@loaders.gl/schema/src/lib/table/simple-table/data-type.ts

Table format APIs for JSON, CSV, etc...

// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import {DataType} from '../../../types/schema';
import {TypedArray, TypedArrayConstructor, ArrayType} from '../../../types/types';

/** Deduce column types from values */
export function getDataTypeFromValue(
  value: unknown,
  defaultNumberType: 'float32' = 'float32'
): DataType {
  if (value instanceof Date) {
    return 'date-millisecond';
  }
  if (value instanceof Number) {
    return defaultNumberType;
  }
  if (typeof value === 'string') {
    return 'utf8';
  }
  if (value === null || value === 'undefined') {
    return 'null';
  }
  return 'null';
}

/**
 * Deduces a simple data type "descriptor from a typed array instance
 */
export function getDataTypeFromArray(array: ArrayType): {type: DataType; nullable: boolean} {
  let type = getDataTypeFromTypedArray(array as TypedArray);
  if (type !== 'null') {
    return {type, nullable: false};
  }
  if (array.length > 0) {
    type = getDataTypeFromValue(array[0]);
    return {type, nullable: true};
  }

  return {type: 'null', nullable: true};
}

/**
 * Deduces a simple data type "descriptor from a typed array instance
 */
export function getDataTypeFromTypedArray(array: TypedArray): DataType {
  switch (array.constructor) {
    case Int8Array:
      return 'int8';
    case Uint8Array:
    case Uint8ClampedArray:
      return 'uint8';
    case Int16Array:
      return 'int16';
    case Uint16Array:
      return 'uint16';
    case Int32Array:
      return 'int32';
    case Uint32Array:
      return 'uint32';
    case Float32Array:
      return 'float32';
    case Float64Array:
      return 'float64';
    default:
      return 'null';
  }
}

export function getArrayTypeFromDataType(
  type: DataType,
  nullable: boolean | undefined
): TypedArrayConstructor | ArrayConstructor {
  if (!nullable) {
    switch (type) {
      case 'int8':
        return Int8Array;
      case 'uint8':
        return Uint8Array;
      case 'int16':
        return Int16Array;
      case 'uint16':
        return Uint16Array;
      case 'int32':
        return Int32Array;
      case 'uint32':
        return Uint32Array;
      case 'float32':
        return Float32Array;
      case 'float64':
        return Float64Array;
      default:
        break;
    }
  }

  // if (typeof BigInt64Array !== 'undefined') {
  //   TYPED_ARRAY_TO_TYPE.BigInt64Array = new Int64();
  //   TYPED_ARRAY_TO_TYPE.BigUint64Array = new Uint64();
  // }

  return Array;
}