[RegEx: Convert print to print()] Functions to convert between Python 2 and Py3k print statements.Supports string interpolation and multiline strings. Does *NOT* cover Python 2 backslash line continuations completely (yet). I originally wrote it for use in a ruble command in Eclipse Aptana Studio 3. #regex #conversion #python #python3 #ruby #rub…

python_py3k_print_convert.rb

# -*- coding: utf-8 -*-
# 
#  == Aptana Ruble Commands
#  Convert Between Python 2 and Py3k Print Statements
#  
#   Created by André Berg on 2013-05-23.
#   Copyright 2013 Berg Media. All rights reserved.
#  
#   Used from a Python.ruble command in Eclipse 
#   Aptana Studio 3:
#  
#   command t(:convert_to_py3k_print) do |cmd|
#     cmd.output = :replace_selection
#     cmd.input = :selection
#     cmd.invoke do |context|
#       text = "#{STDIN.read}"
#       convert_to_py3k_print(text)
#     end
#   end

=begin rdoc
 Convert Python 2 <tt>print ...</tt> statements in +text+ to Python 3 <tt>print(...)</tt> format.
 
 Supports string interpolation and multiline strings.
=end
def convert_to_py3k_print(text)
  regex_print_descriptor = /print(\s*)>>(\s*)(.+),\s*(.+)/
  regex_print_simple = /print\s+(?![\'\"])([^#\n\r]+(?<! ))?/
  regex_print_multiline = /print\s+(ur|ru)?(['"]{1,3})([\w\W]+?)(\2)([^#\n\r]+(?<! ))?/m
  regex_print = /print\s+(ur|ru)?(['"])(?!\2)([^\r\n]+)(\2)([^#\n\r]+(?<! ))?/
  result = text.gsub(regex_print_descriptor, "print(\\4, file=\\3)")
  result.gsub!(regex_print, "print(\\1\\2\\3\\4\\5)")
  result.gsub!(regex_print_simple, "print(\\1)")
  result.gsub!(regex_print_multiline, "print(\\1\\2\\3\\4\\5)")
  result
end

=begin rdoc
 Convert Python 3 <tt>print(...)</tt> statements in +text+ to Python 2 <tt>print ... </tt> format.
 
 Supports string interpolation and multiline strings.
=end
def convert_from_py3k_print(text) 
  regex_print_descriptor = /print\((.+),(\s*)file=(.+)([^#\n\r]+(?<! ))?\)/
  regex_print = /print\(([\w\W]+?)\)(%\s*#.*[\r\n])?([^#\n\r]+(?<! ))?/m
  regex_line_continuation_fix = /(print\s+.+)%(\s*)(\s*#.*)?([\n\r])(.+)/m
  result = text.gsub(regex_print_descriptor, "print >> \\3,\\2\\1")
  result.gsub!(regex_print, "print \\1\\2\\3")
  result.gsub!(regex_line_continuation_fix, "\\1%\\2\\\\\\4\\5  \\3")
  result.rstrip
end

    
if __FILE__ == $0
  
  require "test/unit"

  class TestConvertPythonPrint < Test::Unit::TestCase
    def test_convert_to_py3k_print
      pairs = [
          {:python3 => 'print("bla bla", file=sys.stdout)',
           :python2 => 'print >> sys.stdout, "bla bla"'},
          {:python3 => 'print("bla bla".upper(), file=sys.stdout)',
           :python2 => 'print >> sys.stdout, "bla bla".upper()'},
          {:python3 => 'print("bla %s" % ("bla"), file=sys.stdout)',
           :python2 => 'print >> sys.stdout, "bla %s" % ("bla")'},
          {:python3 => 'print("bla bla".upper(), file=sys.stdout)',
           :python2 => 'print >> sys.stdout, "bla bla".upper()'},
          {:python3 => 'print("bla %s" % ("bla"), file=sys.stdout)',
           :python2 => 'print >> sys.stdout, "bla %s" % ("bla")'},
          {:python3 => 'print("bla %s" % "bla", file=sys.stdout)',     
           :python2 => 'print >> sys.stdout, "bla %s" % "bla"'},
          {:python3 => 'print("%r" % adapter)',                        
           :python2 => 'print "%r" % adapter'},
          {:python3 => 'print("{0!r}".format("bla"))',                 
           :python2 => 'print "{0!r}".format("bla")'},
          {:python3 => '   print("{0!r}".format(bla)) # comment',      
           :python2 => '   print    "{0!r}".format(bla) # comment'},
          {:python3 => '   print("{0!r}".format(bla, bla)) # comment', 
           :python2 => '   print    "{0!r}".format(bla, bla) # comment'},
          {:python3 => '   print("%r" % (bla, bla)) # comment',        
           :python2 => '   print    "%r" % (bla, bla) # comment'},
          {:python3 => '   print(variable)   # comment',               
           :python2 => '   print(variable)   # comment'},
          {:python3 => '   print(variable)  # comment',                
           :python2 => '   print  variable  # comment'},
          {:python3 => '   print("""{0}
           bla
           bla""".format("bla"))  # comment', 
           :python2 => '   print """{0}
           bla
           bla""".format("bla")  # comment'},
          {:python3 => '   print("""
           bla
           bla""")  # comment',
           :python2 => '   print """
           bla
           bla"""  # comment'},
          {:python3 => '   print("""%s
           bla
           bla""" % (bla, bla))  # comment', 
           :python2 => '   print """%s
           bla
           bla""" % (bla, bla)  # comment'}
        ]
        pairs.each do |pair|
          assert_equal(pair[:python3], convert_to_py3k_print(pair[:python2]))
        end
        
