File size: 29,027 Bytes
3dcad1f |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 |
;;; Functional name maps
;;; Copyright (C) 2014-2017,2019 Free Software Foundation, Inc.
;;;
;;; This library is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;;
;;; Some CPS passes need to perform a flow analysis in which every
;;; program point has an associated map over some set of labels or
;;; variables. The naive way to implement this is with an array of
;;; arrays, but this has N^2 complexity, and it really can hurt us.
;;;
;;; Instead, this module provides a functional map that can share space
;;; between program points, reducing the amortized space complexity of
;;; the representations down to O(n log n). Adding entries to the
;;; mapping and lookup are O(log n). Intersection and union between
;;; intmaps that share state are fast, too.
;;;
;;; Code:
(define-module (language cps intmap)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module (ice-9 match)
#:use-module ((ice-9 threads) #:select (current-thread))
#:export (empty-intmap
intmap?
transient-intmap?
persistent-intmap
transient-intmap
intmap-add
intmap-add!
intmap-replace
intmap-replace!
intmap-remove
intmap-ref
intmap-next
intmap-prev
intmap-fold
intmap-fold-right
intmap-union
intmap-intersect))
;; Persistent sparse intmaps.
(define-syntax-rule (define-inline name val)
(define-syntax name (identifier-syntax val)))
;; FIXME: This should make an actual atomic reference.
(define-inlinable (make-atomic-reference value)
(list value))
(define-inlinable (get-atomic-reference reference)
(car reference))
(define-inlinable (set-atomic-reference! reference value)
(set-car! reference value))
(define-inline *branch-bits* 5)
(define-inline *branch-size* (ash 1 *branch-bits*))
(define-inline *branch-size-with-edit* (1+ *branch-size*))
(define-inline *edit-index* *branch-size*)
(define-inline *branch-mask* (1- *branch-size*))
(define-record-type <intmap>
(make-intmap min shift root)
intmap?
(min intmap-min)
(shift intmap-shift)
(root intmap-root))
(define-record-type <transient-intmap>
(make-transient-intmap min shift root edit)
transient-intmap?
(min transient-intmap-min set-transient-intmap-min!)
(shift transient-intmap-shift set-transient-intmap-shift!)
(root transient-intmap-root set-transient-intmap-root!)
(edit transient-intmap-edit set-transient-intmap-edit!))
(define *absent* (list 'absent))
(define-inlinable (absent? x)
(eq? x *absent*))
(define-inlinable (present? x)
(not (absent? x)))
(define-inlinable (new-branch edit)
(let ((vec (make-vector *branch-size-with-edit* *absent*)))
(vector-set! vec *edit-index* edit)
vec))
(define-inlinable (clone-branch-with-edit branch edit)
(let ((new (vector-copy branch)))
(vector-set! new *edit-index* edit)
new))
(define (clone-branch-and-set branch i elt)
(let ((new (clone-branch-with-edit branch #f)))
(vector-set! new i elt)
new))
(define-inlinable (assert-readable! root-edit)
(unless (eq? (get-atomic-reference root-edit) (current-thread))
(error "Transient intmap owned by another thread" root-edit)))
(define-inlinable (writable-branch branch root-edit)
(let ((edit (vector-ref branch *edit-index*)))
(if (eq? root-edit edit)
branch
(clone-branch-with-edit branch root-edit))))
(define (branch-empty? branch)
(let lp ((i 0))
(or (= i *branch-size*)
(and (absent? (vector-ref branch i))
(lp (1+ i))))))
(define-inlinable (round-down min shift)
(logand min (lognot (1- (ash 1 shift)))))
(define empty-intmap (make-intmap 0 0 *absent*))
(define (add-level min shift root)
(let* ((shift* (+ shift *branch-bits*))
(min* (round-down min shift*))
(idx (logand (ash (- min min*) (- shift))
*branch-mask*))
(root* (new-branch #f)))
(vector-set! root* idx root)
(make-intmap min* shift* root*)))
(define (make-intmap/prune min shift root)
(if (zero? shift)
(make-intmap min shift root)
(let lp ((i 0) (elt #f))
(cond
((< i *branch-size*)
(if (present? (vector-ref root i))
(if elt
(make-intmap min shift root)
(lp (1+ i) i))
(lp (1+ i) elt)))
(elt
(let ((shift (- shift *branch-bits*)))
(make-intmap/prune (+ min (ash elt shift))
shift
(vector-ref root elt))))
;; Shouldn't be reached...
