std.io.Read
Read
A type data can be read from (e.g. a File).
Required methods
read
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fn pub mut read(into: mut ByteArray, size: Int) -> Result[Int, Error]
fn pub mut read(into: mut ByteArray, size: Int) -> Result[Int, Error]
Reads up to size
bytes from self
into the given ByteArray
, returning
the number of bytes read.
The into
argument is the ByteArray
to read the bytes into. The capacity
of this ByteArray
is increased automatically if necessary.
The size
argument specifies how many bytes are to be read.
The return value is the number of bytes read.
The number of bytes read may be less than size
. This can happen for
different reasons, such as when all input is consumed or not enough data is
available (yet).
Default methods
read_all
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fn pub mut read_all(bytes: mut ByteArray) -> Result[Int, Error] {
let mut total = 0
let mut read_size = INITIAL_READ_ALL_SIZE
loop {
match read(into: bytes, size: read_size) {
case Ok(0) -> return Result.Ok(total)
case Ok(n) -> {
total += n
# To reduce the number of calls to `Reader.read` when there's lots of
# input to consume, we increase the read size if deemed beneficial.
if read_size < MAX_READ_ALL_SIZE and n == read_size { read_size *= 2 }
}
case Error(e) -> throw e
}
}
}
fn pub mut read_all(bytes: mut ByteArray) -> Result[Int, Error]
Reads from self
into the given ByteArray
, returning when all input is
consumed.
The return value is the number of bytes read.
Errors
This method returns an Error
if the underlying call to Read.read
returns
an Error
.
read_exact
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fn pub mut read_exact(into: mut ByteArray, size: Int) -> Result[Nil, Error] {
let mut pending = size
while pending > 0 {
match read(into, pending) {
case Ok(0) if pending > 0 -> throw Error.EndOfInput
case Ok(n) -> pending -= n
case Error(e) -> throw e
}
}
Result.Ok(nil)
}
fn pub mut read_exact(into: mut ByteArray, size: Int) -> Result[Nil, Error]
Reads exactly size
bytes into into
.
Whereas Read.read
might return early if fewer bytes are available in the
input stream, Read.read_exact
continues reading until the desired amount
of bytes is read.
Errors
If the end of the input stream is encountered before filling the buffer, an
Error.EndOfInput
error is returned.
If an error is returned, no assumption can be made about the state of the
into
buffer, i.e. there's no guarantee data read so far is in the buffer
in the event of an error.
Implementations
ReadOnlyFile
impl Read for ReadOnlyFile
ReadWriteFile
impl Read for ReadWriteFile
Buffer
impl Read for Buffer
BufferedReader
impl Read for BufferedReader
Socket
impl Read for Socket
TcpClient
impl Read for TcpClient
UdpSocket
impl Read for UdpSocket
UnixClient
impl Read for UnixClient
UnixDatagram
impl Read for UnixDatagram
UnixSocket
impl Read for UnixSocket
Client
impl Read for Client
Server
impl Read for Server
Stdin
impl Read for Stdin
Stderr
impl Read for Stderr
Stdout
impl Read for Stdout