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Util: Implement copy-and-swap idiom and the Rule of Five in Value

master
Riyyi 2 years ago
parent
a1bb1b93c9
commit
3e69abdfa0
5 changed files with 131 additions and 92 deletions
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  1. 1
      src/util/json/array.h
  2. 1
      src/util/json/object.h
  3. 38
      src/util/json/tojson.h
  4. 161
      src/util/json/value.cpp
  5. 22
      src/util/json/value.h

1
src/util/json/array.h
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@ -30,6 +30,7 @@ public:
{
}
void clear() { m_elements.clear(); }
void emplace_back(Value element);
void reserve(size_t size) { m_elements.reserve(size); }

1
src/util/json/object.h
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@ -27,6 +27,7 @@ public:
{
}
void clear() { m_members.clear(); }
void emplace(const std::string& name, Value value);
Value& operator[](const std::string& name);

38
src/util/json/tojson.h
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@ -26,7 +26,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, bool boolean)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Bool;
json.m_value.boolean = boolean;
}
@ -34,7 +34,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, int number)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Number;
json.m_value.number = (double)number;
}
@ -42,7 +42,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, double number)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Number;
json.m_value.number = number;
}
@ -50,7 +50,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, const char* string)
{
json.clear();
json.destroy();
json.m_type = Json::Type::String;
json.m_value.string = new std::string(string);
}
@ -58,7 +58,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, const std::string& string)
{
json.clear();
json.destroy();
json.m_type = Json::Type::String;
json.m_value.string = new std::string(string);
}
@ -66,7 +66,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, const Array& array)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Array;
json.m_value.array = new Array(array);
}
@ -74,7 +74,7 @@ struct jsonConstructor {
template<typename Json, typename T>
static void construct(Json& json, const std::vector<T>& array)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Array;
json.m_value.array = new Array;
json.m_value.array->reserve(array.size());
@ -86,7 +86,7 @@ struct jsonConstructor {
template<typename Json>
static void construct(Json& json, const Object& object)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Object;
json.m_value.object = new Object(object);
}
@ -94,7 +94,7 @@ struct jsonConstructor {
template<typename Json, typename T>
static void construct(Json& json, const std::map<std::string, T>& object)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Object;
json.m_value.object = new Object;
for (const auto& [name, value] : object) {
@ -105,7 +105,7 @@ struct jsonConstructor {
template<typename Json, typename T>
static void construct(Json& json, const std::unordered_map<std::string, T>& object)
{
json.clear();
json.destroy();
json.m_type = Json::Type::Object;
json.m_value.object = new Object;
for (const auto& [name, value] : object) {
@ -143,14 +143,14 @@ constexpr const auto& toJson = Detail::staticConst<Detail::toJsonFunction>; // N
// Customization Points
// https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4381.html
// Json::fromJson is a function object, the type of which is
// Json::Detail::fromJsonFunction. In the Json::Detail namespace are the
// fromJson free functions. The function call operator of fromJsonFunction makes
// an unqualified call to fromJson which, since it shares the Detail namespace
// with the fromJson free functions, will consider those in addition to any
// overloads that are found by argument-dependent lookup.
// Json::toJson is a function object, the type of which is
// Json::Detail::toJsonFunction. In the Json::Detail namespace are the toJson
// free functions. The function call operator of toJsonFunction makes an
// unqualified call to toJson which, since it shares the Detail namespace with
// the toJson free functions, will consider those in addition to any overloads
// that are found by argument-dependent lookup.
// Variable templates are linked externally, therefor every translation unit
// will see the same address for Detail::staticConst<Detail::fromJsonFunction>.
// Since Json::fromJson is a reference to the variable template, it too will
// have the same address in all translation units.
// will see the same address for Detail::staticConst<Detail::toJsonFunction>.
// Since Json::toJson is a reference to the variable template, it too will have
// the same address in all translation units.

