#ifndef EXPR_H
#define EXPR_H

#define MAX_SYMBOL_LEN 32U

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

struct am;
struct store;

typedef struct {
	char buf[MAX_SYMBOL_LEN];
	size_t len;
} symbol_t;

typedef void (*prim_proc_t)(struct am *am, struct store *store);

typedef enum {
	ATOM_TYPE_EMPTY_LIST,
	ATOM_TYPE_INTEGER,
	ATOM_TYPE_SYMBOL,
	ATOM_TYPE_PRIM_PROC,
} atom_type_t;

typedef struct {
	atom_type_t type;
	union {
		int64_t integer;
		symbol_t symbol;
		prim_proc_t prim_proc;
	};
} atom_t;

struct expr;

typedef struct {
	struct expr *car, *cdr;
} pair_t;

typedef struct expr {
	bool is_atom;
	union {
		atom_t atom;
		pair_t pair;
	};
} expr_t;

expr_t *expr_integer(struct store *store, int64_t value);
expr_t *expr_symbol(struct store *store, const symbol_t *symbol);
expr_t *expr_str_symbol(struct store *store, const char *str);
expr_t *expr_empty_list(struct store *store);
expr_t *expr_pair(struct store *store, expr_t *car, expr_t *cdr);
expr_t *expr_prim_proc(struct store *store, prim_proc_t prim_proc);

#endif