Module: IO::Like

### Home Classes Methods

### In Files

- lib/io/like.rb

### Methods

- #<<
- #binmode
- #close
- #close_read
- #close_write
- #closed?
- #duplexed?
- #each
- #each_byte
- #each_line
- #eof
- #eof?
- #fcntl
- #fileno
- #fill_size
- #fill_size=
- #flush
- #flush_size
- #flush_size=
- #getc
- #gets
- #isatty
- #lineno
- #lineno=
- #path
- #pos
- #pos=
- #print
- #printf
- #putc
- #puts
- #read
- #read_ready?
- #readable?
- #readbytes
- #readchar
- #readline
- #readlines
- #readpartial
- #rewind
- #seek
- #seekable?
- #sync
- #sync=
- #sysread
- #sysseek
- #syswrite
- #tell
- #to_io
- #tty?
- #ungetc
- #unread
- #writable?
- #write
- #write_ready?

### Included Modules

- Enumerable

### Files

- CONTRIBUTORS
- GPL
- HACKING
- LEGAL
- LICENSE
- NEWS

### Class/Module Index

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- IO
- IO::Like

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# IO::Like

IO::Like is a module which provides most of the basic input and output functions of IO objects using methods named unbuffered_read, unbuffered_write, and unbuffered_seek.

## Readers

In order to use this module to provide input methods, a class which includes it must provide the unbuffered_read method which takes one argument, a length, as follows:

    def unbuffered_read(length)
      ...
    end

This method must return at most length bytes as a String, raise EOFError if reading begins at the end of data, and raise SystemCallError on error. Errno::EAGAIN should be raised if there is no data to return immediately and the read operation should not block. Errno::EINTR should be raised if the read operation is interrupted before any data is read.

## Writers

In order to use this module to provide output methods, a class which includes it must provide the unbuffered_write method which takes a single string argument as follows:

    def unbuffered_write(string)
      ...
    end

This method must either return the number of bytes written to the stream, which may be less than the length of string in bytes, OR must raise an instance of SystemCallError. Errno::EAGAIN should be raised if no data can be written immediately and the write operation should not block. Errno::EINTR should be raised if the write operation is interrupted before any data is written.

## Seekers

In order to use this module to provide seeking methods, a class which includes it must provide the unbuffered_seek method which takes two required arguments, an offset and a start position, as follows:

    def unbuffered_seek(offset, whence)
      ...
    end

This method must return the new position within the data stream relative to the beginning of the stream and should raise SystemCallError on error. offset can be any integer and whence can be any of IO::SEEK_SET, IO::SEEK_CUR, or IO::SEEK_END. They are interpreted together as follows:

          whence | resulting position
    -------------+------------------------------------------------------------
    IO::SEEK_SET | Add offset to the position of the beginning of the stream.
    -------------+------------------------------------------------------------
    IO::SEEK_CUR | Add offset to the current position of the stream.
    -------------+------------------------------------------------------------
    IO::SEEK_END | Add offset to the position of the end of the stream.

## Duplexed Streams

In order to create a duplexed stream where writing and reading happen independently of each other, override the duplexed? method to return `true` and then provide the unbuffered_read and unbuffered_write methods. Do NOT provide an unbuffered_seek method or the contents of the internal read and write buffers may be lost unexpectedly.

NOTE: Due to limitations of Ruby's finalizer, IO::Like#close is not automatically called when the object is garbage collected, so it must be explicitly called when the object is no longer needed or risk losing whatever data remains in the internal write buffer.

### Public Instance Methods

ios << obj → ios click to toggle source

Writes obj to the stream using write and returns ios. obj is converted to a String using to_s.

    # File lib/io/like.rb, line 82
    def <<(obj)
      write(obj)
      self
    end

binmode → ios click to toggle source

Returns `self`. Just for compatibility with IO.

    # File lib/io/like.rb, line 91
    def binmode
      self
    end

close → nil click to toggle source

Arranges for closed? to return `true`. Raises IOError if closed? already returns `true`. For duplexed objects, calls close_read and close_write. For non-duplexed objects, calls flush if writable? returns `true` and then sets a flag so that closed? will return `true`.

