oxc/website/playground/editor.ts

import type { TreeCursor } from "@lezer/common";
import type { EditorView } from "codemirror";

/**
 * Go down and find the `start` and `end` keys
 */ 
export function getStartAndEnd(
  view: EditorView,
  cursor: TreeCursor
): [start: number | undefined, end: number | undefined] {
  let start: number | undefined, end: number | undefined;
  while (true) {
    if (
      !start &&
      this.getTextFromView(view, cursor.from, cursor.to) == '"start"'
    ) {
      cursor.next();
      start = this.getTextFromView(view, cursor.from, cursor.to);
    }
    if (
      !end &&
      this.getTextFromView(view, cursor.from, cursor.to) == '"end"'
    ) {
      cursor.next();
      end = this.getTextFromView(view, cursor.from, cursor.to);
    }
    if (start && end) {
      break;
    }
    if (!cursor.next()) {
      break;
    }
  }

  return [start, end]
}

export const convertToUtf8 = (sourceTextUtf8: ArrayBuffer, d: number) => {
  return new TextDecoder().decode(sourceTextUtf8.slice(0, d)).length;
}