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class IO::Memory
inherits IO

An IO that reads and writes from a buffer in memory.

The internal buffer can be resizeable and/or writeable depending on how an IO::Memory is constructed.

Class methods

.new(capacity : Int = 64)

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]
View source

.new(string : String)

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
View source

.new(slice : Bytes, writeable = true)

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"
View source

Methods

#buffer : Pointer(UInt8)

Returns the internal buffer as a Pointer(UInt8).

View source

#bytesize : Int32

Same as size.

View source

#clear

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
View source

#close

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)
View source

#closed? : Bool

Determines if this IO is closed.

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

#empty?

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

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

#pos : Int32

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

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

#pos=(value)

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

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

#read(slice : Bytes)

See IO#read(slice).

View source

#read_at(offset, bytesize, & : IO -> )

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.

View source

#rewind

Rewinds this IO to the initial position (zero).

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

#seek(offset, whence : Seek = Seek::Set)

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"
View source

#size : Int32

Returns the total number of bytes in this IO.

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

#to_s(io : IO) : Nil

Appends this internal buffer to the given IO.

View source

#to_s : String

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"
View source

#to_slice : Bytes

Returns the underlying bytes.

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

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

#write(slice : Bytes) : Nil

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

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#write_byte(byte : UInt8)

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

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