    # File lib/io/like.rb, line 102
    def close
      raise IOError, 'closed stream' if closed?
      __io_like__close_read
      flush if writable?
      __io_like__close_write
      nil
    end

close_read → nil click to toggle source

Closes the read end of a duplexed object or the whole object if the object is read-only.

Raises IOError if closed? returns `true`. Raises IOError for duplexed objects if called more than once. Raises IOError for non-duplexed objects if writable? returns `true`.

    # File lib/io/like.rb, line 119
    def close_read
      raise IOError, 'closed stream' if closed?
      if __io_like__closed_read? || ! duplexed? && writable? then
        raise IOError, 'closing non-duplex IO for reading'
      end
      if duplexed? then
        __io_like__close_read
      else
        close
      end
      nil
    end

close_write → nil click to toggle source

Closes the write end of a duplexed object or the whole object if the object is write-only.

Raises IOError if closed? returns `true`. Raises IOError for duplexed objects if called more than once. Raises IOError for non-duplexed objects if readable? returns `true`.

    # File lib/io/like.rb, line 141
    def close_write
      raise IOError, 'closed stream' if closed?
      if __io_like__closed_write? || ! duplexed? && readable? then
        raise IOError, 'closing non-duplex IO for reading'
      end
      if duplexed? then
        flush
        __io_like__close_write
      else
        close
      end
      nil
    end

closed? → true or false click to toggle source

Returns `true` if this object is closed or otherwise unusable for read and write operations.

    # File lib/io/like.rb, line 160
    def closed?
      (__io_like__closed_read? || ! readable?) &&
      (__io_like__closed_write? || ! writable?)
    end

duplexed? → true or false click to toggle source

Returns `false`. Override this to return `true` when creating duplexed IO objects.

    # File lib/io/like.rb, line 170
    def duplexed?
      false
    end

each(sep_string = $/) click to toggle source
Alias for: each_line
each_byte { |byte| block } → ios click to toggle source

Reads each byte (0..255) from the stream using getc and calls the given block once for each byte, passing the byte as an argument.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception and the conversion of EOFError results into `nil` results, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 185
    def each_byte
      while (byte = getc) do
        yield(byte)
      end
      self
    end

each_line(sep_string = $/) { |line| block } → ios click to toggle source
each(sep_string = $/) { |line| block } → ios

Reads each line from the stream using gets and calls the given block once for each line, passing the line as an argument.

NOTE: When sep_string is not `nil`, this method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception and the conversion of EOFError results into `nil` results, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 204
    def each_line(sep_string = $/)
      while (line = gets(sep_string)) do
        yield(line)
      end
      self
    end

Also aliased as: each
eof() click to toggle source
Alias for: eof?
eof? → true or false click to toggle source
eof → true or false

Returns `true` if there is no more data to read.

This works by using getc to fetch the next character and using ungetc to put the character back if one was fetched. It may be a good idea to replace this implementation in derivative classes.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception and the conversion of EOFError results into `nil` results, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 227
    def eof?
      if (char = getc) then
        ungetc(char)
        return false
      end
      true
    end

Also aliased as: eof
fcntl click to toggle source

Raises NotImplementedError.

    # File lib/io/like.rb, line 240
    def fcntl(*args)
      raise NotImplementedError, 'not implemented'
    end

fileno → nil click to toggle source

Returns `nil`. Just for compatibility with IO.

    # File lib/io/like.rb, line 248
    def fileno
      nil
    end

fill_size → integer click to toggle source

Returns the number of bytes to read as a block whenever the internal buffer needs to be refilled. Unless set explicitly via fill_size=, this defaults to 4096.

Raises IOError if closed? returns `true`. Raises IOError if the stream is not opened for reading.

    # File lib/io/like.rb, line 261
    def fill_size
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?

      @__io_like__fill_size ||= 4096
    end

fill_size = integer → integer click to toggle source

Sets the number of bytes to read as a block whenever the internal read buffer needs to be refilled. The new value must be a number greater than or equal to 0. Setting this to 0 effectively disables buffering.

Raises IOError if closed? returns `true`. Raises IOError if the stream is not opened for reading.

