src/json.cpp - master - zOMGdev/cppcms

src/json.cpp
1 356 строк28 KB
Artyom Beilis
Fixed incorrect assignment operator
18 авг 2020, 09:11
18 авг 2020, 09:11907213d
///////////////////////////////////////////////////////////////////////////////
//                                                                             
//  Copyright (C) 2008-2012  Artyom Beilis (Tonkikh) <artyomtnk@yahoo.com>     
//                                                                             
//  See accompanying file COPYING.TXT file for licensing details.
//
///////////////////////////////////////////////////////////////////////////////
#define CPPCMS_SOURCE
#include <cppcms/json.h>
#include <sstream>
#include <stdio.h>
#include <typeinfo>
#include <algorithm>
#include <iostream>
#include <locale>
#include <limits>
#include <iomanip>
#include <stdexcept>
#include <stack>
#include "utf_iterator.h"

namespace cppcms {
namespace json {

	static const size_t json_max_depth = 512;

	bad_value_cast::bad_value_cast() : msg_("cppcms::json::bad_cast") 
	{
	}
	bad_value_cast::bad_value_cast(std::string const &s) : msg_("cppcms::json::bad_cast: "+s ) 
	{
	}
	bad_value_cast::bad_value_cast(std::string const &s,json_type actual) : 
		msg_("cppcms::json::bad_cast: " + s)
	{
		std::ostringstream msg;
		msg<<" error converting from "<<actual;
		msg_ +=msg.str();

	}
	bad_value_cast::bad_value_cast(std::string const &s,json_type expected, json_type actual) : 
		msg_("cppcms::json::bad_cast: " + s)
	{
		std::ostringstream msg;
		msg<<" error converting from "<<actual<<" to "<<expected;
		msg_ +=msg.str();

	}
	bad_value_cast::~bad_value_cast() throw()
	{
	}
	const char* bad_value_cast::what() const throw()
	{
		return msg_.c_str();
	}

	template<typename T>
	struct json_type_traits;
	template<>
	struct json_type_traits<undefined> { static const json_type type=is_undefined; };
	template<>
	struct json_type_traits<null> { static const json_type type=is_null; };
	template<>
	struct json_type_traits<bool> { static const json_type type=is_boolean; };
	template<>
	struct json_type_traits<double> { static const json_type type=is_number; };
	template<>
	struct json_type_traits<array> { static const json_type type=is_array; };
	template<>
	struct json_type_traits<object> { static const json_type type=is_object; };
	template<>
	struct json_type_traits<std::string> { static const json_type type=is_string; };

	template<json_type t>
	struct cpp_type_traits;

	template<> struct cpp_type_traits<is_boolean> { typedef bool type; };
	template<> struct cpp_type_traits<is_number> { typedef double type; };
	template<> struct cpp_type_traits<is_string> { typedef std::string type; };
	template<> struct cpp_type_traits<is_array> { typedef array type; };
	template<> struct cpp_type_traits<is_object> { typedef object type; };

	class variant {
	public:
		union memory {
			void *p;
			bool bv;
			double dv;
			char s[sizeof(std::string)];
			char a[sizeof(json::array)];
			char o[sizeof(json::object)];
		} m;

		void *ptr()
		{
			return static_cast<void *>(&m);
		}
		void const *ptr() const
		{
			return static_cast<void const *>(&m);
		}

		json_type which() const 
		{
			return type;
		}

		json_type type;

		bool operator==(variant const &other) const
		{
			if(type != other.type)
				return false;
			switch(type) {
			case is_boolean:
				return get<bool>() == other.get<bool>();
			case is_number:
				return get<double>() == other.get<double>();
			case is_string:
				return get<std::string>() == other.get<std::string>();
			case is_object:
				return get<object>() == other.get<object>();
			case is_array:
				return get<array>() == other.get<array>();
			default:
				return true;
			}
		}

