Learning Dart [Advanced]

/*
 * Advanced Dart
 * https://www.tutorialspoint.com/dart_programming/dart_programming_html_dom.htm
 * https://dartpad.dartlang.org/
 */

/*
 * Package Manager: pub (can download Various Libraries)
 * Package Metadata: pubsec.yaml (contains dependencies)
 * YAML = Yet Another Markup Language
 */

import 'dart:collection' show Queue;    // To use Queue (Only import Queue)
import 'dart:io';
import 'dart:html';

/*
 * _ in _identifier means private (Encapsulation)
 */

typedef PrintSymbol(String _string);

DollarSign(String _string) {
  print('${_string}\$');
}

HashtagSign(String _string) {
  print('${_string}#');
}

AmperstandSign(String _string) {
  print('${_string}&');
}

SignOperator(String _string, PrintSymbol sym) {
  sym(_string);
}

class Animal {
  String name;
  int age;

  Animal() {
    print("A new animal is being created");
  }

  // Multiple Constructor
  Animal.namedConst(String name) {
    this.name = name;
    print('${name} is an animal now');
  }

  void walk() {
    print('Animal is walking');
  }
}

class LivingBeing {
  void breathe() {
    print('Living Being is breathing');
  }
}

class Mammal implements Animal, LivingBeing {
  // Multiple interfaces is ok
  @override
  int age;

  @override
  String name;

  @override
  void walk() {
    print('Mammal is walking');
  }

  @override
  void breathe() {
    print('Mammal is breathing');
  }

}

class Human extends LivingBeing {
  // Single Inheritance
  // There is no multiple inheritance (multi-level is ok)
  String name;
  static int totalHuman;

  Human() {
    super.breathe();
  }

  String get humanName {
    return name;
  }

  void set humanName(name) {
    this.name = name;
  }
}

void main() {
  int _int;
  String _string;

  // Dart is OOP
  Animal dog = new Animal.namedConst("Doge");
  print(dog.name);
  dog.age = 5;
  dog.walk();
  print(dog.age);
  print("");

  // Interfaces
  Mammal cow = new Mammal();
  cow.breathe();
  print("");

  // Static
  Human.totalHuman = 0;
  // Super
  Human john = new Human();
  // Setter & Getter
  john.humanName = "John Doe";
  print(john.humanName);
  // Inheritance
  john.breathe();
  Human.totalHuman++;

  // Cascade Operator (Sequence Call via Object)
  cow..walk()..breathe();
  print('');

  /*
   * Dart has no Array but Collection
   *    - List
   *    - Set (Has unique Value)
   *    - Maps (Key : Value)
   *    - Queue (First in, First out)
   */
  Set _set = new Set();
  _set.add('x');
  _set.add('y');
  _set.add('z');
  _set.add('x');    // Unique, will be skipped

  print('Set = ${_set}');

  // Queue should import 'dart:collection'
  Queue _queue = new Queue();
  _queue.add(10);
  _queue.add(20);
  _queue.add(30);
  _queue.add(40);

  print('Queue = ${_queue}');

  Iterator _iterator = _queue.iterator;

  while (_iterator.moveNext()) {
    print('Queue interator = ${_iterator.current}');
  }
  print('');

  // Try Catch
  try {
    _int = 5 ~/ 0;
  }
  catch (e) {
    print(e);
        print('Cannot divide by zero');
    }

  _int = -5;

  try {
    print(foo(_int));
  }
  catch (e) {
    print('Throw: ${e}');
  }
  print("");

  // Typedef
  _string = "This is ";
  PrintSymbol sym;
  sym = DollarSign;
  sym(_string);
  sym = HashtagSign;
  sym(_string);
  sym = AmperstandSign;
  sym(_string);
    SignOperator(_string, DollarSign);
  sym(_string);
  print("");

  // Input
  print('Input: ');
  try {
    _string = stdin.readLineSync();
  } catch (e) {
    print(e);
  }
  print(_string);

  // HTML
  var div = querySelector('div');
  div.text = "The text changed";
}

foo(int _int) {
  // Return Type not specified = dynamic
  if (_int < 0) {
    throw new FormatException();
  }

  return _int;
}