fix(rxNum/rxInt/rxDouble): Delegate all non mutable operations to the original objects

@@ -3,6 +3,8 @@ import 'dart:collection';
 
 import '../rx_core/rx_interface.dart';
 
+part 'rx_num.dart';
+
 /// global object that registers against `GetX` and `Obx`, and allows the
 /// reactivity
 /// of those `Widgets` and Rx values.
@@ -15,22 +17,6 @@ class _RxImpl<T> implements RxInterface<T> {
 
   T _value;
 
-  /// Common to all Types [T], this operator overloading is using for
-  /// assignment, same as rx.value
-  ///
-  /// Example:
-  /// ```
-  /// var counter = 0.obs ;
-  /// counter <<= 3; // same as counter.value=3;
-  /// print(counter); // calls .toString() now
-  /// ```
-  ///
-  /// WARNING: still WIP, needs testing!
-  _RxImpl<T> operator <<(T val) {
-    subject.add(_value = val);
-    return this;
-  }
-
   bool get canUpdate => _subscriptions.isNotEmpty;
 
   /// Makes this Rx looks like a function so you can update a new
@@ -217,68 +203,6 @@ class RxBool extends _RxImpl<bool> {
   }
 }
 
-/// Rx class for `num` Types (`double` and `int`) shared comparison operations
-abstract class _RxNumComparators<T extends num> extends _RxImpl<T> {
-  bool operator <=(T other) => _value <= other;
-
-  bool operator >=(T other) => _value >= other;
-
-  bool operator <(T other) => _value < other;
-
-  bool operator >(T other) => _value > other;
-}
-
-/// Rx class for `double` Type.
-class RxDouble extends _RxNumComparators<double> {
-  RxDouble([double initial]) {
-    _value = initial;
-  }
-
-  double operator *(double val) => _value * val;
-
-  double operator -(double val) => _value - val;
-
-  double operator +(double val) => _value + val;
-
-  double operator /(double val) => _value / val;
-
-  double operator %(double val) => _value % val;
-}
-
-/// Rx class for `num` Type.
-class RxNum extends _RxNumComparators<num> {
-  RxNum([num initial]) {
-    _value = initial;
-  }
-
-  num operator *(num val) => _value * val;
-
-  num operator -(num val) => _value - val;
-
-  num operator +(num val) => _value + val;
-
-  num operator /(num val) => _value / val;
-
-  num operator %(num val) => _value % val;
-}
-
-/// Rx class for `int` Type.
-class RxInt extends _RxNumComparators<int> {
-  RxInt([int initial]) {
-    _value = initial;
-  }
-
-  int operator %(int val) => _value % val;
-
-  int operator *(int val) => _value * val;
-
-  int operator -(int val) => _value - val;
-
-  int operator +(int val) => _value + val;
-
-  double operator /(int val) => _value / val;
-}
-
 /// Rx class for `String` Type.
 class RxString extends _RxImpl<String> {
   RxString([String initial]) {

+part of 'rx_impl.dart';
+
+/// Base Rx class for all num Rx's.
+class _BaseRxNum<T extends num> extends _RxImpl<T> {
+  /// Addition operator. */
+  num operator +(num other) => _value + other;
+
+  /// Subtraction operator.
+  num operator -(num other) => _value - other;
+
+  /// Multiplication operator.
+  num operator *(num other) => _value * other;
+
+  /// Euclidean modulo operator.
+  ///
+  /// Returns the remainder of the Euclidean division. The Euclidean division of
+  /// two integers `a` and `b` yields two integers `q` and `r` such that
+  /// `a == b * q + r` and `0 <= r < b.abs()`.
+  ///
+  /// The Euclidean division is only defined for integers, but can be easily
+  /// extended to work with doubles. In that case `r` may have a non-integer
+  /// value, but it still verifies `0 <= r < |b|`.
+  ///
+  /// The sign of the returned value `r` is always positive.
+  ///
+  /// See [remainder] for the remainder of the truncating division.
+  num operator %(num other) => _value % other;
+
+  /// Division operator.
+  double operator /(num other) => _value / other;
+
+  /// Truncating division operator.
