Instructions for migrating a mode from CM5->CM6?

v6
11

Got it!
Leaving this here in case anyone else comes looking for a contained example:

import {
  HighlightStyle,
  LanguageSupport,
  StreamLanguage,
  syntaxHighlighting,
} from "@codemirror/language";
import { simpleMode } from "@codemirror/legacy-modes/mode/simple-mode";
import { Tag } from "@lezer/highlight";

const chordBases = ["A", "B", "C", "D", "E", "F", "G"];
const chordStartMatches = chordBases.map(chord => ({
  regex: new RegExp(`\\[${chord}`, "i"),
  push: chord,
  token: `chord-${chord}`,
}));
let chordStates = {};
chordBases.forEach(chord => {
  chordStates[chord] = [
    { regex: /\]/, pop: true, token: `chord-${chord}` },
    { regex: /[^\]]+/, token: `chord-${chord}` },
  ];
});

const chordProSimpleMode = simpleMode({
  start: [
    ...chordStartMatches,
    { regex: /\[/, push: "chord", token: "propertyName" },
    { regex: /\{/, push: "directive", token: "comment" },
  ],
  chord: [
    { regex: /\]/, pop: true, token: "propertyName" },
    { regex: /\w+/, token: "propertyName" },
  ],
  ...chordStates,
  directive: [
    { regex: /\}/, pop: true, token: "comment" },
    { regex: /[\w\s:]+/, token: "comment" },
  ],
  languageData: {
    name: "chordPro",
  },
});

/* @ts-ignore */
chordProSimpleMode.tokenTable = {};
chordBases.forEach(chord => {
  chordProSimpleMode.tokenTable[`chord-${chord}`] = Tag.define();
});

const chordProModeLanguage = StreamLanguage.define(chordProSimpleMode);

export const chordProHighlighter = syntaxHighlighting(
  HighlightStyle.define(
    chordBases.map(chord => ({
      tag: chordProSimpleMode.tokenTable[`chord-${chord}`],
      class: `cm-chord-${chord}`,
    })),
  ),
);

const chordProMode = new LanguageSupport(chordProModeLanguage, [
  chordProHighlighter,
]);
export default chordProMode;