versions: determine version from a Formula instance

Rather than regex the output of `git show <rev>:<path>`, we write the
output of `git cat-file blog <rev>:<path>` to a temporary file, and then
operate on it just as we would a normal formula.

I haven't observed any speed difference. `git cat-file blob` is faster
than `git show`, but the "slow part" is still the git-rev-list
invocation. But really it's pretty fast overall.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

1 files changed, 38 insertions, 46 deletions

diff --git a/Library/Homebrew/cmd/versions.rb b/Library/Homebrew/cmd/versions.rb
index 5283d9cb3..bd234d843 100644
--- a/Library/Homebrew/cmd/versions.rb
+++ b/Library/Homebrew/cmd/versions.rb
@@ -1,26 +1,11 @@
 require 'formula'
 
 module Homebrew extend self
-
-  module Versions
-    # yields version, sha for all versions in the git history
-    def self.old_versions f
-      yielded = []
-      f.rev_list.each do |sha|
-        version = f.version_for_sha sha
-        unless yielded.include? version or version.nil?
-          yield version, sha
-          yielded << version
-        end
-      end
-    end
-  end
-
   def versions
     raise "Please `brew install git` first" unless system "/usr/bin/which -s git"
 
     ARGV.formulae.all? do |f|
-      old_versions = Versions.old_versions f do |version, sha|
+      f.versions do |version, sha|
         print Tty.white
         print "#{version.ljust(8)} "
         print Tty.reset
@@ -28,49 +13,56 @@ module Homebrew extend self
       end
     end
   end
-
 end
 
 
 class Formula
-  def rev_list
-    Dir.chdir HOMEBREW_REPOSITORY do
-      `git rev-list --abbrev-commit HEAD Library/Formula/#{name}.rb`.split
+  def versions
+    versions = []
+    rev_list.each do |sha|
+      version = version_for_sha sha
+      unless versions.include? version or version.nil?
+        yield version, sha if block_given?
+        versions << version
+      end
     end
+    return versions
   end
 
-  def sha_for_version version
-    revlist.find{ |sha| version == version_for(sha) }
+  def pretty_relative_path
+    if Pathname.pwd == HOMEBREW_REPOSITORY
+      "Library/Formula/#{name}.rb"
+    else
+      "#{HOMEBREW_REPOSITORY}/Library/Formula/#{name}.rb"
+    end
   end
 
-  def version_for_sha sha
-    # TODO really we should open a new ruby instance and parse the formula
-    # class and then get the version but this would be too slow (?)
-
-    code = Dir.chdir(HOMEBREW_REPOSITORY) do
-      `git show #{sha}:Library/Formula/#{name}.rb`
+  private
+    def rev_list
+      HOMEBREW_REPOSITORY.cd do
+        `git rev-list --abbrev-commit HEAD -- Library/Formula/#{name}.rb`.split
+      end
     end
 
-    version = code.match(/class #{Formula.class_s name} < ?Formula.*?(?:version\s|@version\s*=)\s*(?:'|")(.+?)(?:'|").*?end\s/m)
-    return version[1] unless version.nil?
-
-    url = code.match(/class #{Formula.class_s name} < ?Formula.*?(?:url\s|@url\s*=)\s*(?:'|")(.+?)(?:'|").*?end\s/m)
-    unless url.nil?
-      version = Pathname.new(url[1]).version
-      return version unless version.to_s.empty?
+    def text_from_sha sha
+      HOMEBREW_REPOSITORY.cd do
+        `git cat-file blob #{sha}:Library/Formula/#{name}.rb`
+      end
     end
 
-    head = code.match(/class #{Formula.class_s name} < ?Formula.*?head\s'(.*?)'.*?end\s\s/m)
-    return 'HEAD' unless head.nil?
-
-    opoo "Version of #{name} could not be determined for #{sha}."
-  end
+    def sha_for_version version
+      rev_list.find{ |sha| version == version_for_sha(sha) }
+    end
 
-  def pretty_relative_path
-    if Pathname.pwd == HOMEBREW_REPOSITORY
-      "Library/Formula/#{name}.rb"
-    else
-      "#{HOMEBREW_REPOSITORY}/Library/Formula/#{name}.rb"
+    def version_for_sha sha
+      begin
+        version = mktemp do
+          path = Pathname.new(Pathname.pwd+"#{name}.rb")
+          path.write text_from_sha(sha)
+          Formula.factory(path).version
+        end
+      rescue
+        opoo "Version of #{name} could not be determined for #{sha}."
+      end
     end
-  end
 end