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package genstack
// stack is a wrapper around an array implementing a stack.
//
// We cannot use slice to represent the stack because append might change the
// pointer value of the slice. That would be an issue in GenStack
// implementation.
type stack[T any] struct {
arr []T
}
// push pushes a new element at the top of a stack.
func (s *stack[T]) push(vs ...T) { s.arr = append(s.arr, vs...) }
// pop pops the stack top-most element.
//
// If stack length is zero, this method panics.
func (s *stack[T]) pop() T {
idx := s.len() - 1
val := s.arr[idx]
// Avoid memory leak
var zero T
s.arr[idx] = zero
s.arr = s.arr[:idx]
return val
}
// takeAll returns all elements in the stack in order as they are stored - i.e.
// the top-most stack element is the last one.
func (s *stack[T]) takeAll() []T {
arr := s.arr
s.arr = nil
return arr
}
// len returns number of elements in the stack.
func (s *stack[T]) len() int { return len(s.arr) }
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