		variant()
		{
			create(is_undefined);
		}

		~variant()
		{
			destroy();
		}

		variant(variant const &other) 
		{
			create(other.type,other.m);
		}
		variant &operator=(variant const &other) 
		{
			if(this!=&other) {
				destroy();
				create(other.type,other.m);
			}
			return *this;
		}

		template<typename T>
		T &get()
		{
			json_type expected = json_type_traits<T>::type;
			if(expected != type) 
				throw bad_value_cast("invalid type",expected,type);
			switch(type) {
			case is_undefined:
			case is_null:
				throw bad_value_cast("non-fetchable type",type);
			default:
				return *static_cast<T *>(ptr());
			}
		}
		template<typename T>
		T const &get() const
		{
			json_type expected = json_type_traits<T>::type;
			if(expected != type) 
				throw bad_value_cast("invalid type",expected,type);
			switch(type) {
			case is_undefined:
			case is_null:
				throw bad_value_cast("non-fetchable type",type);
			default:
				return *static_cast<T const *>(ptr());
			}
		}

		template<typename T>
		variant(T const &v)
		{
			create<T>(v);
		}

		template<typename T>
		variant &operator=(T const &other)
		{
			destroy();
			create<T>(other);
			return *this;
		}

		template<typename T>
		void create(T const &v)
		{
			void *p=ptr();
			type = json_type_traits<T>::type;
			switch(type) {
			case is_undefined:
			case is_null:
			case is_boolean:
			case is_number:
				memcpy(&m,&v,sizeof(T));
				break;
			case is_string:
				new(p) std::string(reinterpret_cast<std::string const &>(v));
				break;
			case is_object:
				new(p) object(reinterpret_cast<object const &>(v));
				break;
			case is_array:
				new(p) array(reinterpret_cast<array const &>(v));
				break;
			}
		}
		
		void create(json_type t)
		{
			type = t;
			memset(ptr(),0,sizeof(m));
			switch(type) {
			case is_undefined:
			case is_null:
			case is_boolean:
			case is_number:
				break;
			case is_string:
				new(ptr()) std::string();
				break;
			case is_object:
				new(ptr()) object();
				break;
			case is_array:
				new(ptr()) array();
				break;
			}
		}
		void create(json_type t,memory const &other)
		{
			void *p=&m;
			type = t;
			switch(t) {
			case is_undefined:
			case is_null:
			case is_boolean:
			case is_number:
				memcpy(&m,&other,sizeof(m));
				break;
			case is_string:
				new(p) std::string(reinterpret_cast<std::string const &>(other));
				break;
			case is_object:
				new(p) object(reinterpret_cast<object const &>(other));
				break;
			case is_array:
				new(p) array(reinterpret_cast<array const &>(other));
				break;
			}
		}
		void destroy()
		{
			typedef std::string string_type;
			switch(type) {
			case is_undefined:
			case is_null:
			case is_boolean:
			case is_number:
				break;
			case is_string:
				static_cast<string_type *>(ptr())->~string_type();
				break;
			case is_object:
				static_cast<object *>(ptr())->~object();
				break;
			case is_array:
				static_cast<array *>(ptr())->~array();
				break;
			}
			memset(&m,0,sizeof(m));
		}
	};

	typedef variant variant_type;

	struct value::_data {
	public:
		variant_type &value()
		{
			return value_;			
		}

		variant_type const &value() const
		{
			return value_;
			
		}
	private:
		variant_type value_;
	};
	using namespace std;
	
	value::copyable::copyable() :
		d(new value::_data()) 
	{
	}
	value::copyable::~copyable()
	{
	}
	value::copyable::copyable(copyable const &r) : 
		d(r.d) 
	{
	}

	value::copyable &value::copyable::operator=(value::copyable &&r)
	{
		d.swap(r.d);
		return *this;
	}
	value::copyable::copyable(value::copyable &&r) : d(new value::_data())
	{
		d.swap(r.d);
	}
	value::copyable const &value::copyable::operator=(value::copyable const &r)
	{
		if(&r!=this)
			d=r.d;
		return *this;
	}

