constructor(layout, direction, axis, dev = false) {
    this.layout = layout;
    this.horizontal = axis === "horizontal" ? true : false;
    this.direction = direction || "ltr";
    this._dev = dev;
  }
Map text locations to CFI ranges
@class
@param {Layout} layout Layout to apply
@param {string} [direction="ltr"] Text direction
@param {string} [axis="horizontal"] vertical or horizontal axis
@param {boolean} [dev] toggle developer highlighting