rev-parse: add --prefix option

This makes 'git rev-parse' behave as if it were invoked from the
specified subdirectory of a repository, with the difference that any
file paths which it prints are prefixed with the full path from the top
of the working tree.

This is useful for shell scripts where we may want to cd to the top of
the working tree but need to handle relative paths given by the user on
the command line.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/t/t1513-rev-parse-prefix.sh b/t/t1513-rev-parse-prefix.sh
new file mode 100755
index 0000000000..87ec3ae714
--- /dev/null
+++ b/t/t1513-rev-parse-prefix.sh
@@ -0,0 +1,96 @@
+#!/bin/sh
+
+test_description='Tests for rev-parse --prefix'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	mkdir -p sub1/sub2 &&
+	echo top >top &&
+	echo file1 >sub1/file1 &&
+	echo file2 >sub1/sub2/file2 &&
+	git add top sub1/file1 sub1/sub2/file2 &&
+	git commit -m commit
+'
+
+test_expect_success 'empty prefix -- file' '
+	git rev-parse --prefix "" -- top sub1/file1 >actual &&
+	cat <<-\EOF >expected &&
+	--
+	top
+	sub1/file1
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'valid prefix -- file' '
+	git rev-parse --prefix sub1/ -- file1 sub2/file2 >actual &&
+	cat <<-\EOF >expected &&
+	--
+	sub1/file1
+	sub1/sub2/file2
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'valid prefix -- ../file' '
+	git rev-parse --prefix sub1/ -- ../top sub2/file2 >actual &&
+	cat <<-\EOF >expected &&
+	--
+	sub1/../top
+	sub1/sub2/file2
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'empty prefix HEAD:./path' '
+	git rev-parse --prefix "" HEAD:./top >actual &&
+	git rev-parse HEAD:top >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'valid prefix HEAD:./path' '
+	git rev-parse --prefix sub1/ HEAD:./file1 >actual &&
+	git rev-parse HEAD:sub1/file1 >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'valid prefix HEAD:../path' '
+	git rev-parse --prefix sub1/ HEAD:../top >actual &&
+	git rev-parse HEAD:top >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'prefix ignored with HEAD:top' '
+	git rev-parse --prefix sub1/ HEAD:top >actual &&
+	git rev-parse HEAD:top >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'disambiguate path with valid prefix' '
+	git rev-parse --prefix sub1/ file1 >actual &&
+	cat <<-\EOF >expected &&
+	sub1/file1
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'file and refs with prefix' '
+	git rev-parse --prefix sub1/ master file1 >actual &&
+	cat <<-EOF >expected &&
+	$(git rev-parse master)
+	sub1/file1
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'two-levels deep' '
+	git rev-parse --prefix sub1/sub2/ -- file2 >actual &&
+	cat <<-\EOF >expected &&
+	--
+	sub1/sub2/file2
+	EOF
+	test_cmp expected actual
+'
+
+test_done