Crow/include/crow/json.h

#pragma once

//#define CROW_JSON_NO_ERROR_CHECK
//#define CROW_JSON_USE_MAP

#include <string>
#ifdef CROW_JSON_USE_MAP
#include <map>
#else
#include <unordered_map>
#endif
#include <iostream>
#include <algorithm>
#include <memory>
#include <boost/lexical_cast.hpp>
#include <boost/algorithm/string/predicate.hpp>
#include <boost/operators.hpp>
#include <vector>

#include "crow/settings.h"
#include "crow/returnable.h"

#if defined(__GNUG__) || defined(__clang__)
#define crow_json_likely(x) __builtin_expect(x, 1)
#define crow_json_unlikely(x) __builtin_expect(x, 0)
#else
#define crow_json_likely(x) x
#define crow_json_unlikely(x) x
#endif


namespace crow
{
    namespace mustache
    {
        class template_t;
    }

    namespace json
    {
        inline void escape(const std::string& str, std::string& ret)
        {
            ret.reserve(ret.size() + str.size()+str.size()/4);
            for(unsigned char c:str)
            {
                switch(c)
                {
                    case '"': ret += "\\\""; break;
                    case '\\': ret += "\\\\"; break;
                    case '\n': ret += "\\n"; break;
                    case '\b': ret += "\\b"; break;
                    case '\f': ret += "\\f"; break;
                    case '\r': ret += "\\r"; break;
                    case '\t': ret += "\\t"; break;
                    default:
                        if (c < 0x20)
                        {
                            ret += "\\u00";
                            auto to_hex = [](char c)
                            {
                                c = c&0xf;
                                if (c < 10)
                                    return '0' + c;
                                return 'a'+c-10;
                            };
                            ret += to_hex(c/16);
                            ret += to_hex(c%16);
                        }
                        else
                            ret += c;
                        break;
                }
            }
        }
        inline std::string escape(const std::string& str)
        {
            std::string ret;
            escape(str, ret);
            return ret;
        }

        enum class type : char
        {
            Null,
            False,
            True,
            Number,
            String,
            List,
            Object,
        };

        inline const char* get_type_str(type t) {
            switch(t){
                case type::Number: return "Number";
                case type::False: return "False";
                case type::True: return "True";
                case type::List: return "List";
                case type::String: return "String";
                case type::Object: return "Object";
                default: return "Unknown";
            }
        }

        enum class num_type : char {
            Signed_integer,
            Unsigned_integer,
            Floating_point,
            Null
        };

        class rvalue;
        rvalue load(const char* data, size_t size);

        namespace detail 
        {
            /// A read string implementation with comparison functionality.
            struct r_string 
                : boost::less_than_comparable<r_string>,
                boost::less_than_comparable<r_string, std::string>,
                boost::equality_comparable<r_string>,
                boost::equality_comparable<r_string, std::string>
            {
                r_string() {};
                r_string(char* s, char* e)
                    : s_(s), e_(e)
                {};
                ~r_string()
                {
                    if (owned_)
                        delete[] s_;
                }

                r_string(const r_string& r)
                {
                    *this = r;
                }

                r_string(r_string&& r)
                {
                    *this = r;
                }

                r_string& operator = (r_string&& r)
                {
                    s_ = r.s_;
                    e_ = r.e_;
                    owned_ = r.owned_;
                    if (r.owned_)
                        r.owned_ = 0;
                    return *this;
                }

                r_string& operator = (const r_string& r)
                {
                    s_ = r.s_;
                    e_ = r.e_;
                    owned_ = 0;
                    return *this;
                }

                operator std::string () const
                {
                    return std::string(s_, e_);
                }


                const char* begin() const { return s_; }
                const char* end() const { return e_; }
                size_t size() const { return end() - begin(); }

                using iterator = const char*;
                using const_iterator = const char*;

                char* s_; ///< Start.
                mutable char* e_; ///< End.
                uint8_t owned_{0};
                friend std::ostream& operator << (std::ostream& os, const r_string& s)
                {
                    os << static_cast<std::string>(s);
                    return os;
                }
            private:
                void force(char* s, uint32_t length)
                {
                    s_ = s;
                    e_ = s_ + length;
                    owned_ = 1;
                }
                friend rvalue crow::json::load(const char* data, size_t size);
            };

            inline bool operator < (const r_string& l, const r_string& r)
            {
                return boost::lexicographical_compare(l,r);
            }

            inline bool operator < (const r_string& l, const std::string& r)
            {
                return boost::lexicographical_compare(l,r);
            }

            inline bool operator > (const r_string& l, const std::string& r)
            {
                return boost::lexicographical_compare(r,l);
            }

            inline bool operator == (const r_string& l, const r_string& r)
            {
                return boost::equals(l,r);
            }

            inline bool operator == (const r_string& l, const std::string& r)
            {
                return boost::equals(l,r);
            }
        }

        /// JSON read value.