	double const &value::number() const
	{
		return d->value().get<double>();
	}
	bool const &value::boolean() const
	{
		return d->value().get<bool>();
	}
	std::string const &value::str() const
	{
		return d->value().get<std::string>();
	}

	json::object const &value::object() const
	{
		return d->value().get<json::object>();
	}
	json::array const &value::array() const
	{
		return d->value().get<json::array>();
	}
	double &value::number() 
	{
		return d->value().get<double>();
	}
	bool &value::boolean()
	{
		return d->value().get<bool>();
	}
	std::string &value::str()
	{
		return d->value().get<std::string>();
	}

	json::object &value::object()
	{
		return d->value().get<json::object>();
	}
	json::array &value::array()
	{
		return d->value().get<json::array>();
	}

	bool value::is_undefined() const
	{
		return d->value().which()==json::is_undefined;
	}
	bool value::is_null() const
	{
		return d->value().which()==json::is_null;
	}


	void value::undefined()
	{
		d->value()=json::undefined();
	}
	void value::null()
	{
		d->value()=json::null();
	}
	void value::boolean(bool x)
	{
		d->value()=x;
	}
	void value::number(double x)
	{
		d->value()=x;
	}
	void value::str(std::string const &x)
	{
		d->value()=x;
	}
	void value::object(json::object const &x)
	{
		d->value()=x;
	}
	void value::array(json::array const &x)
	{
		d->value()=x;
	}

	json_type value::type() const
	{
		return d->value().which();
	}
	namespace details {
	
		template<typename Appender>
		void generic_append(char const *begin,char const *end,Appender &a)
		{
			a.append('"');
			char const *i,*last;
			char buf[8] = "\\u00";
			for(i=begin,last = begin;i!=end;) {
				char const *addon = 0;
				unsigned char c=*i;
				switch(c) {
				case 0x22: addon = "\\\""; break;
				case 0x5C: addon = "\\\\"; break;
				case '\b': addon = "\\b"; break;
				case '\f': addon = "\\f"; break;
				case '\n': addon = "\\n"; break;
				case '\r': addon = "\\r"; break;
				case '\t': addon = "\\t"; break;
				default:
					if(c<=0x1F) {
						static char const tohex[]="0123456789abcdef";
						buf[4]=tohex[c >>  4];
						buf[5]=tohex[c & 0xF];
						buf[6]=0;
						addon = buf;
					}
				};
				if(addon) {
					a.append(last,i-last);
					a.append(addon);
					i++;
					last = i;
				}
				else {
					i++;
				}
			}
			a.append(last,i-last);
			a.append('"');
		}

		struct string_append {
			std::string *out;
			void append(char c) { *out += c; }
			void append(char const *s,size_t n) { out->append(s,n); }
			void append(char const *s) { out->append(s); }
		};

		struct stream_append {
			std::ostream *out;
			void append(char c) { *out << c; }
			void append(char const *s,size_t n) { out->write(s,n); }
			void append(char const *s) { *out << s; }
		};
	
	}

	std::string CPPCMS_API to_json(char const *begin,char const *end)
	{
		std::string result;
		result.reserve(end-begin + 2);
		details::string_append ap = { &result };
		details::generic_append(begin,end,ap);
		return result;
	}
	std::string CPPCMS_API to_json(std::string const &s)
	{
		return to_json(s.c_str(),s.c_str()+s.size());
	}
	void CPPCMS_API to_json(char const *begin,char const *end,std::ostream &out)
	{
		details::stream_append ap = { &out };
		details::generic_append(begin,end,ap);
	}
	void CPPCMS_API to_json(std::string const &str,std::ostream &out)
	{
		to_json(str.c_str(),str.c_str()+str.size(),out);
	}

	namespace {

		void pad(std::ostream &out,int tb)
		{
			for(;tb > 0;tb--) out<<'\t';
		}

		void indent(std::ostream &out,char c,int &tabs)
		{
			if(tabs < 0) {
				out<<c;
				return;
			}
			switch(c) {
			case '{':
			case '[':
				out<<c<<'\n';
				tabs++;
				pad(out,tabs);
				break;
			case ',':
				out<<c<<'\n';
				pad(out,tabs);
				break;
			case ':':
				out<<" :\t";
				break;
			case '}':
			case ']':
				out<<'\n';
				tabs--;
				pad(out,tabs);
				out<<c<<'\n';
				pad(out,tabs);
				break;
			}
		}

