Lab 6

Implement the following classes that represents json objects:

• base class JsonValue with an abstract destructor and an abstract print function that takes an ostream&
• NullValue: represents a null
• NumberValue: stores a number
• BoolValue: stores a bool
• StringValue: stores a string (max size 255)
• ArrayValue: stores an array of values (max 16); the add function will take a value pointer and add it to the array
• ObjectValue: stores an array of pairs of (name, value) (max 16); the add function will take a string for name and a pointer for the value and add it.

Also add a cast operator to unsigned that returns the number of nodes.

You may have all the class declarations in a single header, and all the definitions in a cpp.

The print function will print the tree in such a way that the output is valid json.

Bonus 1: make the print function constant. Bonus 2: make sure there are no memory leaks. Bonus 3: add a command line argument that says whether the output should go to stdout or to a file, and which file. Bonus 4: make the print function print with proper indentation with the help of a new argument.

The base class will look like this:

class JsonValue {
public:
    virtual ~JsonValue() = 0;

    virtual void print(std::ostream& out) = 0;
};

Take the following code:

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

int main() {
    auto array_numbers = new ArrayValue();
    array_numbers->add(new NumberValue(5));
    array_numbers->add(new NumberValue(10));
    array_numbers->add(new NumberValue(15));

    auto array_strings = new ArrayValue();
    array_strings->add(new StringValue("abc"));
    array_strings->add(new StringValue("def"));
    array_strings->add(new StringValue("ghi"));

    auto subobject = new ObjectValue();
    subobject->add("email", new StringValue("t@gmail.com"));
    subobject->add("name", new StringValue("T"));
    subobject->add("online", new BoolValue(true));

    auto object = new ObjectValue();
    object->add("n", new NullValue());
    object->add("array_numbers", array_numbers);
    object->add("array_strings", array_strings);
    object->add("info", subobject);

    std::cout << "Top node has " << (unsigned) *object << " subnodes\n";

    object->print(std::cout);
}

The last object->print(std::cout) should print something like:

{"n": null, "array_numbers": [5, 10, 15], "array_strings": ["abc", "def", "ghi"], "info": {"email": "t@gmail.com", "name": "T", "online": true}}

Check your output corectness here.