Add USE flag list generator, ignore result file

.gitignore

@@ -0,0 +1 @@
+files/packages/use.json

bin/use-index.rb

@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+
+require 'json'
+
+GLOBAL = '/usr/portage/profiles/use.desc'
+LOCAL  = '/usr/portage/profiles/use.local.desc'
+
+output = { 'global' => {}, 'local' => {} }
+
+File.readlines(GLOBAL).each do |line|
+  next if line =~ /^(|#.*)$/
+
+  flag, desc = line.strip.split(' - ', 2)
+  output['global'][flag] = desc
+end
+
+File.readlines(LOCAL).each do |line|
+  next if line =~ /^(|#.*)$/
+
+  atom_flag, desc = line.strip.split(' - ', 2)
+  atom, flag      = atom_flag.split(':', 2)
+  cat, pkg        = atom.split('/', 2)
+
+  output['local'][cat]          ||= {}
+  output['local'][cat][pkg]     ||= {}
+  output['local'][cat][pkg][flag] = desc
+end
+
+puts output.to_json