SU-SWS/decanter

/// Converts a string to number.
///
/// String to number converter.
/// Returns a number value.
///
/// @name to-number
///
/// @param {String} $value - Value to be parsed
///
/// @group mixin
@function to-number($value) {
  @if type-of($value) == 'number' {
    @return $value;
  } @else if type-of($value) != 'string' {
    @error 'Value for `to-number` should be a number or a string.';
  }

  $result: 0;
  $digits: 0;
  $minus: str-slice($value, 1, 1) == '-';
  $numbers: ('0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9);

  @for $i from if($minus, 2, 1) through str-length($value) {
    $character: str-slice($value, $i, $i);

    @if not (index(map-keys($numbers), $character) or $character == '.') {
      @return to-length(
        if($minus, -$result, $result), str-slice($value, $i)
      );
    }

    @if $character == '.' {
      $digits: 1;
    }
    @else if $digits == 0 {
      $result: $result * 10 + map-get($numbers, $character);
    }
    @else {
      $digits: $digits * 10;
      $result: $result + map-get($numbers, $character) / $digits;
    }
  }

  @return if($minus, -$result, $result);
}