WalkCommitHistory adn Commit.History

5 files changed, 144 insertions, 0 deletions

diff --git a/commit.go b/commit.go
index 4a4a202..4a4fe25 100644
--- a/commit.go
+++ b/commit.go
@@ -125,6 +125,18 @@ func (c *Commit) Decode(o core.Object) (err error) {
 	}
 }
 
+// History return a slice with the previous commits in the history of this commit
+func (c *Commit) History() ([]*Commit, error) {
+	var commits []*Commit
+	err := WalkCommitHistory(c, func(commit *Commit) error {
+		commits = append(commits, commit)
+		return nil
+	})
+
+	ReverseSortCommits(commits)
+	return commits, err
+}
+
 func (c *Commit) String() string {
 	return fmt.Sprintf(
 		"%s %s\nAuthor: %s\nDate:   %s\n",
@@ -193,3 +205,9 @@ func SortCommits(l []*Commit) {
 	s := &commitSorterer{l}
 	sort.Sort(s)
 }
+
+// ReverseSortCommits sort a commit list by commit date, from newer to older.
+func ReverseSortCommits(l []*Commit) {
+	s := &commitSorterer{l}
+	sort.Sort(sort.Reverse(s))
+}
diff --git a/commit_test.go b/commit_test.go
index 82133da..9a05cd8 100644
--- a/commit_test.go
+++ b/commit_test.go
@@ -72,6 +72,14 @@ func (s *SuiteCommit) TestNumParents(c *C) {
 	c.Assert(s.Commit.NumParents(), Equals, 2)
 }
 
+func (s *SuiteCommit) TestHistory(c *C) {
+	commits, err := s.Commit.History()
+	c.Assert(err, IsNil)
+	c.Assert(commits, HasLen, 5)
+	c.Assert(commits[0].Hash.String(), Equals, s.Commit.Hash.String())
+	c.Assert(commits[len(commits)-1].Hash.String(), Equals, "b029517f6300c2da0f4b651b8642506cd6aaf45d")
+}
+
 func (s *SuiteCommit) TestString(c *C) {
 	c.Assert(s.Commit.String(), Equals, ""+
 		"commit 1669dce138d9b841a518c64b10914d88f5e488ea\n"+
diff --git a/commit_walker.go b/commit_walker.go
new file mode 100644
index 0000000..e595a84
--- /dev/null
+++ b/commit_walker.go
@@ -0,0 +1,67 @@
+package git
+
+import (
+	"io"
+
+	"gopkg.in/src-d/go-git.v4/core"
+)
+
+type commitWalker struct {
+	seen  map[core.Hash]bool
+	stack []*CommitIter
+	start *Commit
+	cb    func(*Commit) error
+}
+
+// WalkCommitHistory walks the commit history
+func WalkCommitHistory(c *Commit, cb func(*Commit) error) error {
+	w := &commitWalker{
+		seen:  make(map[core.Hash]bool),
+		stack: make([]*CommitIter, 0),
+		start: c,
+		cb:    cb,
+	}
+
+	return w.walk()
+}
+
+func (w *commitWalker) walk() error {
+	var commit *Commit
+
+	if w.start != nil {
+		commit = w.start
+		w.start = nil
+	} else {
+		current := len(w.stack) - 1
+		if current < 0 {
+			return nil
+		}
+
+		var err error
+		commit, err = w.stack[current].Next()
+		if err == io.EOF {
+			w.stack = w.stack[:current]
+			return w.walk()
+		}
+
+		if err != nil {
+			return err
+		}
+	}
+
+	// check and update seen
+	if w.seen[commit.Hash] {
+		return w.walk()
+	}
+
+	w.seen[commit.Hash] = true
+	if commit.NumParents() > 0 {
+		w.stack = append(w.stack, commit.Parents())
+	}
+
+	if err := w.cb(commit); err != nil {
+		return err
+	}
+
+	return w.walk()
+}
diff --git a/commit_walker_test.go b/commit_walker_test.go
new file mode 100644
index 0000000..cf239bc
--- /dev/null
+++ b/commit_walker_test.go
@@ -0,0 +1,38 @@
+package git
+
+import . "gopkg.in/check.v1"
+
+type CommitWalkerSuite struct {
+	BaseSuite
+}
+
+var _ = Suite(&CommitWalkerSuite{})
+
+func (s *CommitWalkerSuite) TestWalkerNext(c *C) {
+	r, err := s.Repository.Head()
+	c.Assert(err, IsNil)
+
+	commit, err := s.Repository.Commit(r.Hash())
+	c.Assert(err, IsNil)
+
+	var commits []*Commit
+
+	WalkCommitHistory(commit, func(c *Commit) error {
+		commits = append(commits, c)
+		return nil
+	})
+
+	SortCommits(commits)
+	c.Assert(commits, HasLen, 8)
+
+	expected := []string{
+		"b029517f6300c2da0f4b651b8642506cd6aaf45d", "b8e471f58bcbca63b07bda20e428190409c2db47",
+		"35e85108805c84807bc66a02d91535e1e24b38b9", "a5b8b09e2f8fcb0bb99d3ccb0958157b40890d69",
+		"1669dce138d9b841a518c64b10914d88f5e488ea", "af2d6a6954d532f8ffb47615169c8fdf9d383a1a",
+		"918c48b83bd081e863dbe1b80f8998f058cd8294", "6ecf0ef2c2dffb796033e5a02219af86ec6584e5",
+	}
+
+	for i, commit := range commits {
+		c.Assert(commit.Hash.String(), Equals, expected[i])
+	}
+}
diff --git a/examples/basic/main.go b/examples/basic/main.go
index 85d6a57..4cdfa4b 100644
--- a/examples/basic/main.go
+++ b/examples/basic/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/fatih/color"
 
@@ -46,4 +47,16 @@ func main() {
 		fmt.Printf("100644 blob %s    %s\n", f.Hash, f.Name)
 		return nil
 	})
+
+	// List the history of the repository
+	// > git log --oneline
+	color.Blue("git log --oneline")
+
+	commits, _ := commit.History()
+	for _, c := range commits {
+		hash := c.Hash.String()
+		line := strings.Split(c.Message, "\n")
+		fmt.Println(hash[:7], line[0])
+	}
+
 }