BEGIN { 

  split("c: ::ab+", fs_arr, ":") 

}

{

  for (i = 1; i in fs_arr; ++i) {

    split($0, a, fs_arr[i], seps)

    print zipcat(a, seps)

    dump_array(seps)

  }

}

END { 

  seps[1] = "123"; seps[5] = 10

  for (i = 1; i in fs_arr; ++i) {

    split("", a, fs_arr[i], seps)

    dump_array(seps)

  }

}

function dump_array(a,   i, mini, maxi)

{

  mini = minidx(a) + 0

  maxi = maxidx(a) + 0

  printf "{"

  for (i = mini; i <= maxi; ++i)

    if (i in a) {

      if (i > mini)

        printf ", "

      printf "%d => \"%s\"", i, a[i]

    }

  printf "}\n"

}

function zipcat(a, b,   c)

{

  zip(a, b, c)

  return cat(c)

}

function cat(a,   mini, maxi, i, s)

{

  mini = minidx(a) + 0

  maxi = maxidx(a) + 0

  for (i = mini; i <= maxi; ++i)

    if (i in a)

      s = s a[i]

  return s

}

function zip(a, b, c,   mini, maxi, i)

{

  del(c)

  mini = minidx2(a, b) + 0

  maxi = maxidx2(a, b) + 0

  for (i = mini; i <= maxi; ++i) {

    if (i in a)

      c[i] = a[i]

    if (i in b)

      c[i] = c[i] b[i]

  }

}

function maxidx2(a, b)

{

  if (emptyarr(a))

    return maxidx(b)

  else if (emptyarr(b))

    return maxidx(a)

  else

    return max(maxidx(a), maxidx(b))

}

function minidx2(a, b)

{

  if (emptyarr(a))

    return minidx(b)

  else if (emptyarr(b))

    return minidx(a)

  else

    return min(minidx(a), minidx(b))

}

function maxidx(a,   i, m)

{

  if (emptyarr(a))

    m = ""

  else {

    m = choose(a) + 0

    for (i in a) {

      i += 0

      if (i > m)

        m = i

    }

  }

  return m

}

function minidx(a,   i, m)

{

  if (emptyarr(a))

    m = ""

  else {

    m = choose(a) + 0

    for (i in a) {

      i += 0

      if (i < m)

        m = i

    }

  }

  return m

}

function choose(a,   m)

{

  for (m in a)

    return m

  return ""

}

function emptyarr(a,  k)

{

  for (k in a)

    return 0

  return 1

}

# portable delete

function del(a)

{

  split("", a)

}

function max(x, y)

{

  return x > y ? x : y

}

function min(x, y)

{

  return x < y ? x : y

}