FileReaderT.h

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/*
 * Copyright (C) 2007-2010 RobotCub Consortium, European Commission FP6 Project IST-004370
 * author:  Arjan Gijsberts
 * email:   arjan.gijsberts@iit.it
 * website: www.robotcub.org
 * Permission is granted to copy, distribute, and/or modify this program
 * under the terms of the GNU General Public License, version 2 or any
 * later version published by the Free Software Foundation.
 *
 * A copy of the license can be found at
 * http://www.robotcub.org/icub/license/gpl.txt
 *
 * This program 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 General
 * Public License for more details
 */
 
#ifndef ICUB_FILEREADERT__
#define ICUB_FILEREADERT__
 
#include <string>
#include <fstream>
#include <stdexcept>
 
namespace iCub {
namespace learningmachine {
 
 
template<class T>
class FileReaderT {
private:
    std::istream* stream;
 
    std::ifstream* f_stream;
 
    void clearStream() {
        // close file stream if present
        if(this->f_stream != (std::ifstream*) 0) {
            this->f_stream->close();
        }
        // do not need to clear normal stream, as we already clear f_stream and
        // don't want to delete std::cin
        delete this->f_stream;
        this->f_stream = (std::ifstream*) 0;
    }
 
    void checkStream() {
        if(this->stream == (std::istream*) 0) {
            throw std::runtime_error("no stream opened.");
        }
    }
 
public:
    FileReaderT() {
        stream = (std::istream*) 0;
        f_stream = (std::ifstream*) 0;
    }
 
    ~FileReaderT() {
        this->clearStream();
    }
 
    virtual void open(std::istream& s) {
        // destroy previous stream if applicable
        this->stream = &s;
    }
 
    virtual void open(const std::string& f) {
        // clear previous filestream
        this->clearStream();
        // put stream on the heap!
        this->f_stream = new std::ifstream(f.c_str());
        if(!this->f_stream->is_open()) {
            this->clearStream();
            throw std::runtime_error(std::string("could not open file '" + f + "'"));
        }
        return this->open(*this->f_stream);
    }
 
    virtual bool hasNext() {
        this->checkStream();
        // peek so that eof bit is set
        this->stream->peek();
        return !this->stream->eof();
    }
 
    virtual void reset() {
        this->stream->clear();
        this->stream->seekg(0, std::ios::beg);
    }
 
    T* getNext() {
        // check if there are actually more items
        if(!hasNext()) {
            throw std::runtime_error("end of stream.");
        }
 
        // read next line
        std::string line;
        getline(*this->stream, line);
 
        // construct and fill object
        T* obj = new T();
        obj->fromString(line.c_str());
 
        return obj;
    }
};
 
} // learningmachine
} // iCub
 
#endif