How do you map changes between a CodeMirror component and an array of objects?

[tomelliot]

I have an array of objects that are represented in a CodeMirror component. I'm trying to work out how to map changes in the CodeMirror to the object. I'm using a RangeSet to hold the underlying object. I was expecting I could use RangeSet.map() to apply the changes from the CodeMirror onto the object RangeSet. I'm not seeing that happen.

Is there an example that can help me understand how to handle this use case in a good way?

type Text = { type: "text"; textValue: string };
type Field = {
  type: "field";
  textValue: string;
  field: {
    fieldId: string;
  };
};
export type TextWithField = (Text | Field)[];

class TextOrFieldRange extends RangeValue {
  type: "text" | "field";
  textOrField: Text | Field;
  theRange;
  constructor(
    from: number,
    to: number,
    type: "text" | "field",
    textOrField: Text | Field
  ) {
    super();
    this.type = type;
    this.textOrField = { ...textOrField };
    this.theRange = this.range(from, to);
  }

  eq(other: RangeValue): boolean {
    return (
      other instanceof TextOrFieldRange &&
      this.type === other.type &&
      this.theRange.from === other.theRange.from &&
      this.theRange.to === other.theRange.to
    );
  }
}

const InputWithFields = ({
  textWithFields,
  setTextWithFields,
}: {
  textWithFields: TextWithField;
  setTextWithFields: (textWithFields: TextWithField) => void;
}) => {
  const rangeBuilder = new RangeSetBuilder<TextOrFieldRange>();
  let combinedText = "";
  const fieldRanges: [number, number][] = [];

  textWithFields.forEach((item) => {
    const start = combinedText.length;
    combinedText += item.textValue;
    const end = combinedText.length;
    rangeBuilder.add(
      start,
      end,
      new TextOrFieldRange(start, combinedText.length, item.type, item)
    );
    item.type == "field" && fieldRanges.push([start, end]);
  });
  const combinedRanges = rangeBuilder.finish();

  const handleTextChange = (value: string, viewUpdate: ViewUpdate) => {
    const newRanges = combinedRanges.map(viewUpdate.changes.desc);
    const iterator = newRanges.iter();
    const newTextWithFields: TextWithField = [];
    while (iterator.value !== null) {
      newTextWithFields.push(iterator.value.textOrField);
      iterator.next();
    }
    setTextWithFields(newTextWithFields);
  };

  const highlightRanges = rangeHighlighter(fieldRanges);

  return (
    <CodeMirror
      value={combinedText}
      onChange={handleTextChange}
      theme="none"
      basicSetup={false}
      editable={true}
      extensions={[...extensions, highlightRanges]}
      maxWidth="100%"
      height="100px"
    />
  );
};