super_bit_field 0.0.2

A bit field code generator base on super_annotation for dart.

A bit field code generator base on super_annotation for dart.

Getting started

First, add super_annotations, super_bit_field as dependencies, and build_runner as a dev_dependency.

pub add super_annotations super_bit_field
pub add --dev build_runner

For every pub command prefix it with either dart or flutter depending on your project.

Usage

Asume you have a dart file named test_bit_field.dart in your project. You can define a bit field class in it like this:

@BitFieldGen(runAfter: [BitFieldGen.addPartOfDirective])
library test_bit_field;

import 'package:super_bit_field/super_bit_field.dart';
part 'test_bit_field.g.dart';


@BitField(32)
class TestBitField {
  @Bits(2)
  late int twoBits; // 0-1

  @Bits(1)
  late int oneBit; // 2-2

  @Bits(3)
  late int threeBits; // 3-5

  late int value;

  factory TestBitField(int value, [
    GetSetHook<int> hook
  ]) = _TestBitField;
}

Then run build_runner to generate the part file.

pub run build_runner build

For every pub command prefix it with either dart or flutter depending on your project.

The generated part file named test_bit_field.g.dart will be like this:

part of 'test_bit_field.dart';

class _TestBitField implements TestBitField {
  _TestBitField(
    int value, [
    GetSetHook<int>? hook,
  ])  : _value = value,
        _hook = hook;

  static const int length = 32;

  static const int musk = ((0x01 << length) - 1);

  int _value = 0;

  final GetSetHook<int>? _hook;

  static const int twoBitsBits = 2;

  static const int oneBitBits = 1;

  static const int threeBitsBits = 3;

  static const int twoBitsOffset = 0;

  static const int oneBitOffset = 2;

  static const int threeBitsOffset = 3;

  static const int twoBitsMask = ((0x01 << twoBitsBits) - 1) << twoBitsOffset;

  static const int oneBitMask = ((0x01 << oneBitBits) - 1) << oneBitOffset;

  static const int threeBitsMask =
      ((0x01 << threeBitsBits) - 1) << threeBitsOffset;

  @override
  int get value {
    if (_hook != null && _hook.onGet != null) {
      _value = _hook.onGet!();
    }
    return _value;
  }

  @override
  set value(value) {
    _value = value;
    if (_hook != null && _hook.onSet != null) {
      _hook.onSet!(_value);
    }
  }

  @override
  int get twoBits => ((value & twoBitsMask) >> twoBitsOffset);

  @override
  int get oneBit => ((value & oneBitMask) >> oneBitOffset);

  @override
  int get threeBits => ((value & threeBitsMask) >> threeBitsOffset);

  @override
  set twoBits(int v) =>
      value = (value & ~twoBitsMask) | ((v << twoBitsOffset) & twoBitsMask);

  @override
  set oneBit(int v) =>
      value = (value & ~oneBitMask) | ((v << oneBitOffset) & oneBitMask);

  @override
  set threeBits(int v) => value =
      (value & ~threeBitsMask) | ((v << threeBitsOffset) & threeBitsMask);
}

Then you can operate the bit field in the class you defined.

void main() {
  var bitField = TestBitField(0);
  bitField.twoBits = 1;
  bitField.oneBit = 1;
  bitField.threeBits = 1;
  print(bitField.value.toRadixString(2));
  print(bitField.twoBits);
  print(bitField.oneBit);
  print(bitField.threeBits);
}

You can also opperate a external int value with a bit field object by using GetSetHook.

void main() {
    int value = 0;
    TestBitField testBitField = TestBitField(value, GetSetHook<int>(onSet: (int v) {
        value = v;
    }, onGet: () {
        return value;
    }));
    testBitField.twoBits = 2;
    print(value); // 2
    testBitField.oneBit = 1;
    print(value); // 6
    testBitField.threeBits = 5;
    print(value); // 46
}