import { CommitInfo } from './types';
export declare type MergeCommitsFn = (baseRef: string | undefined, leftRef: string, rightRef: string, depth: number) => string;
export declare type SortRefsFn = (refA: string, refB: string) => number;
export declare type GetCommitFn<N extends CommitInfo> = (ref: string) => N;
/**
 * This function walks up the tree starting at the commits in a breadth-first manner, merging commits,
 * prioritizing lowest refs first, as common ancestors are found.
 *
 * Those merged commits then continue to be merged together until there is just one head commit left.
 *
 * If there are completely un-connected commits, these will be merged with base === undefined
 */
export declare function mergeHeads<N extends CommitInfo>(headRefs: string[], sortRefs: SortRefsFn, getCommit: GetCommitFn<N>, merge: MergeCommitsFn): string | undefined;