diff --git a/lib/cxl/cxl/lib/cxl.rb b/lib/cxl/cxl/lib/cxl.rb
index 8eee01b..31180bf 100644
--- a/lib/cxl/cxl/lib/cxl.rb
+++ b/lib/cxl/cxl/lib/cxl.rb
@@ -1,2 +1,17 @@
 require "cxl/cli"
+require "cxl/config"
+require "cxl/parser"
 require "cxl/version"
+
+module Cxl
+  class << self
+
+    def compile_to(input_fname, output_fname, cppflags)
+      parser = Parser.new(input_fname, cppflags)
+      parsed = parser.parse
+
+      0
+    end
+
+  end
+end
diff --git a/lib/cxl/cxl/lib/cxl/cli.rb b/lib/cxl/cxl/lib/cxl/cli.rb
index bb0b2c2..58fc458 100644
--- a/lib/cxl/cxl/lib/cxl/cli.rb
+++ b/lib/cxl/cxl/lib/cxl/cli.rb
@@ -29,6 +29,29 @@ EOF
           puts HELP_TEXT
           return 0
         end
+        if args.empty?
+          $stderr.puts "Error: specify input file(s)."
+          return 1
+        end
+        object_files = []
+        cppflags = []
+        args.each do |input_fname|
+          output_fname =
+            if opts[:compile_only] and opts[:output]
+              opts[:output]
+            else
+              input_fname.sub(%r{\.[^.]*$}, "") + ".o"
+            end
+          rv = Cxl.compile_to(input_fname, output_fname, cppflags)
+          if rv == 0
+            object_files << output_fname
+          else
+            return rv
+          end
+        end
+        unless opts[:compile_only]
+          #Cxl.link_to(object_files, opts[:output])
+        end
 
         0
       end
diff --git a/lib/cxl/cxl/lib/cxl/config.rb b/lib/cxl/cxl/lib/cxl/config.rb
index cf8ac9f..e0769ea 100644
--- a/lib/cxl/cxl/lib/cxl/config.rb
+++ b/lib/cxl/cxl/lib/cxl/config.rb
@@ -1,3 +1,5 @@
+require "singleton"
+
 module Cxl
   class Config
 
diff --git a/lib/cxl/cxl/lib/cxl/parser.rb b/lib/cxl/cxl/lib/cxl/parser.rb
new file mode 100644
index 0000000..a247130
--- /dev/null
+++ b/lib/cxl/cxl/lib/cxl/parser.rb
@@ -0,0 +1,25 @@
+require "open3"
+
+module Cxl
+  class Parser
+
+    def initialize(fname, cppflags)
+      @fname = fname
+      @cppflags = cppflags
+    end
+
+    def parse
+      c_preprocessor_command = Config.instance.c_preprocessor
+      command = c_preprocessor_command + @cppflags + [@fname]
+      pp_out, pp_err, status = Open3.capture3(*command)
+      if pp_err != ""
+        $stderr.write(pp_err)
+      end
+      if status != 0
+        return
+      end
+      puts pp_out.lines[0, 2]
+    end
+
+  end
+end