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// Implements c++ example: https://en.cppreference.com/w/cpp/container/priority_queue
// Example of per-instance less-function on a single priority queue type
//
// Note: i_less_functor: available for cpque types
// i_cmp_functor: available for csmap and csset types
// i_hash_functor/i_eq_functor: available for cmap and cset types
#include <stdio.h>
#include <stdbool.h>
#include <stc/forward.h>
#include <stc/views.h>
#include <stc/cstr.h>
// predeclare
forward_cpque(ipque, int);
struct {
ipque Q;
bool (*less)(const int*, const int*);
} typedef IPQueue;
#define IPQueue_drop(q) ipque_drop(&(q)->Q)
#define i_type ipque
#define i_val int
#define i_opt c_is_forward // needed to avoid re-type-define container type
#define i_less_functor(self, x, y) c_container_of(self, IPQueue, Q)->less(x, y) // <== This.
#include <stc/cpque.h>
#define print(name, q, n) do { \
printf("%s: \t", name); \
c_forrange (i, n) printf("%d ", q[i]); \
puts(""); \
} while(0)
void print_queue(const char* name, IPQueue q) {
// NB: make a clone because there is no way to traverse
// priority_queue's content without erasing the queue.
IPQueue copy = {ipque_clone(q.Q), q.less};
for (printf("%s: \t", name); !ipque_empty(©.Q); ipque_pop(©.Q))
printf("%d ", *ipque_top(©.Q));
puts("");
ipque_drop(©.Q);
}
static bool int_less(const int* x, const int* y) { return *x < *y; }
static bool int_greater(const int* x, const int* y) { return *x > *y; }
static bool int_lambda(const int* x, const int* y) { return (*x ^ 1) < (*y ^ 1); }
int main()
{
const int data[] = {1,8,5,6,3,4,0,9,7,2}, n = c_arraylen(data);
print("data", data, n);
c_autodrop (IPQueue, q1, {ipque_init(), int_less}) // Max priority queue
c_autodrop (IPQueue, minq1, {ipque_init(), int_greater}) // Min priority queue
c_autodrop (IPQueue, q5, {ipque_init(), int_lambda}) // Using lambda to compare elements.
{
c_forrange (i, n)
ipque_push(&q1.Q, data[i]);
print_queue("q1", q1);
c_forrange (i, n)
ipque_push(&minq1.Q, data[i]);
print_queue("minq1", minq1);
c_forrange (i, n)
ipque_push(&q5.Q, data[i]);
print_queue("q5", q5);
}
}
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