Check if key exist.

@param string $key Uses dot notation.
@return bool
433328
public function has(string $key): bool
    {
        $key = $this->prepareKey($key);
        return Arr::has($this->properties, $key);
    }
266238
public function exists(?string $key = null) : bool
    {
        $key = $this->constructKey($key);

        return $this->parseKey($key, function ($part, $result) {
            return array_key_exists($part, $result);
        });
    }
1272101
public function exists( $key ) {
		return ( is_array( $this->data ) && array_key_exists( $key, $this->data ) ) ||
			( is_object( $this->data ) && property_exists( $this->data, $key ) );
	}
439755
public function has(string $key): bool
    {
        $key = $this->getKey($key, true);
        return isset($this->headers[$key]);
    }
203920
public function hasKey(string $key): bool
    {
        if (null === $this->data) {
            $this->buildIndex();
        }

        return $key && strpos($key, '@@') === false && isset($this->data[$key]);
    }
578242
public function exists($key) {

		if(false === is_string($key) && false === is_array($key)) {
   			return trigger_error(sprintf('Argument 1 passed to %s() must be of the type string or array, "%s" given', __METHOD__, gettype($key)), E_USER_ERROR);
   		}

   		if(0 === strlen($key)) {
   			return trigger_error(sprintf('Argument 1 passed to %s() may not be an empty string', __METHOD__), E_USER_ERROR);
   		}

		return apcu_exists($key);
	}
759919
protected function exists($key)
    {
        if (!array_key_exists($key, $this->items)) {
            // key not in cache
            return false;
        }

        $expire = $this->items[$key][1];
        if ($expire !== 0 && $expire < time()) {
            // not permanent & already expired
            $this->size -= strlen($this->items[$key][0]);
            unset($this->items[$key]);

            return false;
        }

        $this->lru($key);

        return true;
    }
1105983
public function has(string $key) : bool
    {
        return isset($this->collection[$this->useKey($key)]);
    }
619011
private static function keyExists($key)
    {
        $apiKeyCount = self::where('key', '=', $key)->limit(1)->count();

        if ($apiKeyCount > 0) return true;

        return false;
    }
860230
public function has($key)
    {
        if (is_null($key)) {
            return $this->any();
        }

        $keys = is_array($key) ? $key : func_get_args();

        foreach ($keys as $key) {
            if ($this->first($key) === '') {
                return false;
            }
        }

        return true;
    }
590745
public function exists($key)
    {
        if ($this->enabled) {
            return !$this->pool->getItem($key)->isMiss();
        } else {
            return false;
        }
    }
242177
public function do_exists($key)
    {
        $redis = is_object($this->_redis) ? $this->_redis : $this->_getRedis();
        return (bool)$redis->exists($this->_prefix . $key);
    }
1207867
public function has(string $key): bool
    {
        $this->assertRead();

        return \array_key_exists($key, $this->data);
    }
220977
public function containsKey($key)
    {
        if (!$this->enabled)
            return false;

        $has_key = array_key_exists($this->key($key), $this->cache);

        // $this->Logger->debug("Cache contains {$key}? " . (($has_key) ? 'TRUE' : 'FALSE'));

        return $has_key;
    }
346821
public static function has(string $key) : bool
  {
    $expect = explode('.', $key);
    $config = Config::all();

    foreach($expect as $setting) {
      if (!isset($config[$setting])) return false;
      $config = $config[$setting];
    }

    return true;
  }
417126
public function has($key)
    {
        $keys = explode('.', (string)$key);
        $data = &$this->data;
        foreach ($keys as $key) {
            if (!isset($data[$key])) {
                return false;
            }
            $data = &$data[$key];
        }

        return true;
    }
288391
public function has(string $key){
        $data   = $this->status() === self::ACTIVE
            ? $_SESSION : $this->finishedData;
        
        return array_key_exists($key, $data);
    }