Code Civ. Proc., § 631.8

(a) After a party has completed his presentation of evidence in a trial by the court, the other party, without waiving his right to offer evidence in support of his defense or in rebuttal in the event the motion is not granted, may move for a judgment. The court as trier of the facts shall weigh the evidence and may render a judgment in favor of the moving party, in which case the court shall make a statement of decision as provided in Sections 632 and 634, or may decline to render any judgment until the close of all the evidence. The court may consider all evidence received, provided, however, that the party against whom the motion for judgment has been made shall have had an opportunity to present additional evidence to rebut evidence received during the presentation of evidence deemed by the presenting party to have been adverse to him, and to rehabilitate the testimony of a witness whose credibility has been attacked by the moving party. Such motion may also be made and granted as to any cross-complaint.

(b) If it appears that the evidence presented supports the granting of the motion as to some but not all the issues involved in the action, the court shall grant the motion as to those issues and the action shall proceed as to the issues remaining. Despite the granting of such a motion, no final judgment shall be entered prior to the termination of the action, but the final judgment in such action shall, in addition to any matters determined in the trial, award judgment as determined by the motion herein provided for.

(c) If the motion is granted, unless the court in its order for judgment otherwise specifies, such judgment operates as an adjudication upon the merits.