Class: File

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

Overview

Extend File with some BOM-Handling.

Constant Summary collapse

BOM_LIST_hex =

BOMs for different encodings.

{
  'UTF_8'      => "\xEF\xBB\xBF", #"\uEFBBBF"

  'UTF_16BE' => "\xFE\xFF", #"\uFEFF",

  'UTF_16LE' => "\xFF\xFE",
  'UTF_32BE' => "\x00\x00\xFE\xFF",
  'UTF_32LE' => "\xFE\xFF\x00\x00",
}

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.open(filename, mode_string = 'r', options = {}, &block) ⇒ Object

Redefine open to support BOM.

This modification allow the usage of encodings like “utf-8-bom”. This encodings can be used in read- and write-mode.

Examples:

File.open("file.txt", "w:utf-16le-bom"){|f|
  f << 'some content'
}
File.open("file.txt", "w:utf-16le", :bom => true ){|f|
  f << 'some content'
}

Remark

Ruby 1.9.2 supports already BOMs in read mode (e.g. “r:bom|utf-8”).

The syntactical difference (uft-8-bom instead bom|utf-8) is wanted to separate the two logics.

  • This gem does not support ruby 1.8 (makes no sense, you may store the BOM, but the conntent will not ne unicode).

  • This gem supports also BOMs in write mode.



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# File 'lib/file_with_bom.rb', line 103

def open(filename, mode_string = 'r', options = {}, &block)
  #~ puts "! %-10s %-20s %s" % [mode_string, filename, options.inspect] #only for tests

  
  #check for bom-flag in mode_string

  options[:bom] = true if mode_string.sub!('-bom','')
  
  f = open_old(filename, mode_string, options)
    
  if options[:bom]
    case mode_string
      when /\Ar/   #read mode -> remove BOM

        #remove BOM

        bom = f.read(f.utf_bom_hex.bytesize) 
        #check, if it was really a bom

        if bom != f.utf_bom_hex
          f.rewind  #return to position 0 if BOM was no BOM

        end
      when /\Aw/  #write mode -> attach BOM

        f << f.utf_bom_hex
    end #mode_string

  end
  
  if block_given?
    yield f 
    f.close
  end
end

.open_old ⇒ Object

Store the old File.open



77
 
# File 'lib/file_with_bom.rb', line 77

alias :open_old :open

Instance Method Details

#utf_bom_hex(encoding = external_encoding) ⇒ Object

Get BOM for the ‘external_encoding’.

You may use it like this:

File.open(filename, "w:utf-16le"){|f|
  f << f.utf_bom  #add the BOM manual
  f << 'some content'
}



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# File 'lib/file_with_bom.rb', line 71

def utf_bom_hex(encoding = external_encoding )
  BOM_LIST_hex[encoding].force_encoding(encoding) #ruby 1.9

end