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ExtentRestrictionModelAnnotatorCopier.hpp

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/*==========================================================================
 * Copyright (c) 2004 University of Massachusetts.  All Rights Reserved.
 *
 * Use of the Lemur Toolkit for Language Modeling and Information Retrieval
 * is subject to the terms of the software license set forth in the LICENSE
 * file included with this software, and also available at
 * http://www.lemurproject.org/license.html
 *
 *==========================================================================
*/


//
// ExtentRestrictionModelAnnotatorCopier
//
// 16 August 2004 -- tds
//
// This copier annotates RawScorerNodes with the language models
// of the surrounding ExtentRestrictions.
//
// For example, the query #combine[sentence]( dog cat )
// should be synonymous with #combine[sentence]( dog.(sentence) cat.(sentence) ).
// We push the sentence language model down the tree and attach it to "dog" and "cat".
//

#ifndef INDRI_EXTENTRESTRICTIONMODELANNOTATORCOPIER_HPP
#define INDRI_EXTENTRESTRICTIONMODELANNOTATORCOPIER_HPP

#include <stack>
#include <vector>
#include "indri/QuerySpec.hpp"

class ExtentRestrictionModelAnnotatorCopier : public indri::lang::Copier {
private:
  std::vector<indri::lang::Node*> _nodes;
  std::stack< indri::lang::ExtentRestriction* > _restrictions;

public:
  ~ExtentRestrictionModelAnnotatorCopier() {
    delete_vector_contents( _nodes );
  }

  indri::lang::Node* defaultAfter( indri::lang::Node* old, indri::lang::Node* newNode ) {
    _nodes.push_back( newNode );
    return newNode;
  }

  void before( indri::lang::ExtentRestriction* old ) {
    _restrictions.push( old );
  }

  indri::lang::Node* after( indri::lang::ExtentRestriction* oldNode, indri::lang::ExtentRestriction* newNode ) {
    _restrictions.pop();
    _nodes.push_back( newNode );
    return newNode;
  }
  
  indri::lang::Node* after( indri::lang::RawScorerNode* oldNode, indri::lang::RawScorerNode* newNode ) {
    if( newNode->getContext() == 0 && _restrictions.size() ) {
      newNode->setContext( _restrictions.top()->getField() );
    }

    return newNode;
  }
};

#endif // INDRI_EXTENTRESTRICTIONMODELANNOTATORCOPIER_HPP

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