formulasUpdated listener

[BrianHung]

#845 #135 handsontable/handsontable#8114

It would be useful to have a formulasUpdated listener, as mentioned in #135.

I've been trying to integrate hyperformula with an external data source (to work with React etc), and have noticed that some methods like addRow and moveRows modify internal formula representations.

Essentially the same problem that handsontable faces in handsontable/handsontable#8114, where you can move rows and columns but formulas referencing values in those moved rows or columns are now out of date.

For example if we had a =SUM(A1:B3) and the third row was deleted, the formula would be changed to =SUM(A1:B2).

Right now the only way to correctly react to changes in formulas is to use getAllSheetsSerialized.

However, this isn't as efficient as valuesUpdated is for listening to changes in values, since there can be a lot of sheets and would cause excessive re-rendering without manual diffs (which is also expensive).

---

For fun, you can try applying https://features.jsomers.net/how-i-reverse-engineered-google-docs/ to google sheets, and can see that they update formulas on things like moveRow too!

[
    [
        24502104,
        "[\"0\",10,1,0,0]" // move 1 row to row 10
    ],
    [
        25813757,
        "[[\"0\",1,2,1,2],[null,null,[[[[[0,10,1,2,1118464],3]]]]],null,[[null,8,null,null,0]]]" // update =SUM(C2:C7) at [rowStart 1, rowEnd 2, colStart 1, colEnd 2] to be =SUM(C2:C10)
    ],
    [
        24549788,
        "[\"0\",\"0\",[[[6,7,10]]],[[[null,null,0]]]]" // move rows in [6, 7) to rowStart 10 
    ],
    [
        21299578,
        "[[\"0\",10,11,0,26],[48630543],[]]" // rowStart 10, rowEnd 11, colStart A, colEnd Z
    ],
    [
        21299578,
        "[[\"0\",6,7,0,26],[1206345535],[]]" // rowStart 6, rowEnd 7, colStart A, colEnd Z
    ],
    [
        25037233,
        "[\"0\",6,1,0]" // move 1 row from row 6
    ],
    [
        21299578,
        "[[\"0\",1,2,1,2],[null,8,null,null,0],[null,null,[[[[[0,9,1,2,1118464],3]]]]]]"
    ]
]

[AMBudnik]

@BrianHung Can I ask you to share the feedback at #1156? I wouldn't want to loose as it is harder to track updates to GitHub Discussions.

[BrianHung]

Done!

[AMBudnik]

Thanks