| Server IP : 85.214.239.14 / Your IP : 3.144.1.100 Web Server : Apache/2.4.62 (Debian) System : Linux h2886529.stratoserver.net 4.9.0 #1 SMP Tue Jan 9 19:45:01 MSK 2024 x86_64 User : www-data ( 33) PHP Version : 7.4.18 Disable Function : pcntl_alarm,pcntl_fork,pcntl_waitpid,pcntl_wait,pcntl_wifexited,pcntl_wifstopped,pcntl_wifsignaled,pcntl_wifcontinued,pcntl_wexitstatus,pcntl_wtermsig,pcntl_wstopsig,pcntl_signal,pcntl_signal_get_handler,pcntl_signal_dispatch,pcntl_get_last_error,pcntl_strerror,pcntl_sigprocmask,pcntl_sigwaitinfo,pcntl_sigtimedwait,pcntl_exec,pcntl_getpriority,pcntl_setpriority,pcntl_async_signals,pcntl_unshare, MySQL : OFF | cURL : OFF | WGET : ON | Perl : ON | Python : ON | Sudo : ON | Pkexec : OFF Directory : /proc/2/root/usr/share/doc/libparse-recdescent-perl/examples/ |
Upload File : |
#!/usr/bin/perl -ws
use Parse::RecDescent;
sub evalop
{
my (@list) = @{[@{$_[0]}]};
my $val = shift(@list)->();
while (@list)
{
my ($op, $arg2) = splice @list, 0, 2;
$op->($val,$arg2->());
}
return $val;
}
my $parse = Parse::RecDescent->new(<<'EndGrammar');
main: expr /\s*\Z/ { $item{expr}->() }
| <error: expected expression in $item{__RULE__}>
expr: /for(each)?/ lvar range expr
{ my ($vname,$expr) = @item{"lvar","expr"};
my ($from, $to) = @{$item{range}};
sub { my $val;
no strict "refs";
for $$vname ($from->()..$to->())
{ $val = $expr->() }
return $val;
}
}
| lvar '=' addition
{ my ($vname, $expr) = @item{"lvar","addition"};
sub { no strict 'refs'; $$vname = $expr->() }
}
| addition
range: "(" expr ".." expr ")"
{ [ @item[2,4] ] }
addition: <leftop:multiplication add_op multiplication>
{ my $add = $item[1]; sub { ::evalop $add } }
add_op: '+' { sub { $_[0] += $_[1] } }
| '-' { sub { $_[0] -= $_[1] } }
multiplication: <leftop:factor mult_op factor>
{ my $mult = $item[1]; sub { ::evalop $mult } }
mult_op: '*' { sub { $_[0] *= $_[1] } }
| '/' { sub { $_[0] /= $_[1] } }
factor: number
| rvar
| '(' expr ')' { $item{expr} }
number: /[-+]?\d+(\.\d+)?/ { sub { $item[1] } }
lvar: /\$([a-z]\w*)/ { $1 }
rvar: lvar { sub { no strict 'refs'; ${$item{lvar}} } }
EndGrammar
print "> ";
while (<>) { # FOR DEMO CHANGE TO: while (<DATA>)
print eval {$parse->main($_)}||"", "\n\n> ";
}
__DATA__
$x = 2
$y = 3
+1-1+1-1+1-1+1-1+1
7*7-6*8
121/(121/11)/121*11
1/(10-1/(1/(10-1)))
$x * $y
foreach $i (1..$y) $x = $x * 2 + $i
$x