%PDF-
%PDF-
Mini Shell
Mini Shell
<?php
namespace TeamTNT\TNTSearch\Support;
class Expression
{
protected $operatorQueue;
protected $tokenQueue;
public function toPostfix($exp)
{
$postfix = [];
$stack = [];
$tokens = $this->lex($exp);
foreach ($tokens as $token) {
if ($this->isOperand($token)) {
$postfix[] = $token;
} else {
if ($token == ")") {
while (($top = array_pop($stack)) != "(") {
$postfix[] = $top;
}
} else {
while (
count($stack) && !(end($stack) == "(") &&
($this->priority(end($stack)) >= $this->priority($token))
) {
$postfix[] = array_pop($stack);
}
$stack[] = $token;
}
}
}
while (!empty($stack)) {
$postfix[] = array_pop($stack);
}
return $postfix;
}
public function isOperand($str)
{
if (
($str == "|") || ($str == "&") || ($str == "~") ||
($str == "(") || ($str == ")")
) {
return false;
}
return true;
}
public function isOperator($str)
{
return !$this->isOperand($str);
}
public function priority($operator)
{
$priority = 0;
if ($operator == ("&")) {
$priority = 2;
}
if ($operator == "~") {
$priority = 3;
}
if ($operator == "|") {
$priority = 1;
}
if ($operator == "(" || $operator == ")") {
$priority = 4;
}
return $priority;
}
public function lex($string)
{
$bad = [' or ', ' -', ' '];
$good = ['|', '~', '&'];
$string = str_replace($bad, $good, $string);
$string = mb_strtolower($string);
$tokens = [];
$token = "";
foreach (str_split($string) as $char) {
if ($this->isOperator($char)) {
if ($token) {
$tokens[] = $token;
}
$tokens[] = $char;
$token = "";
} else {
$token .= $char;
}
}
if ($token) {
$tokens[] = $token;
}
return $tokens;
}
}
Zerion Mini Shell 1.0