        ///
        /// Value can mean any json value, including a JSON object.
        /// Read means this class is used to primarily read strings into a JSON value.
        class rvalue
        {
            static const int cached_bit = 2;
            static const int error_bit = 4;
        public:
            rvalue() noexcept : option_{error_bit} 
            {}
            rvalue(type t) noexcept
                : lsize_{}, lremain_{}, t_{t}
            {}
            rvalue(type t, char* s, char* e)  noexcept
                : start_{s},
                end_{e},
                t_{t}
            {
                determine_num_type();
            }

            rvalue(const rvalue& r)
            : start_(r.start_),
                end_(r.end_),
                key_(r.key_),
                t_(r.t_),
                nt_(r.nt_),
                option_(r.option_)
            {
                copy_l(r);
            }

            rvalue(rvalue&& r) noexcept
            {
                *this = std::move(r);
            }

            rvalue& operator = (const rvalue& r)
            {
                start_ = r.start_;
                end_ = r.end_;
                key_ = r.key_;
                t_ = r.t_;
                nt_ = r.nt_;
                option_ = r.option_;
                copy_l(r);
                return *this;
            }
            rvalue& operator = (rvalue&& r) noexcept
            {
                start_ = r.start_;
                end_ = r.end_;
                key_ = std::move(r.key_);
                l_ = std::move(r.l_);
                lsize_ = r.lsize_;
                lremain_ = r.lremain_;
                t_ = r.t_;
                nt_ = r.nt_;
                option_ = r.option_;
                return *this;
            }

            explicit operator bool() const noexcept
            {
                return (option_ & error_bit) == 0;
            }

            explicit operator int64_t() const
            {
                return i();
            }

            explicit operator uint64_t() const
            {
                return u();
            }

            explicit operator int() const
            {
                return static_cast<int>(i());
            }

            ///Return any json value (not object or list) as a string.
            explicit operator std::string() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() == type::Object || t() == type::List)
                    throw std::runtime_error("json type container");
#endif
                switch (t())
                {
                    case type::String:
                        return std::string(s());
                    case type::Null:
                        return std::string("null");
                    case type::True:
                        return std::string("true");
                    case type::False:
                        return std::string("false");
                    default:
                        return std::string(start_, end_-start_);
                }
            }

            /// The type of the JSON value.
            type t() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (option_ & error_bit)
                {
                    throw std::runtime_error("invalid json object");
                }
#endif
                return t_;
            }

            /// The number type of the JSON value.
            num_type nt() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (option_ & error_bit)
                {
                    throw std::runtime_error("invalid json object");
                }
#endif
                return nt_;
            }

            /// The integer value.
            int64_t i() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                switch (t()) {
                    case type::Number:
                    case type::String:
                        return boost::lexical_cast<int64_t>(start_, end_-start_);
                    default:
                        const std::string msg = "expected number, got: "
                            + std::string(get_type_str(t()));
                        throw std::runtime_error(msg);
                }
#endif
                return boost::lexical_cast<int64_t>(start_, end_-start_);
            }

            /// The unsigned integer value.
            uint64_t u() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                switch (t()) {
                    case type::Number:
                    case type::String:
                        return boost::lexical_cast<uint64_t>(start_, end_-start_);
                    default:
                        throw std::runtime_error(std::string("expected number, got: ") + get_type_str(t()));
                }
#endif
                return boost::lexical_cast<uint64_t>(start_, end_-start_);
            }

            /// The double precision floating-point number value.
            double d() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Number)
                    throw std::runtime_error("value is not number");
#endif
                return boost::lexical_cast<double>(start_, end_-start_);
            }

            /// The boolean value.
            bool b() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::True && t() != type::False)
                    throw std::runtime_error("value is not boolean");
#endif
                return t() == type::True;
            }

            /// The string value.
            detail::r_string s() const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::String)
                    throw std::runtime_error("value is not string");
#endif
                unescape();
                return detail::r_string{start_, end_};
            }

            ///The list or object value
            std::vector<rvalue> lo()
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object && t() != type::List)
                    throw std::runtime_error("value is not a container");
#endif
                std::vector<rvalue> ret;
                ret.reserve(lsize_);
                for (uint32_t i = 0; i<lsize_; i++)
                {
                    ret.emplace_back(l_[i]);
                }
                return ret;
            }

