function_test.cpp

/****************************************************************************
**  Copyright (c) 2023, Adel Kara Slimane <adel.ks@zegrapher.com>
**
**  This file is part of ZeCalculator.
**
**  ZeCalculators is free software: you may copy, redistribute and/or modify it
**  under the terms of the GNU Affero General Public License as published by the
**  Free Software Foundation, either version 3 of the License, or (at your
**  option) any later version.
**
**  This file is distributed in the hope that it will be useful, but
**  WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
**  General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program.  If not, see <http://www.gnu.org/licenses/>.
**
****************************************************************************/

#include <zecalculator/zecalculator.h>

// testing specific headers
#include <boost/ut.hpp>
#include <zecalculator/test-utils/print-utils.h>
#include <zecalculator/test-utils/structs.h>
#include <zecalculator/test-utils/utils.h>

#include <numbers>

using namespace zc;
using namespace std::literals;

int main()
{
  using namespace boost::ut;

  "multi-parameter function evaluation"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;
    auto& f = world.new_object() = "f(omega,t) = cos(omega * t) + omega * t";

    expect(f.get_input_var_names() == std::vector{"omega"s, "t"s});

    const double omega = 2;
    const double t = 3;

    // note: the order of the arguments is important
    const double res = f({omega, t}).value();
    const double expected_res = std::cos(omega * t) + omega * t;

    expect(res == expected_res);

    // dynamic object tests
    auto* obj = world.get("f");
    expect(obj && (*obj)({omega, t}).value() == expected_res);

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function whose expression is a number"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;
    auto& f = world.new_object() = "f(x) = 0.5";

    expect(bool(f));
    expect(f.holds(ObjectType::FUNCTION));
    expect(f({3.0}).value() == 0.5);

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function evaluation shadowing a global constant"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;
    world.new_object() = "x = 2.0";
    auto& f = world.new_object() = "f(x) = cos(x) + x";

    expect(f.get_input_var_names() == std::vector{"x"s});

    const double res = f({1.0}).value();
    const double expected_res = std::cos(1.0) + 1.0;

    expect(res == expected_res);

    // dynamic object tests
    auto* x_obj = world.get("x");
    expect(x_obj && (*x_obj)().value() == 2.0);

    auto* f_obj = world.get("f");
    expect(f_obj && (*f_obj)({1.0}).value() == expected_res);

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function calling another function"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;
    auto& f1 = world.new_object();
    auto& f2 = world.new_object();

    f2 = "f2(x) = cos(x) + 2*x^2";
    f1 = "f1(x) = cos(x) + x + f2(2*x)";

    expect(f1.get_input_var_names() == std::vector{"x"s});
    expect(f2.get_input_var_names() == std::vector{"x"s});

    expect(bool(f1));
    expect(bool(f2));

    auto cpp_f2 = [](double x)
    {
      return std::cos(x) + 2*x*x;
    };
    auto cpp_f1 = [cpp_f2](double x)
    {
      return std::cos(x) + x + cpp_f2(2*x);
    };

    double x = 6.4;

    const auto expected_res2 = f2({2*x});

    const bool res2_status = bool(expected_res2);

    expect(res2_status);

    using namespace boost::ut::literals;

    if (res2_status)
      expect(expected_res2.value() - cpp_f2(2*x) == 0.0_d);

    const auto expected_res1 = f1({x});

    expect(bool(expected_res1));

    if (bool(expected_res1))
      expect(std::fabs(expected_res1.value() - cpp_f1(x)) < 1e-11) << expected_res1.value() << " = " << cpp_f1(x);
  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function overwrites"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    auto& cst = world.new_object() = "my_constant = 3.0";
    auto& f = world.new_object() = "f(x) = x + my_constant + cos(math::pi)";

    auto* f_obj = world.get("f");
    expect(f_obj);

    double cpp_cst = 3.0;
    auto cpp_f_1 = [&](double x)
    {
      return x + cpp_cst + std::cos(std::numbers::pi);
    };

    expect(f({1}).value() == cpp_f_1(1.0));
    expect((*f_obj)({1}) == cpp_f_1(1.0));

    cst = 5.0;
    cpp_cst = 5.0;

    expect(f({1}).value() == cpp_f_1(1.0));
    expect((*f_obj)({1}).value() == cpp_f_1(1.0));

    world.new_object() = "g(z) = 2*z + my_constant";

    // override expression and variable name of f
    f = "f(y) = y + my_constant + g(y)";

    auto cpp_g = [&](double z)
    {
      return 2*z + cpp_cst;
    };

    auto cpp_f_2 = [&](double y)
    {
      return y + cpp_cst + cpp_g(y);
    };

    expect(f({3}).value() == cpp_f_2(3));
    expect((*f_obj)({3}).value() == cpp_f_2(3));

