1-) FLUTTER - yığın yapısı stack use kullanımı

flutter pub add stack

import 'package:stack/stack.dart' as st2;

st2.Stack<int> stack = st2.Stack<int>();

stack.push(-1);

int node = stack.pop();

kaynak : https://pub.dev/packages/stack/example

Stack sınıfını ovveride ederek metotlarını değiştirebilirsin

import 'dart:collection';
import 'dart:core' as core;
import 'dart:core';

import 'package:stack/illegal_operation_exception.dart';

class Stack<T> {
  final ListQueue<T> _list = ListQueue();

  final int noLimit = -1;

  /// the maximum number of entries allowed on the stack. -1 = no limit.
  int _sizeMax = 0;

  /// Default constructor sets the maximum stack size to 'no limit.'
  Stack() {
    _sizeMax = noLimit;
  }

  /// Constructor in which you can specify maximum number of entries.
  /// This maximum is a limit that is enforced as entries are pushed on to the stack
  /// to prevent stack growth beyond a maximum size. There is no pre-allocation of
  /// slots for entries at any time in this library.
  Stack.sized(int sizeMax) {
    if(sizeMax < 2) {
      throw IllegalOperationException(
        'Error: stack size must be 2 entries or more '
      );
    }
    else {
      _sizeMax = sizeMax;
    }
  }

  /// check if the stack is empty.
  bool get isEmpty => _list.isEmpty;

  /// check if the stack is not empty.
  bool get isNotEmpty => _list.isNotEmpty;

  /// push element in top of the stack.
  void push(T e) {
    if(_sizeMax == noLimit || _list.length < _sizeMax) {
      _list.addLast(e);
    }
    else {
      throw IllegalOperationException(
        'Error: cannot add element. Stack already at maximum size of: ${_sizeMax} elements');
    }
  }

  /// get the top of the stack and delete it.
  T pop() {
    if (isEmpty) {
      throw IllegalOperationException(
        'Can\'t use pop with empty stack\n consider '
        'checking for size or isEmpty before calling pop',
      );
    }
    T res = _list.last;
    _list.removeLast();
    return res;
  }

  /// get the top of the stack without deleting it.
  T top() {
    if (isEmpty) {
      throw IllegalOperationException(
        'Can\'t use top with empty stack\n consider '
        'checking for size or isEmpty before calling top',
      );
    }
    return _list.last;
  }

  /// get the size of the stack.
  int size() {
    return _list.length;
  }

  /// get the length of the stack.
  int get length => size();

  /// returns true if element is found in the stack
  bool contains(T x) {
    return _list.contains(x);
  }

  /// print stack
  void print() {
    for (var item in List<T>.from(_list).reversed) {
      core.print(item);
    }
  }

  String printString() {
    String list ="";
    for (var item in List<String>.from(_list).reversed) {
      if(item=="-1"){
        continue;
      }
      list = item+" -> "+list;
    }

    int last =list.lastIndexOf(" -> ");
    if(last!=-1){
      list = list.substring(0,last);
    }

    return list;
  }
}