generalize `flvector-copy' to support start and end indices

collects/racket/flonum.rkt

@@ -86,7 +86,27 @@
              (add1 i))
            v))))))
 
-(define (flvector-copy flv)
-  (for/flvector #:length (flvector-length flv)
-                ((x (in-flvector flv)))
-                x))
+(define (flvector-copy flv [start 0] [end (and (flvector? flv) (flvector-length flv))])
+  (unless (flvector? flv)
+    (raise-type-error 'flvector-copy "flvector" flv))
+  (unless (exact-nonnegative-integer? start)
+    (raise-type-error 'flvector-copy "non-negative exact integer" start))
+  (unless (exact-nonnegative-integer? end)
+    (raise-type-error 'flvector-copy "non-negative exact integer" end))
+  (let ([orig-len (flvector-length flv)])
+    (unless (<= start end orig-len)
+      (unless (<= start orig-len)
+        (raise-mismatch-error 'flvector-copy 
+                              (format "start index ~s out of range [~a, ~a] for flvector: "
+                                      start 0 orig-len)
+                              flv))
+      (raise-mismatch-error 'flvector-copy 
+                            (format "end index ~s out of range [~a, ~a] for flvector: "
+                                    end start orig-len)
+                            flv)))
+  (let* ([len (- end start)]
+         [vec (make-flvector len)])
+    (for ([i (in-range len)])
+      (flvector-set! vec i (flvector-ref flv (+ i start))))
+    vec))
+

collects/racket/vector.rkt

@@ -27,7 +27,7 @@
   (unless (vector? v)
     (raise-type-error 'vector-copy "vector" v))
   (unless (exact-nonnegative-integer? start)
-    (raise-type-error 'vector-copy "non-negative exact integer" 1 start))
+    (raise-type-error 'vector-copy "non-negative exact integer" start))
   (let ([len (vector-length v)])
     (cond
       [(= len 0)

collects/scribblings/reference/numbers.scrbl

@@ -1096,9 +1096,16 @@ Sets the inexact real number in slot @racket[pos] of @racket[vec]. The
 first slot is position @racket[0], and the last slot is one less than
 @racket[(flvector-length vec)].}
 
-@defproc[(flvector-copy (v flvector?)) flvector?]{
+@defproc[(flvector-copy [vec flvector?]
+                        [start exact-nonnegative-integer? 0]
+                        [end exact-nonnegative-integer? (vector-length v)]) 
+         flvector?]{
 
-Returns a fresh copy of @racket[v].}
+Creates a fresh @tech{flvector} of size @racket[(- end start)], with all of the
+elements of @racket[vec] from @racket[start] (inclusive) to
+@racket[end] (exclusive).
+
+Returns a fresh copy of @racket[vec].}
 
 @defproc[(in-flvector (v flvector?)) sequence?]{
 

collects/scribblings/reference/vectors.scrbl

@@ -262,8 +262,11 @@ except that it can be faster.
 ]}
 
 
-@defproc[(vector-copy [vec vector?] [start exact-nonnegative-integer?
-0] [end exact-nonnegative-integer? (vector-length v)]) vector?]{
+@defproc[(vector-copy [vec vector?] 
+                      [start exact-nonnegative-integer? 0]
+                      [end exact-nonnegative-integer? (vector-length v)]) 
+         vector?]{
+
 Creates a fresh vector of size @racket[(- end start)], with all of the
 elements of @racket[vec] from @racket[start] (inclusive) to
 @racket[end] (exclusive).

collects/tests/racket/flonum.rktl

@@ -2,7 +2,7 @@
 
 (Section 'flonum)
 
-(require scheme/flonum)
+(require racket/flonum)
 
 (define (flonum-close? fl1 fl2)
   (<= (flabs (fl- fl1 fl2))
@@ -70,6 +70,8 @@
       (test vx 'flvector-copy vcx))
     (flvector-set! vc 2 -10.0)
     (test 2.0 'flvector-copy (flvector-ref v 2))
-    (test -10.0 'flvector-copy (flvector-ref vc 2))))
+    (test -10.0 'flvector-copy (flvector-ref vc 2))
+    (test '(2.0 3.0) 'flvector-copy (for/list ([i (in-flvector (flvector-copy v 2))]) i))
+    (test '(2.0) 'flvector-copy (for/list ([i (in-flvector (flvector-copy v 2 3))]) i))))
 
 (report-errs)