path: root/protocols/Twitter/tinyjson.hpp

/*
 * TinyJson 1.3.0
 * A Minimalistic JSON Reader Based On Boost.Spirit, Boost.Any, and Boost.Smart_Ptr.
 *
 * Copyright (c) 2008 Thomas Jansen (thomas@beef.de)
 *
 * Distributed under the Boost Software License, Version 1.0. (See accompanying
 * file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 *
 * See http://blog.beef.de/projects/tinyjson/ for documentation.
 *
 * (view source with tab-size = 3)
 *
 * 16 Mar 2009 - allow root of JSON to be array (Jim Porter)
 * 29 Mar 2008 - use strict_real_p for number parsing, small cleanup (Thomas Jansen)
 * 26 Mar 2008 - made json::grammar a template (Boris Schaeling)
 * 20 Mar 2008 - optimized by using boost::shared_ptr (Thomas Jansen)
 * 29 Jan 2008 - Small bugfixes (Thomas Jansen)
 * 04 Jan 2008 - Released to the public (Thomas Jansen)
 * 13 Nov 2007 - initial release (Thomas Jansen) *
 *
 * 29 Mar 2008
 */


#ifndef	TINYJSON_HPP
#define	TINYJSON_HPP

#include	<boost/shared_ptr.hpp>
#include	<boost/any.hpp>
#include	<boost/spirit/core.hpp>
#include	<boost/spirit/utility/loops.hpp>
#include	<boost/lexical_cast.hpp>

#include	<string>
#include	<stack>
#include	<utility>
#include	<deque>
#include	<map>


namespace json
{
	boost::spirit::int_parser<long long> const
        longlong_p   = boost::spirit::int_parser<long long>();

	// ==========================================================================================================
	// ===                                    U N I C O D E _ C O N V E R T                                   ===
	// ==========================================================================================================

	template< typename Char >
	struct unicodecvt
	{
		static std::basic_string< Char > convert(int iUnicode)
		{
			return std::basic_string< Char >(1, static_cast< Char >(iUnicode));
		}
	};


	// ---[ TEMPLATE SPECIALIZATION FOR CHAR ]--------------------------------------------------------------------

	template<>
	struct unicodecvt< char >
	{
		static std::string convert(int iUnicode)
		{
			std::string strString;

			if (iUnicode < 0x0080)
			{
				// character 0x0000 - 0x007f...

				strString.push_back(0x00 | ((iUnicode & 0x007f) >> 0));
			}
			else if (iUnicode < 0x0800)
			{
				// character 0x0080 - 0x07ff...

				strString.push_back(0xc0 | ((iUnicode & 0x07c0) >> 6));
				strString.push_back(0x80 | ((iUnicode & 0x003f) >> 0));
			}
			else
			{
				// character 0x0800 - 0xffff...

				strString.push_back(0xe0 | ((iUnicode & 0x00f000) >> 12));
				strString.push_back(0x80 | ((iUnicode & 0x000fc0) >>  6));
				strString.push_back(0x80 | ((iUnicode & 0x00003f) >>  0));
			}

			return strString;
		}
	};


	// ==========================================================================================================
	// ===                                   T H E   J S O N   G R A M M A R                                  ===
	// ==========================================================================================================

	template< typename Char >
	class grammar : public boost::spirit::grammar< grammar< Char > >
	{
	public:

		// ---[ TYPEDEFINITIONS ]---------------------------------------------------------------------------------

		typedef	boost::shared_ptr< boost::any >							variant;			//  pointer to a shared variant

		typedef	std::stack< variant >										stack;			//     a stack of json variants
		typedef	std::pair< std::basic_string< Char >, variant >		pair;				// a pair as it appears in json

		typedef	std::deque< variant >										array;			//    an array of json variants
		typedef	std::map< std::basic_string< Char >, variant >		object;			//    an object with json pairs

	protected:

		// ---[ SEMANTIC ACTION: PUSH A STRING ON THE STACK (AND ENCODE AS UTF-8) ]-------------------------------

		struct push_string
		{
			stack & m_stack;
			push_string(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator szStart, Iterator szEnd) const
			{
				// 1: skip the quotes...