            /// Convert escaped string character to their original form ("\\n" -> '\n').
            void unescape() const
            {
                if (*(start_-1))
                {
                    char* head = start_;
                    char* tail = start_;
                    while(head != end_)
                    {
                        if (*head == '\\')
                        {
                            switch(*++head)
                            {
                                case '"':  *tail++ = '"'; break;
                                case '\\': *tail++ = '\\'; break;
                                case '/':  *tail++ = '/'; break;
                                case 'b':  *tail++ = '\b'; break;
                                case 'f':  *tail++ = '\f'; break;
                                case 'n':  *tail++ = '\n'; break;
                                case 'r':  *tail++ = '\r'; break;
                                case 't':  *tail++ = '\t'; break;
                                case 'u':
                                    {
                                        auto from_hex = [](char c)
                                        {
                                            if (c >= 'a')
                                                return c - 'a' + 10;
                                            if (c >= 'A')
                                                return c - 'A' + 10;
                                            return c - '0';
                                        };
                                        unsigned int code = 
                                            (from_hex(head[1])<<12) + 
                                            (from_hex(head[2])<< 8) + 
                                            (from_hex(head[3])<< 4) + 
                                            from_hex(head[4]);
                                        if (code >= 0x800)
                                        {
                                            *tail++ = 0xE0 | (code >> 12);
                                            *tail++ = 0x80 | ((code >> 6) & 0x3F);
                                            *tail++ = 0x80 | (code & 0x3F);
                                        }
                                        else if (code >= 0x80)
                                        {
                                            *tail++ = 0xC0 | (code >> 6);
                                            *tail++ = 0x80 | (code & 0x3F);
                                        }
                                        else
                                        {
                                            *tail++ = code;
                                        }
                                        head += 4;
                                    }
                                    break;
                            }
                        }
                        else
                            *tail++ = *head;
                        head++;
                    }
                    end_ = tail;
                    *end_ = 0;
                    *(start_-1) = 0;
                }
            }

            ///Check if the json object has the passed string as a key.
            bool has(const char* str) const
            {
                return has(std::string(str));
            }

            bool has(const std::string& str) const
            {
                struct Pred 
                {
                    bool operator()(const rvalue& l, const rvalue& r) const
                    {
                        return l.key_ < r.key_;
                    };
                    bool operator()(const rvalue& l, const std::string& r) const
                    {
                        return l.key_ < r;
                    };
                    bool operator()(const std::string& l, const rvalue& r) const
                    {
                        return l < r.key_;
                    };
                };
                if (!is_cached())
                {
                    std::sort(begin(), end(), Pred());
                    set_cached();
                }
                auto it = lower_bound(begin(), end(), str, Pred());
                return it != end() && it->key_ == str;
            }

            int count(const std::string& str)
            {
                return has(str) ? 1 : 0;
            }

            rvalue* begin() const 
            { 
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object && t() != type::List)
                    throw std::runtime_error("value is not a container");
#endif
                return l_.get(); 
            }
            rvalue* end() const 
            { 
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object && t() != type::List)
                    throw std::runtime_error("value is not a container");
#endif
                return l_.get()+lsize_; 
            }

            const detail::r_string& key() const
            {
                return key_;
            }

            size_t size() const
            {
                if (t() == type::String)
                    return s().size();
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object && t() != type::List)
                    throw std::runtime_error("value is not a container");
#endif
                return lsize_;
            }

            const rvalue& operator[](int index) const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::List)
                    throw std::runtime_error("value is not a list");
                if (index >= static_cast<int>(lsize_) || index < 0)
                    throw std::runtime_error("list out of bound");
#endif
                return l_[index];
            }

            const rvalue& operator[](size_t index) const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::List)
                    throw std::runtime_error("value is not a list");
                if (index >= lsize_)
                    throw std::runtime_error("list out of bound");
#endif
                return l_[index];
            }

            const rvalue& operator[](const char* str) const
            {
                return this->operator[](std::string(str));
            }

            const rvalue& operator[](const std::string& str) const
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object)
                    throw std::runtime_error("value is not an object");
#endif
                struct Pred 
                {
                    bool operator()(const rvalue& l, const rvalue& r) const
                    {
                        return l.key_ < r.key_;
                    };
                    bool operator()(const rvalue& l, const std::string& r) const
                    {
                        return l.key_ < r;
                    };
                    bool operator()(const std::string& l, const rvalue& r) const
                    {
                        return l < r.key_;
                    };
                };
                if (!is_cached())
                {
                    std::sort(begin(), end(), Pred());
                    set_cached();
                }
                auto it = lower_bound(begin(), end(), str, Pred());
                if (it != end() && it->key_ == str)
                    return *it;
#ifndef CROW_JSON_NO_ERROR_CHECK
                throw std::runtime_error("cannot find key");
#else
                static rvalue nullValue;
                return nullValue;
#endif
            }

            void set_error()
            {
                option_|=error_bit;
            }

            bool error() const
            {
                return (option_&error_bit)!=0;
            }

            std::vector<std::string> keys()
            {
#ifndef CROW_JSON_NO_ERROR_CHECK
                if (t() != type::Object)
                    throw std::runtime_error("value is not an object");
#endif
                std::vector<std::string> ret;
                ret.reserve(lsize_);
                for (uint32_t i = 0; i<lsize_; i++)
                {
                    ret.emplace_back(std::string(l_[i].key()));
                }
                return ret;
            }
        private:
            bool is_cached() const
            {
                return (option_&cached_bit)!=0;
            }
            void set_cached() const
            {
                option_ |= cached_bit;
            }
            void copy_l(const rvalue& r)
            {
                if (r.t() != type::Object && r.t() != type::List)
                    return;
                lsize_ = r.lsize_;
                lremain_ = 0;
                l_.reset(new rvalue[lsize_]);
                std::copy(r.begin(), r.end(), begin());
            }

            void emplace_back(rvalue&& v)
            {
                if (!lremain_)
                {
                    int new_size = lsize_ + lsize_;
                    if (new_size - lsize_ > 60000)
                        new_size = lsize_ + 60000;
                    if (new_size < 4)
                        new_size = 4;
                    rvalue* p = new rvalue[new_size];
                    rvalue* p2 = p;
                    for(auto& x : *this)
                        *p2++ = std::move(x);
                    l_.reset(p);
                    lremain_ = new_size - lsize_;
                }
                l_[lsize_++] = std::move(v);
                lremain_ --;
            }