(else empty-intmap)))))
(define (meet-error old new)
(error "Multiple differing values and no meet procedure defined" old new))
(define* (transient-intmap #:optional (source empty-intmap))
(match source
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
source)
(($ <intmap> min shift root)
(let ((edit (make-atomic-reference (current-thread))))
(make-transient-intmap min shift root edit)))))
(define* (persistent-intmap #:optional (source empty-intmap))
(match source
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
;; Make a fresh reference, causing any further operations on this
;; transient to clone its root afresh.
(set-transient-intmap-edit! source
(make-atomic-reference (current-thread)))
;; Clear the reference to the current thread, causing our edited
;; data structures to be persistent again.
(set-atomic-reference! edit #f)
(if min
(make-intmap min shift root)
empty-intmap))
(($ <intmap>)
source)))
(define* (intmap-add! map i val #:optional (meet meet-error))
(define (ensure-branch! root idx)
(let ((edit (vector-ref root *edit-index*))
(v (vector-ref root idx)))
(if (absent? v)
(let ((v (new-branch edit)))
(vector-set! root idx v)
v)
(let ((v* (writable-branch v edit)))
(unless (eq? v v*)
(vector-set! root idx v*))
v*))))
(define (adjoin! i shift root)
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift)) *branch-mask*)))
(if (zero? shift)
(let ((node (vector-ref root idx)))
(unless (eq? node val)
(vector-set! root idx (if (present? node) (meet node val) val))))
(adjoin! i shift (ensure-branch! root idx)))))
(match map
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
(cond
((< i 0)
;; The power-of-two spanning trick doesn't work across 0.
(error "Intmaps can only map non-negative integers." i))
((absent? root)
(set-transient-intmap-min! map i)
(set-transient-intmap-shift! map 0)
(set-transient-intmap-root! map val))
((and (<= min i) (< i (+ min (ash 1 shift))))
;; Add element to map; level will not change.
(if (zero? shift)
(unless (eq? root val)
(set-transient-intmap-root! map (meet root val)))
(let ((root* (writable-branch root edit)))
(unless (eq? root root*)
(set-transient-intmap-root! map root*))
(adjoin! (- i min) shift root*))))
(else
(let lp ((min min)
(shift shift)
(root root))
(let* ((shift* (+ shift *branch-bits*))
(min* (round-down min shift*))
(idx (logand (ash (- min min*) (- shift))
*branch-mask*))
(root* (new-branch edit)))
(vector-set! root* idx root)
(cond
((and (<= min* i) (< i (+ min* (ash 1 shift*))))
(set-transient-intmap-min! map min*)
(set-transient-intmap-shift! map shift*)
(set-transient-intmap-root! map root*)
(adjoin! (- i min*) shift* root*))
(else
(lp min* shift* root*)))))))
map)
(($ <intmap>)
(intmap-add! (transient-intmap map) i val meet))))
(define* (intmap-add map i val #:optional (meet meet-error))
(define (adjoin i shift root)
(if (zero? shift)
(cond
((eq? root val) root)
((absent? root) val)
(else (meet root val)))
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift)) *branch-mask*)))
(if (absent? root)
(let ((root* (new-branch #f))
(node* (adjoin i shift root)))
(vector-set! root* idx node*)
root*)
(let* ((node (vector-ref root idx))
(node* (adjoin i shift node)))
(if (eq? node node*)
root
(clone-branch-and-set root idx node*)))))))
(match map
(($ <intmap> min shift root)
(cond
((< i 0)
;; The power-of-two spanning trick doesn't work across 0.
