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Updates to for/vector, for/flvector forms and documentation.

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- Now the faster forms take a #:length keyword to designate the length
  of the vector to pre-allocate.

- The for/[fl]vector forms take multiple body expressions and set the
  vector component to the value of the last one.

- When given a #:length argument, the for/vector and for/flvector
  forms check that the iteration is not exceeding the given length,
  raising exn:fail if it does.

- Test cases for the multiple body expressions and the exception for
  excessive iterations have been added.

- Doc modifications to bring the docs in line with the new forms.

- Doc modifications to note that the #:length versions of the form
*may* all the computation to be performed more efficiently, and
stating that it "is an error" if the given length-expr does not
produce a valid length for a vector that matches the number of
iterations for the loop.

- Note that no test is made for a number of loop iterations that is
  smaller than the given vector length.  Also, the for*/[fl]vector
  forms do not optimize when given a #:length argument.  These are
  areas for future improvement.
This commit is contained in:
Will M. Farr 2010-08-21 01:00:04 -05:00 committed by Sam Tobin-Hochstadt
parent c15871a028
commit 3d016150a3
7 changed files with 82 additions and 43 deletions
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28
collects/racket/flonum.rkt
View File

@ -50,24 +50,26 @@
(define-syntax for/flvector
(lambda (stx)
(syntax-case stx ()
((for/flvector (for-clause ...) body)
((for/flvector (for-clause ...) body ...)
(syntax/loc stx
(list->flvector (for/list (for-clause ...) body))))
((for/flvector len-expr (for-clause ...) body)
(list->flvector (for/list (for-clause ...) body ...))))
((for/flvector #:length len-expr (for-clause ...) body ...)
(syntax/loc stx
(let ((flv (make-flvector len-expr)))
(for ((i (in-naturals))
for-clause
...)
(flvector-set! flv i body))
flv))))))
(let ((len len-expr))
(let ((flv (make-flvector len)))
(for ((i (in-naturals))
for-clause
...)
(when (fx>= i len) (error 'for/flvector "too many iterations for vector of length ~a" len))
(flvector-set! flv i (begin body ...)))
flv)))))))
(define-syntax for*/flvector
(lambda (stx)
(syntax-case stx ()
((for*/flvector (for-clause ...) body)
((for*/flvector (for-clause ...) body ...)
(syntax/loc stx
(list->flvector (for*/list (for-clause ...) body))))
((for*/flvector length-expr (for-clause ...) body)
(list->flvector (for*/list (for-clause ...) body ...))))
((for*/flvector #:length len-expr (for-clause ...) body ...)
(syntax/loc stx
(for*/flvector (for-clause ...) body))))))
(for*/flvector (for-clause ...) body ...))))))

19
collects/racket/private/for.rkt
View File

@ -912,27 +912,28 @@
(define-syntax for/vector
(lambda (stx)
(syntax-case stx ()
((for/vector (for-clause ...) body)
((for/vector (for-clause ...) body ...)
(syntax/loc stx
(list->vector (for/list (for-clause ...) body))))
((for/vector length-expr (for-clause ...) body)
(list->vector (for/list (for-clause ...) body ...))))
((for/vector #:length size-expr (for-clause ...) body ...)
(syntax/loc stx
(let ((len length-expr))
(let ((len size-expr))
(let ((v (make-vector len)))
(for ((i (in-naturals))
for-clause ...)
(vector-set! v i body))
(when (>= i len) (error 'for/vector "too many iterations for vector of length ~a" len))
(vector-set! v i (begin body ...)))
v)))))))
(define-syntax for*/vector
(lambda (stx)
(syntax-case stx ()
((for*/vector (for-clause ...) body)
((for*/vector (for-clause ...) body ...)
(syntax/loc stx
(list->vector (for*/list (for-clause ...) body))))
((for*/vector length-expr (for-clause ...) body)
(list->vector (for*/list (for-clause ...) body ...))))
((for*/vector #:length len-expr (for-clause ...) body ...)
(syntax/loc stx
(for*/vector (for-clause ...) body))))))
(for*/vector (for-clause ...) body ...))))))
(define-for-syntax (do-for/lists for/fold-id stx)
(syntax-case stx ()

4
collects/scribblings/guide/for.scrbl
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@ -251,8 +251,8 @@ iteration can be performed more efficiently than plain
@interaction[
(let ((chapters '("Intro" "Details" "Conclusion")))
(for/vector (length chapters) ([i (in-naturals 1)]
[chapter chapters])
(for/vector #:length (length chapters) ([i (in-naturals 1)]
[chapter chapters])
(string-append (number->string i) ". " chapter)))
]

22
collects/scribblings/reference/for.scrbl
View File

@ -87,17 +87,19 @@ expression is a list of the results in order.
]}
@deftogether[(
@defform*[((for/vector (for-clause ...) body)
(for/vector length-expr (for-clause ...) body))]
@defform*[((for*/vector (for-clause ...) body)
(for*/vector length-expr (for-clause ...) body))])]{
@defform*[((for/vector (for-clause ...) body ...)
(for/vector #:length length-expr (for-clause ...) body ...))]
@defform*[((for*/vector (for-clause ...) body ...)
(for*/vector #:length length-expr (for-clause ...) body ...))])]{
Iterates like @scheme[for] or @scheme[for*], but the values of the
@scheme[body] expression are placed in a vector whose length is the
number of iterations. The optional @scheme[length-expr], if present,
is evaluated to determine the length of the vector in advance of the
iteration; if @scheme[length-expr] is provided, the computation is
more efficient.}
Iterates like @scheme[for] or @scheme[for*], but last expression in
the @scheme[body]s must produce a single value, which is placed in the
corresponding slot of a vector whose length is the number of
iterations. The optional @scheme[length-expr], if present, may allow
the computation to be performed more efficiently by pre-allocating a
vector of the given length. It is an error if evaluating the given
@scheme[length-expr] does not produce a valid length for a vector that
matches the number of iterations performed by the loop.}
@deftogether[(
@defform[(for/hash (for-clause ...) body ...+)]

