Detect generated source maps

lib/linguist/generated.rb

@@ -58,6 +58,7 @@ module Linguist
       godeps? ||
       generated_by_zephir? ||
       minified_files? ||
+      source_map? ||
       compiled_coffeescript? ||
       generated_parser? ||
       generated_net_docfile? ||
@@ -96,6 +97,20 @@ module Linguist
       end
     end
 
+    # Internal: Is the blob a generated source map?
+    #
+    # Source Maps usually have .css.map or .js.map extensions. In case they
+    # are not following the name convention, detect them based on the content.
+    #
+    # Returns true or false.
+    def source_map?
+      return false unless extname.downcase == '.map'
+
+      name =~ /(\.css|\.js)\.map$/i ||                 # Name convention
+      lines[0] =~ /^{"version":\d+,/ ||                # Revision 2 and later begin with the version number
+      lines[0] =~ /^\/\*\* Begin line maps\. \*\*\/{/  # Revision 1 begins with a magic comment
+    end
+
     # Internal: Is the blob of JS generated by CoffeeScript?
     #
     # CoffeeScript is meant to output JS that would be difficult to