Class: MARC::XMLReader

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/marc/xmlreader.rb

Overview

the constructor which you can pass either a filename:

reader = MARC::XMLReader.new('/Users/edsu/marc.xml')

or a File object, 

reader = Marc::XMLReader.new(File.new('/Users/edsu/marc.xml'))

or really any object that responds to read(n)

reader = MARC::XMLReader.new(StringIO.new(xml))

By default, XMLReader uses REXML’s pull parser, but you can swap that out with Nokogiri or jrexml (or let the system choose the ‘best’ one). The :parser can either be one of the defined constants or the constant’s value.

reader = MARC::XMLReader.new(fh, :parser=>'magic')

It is also possible to set the default parser at the class level so all subsequent instances will use it instead:

MARC::XMLReader.best_available
"nokogiri" # returns parser name, but doesn't set it.

Use:

MARC::XMLReader.best_available!

or

MARC::XMLReader.nokogiri!

Constant Summary collapse

USE_BEST_AVAILABLE = 
'magic'
USE_REXML = 
'rexml'
USE_NOKOGIRI = 
'nokogiri'
USE_JREXML = 
'jrexml'
USE_JSTAX = 
'jstax'
USE_LIBXML = 
'libxml'
@@parser = 
USE_REXML

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file, options = {}) ⇒ XMLReader

Returns a new instance of XMLReader.



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# File 'lib/marc/xmlreader.rb', line 46

def initialize(file, options = {})
  if file.is_a?(String)
    handle = File.new(file)
  elsif file.respond_to?("read", 5)
    handle = file
  else
    raise ArgumentError, "must pass in path or File"
  end
  @handle = handle

  if options[:parser]
    parser = self.class.choose_parser(options[:parser].to_s)
  else
    parser = @@parser
  end
  case parser
  when 'magic' then extend MagicReader
  when 'rexml' then extend REXMLReader
  when 'jrexml' then 
    raise ArgumentError, "jrexml only available under jruby" unless defined? JRUBY_VERSION
    extend JREXMLReader
  when 'nokogiri' then extend NokogiriReader    
  when 'jstax' then 
    raise ArgumentError, "jstax only available under jruby" unless defined? JRUBY_VERSION
    extend JRubySTAXReader
  when 'libxml' then extend LibXMLReader
    raise ArgumentError, "libxml not available under jruby" if defined? JRUBY_VERSION
  end
end

Instance Attribute Details

#parser ⇒ Object (readonly)

Returns the value of attribute parser.



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# File 'lib/marc/xmlreader.rb', line 44

def parser
  @parser
end

Class Method Details

.best_available ⇒ Object

Returns the value of the best available parser



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# File 'lib/marc/xmlreader.rb', line 97

def self.best_available
  parser = nil
  jruby = [USE_NOKOGIRI, USE_JSTAX, USE_JREXML]
  ruby = [USE_NOKOGIRI, USE_LIBXML]
  if defined? JRUBY_VERSION
    unless parser
      begin
        require 'nokogiri'
        parser = USE_NOKOGIRI              
      rescue LoadError
      end
    end
    unless parser
      begin
        # try to find the class, so we throw an error if not found
        java.lang.Class.forName("javax.xml.stream.XMLInputFactory") 
        parser = USE_JSTAX
      rescue java.lang.ClassNotFoundException
      end
    end
    unless parser
      begin
        require 'jrexml'
        parser = USE_JREXML    
      rescue LoadError                        
      end
    end              
  else
    begin
      require 'nokogiri'
      parser = USE_NOKOGIRI        
    rescue LoadError          
    end
    unless defined? JRUBY_VERSION
      unless parser
        begin
          require 'xml'
          parser = USE_LIBXML
        rescue LoadError
        end
      end        
    end
  end
  parser = USE_REXML unless parser
  parser
end

.best_available! ⇒ Object

Sets the best available parser as the default



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# File 'lib/marc/xmlreader.rb', line 145

def self.best_available!
  @@parser = self.best_available
end

.jrexml! ⇒ Object

Sets jrexml as the default parser



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# File 'lib/marc/xmlreader.rb', line 155

def self.jrexml!
  @@parser = USE_JREXML
end

.nokogiri! ⇒ Object

Sets Nokogiri as the default parser



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# File 'lib/marc/xmlreader.rb', line 150

def self.nokogiri!
  @@parser = USE_NOKOGIRI
end

.parser ⇒ Object

Returns the currently set parser type



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# File 'lib/marc/xmlreader.rb', line 77

def self.parser
  return @@parser
end

.parser=(p) ⇒ Object

Sets the class parser



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# File 'lib/marc/xmlreader.rb', line 92

def self.parser=(p)
  @@parser = choose_parser(p)
end

.parsers ⇒ Object

Returns an array of all the parsers available



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# File 'lib/marc/xmlreader.rb', line 82

def self.parsers
  p = []
  self.constants.each do | const |
    next unless const.match("^USE_")
    p << const
  end      
  return p
end

.rexml! ⇒ Object

Sets REXML as the default parser



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# File 'lib/marc/xmlreader.rb', line 160

def self.rexml!
  @@parser = USE_REXML
end