+  ///
+  /// If either operand is a [double] then the result of the truncating division
+  /// `a ~/ b` is equivalent to `(a / b).truncate().toInt()`.
+  ///
+  /// If both operands are [int]s then `a ~/ b` performs the truncating
+  /// integer division.
+  int operator ~/(num other) => _value ~/ other;
+
+  /// Negate operator.
+  num operator -() => -_value;
+
+  /// Returns the remainder of the truncating division of `this` by [other].
+  ///
+  /// The result `r` of this operation satisfies:
+  /// `this == (this ~/ other) * other + r`.
+  /// As a consequence the remainder `r` has the same sign as the divider
+  /// `this`.
+  num remainder(num other) => _value.remainder(other);
+
+  /// Relational less than operator.
+  bool operator <(num other) => _value < other;
+
+  /// Relational less than or equal operator.
+  bool operator <=(num other) => _value <= other;
+
+  /// Relational greater than operator.
+  bool operator >(num other) => _value > other;
+
+  /// Relational greater than or equal operator.
+  bool operator >=(num other) => _value >= other;
+
+  /// True if the number is the double Not-a-Number value; otherwise, false.
+  bool get isNaN => _value.isNaN;
+
+  /// True if the number is negative; otherwise, false.
+  ///
+  /// Negative numbers are those less than zero, and the double `-0.0`.
+  bool get isNegative => _value.isNegative;
+
+  /// True if the number is positive infinity or negative infinity; otherwise,
+  /// false.
+  bool get isInfinite => _value.isInfinite;
+
+  /// True if the number is finite; otherwise, false.
+  ///
+  /// The only non-finite numbers are NaN, positive infinity, and
+  /// negative infinity.
+  bool get isFinite => _value.isFinite;
+
+  /// Returns the absolute value of this [num].
+  num abs() => _value.abs();
+
+  /// Returns minus one, zero or plus one depending on the sign and
+  /// numerical value of the number.
+  ///
+  /// Returns minus one if the number is less than zero,
+  /// plus one if the number is greater than zero,
+  /// and zero if the number is equal to zero.
+  ///
+  /// Returns NaN if the number is the double NaN value.
+  ///
+  /// Returns a number of the same type as this number.
+  /// For doubles, `-0.0.sign == -0.0`.
+  /// The result satisfies:
+  ///
+  ///     n == n.sign * n.abs()
+  ///
+  /// for all numbers `n` (except NaN, because NaN isn't `==` to itself).
+  num get sign => _value.sign;
+
+  /// Returns the integer closest to `this`.
+  ///
+  /// Rounds away from zero when there is no closest integer:
+  ///  `(3.5).round() == 4` and `(-3.5).round() == -4`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int round() => _value.round();
+
+  /// Returns the greatest integer no greater than `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int floor() => _value.floor();
+
+  /// Returns the least integer no smaller than `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int ceil() => _value.ceil();
+
+  /// Returns the integer obtained by discarding any fractional
+  /// digits from `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int truncate() => _value.truncate();
+
+  /// Returns the double integer value closest to `this`.
+  ///
+  /// Rounds away from zero when there is no closest integer:
+  ///  `(3.5).roundToDouble() == 4` and `(-3.5).roundToDouble() == -4`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is a
+  /// non-finite double value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`,
+  /// and `-0.0` is therefore considered closer to negative numbers than `0.0`.
+  /// This means that for a value, `d` in the range `-0.5 < d < 0.0`,
+  /// the result is `-0.0`.
+  ///
+  /// The result is always a double.
+  /// If this is a numerically large integer, the result may be an infinite
+  /// double.
+  double roundToDouble() => _value.roundToDouble();
+
+  /// Returns the greatest double integer value no greater than `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is a
+  /// non-finite double value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `0.0 < d < 1.0` will return `0.0`.
+  ///
+  /// The result is always a double.
+  /// If this is a numerically large integer, the result may be an infinite
+  /// double.
+  double floorToDouble() => _value.floorToDouble();
+
+  /// Returns the least double integer value no smaller than `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is a
+  /// non-finite double value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `-1.0 < d < 0.0` will return `-0.0`.