    # File lib/io/like.rb, line 277
    def fill_size=(fill_size)
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?

      unless fill_size >= 0 then
        raise ArgumentError, "non-positive fill_size #{fill_size} given"
      end
      @__io_like__fill_size = fill_size
    end

flush → ios click to toggle source

Flushes the internal write buffer to the underlying data stream.

Regardless of the blocking status of the data stream or interruptions during writing, this method will block until either all the data is flushed or until an error is raised.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to flush the internal write buffer. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

    # File lib/io/like.rb, line 304
    def flush
      begin
        __io_like__buffered_flush
      rescue Errno::EAGAIN, Errno::EINTR
        retry if write_ready?
      end
      self
    end

flush_size → integer click to toggle source

Returns the number of bytes at which the internal write buffer is flushed automatically to the data stream. Unless set explicitly via flush_size=, this defaults to 4096.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

    # File lib/io/like.rb, line 322
    def flush_size
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for writing' unless writable?

      @__io_like__flush_size ||= 4096
    end

flush_size = integer → integer click to toggle source

Sets the number of bytes at which the internal write buffer is flushed automatically to the data stream. The new value must be a number greater than or equal to 0. Setting this to 0 effectively disables buffering.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

    # File lib/io/like.rb, line 338
    def flush_size=(flush_size)
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for writing' unless writable?

      unless flush_size >= 0 then
        raise ArgumentError, "non-positive flush_size #{flush_size} given"
      end
      @__io_like__flush_size = flush_size
    end

getc → nil or integer click to toggle source

Calls readchar and either returns the result or `nil` if readchar raises EOFError.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`. Raises all errors raised by unbuffered_read except for EOFError.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception and the conversion of EOFError results into `nil` results, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 363
    def getc
      readchar
    rescue EOFError
      nil
    end

gets(sep_string = $/) → nil or string click to toggle source

Calls readline with sep_string as an argument and either returns the result or `nil` if readline raises EOFError. If readline returns some data, `$.` is set to the value of lineno.

NOTE: Due to limitations of MRI up to version 1.9.x when running managed (Ruby) code, this method fails to set `$_` to the returned data; however, other implementations may allow it.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`. Raises all errors raised by unbuffered_read except for EOFError.

NOTE: When sep_string is not `nil`, this method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method will always block in that case. Aside from that exception, this method will raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 389
    def gets(sep_string = $/)
      # Set the last read line in the global.
      $_ = readline(sep_string)
      # Set the last line number in the global.
      $. = lineno
      # Return the last read line.
      $_
    rescue EOFError
      nil
    end

isatty → false click to toggle source

Returns `false`. Just for compatibility with IO.

Raises IOError if closed? returns `true`.

    # File lib/io/like.rb, line 406
    def isatty
      raise IOError, 'closed stream' if closed?
      false
    end

Also aliased as: tty?
lineno → integer click to toggle source

Returns the number of times gets was called and returned non-`nil` data. By default this is the number of lines read, but calling gets or any of the other line-based reading methods with a non-default value for sep_string or after changing `$/` will affect this.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

    # File lib/io/like.rb, line 422
    def lineno
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?
      @__io_like__lineno ||= 0
    end

lineno = lineno → lineno click to toggle source

Sets the current line number to the given value. `$.` is updated by the next call to gets. If the object given is not an integer, it is converted to one using its to_int method.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

    # File lib/io/like.rb, line 437
    def lineno=(integer)
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?
      if integer.nil? then
        raise TypeError, 'no implicit conversion from nil to integer'
      elsif ! integer.respond_to?(:to_int) then
        raise TypeError, "can't convert #{integer.class} into Integer"
      end
      @__io_like__lineno = integer.to_int
    end

path → nil click to toggle source

Returns `nil`. Just for compatibility with IO.

    # File lib/io/like.rb, line 452
    def path
      nil
    end

pos → integer click to toggle source

Returns the current offest of ios.

Raises IOError if closed? returns `true`. Raises Errno::ESPIPE unless seekable? returns `true`.

As a side effect, the internal write buffer is flushed unless this is a writable, non-duplexed object. This is for compatibility with the behavior of IO#pos.

