feat(examples): Implement p/demo/dequeue

examples/gno.land/p/demo/queue/errors.gno

@@ -0,0 +1,14 @@
+package queue
+
+import (
+	"errors"
+)
+
+// Error definitions for various edge cases
+var (
+	ErrResourceError    = errors.New("resource error: queue is full")
+	ErrEmptyArrayPop    = errors.New("empty array pop: queue is empty")
+	ErrArrayOutOfBounds = errors.New("array out of bounds")
+
+	ErrNonExistedValue = errors.New("non-existed value")
+)

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

@@ -0,0 +1,6 @@
+module gno.land/p/demo/queue
+
+require (
+	gno.land/p/demo/avl v0.0.0-latest
+	gno.land/p/demo/seqid v0.0.0-latest
+)

examples/gno.land/p/demo/queue/queue.gno

@@ -0,0 +1,154 @@
+package queue
+
+import (
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/seqid"
+)
+
+// Queue is a queue data structure that stores elements of any type.
+type Queue struct {
+	begin seqid.ID  // Index of the front element
+	end   seqid.ID  // Index after the last element
+	data  *avl.Tree // Storage for queue elements
+}
+
+// NewQueue creates and initializes a new queue.
+func NewQueue() *Queue {
+	return &Queue{
+		begin: seqid.ID(0),
+		end:   seqid.ID(0),
+		data:  avl.NewTree(),
+	}
+}
+
+// PushBack adds an element to the end of the queue.
+// Returns an error if the queue is full.
+func (q *Queue) PushBack(value interface{}) error {
+	if q.end+1 == q.begin {
+		return ErrResourceError
+	}
+
+	q.data.Set(q.end.String(), value)
+
+	q.end++
+
+	return nil
+}
+
+// PopBack removes and returns the element at the end of the queue.
+// Returns an error if the queue is empty.
+func (q *Queue) PopBack() (interface{}, error) {
+	if q.begin == q.end {
+		return nil, ErrEmptyArrayPop
+	}
+
+	q.end--
+	value, ok := q.data.Get(q.end.String())
+	if !ok {
+		return nil, ErrNonExistedValue
+	}
+
+	q.data.Remove(q.end.String())
+
+	return value, nil
+}
+
+// PushFront adds an element to the front of the queue.
+// Returns an error if the queue is full.
+func (q *Queue) PushFront(value interface{}) error {
+	if q.begin-1 == q.end {
+		return ErrResourceError
+	}
+
+	q.begin--
+	q.data.Set(q.begin.String(), value)
+
+	return nil
+}
+
+// PopFront removes and returns the element at the front of the queue.
+// Returns an error if the queue is empty.
+func (q *Queue) PopFront() (interface{}, error) {
+	if q.begin == q.end {
+		return nil, ErrEmptyArrayPop
+	}
+
+	value, ok := q.data.Get(q.begin.String())
+	if !ok {
+		return nil, ErrNonExistedValue
+	}
+
+	q.data.Remove(q.begin.String())
+
+	q.begin++
+
+	return value, nil
+}
+
+// Front returns the element at the front of the queue without removing it.
+// Returns an error if the queue is empty.
+func (q *Queue) Front() (interface{}, error) {
+	if q.Empty() {
+		return nil, ErrArrayOutOfBounds
+	}
+
+	id := q.begin
+
+	value, ok := q.data.Get(id.String())
+	if !ok {
+		return nil, ErrNonExistedValue
+	}
+
+	return value, nil
+}
+
+// Back returns the element at the end of the queue without removing it.
+// Returns an error if the queue is empty.
+func (q *Queue) Back() (interface{}, error) {
+	if q.Empty() {
+		return nil, ErrArrayOutOfBounds
+	}
+
+	id := q.end - 1
+
+	value, ok := q.data.Get(id.String())
+	if !ok {
+		return nil, ErrNonExistedValue
+	}
+
+	return value, nil
+}
+
+// At returns the element at the specified index in the queue.
+// Returns an error if the index is out of bounds.
+func (q *Queue) At(index uint64) (interface{}, error) {
+	if index >= q.Length() {
+		return nil, ErrArrayOutOfBounds
+	}
+
+	id := q.begin + seqid.ID(index)
+
+	value, ok := q.data.Get(id.String())
+	if !ok {
+		return nil, ErrNonExistedValue
+	}
+
+	return value, nil
+}
+
+// Clear removes all elements from the queue.
+func (q *Queue) Clear() {
+	q.begin = 0
+	q.end = 0
+	q.data = avl.NewTree()
+}
+
+// Length returns the number of elements in the queue.
+func (q *Queue) Length() uint64 {
+	return uint64(q.end - q.begin)
+}
+
+// Empty returns true if the queue is empty, false otherwise.
+func (q *Queue) Empty() bool {
+	return q.end == q.begin
+}