CFileInputStream.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include "io-precomp.h"  // Precompiled headers

#include <mrpt/core/exceptions.h>
#include <mrpt/io/CFileInputStream.h>

using namespace mrpt::io;
using namespace std;

static_assert(
    !std::is_copy_constructible_v<CFileInputStream> &&
        !std::is_copy_assignable_v<CFileInputStream>,
    "Copy Check");

CFileInputStream::CFileInputStream(const string& fileName) : m_if()
{
    MRPT_START

    // Try to open the file:
    // Open for input:
    if (!open(fileName))
        THROW_EXCEPTION_FMT(
            "Error trying to open file: '%s'", fileName.c_str());

    MRPT_END
}

/*---------------------------------------------------------------
                            Constructor
 ---------------------------------------------------------------*/
CFileInputStream::CFileInputStream() : m_if() {}
/*---------------------------------------------------------------
                            open
 ---------------------------------------------------------------*/
bool CFileInputStream::open(const string& fileName)
{
    // Try to open the file:
    // Open for input:
    m_if.open(fileName.c_str(), ios_base::binary | ios_base::in);
    return m_if.is_open();
}

/*---------------------------------------------------------------
                            close
 ---------------------------------------------------------------*/
void CFileInputStream::close()
{
    if (m_if.is_open()) m_if.close();
}

/*---------------------------------------------------------------
                            Destructor
 ---------------------------------------------------------------*/
CFileInputStream::~CFileInputStream() { close(); }
/*---------------------------------------------------------------
                            Read
            Reads bytes from the stream into Buffer
 ---------------------------------------------------------------*/
size_t CFileInputStream::Read(void* Buffer, size_t Count)
{
    if (!m_if.is_open()) return 0;

    m_if.read(static_cast<char*>(Buffer), Count);
    return m_if.fail() ? 0 : Count;
}

/*---------------------------------------------------------------
                            Write
            Writes a block of bytes to the stream.
 ---------------------------------------------------------------*/
size_t CFileInputStream::Write(
    [[maybe_unused]] const void* Buffer, [[maybe_unused]] size_t Count)
{
    THROW_EXCEPTION("Trying to write to a read file stream.");
}

/*---------------------------------------------------------------
                            Seek
    Method for moving to a specified position in the streamed resource.
     See documentation of CStream::Seek
 ---------------------------------------------------------------*/
uint64_t CFileInputStream::Seek(int64_t Offset, CStream::TSeekOrigin Origin)
{
    if (!m_if.is_open()) return 0;

    ifstream::off_type offset = Offset;
    ifstream::seekdir way;

    switch (Origin)
    {
        case sFromBeginning:
            way = ios_base::beg;
            break;
        case sFromCurrent:
            way = ios_base::cur;
            break;
        case sFromEnd:
            way = ios_base::end;
            break;
        default:
            THROW_EXCEPTION("Invalid value for 'Origin'");
    }

    m_if.seekg(offset, way);

    return getPosition();
}

/*---------------------------------------------------------------
                        getTotalBytesCount
 ---------------------------------------------------------------*/
uint64_t CFileInputStream::getTotalBytesCount() const
{
    if (!fileOpenCorrectly()) return 0;

    auto& f = const_cast<std::ifstream&>(m_if);

    const uint64_t previousPos = f.tellg();
    f.seekg(0, ios_base::end);
    uint64_t fileSize = f.tellg();
    f.seekg(previousPos, ios_base::beg);
    return fileSize;
}

/*---------------------------------------------------------------
                        getPosition
 ---------------------------------------------------------------*/
uint64_t CFileInputStream::getPosition() const
{
    auto& f = const_cast<std::ifstream&>(m_if);
    if (m_if.is_open())
        return f.tellg();
    else
        return 0;
}

/*---------------------------------------------------------------
                        fileOpenCorrectly
 ---------------------------------------------------------------*/
bool CFileInputStream::fileOpenCorrectly() const { return m_if.is_open(); }
/*---------------------------------------------------------------
                        readLine
 ---------------------------------------------------------------*/
bool CFileInputStream::readLine(string& str)
{
    str = string();  // clear() is not defined in VC6
    if (!m_if.is_open()) return false;

    std::getline(m_if, str);
    return !m_if.fail() && !m_if.eof();
}

/*---------------------------------------------------------------
                        checkEOF
 ---------------------------------------------------------------*/
bool CFileInputStream::checkEOF()
{
    if (!m_if.is_open()) return true;
    return m_if.eof();
}

void CFileInputStream::clearError()
{
    if (m_if.is_open()) m_if.clear();
}