intmap-remove
intmap-ref
intmap-next
+ intmap-prev
intmap-union
intmap-intersect))
*branch-mask*)))
(lp (vector-ref node idx) shift)))))))))))
-(define (intmap-next bs i)
+(define* (intmap-next bs #:optional i)
(define (visit-branch node shift i)
(let lp ((i i) (idx (logand (ash i (- shift)) *branch-mask*)))
(and (< idx *branch-size*)
(let ((i (visit-node root shift i)))
(and i (+ min i))))))))
+(define* (intmap-prev bs #:optional i)
+ (define (visit-branch node shift i)
+ (let lp ((i i) (idx (logand (ash i (- shift)) *branch-mask*)))
+ (and (<= 0 idx)
+ (or (visit-node (vector-ref node idx) shift i)
+ (lp (1- (round-down i shift)) (1- idx))))))
+ (define (visit-node node shift i)
+ (and node
+ (if (zero? shift)
+ i
+ (visit-branch node (- shift *branch-bits*) i))))
+ (match bs
+ (($ <intmap> min shift root)
+ (let* ((i (if (and i (< i (+ min (ash 1 shift))))
+ (- i min)
+ (1- (ash 1 shift)))))
+ (and (<= 0 i)
+ (let ((i (visit-node root shift i)))
+ (and i (+ min i))))))))
+
(define* (intmap-union a b #:optional (meet meet-error))
;; Union A and B from index I; the result will be fresh.
(define (union-branches/fresh shift a b i fresh)