NOTE: Because this method relies on unbuffered_seek and unbuffered_write (when the internal write buffer is not empty), it will also raise the same errors and block at the same times as those functions.

    # File lib/io/like.rb, line 489
    def pos
      # Flush the internal write buffer for writable, non-duplexed objects.
      __io_like__buffered_flush if writable? && ! duplexed?
      __io_like__buffered_seek(0, IO::SEEK_CUR)
    end

Also aliased as: tell
pos = position → position click to toggle source

Sets the data position to position by calling seek.

As a side effect, the internal read and write buffers are flushed.

Raises IOError if closed? returns `true`. Raises Errno::ESPIPE unless seekable? returns `true`.

NOTE: Because this method relies on unbuffered_seek and unbuffered_write (when the internal write buffer is not empty), it will also raise the same errors and block at the same times as those functions.

    # File lib/io/like.rb, line 469
    def pos=(position)
      seek(position, IO::SEEK_SET)
      position
    end

print([obj, ...]) → nil click to toggle source

Writes the given object(s), if any, to the stream using write after converting them to strings by calling their to_s methods. If no objects are given, `$_` is used. The field separator (`$,`) is written between successive objects if it is not `nil`. The output record separator (<tt>$</tt>) is written after all other data if it is not nil.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to immediately write +[obj, ...]+ completely. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

    # File lib/io/like.rb, line 514
    def print(*args)
      args << $_ if args.empty?
      first_arg = true
      args.each do |arg|
        # Write a field separator before writing each argument after the first
        # one unless no field separator is specified.
        if first_arg then
          first_arg = false
        elsif ! $,.nil? then
          write($,)
        end

        # If the argument is nil, write 'nil'; otherwise, write the stringified
        # form of the argument.
        if arg.nil? then
          write('nil')
        else
          write(arg)
        end
      end

      # Write the output record separator if one is specified.
      write($\) unless $\.nil?
      nil
    end

printf(format_string [, obj, ...]) → nil click to toggle source

Writes the String returned by calling Kernel.sprintf using the given arguments.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to immediately write its arguments completely. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

    # File lib/io/like.rb, line 554
    def printf(*args)
      write(sprintf(*args))
      nil
    end

putc(obj) → obj click to toggle source

If obj is a String, write the first byte; otherwise, convert obj to a integer using its to_int method and write the low order byte.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to immediately write obj completely. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

    # File lib/io/like.rb, line 573
    def putc(obj)
      char = case obj
             when String
               obj[0].chr
             else
               [obj.to_int].pack('V')[0].chr
             end
      write(char)
      obj
    end

puts([obj, ...]) → nil click to toggle source

Writes the given object(s), if any, to the stream using write after converting them to strings using their to_s methods. Unlike print, Array instances are recursively processed. A record separator character is written after each object which does not end with the record separator already. If no objects are given, a single record separator is written.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to immediately write +[obj, ...]+ completely. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

NOTE: In order to be compatible with IO#puts, the record separator is currently hardcoded to be a single newline (`"\n"`) even though the documentation implies that the output record separator (<tt>$</tt>) should be used.

    # File lib/io/like.rb, line 606
    def puts(*args)
      # Set the output record separator such that this method is compatible with
      # IO#puts.
      ors = "\n"

      # Write only the record separator if no arguments are given.
      if args.length == 0 then
        write(ors)
        return
      end

      # Write each argument followed by the record separator.  Recursively
      # process arguments which are Array instances.
      args.each do |arg|
        line = arg.nil? ?
                 'nil' :
                 arg.kind_of?(Array) ?
                   __io_like__array_join(arg, ors) :
                   arg.to_s
        line += ors if line.index(ors, -ors.length).nil?
        write(line)
      end

      nil
    end

read([length[, buffer]]) → nil, buffer, or string click to toggle source

If length is specified and is a positive integer, at most length bytes are returned. Truncated data will occur if there is insufficient data left to fulfill the request. If the read starts at the end of data, `nil` is returned.