+  ///
+  /// The result is always a double.
+  /// If this is a numerically large integer, the result may be an infinite
+  /// double.
+  double ceilToDouble() => _value.ceilToDouble();
+
+  /// Returns the double integer value obtained by discarding any fractional
+  /// digits from the double value of `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is a
+  /// non-finite double value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `-1.0 < d < 0.0` will return `-0.0`, and
+  /// in the range `0.0 < d < 1.0` it will return 0.0.
+  ///
+  /// The result is always a double.
+  /// If this is a numerically large integer, the result may be an infinite
+  /// double.
+  double truncateToDouble() => _value.truncateToDouble();
+
+  /// Returns this [num] clamped to be in the range [lowerLimit]-[upperLimit].
+  ///
+  /// The comparison is done using [compareTo] and therefore takes `-0.0` into
+  /// account. This also implies that [double.nan] is treated as the maximal
+  /// double value.
+  ///
+  /// The arguments [lowerLimit] and [upperLimit] must form a valid range where
+  /// `lowerLimit.compareTo(upperLimit) <= 0`.
+  num clamp(num lowerLimit, num upperLimit) =>
+      _value.clamp(lowerLimit, upperLimit);
+
+  /// Truncates this [num] to an integer and returns the result as an [int]. */
+  int toInt() => _value.toInt();
+
+  /// Return this [num] as a [double].
+  ///
+  /// If the number is not representable as a [double], an
+  /// approximation is returned. For numerically large integers, the
+  /// approximation may be infinite.
+  double toDouble() => _value.toDouble();
+
+  /// Returns a decimal-point string-representation of `this`.
+  ///
+  /// Converts `this` to a [double] before computing the string representation.
+  ///
+  /// If the absolute value of `this` is greater or equal to `10^21` then this
+  /// methods returns an exponential representation computed by
+  /// `this.toStringAsExponential()`. Otherwise the result
+  /// is the closest string representation with exactly [fractionDigits] digits
+  /// after the decimal point. If [fractionDigits] equals 0 then the decimal
+  /// point is omitted.
+  ///
+  /// The parameter [fractionDigits] must be an integer satisfying:
+  /// `0 <= fractionDigits <= 20`.
+  ///
+  /// Examples:
+  ///
+  ///     1.toStringAsFixed(3);  // 1.000
+  ///     (4321.12345678).toStringAsFixed(3);  // 4321.123
+  ///     (4321.12345678).toStringAsFixed(5);  // 4321.12346
+  ///     123456789012345.toStringAsFixed(3);  // 123456789012345.000
+  ///     10000000000000000.toStringAsFixed(4); // 10000000000000000.0000
+  ///     5.25.toStringAsFixed(0); // 5
+  String toStringAsFixed(int fractionDigits) =>
+      _value.toStringAsFixed(fractionDigits);
+
+  /// Returns an exponential string-representation of `this`.
+  ///
+  /// Converts `this` to a [double] before computing the string representation.
+  ///
+  /// If [fractionDigits] is given then it must be an integer satisfying:
+  /// `0 <= fractionDigits <= 20`. In this case the string contains exactly
+  /// [fractionDigits] after the decimal point. Otherwise, without the
+  /// parameter, the returned string uses the shortest number of digits that
+  /// accurately represent [this].
+  ///
+  /// If [fractionDigits] equals 0 then the decimal point is omitted.
+  /// Examples:
+  ///
+  ///     1.toStringAsExponential();       // 1e+0
+  ///     1.toStringAsExponential(3);      // 1.000e+0
+  ///     123456.toStringAsExponential();  // 1.23456e+5
+  ///     123456.toStringAsExponential(3); // 1.235e+5
+  ///     123.toStringAsExponential(0);    // 1e+2
+  String toStringAsExponential([int fractionDigits]) =>
+      _value.toStringAsExponential(fractionDigits);
+
+  /// Converts `this` to a double and returns a string representation with
+  /// exactly [precision] significant digits.
+  ///
+  /// The parameter [precision] must be an integer satisfying:
+  /// `1 <= precision <= 21`.
