Returns flag if a given key has a value in cache or not.
@since 1.0
@param string $key Cache key name.
@return bool
170730
public static function has( $key )
	{
		$cache = self::instance();
		if ( $cache ) {
			return $cache->isExisting( $key );
		}
		return false;
	}
860230
public function has($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;
    }
372578
public function has($key)
        {
            if (!$this->enabled) return false;

            switch ($this->type) {
                case self::TYPE_APC:
                    $success = false;
                    apc_fetch($key, $success);
                    break;
                case self::TYPE_FILE:
                    $filename = $this->path . $key . '.cache';
                    $success = file_exists($filename);
                    break;
                case self::TYPE_DUMMY:
                default:
                    $success = false;
            }

            return $success;
        }
1222616
public function containsKey($key): bool
    {
        return isset($this->items[$key]) || array_key_exists($key, $this->items);
    }
1257464
public function hasVal($key) {
        return isset($this->field[$key]) || (is_array($this->field) && array_key_exists($key, $this->field));
    }
1061627
public function isInCache($key)
  {
    $value = $this->memcache->get($this->buildMKey($key));
    if ($value) {
      return true;
    }
    return false;
  }
439755
public function has(string $key): bool
    {
        $key = $this->getKey($key, true);
        return isset($this->headers[$key]);
    }
76220
public function has($key)
	{
		return $this->engine->get($this->id($key)) !== false || $this->engine->getResultCode() != \Memcached::RES_NOTFOUND;
	}
732119
public function has($key)
    {
        $value = $this->get($key);
        if ($value === false) {
            return false;
        }

        return true;
    }
162179
public function has($key): bool
    {
        return isset($this->items[$key]) || array_key_exists($key, $this->items);
    }
720766
public function has($key)
    {
        // For performance, we can use isset,
        // but it will not match if value == 0
        return isset($this->values[$key]) || array_key_exists($key, $this->values);
    }
1339046
public function hasQuery($key)
    {
        $arrayKeys = array_keys($_GET);
        $keys = is_array($key) ? $key : func_get_args();

        foreach ($keys as $value) {
            if (!in_array($value, $arrayKeys) || trim((string)$_GET[$value]) === '') {
                return false;
            }
        }

        return true;
    }
543476
public function has(/*# string */ $key)/*# : int */
    {
        // try front-end cache first
        $res = $this->frontHas($key);
        if ($res) {
            return $res;
        }

        // try backend cache
        return $this->backHas($key);
    }
954623
public function hasValue(string $key): bool
    {
        if (!$this->isValid()) {
            return false;
        }

        return $this->storage->hasValue($key);
    }
203920
public function hasKey(string $key): bool
    {
        if (null === $this->data) {
            $this->buildIndex();
        }

        return $key && strpos($key, '@@') === false && isset($this->data[$key]);
    }
1294830
public function has($key)
    {
        $array = $this->array;

        if (empty($array) || is_null($key)) {
            return false;
        }

        if (array_key_exists($this->unescapeDotKey($key), $array)) {
            return true;
        }

        foreach (explode('.', $this->escapedDotKeyToUnderscore($key)) as $segment) {
            $segment = $this->underscoreDotKeyToDot($segment);

            if (is_array($array) === false || array_key_exists($segment, $array) === false) {
                return false;
            }

            $array = $array[$segment];
        }

        return true;
    }
725764
public function has($key)
    {
        $keys = is_array($key) ? $key : func_get_args();

        foreach ($keys as $value) {
            if (! $this->offsetExists($value)) {
                return false;
            }
        }

        return true;
    }