Creates an empty, resizeable and writeable IO::Memory with the given initial capacity for the internal buffer.

io = IO::Memory.new
slice = Bytes.new(1)
io.pos         # => 0
io.read(slice) # => 0
slice          # => Bytes[0]

Creates an IO::Memory whose contents are the exact contents of string. The created IO::Memory is non-resizeable and non-writeable.

The IO starts at position zero for reading.

io = IO::Memory.new "hello"
io.pos        # => 0
io.gets(2)    # => "he"
io.print "hi" # raises IO::Error

Creates an IO::Memory that will read, and optionally write, from/to the given slice. The created IO::Memory is non-resizeable.

The IO starts at position zero for reading.

slice = Slice.new(6) { |i| ('a'.ord + i).to_u8 }
io = IO::Memory.new slice, writeable: false
io.pos            # => 0
io.read(slice)    # => 6
String.new(slice) # => "abcdef"

Returns the internal buffer as a Pointer(UInt8).

Same as #size.

Clears the internal buffer and resets the position to zero. Raises if this IO::Memory is non-resizeable.

io = IO::Memory.new
io << "abc"
io.rewind
io.gets(1) # => "a"
io.clear
io.pos         # => 0
io.gets_to_end # => ""

io = IO::Memory.new "hello"
io.clear # raises IO::Error

Closes this IO. Further operations on this IO will raise an IO::Error.

io = IO::Memory.new "hello"
io.close
io.gets_to_end # raises IO::Error (closed stream)

Determines if this IO is closed.

io = IO::Memory.new "hello"
io.closed? # => false
io.close
io.closed? # => true

Returns true if this IO::Memory has no contents.

io = IO::Memory.new
io.empty? # => true
io.print "hello"
io.empty? # => false

Returns the current position (in bytes) of this IO.

io = IO::Memory.new "hello"
io.pos     # => 0
io.gets(2) # => "he"
io.pos     # => 2

Sets the current position (in bytes) of this IO.

io = IO::Memory.new "hello"
io.pos = 3
io.gets # => "lo"

See IO#read(slice).

Yields an IO::Memory to read a section of this IO's buffer.

During the block duration self becomes read-only, so multiple concurrent open are allowed.

Rewinds this IO to the initial position (zero).

io = IO::Memory.new "hello"
io.gets(2) # => "he"
io.rewind
io.gets(2) # => "he"

Seeks to a given offset (in bytes) according to the whence argument.

io = IO::Memory.new("abcdef")
io.gets(3) # => "abc"
io.seek(1, IO::Seek::Set)
io.gets(2) # => "bc"
io.seek(-1, IO::Seek::Current)
io.gets(1) # => "c"

Returns the total number of bytes in this IO.

io = IO::Memory.new "hello"
io.size # => 5

Appends this internal buffer to the given IO.

Returns a new String that contains the contents of the internal buffer.

io = IO::Memory.new
io.print 1, 2, 3
io.to_s # => "123"

Returns the underlying bytes.

io = IO::Memory.new
io.print "hello"

io.to_slice # => Bytes[104, 101, 108, 108, 111]

See IO#write(slice). Raises if this IO::Memory is non-writeable, or if it's non-resizeable and a resize is needed.

See IO#write_byte. Raises if this IO::Memory is non-writeable, or if it's non-resizeable and a resize is needed.