cpp-json/test/json_binder_custom.t.h

//
//  json_binder_custom.t.h
//  json
//
//  Created by Sam Jaffe on 9/12/17.
//

#pragma once

#include <cxxtest/TestSuite.h>
#include "json/json_binder.hpp"

#include <iomanip>

using namespace json::binder;
using namespace json::parser;

class precision_binder : public binder_impl<double> {
public:
  precision_binder(int d) : digits(d), trunc(std::pow(10, d)) {}
  virtual ~precision_binder() = default;
  
  binder_impl<double> * clone() const override {
    return new precision_binder{*this};
  }
  
  void parse(double & value, char const * & str, options) const override {
    std::sscanf(str, "%lf", &value);
    value = static_cast<long long>(value * trunc) / trunc;
    json::parse_discard_token(str); // Advance to the boundary
  }
  
  void write(double const & value, std::ostream & out) const override {
    out << std::fixed << std::setprecision(digits) << value;
  }
private:
  int digits;
  double trunc;
};

class json_binder_custom_TestSuite : public CxxTest::TestSuite {
public:
  struct TestObject {
    double A; // four_digits
    double B; // two_digits
    double C;
    bool operator==(TestObject const & other) const {
      return A == other.A && B == other.B && C == other.C;
    }
  };
  
  static object_binder<TestObject> GetImpl() {
    return object_binder<TestObject>()
    ("A", &TestObject::A, precision_binder(4))
    ("B", &TestObject::B, precision_binder(2))
    ("C", &TestObject::C);
  }
  
  static object_binder<TestObject> & Get() {
    static object_binder<TestObject> val = GetImpl();
    return val;
  }
  
  void test_() {
    char data[] = "{\"A\":1.00008, \"B\":1.0, \"C\":1.523211102}";
    TestObject out{0.0, 0.0, 0.0};
    TestObject const expected{1.0, 1.0, 1.523211102};
    TS_ASSERT_THROWS_NOTHING(parse(json::binder::bind(out, Get()), data));
    TS_ASSERT_EQUALS(out, expected);
  }
};