op-pedal/src/json.hpp

// Copyright (c) 2021 Robin Davies
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#pragma once
#include <iostream>
#include <cstdint>
#include <boost/utility/string_view.hpp>
#include <boost/format.hpp>
#include <iomanip>
#include <type_traits>
#include <sstream>
#include "HtmlHelper.hpp"
#include <cctype>
#include "PiPedalException.hpp"



#define DECLARE_JSON_MAP(CLASSNAME) \
  static json_map::storage_type<CLASSNAME> jmap

#define JSON_MAP_BEGIN(CLASSNAME) \
 json_map::storage_type<CLASSNAME> CLASSNAME::jmap { {

#define JSON_MAP_REFERENCE(class,name) \
 json_map::reference(#name,&class::name##_),

#define JSON_MAP_REFERENCE_CONDITIONAL(class,name, conditionFn) \
    json_map::conditional_reference(#name,&class::name##_,conditionFn) ,
    

#define JSON_MAP_END() \
}};

namespace pipedal
{

// a function pointer of type bool (*)(const CLASS*,const MEMBER_TYPE&value) (because pre-C++ 20 templated function pointers are *hard*)
template<typename CLASS,typename MEMBER_TYPE> class JsonConditionFunction {
public:
    using Pointer = bool (*)(const CLASS*self,const MEMBER_TYPE&value);
};


//----------------------------------------------------------------------------------


class json_reader;
class json_writer;

class JsonWritable {
public:
    virtual void write_members(json_writer&writer) const = 0;
};

template<typename CLASS>
class json_member_reference_base {
private:
    const char*name_;
protected:
    json_member_reference_base(const char*name)
    :name_(name)
    {
    }
public:
    virtual ~json_member_reference_base() {}
    const char*name() { return this->name_; }
    virtual bool canWrite(const CLASS *self) { return true; }
    virtual void read_value(json_reader&reader, CLASS*self) = 0;
    virtual void write_value(json_writer&writer, const CLASS*self) = 0;
};
template<typename CLASS, typename MEMBER_TYPE>
class json_member_reference: public json_member_reference_base<CLASS> {
public:
    virtual ~json_member_reference() {}
    json_member_reference(const char*name, MEMBER_TYPE CLASS::*member_pointer)
    : json_member_reference_base<CLASS>(name)
    , member_pointer(member_pointer)
    {
    }
    MEMBER_TYPE CLASS::*member_pointer;

    void read_value(json_reader&reader, CLASS*self);
    void write_value(json_writer&writer, const CLASS*self);


};
template<typename CLASS, typename MEMBER_TYPE>
class json_conditional_member_reference: public json_member_reference_base<CLASS> {
public:
    virtual ~json_conditional_member_reference() {}

    json_conditional_member_reference(const char*name, MEMBER_TYPE CLASS::*member_pointer,typename JsonConditionFunction<CLASS,MEMBER_TYPE>::Pointer condition)
    : json_member_reference_base<CLASS>(name)
    , member_pointer(member_pointer)
    , condition_(condition)
    {
    }
    MEMBER_TYPE CLASS::*member_pointer;

    typename JsonConditionFunction<CLASS,MEMBER_TYPE>::Pointer condition_;

    virtual bool canWrite(const CLASS *self);

    void read_value(json_reader&reader, CLASS*self);
    void write_value(json_writer&writer, const CLASS*self);
};



template <typename CLASS>
class json_enum_converter {
public:
    virtual CLASS fromString(const std::string&value) const = 0;
    virtual const std::string& toString(CLASS value) const = 0;
};

template<typename CLASS, typename MEMBER_TYPE>
class json_enum_member_reference: public json_member_reference_base<CLASS> {
public:
    json_enum_member_reference(const char*name, MEMBER_TYPE CLASS::*member_pointer, const json_enum_converter<MEMBER_TYPE>*converter)
    : json_member_reference_base<CLASS>(name)
    , member_pointer(member_pointer)
    , converter_(converter)
    {
    }
    MEMBER_TYPE CLASS::*member_pointer;
    const json_enum_converter<MEMBER_TYPE> *converter_;


    void read_value(json_reader&reader, CLASS*self);
    void write_value(json_writer&writer, const CLASS*self);


