Add support for --apply

This option would be useful to apply pending branches to merge on top of
another (non-integration) branch. Mostly for comparison purposes.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>

doc/git-reintegrate.txt

@@ -11,7 +11,7 @@ SYNOPSIS
 'git reintegrate' --create <name> [<base>]
 'git-reintegrate' --generate <name> [<base>]
 'git-reintegrate' --add=<name>
-'git-reintegrate' (--edit | --rebuild | --cat | --status) [<name>]
+'git-reintegrate' (--edit | --rebuild | --apply | --cat | --status) [<name>]
 'git reintegrate' (--continue | --abort)
 'git-reintegrate' --list
 
@@ -78,6 +78,11 @@ If no base is specified, 'master' is assumed.
 	Delete an integration branch. It doesn't delete the branch itself, only
 	the integration information.
 
+--apply::
+	Applies the instruction sheet of the integration branch on top of the
+	current branch. If a branch to merge is already completely merged in
+	the current branch, it's skipped.
+
 If `--continue` or `--abort` are specified then no other options may be given.
 
 CONFIGURATION

git-reintegrate

@@ -126,11 +126,17 @@ end
 class Branch
 
   attr_reader :name, :ref, :int
+  attr_reader :into_name, :into_ref
 
   def initialize(name)
     @name = name
   end
 
+  def into_name=(name)
+    @into_name = name
+    @into_ref = %x[git rev-parse --symbolic-full-name "refs/heads/#{name}"].chomp
+  end
+
   def get
     if @name
       @ref = %x[git rev-parse --symbolic-full-name "refs/heads/#{@name}"].chomp
@@ -291,7 +297,7 @@ class Integration
     self.new(obj).run
   end
 
-  def self.start(branch, inst)
+  def self.start(branch, into_name, inst)
     require_clean_work_tree('integrate', "Please commit or stash them.")
 
     orig_head = %x[git rev-parse --quiet --verify "#{branch}^{commit}"].chomp
@@ -306,6 +312,9 @@ class Integration
     commit = %x[git rev-parse --quiet --verify #{branch}].chomp
     File.write($start_file, commit)
 
+    $branch.into_name = into_name
+    File.write($into_file, into_name)
+
     File.write($insns, inst)
     self.run(inst)
   end
@@ -336,11 +345,15 @@ class Integration
   end
 
   def finish
-    system(*%w[git update-ref], $branch.ref, 'HEAD', File.read($start_file))
-    system(*%w[git symbolic-ref], 'HEAD', $branch.ref)
+    system(*%w[git update-ref], $branch.into_ref, 'HEAD', File.read($start_file))
+    system(*%w[git symbolic-ref], 'HEAD', $branch.into_ref)
     FileUtils.rm_rf($state_dir)
     system(*%w[git gc --auto])
-    puts "Successfully re-integrated #{$branch.name}."
+    if $branch.name == $branch.into_name
+      puts "Successfully re-integrated #{$branch.name}."
+    else
+      puts "Successfully applied #{$branch.name} into #{$branch.into_name}."
+    end
   end
 
   def stop(msg = nil)
@@ -416,7 +429,7 @@ def deindent(msg)
 end
 
 def cmd_merge(message, branch_to_merge, *args)
-  merge_msg = "Merge branch '#{branch_to_merge}' into #{$branch.name}\n"
+  merge_msg = "Merge branch '#{branch_to_merge}' into #{$branch.into_name}\n"
   merge_msg += "\n#{deindent(message)}\n" unless message.empty?
 
   merge_opts = args
@@ -497,6 +510,7 @@ def get_head_file
   branch_name = File.read($head_file).gsub(%r{^refs/heads/}, '')
   branch = Branch.new(branch_name)
   branch.get
+  branch.into_name = File.read($into_file)
   return branch
 end
 
@@ -525,11 +539,29 @@ end
 def do_abort
   $branch = get_head_file
 
-  system(*%w[git symbolic-ref HEAD], $branch.ref) &&
-    system(*%w[git reset --hard], $branch.ref) &&
+  system(*%w[git symbolic-ref HEAD], $branch.into_ref) &&
+    system(*%w[git reset --hard], $branch.into_ref) &&
     FileUtils.rm_rf($state_dir)
 end
 
+def do_apply
+  head = %x[git rev-parse --symbolic --abbrev-ref HEAD].chomp
+
+  inst = $branch.read_instructions
+  die "Failed to read instruction list for branch #{$branch.name}" unless $?.success?
+
+  inst = inst.lines.reject do |line|
+    next true if line =~ /^base /
+    if line =~ /^merge (.*)$/
+      system(*%W[git merge-base --is-ancestor #{$1} HEAD])
+      next true if $?.success?
+    end
+    false
+  end.join
+
+  Integration.start(head, head, inst)
+end
+
 def status_merge(branch_to_merge = nil)
   if not branch_to_merge
     $stderr.puts "no branch specified with 'merge' command"
@@ -646,6 +678,10 @@ opts.on('d', 'delete', 'delete an integration branch') do |v|
   $delete = true
 end
 
+opts.on(nil, 'apply', 'apply an integration branch on the current branch') do |v|
+  $apply = true
+end
+
 %x[git config --bool --get integration.autocontinue].chomp == "true" &&
 $autocontinue = true
 
@@ -658,6 +694,7 @@ $start_file = "#{$state_dir}/start-point"
 $head_file = "#{$state_dir}/head-name"
 $merged_file = "#{$state_dir}/merged"
 $insns = "#{$state_dir}/instructions"
+$into_file = "#{$state_dir}/into"
 
 case $actions.first
 when :continue
@@ -713,6 +750,10 @@ if $rebuild
   do_rebuild
 end
 
+if $apply
+  do_apply
+end
+
 if $status
   do_status
 end

test/apply.t

@@ -0,0 +1,68 @@
+#!/bin/sh
+
+#
+# Copyright (C) 2014 Felipe Contreras
+#
+# This file may be used under the terms of the GNU GPL version 2.
+#
+
+test_description='Test git reintegrage apply option'
+
+. ./test-lib.sh
+
+commit_file() {
+	local filename="$1"
+	echo "$2" > $filename &&
+	git add -f $filename &&
+	git commit -q -m "commit $filename"
+}
+
+test_expect_success 'setup branches' '
+	git init -q &&
+	commit_file base base &&
+
+	git checkout -b feature-1 master &&
+	commit_file feature-1 feature-1 &&
+	git checkout -b feature-2 master &&
+	commit_file feature-2 feature-2 &&
+
+	git checkout -b next master &&
+	git merge --no-ff feature-1 &&
+	git merge --no-ff feature-2
+'
+
+test_expect_success 'generate integration' '
+	git reintegrate --create integration &&
+	git reintegrate --add=feature-1 --add=feature-2 &&
+	git reintegrate --rebuild &&
+	> expected &&
+	git diff next integration > actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'update integration' '
+	git checkout feature-1 &&
+	commit_file feature-1-fix feature-1-fix &&
+	git reintegrate --rebuild integration &&
+	git diff feature-1^..feature-1 > expected &&
+	git diff next integration > actual &&
+	test_cmp expected actual
+'
+
+cat > expected <<EOF
+Merge branch 'feature-1' into next
+commit feature-1-fix
+EOF
+
+test_expect_success 'apply pending' '
+	git checkout next &&
+	git branch old &&
+	git reintegrate --apply integration &&
+	git log --format=%s old..next > actual &&
+	test_cmp expected actual &&
+	> expected &&
+	git diff next integration > actual &&
+	test_cmp expected actual
+'
+
+test_done