/* Internal structures */
#include <exec/types.h>
#include <exec/nodes.h>
#include <exec/lists.h>

#include "eval.h"
#include "memory.h"
#include "pattern.h"
#include "subst.h"

/* How expressions are stored */
typedef double (*FUNCTION)(double);
typedef enum {plus, minus, times, divide, power, opsize} e_op;

typedef struct {
    FUNCTION func;
    value arg;
} function;

typedef struct {
    e_op op;
    value arg1, arg2;
} operator;

struct _value {
    enum {cste, var, fonc, op} type;
    union {
	double c;
	variable v;
	function f;
	operator o;
    } contents;
};

/* A few defines to simplify access */
#define vr contents.v
#define fn contents.f
#define opr contents.o
#define cte contents.c

/* Table for stroring recognised functions */
typedef struct {
    FUNCTION func;
    char *functext;
} onefunc;

/* The tables of simplifications ... */
extern subst *simp[], *derv[];

onefunc *locate(FUNCTION);                      /* Find name of function from address */
onefunc *locate_name(char *);                   /* Find address of function from name */
double check_fp(double, double, double, char *);/* Map exceptions for /+-* to those used by math functions */
value _eval(value, int);                        /* Evaluate an expression(internal version) */