};


//----------------------------------------------------------------------------------
class json_map_base {

};

template<typename CLASS>
class json_map_impl: public json_map_base {
private:
    std::vector<json_member_reference_base<CLASS>* > members_;
    json_map_impl(const json_map_impl&) { } // disable copy constructor.
public:
    json_map_impl(std::vector<json_member_reference_base<CLASS>*> members)
    : members_(members)
    {

    }
    virtual ~json_map_impl()
    {
        for (auto member: members_)
        {
            delete member;
        }
        members_.resize(0);
    }
    void read_property(json_reader* reader,const char*memberName,CLASS *pObject);
    void write_members(json_writer* writer, const CLASS*pObject);


};



class json_map {
public:
    template <typename CLASS> class storage_type : public json_map_impl<CLASS> {
    public:
        storage_type(std::vector<json_member_reference_base<CLASS>*> members)
            : json_map_impl<CLASS>(members)
        {
        }
    };
    template <typename CLASS, typename MEMBER_TYPE> 
    static json_member_reference<CLASS,MEMBER_TYPE> *
    reference(const char*name,MEMBER_TYPE CLASS::*member_pointer)
    {
        return new json_member_reference<CLASS,MEMBER_TYPE>(name,member_pointer);
    };
    template <typename CLASS, typename MEMBER_TYPE,typename ENUM_CONVERTER>
    static json_enum_member_reference<CLASS,MEMBER_TYPE> *
    enum_reference(
        const char*name,
        MEMBER_TYPE CLASS::*member_pointer,
        const ENUM_CONVERTER*converter)
    {
        return new json_enum_member_reference<CLASS,MEMBER_TYPE>(name,member_pointer,converter);
    };

    template <typename CLASS, typename MEMBER_TYPE> 
    static json_conditional_member_reference<CLASS,MEMBER_TYPE> *
    conditional_reference(const char*name,MEMBER_TYPE CLASS::*member_pointer,typename JsonConditionFunction<CLASS,MEMBER_TYPE>::Pointer condition  )
    {
        return new json_conditional_member_reference<CLASS,MEMBER_TYPE>(name,member_pointer,condition);
    };

};

//----------------------------------------------------------------------------------

template <typename T>
class HasJsonPropertyMap {

    template <class TYPE>
    static std::true_type test (decltype(TYPE::jmap) *) { return std::true_type();};

    template <class TYPE>
    static std::false_type test (...);

public:
    static constexpr bool value = decltype(test<T>(nullptr))::value;
};


//----------------------------------------------------------------------------------



class json_writer;


class json_writer {
public:
    const char*CRLF;
private:
    std::ostream &os;
    int indent_level;
    bool compressed;
    const int TAB_SIZE = 2;

    const uint16_t UTF16_SURROGATE_1_BASE = 0xD800U;
    const uint16_t UTF16_SURROGATE_2_BASE = 0xDC00U;
    const uint16_t UTF16_SURROGATE_MASK = 0x3FFFU;

    static const uint32_t UTF8_ONE_BYTE_MASK = 0x80;
    static const uint32_t UTF8_ONE_BYTE_BITS = 0;
    static const uint32_t UTF8_TWO_BYTES_MASK = 0xE0;
    static const uint32_t UTF8_TWO_BYTES_BITS = 0xC0;
    static const uint32_t UTF8_THREE_BYTES_MASK = 0xF0;
    static const uint32_t UTF8_THREE_BYTES_BITS = 0xE0;
    static const uint32_t UTF8_FOUR_BYTES_MASK = 0xF8;
    static const uint32_t UTF8_FOUR_BYTES_BITS = 0xF0;
    static const uint32_t UTF8_CONTINUATION_MASK = 0xC0;
    static const uint32_t UTF8_CONTINUATION_BITS = 0x80;