+  ///
+  /// Examples:
+  ///
+  ///     1.toStringAsPrecision(2);       // 1.0
+  ///     1e15.toStringAsPrecision(3);    // 1.00e+15
+  ///     1234567.toStringAsPrecision(3); // 1.23e+6
+  ///     1234567.toStringAsPrecision(9); // 1234567.00
+  ///     12345678901234567890.toStringAsPrecision(20); // 12345678901234567168
+  ///     12345678901234567890.toStringAsPrecision(14); // 1.2345678901235e+19
+  ///     0.00000012345.toStringAsPrecision(15); // 1.23450000000000e-7
+  ///     0.0000012345.toStringAsPrecision(15);  // 0.00000123450000000000
+  String toStringAsPrecision(int precision) =>
+      _value.toStringAsPrecision(precision);
+}
+
+class RxNum extends _BaseRxNum<num> {}
+
+class RxDouble extends _BaseRxNum<double> {
+  RxDouble([double initial]) {
+    _value = initial;
+  }
+
+  /// Addition operator.
+  double operator +(num other) => _value + other;
+
+  /// Subtraction operator.
+  double operator -(num other) => _value - other;
+
+  /// Multiplication operator.
+  double operator *(num other) => _value * other;
+
+  double operator %(num other) => _value % other;
+
+  /// Division operator.
+  double operator /(num other) => _value / other;
+
+  /// Truncating division operator.
+  ///
+  /// The result of the truncating division `a ~/ b` is equivalent to
+  /// `(a / b).truncate()`.
+  int operator ~/(num other) => _value ~/ other;
+
+  /// Negate operator. */
+  double operator -() => -_value;
+
+  /// Returns the absolute value of this [double].
+  double abs() => _value.abs();
+
+  /// Returns the sign of the double's numerical value.
+  ///
+  /// Returns -1.0 if the value is less than zero,
+  /// +1.0 if the value is greater than zero,
+  /// and the value itself if it is -0.0, 0.0 or NaN.
+  double get sign => _value.sign;
+
+  /// Returns the integer closest to `this`.
+  ///
+  /// Rounds away from zero when there is no closest integer:
+  ///  `(3.5).round() == 4` and `(-3.5).round() == -4`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int round() => _value.round();
+
+  /// Returns the greatest integer no greater than `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int floor() => _value.floor();
+
+  /// Returns the least integer no smaller than `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int ceil() => _value.ceil();
+
+  /// Returns the integer obtained by discarding any fractional
+  /// digits from `this`.
+  ///
+  /// If `this` is not finite (`NaN` or infinity), throws an [UnsupportedError].
+  int truncate() => _value.truncate();
+
+  /// Returns the integer double value closest to `this`.
+  ///
+  /// Rounds away from zero when there is no closest integer:
+  ///  `(3.5).roundToDouble() == 4` and `(-3.5).roundToDouble() == -4`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is
+  /// not a finite value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`,
+  /// and `-0.0` is therefore considered closer to negative numbers than `0.0`.
+  /// This means that for a value, `d` in the range `-0.5 < d < 0.0`,
+  /// the result is `-0.0`.
+  double roundToDouble() => _value.roundToDouble();
+
+  /// Returns the greatest integer double value no greater than `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is
+  /// not a finite value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `0.0 < d < 1.0` will return `0.0`.
+  double floorToDouble() => _value.floorToDouble();
+
+  /// Returns the least integer double value no smaller than `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is
+  /// not a finite value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `-1.0 < d < 0.0` will return `-0.0`.
+  double ceilToDouble() => _value.ceilToDouble();
+
+  /// Returns the integer double value obtained by discarding any fractional
+  /// digits from `this`.
+  ///
+  /// If this is already an integer valued double, including `-0.0`, or it is
+  /// not a finite value, the value is returned unmodified.
+  ///
+  /// For the purpose of rounding, `-0.0` is considered to be below `0.0`.
+  /// A number `d` in the range `-1.0 < d < 0.0` will return `-0.0`, and
+  /// in the range `0.0 < d < 1.0` it will return 0.0.
