stack.go

package gds

// Stack is a LIFO (last-in, first-out) collection.
// It is not safe for concurrent use.
type Stack[T any] struct {
	items []T
}

// NewStack returns an empty Stack.
func NewStack[T any]() *Stack[T] { return &Stack[T]{} }

// Push adds one or more items onto the top of the stack.
func (s *Stack[T]) Push(items ...T) {
	s.items = append(s.items, items...)
}

// Pop removes and returns the top element.
// Returns the zero value and false if the stack is empty.
func (s *Stack[T]) Pop() (T, bool) {
	if len(s.items) == 0 {
		var zero T
		return zero, false
	}
	top := s.items[len(s.items)-1]
	s.items = s.items[:len(s.items)-1]
	return top, true
}

// Peek returns the top element without removing it.
// Returns the zero value and false if the stack is empty.
func (s *Stack[T]) Peek() (T, bool) {
	if len(s.items) == 0 {
		var zero T
		return zero, false
	}
	return s.items[len(s.items)-1], true
}

// Len returns the number of elements in the stack.
func (s *Stack[T]) Len() int { return len(s.items) }

// IsEmpty reports whether the stack has no elements.
func (s *Stack[T]) IsEmpty() bool { return len(s.items) == 0 }

// Clear removes all elements from the stack.
func (s *Stack[T]) Clear() { s.items = nil }