From: "René Scharfe" <l.s.r@web.de>
To: Git List <git@vger.kernel.org>
Cc: Junio C Hamano <gitster@pobox.com>
Subject: [PATCH v2 3/4] add DUP_ARRAY
Date: Sun, 1 Jan 2023 22:14:12 +0100 [thread overview]
Message-ID: <04e99a14-a25b-7e47-8bf3-49442c877c89@web.de> (raw)
In-Reply-To: <9bc1bd74-f72c-1b43-df7c-950815babb03@web.de>
Add a macro for allocating and populating a shallow copy of an array.
It is intended to replace a sequence like this:
ALLOC_ARRAY(dst, n);
COPY_ARRAY(dst, src, n);
With the less repetitve:
DUP_ARRAY(dst, src, n);
It checks whether the types of source and destination are compatible to
ensure the copy can be used safely.
An easier alternative would be to only consider the source and return
a void pointer, that could be used like this:
dst = ARRAY_DUP(src, n);
That would be more versatile, as it could be used in declarations as
well. Making it type-safe would require the use of typeof_unqual from
C23, though.
So use the safe and compatible variant for now.
Signed-off-by: René Scharfe <l.s.r@web.de>
---
Why typeof_unqual and not just typeof? To remove const when duplicating
a const array.
git-compat-util.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/git-compat-util.h b/git-compat-util.h
index e81bb14fc9..44abb240ae 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1115,6 +1115,11 @@ static inline void move_array(void *dst, const void *src, size_t n, size_t size)
memmove(dst, src, st_mult(size, n));
}
+#define DUP_ARRAY(dst, src, n) do { \
+ size_t dup_array_n_ = (n); \
+ COPY_ARRAY(ALLOC_ARRAY((dst), dup_array_n_), (src), dup_array_n_); \
+} while (0)
+
/*
* These functions help you allocate structs with flex arrays, and copy
* the data directly into the array. For example, if you had:
--
2.39.0
next prev parent reply other threads:[~2023-01-01 21:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-30 21:51 [PATCH 0/3] COPY_ARRAY, MOVE_ARRAY, DUP_ARRAY René Scharfe
2022-12-30 21:56 ` [PATCH 1/3] do full type check in COPY_ARRAY and MOVE_ARRAY René Scharfe
2023-01-01 3:03 ` Junio C Hamano
2023-01-01 3:59 ` Junio C Hamano
2023-01-01 7:41 ` René Scharfe
2023-01-01 10:45 ` René Scharfe
2023-01-01 12:11 ` Junio C Hamano
2023-01-01 12:32 ` René Scharfe
2023-01-01 12:46 ` Junio C Hamano
2022-12-30 22:02 ` [PATCH 2/3] add DUP_ARRAY René Scharfe
2022-12-30 22:03 ` [PATCH 3/3] use DUP_ARRAY René Scharfe
2023-01-01 21:05 ` [PATCH v2 0/4] COPY_ARRAY, MOVE_ARRAY, DUP_ARRAY René Scharfe
2023-01-01 21:08 ` [PATCH v2 1/4] factor out BARF_UNLESS_COPYABLE René Scharfe
2023-01-01 21:11 ` [PATCH v2 2/4] do full type check in BARF_UNLESS_COPYABLE René Scharfe
2023-01-08 7:28 ` Junio C Hamano
2023-01-08 10:10 ` René Scharfe
2023-01-09 4:27 ` Junio C Hamano
2023-01-09 18:08 ` Jeff Hostetler
2023-01-01 21:14 ` René Scharfe [this message]
2023-01-01 21:16 ` [PATCH v2 4/4] use DUP_ARRAY René Scharfe
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