CompoundDataReader.hpp

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/* 
 * CompoundDataReader.hpp 
 *
 * This file is part of the Chemical Data Processing Toolkit
 *
 * Copyright (C) 2003 Thomas Seidel <thomas.seidel@univie.ac.at>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; see the file COPYING. If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */
 
#ifndef CDPL_UTIL_COMPOUNDDATAREADER_HPP
#define CDPL_UTIL_COMPOUNDDATAREADER_HPP
 
#include <vector>
#include <algorithm>
#include <functional>
 
#include "CDPL/Base/DataReader.hpp"
#include "CDPL/Base/Exceptions.hpp"
 
 
namespace CDPL
{
 
    namespace Util
    {
 
        template <typename DataType>
        class CompoundDataReader : public Base::DataReader<DataType>
        {
 
          public:
            typedef std::shared_ptr<CompoundDataReader> SharedPointer;
 
            typedef Base::DataReader<DataType>         ReaderType;
            typedef typename ReaderType::SharedPointer ReaderPointer;
 
            CompoundDataReader();
 
            ~CompoundDataReader();
 
            CompoundDataReader(const CompoundDataReader&) = delete;
 
            CompoundDataReader& operator=(const CompoundDataReader&) = delete;
 
            void addReader(const ReaderPointer& reader);
 
            void removeReader(std::size_t idx);
 
            std::size_t getNumReaders();
 
            void clear();
 
            std::size_t getReaderIDForRecordIndex(std::size_t idx) const;
 
            const ReaderPointer& getReader(std::size_t idx) const;
 
            CompoundDataReader& read(DataType& obj, bool overwrite = true);
            CompoundDataReader& read(std::size_t idx, DataType& obj, bool overwrite = true);
 
            CompoundDataReader& skip();
 
            bool hasMoreData();
 
            std::size_t getRecordIndex() const;
            void setRecordIndex(std::size_t idx);
 
            std::size_t getNumRecords();
 
            operator const void*() const;
            bool operator!() const;
 
          private:
            ReaderType* getReaderForRecordIndex(std::size_t& idx) const;
 
            typedef std::vector<ReaderPointer> ReaderArray;
            typedef std::vector<std::size_t>   RecordIndexArray;
 
            ReaderArray      readers;
            bool             state;
            RecordIndexArray recordIdxBounds;
            std::size_t      recordIdx;
            std::size_t      numRecords;
        };
    } // namespace Util
} // namespace CDPL
 
 
// Implementation
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>::CompoundDataReader():
    state(false), recordIdx(0), numRecords(0)
{}
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>::~CompoundDataReader()
{
    clear();
}
 
template <typename DataType>
void CDPL::Util::CompoundDataReader<DataType>::clear()
{
    std::for_each(readers.begin(), readers.end(),
                  std::bind(&ReaderType::setParent, std::placeholders::_1,
                            static_cast<CompoundDataReader*>(0)));
    readers.clear();
    recordIdxBounds.clear();
 
    numRecords = 0;
    state      = false;
    recordIdx  = 0;
}
 
template <typename DataType>
void CDPL::Util::CompoundDataReader<DataType>::addReader(const ReaderPointer& reader)
{
    readers.reserve(readers.size() + 1);
    recordIdxBounds.reserve(readers.size() + 1);
 
    reader->setParent(this);
 
    std::size_t num_recs = reader->getNumRecords();
 
    readers.push_back(reader);
    numRecords += num_recs;
    recordIdxBounds.push_back(numRecords);
 
    state |= static_cast<bool>(reader->operator const void*());
}
 
template <typename DataType>
void CDPL::Util::CompoundDataReader<DataType>::removeReader(std::size_t idx)
{
    if (idx >= readers.size())
        throw Base::IndexError("CompoundDataReader: reader index out of bounds");
 
    std::size_t num_lost_records = readers[idx]->getNumRecords();
 
    readers[idx]->setParent(0);
 
    readers.erase(readers.begin() + idx);
    recordIdxBounds.erase(recordIdxBounds.begin() + idx);
 
    for (; idx < readers.size(); idx++)
        recordIdxBounds[idx] -= num_lost_records;
 
    numRecords -= num_lost_records;
}
 
template <typename DataType>
std::size_t CDPL::Util::CompoundDataReader<DataType>::getNumReaders()
{
    return readers.size();
}
 
template <typename DataType>
const typename CDPL::Util::CompoundDataReader<DataType>::ReaderPointer&
CDPL::Util::CompoundDataReader<DataType>::getReader(std::size_t idx) const
{
    if (idx >= readers.size())
        throw Base::IndexError("CompoundDataReader: reader index out of bounds");
 
    return readers[idx];
}
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>&
CDPL::Util::CompoundDataReader<DataType>::read(DataType& obj, bool overwrite)
{
    state = false;
 
    std::size_t idx    = recordIdx;
    ReaderType* reader = getReaderForRecordIndex(idx);
 
    if (reader && (state = reader->read(idx, obj, overwrite))) {
        recordIdx++;
        this->invokeIOCallbacks(1.0);
    }
 
    return *this;
}
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>&
CDPL::Util::CompoundDataReader<DataType>::read(std::size_t idx, DataType& obj, bool overwrite)
{
    setRecordIndex(idx);
 
    return read(obj, overwrite);
}
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>&
CDPL::Util::CompoundDataReader<DataType>::skip()
{
    state = false;
 
    if (recordIdx >= numRecords)
        return *this;
 
    recordIdx++;
    state = true;
 
    this->invokeIOCallbacks(1.0);
 
    return *this;
}
 
template <typename DataType>
bool CDPL::Util::CompoundDataReader<DataType>::hasMoreData()
{
    return (recordIdx < numRecords);
}
 
template <typename DataType>
std::size_t CDPL::Util::CompoundDataReader<DataType>::getRecordIndex() const
{
    return recordIdx;
}
 
template <typename DataType>
void CDPL::Util::CompoundDataReader<DataType>::setRecordIndex(std::size_t idx)
{
    if (idx >= numRecords)
        throw Base::IndexError("CompoundDataReader: record index out of bounds");
 
    recordIdx = idx;
}
 
template <typename DataType>
std::size_t CDPL::Util::CompoundDataReader<DataType>::getNumRecords()
{
    return numRecords;
}
 
template <typename DataType>
CDPL::Util::CompoundDataReader<DataType>::operator const void*() const
{
    return (state ? this : 0);
}
 
template <typename DataType>
bool CDPL::Util::CompoundDataReader<DataType>::operator!() const
{
    return !state;
}
 
template <typename DataType>
std::size_t CDPL::Util::CompoundDataReader<DataType>::getReaderIDForRecordIndex(std::size_t idx) const
{
    for (std::size_t i = 0; i < readers.size(); i++) {
        if (idx < recordIdxBounds[i])
            return (i + 1);
    }
 
    return 0;
}
 
template <typename DataType>
typename CDPL::Util::CompoundDataReader<DataType>::ReaderType*
CDPL::Util::CompoundDataReader<DataType>::getReaderForRecordIndex(std::size_t& idx) const
{
    for (std::size_t i = 0; i < readers.size(); i++) {
        if (idx < recordIdxBounds[i]) {
            idx -= (i == 0 ? std::size_t(0) : recordIdxBounds[i - 1]);
            return readers[i].get();
        }
    }
 
    return 0;
}
 
#endif // CDPL_UTIL_COMPOUNDDATAREADER_HPP