Serialization: Step 1 Json Parser

As nobody has provided input, I have updated the question. (The next one is coming soon)

Coding to this interface:

namespace ThorsAnvil
{
    namespace Serialization
    {

class ParserInterface
{
    public:
        enum class ParserToken {Error, DocStart, DocEnd, MapStart, MapEnd, ArrayStart, ArrayEnd, Key, Value};
        std::istream&   input;
        ParserToken     pushBack;

        ParserInterface(std::istream& input)
            : input(input)
            , pushBack(ParserToken::Error)
        {}
        virtual ~ParserInterface() {}
                ParserToken     getToken();
                void            pushBackToken(ParserToken token);
        virtual ParserToken     getNextToken()          = 0;
        virtual std::string     getKey()                = 0;

        virtual void    getValue(short int&)             = 0;
        virtual void    getValue(int&)                   = 0;
        virtual void    getValue(long int&)              = 0;
        virtual void    getValue(long long int&)         = 0;

        virtual void    getValue(unsigned short int&)    = 0;
        virtual void    getValue(unsigned int&)          = 0;
        virtual void    getValue(unsigned long int&)     = 0;
        virtual void    getValue(unsigned long long int&)= 0;

        virtual void    getValue(float&)                 = 0;
        virtual void    getValue(double&)                = 0;
        virtual void    getValue(long double&)           = 0;

        virtual void    getValue(bool&)                  = 0;

        virtual void    getValue(std::string&)           = 0;
};

    }
}

The Json Implementation is:

JsonParser.h

```
#ifndef THORS_ANVIL_SERIALIZATION_JSON_PARSER_H
#define THORS_ANVIL_SERIALIZATION_JSON_PARSER_H

#include "Serialize.h"
#include "JsonLexer.h"
#include
#include
#include

namespace ThorsAnvil
{
namespace Serialization
{

class JsonParser: public ParserInterface
{
enum State {Error, Init, OpenM, Key, Colon, ValueM

As an attempt to kill cure (too bad they are still far from being homophones) zombies, let me try write something here. Here's some suggestions:

-
The indentation looks absurd to me:

namespace ThorsAnvil
{
    namespace Serialization
    {

class ParserInterface
{
    // ...
};

    }
}

I would typically do

namespace ThorsAnvil::Serialization {
    class ParserInterface {
        // ...
    };
}

If you really want to get rid of the indentation, you can flush the namespace declarations to the left altogether.

-
There has to be a better way of writing the 17 getValue functions.

-
Are you sure these belong in a general interface? I don't think so.

public:
    std::istream&   input;
    ParserToken     pushBack;

-
Since scan is a template, you should implement it in the header.

-
Is this necessary? At least the comment should be removed. Personally, I would remove the default branch altogether, but that's pretty much a matter of state.

// Anything else just break.
default:
    break;

-
The tables used in the implementation should probably be const.

StackExchange Code Review Q#79279, answer score: 2