1 files changed, 82 insertions, 0 deletions
diff --git a/formats/packfile/packfile.go b/formats/packfile/packfile.go
new file mode 100644
index 0000000..d70f396
--- /dev/null
+++ b/formats/packfile/packfile.go
@@ -0,0 +1,82 @@
+package packfile
+
+import "fmt"
+
+type Packfile struct {
+	Version     uint32
+	Size        int64
+	ObjectCount int
+	Checksum    []byte
+	Commits     map[Hash]*Commit
+	Trees       map[Hash]*Tree
+	Blobs       map[Hash]*Blob
+}
+
+func NewPackfile() *Packfile {
+	return &Packfile{
+		Commits: make(map[Hash]*Commit, 0),
+		Trees:   make(map[Hash]*Tree, 0),
+		Blobs:   make(map[Hash]*Blob, 0),
+	}
+}
+
+type BlobEntry struct {
+	path string
+	*Blob
+}
+
+type SubtreeEntry struct {
+	path string
+	*Tree
+	TreeCh
+}
+
+type treeEntry interface {
+	isTreeEntry()
+	Path() string
+}
+
+func (b BlobEntry) isTreeEntry()    {}
+func (b BlobEntry) Path() string    { return b.path }
+func (b SubtreeEntry) isTreeEntry() {}
+func (b SubtreeEntry) Path() string { return b.path }
+
+type TreeCh <-chan treeEntry
+
+func (p *Packfile) WalkCommit(commitHash Hash) (TreeCh, error) {
+	commit, ok := p.Commits[commitHash]
+	if !ok {
+		return nil, fmt.Errorf("Unable to find %q commit", commitHash)
+	}
+
+	return p.WalkTree(p.Trees[commit.Tree]), nil
+}
+
+func (p *Packfile) WalkTree(tree *Tree) TreeCh {
+	return p.walkTree(tree, "")
+}
+
+func (p *Packfile) walkTree(tree *Tree, pathPrefix string) TreeCh {
+	ch := make(chan treeEntry)
+
+	if tree == nil {
+		close(ch)
+		return ch
+	}
+
+	go func() {
+		defer func() {
+			close(ch)
+		}()
+		for _, e := range tree.Entries {
+			path := pathPrefix + e.Name
+			if blob, ok := p.Blobs[e.Hash]; ok {
+				ch <- BlobEntry{path, blob}
+			} else if subtree, ok := p.Trees[e.Hash]; ok {
+				ch <- SubtreeEntry{path, subtree, p.walkTree(subtree, path+"/")}
+			}
+		}
+	}()
+
+	return ch
+}