Ruby Yaml to Enum

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Generate Java 1.5 enums from a YAML file

!/bin/env ruby
Single value enums are frequently needed and they usually require additional code to lookup or access the enum
based on a value. This Ruby script generates a .java enum based on a YAML input file

require 'yaml' require 'erb'

def java_name(s)

   s.upcase.gsub('/', '_')

end

template = ERB.new <<-EOF package <%= @package %>;

public enum <%= @enum %> {

   EMPTY(""),<% @enums.each do |i| %>
   <%= java_name(i) %>("<%= i %>")<%= (i == @enums[-1]) ? ';' : ',' %><% end %>

   private final String value;

   <%= @enum %>(String value) {
       this.value = value;
   }

   @Override
   public String toString() {
       return value;
   }

   public static <%= @enum %> getValue(String value) {
       for (<%= @enum %> e : values()) {
           if (e.value.equals(value)) {
               return e;
           }
       }
       return EMPTY;
   }

}

EOF

if ARGV.size == 0 then

   srcDir = 'C:\\dev\\src\\java\\com'
   destDir = 'C:\\dev\\generated-src\\java\\com'

else

   srcDir = ARGV[0]
   destDir = ARGV[1]

end

class Fields

   attr_accessor :enums, :name, :package, :enum
   def initialize(file)
       @name = /(com.*)/.match( file.gsub('\\', '.').gsub('/', '.') )[1].gsub(/\.yml$/, '.java')
       @package = @name.split('.')[0..-3].join('.')
       @enum = @name.split('.')[-2]
   end
   # Support templating of member data.
   def get_binding
       binding
   end

end

if !File.directory?(destDir) then

   Dir.mkdir(destDir)

end

Dir.entries(srcDir).select{|f| File.file?(File.join(srcDir, f)) && File.extname(f) == ".yml" }.each do |f|

   file = File.join(srcDir, f)

   data = Fields.new(file)
   File.open( file, "r" ) do |yf|
       data.enums = YAML::load( yf )
       output = template.result(data.get_binding)
       destFile = File.join(destDir, data.enum + '.java')
       if !File.exists?(destFile) || File.read(destFile) != output then
           File.open(destFile, 'a+') do |dest|
               dest.write output
               dest.truncate(dest.pos)
           end
           puts "Updated #{destFile}"
       else
           puts "#{destFile} is up to date"
       end
   end

end </geshi>

Sample Colors.yml

 - red
 - green
 - blue