(error "Intmaps can only map non-negative integers." i))
((absent? root)
;; Add first element.
(make-intmap i 0 val))
((and (<= min i) (< i (+ min (ash 1 shift))))
;; Add element to map; level will not change.
(let ((old-root root)
(root (adjoin (- i min) shift root)))
(if (eq? root old-root)
map
(make-intmap min shift root))))
((< i min)
;; Rebuild the tree by unioning two intmaps.
(intmap-union (intmap-add empty-intmap i val error) map error))
(else
;; Add a new level and try again.
(intmap-add (add-level min shift root) i val error))))
(($ <transient-intmap>)
(intmap-add (persistent-intmap map) i val meet))))
(define* (intmap-replace! map i val #:optional (meet (lambda (old new) new)))
"Like intmap-add!, but requires that @var{i} was present in the map
already, and always calls the meet procedure."
(define (not-found)
(error "not found" i))
(define (ensure-branch! root idx)
(let ((edit (vector-ref root *edit-index*))
(v (vector-ref root idx)))
(when (absent? v) (not-found))
(let ((v* (writable-branch v edit)))
(unless (eq? v v*)
(vector-set! root idx v*))
v*)))
(define (adjoin! i shift root)
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift)) *branch-mask*)))
(if (zero? shift)
(let ((node (vector-ref root idx)))
(when (absent? node) (not-found))
(vector-set! root idx (meet node val)))
(adjoin! i shift (ensure-branch! root idx)))))
(match map
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
(cond
((< i 0)
;; The power-of-two spanning trick doesn't work across 0.
(error "Intmaps can only map non-negative integers." i))
((and (present? root) (<= min i) (< i (+ min (ash 1 shift))))
(if (zero? shift)
(set-transient-intmap-root! map (meet root val))
(let ((root* (writable-branch root edit)))
(unless (eq? root root*)
(set-transient-intmap-root! map root*))
(adjoin! (- i min) shift root*))))
(else
(not-found)))
map)
(($ <intmap>)
(intmap-add! (transient-intmap map) i val meet))))
(define* (intmap-replace map i val #:optional (meet (lambda (old new) new)))
"Like intmap-add, but requires that @var{i} was present in the map
already, and always calls the meet procedure."
(define (not-found)
(error "not found" i))
(define (adjoin i shift root)
(if (zero? shift)
(if (absent? root)
(not-found)
(meet root val))
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift)) *branch-mask*)))
(if (absent? root)
(not-found)
(let* ((node (vector-ref root idx))
(node* (adjoin i shift node)))
(if (eq? node node*)
root
(clone-branch-and-set root idx node*)))))))
(match map
(($ <intmap> min shift root)
(cond
((< i 0)
;; The power-of-two spanning trick doesn't work across 0.
(error "Intmaps can only map non-negative integers." i))
((and (present? root) (<= min i) (< i (+ min (ash 1 shift))))
(let ((old-root root)
(root (adjoin (- i min) shift root)))
(if (eq? root old-root)
map
(make-intmap min shift root))))
(else (not-found))))
(($ <transient-intmap>)
(intmap-replace (persistent-intmap map) i val meet))))
(define (intmap-remove map i)
(define (remove i shift root)
(cond
((zero? shift) *absent*)
(else
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift)) *branch-mask*))
(node (vector-ref root idx)))
(if (absent? node)
root
(let ((node* (remove i shift node)))
(if (eq? node node*)
root
(clone-branch-and-set root idx node*))))))))
(match map
(($ <intmap> min shift root)
(cond
((absent? root) map)
((and (<= min i) (< i (+ min (ash 1 shift))))
;; Add element to map; level will not change.
