/home/palakars/workspace-inprogress/code-in-progress/aitools3/aitools3-aq-invertedindex-cpp/src/reader/InvertedFileReader.hpp

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/* Copyright (C) 2010 webis.de
 * All rights reserved.
 */
#ifndef AITOOLS_INVERTEDINDEX_INVERTED_FILE_READER_HPP
#define AITOOLS_INVERTEDINDEX_INVERTED_FILE_READER_HPP

#include "RecordReader.hpp"
#include <boost/filesystem/fstream.hpp>

namespace bfs = boost::filesystem;

namespace aitools {
namespace invertedindex {

template<typename Value>
class InvertedFileReader : public RecordReader<Value> {

public: // c'tor / d'tor

        InvertedFileReader();

        InvertedFileReader(const bfs::path& path) throw (std::invalid_argument);

        ~InvertedFileReader();

public: // methods

        void close();

        bool is_open() const;

        const bfs::path& path() const;

        bool next(Record<Value>& record);

        void open(const bfs::path& path) throw (std::invalid_argument);

private: // data

        bfs::ifstream ifs_;
        std::string   key_;
        bfs::path     path_;

};

// IMPLEMENTATION

template<typename Value>
InvertedFileReader<Value>::InvertedFileReader()
{}

template<typename Value>
InvertedFileReader<Value>::InvertedFileReader(const bfs::path& path)
throw (std::invalid_argument)
{
        open(path);
}

template<typename Value>
InvertedFileReader<Value>::~InvertedFileReader()
{}

template<typename Value>
void
InvertedFileReader<Value>::close()
{
        ifs_.close();
        key_.clear();
        path_ = bfs::path();
}

template<typename Value>
bool
InvertedFileReader<Value>::is_open() const
{
        return ifs_.is_open();
}

template<typename Value>
const bfs::path&
InvertedFileReader<Value>::path() const
{
        return path_;
}

template<typename Value>
bool
InvertedFileReader<Value>::next(Record<Value>& record)
{
        while (ifs_.good())
        {
                switch (ifs_.peek())
                {
                case ' ':
                case '\t':
                        ifs_.get();
                        break;
                case '\r':
                case '\n':
                        ifs_ >> key_;
                        break;
                default:
                        record.key().assign(key_);
                        ifs_ >> record.value();
                        return true;
                }
        }
        return false;
}

template<typename Value>
void
InvertedFileReader<Value>::open(const bfs::path& path)
throw (std::invalid_argument)
{
        ifs_.open(path);
        if (!ifs_)
        {
                Exception::throw_invalid_argument("Cannot open", path);
        }
        ifs_ >> key_; // Read first key
}

} // namespace invertedindex
} // namespace aitools

#endif // AITOOLS_INVERTEDINDEX_INVERTED_FILE_READER_HPP

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