	} // namespace anonymous


	void value::write(std::ostream &out,int tabs) const
	{
		std::locale original(out.getloc());
		out.imbue(std::locale("C"));
		try {
			write_value(out,tabs);
		}
		catch(...) {
			out.imbue(original);
			throw;
		}
		out.imbue(original);

	}

	void value::write_value(std::ostream &out,int tabs) const
	{
		switch(type()) {
		case json::is_undefined:
			throw bad_value_cast("Can't write undefined value to stream");
		case json::is_null:
			out<<"null";
			break;
		case json::is_number:
			out<<std::setprecision(std::numeric_limits<double>::digits10+1)<<number();
			break;
		case json::is_string:
			to_json(str(),out);
			break;
		case json::is_boolean:
			out<< (boolean() ? "true" : "false") ;
			break;
		case json::is_array:
			{
				json::array const &a=array();
				unsigned i;
				indent(out,'[',tabs);
				for(i=0;i<a.size();) {
					a[i].write_value(out,tabs);
					i++;
					if(i<a.size())
						indent(out,',',tabs);
				}
				indent(out,']',tabs);
			}
			break;
		case json::is_object:
			{
				json::object const &obj=object();
				object::const_iterator p,end;
				p=obj.begin();
				end=obj.end();
				indent(out,'{',tabs);
				while(p!=end) {
					to_json(p->first.begin(),p->first.end(),out);
					indent(out,':',tabs);
					p->second.write_value(out,tabs);
					++p;
					if(p!=end)
						indent(out,',',tabs);
				}
				indent(out,'}',tabs);
			}
			break;
		default:
			throw bad_value_cast("Unknown type found: internal error");
		}
	}

	void value::save(std::ostream &out,int how) const
	{
		int tabs=(how & readable) ? 0 : -1;
		write(out,tabs);
	}
	
	std::string value::save(int how) const
	{
		std::ostringstream ss;
		int tabs=(how & readable) ? 0 : -1;
		write(ss,tabs);
		return ss.str();
	}

	std::ostream &operator<<(std::ostream &out,value const &v)
	{
		v.save(out);
		return out;
	}

	bool value::operator==(value const &other) const
	{
		return d->value()==other.d->value();
	}
	bool value::operator!=(value const &other) const
	{
		return !(*this==other);
	}


	// returns empty if not found
	value const &value::find(char const *cpath) const
	{
		string_key path=string_key::unowned(cpath);
		static value const empty;
		value const *ptr=this;
		size_t pos=0;
		size_t new_pos;
		do {
			new_pos=path.find('.',pos);
			string_key const part=path.unowned_substr(pos,new_pos - pos);
			if(new_pos!=std::string::npos)
				new_pos++;
			if(part.empty())
				return empty;
			if(ptr->type()!=json::is_object)
				return empty;
			json::object const &obj=ptr->object();
			json::object::const_iterator p;
			if((p=obj.find(part))==obj.end())
				return empty;
			ptr=&p->second;
			pos=new_pos;

		} while(new_pos < path.size());
		return *ptr;
	}
	// returns empty if not found
	value const &value::find(std::string const &path) const
	{
		return find(path.c_str());
	}
	