161
src/util/json/value.cpp
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@ -9,7 +9,7 @@
#include <cstdint> // uint32_t
#include <iostream> // istream, ostream
#include <string>
#include <utility> // move
#include <utility> // move, swap
#include "util/json/array.h"
#include "util/json/job.h"
@ -27,7 +27,26 @@ Value::Value(std::nullptr_t)
Value::Value(Type type)
: m_type(type)
{
create();
switch (m_type) {
case Type::Bool:
m_value.boolean = false;
break;
case Type::Number:
m_value.number = 0.0;
break;
case Type::String:
m_value.string = new std::string;
break;
case Type::Array:
m_value.array = new Array;
break;
case Type::Object:
m_value.object = new Object;
break;
case Type::Null:
default:
break;
}
}
Value::Value(const std::initializer_list<Value>& values)
@ -48,36 +67,94 @@ Value::Value(const std::initializer_list<Value>& values)
for (auto& value : values) {
m_value.object->emplace(std::move(*value[0].m_value.string),
std::move(value[1]));
std::move(value[1]));
}
}
}
// Copy constructor
Value::Value(const Value& other)
: m_type(other.m_type)
{
copyFrom(other);
switch (m_type) {
case Type::Bool:
m_value.boolean = other.m_value.boolean;
break;
case Type::Number:
m_value.number = other.m_value.number;
break;
case Type::String:
m_value.string = new std::string(*other.m_value.string);
break;
case Type::Array:
m_value.array = new Array(*other.m_value.array);
break;
case Type::Object:
m_value.object = new Object(*other.m_value.object);
break;
case Type::Null:
default:
break;
}
}
// Assignment operator
Value& Value::operator=(const Value& other)
// Move constructor
Value::Value(Value&& other) noexcept
: Value(Type::Null) // Initialize via default construction
{
if (this != &other) {
clear();
copyFrom(other);
}
// Allow std::swap as a fallback on ADL failure
using std::swap;
// Unqualified call to swap, allow ADL to operate and find best match
swap(*this, other);
}
// Copy assignment
// Move assignment
Value& Value::operator=(Value other)
{
// Allow std::swap as a fallback on ADL failure
using std::swap;
// Unqualified call to swap, allow ADL to operate and find best match
swap(*this, other);
return *this;
}
void swap(Value& left, Value& right) noexcept
{
std::swap(left.m_type, right.m_type);
std::swap(left.m_value, right.m_value);
}
// ------------------------------------------
Value Value::parse(const std::string& input)
void Value::clear()
{
Job job(input);
Value value = job.fire();
switch (m_type) {
case Type::Bool:
m_value.boolean = false;
break;
case Type::Number:
m_value.number = 0.0;
break;
case Type::String:
m_value.string->clear();
break;
case Type::Array:
m_value.array->clear();
break;
case Type::Object:
m_value.object->clear();
break;
case Type::Null:
default:
break;
}
}
return value;
Value Value::parse(const std::string& input)
{
return Job(input).fire();
}
std::string Value::dump(const uint32_t indent, const char indentCharacter) const
@ -190,45 +267,21 @@ size_t Value::size() const
switch (m_type) {
case Type::Null:
return 0;
case Type::Bool:
case Type::Number:
case Type::String:
return 1;
case Type::Array:
return m_value.array->size();
case Type::Object:
return m_value.object->size();
default:
return 1;
}
}
// ------------------------------------------
void Value::create()
{
switch (m_type) {
case Type::Bool:
m_value.boolean = false;
break;
case Type::Number:
m_value.number = 0.0;
break;
case Type::String:
m_value.string = new std::string;
break;
case Type::Array:
m_value.array = new Array;
break;
case Type::Object:
m_value.object = new Object;
break;
default:
break;
return 1;
}
}
void Value::clear()
// ------------------------------------------
void Value::destroy()
{
switch (m_type) {
case Type::String:
@ -240,31 +293,9 @@ void Value::clear()
case Type::Object:
delete m_value.object;
break;
default:
break;
}
}
void Value::copyFrom(const Value& other)
{
m_type = other.m_type;
switch (m_type) {
case Type::Null:
case Type::Bool:
m_value.boolean = other.m_value.boolean;
break;
case Type::Number:
m_value.number = other.m_value.number;
break;
case Type::String:
m_value.string = new std::string(*other.m_value.string);
break;
case Type::Array:
m_value.array = new Array(*other.m_value.array);
break;
case Type::Object:
m_value.object = new Object(*other.m_value.object);
break;
default:
break;
}

22
src/util/json/value.h
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@ -38,6 +38,8 @@ public:
Object, // {}
};
// --------------------------------------
// Constructors
Value(std::nullptr_t = nullptr);
Value(Type type);
@ -48,20 +50,26 @@ public:
toJson(*this, std::forward<T>(value));
}
// Destructor
virtual ~Value() { clear(); }
// Rule of Five:
// Copy constructor
Value(const Value& other);
// Move constructor
Value(Value&& other) noexcept;
// Copy assignment
// Move assignment
Value& operator=(Value other);
// Destructor
virtual ~Value() { destroy(); }
// Assignment operator
Value& operator=(const Value& other);
friend void swap(Value& left, Value& right) noexcept;
// --------------------------------------
static Value parse(const std::string& input);
std::string dump(const uint32_t indent = 0, const char indentCharacter = ' ') const;
void clear();
void emplace_back(Value value);
void emplace(const std::string& key, Value value);
@ -109,9 +117,7 @@ public:
const Object& asObject() const { return *m_value.object; }
private:
void create();
void clear();
void copyFrom(const Value& other);
void destroy();
Type m_type { Type::Null };

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