feat(examples): add todolist package & realm (gnolang#1811)

<!-- please provide a detailed description of the changes made in this
pull request. -->

<details><summary>Contributors' checklist...</summary>

- [x] Added new tests, or not needed, or not feasible
- [ ] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [ ] Updated the official documentation or not needed
- [ ] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [ ] Added references to related issues and PRs
- [ ] Provided any useful hints for running manual tests
- [ ] Added new benchmarks to [generated
graphs](https://gnoland.github.io/benchmarks), if any. More info
[here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md).
</details>

examples/gno.land/p/demo/todolist/gno.mod

@@ -0,0 +1,3 @@
+module gno.land/p/demo/todolist
+
+require gno.land/p/demo/avl v0.0.0-latest

examples/gno.land/p/demo/todolist/todolist.gno

@@ -0,0 +1,63 @@
+package todolist
+
+import (
+	"std"
+	"strconv"
+
+	"gno.land/p/demo/avl"
+)
+
+type TodoList struct {
+	Title string
+	Tasks *avl.Tree
+	Owner std.Address
+}
+
+type Task struct {
+	Title string
+	Done  bool
+}
+
+func NewTodoList(title string) *TodoList {
+	return &TodoList{
+		Title: title,
+		Tasks: avl.NewTree(),
+		Owner: std.GetOrigCaller(),
+	}
+}
+
+func NewTask(title string) *Task {
+	return &Task{
+		Title: title,
+		Done:  false,
+	}
+}
+
+func (tl *TodoList) AddTask(id int, task *Task) {
+	tl.Tasks.Set(strconv.Itoa(id), task)
+}
+
+func ToggleTaskStatus(task *Task) {
+	task.Done = !task.Done
+}
+
+func (tl *TodoList) RemoveTask(taskId string) {
+	tl.Tasks.Remove(taskId)
+}
+
+func (tl *TodoList) GetTasks() []*Task {
+	tasks := make([]*Task, 0, tl.Tasks.Size())
+	tl.Tasks.Iterate("", "", func(key string, value interface{}) bool {
+		tasks = append(tasks, value.(*Task))
+		return false
+	})
+	return tasks
+}
+
+func (tl *TodoList) GetTodolistOwner() std.Address {
+	return tl.Owner
+}
+
+func (tl *TodoList) GetTodolistTitle() string {
+	return tl.Title
+}

examples/gno.land/p/demo/todolist/todolist_test.gno

@@ -0,0 +1,81 @@
+package todolist
+
+import (
+	"std"
+	"testing"
+)
+
+func TestNewTodoList(t *testing.T) {
+	title := "My Todo List"
+	todoList := NewTodoList(title)
+
+	if todoList.GetTodolistTitle() != title {
+		t.Errorf("Expected title %q, got %q", title, todoList.GetTodolistTitle())
+	}
+
+	if len(todoList.GetTasks()) != 0 {
+		t.Errorf("Expected 0 tasks, got %d", len(todoList.GetTasks()))
+	}
+
+	if todoList.GetTodolistOwner() != std.GetOrigCaller() {
+		t.Errorf("Expected owner %v, got %v", std.GetOrigCaller(), todoList.GetTodolistOwner())
+	}
+}
+
+func TestNewTask(t *testing.T) {
+	title := "My Task"
+	task := NewTask(title)
+
+	if task.Title != title {
+		t.Errorf("Expected title %q, got %q", title, task.Title)
+	}
+
+	if task.Done {
+		t.Errorf("Expected task to be not done, but it is done")
+	}
+}
+
+func TestAddTask(t *testing.T) {
+	todoList := NewTodoList("My Todo List")
+	task := NewTask("My Task")
+
+	todoList.AddTask(1, task)
+
+	tasks := todoList.GetTasks()
+	if len(tasks) != 1 {
+		t.Errorf("Expected 1 task, got %d", len(tasks))
+	}
+
+	if tasks[0] != task {
+		t.Errorf("Expected task %v, got %v", task, tasks[0])
+	}
+}
+
+func TestToggleTaskStatus(t *testing.T) {
+	task := NewTask("My Task")
+
+	ToggleTaskStatus(task)
+
+	if !task.Done {
+		t.Errorf("Expected task to be done, but it is not done")
+	}
+
+	ToggleTaskStatus(task)
+
+	if task.Done {
+		t.Errorf("Expected task to be not done, but it is done")
+	}
+}
+
+func TestRemoveTask(t *testing.T) {
+	todoList := NewTodoList("My Todo List")
+	task := NewTask("My Task")
+	todoList.AddTask(1, task)
+
+	todoList.RemoveTask("1")
+
+	tasks := todoList.GetTasks()
+	if len(tasks) != 0 {
+		t.Errorf("Expected 0 tasks, got %d", len(tasks))
+	}
+}

examples/gno.land/r/demo/todolist/gno.mod

@@ -0,0 +1,8 @@
+module gno.land/r/demo/todolist
+
+require (
+	gno.land/p/demo/avl v0.0.0-latest
+	gno.land/p/demo/seqid v0.0.0-latest
+	gno.land/p/demo/todolist v0.0.0-latest
+	gno.land/p/demo/ufmt v0.0.0-latest
+)

