`class Framer`

Encode and decode HTTY chunks on top of byte-oriented IO objects.

Definitions

`def initialize(input, output = input)`

Create a framer around the given input and output streams.

Signature

parameter　input　Interface(:read): The stream to read framed packets from.
parameter　output　Interface(:write, :flush) | Nil: The stream to write framed packets to.

Implementation

def initialize(input, output = input)
	@input = input
	@output = output
end

`def write_chunk(payload)`

Write a single HTTY chunk to the output stream.

Signature

parameter　payload　String | Array(Integer): The opaque bytes to encode.
returns　void

Implementation

def write_chunk(payload)
	encoded = Base64.strict_encode64(payload.to_s.b)
	@output.write("#{DCS}#{PREFIX}#{encoded}#{ST}")
end

`def read_chunk`

Read the next HTTY chunk from the input stream. Non-HTTY terminal output is ignored until a valid chunk prefix is found.

Signature

returns　String | Nil: The decoded payload, or nil on end of stream.
raises　ProtocolError: If the chunk prefix or chunk structure is invalid.
raises　ArgumentError: If the packet payload is not valid base64.
raises　EOFError: If the chunk terminator is missing.

Implementation

def read_chunk
	while payload = read_payload
		if payload.start_with?("HTTY;") && !payload.start_with?(PREFIX)
			raise ProtocolError, "Unsupported HTTY chunk version: #{payload.inspect}"
		end
		
		next unless payload.start_with?(PREFIX)
		encoded = payload.delete_prefix(PREFIX)
		return Base64.strict_decode64(encoded)
	end
	
	return nil
end

`def flush`

Flush the output stream if it supports flushing.

Signature

returns　void

Implementation

def flush
	@output.flush if @output.respond_to?(:flush)
end

`def close`

Close the wrapped input and output streams. If input and output are the same object, it is only closed once.

Signature

returns　void

Implementation

def close
	@output.close if @output.respond_to?(:close)
	@input.close if !@input.equal?(@output) && @input.respond_to?(:close)
end

`def closed?`

Check whether the output stream has been closed.

Signature

returns　bool: True if the output stream reports that it is closed.

Implementation

def closed?
	@output.respond_to?(:closed?) && @output.closed?
end