	// throws if not found
	value const &value::at(std::string const &path) const
	{
		return at(path.c_str());
	}
	value const &value::at(char const *path) const
	{
		value const &v=find(path);
		if(v.is_undefined())
			throw bad_value_cast(std::string("Value not found at ")+path );
		return v;
	}
	value &value::at(std::string const &path)
	{
		return at(path.c_str());
	}
	value &value::at(char const *cpath)
	{
		string_key path=string_key::unowned(cpath);
		value *ptr=this;
		size_t pos=0;
		size_t new_pos;
		do {
			new_pos=path.find('.',pos);
			string_key part=path.unowned_substr(pos,new_pos - pos);
			if(new_pos!=std::string::npos)
				new_pos++;
			if(part.empty())
				throw bad_value_cast("Invalid path provided");
			if(ptr->type()!=json::is_object)
				throw bad_value_cast("",ptr->type(),json::is_object);
			json::object &obj=ptr->object();
			json::object::iterator p;
			if((p=obj.find(part))==obj.end())
				throw bad_value_cast("Member "+part.str()+" not found");
			ptr=&p->second;
			pos=new_pos;

		} while(new_pos < path.size());
		return *ptr;
	}
	void value::at(std::string const &path,value const &v)
	{
		at(path.c_str(),v);
	}
	void value::at(char const *cpath,value const &v)
	{
		string_key path=string_key::unowned(cpath);
		value *ptr=this;
		size_t pos=0;
		size_t new_pos;
		do {
			new_pos=path.find('.',pos);
			string_key part=path.unowned_substr(pos,new_pos - pos);


			if(new_pos!=std::string::npos)
				new_pos++;
			if(part.empty())
				throw bad_value_cast("Invalid path provided");
			if(ptr->type()!=json::is_object) {
				*ptr=json::object();
			}
			json::object &obj=ptr->object();
			json::object::iterator p;
			if((p=obj.find(part))==obj.end()) {
				ptr=&obj.insert(std::make_pair(part.str(),json::value())).first->second;
			}
			else
				ptr=&p->second;
			pos=new_pos;

		} while(new_pos < path.size());
		*ptr=v;
	}

	value &value::operator[](std::string const &name)
	{
		if(type()!=json::is_object)
			set_value(json::object());

		json::object &self=object();

		json::object::iterator p=self.find(string_key::unowned(name));
		if(p==self.end())
			return self.insert(std::make_pair(name,value())).first->second;
		return p->second;
	}

	value const &value::operator[](std::string const &name) const
	{
		if(type()!=json::is_object)
			throw bad_value_cast("",type(),json::is_object);
		json::object const &self=object();
		json::object::const_iterator p=self.find(string_key::unowned(name));
		if(p==self.end())
			throw bad_value_cast("Member "+name+" not found");
		return p->second;
	}

	value &value::operator[](size_t n)
	{
		if(type()!=json::is_array)
			set_value(json::array());
		json::array &self=array();
		if(n>=self.size())
			self.resize(n+1,json::null());
		return self[n];
	}
	
	value const &value::operator[](size_t n) const
	{
		if(type()!=json::is_array)
			throw bad_value_cast("",type(),json::is_array);
		if(n >= array().size())
			throw bad_value_cast("Index out of range");
		return array()[n];
	}

//#define DEBUG_PARSER


	namespace {

		enum {	
			tock_eof = 255,
			tock_err,
			tock_str,
			tock_number,
			tock_true,
			tock_false,
			tock_null 
		};


		struct tockenizer {
		public:
			tockenizer(std::istream &in) : 
				real(0),
				line(1),
				is_(in),
				locale_(in.getloc())
			{
				is_.imbue(std::locale::classic());
			}
			~tockenizer()
			{
				is_.imbue(locale_);
			}

			std::string str;
			double real;
			int line;
#ifdef DEBUG_PARSER
			std::string write_tocken(int c)
			{
				std::ostringstream ss;
				if(c>=255) {
					static char const *name[] = {
						"eof",
						"err",
						"str",
						"number",
						"true",
						"false",
						"null"
					};
					ss<<name[c - 255];
				}
				else {
					ss<<char(c);
				}
				if(c==tock_str)
					ss<<" "<<str;
				else if(c==tock_number)
					ss<<" "<<real;
				return ss.str();

