gStore/Parser/TurtleParser.h

#ifndef H_tools_rdf3xload_TurtleParser
#define H_tools_rdf3xload_TurtleParser
//---------------------------------------------------------------------------
// RDF-3X
// (c) 2008 Thomas Neumann. Web site: http://www.mpi-inf.mpg.de/~neumann/rdf3x
//
// This work is licensed under the Creative Commons
// Attribution-Noncommercial-Share Alike 3.0 Unported License. To view a copy
// of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/
// or send a letter to Creative Commons, 171 Second Street, Suite 300,
// San Francisco, California, 94105, USA.
//---------------------------------------------------------------------------
#include "Type.h"
#include "../Util/Util.h"
//---------------------------------------------------------------------------
/// Parse a turtle file
class TurtleParser
{
   public:
   /// A parse error
   class Exception {
      public:
      /// The message
      std::string message;

      /// Constructor
      Exception(const std::string& message);
      /// Constructor
      Exception(const char* message);
      /// Destructor
      ~Exception();
   };

   private:
   /// A turtle lexer
   class Lexer {
      public:
      /// Possible tokens
      enum Token { Token_Eof, Token_Dot, Token_Colon, Token_Comma, Token_Semicolon, Token_LBracket, Token_RBracket, Token_LParen, Token_RParen, Token_At, Token_Type, Token_Integer, Token_Decimal, Token_Double, Token_Name, Token_A, Token_True, Token_False, Token_String, Token_URI };

      private:
      /// The input
      std::istream& in;
      /// The putback
      Token putBack;
      /// The putback string
      std::string putBackValue;
      /// Buffer for parsing when ignoring the value
      std::string ignored;
      /// The current line
      unsigned line;

      /// Size of the read buffer
      static const unsigned readBufferSize = 1024;
      /// Read buffer
      char readBuffer[readBufferSize];
      /// Read buffer pointers
      char* readBufferStart,*readBufferEnd;

      /// Read new characters
      bool doRead(char& c);
      /// Read a character
      bool read(char& c) { if (readBufferStart<readBufferEnd) { c=*(readBufferStart++); return true; } else return doRead(c); }
      /// Unread the last character
      void unread() { readBufferStart--; }

      /// Lex a hex code
      unsigned lexHexCode(unsigned len);
      /// Lex an escape sequence
      void lexEscape(std::string& token);
      /// Lex a long string
      Token lexLongString(std::string& token);
      /// Lex a string
      Token lexString(std::string& token,char c);
      /// Lex a URI
      Token lexURI(std::string& token,char c);
      /// Lex a number
      Token lexNumber(std::string& token,char c);

      public:
      /// Constructor
      Lexer(std::istream& in);
      /// Destructor
      ~Lexer();

      /// The next token (including value)
      Token next(std::string& value);
      /// The next token (ignoring the value)
      Token next() { return next(ignored); }
      /// Put a token and a string back
      void unget(Token t,const std::string& s) { putBack=t; if (t>=Token_Integer) putBackValue=s; }
      /// Put a token back
      void ungetIgnored(Token t) { putBack=t; if (t>=Token_Integer) putBackValue=ignored; }
      /// Get the line
      unsigned getLine() const { return line; }

	  void discardLine()
	  {
		  char c;
		  while (read(c) && c != '\n');
	  }
   };
   /// A triple
   struct Triple {
      /// The entries
      std::string subject,predicate,object,objectSubType;
      /// Type for the object
      Type::Type_ID objectType;

      /// Constructor
      Triple(const std::string& subject,const std::string& predicate,const std::string& object,Type::Type_ID objectType,const std::string& objectSubType) : subject(subject),predicate(predicate),object(object),objectSubType(objectSubType),objectType(objectType) {}
   };

   /// The lexer
   Lexer lexer;
   /// The uri base
   std::string base;
   /// All known prefixes
   std::map<std::string,std::string> prefixes;
   /// The currently available triples
   std::vector<Triple> triples;
   /// Reader in the triples
   unsigned triplesReader;
   /// The next blank node id
   unsigned nextBlank;

   /// Is a (generalized) name token?
   static inline bool isName(Lexer::Token token);

   // Convert a relative URI into an absolute one
   void constructAbsoluteURI(std::string& uri);
   /// Construct a new blank node
   void newBlankNode(std::string& node);
   /// Report an error
   void parseError(const std::string& message);
   /// Parse a qualified name
   void parseQualifiedName(const std::string& prefix,std::string& name);
   /// Parse a blank entry
   void parseBlank(std::string& entry);
   /// Parse a subject
   void parseSubject(Lexer::Token token,std::string& subject);
   /// Parse an object
   void parseObject(std::string& object,Type::Type_ID& objectType,std::string& objectSubType);
   /// Parse a predicate object list
   void parsePredicateObjectList(const std::string& subject,std::string& predicate,std::string& object,Type::Type_ID& objectType,std::string& objectSubType);
   /// Parse a directive
   void parseDirective();
   /// Parse a new triple
   void parseTriple(Lexer::Token token,std::string& subject,std::string& predicate,std::string& object,Type::Type_ID& objectType,std::string& objectSubType);

   public:
   /// Constructor
   TurtleParser(std::istream& in);
   /// Destructor
   ~TurtleParser();

   /// Read the next triple
   bool parse(std::string& subject,std::string& predicate,std::string& object,Type::Type_ID& objectType,std::string& objectSubType);

   void discardLine()
   {
	   lexer.discardLine();
   }
};
//---------------------------------------------------------------------------
#endif