Implement Resources

Closes Homebrew/homebrew#20212.

1 files changed, 57 insertions, 0 deletions

diff --git a/Library/Homebrew/resource.rb b/Library/Homebrew/resource.rb
new file mode 100644
index 000000000..1136af1c0
--- /dev/null
+++ b/Library/Homebrew/resource.rb
@@ -0,0 +1,57 @@
+# A Resource describes a tarball that a formula needs in addition
+# to the formula's own download.
+class Resource
+  include FileUtils
+
+  # The mktmp mixin expects a name property
+  # This is the resource name
+  attr_reader :name
+
+  # This is the associated formula name
+  attr_reader :owner_name
+
+  def initialize name, spec
+    @name = name
+    @spec = spec
+  end
+
+  # Formula name must be set after the DSL, as we have no access to the
+  # formula name before initialization of the formula
+  def set_owner owner
+    @owner = owner
+    @downloader = @spec.download_strategy.new("#{owner}--#{name}", @spec)
+  end
+
+  # Download the resource
+  # If a target is given, unpack there; else unpack to a temp folder
+  # If block is given, yield to that block
+  # A target or a block must be given, but not both
+  def stage(target=nil)
+    fetched = fetch
+    verify_download_integrity(fetched) if fetched.file?
+    mktemp do
+      @downloader.stage
+      if block_given?
+        yield self
+      else
+        target.install Dir['*']
+      end
+    end
+  end
+
+  def cached_download
+    @downloader.cached_location
+  end
+
+  # For brew-fetch and others.
+  def fetch
+    # Ensure the cache exists
+    HOMEBREW_CACHE.mkpath
+    @downloader.fetch
+    cached_download
+  end
+
+  def verify_download_integrity fn
+    @spec.verify_download_integrity(fn)
+  end
+end