Generates a naïve umbrella header by assuming every header in the working folder or any of its subfolders is public and should be included

generate_umbrella.rb

#!/usr/bin/env ruby

# Your umbrella header needs a comment in it like the below so this script
# knows which parts to replace
#
# /* IMPORTS BEGIN */
#
# /* IMPORTS END */

MODULE = ARGV[0] || File.basename(Dir.getwd)
MODULE_HEADER = "#{MODULE}.h"
REPLACEMENT_TAGS = /\/\* IMPORTS BEGIN \*\/.*\/\* IMPORTS END \*\//m

imports = Dir.glob("**/*.h").select { |f| File.basename(f) != MODULE_HEADER }
  .map { |f| "#import <#{MODULE}/#{File.basename(f)}>" }
  .join("\n")

imports = "/* IMPORTS BEGIN */\n#{imports}\n/* IMPORTS END */"
header = File.read(MODULE_HEADER)
imports = header.gsub(REPLACEMENT_TAGS, imports)

File.write(MODULE_HEADER, imports)