				++szStart;
				--szEnd;

				// 2: traverse through the original string and check for escape codes..

				std::basic_string< typename Iterator::value_type > strString;

				while(szStart < szEnd)
				{
					// 2.1: if it's no escape code, just append to the resulting string...

					if (*szStart != static_cast< typename Iterator::value_type >('\\'))
					{
						// 2.1.1: append the character...

						strString.push_back(*szStart);
					}
					else
					{
						// 2.1.2: otherwise, check the escape code...

						++szStart;

						switch(*szStart)
						{
							default:
								
								strString.push_back(*szStart);
								break;
							
							case 'b':
								
								strString.push_back(static_cast< typename Iterator::value_type >('\b'));
								break;
							
							case 'f':
								
								strString.push_back(static_cast< typename Iterator::value_type >('\f'));
								break;
							
							case 'n':
								
								strString.push_back(static_cast< typename Iterator::value_type >('\n'));
								break;
							
							case 'r':
								
								strString.push_back(static_cast< typename Iterator::value_type >('\r'));
								break;

							case 't':
								
								strString.push_back(static_cast< typename Iterator::value_type >('\t'));
								break;

							case 'u':
							{
								// 2.1.2.1: convert the following hex value into an int...

								int iUnicode;
								std::basic_istringstream< Char >(std::basic_string< typename Iterator::value_type >(&szStart[1], 4)) >> std::hex >> iUnicode;

								szStart += 4;

								// 2.1.2.2: append the unicode int...

								strString.append(unicodecvt< typename Iterator::value_type >::convert(iUnicode));
							}
						}
					}

					// 2.2: go on with the next character...

					++szStart;
				}

				// 3: finally, push the string on the stack...

				m_stack.push(variant(new boost::any(strString)));
			}
		};


		// ---[ SEMANTIC ACTION: PUSH A REAL ON THE STACK ]-------------------------------------------------------

		struct push_double
		{
			stack & m_stack;
			push_double(stack & stack) : m_stack(stack) { }

			void operator() (double dValue) const
			{
				m_stack.push(variant(new boost::any(dValue)));
			}
		};


		// ---[ SEMANTIC ACTION: PUSH AN INT ON THE STACK ]-------------------------------------------------------

		struct push_int
		{
			stack & m_stack;
			push_int(stack & stack) : m_stack(stack) { }

			void operator() (long long iValue) const
			{
				m_stack.push(variant(new boost::any(iValue)));
			}
		};


		// ---[ SEMANTIC ACTION: PUSH A BOOLEAN ON THE STACK ]----------------------------------------------------

		struct push_boolean
		{
			stack & m_stack;
			push_boolean(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator szStart, Iterator /* szEnd */ ) const
			{
				// 1: push a boolean that is "true" if the string starts with 't' and "false" otherwise...

				m_stack.push(variant(new boost::any(*szStart == static_cast< typename Iterator::value_type >('t'))));
			}
		};


		// ---[ SEMANTIC ACTION: PUSH A NULL VALUE ON THE STACK ]-------------------------------------------------

		struct push_null
		{
			stack & m_stack;
			push_null(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator /* szStart */ , Iterator /* szEnd */ ) const
			{
				m_stack.push(variant(new boost::any()));
			}
		};


		// ---[ SEMANTIC ACTION: CREATE A "JSON PAIR" ON THE STACK ]----------------------------------------------

		struct create_pair
		{
			stack & m_stack;
			create_pair(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator /* szStart */, Iterator /* szEnd */ ) const
			{
				// 1: get the variant from the stack...

				variant var = m_stack.top();
				m_stack.pop();

