#ifndef _PLY_NODE_H
#define _PLY_NODE_H

#include <stdint.h>
#include <stdio.h>

struct sym;
/* symbol information is defined externally */

enum ntype {
	N_EXPR,
	N_IDENT,
	N_NUM,
	N_STRING,
};

struct node {
	struct node *next, *prev, *up;

	struct sym *sym;

	enum ntype ntype;

	union {
		struct {
			char *func;
			struct node *args;
		} expr;
		struct {
			char *name;
		} ident;
		struct {
			int64_t num;
		} num;
		struct {
			char *data;
		} string;
	};
};

/* debug */
void node_print(struct node *n, FILE *fp);

typedef int (*nwalk_fn)(struct node *, void *);
int node_walk(struct node *n, nwalk_fn pre, nwalk_fn post, void *ctx);

int node_replace(struct node *n, struct node *new);


/* constructors */
struct node *node_string(char *data);
struct node *node_num   (int64_t num);
struct node *node_ident (char *name);
struct node *node_append(struct node *n, struct node *arg);
struct node *node_expr  (char *func, ...);


/* helpers */

static inline int node_nargs(struct node *n)
{
	struct node *arg;
	int nargs = 0;

	for (arg = n->expr.args; arg; arg = arg->next, nargs++);

	return nargs;
}

int node_is_block(struct node *n);
int node_is_map  (struct node *n);

#define node_expr_foreach(_expr, _arg) \
	for ((_arg) = (_expr)->expr.args; (_arg); (_arg) = (_arg)->next)

#endif	/* _PLY_NODE_H */