1 files changed, 60 insertions, 24 deletions
diff --git a/ext/ripper/tools/preproc.rb b/ext/ripper/tools/preproc.rb
index a2dba36e02..4b26c5bcb0 100755
--- a/ext/ripper/tools/preproc.rb
+++ b/ext/ripper/tools/preproc.rb
@@ -1,56 +1,92 @@
+# $Id$
+
+require 'stringio'
+require 'optparse'
+
 def main
-  prelude
-  grammar
-  usercode
+  output = nil
+  parser = OptionParser.new
+  parser.banner = "Usage: #{File.basename($0)} [--output=PATH] <parse.y>"
+  parser.on('--output=PATH', 'An output file.') {|path|
+    output = path
+  }
+  parser.on('--help', 'Prints this message and quit.') {
+    puts parser.help
+    exit 0
+  }
+  begin
+    parser.parse!
+  rescue OptionParser::ParseError => err
+    $stderr.puts err.message
+    $stderr.puts parser.help
+    exit 1
+  end
+  unless ARGV.size == 1
+    $stderr.puts "wrong number of arguments (#{ARGV.size} for 1)"
+    exit 1
+  end
+  out = StringIO.new
+  File.open(ARGV[0]) {|f|
+    prelude f, out
+    grammar f, out
+    usercode f, out
+  }
+  if output
+    File.open(output, 'w') {|f|
+      f.write out.string
+    }
+  else
+    print out.string
+  end
 end
 
-def prelude
-  while line = ARGF.gets
+def prelude(f, out)
+  while line = f.gets
     case line
     when %r</\*%%%\*/>
-      puts '/*'
+      out.puts '/*'
     when %r</\*%>
-      puts '*/'
+      out.puts '*/'
     when %r<%\*/>
-      puts
+      out.puts
     when /\A%%/
-      puts '%%'
+      out.puts '%%'
       return
     when /\A%token/
-      puts line.sub(/<\w+>/, '<val>')
+      out.puts line.sub(/<\w+>/, '<val>')
     when /\A%type/
-      puts line.sub(/<\w+>/, '<val>')
+      out.puts line.sub(/<\w+>/, '<val>')
     else
-      print line
+      out.print line
     end
   end
 end
 
-def grammar
-  while line = ARGF.gets
+def grammar(f, out)
+  while line = f.gets
     case line
     when %r</\*%%%\*/>
-      puts '#if 0'
+      out.puts '#if 0'
     when %r</\*%c%\*/>
-      puts '/*'
+      out.puts '/*'
     when %r</\*%c>
-      puts '*/'
+      out.puts '*/'
     when %r</\*%>
-      puts '#endif'
+      out.puts '#endif'
     when %r<%\*/>
-      puts
+      out.puts
     when /\A%%/
-      puts '%%'
+      out.puts '%%'
       return
     else
-      print line
+      out.print line
     end
   end
 end
 
-def usercode
-  while line = ARGF.gets
-    print line
+def usercode(f, out)
+  while line = f.gets
+    out.print line
   end
 end