`class File`

A body which reads from a file.

Definitions

`BLOCK_SIZE = 64*1024`

The default block size.

`MODE = ::File::RDONLY | ::File::BINARY`

The default mode for opening files.

`def self.open(path, *arguments, **options)`

Open a file at the given path.

Signature

parameter　path　String: the path to the file.

Implementation

def self.open(path, *arguments, **options)
	self.new(::File.open(path, MODE), *arguments, **options)
end

`def initialize(file, range = nil, size: file.size, block_size: BLOCK_SIZE)`

Initialize the file body with the given file.

Signature

parameter　file　::File: the file to read from.
parameter　range　Range: the range of bytes to read from the file.
parameter　size　Integer: the size of the file, if known.
parameter　block_size　Integer: the block size to use when reading from the file.

Implementation

def initialize(file, range = nil, size: file.size, block_size: BLOCK_SIZE)
	@file = file
	@range = range
	
	@block_size = block_size
	
	if range
		@file.seek(range.min)
		@offset = range.min
		@length = @remaining = range.size
	else
		@file.seek(0)
		@offset = 0
		@length = @remaining = size
	end
end

`def close(error = nil)`

Close the file.

Signature

parameter　error　Exception | Nil: the error that caused the file to be closed.

Implementation

def close(error = nil)
	@file.close
	@remaining = 0
	
	super
end

`attr :file`

Signature

attribute　::File: file the file to read from.

`attr :offset`

Signature

attribute　Integer: the offset to read from.

`attr :length`

Signature

attribute　Integer: the number of bytes to read.

`def empty?`

Signature

returns　Boolean: whether more data should be read.

Implementation

def empty?
	@remaining == 0
end

`def ready?`

Signature

returns　Boolean: whether the body is ready to be read, always true for files.

Implementation

def ready?
	true
end

`def buffered`

Returns a copy of the body, by duplicating the file descriptor, including the same range if specified.

Signature

returns　File: the duplicated body.

Implementation

def buffered
	self.class.new(@file.dup, @range, block_size: @block_size)
end

`def rewind`

Rewind the file to the beginning of the range.

Implementation

def rewind
	@file.seek(@offset)
	@remaining = @length
end

`def rewindable?`

Signature

returns　Boolean: whether the body is rewindable, generally always true for seekable files.

Implementation

def rewindable?
	true
end

`def read`

Read the next chunk of data from the file.

Signature

returns　String | Nil: the next chunk of data, or nil if the file is fully read.

Implementation

def read
	if @remaining > 0
		amount = [@remaining, @block_size].min
		
		if chunk = @file.read(amount)
			@remaining -= chunk.bytesize
			
			return chunk
		end
	end
end

`def join`

Read all the remaining data from the file and return it as a single string.

Signature

returns　String: the remaining data.

Implementation

def join
	return "" if @remaining == 0
	
	buffer = @file.read(@remaining)
	
	@remaining = 0
	
	return buffer
end

`def inspect`

Inspect the file body.

Signature

returns　String: a string representation of the file body.

Implementation

def inspect
	"\#<#{self.class} file=#{@file.inspect} offset=#{@offset} remaining=#{@remaining}>"
end