public:
    static std::string encode_string(const std::string &text)
    {
        std::stringstream s;
        json_writer writer(s);
        writer.write(text);
        return s.str();
    }
    void write_raw(const char*text) {
        os << text;
    }
    using string_view = boost::string_view;
    json_writer(std::ostream &os, bool compressed = false)
    : os(os)
    , compressed(compressed)
    , indent_level(0)
    {
        this->CRLF = compressed? "" : "\r\n";
    }
    void write(long long value)
    {
        os << value;
    }
    void write(unsigned long long value)
    {
        os << value;
    }
    void write(long value)
    {
        os << value;
    }
    void write(unsigned long value)
    {
        os << value;
    }
    void write(int value)
    {
        os << value;
    }
    void write(unsigned int value)
    {
        os << value;
    }



private:
    static void throw_encoding_error();

    static  uint32_t continuation_byte(std::string_view::iterator &p, std::string_view::const_iterator end);
    void write_utf16_char(uint16_t uc);

public:
    void indent();
    std::ostream & output_stream() { return os; }

    void write(bool value) {
        os << (value? "true": "false");
    }
    void write(
        string_view v, 
        bool enforceValidUtf8 // throw errors for illegal (non-minimal) UTF-8 sequences.
        );
    void write(string_view v)
    {
        write(v,true);
    }
    void write(const char*p)
    {
        write(string_view(p));
    }

    void write(const std::string&s)
    {
        write(string_view(s.c_str()));
    }
    void write(float f)
    {
        os <<  std::setprecision(std::numeric_limits<float>::max_digits10) << f;  // round-trip format
    }
    void write(double f)
    {
        os <<  std::setprecision(std::numeric_limits<double>::max_digits10) << f;  // round-trip format
    }

    template <typename T> void write(const std::vector<T> &value)
    {
        if (std::is_fundamental<T>() || std::is_assignable<T,const char*>() || value.size() == 0)
        {
            // simple types: all on same line.
            os << "[ ";
            
            if (value.size() >= 1)
            {
                write(value[0]);
            }
            for (size_t i = 1; i < value.size(); ++i)
            {
                os << ",";
                write(value[i]);
            }
            os << "]";
        } else {
            // complex types: one line per entry.
            os << "[" << CRLF;
            indent_level += TAB_SIZE;
            bool first = true;
            for (size_t i = 0; i < value.size(); ++i)
            {
                if (!first)
                {
                    os << ',' << CRLF;
                }
                first = false;
                indent();
                write(value[i]);
            }
            indent_level -= TAB_SIZE;
            os << CRLF;
            indent();
            os << "]";

        }
    }
    template<
    class Category,
    class T,
    class Distance = std::ptrdiff_t,
    class Pointer = T*,
    class Reference = T&
    >  void write(std::iterator<Category,T,Distance,Pointer,Reference> &it) {
        start_array();
        bool first = true;
        for( Reference ref: it)
        {
            if (!first)
            {
                os << ", ";
                os << CRLF;
            }
            indent();
            os << ref;
        }
        end_array();
    }

    void write_json_member(const char*name, const char*json_text)
    {
        write(name);
        os << ": ";
        os << json_text;
    }

    template<typename T> void write_member(const char*name,const T&value)
    {
        write(name);
        os << ": ";
        write(value);
    }
    void start_object();
    void end_object();
    void start_array();
    void end_array();


/*
    void write(const json_writable *obj)
    {
        if (obj == nullptr)
        {
            os << "null";
        } else {
            start_object();
            obj->write(*this);
            end_object();
        }
    }
    void write(const json_writable &obj)
    {
        start_object();
        obj.write(*this);
        end_object();
    }
*/
private:
    template<typename T>
    json_map::storage_type<T>& get_object_map()
    {
        //static_assert(HasJsonPropertyMap<T>::value,"Type does not have a Json propery map name jmap.");
        // Type T must have public static propery jmap.
        return T::jmap;
    }
public:

    void write(const JsonWritable*pWritable)
    {
        start_object();
        pWritable->write_members(*this);
        end_object();
    }
    template <typename T> 
    void write(const std::shared_ptr<T> &obj)
    {
        write(obj.get());
    }
    template <typename T> 
    void write(const std::weak_ptr<T> &obj)
    {
        auto p = obj.lock();
        write(p.get());
    }
    template <typename T> 
    void write(const std::unique_ptr<T> &obj)
    {
        write(obj.get());
    }

    template <typename T> 
    void write(const T*obj)
    {
        static_assert(HasJsonPropertyMap<T>::value,"Json serialization type not supported. (Json object classes must have a Json property map named jmap).");
        if (obj == nullptr)
        {
            write_raw("null");
        } else {
            write(*obj);
        }