8
collects/scribblings/reference/numbers.scrbl
View File

@ -1104,10 +1104,10 @@ elements of @scheme[v] efficiently as in @scheme[in-list],
@scheme[in-vector], etc.}
@deftogether[(
@defform*[((for/flvector (for-clause ...) body)
(for/flvector length-expr (for-clause ...) body))]
@defform*[((for*/flvector (for-clause ...) body)
(for*/flvector length-expr (for-clause ...) body))])]{
@defform*[((for/flvector (for-clause ...) body ...)
(for/flvector #:length length-expr (for-clause ...) body ...))]
@defform*[((for*/flvector (for-clause ...) body ...)
(for*/flvector #:length length-expr (for-clause ...) body ...))])]{
Like @scheme[for/vector] or @scheme[for*/vector], but for
@tech{flvector}s.}

20
collects/tests/racket/flonum.rktl
View File

@ -20,15 +20,31 @@
;; for/flvector test
(let ((flv (flvector 1.0 2.0 3.0))
(flv1 (for/flvector ((i (in-range 3))) (+ i 1.0)))
(flv2 (for/flvector 3 ((i (in-range 3))) (+ i 1.0))))
(flv2 (for/flvector #:length 3 ((i (in-range 3))) (+ i 1.0))))
(test flv 'for/flvector flv1)
(test flv 'for/flvector-fast flv2))
;; for*/flvector test
(let ((flv (flvector 0.0 0.0 0.0 0.0 1.0 2.0 0.0 2.0 4.0))
(flv1 (for*/flvector ((i (in-range 3)) (j (in-range 3))) (exact->inexact (* 1.0 i j))))
(flv2 (for*/flvector 9 ((i (in-range 3)) (j (in-range 3))) (exact->inexact (* 1.0 i j)))))
(flv2 (for*/flvector #:length 9 ((i (in-range 3)) (j (in-range 3))) (exact->inexact (* 1.0 i j)))))
(test flv 'for*/flvector flv1)
(test flv 'for*/flvector-fast flv2))
;; Test failure when too many iterations
(test #t 'for/vector-too-many-iters
(with-handlers ((exn:fail? (lambda (exn) #t)))
(for/flvector #:length 3 ((i (in-range 4))) (+ i 1.0))))
;; Test for many body expressions
(let* ((flv (flvector 1.0 2.0 3.0))
(flv2 (for/flvector ((i (in-range 3)))
(flvector-set! flv i (+ (flvector-ref flv i) 1.0))
(flvector-ref flv i)))
(flv3 (for/flvector #:length 3 ((i (in-range 3)))
(flvector-set! flv i (+ (flvector-ref flv i) 1.0))
(flvector-ref flv i))))
(test (flvector 2.0 3.0 4.0) 'for/flvector-many-body flv2)
(test (flvector 3.0 4.0 5.0) 'for/flvector-length-many-body flv3))
(report-errs)

24
collects/tests/racket/for.rktl
View File

@ -186,15 +186,33 @@
(list i j)))
(test '#(1 2 3 4) 'for/vector (for/vector ((i (in-range 4))) (+ i 1)))
(test '#(1 2 3 4) 'for/vector-fast (for/vector 4 ((i (in-range 4))) (+ i 1)))
(test '#(1 2 3 4) 'for/vector-fast (for/vector #:length 4 ((i (in-range 4))) (+ i 1)))
(test '#(0 0 0 0 1 2 0 2 4) 'for*/vector (for*/vector ((i (in-range 3))
(j (in-range 3)))
(+ i j)
(* i j)))
(test '#(0 0 0 0 1 2 0 2 4) 'for*/vector-fast (for*/vector 9 ((i (in-range 3))
(j (in-range 3)))
(test '#(0 0 0 0 1 2 0 2 4) 'for*/vector-fast (for*/vector #:length 9 ((i (in-range 3))
(j (in-range 3)))
(+ i j)
(* i j)))
;; Test failure when too many iterations
(test #t 'for/vector-too-many-iters
(with-handlers ((exn:fail? (lambda (exn) #t)))
(for/vector #:length 3 ((i (in-range 4))) (+ i 1.0))))
;; Test for many body expressions
(let* ((v (vector 1.0 2.0 3.0))
(v2 (for/vector ((i (in-range 3)))
(vector-set! v i (+ (vector-ref v i) 1.0))
(vector-ref v i)))
(v3 (for/vector #:length 3 ((i (in-range 3)))
(vector-set! v i (+ (vector-ref v i) 1.0))
(vector-ref v i))))
(test (vector 2.0 3.0 4.0) 'for/vector-many-body v2)
(test (vector 3.0 4.0 5.0) 'for/vector-length-many-body v3))
(test #hash((a . 1) (b . 2) (c . 3)) 'mk-hash
(for/hash ([v (in-naturals)]
[k '(a b c)])