1 files changed, 93 insertions, 0 deletions
diff --git a/Library/Contributions/cmds/brew-unpack.rb b/Library/Contributions/cmds/brew-unpack.rb
new file mode 100755
index 000000000..d4d72623e
--- /dev/null
+++ b/Library/Contributions/cmds/brew-unpack.rb
@@ -0,0 +1,93 @@
+require 'formula'
+
+require 'stringio'
+module ScriptDataReader
+  # This module contains a method for extracting the contents of DATA from a
+  # Ruby file other than the script containing the currently executing
+  # function.  Many thanks to Glenn Jackman's Stackoverflow answer which
+  # provided this code:
+  #
+  #   http://stackoverflow.com/questions/2156629/can-i-access-the-data-from-a-required-script-in-ruby/2157556#2157556
+  def self.load(filename)
+    data = StringIO.new
+    File.open(filename) do |f|
+      begin
+        line = f.gets
+      end until line.nil? or line.match(/^__END__$/)
+      while line = f.gets
+        data << line
+      end
+    end
+    data.rewind
+    data
+  end
+end
+
+# Need to tweak the Formula class slightly so that patching is option and `DATA`
+# patches work correctly.
+class Formula
+  # Create a reference to the original Formula.patch method and then override
+  # so that paching only happens if the user asks.
+  alias do_patch patch
+  def patch
+    if ARGV.include? '--patch'
+      # Yes Ruby, we are about to redefine a constant. Just breathe.
+      orig_v = $VERBOSE; $VERBOSE = nil
+      Formula.const_set 'DATA', ScriptDataReader.load(path)
+      $VERBOSE = orig_v
+
+      do_patch
+    end
+  end
+
+  # handle_llvm_failure() requires extend/ENV, so let's never fail
+  # with llvm since we don't particularly care in this context.
+  def fails_with_llvm?; false; end
+end
+
+module Homebrew extend self
+  def unpack
+    unpack_usage = <<-EOS
+Usage: brew unpack [--patch] [--destdir=path/to/extract/in] <formulae ...>
+
+Unpack formulae source code for inspection.
+
+Formulae archives will be extracted to subfolders inside the current working
+directory or a directory specified by `--destdir`. If the `--patch` option is
+supplied, patches will also be downloaded and applied.
+    EOS
+
+    if ARGV.empty?
+      puts unpack_usage
+      exit 0
+    end
+
+    formulae = ARGV.formulae
+    raise FormulaUnspecifiedError if formulae.empty?
+
+    unpack_dir = ARGV.options_only.select {|o| o.start_with? "--destdir="}
+    if unpack_dir.empty?
+      unpack_dir = Pathname.new Dir.getwd
+    else
+      unpack_dir = Pathname.new(unpack_dir.first.split('=')[1]).realpath
+      unpack_dir.mkpath unless unpack_dir.exist?
+    end
+
+    raise "Cannot write to #{unpack_dir}" unless unpack_dir.writable?
+
+    formulae.each do |f|
+      # Create a nice name for the stage folder.
+      stage_dir = unpack_dir + [f.name, f.version].join('-')
+      raise "Destination #{stage_dir} allready exists!" if stage_dir.exist?
+
+      f.brew do
+        oh1 "Unpacking #{f.name} to: #{stage_dir}"
+        cp_r Dir.getwd, stage_dir
+      end
+    end
+  end
+end
+
+# Here is the actual code that gets run when `brew` loads this external
+# command.
+Homebrew.unpack