refactor some Program functionality into Environment#build_sources()

lib/rscons/builders/program.rb

@@ -15,17 +15,8 @@ module Rscons
     end
 
     def run(target, sources, cache, env)
-      # convert sources to object file names
+      # build sources to linkable objects
-      objects = sources.map do |source|
+      objects = env.build_sources(sources, [env['OBJSUFFIX'], env['LIBSUFFIX']].flatten, cache)
-        if source.has_suffix?([env['OBJSUFFIX'], env['LIBSUFFIX']])
-          source
-        else
-          o_file = env.get_build_fname(source, env['OBJSUFFIX', :string])
-          builder = env.builders.values.find { |b| b.produces?(o_file, source, env) }
-          builder or raise "No builder found to convert input source #{source.inspect} to an object file."
-          builder.run(o_file, [source], cache, env) or break
-        end
-      end
       if objects
         use_cxx = sources.map do |s|
           s.has_suffix?(env['CXXSUFFIX'])

lib/rscons/environment.rb

@@ -228,5 +228,32 @@ module Rscons
       end
       deps
     end
+
+    # Build a list of source files into files containing one of the suffixes
+    # given by suffixes.
+    # This method is used internally by RScons builders.
+    # @param sources [Array] List of source files to build.
+    # @param suffixes [Array] List of suffixes to try to convert source files into.
+    # @param cache [Cache] The Cache.
+    # Return a list of the converted file names.
+    def build_sources(sources, suffixes, cache)
+      sources.map do |source|
+        if source.has_suffix?(suffixes)
+          source
+        else
+          converted = nil
+          suffixes.each do |suffix|
+            converted_fname = get_build_fname(source, suffix)
+            builder = @builders.values.find { |b| b.produces?(converted_fname, source, self) }
+            if builder
+              converted = builder.run(converted_fname, [source], cache, self)
+              return nil unless converted
+              break
+            end
+          end
+          converted or raise "Could not find a builder to handle #{source.inspect}."
+        end
+      end
+    end
   end
 end