_OUT          : '>';
RED_IN           : '<';
APPEND           : '>>';
HERE_DOC         : '<<';