<?php
/**
* Class wfBinaryList implements an interface to interact with binary lists. These are internally a sorted list of
* values of a specific size. The sorted aspect allows for very quick searching.
*/
class wfBinaryList {
private $size = 0;
private $list = '';
public function __construct($binary) {
$this->size = ord(wfWAFUtils::substr($binary, 0, 1));
$this->list = wfWAFUtils::substr($binary, 1);
}
public function contains($value) {
if ($this->size == 0) { return false; }
$length = wfWAFUtils::strlen($this->list);
if ($length == 0) { return false; }
$p = wfWAFUtils::substr($value, 0, $this->size);
$count = ceil($length / $this->size);
$low = 0;
$high = $count - 1;
while ($low <= $high) {
$mid = (int) (($high + $low) / 2);
$val = wfWAFUtils::substr($this->list, $mid * $this->size, $this->size);
$cmp = strcmp($val, $p);
if ($cmp < 0) {
$low = $mid + 1;
}
else if ($cmp > 0) {
$high = $mid - 1;
}
else {
return $mid;
}
}
return false;
}
}
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