PostgreSQL: recursively shift rows in order using modifier

recursive_shift_rows_with_modifier.sql

-- +--------+-------+-------+
-- | init   | mod   | exp   |
-- |--------+-------+-------|
-- | 6      | -1    | 5     |
-- | 5      | 0     | 4     |
-- | 4      | 1     | 6     |
-- | 3      | 0     | 3     |
-- | 2      | -1    | 1     |
-- | 1      | 0     | 2     |
-- +--------+-------+-------+

WITH v(init, mod, exp) AS (
    VALUES (6, -1, 5), (5, 0, 4), (4, 1, 6), (3, 0, 3), (2, -1, 1), (1, 0, 2)
), sort_r(init, pos) AS (
    WITH RECURSIVE t(init, mod, exp, pos, d) AS (
        SELECT *, init, 1 FROM v
    UNION ALL
        SELECT t.init, 
            t.mod - (lag(t.mod) OVER w),
            t.exp, 
            t.pos + t.mod,
            t.d + 1
        FROM t
        WHERE t.mod <> 0
        WINDOW w AS (ORDER BY t.pos DESC ROWS 1 PRECEDING)
    )
    SELECT init, row_number() OVER (ORDER BY pos ASC)
    FROM (SELECT * FROM t WHERE d = (SELECT max(d) FROM t t2 WHERE t2.init = t.init)) sub
)
SELECT sort_r.*, v.exp FROM sort_r, v WHERE v.init = sort_r.init ORDER BY pos DESC;

-- +--------+-------+-------+
-- | init   | pos   | exp   |
-- |--------+-------+-------|
-- | 4      | 6     | 6     |
-- | 6      | 5     | 5     |
-- | 5      | 4     | 4     |
-- | 3      | 3     | 3     |
-- | 1      | 2     | 2     |
-- | 2      | 1     | 1     |
-- +--------+-------+-------+
--
-- \ 0 /