Qore::FileInputStream Class Reference

This class implements the InputStream interface for reading bytes from a file. More...

#include <QC_FileInputStream.dox.h>

Inheritance diagram for Qore::FileInputStream:

Public Member Methods
	constructor (string fileName, timeout timeout_ms=-1, *bool nonblocking_open)
	Creates the FileInputStream by opening a file. More...
int	peek ()
	Peeks the next byte available from the input stream; returns -1 if no more data available. More...
*binary	read (int limit)
	Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream. More...
Public Member Methods inherited from Qore::InputStream
	constructor ()
	Constructor. More...
abstract int	peek ()
	Peeks the next byte available from the input stream; returns -1 if no more data available. More...
abstract *binary	read (int limit)
	Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream. More...
Public Member Methods inherited from Qore::StreamBase
	constructor ()
	Throws an exception if called directly; this class can only be instantiated by builtin subclasses. More...
int	getThreadId ()
	Get the currently assigned thread id or -1 if not assigned to any thread.
nothing	reassignThread ()
	Reassigns current thread as thread used for stream manipulation. More...
nothing	unassignThread ()
	Unassigns current thread as thread used for stream manipulation. More...

Detailed Description

This class implements the InputStream interface for reading bytes from a file.

Restrictions:

Qore::PO_NO_FILESYSTEM

Example: FileInputStream basic usage

FileInputStream fis("file.ext");
binary *b;
while (b = fis.read(100)) {
    printf("read %s\n", make_hex_string(b));
}

Note

stream classes are not designed to be accessed from multiple threads; they have been implemented without locking for fast and efficient use when used from a single thread. For methods that would be unsafe to use in another thread, any use of such methods in threads other than the thread where the constructor was called will cause a STREAM-THREAD-ERROR to be thrown, unless the stream is handed off to another thread using the StreamBase::unassignThread() method in the thread that currently owns the stream, and the StreamBase::reassignThread() method in the new thread.

See also

StreamReader for a class that can be used to read various kinds of data from an InputStream

Since

Qore 0.8.13

Member Function Documentation

constructor()

Qore::FileInputStream::constructor	(	string	fileName,
		timeout	timeout_ms = -1,
		*bool	nonblocking_open
	)

Creates the FileInputStream by opening a file.

Parameters

fileName	the name of the file to open
timeout_ms	a timeout period with a resolution of milliseconds (a relative date/time value; integer arguments will be assumed to be milliseconds); if not given or negative the operations will never time out
nonblocking_open	if True, then the O_NONBLOCK flag will be set in the call to open() (2)

Exceptions

FILE-OPEN2-ERROR

if the file cannot be opened (does not exist, permission error, etc)

Since

Qore 0.9.3 added the nonblocking_open flag

peek()

int Qore::FileInputStream::peek ( )

virtual

Peeks the next byte available from the input stream; returns -1 if no more data available.

Returns

the next byte available from the input stream or -1 if no more data is available

Example:

FileInputStream fis("file.ext");
int nextByte = fis.peek();

Exceptions

FILE-READ-ERROR	if an I/O error occurs
FILE-READ-TIMEOUT-ERROR	if no byte could be read in the timeout specified in the constructor
STREAM-THREAD-ERROR	this exception is thrown if this method is called from any thread other than the thread that created the object

Implements Qore::InputStream.

read()

*binary Qore::FileInputStream::read ( int  limit )

virtual

Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream.

Parameters

limit

the maximum number of bytes to read

Returns

the read bytes (the length is between 1 and `limit` inclusive) or NOTHING if no more bytes are available

Example:

FileInputStream fis("file.ext");
*binary b;
while (b = fis.read(2)) {
    printf("read %s\n", make_hex_string(b));
}

Exceptions

FILE-READ-ERROR	if an I/O error occurs
FILE-READ-TIMEOUT-ERROR	if no byte could be read in the timeout specified in the constructor
INPUT-STREAM-ERROR	limit is not positive
STREAM-THREAD-ERROR	this exception is thrown if this method is called from any thread other than the thread that created the object

See also

FileInputStream::readString()

Implements Qore::InputStream.