			}
#endif

			int next()
			{
				std::streambuf *buf = is_.rdbuf();
				for(;;) {
					int c;
					if((c=buf->sbumpc())==-1)
						return tock_eof;
					switch(c) {
					case '[':
					case '{':
					case ':':
					case ',':
					case '}':
					case ']':
						return c;
					case ' ':
					case '\t':
					case '\r':
						break;
					case '\n':
						line++;
						break;
					case '"':
						buf->sungetc();
						if(parse_string())
							return tock_str;
						return tock_err;
					case 't':
						if(check("rue"))
							return tock_true;
						return tock_err;
					case 'n':
						if(check("ull"))
							return tock_null;
						return tock_err;
					case 'f':
						if(check("alse"))
							return tock_false;
						return tock_err;
					case '-':
					case '0':
					case '1':
					case '2':
					case '3':
					case '4':
					case '5':
					case '6':
					case '7':
					case '8':
					case '9':
						buf->sungetc();
						if(parse_number())
							return tock_number;
						return tock_err;
					case '/':
						if(check("/")) {
							while((c=buf->sbumpc())!=-1 && c!='\n')
								;
							if(c=='\n')
								break;
							return tock_eof;
						}
						return tock_err;
					default:
						return tock_err;
					}
				}
			}
		private:
			std::istream &is_;
			std::locale locale_;

			bool check(char const *s)
			{
				std::streambuf *buf = is_.rdbuf();
				while(*s && buf->sbumpc()==std::char_traits<char>::to_int_type(*s))
					s++;
				return *s==0;
			}
			bool parse_string()
			{
				int c;
				std::streambuf *buf=is_.rdbuf();
				str.clear();
				if((c=buf->sbumpc())==-1 || c!='"')
					return false;
				bool second_surragate_expected=false;
				uint16_t first_surragate = 0;
				for(;;) {
					if((c=buf->sbumpc())==-1)
						return false;
					if(second_surragate_expected && c!='\\')
						return false;
					if(0<= c && c <= 0x1F)
						return false;
					if(c=='"')
						break;
					if(c=='\\') {
						if((c=buf->sbumpc())==-1)
							return false;
						if(second_surragate_expected && c!='u')
							return false;

						switch(c) {
						case	'"':
						case	'\\':
						case	'/':
							str+=char(c);
							break;

						case	'b': str+='\b'; break;
						case	'f': str+='\f'; break;
						case	'n': str+='\n'; break;
						case	'r': str+='\r'; break; 
						case	't': str+='\t'; break;
						case	'u': 
							{
								uint16_t x;
								if(!read_4_digits(x))
									return false;
								if(second_surragate_expected) {
									if(!utf16::is_second_surrogate(x))
										return false;
									append(utf16::combine_surrogate(first_surragate,x));
									second_surragate_expected=false;
								}
								else if(utf16::is_first_surrogate(x)) {
									second_surragate_expected=true;
									first_surragate=x;
								}
								else {
									append(x);
								}
								
							}
							break;
						default:
							return false;
						}
					}
					else {
						str+=char(c);
					}
				}
				if(!utf8::validate(str.begin(),str.end()))
					return false;
				return true;
			}

			bool read_4_digits(uint16_t &x)
			{
				char buf[5]={0};
				if(!is_.get(buf,5))
					return false;
				for(unsigned i=0;i<4;i++) {

					char c=buf[i];

					if(	('0'<= c && c<='9')
						|| ('A'<= c && c<='F')
						|| ('a'<= c && c<='f') )
					{
						continue;
					}
					return false;
				}
				unsigned v;
				sscanf(buf,"%x",&v);
				x=v;
				return true;
			}

			void append(uint32_t x)
			{
				utf8::seq s=utf8::encode(x);
				str.append(s.c,s.len);
			}


			bool parse_number()
			{
				is_ >> real;
				return !is_.fail();;
			}
			
		};

		typedef enum {
			st_init = 0,
			st_object_or_array_or_value_expected = 0 ,
			st_object_key_or_close_expected,
			st_object_colon_expected,
			st_object_value_expected,
			st_object_close_or_comma_expected,
			st_array_value_or_close_expected,
			st_array_close_or_comma_expected,
			st_error,
			st_done
		} state_type;

