mailiverse/cpp/Lib/cajun-2.0.2/json/reader.inl

/******************************************************************************

Copyright (c) 2009-2010, Terry Caton
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#include <cassert>
#include <set>
#include <sstream>

/*  

TODO:
* better documentation
* unicode character decoding

*/

namespace json
{

template<typename istream>
inline istream& operator >> (istream& istr, UnknownElement& elementRoot) {
   Reader<istream>::Read(elementRoot, istr);
   return istr;
}

//////////////////////
// Reader::InputStream
///////////////////
// Reader (finally)


template <typename istream>
template <typename ElementTypeT>   
void Reader<istream>::Read_i(ElementTypeT& element, istream& istr)
{
   Reader reader;

   Tokens tokens;
   InputStream inputStream(istr);
   reader.Scan(tokens, inputStream);

   TokenStream tokenStream(tokens);
   reader.Parse(element, tokenStream);

   if (tokenStream.EOS() == false)
   {
      const Token& token = tokenStream.Peek();
      std::string sMessage = std::string("Expected End of token stream; found ") + token.sValue;
      throw ParseException(sMessage, token.locBegin, token.locEnd);
   }
}

template <typename istream>
inline void Reader<istream>::Scan(Tokens& tokens, InputStream& inputStream)
{
   while (EatWhiteSpace(inputStream),              // ignore any leading white space...
          inputStream.EOS() == false) // ...before checking for EOS
   {
      // if all goes well, we'll create a token each pass
      Token token;
      token.locBegin = inputStream.GetLocation();

      // gives us null-terminated string
      char sChar = inputStream.Peek();
      switch (sChar)
      {
         case '{':
            token.sValue = MatchExpectedString(inputStream, "{");
            token.nType = Token::TOKEN_OBJECT_BEGIN;
            break;

         case '}':
            token.sValue = MatchExpectedString(inputStream, "}");
            token.nType = Token::TOKEN_OBJECT_END;
            break;

         case '[':
            token.sValue = MatchExpectedString(inputStream, "[");
            token.nType = Token::TOKEN_ARRAY_BEGIN;
            break;

         case ']':
            token.sValue = MatchExpectedString(inputStream, "]");
            token.nType = Token::TOKEN_ARRAY_END;
            break;

         case ',':
            token.sValue = MatchExpectedString(inputStream, ",");
            token.nType = Token::TOKEN_NEXT_ELEMENT;
            break;

         case ':':
            token.sValue = MatchExpectedString(inputStream, ":");
            token.nType = Token::TOKEN_MEMBER_ASSIGN;
            break;

         case '"':
            token.sValue = MatchString(inputStream);
            token.nType = Token::TOKEN_STRING;
            break;

         case '-':
         case '0':
         case '1':
         case '2':
         case '3':
         case '4':
         case '5':
         case '6':
         case '7':
         case '8':
         case '9':
            token.nValue = MatchNumber(inputStream);
            token.nType = Token::TOKEN_NUMBER;
            break;

         case 't':
            token.sValue = MatchExpectedString(inputStream, "true");
            token.nType = Token::TOKEN_BOOLEAN;
            break;

         case 'f':
            token.sValue = MatchExpectedString(inputStream, "false");
            token.nType = Token::TOKEN_BOOLEAN;
            break;

         case 'n':
            token.sValue = MatchExpectedString(inputStream, "null");
            token.nType = Token::TOKEN_NULL;
            break;

         default:
         {
            std::string sErrorMessage = std::string("Unexpected character in stream: ") + sChar;
            throw ScanException(sErrorMessage, inputStream.GetLocation());
         }
      }

      token.locEnd = inputStream.GetLocation();
      tokens.push_back(token);
   }
}


template <typename istream>
inline void Reader<istream>::EatWhiteSpace(InputStream& inputStream)
{
   while (inputStream.EOS() == false && 
          ::isspace(inputStream.Peek()))
      inputStream.Get();
}

template <typename istream>
inline const std::string &Reader<istream>::MatchExpectedString(InputStream& inputStream, const std::string& sExpected)
{
   std::string::const_iterator it(sExpected.begin()),
                               itEnd(sExpected.end());
   for ( ; it != itEnd; ++it) {
      if (inputStream.EOS() ||      // did we reach the end before finding what we're looking for...
          inputStream.Get() != *it) // ...or did we find something different?
      {
         std::string sMessage = std::string("Expected string: ") + sExpected;
         throw ScanException(sMessage, inputStream.GetLocation());
      }
   }