(let ((root* (remove (- i min) shift root)))
(if (eq? root root*)
map
(if (absent? root*)
empty-intmap
(make-intmap/prune min shift root*)))))
(else map)))
(($ <transient-intmap>)
(intmap-remove (persistent-intmap map) i))))
(define* (intmap-ref map i #:optional (not-found (lambda (i)
(error "not found" i))))
(define (absent) (not-found i))
(define (ref min shift root)
(if (zero? shift)
(if (and min (= i min) (present? root))
root
(absent))
(if (and (<= min i) (< i (+ min (ash 1 shift))))
(let ((i (- i min)))
(let lp ((node root) (shift shift))
(if (present? node)
(if (= shift *branch-bits*)
(let ((node (vector-ref node (logand i *branch-mask*))))
(if (present? node)
node
(absent)))
(let* ((shift (- shift *branch-bits*))
(idx (logand (ash i (- shift))
*branch-mask*)))
(lp (vector-ref node idx) shift)))
(absent))))
(absent))))
(match map
(($ <intmap> min shift root)
(ref min shift root))
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
(ref min shift root))))
(define* (intmap-next map #:optional i)
(define (visit-branch node shift i)
(let lp ((i i) (idx (logand (ash i (- shift)) *branch-mask*)))
(and (< idx *branch-size*)
(or (visit-node (vector-ref node idx) shift i)
(let ((inc (ash 1 shift)))
(lp (+ (round-down i shift) inc) (1+ idx)))))))
(define (visit-node node shift i)
(and (present? node)
(if (zero? shift)
i
(visit-branch node (- shift *branch-bits*) i))))
(define (next min shift root)
(let ((i (if (and i (< min i))
(- i min)
0)))
(and (< i (ash 1 shift))
(let ((i (visit-node root shift i)))
(and i (+ min i))))))
(match map
(($ <intmap> min shift root)
(next min shift root))
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
(next min shift root))))
(define* (intmap-prev map #: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 (present? node)
(if (zero? shift)
i
(visit-branch node (- shift *branch-bits*) i))))
(define (prev 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))))))
(match map
(($ <intmap> min shift root)
(prev min shift root))
(($ <transient-intmap> min shift root edit)
(assert-readable! edit)
(prev min shift root))))
(define-syntax-rule (make-intmap-folder forward? seed ...)
(lambda (f map seed ...)
(define (visit-branch node shift min seed ...)
(let ((shift (- shift *branch-bits*)))
(if (zero? shift)
(let lp ((i (if forward? 0 (1- *branch-size*))) (seed seed) ...)
(if (if forward? (< i *branch-size*) (<= 0 i))
(let ((elt (vector-ref node i)))
(call-with-values (lambda ()
(if (present? elt)
(f (+ i min) elt seed ...)
(values seed ...)))
(lambda (seed ...)
(lp (if forward? (1+ i) (1- i)) seed ...))))
(values seed ...)))
(let lp ((i (if forward? 0 (1- *branch-size*))) (seed seed) ...)
(if (if forward? (< i *branch-size*) (<= 0 i))
(let ((elt (vector-ref node i)))
(call-with-values
(lambda ()
(if (present? elt)
(visit-branch elt shift (+ min (ash i shift))
seed ...)
(values seed ...)))
(lambda (seed ...)
(lp (if forward? (1+ i) (1- i)) seed ...))))
(values seed ...))))))
(let fold ((map map))
(match map
(($ <intmap> min shift root)
(cond
((absent? root) (values seed ...))
((zero? shift) (f min root seed ...))
(else (visit-branch root shift min seed ...))))
(($ <transient-intmap>)
(fold (persistent-intmap map)))))))
(define intmap-fold
(case-lambda
((f map)
((make-intmap-folder #t) f map))
((f map seed)
((make-intmap-folder #t seed) f map seed))
((f map seed0 seed1)
((make-intmap-folder #t seed0 seed1) f map seed0 seed1))
((f map seed0 seed1 seed2)
((make-intmap-folder #t seed0 seed1 seed2) f map seed0 seed1 seed2))))
(define intmap-fold-right
(case-lambda
((f map)
((make-intmap-folder #f) f map))
((f map seed)
((make-intmap-folder #f seed) f map seed))
((f map seed0 seed1)
((make-intmap-folder #f seed0 seed1) f map seed0 seed1))
((f map seed0 seed1 seed2)
((make-intmap-folder #f seed0 seed1 seed2) f map seed0 seed1 seed2))))
(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)
(let lp ((i 0))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(vector-set! fresh i (union shift a-child b-child))
(lp (1+ i))))
(else fresh))))
;; Union A and B from index I; the result may be eq? to A.
