Merge pull request #4563 from alebcay/extract

Add new extract dev command to retrieve old versions of formulae

Library/Homebrew/dev-cmd/extract.rb

@@ -0,0 +1,180 @@
+#:  * `extract` [`--force`] <formula> <tap> [`--version=`<version>]:
+#:    Looks through repository history to find the <version> of <formula> and
+#:    creates a copy in <tap>/Formula/<formula>@<version>.rb. If the tap is
+#:    not installed yet, attempts to install/clone the tap before continuing.
+#:
+#:    If `--force` is passed, the file at the destination will be overwritten
+#:    if it already exists. Otherwise, existing files will be preserved.
+#:
+#:    If an argument is passed through `--version`, <version> of <formula>
+#:    will be extracted and placed in the destination tap. Otherwise, the most
+#:    recent version that can be found will be used.
+
+require "cli_parser"
+require "utils/git"
+require "formulary"
+require "tap"
+
+def with_monkey_patch
+  BottleSpecification.class_eval do
+    if method_defined?(:method_missing)
+      alias_method :old_method_missing, :method_missing
+    end
+    define_method(:method_missing) { |*| }
+  end
+
+  Module.class_eval do
+    if method_defined?(:method_missing)
+      alias_method :old_method_missing, :method_missing
+    end
+    define_method(:method_missing) { |*| }
+  end
+
+  Resource.class_eval do
+    if method_defined?(:method_missing)
+      alias_method :old_method_missing, :method_missing
+    end
+    define_method(:method_missing) { |*| }
+  end
+
+  DependencyCollector.class_eval do
+    if method_defined?(:parse_symbol_spec)
+      alias_method :old_parse_symbol_spec, :parse_symbol_spec
+    end
+    define_method(:parse_symbol_spec) { |*| }
+  end
+
+  if defined?(DependencyCollector::Compat)
+    DependencyCollector::Compat.class_eval do
+      if method_defined?(:parse_string_spec)
+        alias_method :old_parse_string_spec, :parse_string_spec
+      end
+      define_method(:parse_string_spec) { |*| }
+    end
+  end
+
+  yield
+ensure
+  BottleSpecification.class_eval do
+    if method_defined?(:old_method_missing)
+      alias_method :method_missing, :old_method_missing
+      undef :old_method_missing
+    end
+  end
+
+  Module.class_eval do
+    if method_defined?(:old_method_missing)
+      alias_method :method_missing, :old_method_missing
+      undef :old_method_missing
+    end
+  end
+
+  Resource.class_eval do
+    if method_defined?(:old_method_missing)
+      alias_method :method_missing, :old_method_missing
+      undef :old_method_missing
+    end
+  end
+
+  DependencyCollector.class_eval do
+    if method_defined?(:old_parse_symbol_spec)
+      alias_method :parse_symbol_spec, :old_parse_symbol_spec
+      undef :old_parse_symbol_spec
+    end
+  end
+
+  if defined?(DependencyCollector::Compat)
+    DependencyCollector::Compat.class_eval do
+      if method_defined?(:old_parse_string_spec)
+        alias_method :parse_string_spec, :old_parse_string_spec
+        undef :old_parse_string_spec
+      end
+    end
+  end
+end
+
+module Homebrew
+  module_function
+
+  def extract
+    Homebrew::CLI::Parser.parse do
+      flag   "--version="
+      switch :debug
+      switch :force
+    end
+
+    # Expect exactly two named arguments: formula and tap
+    raise UsageError if ARGV.named.length != 2
+
+    destination_tap = Tap.fetch(ARGV.named[1])
+    odie "Cannot extract formula to homebrew/core!" if destination_tap.core_tap?
+    destination_tap.install unless destination_tap.installed?
+
+    name = ARGV.named.first.downcase
+    repo = CoreTap.instance.path
+    # Formulae can technically live in "<repo>/<formula>.rb" or
+    # "<repo>/Formula/<formula>.rb", but explicitly use the latter for now
+    # since that is now core tap is structured.
+    file = repo/"Formula/#{name}.rb"
+
+    if args.version
+      ohai "Searching repository history"
+      version = args.version
+      rev = "HEAD"
+      test_formula = nil
+      loop do
+        loop do
+          rev = Git.last_revision_commit_of_file(repo, file, before_commit: "#{rev}~1")
+          break if rev.empty?
+          break unless Git.last_revision_of_file(repo, file, before_commit: rev).empty?
+          ohai "Skipping revision #{rev} - file is empty at this revision" if ARGV.debug?
+        end
+        test_formula = formula_at_revision(repo, name, file, rev)
+        break if test_formula.nil? || test_formula.version == version
+        ohai "Trying #{test_formula.version} from revision #{rev} against desired #{version}" if ARGV.debug?
+      end
+      odie "Could not find #{name}! The formula or version may not have existed." if test_formula.nil?
+      result = Git.last_revision_of_file(repo, file, before_commit: rev)
+    elsif File.exist?(file)
+      rev = "HEAD"
+      version = Formulary.factory(file).version
+      result = File.read(file)
+    else
+      ohai "Searching repository history"
+      rev = Git.last_revision_commit_of_file(repo, file)
+      version = formula_at_revision(repo, name, file, rev).version
+      odie "Could not find #{name}! The formula or version may not have existed." if rev.empty?
+      result = Git.last_revision_of_file(repo, file)
+    end
+
+    # The class name has to be renamed to match the new filename,
+    # e.g. Foo version 1.2.3 becomes FooAT123 and resides in Foo@1.2.3.rb.
+    class_name = name.capitalize
+    versioned_name = Formulary.class_s("#{class_name}@#{version}")
+    result.gsub!("class #{class_name} < Formula", "class #{versioned_name} < Formula")
+
+    path = destination_tap.path/"Formula/#{name}@#{version}.rb"
+    if path.exist?
+      unless ARGV.force?
+        odie <<~EOS
+          Destination formula already exists: #{path}
+          To overwrite it and continue anyways, run:
+            `brew extract #{name} --version=#{version} --tap=#{destination_tap.name} --force`
+        EOS
+      end
+      ohai "Overwriting existing formula at #{path}" if ARGV.debug?
+      path.delete
+    end
+    ohai "Writing formula for #{name} from revision #{rev} to #{path}"
+    path.write result
+  end
+
+  # @private
+  def formula_at_revision(repo, name, file, rev)
+    return if rev.empty?
+    contents = Git.last_revision_of_file(repo, file, before_commit: rev)
+    contents.gsub!("@url=", "url ")
+    contents.gsub!("require 'brewkit'", "require 'formula'")
+    with_monkey_patch { Formulary.from_contents(name, file, contents) }
+  end
+end

