diff_tree.py 文件源码

def _find_exact_renames(self):
        add_map = defaultdict(list)
        for add in self._adds:
            add_map[add.new.sha].append(add.new)
        delete_map = defaultdict(list)
        for delete in self._deletes:
            # Keep track of whether the delete was actually marked as a delete.
            # If not, it needs to be marked as a copy.
            is_delete = delete.type == CHANGE_DELETE
            delete_map[delete.old.sha].append((delete.old, is_delete))

        add_paths = set()
        delete_paths = set()
        for sha, sha_deletes in delete_map.items():
            sha_adds = add_map[sha]
            for (old, is_delete), new in zip(sha_deletes, sha_adds):
                if stat.S_IFMT(old.mode) != stat.S_IFMT(new.mode):
                    continue
                if is_delete:
                    delete_paths.add(old.path)
                add_paths.add(new.path)
                new_type = is_delete and CHANGE_RENAME or CHANGE_COPY
                self._changes.append(TreeChange(new_type, old, new))

            num_extra_adds = len(sha_adds) - len(sha_deletes)
            # TODO(dborowitz): Less arbitrary way of dealing with extra copies.
            old = sha_deletes[0][0]
            if num_extra_adds > 0:
                for new in sha_adds[-num_extra_adds:]:
                    add_paths.add(new.path)
                    self._changes.append(TreeChange(CHANGE_COPY, old, new))
        self._prune(add_paths, delete_paths)