Background
I have a dataframe of stock prices and am trying to build a trading entry signal. The logic is to enter position one day after whenever there is a Trigger with a stop loss signal “Exit”

Because once there has been an Entry I will hold the position until stopped out, a new Entry (except the first) can only occur once there has been an Exit after the previous Entry. (e.g. 2 Entries cannot happen without an Exit in between)

Problem
I am having trouble how to create Entry signals in column “signal 3” to uniquely capture only real Entry (Trigger day after if there has been an Exit after the previous Entry).

Below dataframe is what I am working with:

Date         Price  Trigger   signal 3   Stop Loss
2024-03-06  9540.0  NaN          NaN    NaN
2024-03-07  10270.0 NaN          NaN    NaN
2024-03-08  8120.0  Trigger      NaN    NaN
2024-03-11  6620.0  NaN          Entry  NaN
2024-03-12  5620.0  NaN          NaN    NaN
2024-03-13  6620.0  NaN          NaN    Exit
2024-03-14  5930.0  NaN          NaN    NaN
...
2024-03-22  7120.0  Trigger      NaN    NaN
2024-03-28  6090.0  NaN          Entry  NaN
2024-03-29  5680.0  Trigger      NaN    NaN
2024-04-01  5340.0  NaN          NaN    NaN
2024-04-02  4885.0  NaN          NaN    NaN

As per example above the last Trigger should not result in an entry since the Trigger before that lead to an Entry but no Exit was defined.

Right now I am only using a for loop to iterate through every single row with a variable called position that increments to 1 whenever entry is made and resets to 0 when exit is made but given this is a dataframe there must be a vectorized faster solution.