            /// determines num_type from the string.
            void determine_num_type()
            {
                if (t_ != type::Number)
                {
                    nt_ = num_type::Null;
                    return;
                }

                const std::size_t len = end_ - start_;
                const bool has_minus = std::memchr(start_, '-', len) != nullptr;
                const bool has_e = std::memchr(start_, 'e', len) != nullptr
                                || std::memchr(start_, 'E', len) != nullptr;
                const bool has_dec_sep = std::memchr(start_, '.', len) != nullptr;
                if (has_dec_sep || has_e)
                  nt_ = num_type::Floating_point;
                else if (has_minus)
                  nt_ = num_type::Signed_integer;
                else
                  nt_ = num_type::Unsigned_integer;
            }

            mutable char* start_;
            mutable char* end_;
            detail::r_string key_;
            std::unique_ptr<rvalue[]> l_;
            uint32_t lsize_;
            uint16_t lremain_;
            type t_;
            num_type nt_{num_type::Null};
            mutable uint8_t option_{0};

            friend rvalue load_nocopy_internal(char* data, size_t size);
            friend rvalue load(const char* data, size_t size);
            friend std::ostream& operator <<(std::ostream& os, const rvalue& r)
            {
                switch(r.t_)
                {

                case type::Null: os << "null"; break;
                case type::False: os << "false"; break;
                case type::True: os << "true"; break;
                case type::Number:
                    {
                        switch (r.nt())
                        {
                        case num_type::Floating_point: os << r.d(); break;
                        case num_type::Signed_integer: os << r.i(); break;
                        case num_type::Unsigned_integer: os << r.u(); break;
                        case num_type::Null: throw std::runtime_error("Number with num_type Null");
                        }
                    }
                    break;
                case type::String: os << '"' << r.s() << '"'; break;
                case type::List: 
                    {
                        os << '['; 
                        bool first = true;
                        for(auto& x : r)
                        {
                            if (!first)
                                os << ',';
                            first = false;
                            os << x;
                        }
                        os << ']'; 
                    }
                    break;
                case type::Object:
                    {
                        os << '{'; 
                        bool first = true;
                        for(auto& x : r)
                        {
                            if (!first)
                                os << ',';
                            os << '"' << escape(x.key_) << "\":";
                            first = false;
                            os << x;
                        }
                        os << '}'; 
                    }
                    break;
                }
                return os;
            }
        };
        namespace detail {
        }

        inline bool operator == (const rvalue& l, const std::string& r)
        {
            return l.s() == r;
        }

        inline bool operator == (const std::string& l, const rvalue& r)
        {
            return l == r.s();
        }

        inline bool operator != (const rvalue& l, const std::string& r)
        {
            return l.s() != r;
        }

        inline bool operator != (const std::string& l, const rvalue& r)
        {
            return l != r.s();
        }

        inline bool operator == (const rvalue& l, double r)
        {
            return l.d() == r;
        }

        inline bool operator == (double l, const rvalue& r)
        {
            return l == r.d();
        }

        inline bool operator != (const rvalue& l, double r)
        {
            return l.d() != r;
        }

        inline bool operator != (double l, const rvalue& r)
        {
            return l != r.d();
        }


        inline rvalue load_nocopy_internal(char* data, size_t size)
        {
            //static const char* escaped = "\"\\/\b\f\n\r\t";
            struct Parser
            {
                Parser(char* data, size_t /*size*/)
                    : data(data)
                {
                }

                bool consume(char c)
                {
                    if (crow_json_unlikely(*data != c))
                        return false;
                    data++;
                    return true;
                }

                void ws_skip()
                {
                    while(*data == ' ' || *data == '\t' || *data == '\r' || *data == '\n') ++data;
                };

                rvalue decode_string()
                {
                    if (crow_json_unlikely(!consume('"')))
                        return {};
                    char* start = data;
                    uint8_t has_escaping = 0;
                    while(1)
                    {
                        if (crow_json_likely(*data != '"' && *data != '\\' && *data != '\0'))
                        {
                            data ++;
                        }
                        else if (*data == '"')
                        {
                            *data = 0;
                            *(start-1) = has_escaping;
                            data++;
                            return {type::String, start, data-1};
                        }
                        else if (*data == '\\')
                        {
                            has_escaping = 1;
                            data++;
                            switch(*data)
                            {
                                case 'u':
                                    {
                                        auto check = [](char c)
                                        {
                                            return 
                                                ('0' <= c && c <= '9') ||
                                                ('a' <= c && c <= 'f') ||
                                                ('A' <= c && c <= 'F');
                                        };
                                        if (!(check(*(data+1)) && 
                                            check(*(data+2)) && 
                                            check(*(data+3)) && 
                                            check(*(data+4))))
                                            return {};
                                    }
                                    data += 5;
                                    break;
                                case '"':
                                case '\\':
                                case '/':
                                case 'b':
                                case 'f':
                                case 'n':
                                case 'r':
                                case 't':
                                    data ++;
                                    break;
                                default:
                                    return {};
                            }
                        }
                        else
                            return {};
                    }
                    return {};
                }