    }
    template <typename T> 
    void write(T*obj)
    {
        static_assert(HasJsonPropertyMap<T>::value,"Json serialization type not supported. (Json object classes must have a Json property map named jmap).");
        if (obj == nullptr)
        {
            write_raw("null");
        } else {
            write(*obj);
        }

    }

    template <typename T> 
    void write(const T&obj)
    {
        static_assert(HasJsonPropertyMap<T>::value,"Json serialization type not supported. (Json object classes must have a Json property map named jmap).");

        auto &map = get_object_map<T>();
        start_object();

        map.write_members(this,&obj);

        end_object();
    }




};


class json_reader {
    std::istream &is_;

    const uint16_t UTF16_SURROGATE_1_BASE = 0xD800U;
    const uint16_t UTF16_SURROGATE_2_BASE = 0xDC00U;
    const uint16_t UTF16_SURROGATE_MASK = 0x3FFU;


public:
    json_reader(std::istream &input)
    : is_(input)
    {

    }

private:
    void throw_format_error(const char*error);

    void throw_format_error() 
    {
        throw_format_error("Invalid file format");
    }



    inline bool is_whitespace(char c)
    {
        switch (c)
        {
        case 0x20:
        case 0x0A:
        case 0x0D:
        case 0x09:
            return true;
        default: 
            return false;
        }

    }
    char get() {
        int ic = is_.get();
        if (ic == -1) throw_format_error("Unexpected end of file");
        return (char)ic;
    }
    
    void skip_whitespace();

    void read_object_start();
    uint16_t read_hex();
    uint16_t read_u_escape();

    template<typename T>
    json_map::storage_type<T>& get_object_map()
    {
        // Type T must have public static propery map.
        return T::jmap;
    }
public:    
    void consume(char expected);
    void consumeToken(const char*expectedToken, const char*errorMessage);
    int peek()
    {
        skip_whitespace();
        return is_.peek();
    }
public:
    std::string read_string();

public:
    bool is_complete();

    template<typename T>
    void read(T*pObject)
    {
        char c;
        consume('{');
        
        auto &map = get_object_map<T>();
        while (true)
        {
            c = peek();
            if (c == '}')
            {
                c = get();
                break;
            }
            std::string memberName = read_string();

            consume(':');
            skip_whitespace();
            
            map.read_property(this,memberName.c_str(),pObject);
            
            skip_whitespace();
            if (is_.peek() == ',')
            {
                c = get();
            }
        }
    }
    template<typename T>
    void read(T**pObject)
    {
        int c = peek();
        if (c != '{')
        {
            if (c == 'n')
            {
                consumeToken("null", "Expecting '{' or 'null'.");
                *pObject = nullptr;
                return;
            }
        }
        *pObject = new T();
        read(*pObject);
    }

    template<typename T>
    void read(std::unique_ptr<T> *pUniquePtr)
    {
        std::unique_ptr<T> p = std::make_unique<T>();

        read(p.get());
        *pUniquePtr = std::move(p);
    }
    template<typename T>
    void read(std::shared_ptr<T> *pUniquePtr)
    {
        std::shared_ptr<T> p = std::make_shared<T>();

        read(p.get());
        (*pUniquePtr) = std::move(p);
    }
    template<typename T>
    void read(std::weak_ptr<T> *pUniquePtr)
    {
        throw std::domain_error("Can't read std::weak_ptr");
    }

private:
    void skip_string();
    void skip_number();
    void skip_array();
    void skip_object();
    std::string readToken();
    bool read_boolean();
    void read_null();
    void skip_token();
public:
    void skip_property();

    void read(std::string*value) {
        skip_whitespace();
        *value = read_string();
    }

    void read(bool *value)
    {
        skip_whitespace();
        *value = read_boolean();
    }
    void read(int *value) {
        skip_whitespace();
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(long*value)
    {
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(long long*value) {
        skip_whitespace();
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(unsigned int*value)
    {
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(unsigned long*value)
    {
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(unsigned long long*value) {
        skip_whitespace();
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }

    void read(float*value) {
        skip_whitespace();
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    void read(double*value) {
        skip_whitespace();
        is_ >> *value;
        if (is_.fail()) throw PiPedalException("Invalid format.");
    }
    template <typename T>
    void read(std::vector<T>*value)
    {
        char c;
        std::vector<T> result;

        consume('[');
        while (true)
        {
            if (peek() == ']')
            {
                c = get();
                break;
            }
            T item;
            read(&item);
            result.push_back(std::move(item));
            if (peek() == ',')
            {
                c = get();
            }
        }
        *value = std::move(result);
    }
    