If length is unspecified or `nil`, an attempt to return all remaining data is made. Partial data will be returned if a low-level error is raised after some data is retrieved. If no data would be returned at all, an empty String is returned.

If buffer is specified, it will be converted to a String using its `to_str` method if necessary and will be filled with the returned data if any.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

NOTE: Because this method relies on unbuffered_read, it will also raise the same errors and block at the same times as that function.

    # File lib/io/like.rb, line 654
    def read(length = nil, buffer = nil)
      # Check the validity of the method arguments.
      unless length.nil? || length >= 0 then
        raise ArgumentError, "negative length #{length} given"
      end
      buffer = buffer.nil? ? '' : buffer.to_str
      buffer.slice!(0..-1) unless buffer.empty?

      if length.nil? then
        # Read and return everything.
        begin
          loop do
            buffer << __io_like__buffered_read(4096)
          end
        rescue EOFError
          # Ignore this.
        rescue SystemCallError
          # Reraise the error if there is nothing to return.
          raise if buffer.empty?
        end
      else
        # Read and return up to length bytes.
        begin
          buffer << __io_like__buffered_read(length)
        rescue EOFError
          # Return nil to the caller at end of file when requesting a specific
          # amount of data.
          return nil
        end
      end
      buffer
    end

read_ready? → true or false click to toggle source

Returns `true` when the stream may be read without error, `false` otherwise. This method will block until one of the conditions is known.

This default implementation of read_ready? is a hack which should be able to work for both real IO objects and IO-like objects; however, it is inefficient since it merely sleeps for 1 second and then returns `true` as long as closed? returns `false`. IO.select should be used for real IO objects to wait for a readable condition on platforms with support for IO.select. Other solutions should be found as necessary to improve this implementation on a case by case basis.

Basically, this method should be overridden in derivative classes.

    # File lib/io/like.rb, line 702
    def read_ready?
      return false unless readable?
      sleep(1)
      true
    end

readable? → true or false click to toggle source

Returns `true` if the stream is both open and readable, `false` otherwise.

This implementation checks to see if unbuffered_read is defined in order to make its determination. Override this if the implementing class always provides the unbuffered_read method but may not always be open in a readable mode.

    # File lib/io/like.rb, line 717
    def readable?
      ! __io_like__closed_read? && respond_to?(:unbuffered_read, true)
    end

readbytes(length) → string click to toggle source

Reads and returns length bytes from the data stream.

Raises EOFError if reading begins at the end of the stream. Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`. Raises TruncatedDataError if insufficient data is immediately available to satisfy the request.

In the case of TruncatedDataError being raised, the retrieved data can be fetched from the data attribute of the exception.

This method is basically copied from IO#readbytes.

NOTE: Because this method relies on unbuffered_read, it will also raise the same errors and block at the same times as that function.

    # File lib/io/like.rb, line 738
    def readbytes(length)
      buffer = read(length)
      if buffer.nil? then
        raise EOFError, "end of file reached"
      end
      if buffer.length < length then
        raise TruncatedDataError.new("data truncated", buffer)
      end
      buffer
    end

readchar → integer click to toggle source

Returns the next 8-bit byte (0..255) from the stream.

Raises EOFError when there is no more data in the stream. Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 762
    def readchar
      __io_like__buffered_read(1)[0]
    rescue Errno::EAGAIN, Errno::EINTR
      retry if read_ready?
    end

readline(sep_string = $/) → string click to toggle source

Returns the next line from the stream, where lines are separated by sep_string. Increments lineno by `1` for each call regardless of the value of sep_string.

If sep_string is not `nil` and not a String, it is first converted to a String using its `to_str` method and processing continues as follows.

If sep_string is `nil`, a line is defined as the remaining contents of the stream. Partial data will be returned if a low-level error of any kind is raised after some data is retrieved. This is equivalent to calling read without any arguments except that this method will raise an EOFError if called at the end of the stream.

If sep_string is an empty String, a paragraph is returned, where a paragraph is defined as data followed by 2 or more successive newline characters. A maximum of 2 newlines are returned at the end of the returned data. Fewer may be returned if the stream ends before at least 2 successive newlines are seen.