+  double truncateToDouble() => _value.truncateToDouble();
+}
+
+class RxInt extends _BaseRxNum<int> {
+  RxInt([int initial]) {
+    _value = initial;
+  }
+
+  /// Bit-wise and operator.
+  ///
+  /// Treating both `this` and [other] as sufficiently large two's component
+  /// integers, the result is a number with only the bits set that are set in
+  /// both `this` and [other]
+  ///
+  /// If both operands are negative, the result is negative, otherwise
+  /// the result is non-negative.
+  int operator &(int other) => _value & other;
+
+  /// Bit-wise or operator.
+  ///
+  /// Treating both `this` and [other] as sufficiently large two's component
+  /// integers, the result is a number with the bits set that are set in either
+  /// of `this` and [other]
+  ///
+  /// If both operands are non-negative, the result is non-negative,
+  /// otherwise the result is negative.
+  int operator |(int other) => _value | other;
+
+  /// Bit-wise exclusive-or operator.
+  ///
+  /// Treating both `this` and [other] as sufficiently large two's component
+  /// integers, the result is a number with the bits set that are set in one,
+  /// but not both, of `this` and [other]
+  ///
+  /// If the operands have the same sign, the result is non-negative,
+  /// otherwise the result is negative.
+  int operator ^(int other) => _value ^ other;
+
+  /// The bit-wise negate operator.
+  ///
+  /// Treating `this` as a sufficiently large two's component integer,
+  /// the result is a number with the opposite bits set.
+  ///
+  /// This maps any integer `x` to `-x - 1`.
+  int operator ~() => ~_value;
+
+  /// Shift the bits of this integer to the left by [shiftAmount].
+  ///
+  /// Shifting to the left makes the number larger, effectively multiplying
+  /// the number by `pow(2, shiftIndex)`.
+  ///
+  /// There is no limit on the size of the result. It may be relevant to
+  /// limit intermediate values by using the "and" operator with a suitable
+  /// mask.
+  ///
+  /// It is an error if [shiftAmount] is negative.
+  int operator <<(int shiftAmount) => _value << shiftAmount;
+
+  /// Shift the bits of this integer to the right by [shiftAmount].
+  ///
+  /// Shifting to the right makes the number smaller and drops the least
+  /// significant bits, effectively doing an integer division by
+  ///`pow(2, shiftIndex)`.
+  ///
+  /// It is an error if [shiftAmount] is negative.
+  int operator >>(int shiftAmount) => _value >> shiftAmount;
+
+  /// Returns this integer to the power of [exponent] modulo [modulus].
+  ///
+  /// The [exponent] must be non-negative and [modulus] must be
+  /// positive.
+  int modPow(int exponent, int modulus) => _value.modPow(exponent, modulus);
+
+  /// Returns the modular multiplicative inverse of this integer
+  /// modulo [modulus].
+  ///
+  /// The [modulus] must be positive.
+  ///
+  /// It is an error if no modular inverse exists.
+  int modInverse(int modulus) => _value.modInverse(modulus);
+
+  /// Returns the greatest common divisor of this integer and [other].
+  ///
+  /// If either number is non-zero, the result is the numerically greatest
+  /// integer dividing both `this` and `other`.
+  ///
+  /// The greatest common divisor is independent of the order,
+  /// so `x.gcd(y)` is  always the same as `y.gcd(x)`.
+  ///
+  /// For any integer `x`, `x.gcd(x)` is `x.abs()`.
+  ///
+  /// If both `this` and `other` is zero, the result is also zero.
+  int gcd(int other) => _value.gcd(other);
+
+  /// Returns true if and only if this integer is even.
+  bool get isEven => _value.isEven;
+
+  /// Returns true if and only if this integer is odd.
+  bool get isOdd => _value.isOdd;
+
+  /// Returns the minimum number of bits required to store this integer.
+  ///
+  /// The number of bits excludes the sign bit, which gives the natural length
+  /// for non-negative (unsigned) values.  Negative values are complemented to
+  /// return the bit position of the first bit that differs from the sign bit.
+  ///
+  /// To find the number of bits needed to store the value as a signed value,
+  /// add one, i.e. use `x.bitLength + 1`.
