data_impl.h

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/**************************************************************
 **
 ** @file data/data_impl.h
 **
 ** Copyright (C) 2012  Xpace, LLC.  All rights reserved
 **
 ** www.xpace.net
 **
 **************************************************************/

#ifndef XPACE_DATA_IMPL_H
#define XPACE_DATA_IMPL_H

#include <functional>

#include "base/types.h"
#include "data/data.h"

namespace Xpace
{
  // low-level returns
  enum NextDocResult
  {
    NDR_abort_false = -1,
    NDR_abort_true = -2
  };

  typedef std::function<int64(int64 val)> NextDocCallback;

  inline
  int64 defaultNextDoc
    (int64 doc)
  {
    return ++doc;
  }

  // Implements StatusCallback
  // combine (e.g.) a search result (nextDoc), a Sink result, and a status callback
  template <typename STORE> 
  class FindNextDoc
  {
  public:
    FindNextDoc
      (NextDocCallback nextDoc,
       typename STORE::Sink* sink,       
       StatusCallback status = defaultStatus) :
        next_doc(nextDoc),
        sink(sink),
        status(status),
        interval(1)
    {
    }

    int64 operator()
      (int64 doc_num)
    {
      // check search result first
      if ((doc_num = next_doc(doc_num)) < 0)
        // e.g. at end of refList
        return NDR_abort_true;

      // now check sink
      if (sink)
      {
        doc_num = sink->start(doc_num);
        if (doc_num < 0)
          // client abort 
          return NDR_abort_false;
      }

      // finally, check status
      if ((--interval == 0) &&
          ((interval = status(doc_num)) < 0))
        doc_num = NDR_abort_false;

      return doc_num;
    }

  private:
    StatusCallback next_doc;
    typename STORE::Sink* sink;
    StatusCallback status;
    uint64 interval;
  };
}

#endif