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json.h
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json.h
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#pragma once
#include <iostream>
#include <map>
#include <string>
#include <variant>
#include <vector>
namespace json {
class Node;
using Dict = std::map<std::string, Node>;
using Array = std::vector<Node>;
class ParsingError : public std::runtime_error {
public:
using runtime_error::runtime_error;
};
class Node final
: private std::variant<std::nullptr_t, Array, Dict, bool, int, double, std::string> {
public:
using variant::variant;
using Value = variant;
bool IsInt() const {
return std::holds_alternative<int>(*this);
}
int AsInt() const {
using namespace std::literals;
if (!IsInt()) {
throw std::logic_error("Not an int"s);
}
return std::get<int>(*this);
}
bool IsPureDouble() const {
return std::holds_alternative<double>(*this);
}
bool IsDouble() const {
return IsInt() || IsPureDouble();
}
double AsDouble() const {
using namespace std::literals;
if (!IsDouble()) {
throw std::logic_error("Not a double"s);
}
return IsPureDouble() ? std::get<double>(*this) : AsInt();
}
bool IsBool() const {
return std::holds_alternative<bool>(*this);
}
bool AsBool() const {
using namespace std::literals;
if (!IsBool()) {
throw std::logic_error("Not a bool"s);
}
return std::get<bool>(*this);
}
bool IsNull() const {
return std::holds_alternative<std::nullptr_t>(*this);
}
bool IsArray() const {
return std::holds_alternative<Array>(*this);
}
const Array& AsArray() const {
using namespace std::literals;
if (!IsArray()) {
throw std::logic_error("Not an array"s);
}
return std::get<Array>(*this);
}
bool IsString() const {
return std::holds_alternative<std::string>(*this);
}
const std::string& AsString() const {
using namespace std::literals;
if (!IsString()) {
throw std::logic_error("Not a string"s);
}
return std::get<std::string>(*this);
}
bool IsDict() const {
return std::holds_alternative<Dict>(*this);
}
const Dict& AsDict() const {
using namespace std::literals;
if (!IsDict()) {
throw std::logic_error("Not a dict"s);
}
return std::get<Dict>(*this);
}
bool operator==(const Node& rhs) const {
return GetValue() == rhs.GetValue();
}
const Value& GetValue() const {
return *this;
}
};
inline bool operator!=(const Node& lhs, const Node& rhs) {
return !(lhs == rhs);
}
class Document {
public:
explicit Document(Node root)
: root_(std::move(root)) {
}
const Node& GetRoot() const {
return root_;
}
private:
Node root_;
};
inline bool operator==(const Document& lhs, const Document& rhs) {
return lhs.GetRoot() == rhs.GetRoot();
}
inline bool operator!=(const Document& lhs, const Document& rhs) {
return !(lhs == rhs);
}
Document Load(std::istream& input);
void Print(const Document& doc, std::ostream& output);
} // namespace json