Any other value for sep_string is used as a delimiter to mark the end of a line. The returned data includes this delimiter unless the stream ends before the delimiter is seen.

In any case, the end of the stream terminates the current line.

Raises EOFError when there is no more data in the stream. Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

NOTE: When sep_string is not `nil`, this method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method will always block in that case. Aside from that exception, this method will raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 805
    def readline(sep_string = $/)
      # Ensure that sep_string is either nil or a String.
      unless sep_string.nil? || sep_string.kind_of?(String) then
        sep_string = sep_string.to_str
      end

      buffer = ''
      begin
        if sep_string.nil? then
          # A nil line separator means that the user wants to capture all the
          # remaining input.
          loop do
            buffer << __io_like__buffered_read(4096)
          end
        else
          begin
            # Record if the user requested paragraphs rather than lines.
            paragraph_requested = sep_string.empty?
            # An empty line separator string indicates that the user wants to
            # return paragraphs.  A pair of newlines in the stream is used to
            # mark this.
            sep_string = "\n\n" if paragraph_requested

            # Add each character from the input to the buffer until either the
            # buffer has the right ending or the end of the input is reached.
            while buffer.index(sep_string, -sep_string.length).nil? &&
                  (char = __io_like__buffered_read(1)) do
              buffer << char
            end

            if paragraph_requested then
              # If the user requested paragraphs instead of lines, we need to
              # consume and discard all newlines remaining at the front of the
              # input.
              while char == "\n" && (char = __io_like__buffered_read(1)) do
                nil
              end
              # Put back the last character.
              ungetc(char[0])
            end
          rescue Errno::EAGAIN, Errno::EINTR
            retry if read_ready?
          end
        end
      rescue EOFError, SystemCallError
        # Reraise the error if there is nothing to return.
        raise if buffer.empty?
      end
      # Increment the number of times this method has returned a "line".
      self.lineno += 1
      buffer
    end

readlines(sep_string = $/) → array click to toggle source

Returns an Array containing the lines in the stream using each_line.

If sep_string is `nil`, a line is defined as the remaining contents of the stream. If sep_string is not a String, it is converted to one using its `to_str` method. If sep_string is empty, a paragraph is returned, where a paragraph is defined as data followed by 2 or more successive newline characters (only 2 newlines are returned at the end of the returned data).

In any case, the end of the stream terminates the current line.

Raises EOFError when there is no more data in the stream. Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

NOTE: When sep_string is not `nil`, this method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 881
    def readlines(sep_string = $/)
      lines = []
      each_line(sep_string) { |line| lines << line }
      lines
    end

readpartial(length[, buffer]) → string or buffer click to toggle source

Returns at most length bytes from the data stream using only the internal read buffer if the buffer is not empty. Falls back to reading from the stream if the buffer is empty. Blocks if no data is available from either the internal read buffer or the data stream regardless of whether or not the data stream would block.

Raises EOFError when there is no more data in the stream. Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_read. Therefore, this method always blocks if unable to immediately return length bytes. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_read.

    # File lib/io/like.rb, line 905
    def readpartial(length, buffer = nil)
      # Check the validity of the method arguments.
      unless length >= 0 then
        raise ArgumentError, "negative length #{length} given"
      end
      buffer = '' if buffer.nil?
      # Flush the buffer.
      buffer.slice!(0..-1)

      # Read and return up to length bytes.
      if __io_like__internal_read_buffer.empty? then
        begin
          buffer << __io_like__buffered_read(length)
        rescue Errno::EAGAIN, Errno::EINTR
          retry if read_ready?
        end
      else
        raise IOError, 'closed stream' if closed?
        raise IOError, 'not opened for reading' unless readable?

        buffer << __io_like__internal_read_buffer.slice!(0, length)
      end
      buffer
    end

rewind → 0 click to toggle source

Sets the position of the file pointer to the beginning of the stream and returns 0 when complete. The lineno attribute is reset to 0 if successful and the stream is readable according to readable?.

As a side effect, the internal read and write buffers are flushed.

Raises IOError if closed? returns `true`. Raises Errno::ESPIPE unless seekable? returns `true`.

