Calculator/calculator.cpp

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "calculator.h"

double str_to_double (const char * str) {
  return strtod (str, NULL);
}
long str_to_long (const char * str) {
  return strtol (str, NULL, 10);
}

static double u_minus (const double x) { return -x; }
const unary_function unary_function_table [UNARY_max] = {
  u_minus,
  sin, cos, exp, log,
};
static double b_plus     (const double a, const double b) { return a + b; }
static double b_minus    (const double a, const double b) { return a - b; }
static double b_multiply (const double a, const double b) { return a * b; }
static double b_divide   (const double a, const double b) { return b !=0.0 ? a / b : 1.0; }
const binary_function binary_function_table [BINARY_max] = {
  b_plus, b_minus, b_multiply, b_divide, pow,
};
static CommonData * main_data = nullptr;
void addVariable (const char * str, const double x) {
  printf ("\"%s\"\t= %g\n", str, x);
  if (main_data->list == nullptr) {
    main_data->list = new VariableList (str, x);
    return;
  }
  main_data->list->add(str, x);
}
void addRange (const char * str, const double x, const double e, const double s) {
  printf ("\"%s\"\t= [%g:%g],%g\n", str, x, e, s);
  if (main_data->list == nullptr) {
    main_data->list = new VariableList (str, x, e, s);
    return;
  }
  main_data->list->add(str, x, e, s);
}
static Range zero = {0.0, 0.0, 0.0};
Variable::Variable(const char * name) {
  data = main_data->list->find (name);
  if (!data) {
    printf("variable \"%s\" not assigned, zero used\n", name);
    data = & zero;
  }
}
static bool first = false;
extern void emitData (double * x, double * y, const int len, const bool first);
void addExpression (Expression * e) {
  if (main_data->root) delete main_data->root;
  main_data->root = e;
  
  VariableList * vl = main_data->list->find_ranged();
  if (!vl) {
    printf("f() = %g\n", e->eval());    
    return;
  }
  Range * r = vl->get();
  const double x0 = r->value, x1 = r->end, s = fabs (r->step);
  int n = (x1 - x0) / s;
  if (n <= 0) return;
  double * vx = new double [n + 1];
  double * vy = new double [n + 1];
  for (int i=0; i<n+1; i++) {
    const double x = x0 + (double) i * s;
    r->value = x;
    const double y = e->eval();
    vx[i] = x; vy[i] = y;
  }
  r->value = x0;
  // printf("add expression first=%d, n=%d\n", (int) first, n);
  emitData (vx, vy, n+1, first);
  if (first) first = false;
  delete [] vx; delete [] vy;
}
void initData () {
  first = true;
  main_data = new CommonData();
}
void finiData () {
  delete main_data;
}