};

template <typename T>
class HasJsonRead {


    template <typename TYPE, typename ARG>
    static std::true_type test (decltype(json_reader(std::cin).read((ARG*)nullptr))*v) { return std::true_type();};

    template <typename TYPE, typename ARG>
    static std::false_type test (...);

public:
    static constexpr bool value = decltype(test<json_reader,T>(nullptr))::value;
};



template<typename CLASS, typename MEMBER_TYPE>
void json_member_reference<CLASS, MEMBER_TYPE>::read_value(json_reader&reader, CLASS*self) {
    static_assert(HasJsonRead<MEMBER_TYPE>::value,"Type not supported for Json serialization.");
    MEMBER_TYPE *ref = &((*self).*member_pointer);
    reader.read(ref);
}
template<typename CLASS, typename MEMBER_TYPE>
void json_member_reference<CLASS,MEMBER_TYPE>::write_value(json_writer&writer, const CLASS*self) {
    const MEMBER_TYPE &ref = (*self).*member_pointer;
    writer.write_member(this->name(),ref);
}   

template<typename CLASS, typename MEMBER_TYPE>
void json_enum_member_reference<CLASS, MEMBER_TYPE>::read_value(json_reader&reader, CLASS*self) {
    MEMBER_TYPE *ref = &((*self).*member_pointer);
    std::string val = reader.read_string();
    *ref = converter_->fromString(val);
}

template<typename CLASS, typename MEMBER_TYPE>
void json_enum_member_reference<CLASS,MEMBER_TYPE>::write_value(json_writer&writer, const CLASS*self) {
    const MEMBER_TYPE &ref = (*self).*member_pointer;
    std::string val = converter_->toString(ref);
    writer.write_member(this->name(),val);
}   


template <typename CLASS>
void json_map_impl<CLASS>::read_property(json_reader* reader,const char*memberName,CLASS *pObject)
{
    for (json_member_reference_base<CLASS>*member: members_)
    {
        if (strcmp(member->name(),memberName) == 0)
        {
            member->read_value(*reader,pObject);
            return;
        }

    }
    reader->skip_property();
}

template<typename CLASS, typename MEMBER_TYPE>
void json_conditional_member_reference<CLASS, MEMBER_TYPE>::read_value(json_reader&reader, CLASS*self) {
    static_assert(HasJsonRead<MEMBER_TYPE>::value,"Type not supported for Json serialization.");
    MEMBER_TYPE *ref = &((*self).*member_pointer);
    reader.read(ref);
}

template<typename CLASS, typename MEMBER_TYPE>
bool json_conditional_member_reference<CLASS,MEMBER_TYPE>::canWrite(const CLASS*self) {
    const MEMBER_TYPE &ref = (*self).*member_pointer;
    return this->condition_(self,ref);

}


template<typename CLASS, typename MEMBER_TYPE>
void json_conditional_member_reference<CLASS,MEMBER_TYPE>::write_value(json_writer&writer, const CLASS*self) {
    const MEMBER_TYPE &ref = (*self).*member_pointer;
    writer.write_member(this->name(),ref);
}   


template <typename CLASS>
void json_map_impl<CLASS>::write_members(json_writer* writer, const CLASS*pObject)
{
    bool first = true;
    for (json_member_reference_base<CLASS>*member: members_)
    {
        if (member->canWrite(pObject))
        {
            if (!first)
            {
                writer->output_stream() << ',';
                writer->output_stream() << writer->CRLF;
            }
            first = false;
            writer->indent();
            member->write_value(*writer,pObject);
        }
    }
    
}






} // namespace pipedal