polygerrit-ui/app/elements/shared/revision-info/revision-info.html

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<link rel="import" href="../../../behaviors/gr-patch-set-behavior/gr-patch-set-behavior.html">
<script>
  (function() {
    'use strict';

    /**
     * @param {Object} change A change object resulting from a change detail
     *     call that includes revision information.
     */
    function RevisionInfo(change) {
      this._change = change;
    }

    /**
     * Get the largest number of parents of the commit in any revision. For
     * example, with normal changes this will always return 1. For merge changes
     * wherein the revisions are merge commits this will return 2 or potentially
     * more.
     *
     * @return {Number}
     */
    RevisionInfo.prototype.getMaxParents = function() {
      if (!this._change || !this._change.revisions) {
        return 0;
      }
      return Object.values(this._change.revisions)
          .reduce((acc, rev) => Math.max(rev.commit.parents.length, acc), 0);
    };

    /**
     * Get an object that maps revision numbers to the number of parents of the
     * commit of that revision.
     *
     * @return {!Object}
     */
    RevisionInfo.prototype.getParentCountMap = function() {
      const result = {};
      if (!this._change || !this._change.revisions) {
        return {};
      }
      Object.values(this._change.revisions)
          .forEach(rev => { result[rev._number] = rev.commit.parents.length; });
      return result;
    };

    /**
     * @param {number|string} patchNum
     * @return {number}
     */
    RevisionInfo.prototype.getParentCount = function(patchNum) {
      return this.getParentCountMap()[patchNum];
    };

    /**
     * Get the commit ID of the (0-offset) indexed parent in the given revision
     * number.
     *
     * @param {number|string} patchNum
     * @param {number} parentIndex (0-offset)
     * @return {string}
     */
    RevisionInfo.prototype.getParentId = function(patchNum, parentIndex) {
      const rev = Object.values(this._change.revisions).find(rev =>
        Gerrit.PatchSetBehavior.patchNumEquals(rev._number, patchNum));
      return rev.commit.parents[parentIndex].commit;
    };

    window.Gerrit = window.Gerrit || {};
    window.Gerrit.RevisionInfo = RevisionInfo;
  })();
</script>