(define (union-branches/a shift a b i)
(let lp ((i i))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(if (eq? a-child b-child)
(lp (1+ i))
(let ((child (union shift a-child b-child)))
(cond
((eq? a-child child)
(lp (1+ i)))
(else
(let ((result (clone-branch-and-set a i child)))
(union-branches/fresh shift a b (1+ i) result))))))))
(else a))))
;; Union A and B; the may could be eq? to either.
(define (union-branches shift a b)
(let lp ((i 0))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(if (eq? a-child b-child)
(lp (1+ i))
(let ((child (union shift a-child b-child)))
(cond
((eq? a-child child)
(union-branches/a shift a b (1+ i)))
((eq? b-child child)
(union-branches/a shift b a (1+ i)))
(else
(let ((result (clone-branch-and-set a i child)))
(union-branches/fresh shift a b (1+ i) result))))))))
;; Seems they are the same but not eq?. Odd.
(else a))))
(define (union shift a-node b-node)
(cond
((absent? a-node) b-node)
((absent? b-node) a-node)
((eq? a-node b-node) a-node)
((zero? shift) (meet a-node b-node))
(else (union-branches (- shift *branch-bits*) a-node b-node))))
(match (cons a b)
((($ <intmap> a-min a-shift a-root) . ($ <intmap> b-min b-shift b-root))
(cond
((not (= b-shift a-shift))
;; Hoist the map with the lowest shift to meet the one with the
;; higher shift.
(if (< b-shift a-shift)
(intmap-union a (add-level b-min b-shift b-root) meet)
(intmap-union (add-level a-min a-shift a-root) b meet)))
((not (= b-min a-min))
;; Nodes at the same shift but different minimums will cover
;; disjoint ranges (due to the round-down call on min). Hoist
;; both until they cover the same range.
(intmap-union (add-level a-min a-shift a-root)
(add-level b-min b-shift b-root)
meet))
(else
;; At this point, A and B cover the same range.
(let ((root (union a-shift a-root b-root)))
(cond
((eq? root a-root) a)
((eq? root b-root) b)
(else (make-intmap a-min a-shift root)))))))))
(define* (intmap-intersect a b #:optional (meet meet-error))
;; Intersect A and B from index I; the result will be fresh.
(define (intersect-branches/fresh shift a b i fresh)
(let lp ((i 0))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(vector-set! fresh i (intersect shift a-child b-child))
(lp (1+ i))))
((branch-empty? fresh) *absent*)
(else fresh))))
;; Intersect A and B from index I; the result may be eq? to A.
(define (intersect-branches/a shift a b i)
(let lp ((i i))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(if (eq? a-child b-child)
(lp (1+ i))
(let ((child (intersect shift a-child b-child)))
(cond
((eq? a-child child)
(lp (1+ i)))
(else
(let ((result (clone-branch-and-set a i child)))
(intersect-branches/fresh shift a b (1+ i) result))))))))
(else a))))
;; Intersect A and B; the may could be eq? to either.
(define (intersect-branches shift a b)
(let lp ((i 0))
(cond
((< i *branch-size*)
(let* ((a-child (vector-ref a i))
(b-child (vector-ref b i)))
(if (eq? a-child b-child)
(lp (1+ i))
(let ((child (intersect shift a-child b-child)))
(cond
((eq? a-child child)
(intersect-branches/a shift a b (1+ i)))
((eq? b-child child)
(intersect-branches/a shift b a (1+ i)))
(else
(let ((result (clone-branch-and-set a i child)))
(intersect-branches/fresh shift a b (1+ i) result))))))))
;; Seems they are the same but not eq?. Odd.
