Hi all,
What's the deal with all the different versions of
Pattern Matching on the
web? I've found that the most complete document and most helpful on
this sort of Ruby regular expression tutelage.
It seems like documentation on adopting sed to Ruby would be helpful.
[I'll write something if I ever understand it.]
Surprise: I'm trying to adapt some sed scripts into Ruby programs. I'd
like feedback on how to make them more idiomatic/Rubylicious and help
on making 2nd one work.
Here's my essential program for a line of sed that seems to work
correctly. I dunno if there's a better way to express it:
···
---------------------------------------------------
sed:
s/MATCH/GLOBAL REPLACEMENT/g
ruby:
#!/usr/bin/env ruby
files = ARGV
files.each do |arg|
f = File.open(arg)
puts "\nOpening file #{f}"
working_file = f.read
working_file.gsub!(/MATCH/,'GLOBAL REPLACEMENT')
puts "\nDoing ACTION in #{arg}"
f = File.new(arg, "w")
puts "\nWriting #{f} now"
f.print(working_file)
f.close
end
---------------------------------------------------
Here's the one I have problems with (we had a working Perl equivalent
but are trying to abandon Perl).
sed:
/BEGIN RANGE/,/END RANGE/{
s/MATCH/REPLACEMENT/g
}
ruby:
[same beginning]
if working_file =~ /BEGIN RANGE/ .. working_file =~ /END RANGE/
# INCLUSIVE use ... if you want non inclusive
working_file.sub!(/MATCH/,'REPLACEMENT')
end
[same ending]
-----------------
The above works fine on the first occurence of MATCH but won't do any of
the subsequent matches in the document. I subsitute 'gsub' but that
will just effect all of the places in the document, ignoring my if
statement. Suspecting a lack of understanding of the way the range
works and find and old thread on the mailing list
( http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/73674 )
but don't really follow it.
I've come up with the following as a tentative replacement but it's not
setting 'aline' in 'working_file' after it substitues it.
[same beginning]
working_file.each do |aline| # Read each line, right?
if aline =~ /BEGIN RANGE/ .. aline =~ /# end of CellContent/
aline.sub!(/Cell/,'CellHeading2')
end
end
[same ending]
-----------------
[Running up against my own ignorance now of the range thingie]
Here's my failing test:
#!/usr/bin/env ruby
files = ARGV
files.each do |arg|
f = File.open(arg)
puts "\nOpening file #{f}"
working_file = f.read
puts "Subsitutions occuring now"
working_file.each do |aline|
if aline =~ /BEGIN RANGE/ .. aline =~ /END RANGE/
aline.sub!(/MATCH/,'REPLACEMENT')
puts "#{aline}"
end
end
puts "\nOutput of working_file"
puts "#{working_file}"
puts "\nDoing ACTION in #{arg}"
f = File.new(arg, "w")
puts "\nWriting #{f} now"
f.print(working_file)
f.close
end
-----------------
Here's the test file:
a lonely line
BEGIN RANGE
MATCH
END RANGE
another lonely line
BEGIN RANGE
MATCH
nothing here
MATCH
END RANGE
don't change MATCH
-----------------
Here's the output:
,rtest2 ,test.txt
Opening file #<File:0xff3f0>
Subsitutions occuring now
BEGIN RANGE
REPLACEMENT
END RANGE
BEGIN RANGE
REPLACEMENT
nothing here
REPLACEMENT
END RANGE
Output of working_file
a lonely line
BEGIN RANGE
MATCH
END RANGE
another lonely line
BEGIN RANGE
MATCH
nothing here
MATCH
END RANGE
don't change MATCH
Doing ACTION in ,test.txt
Writing #<File:0xfeef8> now
Thanks for your help,
Keith