    end
    
    def test_convert_from_py3k_print
      pairs = [
        {:python3 => 'print("bla bla", file=sys.stdout)',            
         :python2 => 'print >> sys.stdout, "bla bla"'},
        {:python3 => 'print("bla bla".upper(), file=sys.stdout)',   
         :python2 => 'print >> sys.stdout, "bla bla".upper()'},
        {:python3 => 'print("bla %s" % ("bla"), file=sys.stdout)',   
         :python2 => 'print >> sys.stdout, "bla %s" % ("bla")'},
        {:python3 => 'print("bla bla".upper(), file=sys.stdout)',    
         :python2 => 'print >> sys.stdout, "bla bla".upper()'},
        {:python3 => 'print("bla %s" % ("bla"), file=sys.stdout)',   
         :python2 => 'print >> sys.stdout, "bla %s" % ("bla")'},
        {:python3 => 'print("bla %s" % "bla", file=sys.stdout)',     
         :python2 => 'print >> sys.stdout, "bla %s" % "bla"'},
        {:python3 => 'print("bla %s" % "bla", file=sys.stdout) # comment',     
         :python2 => 'print >> sys.stdout, "bla %s" % "bla" # comment'},
        {:python3 => 'print("%r" % adapter)',                        
         :python2 => 'print "%r" % adapter'},
        {:python3 => 'print("{0!r}".format("bla"))',                 
         :python2 => 'print "{0!r}".format("bla")'},
        {:python3 => '   print("{0!r}".format(bla)) # comment',      
         :python2 => '   print "{0!r}".format(bla) # comment'},
        {:python3 => '   print("{0!r}".format(bla, bla)) # comment', 
         :python2 => '   print "{0!r}".format(bla, bla) # comment'},
        {:python3 => '   print("%r" % (bla, bla)) # comment',        
         :python2 => '   print "%r" % (bla, bla) # comment'},
        {:python3 => '   print(variable)   # comment',               
         :python2 => '   print variable   # comment'},
        {:python3 => '   print(variable)  # comment',                
         :python2 => '   print variable  # comment'},
        {:python3 => '   print("""{0}
         bla
         bla""".format("bla"))  # comment', 
         :python2 => '   print """{0}
         bla
         bla""".format("bla")  # comment'},
        {:python3 => '   print("""
         bla
         bla""")  # comment',
         :python2 => '   print """
         bla
         bla"""  # comment'},
        {:python3 => '   print("""%s
         bla
         bla""" % (bla, bla))  # comment', 
         :python2 => '   print """%s
         bla
         bla""" % (bla, bla)  # comment'},
        {:python3 => 'print("Mode is %r and file already has %r, skipping..." % 
                              (self.mapfile.mode, k))',              
         :python2 => 'print "Mode is %r and file already has %r, skipping..." % \
                              (self.mapfile.mode, k)'},
        {:python3 => 'print("Mode is %r and file already has %r, skipping..." % # comment
                              (self.mapfile.mode, k))',              
         :python2 => 'print "Mode is %r and file already has %r, skipping..." % \
                              (self.mapfile.mode, k)  # comment'}
      ]
      pairs.each do |pair|
        assert_equal(pair[:python2], convert_from_py3k_print(pair[:python3]))
      end
    end
  end
end