                rvalue decode_list()
                {
                    rvalue ret(type::List);
                    if (crow_json_unlikely(!consume('[')))
                    {
                        ret.set_error();
                        return ret;
                    }
                    ws_skip();
                    if (crow_json_unlikely(*data == ']'))
                    {
                        data++;
                        return ret;
                    }

                    while(1)
                    {
                        auto v = decode_value();
                        if (crow_json_unlikely(!v))
                        {
                            ret.set_error();
                            break;
                        }
                        ws_skip();
                        ret.emplace_back(std::move(v));
                        if (*data == ']')
                        {
                            data++;
                            break;
                        }
                        if (crow_json_unlikely(!consume(',')))
                        {
                            ret.set_error();
                            break;
                        }
                        ws_skip();
                    }
                    return ret;
                }

                rvalue decode_number()
                {
                    char* start = data;

                    enum NumberParsingState
                    {
                        Minus,
                        AfterMinus,
                        ZeroFirst,
                        Digits,
                        DigitsAfterPoints,
                        E,
                        DigitsAfterE,
                        Invalid,
                    } state{Minus};
                    while(crow_json_likely(state != Invalid))
                    {
                        switch(*data)
                        {
                            case '0':
                                state = static_cast<NumberParsingState>("\2\2\7\3\4\6\6"[state]);
                                /*if (state == NumberParsingState::Minus || state == NumberParsingState::AfterMinus)
                                {
                                    state = NumberParsingState::ZeroFirst;
                                }
                                else if (state == NumberParsingState::Digits || 
                                    state == NumberParsingState::DigitsAfterE || 
                                    state == NumberParsingState::DigitsAfterPoints)
                                {
                                    // ok; pass
                                }
                                else if (state == NumberParsingState::E)
                                {
                                    state = NumberParsingState::DigitsAfterE;
                                }
                                else
                                    return {};*/
                                break;
                            case '1': case '2': case '3': 
                            case '4': case '5': case '6': 
                            case '7': case '8': case '9':
                                state = static_cast<NumberParsingState>("\3\3\7\3\4\6\6"[state]);
                                while(*(data+1) >= '0' && *(data+1) <= '9') data++;
                                /*if (state == NumberParsingState::Minus || state == NumberParsingState::AfterMinus)
                                {
                                    state = NumberParsingState::Digits;
                                }
                                else if (state == NumberParsingState::Digits || 
                                    state == NumberParsingState::DigitsAfterE || 
                                    state == NumberParsingState::DigitsAfterPoints)
                                {
                                    // ok; pass
                                }
                                else if (state == NumberParsingState::E)
                                {
                                    state = NumberParsingState::DigitsAfterE;
                                }
                                else
                                    return {};*/
                                break;
                            case '.':
                                state = static_cast<NumberParsingState>("\7\7\4\4\7\7\7"[state]);
                                /*
                                if (state == NumberParsingState::Digits || state == NumberParsingState::ZeroFirst)
                                {
                                    state = NumberParsingState::DigitsAfterPoints;
                                }
                                else
                                    return {};
                                */
                                break;
                            case '-':
                                state = static_cast<NumberParsingState>("\1\7\7\7\7\6\7"[state]);
                                /*if (state == NumberParsingState::Minus)
                                {
                                    state = NumberParsingState::AfterMinus;
                                }
                                else if (state == NumberParsingState::E)
                                {
                                    state = NumberParsingState::DigitsAfterE;
                                }
                                else
                                    return {};*/
                                break;
                            case '+':
                                state = static_cast<NumberParsingState>("\7\7\7\7\7\6\7"[state]);
                                /*if (state == NumberParsingState::E)
                                {
                                    state = NumberParsingState::DigitsAfterE;
                                }
                                else
                                    return {};*/
                                break;
                            case 'e': case 'E':
                                state = static_cast<NumberParsingState>("\7\7\7\5\5\7\7"[state]);
                                /*if (state == NumberParsingState::Digits || 
                                    state == NumberParsingState::DigitsAfterPoints)
                                {
                                    state = NumberParsingState::E;
                                }
                                else 
                                    return {};*/
                                break;
                            default:
                                if (crow_json_likely(state == NumberParsingState::ZeroFirst || 
                                        state == NumberParsingState::Digits || 
                                        state == NumberParsingState::DigitsAfterPoints || 
                                        state == NumberParsingState::DigitsAfterE))
                                    return {type::Number, start, data};
                                else
                                    return {};
                        }
                        data++;
                    }

