This is an idea I had for copying structures, mainly to make a
`record-copy' function (just an alias of struct-copy). I've found it
pretty useful.
You can do a record copy with `record-constructor' and a map over
`record-accessor' for each field, but of course a block copy is heaps
more efficient.
SCM_DEFINE_PUBLIC (struct_copy, "struct-copy", 1, 0, 0,
(SCM st),
"Return a copy of structure @var{st}. This is a shallow copy,\n"
"there's no recursive copying of the objects in the fields.")
#define FUNC_NAME s_struct_copy
{
scm_t_bits *vtable_data, *st_data, *new_st_data;
size_t n_words;
SCM_VALIDATE_STRUCT (SCM_ARG1, st);
vtable_data = SCM_STRUCT_VTABLE_DATA (st);
/* Only standard structs handled here, not goops entity or light forms.
Believe that's enough for ordinary public uses of structures as created
from `make-struct', `make-vtable', `make-vtable-vtable'. */
if (vtable_data[scm_struct_i_flags]
& (SCM_STRUCTF_ENTITY | SCM_STRUCTF_LIGHT))
SCM_WRONG_TYPE_ARG (SCM_ARG1, st);
st_data = SCM_STRUCT_DATA (st);
n_words = st_data[scm_struct_i_n_words];
new_st_data = scm_alloc_struct (n_words,
scm_struct_n_extra_words,
"struct");
memcpy (new_st_data, st_data, n_words * sizeof(scm_t_bits));
scm_remember_upto_here_1 (st);
return scm_double_cell ((scm_t_bits) vtable_data + scm_tc3_struct,
(scm_t_bits) new_st_data, 0, 0);
}
#undef FUNC_NAME
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