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use streams with lazy array

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Matthew Butterick 6 years ago
parent 4d7cdfe3ee
commit 44d66b7782
3 changed files with 41 additions and 41 deletions
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18
xenomorph/xenomorph/redo.rkt
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@ -0,0 +1,18 @@
#lang racket/base
(require racket/require)
(define-syntax-rule (r+p ID ...)
(begin (require ID ...) (provide (all-from-out ID ...))))
(r+p "redo/array.rkt"
"redo/bitfield.rkt"
"redo/buffer.rkt"
"redo/enum.rkt"
"redo/lazy-array.rkt"
"redo/number.rkt"
"redo/optional.rkt"
"redo/pointer.rkt"
"redo/reserved.rkt"
"redo/string.rkt"
"redo/struct.rkt"
"redo/versioned-struct.rkt")

49
xenomorph/xenomorph/redo/lazy-array.rkt
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@ -1,37 +1,12 @@
#lang racket/base
(require "helper.rkt" "util.rkt" "number.rkt" "array.rkt" racket/dict sugar/unstable/dict)
(require "helper.rkt" "util.rkt" "number.rkt" "array.rkt" racket/stream racket/dict sugar/unstable/dict)
(provide (all-defined-out))
#|
approximates
https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
|#
(define (get ila index)
(unless (<= 0 index (sub1 (inner-lazy-array-len ila)))
(raise-argument-error 'LazyArray:get (format "index in range 0 to ~a" (sub1 (inner-lazy-array-len ila))) index))
(dict-ref! (inner-lazy-array-item-cache ila) index (λ ()
(define port (inner-lazy-array-port ila))
(define orig-pos (pos port))
(pos port (+ (inner-lazy-array-starting-pos ila)
(* (size (inner-lazy-array-type ila) #f (inner-lazy-array-ctx ila)) index)))
(define new-item (decode (inner-lazy-array-type ila) port #:parent (inner-lazy-array-ctx ila)))
(pos port orig-pos)
new-item)))
(define (to-list ila)
(for/list ([i (in-range (inner-lazy-array-len ila))])
(get ila i)))
(define (xlazy-array->list ila) (to-list ila))
(struct inner-lazy-array (type len port ctx starting-pos item-cache) #:transparent)
(define (+inner-lazy-array type [len #f] [port-in #f] [ctx #f])
(define port (->input-port port-in))
(define starting-pos (pos port))
(inner-lazy-array type len port ctx starting-pos (mhasheqv)))
(define (xlazy-array-decode xla [port-arg (current-input-port)] #:parent [parent #f])
(define port (->input-port port-arg))
(define starting-pos (pos port)) ; ! placement matters. `resolve-length` will change `pos`
@ -42,15 +17,22 @@ https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
'_currentOffset 0
'_length (xarray-base-len xla))
parent)])
(define res (+inner-lazy-array (xarray-base-type xla) decoded-len port parent))
(define starting-pos (pos port))
(define res (for/stream ([index (in-range decoded-len)])
(define type (xarray-base-type xla))
(define orig-pos (pos port))
(pos port (+ starting-pos (* (size type #f parent) index)))
(define new-item (decode type port #:parent parent))
(pos port orig-pos)
new-item))
(pos port (+ (pos port) (* decoded-len (size (xarray-base-type xla) #f parent))))
res))
(define (xlazy-array-encode xla val [port-arg (current-output-port)] #:parent [parent #f])
(xarray-encode xla (if (inner-lazy-array? val) (to-list val) val) port-arg #:parent parent))
(xarray-encode xla (if (stream? val) (stream->list val) val) port-arg #:parent parent))
(define (xlazy-array-size xla [val #f] [ctx #f])
(xarray-size xla (if (inner-lazy-array? val) (to-list val) val) ctx))
(xarray-size xla (if (stream? val) (stream->list val) val) ctx))
;; xarray-base holds type and len fields
(struct xlazy-array xarray-base () #:transparent
@ -66,7 +48,6 @@ https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
(raise-argument-error '+xarray "length-resolvable?" len))
(xlazy-array type len))
(module+ test
(require rackunit "number.rkt")
(define bstr #"ABCD1234")
@ -74,10 +55,10 @@ https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
(define la (+xlazy-array uint8 4))
(define ila (decode la ds))
(check-equal? (pos ds) 4)
(check-equal? (get ila 1) 66)
(check-equal? (get ila 3) 68)
(check-equal? (stream-ref ila 1) 66)
(check-equal? (stream-ref ila 3) 68)
(check-equal? (pos ds) 4)
(check-equal? (xlazy-array->list ila) '(65 66 67 68))
(check-equal? (stream->list ila) '(65 66 67 68))
(define la2 (+xlazy-array int16be (λ (t) 4)))
(check-equal? (encode la2 '(1 2 3 4) #f) #"\0\1\0\2\0\3\0\4")
(check-equal? (to-list (decode la2 (open-input-bytes #"\0\1\0\2\0\3\0\4"))) '(1 2 3 4)))
(check-equal? (stream->list (decode la2 (open-input-bytes #"\0\1\0\2\0\3\0\4"))) '(1 2 3 4)))

15
xenomorph/xenomorph/redo/test/lazy-array-test.rkt
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@ -1,6 +1,7 @@
#lang racket/base
(require rackunit
racket/dict
racket/stream
"../array.rkt"
"../helper.rkt"
"../number.rkt"
@ -17,26 +18,26 @@ https://github.com/mbutterick/restructure/blob/master/test/LazyArray.coffee
(define array (+xlazy-array uint8 4))
(define arr (decode array))
(check-false (xarray? arr))
(check-equal? (inner-lazy-array-len arr) 4)
(check-equal? (stream-length arr) 4)
(check-equal? (pos (current-input-port)) 4)
(check-equal? (get arr 0) 1)
(check-equal? (get arr 1) 2)
(check-equal? (get arr 2) 3)
(check-equal? (get arr 3) 4)))
(check-equal? (stream-ref arr 0) 1)
(check-equal? (stream-ref arr 1) 2)
(check-equal? (stream-ref arr 2) 3)
(check-equal? (stream-ref arr 3) 4)))
(test-case
"should be able to convert to an array"
(parameterize ([current-input-port (open-input-bytes (bytes 1 2 3 4 5))])
(define array (+xlazy-array uint8 4))
(define arr (decode array))
(check-equal? (xlazy-array->list arr) '(1 2 3 4))))
(check-equal? (stream->list arr) '(1 2 3 4))))
(test-case
"decode should decode length as number before array"
(parameterize ([current-input-port (open-input-bytes (bytes 4 1 2 3 4 5))])
(define array (+xlazy-array uint8 uint8))
(define arr (decode array))
(check-equal? (xlazy-array->list arr) '(1 2 3 4))))
(check-equal? (stream->list arr) '(1 2 3 4))))
(test-case
"size should work with xlazy-arrays"

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