   // all's well if we made it here
   return sExpected;
}

inline unsigned int decodeUnicodeCodePoint (InputStream& inputStream)
{
	unsigned int v_[2];
	unsigned int &unicode = v_[0];
	unsigned int &surrogate = v_[1];

	for (int n=0; n<2; n++)
	{
		unsigned int &v = v_[x];
		v = 0;
		
		for (int i=3; i>=0 && !inputStream.EOS(); --i)
		{
			char c = inputStream.Get();
			unsigned int ord = 0;
			if ('0' <= c && c <= '9')
				ord = c - '0';
			else
			if ('A' <= c && c <= 'F')
				ord = 10 + (c - 'A');
			else
			if ('a' <= c && c <= 'f')
				ord = 10 + (c - 'a');
				
			v |= ord << (4 * i);
		}
		
		bool hasSurrogate = false;
		if (v >= 0xD800 && v <= 0xDBFF)
		{
			int pos = inputStream.TellG();
			
			if (!inputStream.Get() != '\\' || !inputStream.Get() != 'u')
				inputStream.SetG(pos);
			else
				hasSurrogate = true;
		}
		
		if (!hasSurrogate)
			break;
	}

	if (n == 2)
		unicode = 0x10000 + ((unicode & 0x3FF) << 10) + (surrogate & 0x3FF);
		
	return unicode;
}

inline std::string codePointToUTF8(unsigned int cp)
{
   std::string result;
   
   // based on description from http://en.wikipedia.org/wiki/UTF-8

   if (cp <= 0x7f) 
   {
      result.resize(1);
      result[0] = static_cast<char>(cp);
   } 
   else if (cp <= 0x7FF) 
   {
      result.resize(2);
      result[1] = static_cast<char>(0x80 | (0x3f & cp));
      result[0] = static_cast<char>(0xC0 | (0x1f & (cp >> 6)));
   } 
   else if (cp <= 0xFFFF) 
   {
      result.resize(3);
      result[2] = static_cast<char>(0x80 | (0x3f & cp));
      result[1] = 0x80 | static_cast<char>((0x3f & (cp >> 6)));
      result[0] = 0xE0 | static_cast<char>((0xf & (cp >> 12)));
   }
   else if (cp <= 0x10FFFF) 
   {
      result.resize(4);
      result[3] = static_cast<char>(0x80 | (0x3f & cp));
      result[2] = static_cast<char>(0x80 | (0x3f & (cp >> 6)));
      result[1] = static_cast<char>(0x80 | (0x3f & (cp >> 12)));
      result[0] = static_cast<char>(0xF0 | (0x7 & (cp >> 18)));
   }

   return result;
}

template <typename istream>
inline const std::string &Reader<istream>::MatchString(InputStream& inputStream)
{
   MatchExpectedString(inputStream, "\"");

   buffer.resize(0);
   std::string &string = buffer;
   
   while (inputStream.EOS() == false &&
          inputStream.Peek() != '"')
   {
      char c = inputStream.Get();

      // escape?
      if (c == '\\' &&
          inputStream.EOS() == false) // shouldn't have reached the end yet
      {
         c = inputStream.Get();
         switch (c) {
            case '/':      string.push_back('/');     break;
            case '"':      string.push_back('"');     break;
            case '\\':     string.push_back('\\');    break;
            case 'b':      string.push_back('\b');    break;
            case 'f':      string.push_back('\f');    break;
            case 'n':      string.push_back('\n');    break;
            case 'r':      string.push_back('\r');    break;
            case 't':      string.push_back('\t');    break;
            case 'u': 
			{
				string += codePointToUTF8(decodeUnicodeCodePoint(inputStream));
			}
			break;
            default: {
               std::string sMessage = std::string("Unrecognized escape sequence found in string: \\") + c;
               throw ScanException(sMessage, inputStream.GetLocation());
            }
         }
      }
      else {
         string.push_back(c);
      }
   }

   // eat the last '"' that we just peeked
   MatchExpectedString(inputStream, "\"");

   // all's well if we made it here
   return buffer;
}


template <typename istream>
inline Number::ValueType Reader<istream>::MatchNumber(InputStream& inputStream)
{
	const int MAX_BUF=255;
	char buffer[MAX_BUF+1];
	char p = 0;
	
   while (p<MAX_BUF && inputStream.EOS() == false &&
          numericChars.find(inputStream.Peek()) != numericChars.end())
   {
	buffer[p++] = inputStream.Get();
   }
   buffer[p] = 0;
   