examples/gno.land/r/demo/todolist/todolist.gno

@@ -0,0 +1,176 @@
+package todolistrealm
+
+import (
+	"bytes"
+	"strconv"
+
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/seqid"
+	"gno.land/p/demo/todolist"
+	"gno.land/p/demo/ufmt"
+)
+
+// State variables
+var (
+	todolistTree *avl.Tree
+	tlid         seqid.ID
+)
+
+// Constructor
+func init() {
+	todolistTree = avl.NewTree()
+}
+
+func NewTodoList(title string) (int, string) {
+	// Create new Todolist
+	tl := todolist.NewTodoList(title)
+	// Update AVL tree with new state
+	tlid.Next()
+	todolistTree.Set(strconv.Itoa(int(tlid)), tl)
+	return int(tlid), "created successfully"
+}
+
+func AddTask(todolistID int, title string) string {
+	// Get Todolist from AVL tree
+	tl, ok := todolistTree.Get(strconv.Itoa(todolistID))
+	if !ok {
+		panic("Todolist not found")
+	}
+
+	// get the number of tasks in the todolist
+	id := tl.(*todolist.TodoList).Tasks.Size()
+
+	// create the task
+	task := todolist.NewTask(title)
+
+	// Cast raw data from tree into Todolist struct
+	tl.(*todolist.TodoList).AddTask(id, task)
+
+	return "task added successfully"
+}
+
+func ToggleTaskStatus(todolistID int, taskID int) string {
+	// Get Todolist from AVL tree
+	tl, ok := todolistTree.Get(strconv.Itoa(todolistID))
+	if !ok {
+		panic("Todolist not found")
+	}
+
+	// Get the task from the todolist
+	task, found := tl.(*todolist.TodoList).Tasks.Get(strconv.Itoa(taskID))
+	if !found {
+		panic("Task not found")
+	}
+
+	// Change the status of the task
+	todolist.ToggleTaskStatus(task.(*todolist.Task))
+
+	return "task status changed successfully"
+}
+
+func RemoveTask(todolistID int, taskID int) string {
+	// Get Todolist from AVL tree
+	tl, ok := todolistTree.Get(strconv.Itoa(todolistID))
+	if !ok {
+		panic("Todolist not found")
+	}
+
+	// Get the task from the todolist
+	_, ok = tl.(*todolist.TodoList).Tasks.Get(strconv.Itoa(taskID))
+	if !ok {
+		panic("Task not found")
+	}
+
+	// Change the status of the task
+	tl.(*todolist.TodoList).RemoveTask(strconv.Itoa(taskID))
+
+	return "task status changed successfully"
+}
+
+func RemoveTodoList(todolistID int) string {
+	// Get Todolist from AVL tree
+	_, ok := todolistTree.Get(strconv.Itoa(todolistID))
+	if !ok {
+		panic("Todolist not found")
+	}
+
+	// Remove the todolist
+	todolistTree.Remove(strconv.Itoa(todolistID))
+
+	return "Todolist removed successfully"
+}
+
+func Render(path string) string {
+	if path == "" {
+		return renderHomepage()
+	}
+
+	return "unknown page"
+}
+
+func renderHomepage() string {
+	// Define empty buffer
+	var b bytes.Buffer
+
+	b.WriteString("# Welcome to ToDolist\n\n")
+
+	// If no todolists have been created
+	if todolistTree.Size() == 0 {
+		b.WriteString("### No todolists available currently!")
+		return b.String()
+	}
+
+	// Iterate through AVL tree
+	todolistTree.Iterate("", "", func(key string, value interface{}) bool {
+		// cast raw data from tree into Todolist struct
+		tl := value.(*todolist.TodoList)
+
+		// Add Todolist name
+		b.WriteString(
+			ufmt.Sprintf(
+				"## Todolist #%s: %s\n",
+				key, // Todolist ID
+				tl.GetTodolistTitle(),
+			),
+		)
+
+		// Add Todolist owner
+		b.WriteString(
+			ufmt.Sprintf(
+				"#### Todolist owner : %s\n",
+				tl.GetTodolistOwner(),
+			),
+		)
+
+		// List all todos that are currently Todolisted
+		if todos := tl.GetTasks(); len(todos) > 0 {
+			b.WriteString(
+				ufmt.Sprintf("Currently Todo tasks: %d\n\n", len(todos)),
+			)
+
+			for index, todo := range todos {
+				b.WriteString(
+					ufmt.Sprintf("#%d - %s  ", index, todo.Title),
+				)
+				// displays a checked box if task is marked as done, an empty box if not
+				if todo.Done {
+					b.WriteString(
+						"☑\n\n",
+					)
+					continue
+				}
+
+				b.WriteString(
+					"☐\n\n",
+				)
+			}
+		} else {
+			b.WriteString("No tasks in this list currently\n")
+		}
+
+		b.WriteString("\n")
+		return false
+	})
+
+	return b.String()
+}