(else a))))
(define (intersect shift a-node b-node)
(cond
((or (absent? a-node) (absent? b-node)) *absent*)
((eq? a-node b-node) a-node)
((zero? shift) (meet a-node b-node))
(else (intersect-branches (- shift *branch-bits*) a-node b-node))))
(define (different-mins lo-min lo-shift lo-root hi-min hi-shift hi lo-is-a?)
(cond
((<= lo-shift hi-shift)
;; If LO has a lower shift and a lower min, it is disjoint. If
;; it has the same shift and a different min, it is also
;; disjoint.
empty-intmap)
(else
(let* ((lo-shift (- lo-shift *branch-bits*))
(lo-idx (ash (- hi-min lo-min) (- lo-shift))))
(if (>= lo-idx *branch-size*)
;; HI has a lower shift, but it not within LO.
empty-intmap
(let ((lo-root (vector-ref lo-root lo-idx)))
(if (absent? lo-root)
empty-intmap
(let ((lo (make-intmap (+ lo-min (ash lo-idx lo-shift))
lo-shift
lo-root)))
(if lo-is-a?
(intmap-intersect lo hi meet)
(intmap-intersect hi lo meet))))))))))
(define (different-shifts-same-min min hi-shift hi-root lo lo-is-a?)
(let ((hi-root (vector-ref hi-root 0)))
(if (absent? hi-root)
empty-intmap
(let ((hi (make-intmap min
(- hi-shift *branch-bits*)
hi-root)))
(if lo-is-a?
(intmap-intersect lo hi meet)
(intmap-intersect hi lo meet))))))
(match (cons a b)
((($ <intmap> a-min a-shift a-root) . ($ <intmap> b-min b-shift b-root))
(cond
((< a-min b-min)
(different-mins a-min a-shift a-root b-min b-shift b #t))
((< b-min a-min)
(different-mins b-min b-shift b-root a-min a-shift a #f))
((< a-shift b-shift)
(different-shifts-same-min b-min b-shift b-root a #t))
((< b-shift a-shift)
(different-shifts-same-min a-min a-shift a-root b #f))
(else
;; At this point, A and B cover the same range.
(let ((root (intersect a-shift a-root b-root)))
(cond
((absent? root) empty-intmap)
((eq? root a-root) a)
((eq? root b-root) b)
(else (make-intmap/prune a-min a-shift root)))))))))
(define (intmap->alist intmap)
(reverse (intmap-fold acons intmap '())))
(define (intmap-key-ranges intmap)
(call-with-values
(lambda ()
(intmap-fold (lambda (k v start end closed)
(cond
((not start) (values k k closed))
((= k (1+ end)) (values start k closed))
(else (values k k (acons start end closed)))))
intmap #f #f '()))
(lambda (start end closed)
(reverse (if start (acons start end closed) closed)))))
(define (range-string ranges)
(string-join (map (match-lambda
((start . start)
(format #f "~a" start))
((start . end)
(format #f "~a-~a" start end)))
ranges)
","))
(define (print-helper port tag intmap)
(let ((ranges (intmap-key-ranges intmap)))
(match ranges
(()
(format port "#<~a>" tag))
(((0 . _) . _)
(format port "#<~a ~a>" tag (range-string ranges)))
(((min . end) . ranges)
(let ((ranges (map (match-lambda
((start . end) (cons (- start min) (- end min))))
(acons min end ranges))))
(format port "#<~a ~a+~a>" tag min (range-string ranges)))))))
(define (print-intmap intmap port)
(print-helper port "intmap" intmap))
(define (print-transient-intmap intmap port)
(print-helper port "transient-intmap" intmap))
(set-record-type-printer! <intmap> print-intmap)
(set-record-type-printer! <transient-intmap> print-transient-intmap)
|