				// 2: get the name from the stack...

				std::basic_string< typename Iterator::value_type > strName;

				try
				{
					strName = boost::any_cast< std::basic_string< typename Iterator::value_type > >(*m_stack.top());
				}
				catch(boost::bad_any_cast &) { /* NOTHING */ }

				m_stack.pop();

				// 3: push a pair of both on the stack...

				m_stack.push(variant(new boost::any(pair(strName, var))));
			}
		};


		// ---[ SEMANTIC ACTION: BEGIN AN ARRAY ]-----------------------------------------------------------------

		class	array_delimiter { /* EMPTY CLASS */ };

		struct begin_array
		{
			stack & m_stack;
			begin_array(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator /* cCharacter */) const
			{
				m_stack.push(variant(new boost::any(array_delimiter())));
			}
		};


		// ---[ SEMANTIC ACTION: CREATE AN ARRAY FROM THE VALUES ON THE STACK ]-----------------------------------

		struct end_array
		{
			stack & m_stack;
			end_array(stack & stack) : m_stack(stack) { }

			// - -[ functional operator ] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

			template <typename Iterator>
			void operator() (Iterator /* cCharacter */) const
			{
				// 1: create an array object and push everything in it, that's on the stack...

				variant varArray(new boost::any(array()));

				while(!m_stack.empty())
				{
					// 1.1: get the top most variant of the stack...

					variant var = m_stack.top();
					m_stack.pop();

					// 1.2: is it the end of the array? if yes => break the loop...

					if (boost::any_cast< array_delimiter >(var.get()) != NULL)
					{
						break;
					}

					// 1.3: otherwise, add to the array...

					boost::any_cast< array >(varArray.get())->push_front(var);
				}

				// 2: finally, push the array at the end of the stack...

				m_stack.push(varArray);
			}
		};


		// ---[ SEMANTIC ACTION: BEGIN AN OBJECT ]----------------------------------------------------------------

		class	object_delimiter { /* EMPTY CLASS */ };

		struct begin_object
		{
			stack & m_stack;
			begin_object(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator /* cCharacter */) const
			{
				m_stack.push(variant(new boost::any(object_delimiter())));
			}
		};


		// ---[ SEMANTIC ACTION: CREATE AN OBJECT FROM THE VALUES ON THE STACK ]----------------------------------

		struct end_object
		{
			stack & m_stack;
			end_object(stack & stack) : m_stack(stack) { }

			template <typename Iterator>
			void operator() (Iterator /* cCharacter */) const
			{
				// 1: create an array object and push everything in it, that's on the stack...

				variant varObject(new boost::any(object()));

				while(!m_stack.empty())
				{
					// 1.1: get the top most variant of the stack...

					variant var = m_stack.top();
					m_stack.pop();

					// 1.2: is it the end of the array? if yes => break the loop...
					
					if (boost::any_cast< object_delimiter >(var.get()) != NULL)
					{
						break;
					}

					// 1.3: if this is not a pair, we have a problem...

					pair * pPair = boost::any_cast< pair >(var.get());
					if (!pPair)
					{
						/* BIG PROBLEM!! */

						continue;
					}

					// 1.4: set the child of this object...

					boost::any_cast< object >(varObject.get())->insert(std::make_pair(pPair->first, pPair->second));
				}

				// 2: finally, push the array at the end of the stack...

				m_stack.push(varObject);
			}
		};

	public:

		stack & m_stack;
		grammar(stack & stack) : m_stack(stack) { }

		// ---[ THE ACTUAL GRAMMAR DEFINITION ]-------------------------------------------------------------------

		template <typename SCANNER>
		class definition
		{
			boost::spirit::rule< SCANNER > m_start;
			boost::spirit::rule< SCANNER > m_object;
			boost::spirit::rule< SCANNER > m_array;
			boost::spirit::rule< SCANNER > m_pair;
			boost::spirit::rule< SCANNER > m_value;
			boost::spirit::rule< SCANNER > m_string;
			boost::spirit::rule< SCANNER > m_number;
			boost::spirit::rule< SCANNER > m_boolean;
			boost::spirit::rule< SCANNER > m_null;

		public:

			boost::spirit::rule< SCANNER > const & start() const { return m_start; }

			// - -[ create the definition ] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

			definition(grammar const & self)
			{
				using namespace boost::spirit;

