; -*- Mode: Scheme; Syntax: Scheme; Package: data; -*-

; This is file stack.scm.

;;;; Stack management

(define *stack* (unassigned))

(define (set-stack! stack)
  (set! *stack* stack))

(define (push x)
  (set! *stack* (cons x *stack*))
  *stack*)

(define (pop)
  (let ((arg (car *stack*)))
    (set! *stack* (cdr *stack*))
    arg))

(define-macro (push-vector . rest)
  `(let ((v (vector ,@rest *stack*)))
     (set! *stack* v)
     v))

(define (pop-vector size)
  (let ((v *stack*))
    (assert (= size (- (vector-length v) 1)))
    (set! *stack* (vector-ref *stack* size))
    v))

(define push-size pair-size)
(define (stack-vector-size n) (vector-size (+ n 1)))

(define available-on-stack? available?)