NOTE: Because this method relies on unbuffered_seek and unbuffered_write (when the internal write buffer is not empty), it will also raise the same errors and block at the same times as those functions.

    # File lib/io/like.rb, line 945
    def rewind
      seek(0, IO::SEEK_SET)
      self.lineno = 0 if readable?
      0
    end

seek(offset[, whence]) → 0 click to toggle source

Sets the current data position to offset based on the setting of whence. If whence is unspecified or IO::SEEK_SET, offset counts from the beginning of the data. If whence is IO::SEEK_END, offset counts from the end of the data (offset should be negative here). If whence is IO::SEEK_CUR, offset is relative to the current position.

As a side effect, the internal read and write buffers are flushed except when seeking relative to the current position (whence is IO::SEEK_CUR) to a location within the internal read buffer.

Raises IOError if closed? returns `true`. Raises Errno::ESPIPE unless seekable? returns `true`.

NOTE: Because this method relies on unbuffered_seek and unbuffered_write (when the internal write buffer is not empty), it will also raise the same errors and block at the same times as those functions.

    # File lib/io/like.rb, line 970
    def seek(offset, whence = IO::SEEK_SET)
      __io_like__buffered_seek(offset, whence)
      0
    end

seekable? → true or false click to toggle source

Returns `true` if the stream is seekable, `false` otherwise.

This implementation always returns `false` for duplexed objects and checks to see if unbuffered_seek is defined in order to make its determination otherwise. Override this if the implementing class always provides the unbuffered_seek method but may not always be seekable.

    # File lib/io/like.rb, line 984
    def seekable?
      ! duplexed? && respond_to?(:unbuffered_seek, true)
    end

sync → true or false click to toggle source

Returns true if the internal write buffer is currently being bypassed, false otherwise.

Raises IOError if closed? returns `true`.

    # File lib/io/like.rb, line 995
    def sync
      raise IOError, 'closed stream' if closed?
      @__io_like__sync ||= false
    end

sync = boolean → boolean click to toggle source

When set to `true` the internal write buffer will be bypassed. Any data currently in the buffer will be flushed prior to the next output operation. When set to `false`, the internal write buffer will be enabled.

Raises IOError if closed? returns `true`.

    # File lib/io/like.rb, line 1009
    def sync=(sync)
      raise IOError, 'closed stream' if closed?
      @__io_like__sync = sync ? true : false
    end

sysread(length) → string click to toggle source

Reads and returns up to length bytes directly from the data stream, bypassing the internal read buffer.

Returns `""` if length is 0 regardless of the status of the data stream. This is for compatibility with IO#sysread.

Raises EOFError if reading begins at the end of the stream. Raises IOError if the internal read buffer is not empty. Raises IOError if closed? returns `true`.

NOTE: Because this method relies on unbuffered_read, it will also raise the same errors and block at the same times as that function.

    # File lib/io/like.rb, line 1029
    def sysread(length, buffer = nil)
      buffer = buffer.nil? ? '' : buffer.to_str
      buffer.slice!(0..-1) unless buffer.empty?
      return buffer if length == 0

      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?
      unless __io_like__internal_read_buffer.empty? then
        raise IOError, 'sysread on buffered IO'
      end

      # Flush the internal write buffer for writable, non-duplexed objects.
      __io_like__buffered_flush if writable? && ! duplexed?

      buffer << unbuffered_read(length)
    end

sysseek(offset[, whence]) → integer click to toggle source

Sets the current data position to offset based on the setting of whence. If whence is unspecified or IO::SEEK_SET, offset counts from the beginning of the data. If whence is IO::SEEK_END, offset counts from the end of the data (offset should be negative here). If whence is IO::SEEK_CUR, offset is relative to the current position.

Raises IOError if the internal read buffer is not empty. Raises IOError if closed? returns `true`. Raises Errno::ESPIPE unless seekable? returns `true`.

NOTE: Because this method relies on unbuffered_seek, it will also raise the same errors and block at the same times as that function.

