/* xlisp - a small subset of lisp */

/* system specific definitions */

/* DEFEXT	define to enable default extension of '.lsp' on 'load' */
/* FGETNAME	define if system supports 'fgetname' */
/* NNODES	number of nodes to allocate in each request */
/* TDEPTH	trace stack depth */
/* KEYMAPCLASS	define to include the 'Keymap' class */

/* for the VAX-11 C compiler */
#ifdef vms
#define DEFEXT
#define FGETNAME
#define KEYMAPCLASS
#define NNODES	2000
#define TDEPTH	1000
#endif

/* for the DECUS C compiler */
#ifdef decus
#define DEFEXT
#define KEYMAPCLASS
#define NNODES	200
#define TDEPTH	100
#endif

/* for unix compilers */
#ifdef unix
#define KEYMAPCLASS
#define NNODES	200
#define TDEPTH	100
#endif

/* for the AZTEC C compiler */
#ifdef AZTEC
#define DEFEXT
#define KEYMAPCLASS
#define NNODES	200
#define TDEPTH	100
#define getc(fp)	getch(fp)
#define kbin()		CPM(6,0xFF)
#define malloc		alloc
#define strchr		index
#endif

/* default important definitions */
#ifndef NNODES
#define NNODES	200
#endif
#ifndef TDEPTH
#define TDEPTH	100
#endif

/* useful definitions */
#define TRUE	1
#define FALSE	0

/* program limits */
#define STRMAX	100	/* maximum length of a string constant */

/* node types */
#define FREE	0
#define SUBR	1
#define LIST	2
#define SYM	3
#define INT	4
#define STR	5
#define OBJ	6
#define FPTR	7
#define KMAP	8

/* node flags */
#define MARK	1
#define LEFT	2

/* string types */
#define DYNAMIC	0
#define STATIC	1

/* symbol structure */
struct xsym {
    char *xsy_name;		/* symbol name */
    struct node *xsy_value;	/* the current value */
};

/* subr node structure */
struct xsubr {
    struct node *(*xsu_subr)();	/* pointer to an internal routine */
};

/* list node structure */
struct xlist {
    struct node *xl_value;	/* value at this node */
    struct node *xl_next;	/* next node */
};

/* integer node structure */
struct xint {
    int xi_int;			/* integer value */
};

/* string node structure */
struct xstr {
    int xst_type;		/* string type */
    char *xst_str;		/* string pointer */
};

/* object node structure */
struct xobj {
    struct node *xo_obclass;	/* class of object */
    struct node *xo_obdata;	/* instance data */
};

/* file pointer node structure */
struct xfptr {
    FILE *xf_fp;		/* the file pointer */
};

/* keymap structure */
struct xkmap {
    struct node *(*xkm_map)[];	/* selection pointer */
};


/* shorthand macros for accessing node substructures */

/* symbol node */
#define n_symname	n_info.n_xsym.xsy_name
#define n_symvalue	n_info.n_xsym.xsy_value

/* subr node */
#define n_subr		n_info.n_xsubr.xsu_subr

/* list node (and message node and binding node) */
#define n_listvalue	n_info.n_xlist.xl_value
#define n_listnext	n_info.n_xlist.xl_next
#define n_msg		n_info.n_xlist.xl_value
#define n_msgcode	n_info.n_xlist.xl_next
#define n_bndsym	n_info.n_xlist.xl_value
#define n_bndvalue	n_info.n_xlist.xl_next
#define n_left		n_info.n_xlist.xl_value
#define n_right		n_info.n_xlist.xl_next
#define n_ptr		n_info.n_xlist.xl_value

/* integer node */
#define n_int		n_info.n_xint.xi_int

/* string node */
#define n_str		n_info.n_xstr.xst_str
#define n_strtype	n_info.n_xstr.xst_type

/* object node */
#define n_obclass	n_info.n_xobj.xo_obclass
#define n_obdata	n_info.n_xobj.xo_obdata

/* file pointer node */
#define n_fname		n_info.n_xfptr.xf_name
#define n_fp		n_info.n_xfptr.xf_fp

/* key map node */
#define n_kmap		n_info.n_xkmap.xkm_map

/* node structure */
struct node {
    char n_type;		/* type of node */
    char n_flags;		/* flag bits */
    union {			/* value */
	struct xsym n_xsym;	/*     symbol node */
	struct xsubr n_xsubr;	/*     subr node */
	struct xlist n_xlist;	/*     list node */
	struct xint n_xint;	/*     integer node */
	struct xstr n_xstr;	/*     string node */
	struct xobj n_xobj;	/*     object node */
	struct xfptr n_xfptr;	/*     file pointer node */
	struct xkmap n_xkmap;	/*     key map node */
    } n_info;
};

/* external procedure declarations */
extern struct node *xlread();		/* read an expression */
extern struct node *xleval();		/* evaluate an expression */
extern struct node *xlarg();		/* fetch an argument */
extern struct node *xlevarg();		/* fetch and evaluate an argument */
extern struct node *xlmatch();		/* fetch an typed argument */
extern struct node *xlevmatch();	/* fetch and evaluate a typed arg */
extern struct node *xlsend();		/* send a message to an object */
extern struct node *xlmfind();		/* find the method for a message */
extern struct node *xlxsend();		/* execute a message method */
extern struct node *xlenter();		/* enter a symbol into the oblist */
extern struct node *xlsave();		/* generate a stack frame */
extern struct node *xlobsym();		/* find an object's class or instance
					   variable */
extern struct node *xlclass();		/* enter a class definition */
extern struct node *xlivar();		/* get an instance variable */
extern struct node *xlcvar();		/* get an instance variable */
extern struct node *newnode();		/* allocate a new node */

extern char *stralloc();		/* allocate string space */
extern char *strsave();			/* make a safe copy of a string */