Support partial hashes in Repository.ResolveRevision.

Like `git rev-parse <prefix>`, this enumerates the hashes of objects
with the given prefix and adds them to the list of candidates for
resolution.

This has an exhaustive slow path, which requires enumerating all objects
and filtering each one, but also a couple of fast paths for common
cases. There's room for future work to make this faster; TODOs have been
left for that.

Fixes #135.

1 files changed, 35 insertions, 0 deletions

diff --git a/storage/filesystem/dotgit/dotgit_test.go b/storage/filesystem/dotgit/dotgit_test.go
index 0a72aa6..237605f 100644
--- a/storage/filesystem/dotgit/dotgit_test.go
+++ b/storage/filesystem/dotgit/dotgit_test.go
@@ -2,6 +2,7 @@ package dotgit
 
 import (
 	"bufio"
+	"encoding/hex"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -591,6 +592,7 @@ func (s *SuiteDotGit) TestObjects(c *C) {
 	dir := New(fs)
 
 	testObjects(c, fs, dir)
+	testObjectsWithPrefix(c, fs, dir)
 }
 
 func (s *SuiteDotGit) TestObjectsExclusive(c *C) {
@@ -598,6 +600,7 @@ func (s *SuiteDotGit) TestObjectsExclusive(c *C) {
 	dir := NewWithOptions(fs, Options{ExclusiveAccess: true})
 
 	testObjects(c, fs, dir)
+	testObjectsWithPrefix(c, fs, dir)
 }
 
 func testObjects(c *C, fs billy.Filesystem, dir *DotGit) {
@@ -609,6 +612,20 @@ func testObjects(c *C, fs billy.Filesystem, dir *DotGit) {
 	c.Assert(hashes[2].String(), Equals, "03db8e1fbe133a480f2867aac478fd866686d69e")
 }
 
+func testObjectsWithPrefix(c *C, fs billy.Filesystem, dir *DotGit) {
+	prefix, _ := hex.DecodeString("01d5")
+	hashes, err := dir.ObjectsWithPrefix(prefix)
+	c.Assert(err, IsNil)
+	c.Assert(hashes, HasLen, 1)
+	c.Assert(hashes[0].String(), Equals, "01d5fa556c33743006de7e76e67a2dfcd994ca04")
+
+	// Empty prefix should yield all objects.
+	// (subset of testObjects)
+	hashes, err = dir.ObjectsWithPrefix(nil)
+	c.Assert(err, IsNil)
+	c.Assert(hashes, HasLen, 187)
+}
+
 func (s *SuiteDotGit) TestObjectsNoFolder(c *C) {
 	tmp, err := ioutil.TempDir("", "dot-git")
 	c.Assert(err, IsNil)
@@ -835,3 +852,21 @@ type norwfs struct {
 func (f *norwfs) Capabilities() billy.Capability {
 	return billy.Capabilities(f.Filesystem) &^ billy.ReadAndWriteCapability
 }
+
+func (s *SuiteDotGit) TestIncBytes(c *C) {
+	tests := []struct {
+		in       []byte
+		out      []byte
+		overflow bool
+	}{
+		{[]byte{0}, []byte{1}, false},
+		{[]byte{0xff}, []byte{0}, true},
+		{[]byte{7, 0xff}, []byte{8, 0}, false},
+		{[]byte{0xff, 0xff}, []byte{0, 0}, true},
+	}
+	for _, test := range tests {
+		out, overflow := incBytes(test.in)
+		c.Assert(out, DeepEquals, test.out)
+		c.Assert(overflow, Equals, test.overflow)
+	}
+}