    # File lib/io/like.rb, line 1061
    def sysseek(offset, whence = IO::SEEK_SET)
      raise IOError, 'closed stream' if closed?
      raise Errno::ESPIPE unless seekable?
      unless __io_like__internal_read_buffer.empty? then
        raise IOError, 'sysseek on buffered IO'
      end
      unless __io_like__internal_write_buffer.empty? then
        warn('warning: sysseek on buffered IO')
      end

      unbuffered_seek(offset, whence)
    end

syswrite(string) → integer click to toggle source

Writes string directly to the data stream, bypassing the internal write buffer and returns the number of bytes written.

As a side effect for non-duplex objects, the internal read buffer is flushed.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: Because this method relies on unbuffered_write, it will also raise the same errors and block at the same times as that function.

    # File lib/io/like.rb, line 1088
    def syswrite(string)
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for writing' unless writable?
      unless __io_like__internal_write_buffer.empty? then
        warn('warning: syswrite on buffered IO')
      end

      # Flush the internal read buffer and set the unbuffered position to the
      # buffered position when dealing with non-duplexed objects.
      unless duplexed? || __io_like__internal_read_buffer.empty? then
        unbuffered_seek(-__io_like__internal_read_buffer.length, IO::SEEK_CUR)
        __io_like__internal_read_buffer.slice!(0..-1)
      end

      unbuffered_write(string)
    end

tell() click to toggle source
Alias for: pos
to_io → ios click to toggle source

Returns ios.

    # File lib/io/like.rb, line 1109
    def to_io
      self
    end

tty?() click to toggle source
Alias for: isatty
ungetc(integer) → nil click to toggle source

Calls unread with `integer.chr` as an argument.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

    # File lib/io/like.rb, line 1120
    def ungetc(integer)
      unread(integer.chr)
    end

unread(string) → nil click to toggle source

Pushes the given string onto the front of the internal read buffer and returns `nil`. If string is not a String, it is converted to one using its `to_s` method.

Raises IOError if closed? returns `true`. Raises IOError unless readable? returns `true`.

    # File lib/io/like.rb, line 1133
    def unread(string)
      raise IOError, 'closed stream' if closed?
      raise IOError, 'not opened for reading' unless readable?
      __io_like__internal_read_buffer.insert(0, string.to_s)
      nil
    end

writable? → true or false click to toggle source

Returns `true` if the stream is both open and writable, `false` otherwise.

This implementation checks to see if unbuffered_write is defined in order to make its determination. Override this if the implementing class always provides the unbuffered_write method but may not always be open in a writable mode.

    # File lib/io/like.rb, line 1170
    def writable?
      ! __io_like__closed_write? && respond_to?(:unbuffered_write, true)
    end

write(string) → integer click to toggle source

Writes the given string to the stream and returns the number of bytes written. If string is not a String, its `to_s` method is used to convert it into one. The entire contents of string are written, blocking as necessary even if the data stream does not block.

Raises IOError if closed? returns `true`. Raises IOError unless writable? returns `true`.

NOTE: This method ignores Errno::EAGAIN and Errno::EINTR raised by unbuffered_write. Therefore, this method always blocks if unable to immediately write string completely. Aside from that exception, this method will also raise the same errors and block at the same times as unbuffered_write.

    # File lib/io/like.rb, line 1190
    def write(string)
      string = string.to_s
      return 0 if string.empty?

      bytes_written = 0
      while bytes_written < string.length do
        begin
          bytes_written +=
            __io_like__buffered_write(string.to_s.slice(bytes_written..-1))
        rescue Errno::EAGAIN, Errno::EINTR
          retry if write_ready?
        end
      end
      bytes_written
    end

write_ready? → true or false click to toggle source

Returns `true` when the stream may be written without error, `false` otherwise. This method will block until one of the conditions is known.

This default implementation of write_ready? is a hack which should be able to work for both real IO objects and IO-like objects; however, it is inefficient since it merely sleeps for 1 second and then returns `true` as long as closed? returns `false`. IO.select should be used for real IO objects to wait for a writeable condition on platforms with support for IO.select. Other solutions should be found as necessary to improve this implementation on a case by case basis.

Basically, this method should be overridden in derivative classes.

    # File lib/io/like.rb, line 1155
    def write_ready?
      return false unless writable?
      sleep(1)
      true
    end

[Validate]

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