				// 0: JSON can either be an object or an array

				m_start
					= m_object
					| m_array;

				// 1: an object is an unordered set of pairs (seperated by commas)...

				m_object
					= ch_p('{') [ begin_object(self.m_stack) ] >>
					  !(m_pair >> *(ch_p(',') >> m_pair)) >>
					  ch_p('}') [ end_object  (self.m_stack) ];

				// 2: an array is an ordered collection of values (seperated by commas)...

				m_array
					= ch_p('[')	[ begin_array(self.m_stack) ] >>
					  !(m_value >> *(ch_p(',') >> m_value)) >>
					  ch_p(']')	[ end_array  (self.m_stack) ];

				// 3: a pair is given by a name and a value...

				m_pair
					= ( m_string >> ch_p(':') >> m_value )
					  [ create_pair(self.m_stack) ]
					;

				// 4: a value can be a string in double quotes, a number, a boolean, an object or an array.

				m_value
					= m_string
					| m_number
					| m_object
					| m_array
					| m_boolean
					| m_null
					;

				// 5: a string is a collection of zero or more unicode characters, wrapped in double quotes...

				m_string
					= lexeme_d
						[
							( ch_p('"') >> *(
								( (anychar_p - (ch_p('"') | ch_p('\\')))
								| ch_p('\\') >>
									( ch_p('\"')
									| ch_p('\\')
									| ch_p('/')
									| ch_p('b')
									| ch_p('f')
									| ch_p('n')
									| ch_p('r')
									| ch_p('t')
									| (ch_p('u') >> repeat_p(4)[ xdigit_p ])
									)
								)) >> ch_p('"') 
							)
							[ push_string(self.m_stack) ]
						]
					;

				// 6: a number is very much like a C or java number...

				m_number
					=   strict_real_p	[ push_double(self.m_stack) ]
					  | longlong_p		[ push_int	 (self.m_stack) ]
					;

				// 7: a boolean can be "true" or "false"...

				m_boolean
					= ( str_p("true")
					  | str_p("false")
					  )
					  [ push_boolean(self.m_stack) ]
					;

				// 8: finally, a value also can be a 'null', i.e. an empty item...

				m_null
					= str_p("null")
					  [ push_null(self.m_stack) ]
					;
			}
		};
	};


	// ==========================================================================================================
	// ===                          T H E   F I N A L   P A R S I N G   R O U T I N E                         ===
	// ==========================================================================================================

	template <typename Iterator>
	typename json::grammar< typename Iterator::value_type >::variant parse(Iterator const & szFirst, Iterator const & szEnd)
	{
		// 1: parse the input...

		json::grammar< typename Iterator::value_type >::stack st;
		json::grammar< typename Iterator::value_type > gr(st);

		boost::spirit::parse_info<Iterator> pi = boost::spirit::parse(szFirst, szEnd, gr, boost::spirit::space_p);

		// 2: skip any spaces at the end of the parsed section...

		while((pi.stop != szEnd) && (*pi.stop == static_cast< typename Iterator::value_type >(' ')))
		{
			++pi.stop;
		}

		// 3: if the input's end wasn't reached or if there is more than one object on the stack => cancel...

		if ((pi.stop != szEnd) || (st.size() != 1))
		{
			return json::grammar< typename Iterator::value_type >::variant(new boost::any());
		}

		// 4: otherwise, return the result...

		return st.top();
	}
};


#endif	// TINYJSON_HPP