#ifdef JSON_USE_STRING_AS_NUMBER
	return json::NumberString(buffer);
#else
   int base=0;
   char *end;
   return strtol(buffer,&end, base);
#endif
}

template <typename istream>
inline void Reader<istream>::Parse(UnknownElement& element, Reader::TokenStream& tokenStream) 
{
   const Token& token = tokenStream.Peek();
   switch (token.nType) {
      case Token::TOKEN_OBJECT_BEGIN:
      {
         // implicit non-const cast will perform conversion for us (if necessary)
         Object& object = element;
         Parse(object, tokenStream);
         break;
      }

      case Token::TOKEN_ARRAY_BEGIN:
      {
         Array& array = element;
         Parse(array, tokenStream);
         break;
      }

      case Token::TOKEN_STRING:
      {
         String& string = element;
         Parse(string, tokenStream);
         break;
      }

      case Token::TOKEN_NUMBER:
      {
         Number& number = element;
         Parse(number, tokenStream);
         break;
      }

      case Token::TOKEN_BOOLEAN:
      {
         Boolean& boolean = element;
         Parse(boolean, tokenStream);
         break;
      }

      case Token::TOKEN_NULL:
      {
         Null& null = element;
         Parse(null, tokenStream);
         break;
      }

      default:
      {
         std::string sMessage = std::string("Unexpected token: ") + token.sValue;
         throw ParseException(sMessage, token.locBegin, token.locEnd);
      }
   }
}


template <typename istream>
inline void Reader<istream>::Parse(Object& object, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_OBJECT_BEGIN, tokenStream);

   bool bContinue = (tokenStream.EOS() == false &&
                     tokenStream.Peek().nType != Token::TOKEN_OBJECT_END);
   while (bContinue)
   {
      Object::Member member;

      // first the member name. save the token in case we have to throw an exception
      const Token& tokenName = tokenStream.Peek();
      member.name = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);

      // ...then the key/value separator...
      MatchExpectedToken(Token::TOKEN_MEMBER_ASSIGN, tokenStream);

      // ...then the value itself (can be anything).
      Parse(member.element, tokenStream);

      // try adding it to the object (this could throw)
      try
      {
         object.Insert(member);
      }
      catch (Exception&)
      {
         // must be a duplicate name
         std::string sMessage = std::string("Duplicate object member token: ") + member.name; 
         throw ParseException(sMessage, tokenName.locBegin, tokenName.locEnd);
      }

      bContinue = (tokenStream.EOS() == false &&
                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
      if (bContinue)
         MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
   }

   MatchExpectedToken(Token::TOKEN_OBJECT_END, tokenStream);
}

template <typename istream>
inline void Reader<istream>::Parse(Array& array, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_ARRAY_BEGIN, tokenStream);

   bool bContinue = (tokenStream.EOS() == false &&
                     tokenStream.Peek().nType != Token::TOKEN_ARRAY_END);
   while (bContinue)
   {
      // ...what's next? could be anything
      Array::iterator itElement = array.Insert(UnknownElement());
      UnknownElement& element = *itElement;
      Parse(element, tokenStream);

      bContinue = (tokenStream.EOS() == false &&
                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
      if (bContinue)
         MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
   }

   MatchExpectedToken(Token::TOKEN_ARRAY_END, tokenStream);
}

template <typename istream>
inline void Reader<istream>::Parse(String& string, Reader::TokenStream& tokenStream)
{
   string = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
}


template <typename istream>
inline void Reader<istream>::Parse(Number& number, Reader::TokenStream& tokenStream)
{
/*
#ifdef JSON_USE_STRING_AS_NUMBER
   const std::string& sValue = MatchExpectedToken(Token::TOKEN_NUMBER, tokenStream);
	
//   std::istringstream iStr(sValue);
   Number::ValueType dValue;
//   iStr >> dValue;

	int base=0;
	char *end;
	const char *s = sValue.c_str();
	dValue = strtol(s, &end, base);

   // did we consume all characters in the token?
   if (*end != '\0')
//   if (iStr.eof() == false)
   {
 //     char c = iStr.peek();
	char c = *end;
      std::string sMessage = std::string("Unexpected character in NUMBER token: ") + c;
      throw ParseException(sMessage, currentToken.locBegin, currentToken.locEnd);
   }

   number = dValue;
#else
*/
   const Token& currentToken = tokenStream.Get(); // might need this later for throwing exception
	number = currentToken.nValue;
//#endif
}


template <typename istream>
inline void Reader<istream>::Parse(Boolean& boolean, Reader::TokenStream& tokenStream)
{
   const std::string& sValue = MatchExpectedToken(Token::TOKEN_BOOLEAN, tokenStream);
   boolean = (sValue == "true" ? true : false);
}


template <typename istream>
inline void Reader<istream>::Parse(Null&, Reader::TokenStream& tokenStream)
{
   MatchExpectedToken(Token::TOKEN_NULL, tokenStream);
}


} // End namespace