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// shared_ptr-examples.cpp
// based on https://docs.microsoft.com/en-us/cpp/cpp/how-to-create-and-use-shared-ptr-instances?view=msvc-160
#include <stc/cstr.h>
typedef struct
{
cstr artist;
cstr title;
} Song;
int Song_cmp(const Song* x, const Song* y)
{ return cstr_cmp(&x->title, &y->title); }
uint64_t Song_hash(const Song* x) { return cstr_hash(&x->title); }
Song Song_make(const char* artist, const char* title)
{ return (Song){cstr_from(artist), cstr_from(title)}; }
void Song_drop(Song* s) {
printf("drop: %s\n", cstr_str(&s->title));
c_drop(cstr, &s->artist, &s->title);
}
// Define the reference counted type
#define i_type SongArc
#define i_valclass Song
//#define i_opt c_no_hash
#include <stc/carc.h>
// ... and a vector of it
#define i_type SongVec
#define i_valboxed SongArc
#include <stc/cstack.h>
void example3()
{
c_auto (SongVec, vec1, vec2)
{
vec1 = c_make(SongVec, {
Song_make("Bob Dylan", "The Times They Are A Changing"),
Song_make("Aretha Franklin", "Bridge Over Troubled Water"),
Song_make("Thalia", "Entre El Mar y Una Estrella")
});
// Share all entries in vec with vec2, except Bob Dylan.
c_foreach (s, SongVec, vec1)
if (!cstr_equals(&s.ref->get->artist, "Bob Dylan"))
SongVec_push(&vec2, SongArc_clone(*s.ref));
// Add a few more to vec2. We can use emplace when creating new entries
SongVec_emplace(&vec2, Song_make("Michael Jackson", "Billie Jean"));
SongVec_emplace(&vec2, Song_make("Rihanna", "Stay"));
// If we use push, we would need to construct the Arc explicitly (as in c++, make_shared):
// SongVec_push(&vec2, SongArc_from(Song_make("Rihanna", "Stay")));
// We now have two vectors with some shared, some unique entries.
c_forlist (i, SongVec, {vec1, vec2}) {
puts("VEC:");
c_foreach (s, SongVec, *i.ref)
printf(" %s - %s, REFS: %ld\n", cstr_str(&s.ref->get->artist),
cstr_str(&s.ref->get->title),
*s.ref->use_count);
}
} // because the shared elem. are ref. counted, they are only dropped once here.
}
int main()
{
example3();
}
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