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Also SUBSEQ and FILL! [was Re: additional operations: COPY! and COPY]
On Mon, 14 Mar 2005 sebastian.egner@xxxxxxxxxxx wrote:
> Then I would like to support and Taylor's proposal of having a COPY!
> operation, for example with the following specification:
> (BYTE-VECTOR-COPY! lhs i-lhs rhs i-rhs n)
> copies n bytes from the byte-vector rhs (starting at index i-rhs)
> the byte-vector lhs (starting at index i-lhs). The exact integers
> n, i-rhs,
> and i-lhs satisfy
> 0 <= i-rhs <= i-rhs + n <= (byte-vector-length rhs),
> 0 <= i-lhs <= i-lhs + n <= (byte-vector-length lhs).
> The procedure makes sure the elements are properly copied, even if
> lhs and rhs refer to the same byte-vector object.
> (Warning to implementors in C: Use memmove, not memcpy!)
> In addition, I am frequently missing VECTOR-COPY, and this will likely
> also be the case for byte vectors. So I propose to include also:
> (BYTE-VECTOR-COPY byte-vector)
I'd like to suggest generalizing this to something like:
(BYTE-VECTOR-SUBSEQUENCE byte-vector [start-offset [end-offset]])
or maybe just adding:
(BYTE-VECTOR-SUBSEQUENCE byte-vector start-offset [end-offset])
which granted is implemented in two lines with a CREATE and a COPY!, but
neverthess I find it a quite common operation worthy of a common name.
> Concerning the /fill/ argument in MAKE-BYTE-VECTOR: It is optional in
> R5RS, but I would be in favour of having it mandatory here.
I would like to additionally suggest:
(BYTE-VECTOR-FILL! byte-vector start-offset end-offset(or length?) value)
for the many times I find myself needing to fill just a portion of a byte
-- Donovan Kolbly ( d.kolbly@xxxxxxxxxxx