/*
 *                 GRAPH, Version 1.00 - 4 August 1989
 *
 *            Copyright 1989, David Gay. All Rights Reserved.
 *            This software is freely redistrubatable.
 */

/* class function, inherits from class object. The actual function types are su
b-classes of this one */
#ifndef FUNCTION_H
#define FUNCTION_H

#include "list.h"
#include "object.h"
#include "graph.h"
#include "user/eval.h"
#include <stddef.h>

#define MAXERROR 0.2 /* For discontinuities */
#define MAXITER 4    /* In improvement algo */
#define FLAT 2       /* number of pixels allowed in "flat" discontinuities */
#define DEFSTEPS 100 /* Default number of steps */
#define FDIST 5      /* Max (y) distance for function select */

/* class function (inherited from class object). Fields are public. */
struct function {
    struct object o;
    int (*calcf)(struct function *this, int allow_mes); /* Recalculate values o
f points */
    int (*save)(struct function *this, FILE *f);        /* Save function specif
ic info. to file */

    /* Information global to all types of functions */
    char vname[VARLEN]; /* name of variable */
    double min, max;    /* Limits for variable */
    int steps;          /* Number of points to calculate */
    BYTE colour;        /* Colour in which to draw */
    int showdisc : 1;   /* Show discontinuities ? */
    int nicedisc : 1;   /* Allow "nice" discontinuities */

    /* State info */
    int calc : 1;       /* Points calculated ? */
    int selected : 1;   /* function selected ? */
    variable var;       /* Actual variable */
    var_list used;      /* Vars this function depends on */
    list pts;           /* Points composing this, different structure for each
type of function */
    size_t sizept;      /* Size of one point (for delete) */
};

/* Flags for point state */
#define EXISTS 1  /* Function is defined here */
#define DISC 2    /* This is a discontinuity */
#define OK 4      /* All is well */

/* The base class for a point */
struct point {
    node node;
    char state;
    double x, y;
};

typedef struct point point;

/* Create/load the various types of function */
struct f_of_x *new_f_of_x(struct graph *g, char *name);
struct x_y *new_x_y(struct graph *g, char *name);
struct r_of_t *new_r_of_t(struct graph *g, char *name);
struct r_t *new_r_t(struct graph *g, char *name);
struct f_of_x *load_f_of_x(struct graph *g, FILE *f);
struct x_y *load_x_y(struct graph *g, FILE *f);
struct r_of_t *load_r_of_t(struct graph *g, FILE *f);
struct r_t *load_r_t(struct graph *g, FILE *f);

/* A few useful functions ... */
void display_function(struct function *this); /* Draws a function */
void init_function(struct function *this, struct graph *g, char *name); /* Stan
dard init. */
int load_rest(struct function *this, FILE *f); /* Load public part of function
*/

#endif