#include <stdlib.h>
#include "c-stack.h"

struct stack_node {
	void* value;
	struct stack_node* next;
};

struct stack new_stack() { return (struct stack){ NULL }; /***/ }

void copy_stack(struct stack* s, const struct stack* t, void* (*copy)(const void*)) {
	struct stack_node** crnt = &s->head;
	for ( struct stack_node* next = t->head; next; next = next->next ) {
		*crnt = malloc(sizeof(struct stack_node)); /***/
		**crnt = (struct stack_node){ copy(next->value) }; /***/
		crnt = &(*crnt)->next;
	}
	*crnt = 0;
}

void clear_stack(struct stack* s, void (*free_el)(void*)) {
    for ( struct stack_node* next = s->head; next; ) {
		struct stack_node* crnt = next;
		next = crnt->next;
		free_el(crnt->value);
		free(crnt);
	}
	s->head = NULL;
}

_Bool stack_empty(const struct stack* s) { return s->head == NULL; }

void push_stack(struct stack* s, void* value) {
	struct stack_node* n = malloc(sizeof(struct stack_node)); /***/
	*n = (struct stack_node){ value, s->head }; /***/
	s->head = n;
}

void* pop_stack(struct stack* s) {
	struct stack_node* n = s->head;
	s->head = n->next;
	void* x = n->value;
	free(n);
	return x;
}