FileInputStream.cpp

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#include <sys/types.h>
#include <sys/stat.h>

#include "FileInputStream.h"
#include "CS240Exception.h"




FileInputStream::FileInputStream(const std::string & url)
{
    fileSize = 0;
    numRead = 0;

    ParseURL(url);
    OpenFile();
}

FileInputStream::~FileInputStream()
{
    Close();
}

bool FileInputStream::IsOpen() const
{
    return file.is_open();
}

bool FileInputStream::IsDone() const
{
    return (numRead == fileSize);
}

char FileInputStream::Read()
{
    if (!IsOpen())
        throw IllegalStateException("stream is not open");
    else if (IsDone())
        throw IllegalStateException("stream is done");
    else
    {
        char c;
        file.get(c);

        if (file.fail())
            throw FileException(std::string("error reading from file ") + fileName);

        ++numRead;
        return c;
    }
}

char FileInputStream::Peek() 
{
    if (!IsOpen())
        throw IllegalStateException("stream is not open");
    else if (IsDone())
        throw IllegalStateException("stream is done");
    else
    {
        char c=file.peek();

        if (file.fail())
            throw FileException(std::string("error reading from file ") + fileName);

        return c;
    }
}

void FileInputStream::Close()
{
    if (IsOpen())
        file.close();
}

void FileInputStream::ParseURL(const std::string & url)
{
    const std::string prefix = "file:";
    fileName = url.substr(prefix.length());
}

void FileInputStream::OpenFile()
{
    struct stat buf;
    if (stat(fileName.c_str(), &buf) < 0)
        throw FileException(std::string("could not determine size of file ") + fileName);
    fileSize = buf.st_size;

    file.open(fileName.c_str());
    if (!IsOpen() || file.fail())
        throw FileException(std::string("could not open file ") + fileName);
}