1 files changed, 67 insertions, 0 deletions
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()
+}