f64-to-u128.ts

import { u128 } from 'near-sdk-as';

/**
 * Hack to expand f64 vales represented with exponent to a string
 * that can be parsed via u128.fromString(value) e.g.:
 * - 1.0e+23 is expanded to 100000000000000000000000
 * - 2.5e+23 is expanded to 250000000000000000000000
 */
function parseF64ValueToString(value: f64): string {
  const repr = value.toString();
  if (repr.indexOf('e+') < 0) {
    return repr;
  }


  const elements = repr.split('e+');
  const val = elements[0];

  const args = [
    val.charAt(0)
  ];

  let stop = val.indexOf('0') > 0
    ? val.indexOf('0')
    : val.length;

  for (let i = 2; i < stop; i++) {
    args.push(val.charAt(i));
  }

  const exp = parseInt(elements[1]) as i32;
  stop = exp - (args.length - 1);
  for (let i = 0; i < stop; i++) {
    args.push('0');
  }

  return args.join('');
}

export function small_values_ok():u128[] {
  return [
    u128.fromF64(parseFloat('10') as f64),
    u128.fromF64(parseFloat('100') as f64),
    u128.fromF64(parseFloat('1000') as f64),
    u128.fromF64(parseFloat('10000') as f64),
    u128.fromF64(parseFloat('100000') as f64),
    u128.fromF64(parseFloat('10000000') as f64)
  ]
}

export function large_values_from_f64_fails_with_error(): u128[] {
  return [
    u128.fromF64(
      parseFloat('1000000000000000000000000') as f64
    )
  ]
}

export function large_values_from_f64_string_to_wrong_values(): u128[] {
  return [
    u128.fromString(
      (parseFloat('1000000000000000000000000') as f64).toString()
    ),
    u128.fromString(
      (parseFloat('2500000000000000000000000') as f64).toString()
    )
  ]
}

export function large_values_ok(): u128[] {
  return [
    u128.fromString(
      parseF64ValueToString(
        parseFloat('1000000000000000000000000') as f64
      )
    ),
    u128.fromString(
      parseF64ValueToString(
        parseFloat('2500000000000000000000000') as f64
      )
    )
  ]
}


export function large_values_repr():string[] {
  return [
    (parseFloat('1000000000000000000000000') as f64).toString(),
    (parseFloat('2500000000000000000000000') as f64).toString()
  ]
}

export function large_values_repr_parsed():string[] {
  return [
    parseF64ValueToString(
      parseFloat('1000000000000000000000000') as f64
    ),
    parseF64ValueToString(
      parseFloat('2500000000000000000000000') as f64
    )
  ]
}