// Some rules have just added to the ignore,
        // making the behavior changed.
        if (this._added) {
            this._initCache()
        }

        return this
    }

    // legacy
    addPattern (pattern) {
        return this.add(pattern)
    }

    //          |           ignored : unignored
    // negative |   0:0   |   0:1   |   1:0   |   1:1