Library/Homebrew/test/dev-cmd/extract_spec.rb

@@ -0,0 +1,32 @@
+describe "brew extract", :integration_test do
+  it "retrieves the specified version of formula, defaulting to most recent" do
+    path = Tap::TAP_DIRECTORY/"homebrew/homebrew-foo"
+    (path/"Formula").mkpath
+    target = Tap.from_path(path)
+    core_tap = CoreTap.new
+    core_tap.path.cd do
+      system "git", "init"
+      formula_file = setup_test_formula "testball"
+      system "git", "add", "--all"
+      system "git", "commit", "-m", "testball 0.1"
+      contents = File.read(formula_file)
+      contents.gsub!("testball-0.1", "testball-0.2")
+      File.write(formula_file, contents)
+      system "git", "add", "--all"
+      system "git", "commit", "-m", "testball 0.2"
+    end
+    expect { brew "extract", "testball", target.name }
+      .to be_a_success
+
+    expect(path/"Formula/testball@0.2.rb").to exist
+
+    expect(Formulary.factory(path/"Formula/testball@0.2.rb").version).to be == "0.2"
+
+    expect { brew "extract", "testball", target.name, "--version=0.1" }
+      .to be_a_success
+
+    expect(path/"Formula/testball@0.1.rb").to exist
+
+    expect(Formulary.factory(path/"Formula/testball@0.1.rb").version).to be == "0.1"
+  end
+end

docs/Manpage.md

@@ -790,6 +790,18 @@ With `--verbose` or `-v`, many commands print extra debugging information. Note
   * `edit` `formula`:
     Open `formula` in the editor.
 
+  * `extract` [`--force`] `formula` `tap` [`--version=``version`]:
+    Looks through repository history to find the `version` of `formula` and
+    creates a copy in `tap`/Formula/`formula`@`version`.rb. If the tap is
+    not installed yet, attempts to install/clone the tap before continuing.
+
+    If `--force` is passed, the file at the destination will be overwritten
+    if it already exists. Otherwise, existing files will be preserved.
+
+    If an argument is passed through `--version`, `version` of `formula`
+    will be extracted and placed in the destination tap. Otherwise, the most
+    recent version that can be found will be used.
+
   * `formula` `formula`:
     Display the path where `formula` is located.
 

manpages/brew.1

@@ -727,6 +727,16 @@ Open all of Homebrew for editing\.
 Open \fIformula\fR in the editor\.
 .
 .TP
+\fBextract\fR [\fB\-\-force\fR] \fIformula\fR \fItap\fR [\fB\-\-version=\fR\fIversion\fR]
+Looks through repository history to find the \fIversion\fR of \fIformula\fR and creates a copy in \fItap\fR/Formula/\fIformula\fR@\fIversion\fR\.rb\. If the tap is not installed yet, attempts to install/clone the tap before continuing\.
+.
+.IP
+If \fB\-\-force\fR is passed, the file at the destination will be overwritten if it already exists\. Otherwise, existing files will be preserved\.
+.
+.IP
+If an argument is passed through \fB\-\-version\fR, \fIversion\fR of \fIformula\fR will be extracted and placed in the destination tap\. Otherwise, the most recent version that can be found will be used\.
+.
+.TP
 \fBformula\fR \fIformula\fR
 Display the path where \fIformula\fR is located\.
 .