#ifdef DEBUG_PARSER
		std::ostream &operator<<(std::ostream &out,state_type t)
		{
			static char const *names[] = {
				"st_object_or_array_or_value_expected",
				"st_object_key_or_close_expected",
				"st_object_colon_expected",
				"st_object_value_expected",
				"st_object_close_or_comma_expected",
				"st_array_value_or_close_expected",
				"st_array_close_or_comma_expected",
				"st_error",
				"st_done"
			};
			out<<names[t];
			return out;
		}
#endif

		class charbuf : public std::streambuf {
		public:
			charbuf(char const *begin,char const *end)
			{
				setg(const_cast<char *>(begin),const_cast<char *>(begin),const_cast<char *>(end));
			}
			char const *position()
			{
				return gptr();
			}
		};
		
		bool parse_stream(std::istream &in,value &out,bool force_eof,int &error_at_line);
		bool parse_stream(char const *&begin,char const *end,value &out,bool force_eof,int &error_at_line)
		{
			charbuf b(begin,end);
			std::istream is(&b);
			bool r=parse_stream(is,out,force_eof,error_at_line);
			begin = b.position();
			return r;
		}

		bool parse_stream(std::istream &in,value &out,bool force_eof,int &error_at_line)
		{
			tockenizer tock(in);
			value result;
		
			state_type state=st_init;
			
			std::string key;

			std::stack<std::pair<state_type,value *> > stack;

			stack.push(std::make_pair(st_done,&result));

			while(!stack.empty() && state !=st_error && state!=st_done && stack.size() <= json_max_depth) {

				int c=tock.next();
#ifdef DEBUG_PARSER
				std::cout<<state<<" "<<tock.write_tocken(c)<<std::endl;
#endif

				switch(state) {
				case st_object_or_array_or_value_expected:
					if(c=='[')  {
						*stack.top().second=json::array();
						state=st_array_value_or_close_expected;
					}
					else if(c=='{') {
						*stack.top().second=json::object();
						state=st_object_key_or_close_expected;
					}
					else if(c==tock_str)  {
						*stack.top().second=tock.str; 
						state=stack.top().first;
						stack.pop();
					}
					else if(c==tock_true) {
						*stack.top().second=true;
						state=stack.top().first;
						stack.pop();
					}
					else if(c==tock_false) {
						*stack.top().second=false;
						state=stack.top().first;
						stack.pop();
					}
					else if(c==tock_null) {
						*stack.top().second=null();
						state=stack.top().first;
						stack.pop();
					}
					else if(c==tock_number) {
						*stack.top().second=tock.real;
						state=stack.top().first;
						stack.pop();
					}
					else
						state = st_error;
					break;

				case st_object_key_or_close_expected:
					if(c=='}') {
						state=stack.top().first;
						stack.pop();
					}
					else if (c==tock_str) {
						key=tock.str;
						state = st_object_colon_expected;
					}
					else
						state = st_error;
					break;
				case st_object_colon_expected:
					if(c!=':')
						state=st_error;
					else
						state=st_object_value_expected;
					break;
				case st_object_value_expected:
					{
						json::object &obj = stack.top().second->object();
						std::pair<json::object::iterator,bool> res=
							obj.insert(std::make_pair(key,json::value()));

						if(res.second==false) {
							state=st_error;
							break;
						}
						json::value &val=res.first->second;

