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Restoring iset merge node logic.

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Alex Shinn 2014-05-13 23:01:09 +09:00
parent d7e65edc96
commit a886737b20
1 changed files with 46 additions and 4 deletions
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50
lib/chibi/iset/constructors.scm
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@ -3,7 +3,7 @@
;; Utilities for constructing and joining isets.
(define bits-thresh 128) ; within 128 we join into a bitmap
(define bits-max 512) ; don't make bitmaps larger than this
;;(define bits-max 512) ; don't make bitmaps larger than this
(define (bit-set n index)
(bitwise-ior n (arithmetic-shift 1 index)))
@ -65,9 +65,46 @@
(if (and bits (= bits (range->bits (iset-start iset) (iset-end iset))))
(iset-bits-set! iset #f))))
(define (iset-should-merge-left? a b)
(and (< (- (iset-start a) (iset-end b))
bits-thresh)
(or (not (iset-left a))
(> (iset-start b) (iset-max-end (iset-left a))))))
(define (iset-should-merge-right? a b)
(and (< (- (iset-start b) (iset-end a))
bits-thresh)
(or (not (iset-right a))
(< (iset-end b) (iset-min-start (iset-right a))))))
(define (iset-merge-left! a b)
(if (or (iset-bits a) (iset-bits b)
(< (+ 1 (iset-end b)) (iset-start a)))
(let* ((a-bits (or (iset-bits a)
(range->bits (iset-start a) (iset-end a))))
(b-bits (or (iset-bits b)
(range->bits (iset-start b) (iset-end b))))
(shift (- (iset-start a) (iset-start b)))
(bits (bitwise-ior b-bits (arithmetic-shift a-bits shift))))
(iset-bits-set! a bits)))
(iset-start-set! a (iset-start b)))
(define (iset-merge-right! a b)
(if (or (iset-bits a) (iset-bits b)
(< (+ 1 (iset-end a)) (iset-start b)))
(let* ((a-bits (or (iset-bits a)
(range->bits (iset-start a) (iset-end a))))
(b-bits (or (iset-bits b)
(range->bits (iset-start b) (iset-end b))))
(shift (- (iset-start b) (iset-start a)))
(bits (bitwise-ior a-bits (arithmetic-shift b-bits shift))))
(iset-bits-set! a bits)))
(iset-end-set! a (iset-end b)))
(define (iset-adjoin1! is n)
(iset-adjoin-node! is (%make-iset n n #f #f #f)))
;; adjoin just the node b (ignoring left/right) to the full iset a
(define (iset-adjoin-node! a b)
(cond
((iset-empty? a)
@ -85,11 +122,15 @@
;; aaaa...
;; ...bbbb
((< b-end a-start)
(iset-adjoin-node-left! a b))
(if (iset-should-merge-left? a b)
(iset-merge-left! a b)
(iset-adjoin-node-left! a b)))
;; ...aaaa
;; bbbb...
((> b-start a-end)
(iset-adjoin-node-right! a b))
(if (iset-should-merge-right? a b)
(iset-merge-right! a b)
(iset-adjoin-node-right! a b)))
;; ...aaaaa...
;; ...bb...
((and (>= b-start a-start) (<= b-end a-end))
@ -97,7 +138,8 @@
(let ((b-bits (arithmetic-shift
(or b-bits (range->bits b-start b-end))
(- b-start a-start))))
(iset-bits-set! a (bitwise-ior a-bits b-bits)))))
(iset-bits-set! a (bitwise-ior a-bits b-bits))
(iset-squash-bits! a))))
(else
;; general case: split, recurse, join sides
(let ((ls (iset-node-split b a-start a-end)))