hyparquet/src/utils.js

/**
 * Replace bigints with numbers.
 * When parsing parquet files, bigints are used to represent 64-bit integers.
 * However, JSON does not support bigints, so it's helpful to convert to numbers.
 *
 * @param {any} obj object to convert
 * @returns {unknown} converted object
 */
export function toJson(obj) {
  if (obj === undefined) return null
  if (typeof obj === 'bigint') return Number(obj)
  if (Array.isArray(obj)) return obj.map(toJson)
  if (obj instanceof Uint8Array) return Array.from(obj)
  if (obj instanceof Date) return obj.toISOString()
  if (obj instanceof Object) {
    /** @type {Record<string, unknown>} */
    const newObj = {}
    for (const key of Object.keys(obj)) {
      if (obj[key] === undefined) continue
      newObj[key] = toJson(obj[key])
    }
    return newObj
  }
  return obj
}

/**
 * Concatenate two arrays fast.
 *
 * @typedef {import('./types.js').DecodedArray} DecodedArray
 * @param {any[]} aaa first array
 * @param {DecodedArray} bbb second array
 */
export function concat(aaa, bbb) {
  const chunk = 10000
  for (let i = 0; i < bbb.length; i += chunk) {
    aaa.push(...bbb.slice(i, i + chunk))
  }
}