Add GitRepositoryExtension

Add an extension for accessing Git-related meta data that can be mixed
in into a Pathname object (e.g. `HOMBREW_REPOSITORY` or the path of a
`Tap` instance). The goal here is to eliminate code duplication.

2 files changed, 48 insertions, 0 deletions

diff --git a/Library/Homebrew/extend/git_repository.rb b/Library/Homebrew/extend/git_repository.rb
new file mode 100644
index 000000000..c15988550
--- /dev/null
+++ b/Library/Homebrew/extend/git_repository.rb
@@ -0,0 +1,47 @@
+require "utils/git"
+require "utils/popen"
+
+module GitRepositoryExtension
+  def git?
+    join(".git").exist?
+  end
+
+  def git_origin
+    return unless git? && Utils.git_available?
+    cd do
+      Utils.popen_read("git", "config", "--get", "remote.origin.url").chuzzle
+    end
+  end
+
+  def git_head
+    return unless git? && Utils.git_available?
+    cd do
+      Utils.popen_read("git", "rev-parse", "--verify", "-q", "HEAD").chuzzle
+    end
+  end
+
+  def git_short_head
+    return unless git? && Utils.git_available?
+    cd do
+      Utils.popen_read(
+        "git", "rev-parse", "--short=4", "--verify", "-q", "HEAD"
+      ).chuzzle
+    end
+  end
+
+  def git_last_commit
+    return unless git? && Utils.git_available?
+    cd do
+      Utils.popen_read("git", "show", "-s", "--format=%cr", "HEAD").chuzzle
+    end
+  end
+
+  def git_last_commit_date
+    return unless git? && Utils.git_available?
+    cd do
+      Utils.popen_read(
+        "git", "show", "-s", "--format=%cd", "--date=short", "HEAD"
+      ).chuzzle
+    end
+  end
+end
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index 02ff15e39..ab6bd9d5c 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -1,6 +1,7 @@
 require "extend/module"
 require "extend/fileutils"
 require "extend/pathname"
+require "extend/git_repository"
 require "extend/ARGV"
 require "extend/string"
 require "extend/enumerable"