                    return {};
                }

                rvalue decode_value()
                {
                    switch(*data)
                    {
                        case '[':
                            return decode_list();
                        case '{':
                            return decode_object();
                        case '"':
                            return decode_string();
                        case 't':
                            if (//e-data >= 4 &&
                                    data[1] == 'r' &&
                                    data[2] == 'u' &&
                                    data[3] == 'e')
                            {
                                data += 4;
                                return {type::True};
                            }
                            else
                                return {};
                        case 'f':
                            if (//e-data >= 5 &&
                                    data[1] == 'a' &&
                                    data[2] == 'l' &&
                                    data[3] == 's' &&
                                    data[4] == 'e')
                            {
                                data += 5;
                                return {type::False};
                            }
                            else
                                return {};
                        case 'n':
                            if (//e-data >= 4 &&
                                    data[1] == 'u' &&
                                    data[2] == 'l' &&
                                    data[3] == 'l')
                            {
                                data += 4;
                                return {type::Null};
                            }
                            else
                                return {};
                        //case '1': case '2': case '3': 
                        //case '4': case '5': case '6': 
                        //case '7': case '8': case '9':
                        //case '0': case '-':
                        default:
                            return decode_number();
                    }
                    return {};
                }

                rvalue decode_object()
                {
                    rvalue ret(type::Object);
                    if (crow_json_unlikely(!consume('{')))
                    {
                        ret.set_error();
                        return ret;
                    }

                    ws_skip();

                    if (crow_json_unlikely(*data == '}'))
                    {
                        data++;
                        return ret;
                    }

                    while(1)
                    {
                        auto t = decode_string();
                        if (crow_json_unlikely(!t))
                        {
                            ret.set_error();
                            break;
                        }

                        ws_skip();
                        if (crow_json_unlikely(!consume(':')))
                        {
                            ret.set_error();
                            break;
                        }

                        // TODO caching key to speed up (flyweight?)
                        // I have no idea how flyweight could apply here, but maybe some speedup can happen if we stopped checking type since decode_string returns a string anyway
                        auto key = t.s();

                        ws_skip();
                        auto v = decode_value();
                        if (crow_json_unlikely(!v))
                        {
                            ret.set_error();
                            break;
                        }
                        ws_skip();

                        v.key_ = std::move(key);
                        ret.emplace_back(std::move(v));
                        if (crow_json_unlikely(*data == '}'))
                        {
                            data++;
                            break;
                        }
                        if (crow_json_unlikely(!consume(',')))
                        {
                            ret.set_error();
                            break;
                        }
                        ws_skip();
                    }
                    return ret;
                }

                rvalue parse()
                {
                    ws_skip();
                    auto ret = decode_value(); // or decode object?
                    ws_skip();
                    if (ret && *data != '\0')
                        ret.set_error();
                    return ret;
                }

                char* data;
            };
            return Parser(data, size).parse();
        }
        inline rvalue load(const char* data, size_t size)
        {
            char* s = new char[size+1];
            memcpy(s, data, size);
            s[size] = 0;
            auto ret = load_nocopy_internal(s, size);
            if (ret)
                ret.key_.force(s, size);
            else
                delete[] s;
            return ret;
        }

        inline rvalue load(const char* data)
        {
            return load(data, strlen(data));
        }

        inline rvalue load(const std::string& str)
        {
            return load(str.data(), str.size());
        }

        /// JSON write value.

        ///
        /// Value can mean any json value, including a JSON object.
        /// Write means this class is used to primarily assemble JSON objects using keys and values and export those into a string.
        class wvalue : public returnable
        {
            friend class crow::mustache::template_t;
        public:
            type t() const { return t_; }
        private:
            type t_{type::Null}; ///< The type of the value.
            num_type nt{num_type::Null}; ///< The specific type of the number if \ref t_ is a number.
            union {
              double d;
              int64_t si;
              uint64_t ui {};
            } num; ///< Value if type is a number.
            std::string s; ///< Value if type is a string.
            std::unique_ptr<std::vector<wvalue>> l; ///< Value if type is a list.
#ifdef CROW_JSON_USE_MAP
            std::unique_ptr<std::map<std::string, wvalue>> o;
#else
            std::unique_ptr<std::unordered_map<std::string, wvalue>> o; ///< Value if type is a JSON object.
#endif

        public:

            wvalue() : returnable("application/json") {}

            wvalue(std::vector<wvalue>& r) : returnable("application/json")
            {
                t_ = type::List;
                l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                l->reserve(r.size());
                for(auto it = r.begin(); it != r.end(); ++it)
                    l->emplace_back(*it);
            }

