Function countLeaves

src/math-json/utils.ts:474–498

(expr: MathJsonExpression | null)

/** The number of leaves (atomic expressions) in the expression */
export function countLeaves(expr: MathJsonExpression | null): number {
  if (expr === null) return 0;
  if (typeof expr === 'number' || typeof expr === 'string') return 1;
  if (isNumberExpression(expr) || isSymbolObject(expr) || isStringObject(expr))
    return 1;

  if (Array.isArray(expr)) return countFunctionLeaves(expr);
  if ('fn' in expr) return countFunctionLeaves(expr.fn);

  const dict = dictionaryFromExpression(expr);
  if (dict) {
    const dictRecord = dict as unknown as Record<
      string,
      MathJsonExpression | null
    >;
    const keys = Object.keys(dictRecord);
    return (
      1 +
      keys.length +
      keys.reduce<number>((acc, x) => acc + countLeaves(dictRecord[x]), 0)
    );
  }

  return 0;
}

/** True if the string matches the expected pattern for a number */
export function matchesNumber(s: string): boolean {