Class: IO

Inherits:
Object
  • Object
show all
Defined in:
lib/sixarm_ruby_magic_number_type/io.rb

Instance Method Summary collapse

Instance Method Details

#magic_number_type(bytes = self.read(String::MagicNumberTypeMaxLength)) ⇒ Object

Detect the data type by checking various “magic number” conventions for the introductory bytes of a data stream

Return the “magic number” as a symbol:

- :bitmap = Bitmap image file, typical extension ".bmp"
- :gzip = Unix GZIP compressed data, typical extension ".gz"
- :postscript = Postscript pages, typical extension ".ps"

Return nil if there’s no match for any known magic number.

Example:

IO.f = File.open("test.ps","rb")
put f.magic_number(s)
=> :postscript

See:

- IO::MagicNumberTypeHash
- File.magic_number_type

TODO change from hash implementation to binary tree



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# File 'lib/sixarm_ruby_magic_number_type/io.rb', line 26

def magic_number_type(bytes=self.read(String::MagicNumberTypeMaxLength))
  String::MagicNumberTypeHash.each_pair do |byte_string,type_symbol|
    return type_symbol if byte_string==bytes[0,byte_string.length]
  end
  return nil
end