						if(c==tock_str) { 
							val=tock.str;
							state=st_object_close_or_comma_expected;
						}
						else if(c==tock_true) {
							val=true;
							state=st_object_close_or_comma_expected;
						}
						else if(c==tock_false) {
							val=false;
							state=st_object_close_or_comma_expected;
						}
						else if(c==tock_null) {
							val=null();
							state=st_object_close_or_comma_expected;
						}
						else if(c==tock_number) {
							val=tock.real;
							state=st_object_close_or_comma_expected;
						}
						else if(c=='[') {
							val=json::array();
							state=st_array_value_or_close_expected;
							stack.push(std::make_pair(st_object_close_or_comma_expected,&val));
						}
						else if(c=='{') {
							val=json::object();
							state=st_object_key_or_close_expected;
							stack.push(std::make_pair(st_object_close_or_comma_expected,&val));
						}
						else 
							state=st_error;
					}
					break;
				case st_object_close_or_comma_expected:
					if(c==',')
						state=st_object_key_or_close_expected;
					else if(c=='}') {
						state=stack.top().first;
						stack.pop();
					}
					else
						state=st_error;
					break;
				case st_array_value_or_close_expected:
					{
						if(c==']') {
							state=stack.top().first;
							stack.pop();
							break;
						}

						json::array &ar = stack.top().second->array();
						ar.push_back(json::value());
						json::value &val=ar.back();

						if(c==tock_str)  {
							val=tock.str; 
							state=st_array_close_or_comma_expected;
						}
						else if(c==tock_true) {
							val=true;
							state=st_array_close_or_comma_expected;
						}
						else if(c==tock_false) {
							val=false;
							state=st_array_close_or_comma_expected;
						}
						else if(c==tock_null) {
							val=null();
							state=st_array_close_or_comma_expected;
						}
						else if(c==tock_number) {
							val=tock.real;
							state=st_array_close_or_comma_expected;
						}
						else if(c=='[') {
							val=json::array();
							state=st_array_value_or_close_expected;
							stack.push(std::make_pair(st_array_close_or_comma_expected,&val));
						}
						else if(c=='{') {
							val=json::object();
							state=st_object_key_or_close_expected;
							stack.push(std::make_pair(st_array_close_or_comma_expected,&val));
						}
						else 
							state=st_error;
						break;
					}
				case st_array_close_or_comma_expected:
					if(c==']') {
						state=stack.top().first;
						stack.pop();
					}
					else if(c==',')
						state=st_array_value_or_close_expected;
					else
						state=st_error;
					break;
				case st_done:
				case st_error:
					break;

				};
			}
			if(state==st_done) { 
				if(force_eof) {
					if(tock.next()!=tock_eof) {
						error_at_line=tock.line;
						return false;
					}
				}
				out.swap(result);
				return true;
			}
			error_at_line=tock.line;
			return false;

		}
	} // anonymous

	bool value::load(std::istream &in,bool full,int *line_number)
	{
		int err_line;
		if(!parse_stream(in,*this,full,err_line)) {
			if(line_number)
				*line_number=err_line;
			return false;
		}
		return true;

	}
	bool value::load(char const *&begin,char const *end,bool full,int *line_number)
	{
		int err_line;
		if(!parse_stream(begin,end,*this,full,err_line)) {
			if(line_number)
				*line_number=err_line;
			return false;
		}
		return true;

	}
	
	std::istream &operator>>(std::istream &in,value &v)
	{
		int line_no;
		if(!parse_stream(in,v,false,line_no))
			in.setstate( std::istream::failbit );
		return in;
	}
	
	std::ostream &operator<<(std::ostream &out,json_type t)
	{
		switch(t) {
		case is_undefined: out<<"undefined"; break;
		case is_null: out<<"null"; break;
		case is_boolean: out<<"boolean"; break;
		case is_number: out<<"number"; break;
		case is_string: out<<"string"; break;
		case is_object: out<<"object"; break;
		case is_array: out<<"array"; break;
		default:
			out<<"Illegal";
		}
		return out;
	}



} // json

} // cppcms