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "nested multi-variable functions"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    world.new_object() = "h(c,d) = c*d + c-d";
    world.new_object() = "g(a,b) = h(a, a*b) + 3*a - b";
    auto& f = world.new_object() = "f(x, y) = h(x, g(x, y)) + g(y, h(y, x))";

    expect(world.get("h")->get_input_var_names() == std::vector{"c"s, "d"s});
    expect(world.get("g")->get_input_var_names() == std::vector{"a"s, "b"s});
    expect(f.get_input_var_names() == std::vector{"x"s, "y"s});

    auto cpp_h = [](double c, double d) {
      return c*d + c-d;
    };

    auto cpp_g = [&](double a, double b) {
      return cpp_h(a, a*b) + 3*a - b;    };

    auto cpp_f = [&](double x, double y) {
      return cpp_h(x, cpp_g(x, y)) + cpp_g(y, cpp_h(y, x));
    };

    const double x = 5, y = 3;

    expect(f({x, y}).value() == cpp_f(x, y));

    auto* f_obj = world.get("f");
    expect(f_obj && (*f_obj)({x, y}).value() == cpp_f(x, y));

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function with dot in name"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    // add a function named "f", note that the constant "my_constant" is only defined after
    auto& fx = world.new_object() = "f.x(x) = 1 + x";
    auto& fy = world.new_object() = "f.y = 2.0 + f.x(1)";

    expect(fx({1}).value() == 2.0);
    expect(fy().value() == 4.0);

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "calling function with wrong number of arguments"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    // add a function named "f", note that the constant "my_constant" is only defined after
    world.new_object() = "f(x, y) = 1 + x + y";

    std::string var_expr = "1 + f(1, 2, 3)";
    std::expected<double, Error> res = world.evaluate(var_expr);

    expect(not res.has_value());
    expect(res.error() == Error::mismatched_fun_args(parsing::tokens::Text{"1, 2, 3", 6}, var_expr))
      << res.error();

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "multi variable function"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    // add a function named "f", note that the constant "my_constant" is only defined after
    auto& f = world.new_object() = "f(u, v, w, x, y, z) = 1 + u + v + w + x + y + z";

    expect(f.get_input_var_names() == std::vector{"u"s, "v"s, "w"s, "x"s, "y"s, "z"s});

    expect(f.has_value()) << fatal;

    auto res = f({1, 1, 1, 1, 1, 1});
    expect(bool(res)) << fatal;
    expect(res.value() == 7_i);

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function benchmark"_test = []<class StructType>()
  {
    constexpr auto duration = nanoseconds(500ms);
    {
      constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;
      constexpr std::string_view data_type_str_v = std::is_same_v<StructType, FAST_TEST> ? "FAST" : "RPN";

      MathWorld<type> world;
      auto& f = (world.new_object() = "f(x) =3*cos(3*x) + 2*sin(x/2) + 4");

      double x = 0;
      double res = 0;
      size_t iterations =
        loop_call_for(duration, [&]{
          res += f({x}).value();
          x++;
      });
      std::cout << "Avg zc::Function<" << data_type_str_v << "> eval time: "
                << duration_cast<nanoseconds>(duration / iterations).count() << "ns"
                << std::endl;
      std::cout << "dummy val: " << res << std::endl;
    }
    {
      auto cpp_f = [](double x) {
        return 3*cos(3.*x) + 2*sin(x/2.) + 4;
      };

      double x = 0;
      double res = 0;
      size_t iterations =
        loop_call_for(duration, [&]{
          res += cpp_f(x);
          iterations++;
          x++;
      });
      std::cout << "Avg C++ function eval time: " << duration_cast<nanoseconds>(duration/iterations).count() << "ns" << std::endl;
      std::cout << "dummy val: " << res << std::endl;

    }

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "sequence direct dependencies"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    // add a function named "f", note that the constant "my_constant" is only defined after
    world.new_object() = "f(x, y) = 1 + x + y";
    auto& seq = world.new_object() = "u(n) = 0 ; 1 + f(1, 1) + f(2, 2) + u(n-1) + 3*u(n-1) + cos(n)";

    constexpr auto t = Dep::FUNCTION;
    expect(seq.direct_dependencies()
           == Deps{{"u", {t}}, {"f", {t}}, {"cos", {t}}});

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "function direct dependencies"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    // add a function named "f", note that the constant "my_constant" is only defined after
    world.new_object() = "my_constant = 3.0";
    auto& f = world.new_object() = "f( x)  = x + my_constant + cos(math::pi)";

    expect(world.get("my_constant")->get_input_var_names().empty());

    using namespace std::string_literals;

    expect(f.direct_dependencies()
           == Deps{{"my_constant", {Dep::VARIABLE}},
                         {"cos", {Dep::FUNCTION}},
                         {"math::pi", {Dep::VARIABLE}}}); // "u" and "f"

  } | std::tuple<FAST_TEST, RPN_TEST>{};

  "name of function in error state"_test = []<class StructType>()
  {
    constexpr parsing::Type type = std::is_same_v<StructType, FAST_TEST> ? parsing::Type::FAST : parsing::Type::RPN;

    MathWorld<type> world;

    auto& f = world.new_object() = "f( x)  = cos(x) * g(X)";

    expect(f.get_name() == "f");

  } | std::tuple<FAST_TEST, RPN_TEST>{};

}