lemur::api::DocStream Class Reference

Abstract interface for a collection of documents. More...

#include <DocStream.hpp>

Inheritance diagram for lemur::api::DocStream:

List of all members.

Public Member Functions
virtual	~DocStream ()
virtual void	startDocIteration ()=0
	start document iteration
virtual bool	hasMore ()=0
virtual Document *	nextDoc ()=0
	return a pointer to next document (static memory, do not delete returned instance). hasMore() should be called before calling nextDoc()

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Detailed Description

Abstract interface for a collection of documents.

DocStream is an abstract interface for a collection of documents. A given realization can have special tokenization, document header formats, etc, and will return a special Document instance to indicate this.

The following is an example of supporting an index with position information:

An example of supporting index with position information

      // a DocStream that handles position
      class PosDocStream : public DocStream {
      ... 
      Document *nextDoc() {
      return (new PosDocument(...)); // returns a special Document
      } 
      ...
      };

      // a Document that has position information 
      class PosDocument : public Document {
      ... 
      TokenTerm  *nextTerm() {
      return (new PosTerm(...)); // returns a special Term
      }
      };

      // a Term that has position 
      class PosTerm: public TokenTerm {
      int getPosition() { 
      ...
      }
      };

      // Indexer that records term positions
      class PosIndex : public Index {
      ...
      PosDocStream *db;

      ... // when indexing

      db->startDocIteration();
      Document *doc;
      while (db->hasMore()) {
      Document *doc = db->nextDoc(); // we'll actually get a PosDocument
      doc->startTermIteration();
      PosTerm *term;
      while (doc->hasMore()) {
      term = (PosTerm *)nextTerm(term); 
      // note that down-casting!
      term->getPosition();
      term->spelling();
      ...

      }
      }
      ... 
      }
      

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Constructor & Destructor Documentation

virtual lemur::api::DocStream::~DocStream (   )  [inline, virtual]

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Member Function Documentation

virtual bool lemur::api::DocStream::hasMore (   )  [pure virtual]

Implemented in lemur::parse::BasicDocStream.

virtual Document* lemur::api::DocStream::nextDoc (   )  [pure virtual]

return a pointer to next document (static memory, do not delete returned instance). hasMore() should be called before calling nextDoc() Implemented in lemur::parse::BasicDocStream.

virtual void lemur::api::DocStream::startDocIteration (   )  [pure virtual]

start document iteration Implemented in lemur::parse::BasicDocStream.

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The documentation for this class was generated from the following file:

• DocStream.hpp

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