Autoformat: Make match result available in format and preFormat functions

[whytspace]

I wanted to implement an autoformat rule that would allow users to start a list at a specific item.

So when the user types 1. , the list would start at one, but if the user typed 16. , the list would start at 16.

I wanted to use a regex for this, so that any number followed by . sets the start attribute. Most of the code is straightforward, although I am struggling to get the replaced number within the format function:

  {
    mode: "block",
    type: ListItemPlugin.key,
    match: [
      // "1. "
      String.raw`^\d+\.$ `,
      // "1) "
      String.raw`^\d+\)$ `,
      // "1.) "
      String.raw`^\d+\.\)$ `,
    ],
    matchByRegex: true,
    preFormat,
    format: (editor) => {
      format(editor, () => {
        toggleList(editor, { type: NumberedListPlugin.key });
        // set attribute "start" based on number inserted
        setNodes(
          editor,
          { attributes: { start: <<INSERT NUMBER HERE>> } },
          {
            match: (n) =>
              isBlock(editor, n) && n.type === NumberedListPlugin.key,
          }
        );
      });
    },
  },

Am I missing something? Is there any way to access the matched value?

I checked https://github.com/udecode/plate/blob/main/packages/autoformat/src/lib/transforms/autoformatBlock.ts#L93 and it seems that the value is already removed from the editor.
Could match be passed as an argument to the format (and mybe even the preFormat) function?

---

The alternative I implemented now is to generate a rule for every single supported number, which I now limited to the numbers 1-99:

const createNumberedListStartRule = (start: number): AutoformatRule => ({
  mode: "block",
  type: ListItemPlugin.key,
  match: [`${start}. `, `${start}) `, `${start}.) `],
  preFormat,
  format: (editor) => {
    format(editor, () => {
      toggleList(editor, { type: NumberedListPlugin.key });
      setNodes(
        editor,
        { attributes: { start } },
        {
          match: (n) => isBlock(editor, n) && n.type === NumberedListPlugin.key,
        }
      );
    });
  },
});

// usage:
rules: [
  ...Array.from({ length: 99 }, (_, i) => i + 1).map(createNumberedListStartRule),
]

[fastindian84]

@whytspace

Faced the same issue, found a workaround you may retrieve just removed text from the operations property. Not sure if it stable enough to use though, but I guess adding a couple of guards could help.

    format: (editor) => {
      const { text = "" } = editor.operations[0]