| Server IP : 85.214.239.14 / Your IP : 13.59.36.4 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 : /usr/share/doc/libparse-recdescent-perl/examples/ |
Upload File : |
#!/usr/bin/perl -w
use Parse::RecDescent;
$text = "1 + 2 * 3 ** 4";
$grammar = q{
<autotree>
expr : <leftop: conj /\|\|/ conj>
conj : <leftop: addn /&&/ addn>
addn : <leftop: mult /[+-]/ mult >
mult : <leftop: expo /[*\/\%]/ expo >
expo : <leftop: value /\^|\*\*/ value >
value : /\d+(\.\d+)?/
};
my $extract_tree = Parse::RecDescent->new($grammar);
my $tree = $extract_tree->expr($text);
use Data::Dumper 'Dumper';
print Dumper $tree;
print $tree->eval();
package expr;
use List::Util 'reduce';
sub eval { reduce {$_[0] || $_[1]} map $_->eval(), @{$_[0]{__DIRECTIVE1__}} }
package conj ;
use List::Util 'reduce';
sub eval { reduce {$_[0] && $_[1]} map $_->eval(), @{$_[0]{__DIRECTIVE1__}} }
package addn ;
use List::Util 'reduce';
sub eval { reduce {$_[0] + $_[1]} map $_->eval(), @{$_[0]{__DIRECTIVE1__}} }
package mult ;
use List::Util 'reduce';
sub eval { reduce {$_[0] * $_[1]} map $_->eval(), @{$_[0]{__DIRECTIVE1__}} }
package expo ;
use List::Util 'reduce';
sub eval { reduce {$_[0] ** $_[1]} map $_->eval(), @{$_[0]{__DIRECTIVE1__}} }
package value ;
sub eval { return $_[0]{__VALUE__} }