            /// Create a write value from a read value (useful for editing JSON strings).
            wvalue(const rvalue& r) : returnable("application/json")
            {
                t_ = r.t();
                switch(r.t())
                {
                    case type::Null:
                    case type::False:
                    case type::True:
                        return;
                    case type::Number:
                        nt = r.nt();
                        if (nt == num_type::Floating_point)
                          num.d = r.d();
                        else if (nt == num_type::Signed_integer)
                          num.si = r.i();
                        else
                          num.ui = r.u();
                        return;
                    case type::String:
                        s = r.s();
                        return;
                    case type::List:
                        l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                        l->reserve(r.size());
                        for(auto it = r.begin(); it != r.end(); ++it)
                            l->emplace_back(*it);
                        return;
                    case type::Object:
#ifdef CROW_JSON_USE_MAP
                        o = std::unique_ptr<std::map<std::string, wvalue>>(new std::map<std::string, wvalue>{});
#else
                        o = std::unique_ptr<std::unordered_map<std::string, wvalue>>(new std::unordered_map<std::string, wvalue>{});
#endif
                        for(auto it = r.begin(); it != r.end(); ++it)
                            o->emplace(it->key(), *it);
                        return;
                }
            }

            wvalue(const wvalue& r) : returnable("application/json")
            {
                t_ = r.t();
                switch(r.t())
                {
                    case type::Null:
                    case type::False:
                    case type::True:
                        return;
                    case type::Number:
                        nt = r.nt;
                        if (nt == num_type::Floating_point)
                          num.d = r.num.d;
                        else if (nt == num_type::Signed_integer)
                          num.si = r.num.si;
                        else
                          num.ui = r.num.ui;
                        return;
                    case type::String:
                        s = r.s;
                        return;
                    case type::List:
                        l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                        l->reserve(r.size());
                        for(auto it = r.l->begin(); it != r.l->end(); ++it)
                            l->emplace_back(*it);
                        return;
                    case type::Object:
#ifdef CROW_JSON_USE_MAP
                        o = std::unique_ptr<std::map<std::string, wvalue>>(new std::map<std::string, wvalue>{});
#else
                        o = std::unique_ptr<std::unordered_map<std::string, wvalue>>(new std::unordered_map<std::string, wvalue>{});
#endif
                        o->insert(r.o->begin(), r.o->end());
                        return;
                }
            }

            wvalue(wvalue&& r) : returnable("application/json")
            {
                *this = std::move(r);
            }

            wvalue& operator = (wvalue&& r)
            {
                t_ = r.t_;
                num = r.num;
                s = std::move(r.s);
                l = std::move(r.l);
                o = std::move(r.o);
                return *this;
            }

            /// Used for compatibility, same as \ref reset()
            void clear()
            {
                reset();
            }

            void reset()
            {
                t_ = type::Null;
                l.reset();
                o.reset();
            }

            wvalue& operator = (std::nullptr_t)
            {
                reset();
                return *this;
            }
            wvalue& operator = (bool value)
            {
                reset();
                if (value)
                    t_ = type::True;
                else
                    t_ = type::False;
                return *this;
            }

            wvalue& operator = (double value)
            {
                reset();
                t_ = type::Number;
                num.d = value;
                nt = num_type::Floating_point;
                return *this;
            }

            wvalue& operator = (unsigned short value)
            {
                reset();
                t_ = type::Number;
                num.ui = value;
                nt = num_type::Unsigned_integer;
                return *this;
            }

            wvalue& operator = (short value)
            {
                reset();
                t_ = type::Number;
                num.si = value;
                nt = num_type::Signed_integer;
                return *this;
            }

            wvalue& operator = (long long value)
            {
                reset();
                t_ = type::Number;
                num.si = value;
                nt = num_type::Signed_integer;
                return *this;
            }

            wvalue& operator = (long value)
            {
                reset();
                t_ = type::Number;
                num.si = value;
                nt = num_type::Signed_integer;
                return *this;
            }

            wvalue& operator = (int value)
            {
                reset();
                t_ = type::Number;
                num.si = value;
                nt = num_type::Signed_integer;
                return *this;
            }

            wvalue& operator = (unsigned long long value)
            {
                reset();
                t_ = type::Number;
                num.ui = value;
                nt = num_type::Unsigned_integer;
                return *this;
            }

            wvalue& operator = (unsigned long value)
            {
                reset();
                t_ = type::Number;
                num.ui = value;
                nt = num_type::Unsigned_integer;
                return *this;
            }

            wvalue& operator = (unsigned int value)
            {
                reset();
                t_ = type::Number;
                num.ui = value;
                nt = num_type::Unsigned_integer;
                return *this;
            }

            wvalue& operator=(const char* str)
            {
                reset();
                t_ = type::String;
                s = str;
                return *this;
            }

            wvalue& operator=(const std::string& str)
            {
                reset();
                t_ = type::String;
                s = str;
                return *this;
            }

            wvalue& operator=(std::vector<wvalue>&& v)
            {
                if (t_ != type::List)
                    reset();
                t_ = type::List;
                if (!l)
                    l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                l->clear();
                l->resize(v.size());
                size_t idx = 0;
                for(auto& x:v)
                {
                    (*l)[idx++] = std::move(x);
                }
                return *this;
            }

            template <typename T>
            wvalue& operator=(const std::vector<T>& v)
            {
                if (t_ != type::List)
                    reset();
                t_ = type::List;
                if (!l)
                    l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                l->clear();
                l->resize(v.size());
                size_t idx = 0;
                for(auto& x:v)
                {
                    (*l)[idx++] = x;
                }
                return *this;
            }

