add build_dist.rb to create dist/rscons as a standalone script

.gitignore

@@ -3,5 +3,6 @@
 /_yardoc/
 /build_test_run/
 /coverage/
+/dist/
 /doc/
 /pkg/

Rakefile.rb

@@ -13,6 +13,10 @@ require "rake/clean"
 CLEAN.include %w[build_test_run .yardoc doc coverage]
 CLOBBER.include %w[pkg]
 
+task :build_dist do
+  sh "ruby build_dist.rb"
+end
+
 RSpec::Core::RakeTask.new(:spec, :example_string) do |task, args|
   if args.example_string
     ENV["partial_specs"] = "1"

build_dist.rb

@@ -0,0 +1,39 @@
+#!/usr/bin/env ruby
+
+require "fileutils"
+
+PROG_NAME = "rscons"
+START_FILE = "bin/#{PROG_NAME}"
+LIB_DIR = "lib"
+DIST = "dist"
+
+files_processed = {}
+
+process_file = lambda do |file, fh|
+  File.read(file, mode: "rb").each_line do |line|
+    if line =~ /^\s*require(?:_relative)?\s*"(.*)"$/
+      require_name = $1
+      if require_name =~ %r{^#{PROG_NAME}(?:/.*)?$}
+        path = "#{LIB_DIR}/#{require_name}.rb"
+        if File.exists?(path)
+          unless files_processed[path]
+            files_processed[path] = true
+            process_file[path, fh]
+          end
+        else
+          raise "require path #{path.inspect} not found"
+        end
+      else
+        fh.write(line)
+      end
+    else
+      fh.write(line)
+    end
+  end
+end
+
+FileUtils.mkdir_p(DIST)
+
+File.open("#{DIST}/#{PROG_NAME}", "wb", 0755) do |fh|
+  process_file[START_FILE, fh]
+end