/******************************************************************************
 *
 * 9998sketch/expr.h
 *
 * (c) Eugene K. Ressler, Jr. 2004, 2005
 *
 * A program related to the book
 *
 * Fundamentals of Virtual World Simulation
 * by Eugene K. Ressler, Jr.
 *
 * No warranty of correctness or capability of any kind is expressed or implied.
 *
 * The author grants free use of this code for any purpose as long any text,
 * executable program, library file, or source code distributed to others 
 * and employing any portion of this code clearly cites the book named above.
 *
 ******************************************************************************/

#ifndef __EXPR_H
#define __EXPR_H

#include <stdio.h>
#include "geometry.h"

// used by parser for dynamically typed expression evaluation
// must match expr_val_type_str[] in expr.c
typedef enum expr_typa_t {
  E_FLOAT,
  E_POINT,
  E_VECTOR,
  E_TRANSFORM,
} EXPR_TYPE;

extern char *expr_val_type_str[];

typedef struct expr_val_t {
  EXPR_TYPE tag;
  union {
    FLOAT flt;
    POINT_3D pt;
    VECTOR_3D vec;
    TRANSFORM xf;
  } val;
} EXPR_VAL;

#define EXPR_TYPE_IS(E, T)  ((E)->tag == (T))

// set expression value to given type and value
void set_float(EXPR_VAL *r, FLOAT val);
void set_point(EXPR_VAL *r, POINT_3D val);
void set_vector(EXPR_VAL *r, VECTOR_3D val);
void set_transform(EXPR_VAL *r, TRANSFORM val);

// coerce an expression value to given type 
// generate error message if it can't be done
void coerce_to_float(EXPR_VAL *r, FLOAT *val, SRC_LINE line);
void coerce_to_point(EXPR_VAL *r, POINT_3D val, SRC_LINE line);
void coerce_to_vector(EXPR_VAL *r, VECTOR_3D val, SRC_LINE line);
void coerce_to_transform(EXPR_VAL *r, TRANSFORM val, SRC_LINE line);

void print_expr_val(FILE *f, EXPR_VAL *r);

void do_add(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_sub(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_mul(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_thn(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_dvd(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_dot(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_pwr(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_mag(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_neg(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_unit(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_sqrt(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_sin(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_cos(EXPR_VAL *r, EXPR_VAL *a, SRC_LINE line);
void do_index(EXPR_VAL *r, EXPR_VAL *a, int index, SRC_LINE line);
void do_atan2(EXPR_VAL *r, EXPR_VAL *a, EXPR_VAL *b, SRC_LINE line);
void do_inverse(TRANSFORM inv, TRANSFORM xf, SRC_LINE line);

#endif