            wvalue& operator[](unsigned index)
            {
                if (t_ != type::List)
                    reset();
                t_ = type::List;
                if (!l)
                    l = std::unique_ptr<std::vector<wvalue>>(new std::vector<wvalue>{});
                if (l->size() < index+1)
                    l->resize(index+1);
                return (*l)[index];
            }

            int count(const std::string& str)
            {
                if (t_ != type::Object)
                    return 0;
                if (!o)
                    return 0;
                return o->count(str);
            }

            wvalue& operator[](const std::string& str)
            {
                if (t_ != type::Object)
                    reset();
                t_ = type::Object;
                if (!o)
#ifdef CROW_JSON_USE_MAP
                        o = std::unique_ptr<std::map<std::string, wvalue>>(new std::map<std::string, wvalue>{});
#else
                        o = std::unique_ptr<std::unordered_map<std::string, wvalue>>(new std::unordered_map<std::string, wvalue>{});
#endif
                return (*o)[str];
            }

            std::vector<std::string> keys() const 
            {
                if (t_ != type::Object) 
                    return {};
                std::vector<std::string> result;
                for (auto& kv:*o) 
                {
                    result.push_back(kv.first);
                }
                return result;
            }

            /// If the wvalue is a list, it returns the length of the list, otherwise it returns 1.
            std::size_t size() const
            {
                if (t_ != type::List)
                    return 1;
                return l->size();
            }

            /// Returns an estimated size of the value in bytes.
            size_t estimate_length() const
            {
                switch(t_)
                {
                    case type::Null: return 4;
                    case type::False: return 5;
                    case type::True: return 4;
                    case type::Number: return 30;
                    case type::String: return 2+s.size()+s.size()/2;
                    case type::List: 
                        {
                            size_t sum{};
                            if (l)
                            {
                                for(auto& x:*l)
                                {
                                    sum += 1;
                                    sum += x.estimate_length();
                                }
                            }
                            return sum+2;
                        }
                    case type::Object:
                        {
                            size_t sum{};
                            if (o)
                            {
                                for(auto& kv:*o)
                                {
                                    sum += 2;
                                    sum += 2+kv.first.size()+kv.first.size()/2;
                                    sum += kv.second.estimate_length();
                                }
                            }
                            return sum+2;
                        }
                }
                return 1;
            }

        private:

            inline void dump_string(const std::string& str, std::string& out) const
            {
                out.push_back('"');
                escape(str, out);
                out.push_back('"');
            }

            inline void dump_internal(const wvalue& v, std::string& out) const
            {
                switch(v.t_)
                {
                    case type::Null: out += "null"; break;
                    case type::False: out += "false"; break;
                    case type::True: out += "true"; break;
                    case type::Number:
                        {
                            if (v.nt == num_type::Floating_point)
                            {
    #ifdef _MSC_VER
    #define MSC_COMPATIBLE_SPRINTF(BUFFER_PTR, FORMAT_PTR, VALUE) sprintf_s((BUFFER_PTR), 128, (FORMAT_PTR), (VALUE))
    #else
    #define MSC_COMPATIBLE_SPRINTF(BUFFER_PTR, FORMAT_PTR, VALUE) sprintf((BUFFER_PTR), (FORMAT_PTR), (VALUE))
    #endif
                                char outbuf[128];
                                MSC_COMPATIBLE_SPRINTF(outbuf, "%g", v.num.d);
                                out += outbuf;
    #undef MSC_COMPATIBLE_SPRINTF
                            }
                            else if (v.nt == num_type::Signed_integer)
                            {
                                out += std::to_string(v.num.si);
                            }
                            else
                            {
                                out += std::to_string(v.num.ui);
                            }
                        }
                        break;
                    case type::String: dump_string(v.s, out); break;
                    case type::List:
                         {
                             out.push_back('[');
                             if (v.l)
                             {
                                 bool first = true;
                                 for(auto& x:*v.l)
                                 {
                                     if (!first)
                                     {
                                         out.push_back(',');
                                     }
                                     first = false;
                                     dump_internal(x, out);
                                 }
                             }
                             out.push_back(']');
                         }
                         break;
                    case type::Object:
                         {
                             out.push_back('{');
                             if (v.o)
                             {
                                 bool first = true;
                                 for(auto& kv:*v.o)
                                 {
                                     if (!first)
                                     {
                                         out.push_back(',');
                                     }
                                     first = false;
                                     dump_string(kv.first, out);
                                     out.push_back(':');
                                     dump_internal(kv.second, out);
                                 }
                             }
                             out.push_back('}');
                         }
                         break;
                }
            }

        public:
            std::string dump() const
            {
                std::string ret;
                ret.reserve(estimate_length());
                dump_internal(*this, ret);
                return ret;
            }

        };



        //std::vector<boost::asio::const_buffer> dump_ref(wvalue& v)
        //{
        //}
    }
}

#undef crow_json_likely
#undef crow_json_unlikely