src/lisp/lisp.h

#pragma once

#include <stdbool.h>
#include <stdio.h>

enum type
{
	T_INT = 0,
	T_FLOAT,
	T_NIL,
	T_SYMBOL,
	T_STRING,
	T_VECTOR,
	T_CLASS,
	T_CONS,
};

#define INT_MASK 0b11
#define INT_TAG 0b00

#define CHAR_MASK 0xff
#define CHAR_TAG 0b00001111

#define BOOL_MASK 0b1111111
#define BOOL_TAG 0b0011111

#define HEAP_MASK 0b111

#define CONS_TAG 0b001
#define VECTOR_TAG 0b010
#define STRING_TAG 0b011
#define SYMBOL_TAG 0b101
#define CLOSURE_TAG 0b110

struct cons;

typedef unsigned int value_t;

struct cons
{
	int magic;
	int marked; // must be reserved
	value_t car, cdr;
};

struct alloc_list
{
	int type;
	union {
		struct cons *cons_val;
	};
	struct alloc_list *next, *prev;
};

struct istream
{
	void *data;

	// These two return -1 on error
	int (*peek) (struct istream *s);
	int (*get) (struct istream *s);

	int (*read) (struct istream *s, char *buffer, int size);

	void (*showpos) (struct istream *s, FILE *out);
};

bool startswith (struct istream *s, char *pattern);

bool readsym (struct istream *is, value_t *val);
bool readstr (struct istream *is, value_t *val);
bool readlist (struct istream *is, value_t *val);
bool readint (struct istream *is, value_t *val);

value_t intval (int i);
value_t strval (char *str);
value_t cons (value_t car, value_t cdr);
bool read1 (struct istream *is, value_t *val);
value_t read (struct istream *is);
value_t readn (struct istream *is);

value_t car (value_t v);
value_t cdr (value_t v);
value_t *carref (value_t v);
value_t *cdrref (value_t v);

bool integerp (value_t v);
bool symbolp (value_t v);
bool stringp (value_t v);
bool consp (value_t v);
bool listp (value_t v);
bool nilp (value_t v);
int length (value_t v);
value_t elt (value_t v, int index);

void printval (value_t v, int depth);

struct istream *new_stristream (char *str, int length);
// same as above but null terminated
struct istream *new_stristream_nt (char *str);
void del_stristream (struct istream *stristream);

void err (const char *msg);

extern value_t nil;

#define FOREACH(item, list)                                                    \
	for ( ; listp (list); )                                                    \
		for ( value_t item = car (list), _foreach_current = list;              \
		      !nilp (_foreach_current);                                        \
		      _foreach_current = cdr (_foreach_current),                       \
		              item = car (_foreach_current) )