Merge branch 'tr/previous-branch'

* tr/previous-branch:
  t1505: remove debugging cruft
  Simplify parsing branch switching events in reflog
  Introduce for_each_recent_reflog_ent().
  interpret_nth_last_branch(): plug small memleak
  Fix reflog parsing for a malformed branch switching entry
  Fix parsing of @{-1}@{1}
  interpret_nth_last_branch(): avoid traversing the reflog twice
  checkout: implement "-" abbreviation, add docs and tests
  sha1_name: support @{-N} syntax in get_sha1()
  sha1_name: tweak @{-N} lookup
  checkout: implement "@{-N}" shortcut name for N-th last branch

Conflicts:
	sha1_name.c

2 files changed, 163 insertions, 0 deletions

diff --git a/t/t1505-rev-parse-last.sh b/t/t1505-rev-parse-last.sh
new file mode 100755
index 0000000000..d709ecf8df
--- /dev/null
+++ b/t/t1505-rev-parse-last.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+test_description='test @{-N} syntax'
+
+. ./test-lib.sh
+
+
+make_commit () {
+	echo "$1" > "$1" &&
+	git add "$1" &&
+	git commit -m "$1"
+}
+
+
+test_expect_success 'setup' '
+
+	make_commit 1 &&
+	git branch side &&
+	make_commit 2 &&
+	make_commit 3 &&
+	git checkout side &&
+	make_commit 4 &&
+	git merge master &&
+	git checkout master
+
+'
+
+# 1 -- 2 -- 3 master
+#  \         \
+#   \         \
+#    --- 4 --- 5 side
+#
+# and 'side' should be the last branch
+
+test_rev_equivalent () {
+
+	git rev-parse "$1" > expect &&
+	git rev-parse "$2" > output &&
+	test_cmp expect output
+
+}
+
+test_expect_success '@{-1} works' '
+	test_rev_equivalent side @{-1}
+'
+
+test_expect_success '@{-1}~2 works' '
+	test_rev_equivalent side~2 @{-1}~2
+'
+
+test_expect_success '@{-1}^2 works' '
+	test_rev_equivalent side^2 @{-1}^2
+'
+
+test_expect_success '@{-1}@{1} works' '
+	test_rev_equivalent side@{1} @{-1}@{1}
+'
+
+test_expect_success '@{-2} works' '
+	test_rev_equivalent master @{-2}
+'
+
+test_expect_success '@{-3} fails' '
+	test_must_fail git rev-parse @{-3}
+'
+
+test_done
+
+
diff --git a/t/t2012-checkout-last.sh b/t/t2012-checkout-last.sh
new file mode 100755
index 0000000000..87b30a268c
--- /dev/null
+++ b/t/t2012-checkout-last.sh
@@ -0,0 +1,94 @@
+#!/bin/sh
+
+test_description='checkout can switch to last branch'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	echo hello >world &&
+	git add world &&
+	git commit -m initial &&
+	git branch other &&
+	echo "hello again" >>world &&
+	git add world &&
+	git commit -m second
+'
+
+test_expect_success '"checkout -" does not work initially' '
+	test_must_fail git checkout -
+'
+
+test_expect_success 'first branch switch' '
+	git checkout other
+'
+
+test_expect_success '"checkout -" switches back' '
+	git checkout - &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/master"
+'
+
+test_expect_success '"checkout -" switches forth' '
+	git checkout - &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/other"
+'
+
+test_expect_success 'detach HEAD' '
+	git checkout $(git rev-parse HEAD)
+'
+
+test_expect_success '"checkout -" attaches again' '
+	git checkout - &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/other"
+'
+
+test_expect_success '"checkout -" detaches again' '
+	git checkout - &&
+	test "z$(git rev-parse HEAD)" = "z$(git rev-parse other)" &&
+	test_must_fail git symbolic-ref HEAD
+'
+
+test_expect_success 'more switches' '
+	for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
+	do
+		git checkout -b branch$i
+	done
+'
+
+more_switches () {
+	for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
+	do
+		git checkout branch$i
+	done
+}
+
+test_expect_success 'switch to the last' '
+	more_switches &&
+	git checkout @{-1} &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch2"
+'
+
+test_expect_success 'switch to second from the last' '
+	more_switches &&
+	git checkout @{-2} &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch3"
+'
+
+test_expect_success 'switch to third from the last' '
+	more_switches &&
+	git checkout @{-3} &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch4"
+'
+
+test_expect_success 'switch to fourth from the last' '
+	more_switches &&
+	git checkout @{-4} &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch5"
+'
+
+test_expect_success 'switch to twelfth from the last' '
+	more_switches &&
+	git checkout @{-12} &&
+	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/branch13"
+'
+
+test_done