Module: External::Utils

Defined in:
lib/external/utils.rb,
lib/external/patches/windows_utils.rb

Class Method Summary collapse

Class Method Details

.file_length(io) ⇒ Object

Modfied to properly determine file lengths on Windows. Uses code from ‘win32/file/stat’ (rubyforge.org/projects/win32utils/)



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# File 'lib/external/patches/windows_utils.rb', line 10

def file_length(io)
  io_length(io)
end

.file_mode(io) ⇒ Object 



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# File 'lib/external/utils.rb', line 113

def file_mode(io)
  io_mode(io)
end

.io_length(io) ⇒ Object

Returns the length of the input IO



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# File 'lib/external/utils.rb', line 108

def io_length(io)
  io.fsync
  io.stat.size
end

.io_mode(io) ⇒ Object

Returns an array of bools determining if the input Io is readable and writable.



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# File 'lib/external/utils.rb', line 83

def io_mode(io)
  begin
    dup = io.dup
    
    # determine readable/writable by sending close methods
    # to the duplicated Io.  If the io cannot  be closed for 
    # read/write then it will raise an error, indicating that 
    # it was not open in the given mode.   
    [:close_read, :close_write].collect do |method|
      begin
        dup.send(method)
        true
      rescue(IOError)
        false
      end
    end
  ensure
    # Be sure that the dup is fully closed before proceeding!  
    # (Otherwise Tempfiles will not be properly disposed of
    # ... at least on Windows, perhaps on others)
    dup.close if dup && !dup.closed?
  end
end

.length(io) ⇒ Object

Determines the length of the input io using the _length method for the input io class. Non-External::Io inputs are extended in this process.

The _length method takes the input io, and should return the current length of the input io (ie a flush operation may be required).

See try_handle for more details.



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# File 'lib/external/utils.rb', line 72

def length(io)
  case io
  when Io then try_handle(io, "length")
  else
    io.extend Io
    io.length
  end
end

.mode(io) ⇒ Object

Determines the generic mode of the input io using the _mode method for the input io class. By default Io provides _mode methods for File, Tempfile, and StringIo. The return string is determined as follows:

readable & writable

r+

readable

r

writable

w

The _mode method takes the input io and should return an array specifying whether or not io is readable and writable (ie [readable, writable]).

See try_handle for more details.



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# File 'lib/external/utils.rb', line 50

def mode(io) 
  readable, writable = try_handle(io, "mode")

  case
  when readable && writable then "r+"
  when readable then "r"
  when writable then "w"
  else
    # occurs for r+ mode, for some reason
    "r+"
  end
end

.stringio_length(io) ⇒ Object

Returns the length of the input StringIo

s = StringIo.new("abcde", "r+")
External::Io.length(s)  # => 5



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# File 'lib/external/utils.rb', line 147

def stringio_length(io)
  io.string.length
end

.stringio_mode(io) ⇒ Object

Returns an array of bools determining if the input StringIo is readable and writable.

s = StringIo.new("abcde", "r+")
External::Io.stringio_mode(s)  # => [true, true]



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# File 'lib/external/utils.rb', line 138

def stringio_mode(io)
  [!io.closed_read?, !io.closed_write?]
end

.tempfile_length(io) ⇒ Object

Returns the length of the input Tempfile



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# File 'lib/external/utils.rb', line 128

def tempfile_length(io)
  file_length(io)
end

.tempfile_mode(io) ⇒ Object

Returns an array of bools determining if the input Tempfile is readable and writable.



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# File 'lib/external/utils.rb', line 123

def tempfile_mode(io)
  file_mode(io.instance_variable_get(:@tmpfile))
end

.try_handle(io, method) ⇒ Object

try_handle is a forwarding method allowing External::IO to handle non-File, non-Tempfile IO objects. try_handle infers a method name based on the class of the input and trys to forward the input io to that method within External::IO. For instance:

  • the _mode method for StringIO is ‘stringio_mode’

  • the _length method for StringIO is ‘stringio_length’

Nested classes have ‘::’ replaced by ‘_’. Thus to add support for Some::Unknown::IO, extend External::IO as below:

module External::IO
  def some_unknown_io_mode(io)
  ...
  end

  def some_unknown_io_length(io)
  ...
  end
end

See stringio_mode and stringio_length for more details.



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# File 'lib/external/utils.rb', line 27

def try_handle(io, method)
  method_name = io.class.to_s.downcase.gsub(/::/, "_") + "_#{method}"
  if Utils.respond_to?(method_name)
    Utils.send(method_name, io)
  else
    raise "cannot determine #{method} for '%s'" % io.class
  end
end