+  /// ```
+  /// x.bitLength == (-x-1).bitLength
+  ///
+  /// 3.bitLength == 2;     // 00000011
+  /// 2.bitLength == 2;     // 00000010
+  /// 1.bitLength == 1;     // 00000001
+  /// 0.bitLength == 0;     // 00000000
+  /// (-1).bitLength == 0;  // 11111111
+  /// (-2).bitLength == 1;  // 11111110
+  /// (-3).bitLength == 2;  // 11111101
+  /// (-4).bitLength == 2;  // 11111100
+  /// ```
+  int get bitLength => _value.bitLength;
+
+  /// Returns the least significant [width] bits of this integer as a
+  /// non-negative number (i.e. unsigned representation).  The returned value
+  /// has zeros in all bit positions higher than [width].
+  /// ```
+  /// (-1).toUnsigned(5) == 31   // 11111111  ->  00011111
+  /// ```
+  /// This operation can be used to simulate arithmetic from low level
+  /// languages.
+  /// For example, to increment an 8 bit quantity:
+  /// ```
+  /// q = (q + 1).toUnsigned(8);
+  /// ```
+  /// `q` will count from `0` up to `255` and then wrap around to `0`.
+  ///
+  /// If the input fits in [width] bits without truncation, the result is the
+  /// same as the input.  The minimum width needed to avoid truncation of `x` is
+  /// given by `x.bitLength`, i.e.
+  /// ```
+  /// x == x.toUnsigned(x.bitLength);
+  /// ```
+  int toUnsigned(int width) => _value.toUnsigned(width);
+
+  /// Returns the least significant [width] bits of this integer, extending the
+  /// highest retained bit to the sign.  This is the same as truncating the
+  /// value to fit in [width] bits using an signed 2-s complement
+  /// representation.
+  /// The returned value has the same bit value in all positions higher than
+  /// [width].
+  ///
+  /// ```
+  ///                                V--sign bit-V
+  /// 16.toSigned(5) == -16   //  00010000 -> 11110000
+  /// 239.toSigned(5) == 15   //  11101111 -> 00001111
+  ///                                ^           ^
+  /// ```
+  /// This operation can be used to simulate arithmetic from low level
+  /// languages.
+  /// For example, to increment an 8 bit signed quantity:
+  /// ```
+  /// q = (q + 1).toSigned(8);
+  /// ```
+  /// `q` will count from `0` up to `127`, wrap to `-128` and count back up to
+  /// `127`.
+  ///
+  /// If the input value fits in [width] bits without truncation, the result is
+  /// the same as the input.  The minimum width needed to avoid truncation
+  /// of `x` is `x.bitLength + 1`, i.e.
+  /// ```
+  /// x == x.toSigned(x.bitLength + 1);
+  /// ```
+  int toSigned(int width) => _value.toSigned(width);
+
+  /// Return the negative value of this integer.
+  ///
+  /// The result of negating an integer always has the opposite sign, except
+  /// for zero, which is its own negation.
+  int operator -() => -_value;
+
+  /// Returns the absolute value of this integer.
+  ///
+  /// For any integer `x`, the result is the same as `x < 0 ? -x : x`.
+  int abs() => _value.abs();
+
+  /// Returns the sign of this integer.
+  ///
+  /// Returns 0 for zero, -1 for values less than zero and
+  /// +1 for values greater than zero.
+  int get sign => _value.sign;
+
+  /// Returns `this`.
+  int round() => _value.round();
+
+  /// Returns `this`.
+  int floor() => _value.floor();
+
+  /// Returns `this`.
+  int ceil() => _value.ceil();
+
+  /// Returns `this`.
+  int truncate() => _value.truncate();
+
+  /// Returns `this.toDouble()`.
+  double roundToDouble() => _value.roundToDouble();
+
+  /// Returns `this.toDouble()`.
+  double floorToDouble() => _value.floorToDouble();
+
+  /// Returns `this.toDouble()`.
+  double ceilToDouble() => _value.ceilToDouble();
+
+  /// Returns `this.toDouble()`.
+  double truncateToDouble() => _value.truncateToDouble();
+}
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