Merge pull request #13 from libgit2/polymorphism-take-2

My take on polymorphism

1 files changed, 84 insertions, 0 deletions

diff --git a/object.go b/object.go
new file mode 100644
index 0000000..c6cd8a8
--- /dev/null
+++ b/object.go
@@ -0,0 +1,84 @@
+package git
+
+/*
+#cgo pkg-config: libgit2
+#include <git2.h>
+#include <git2/errors.h>
+*/
+import "C"
+import "runtime"
+
+type ObjectType int
+
+var (
+	OBJ_ANY ObjectType = C.GIT_OBJ_ANY
+	OBJ_BAD ObjectType = C.GIT_OBJ_BAD
+	OBJ_COMMIT ObjectType = C.GIT_OBJ_COMMIT
+	OBJ_TREE ObjectType = C.GIT_OBJ_TREE
+	OBJ_BLOB ObjectType = C.GIT_OBJ_BLOB
+	OBJ_TAG ObjectType = C.GIT_OBJ_TAG
+)
+
+type Object interface {
+	Free()
+	Id() *Oid
+	Type() ObjectType
+}
+
+type gitObject struct {
+	ptr *C.git_object
+}
+
+func (t ObjectType) String() (string) {
+	switch (t) {
+	case OBJ_ANY:
+		return "Any"
+	case OBJ_BAD:
+		return "Bad"
+	case OBJ_COMMIT:
+		return "Commit"
+	case OBJ_TREE:
+		return "Tree"
+	case OBJ_BLOB:
+		return "Blob"
+	case OBJ_TAG:
+		return "tag"
+	}
+	// Never reached
+	return ""
+}
+
+func (o gitObject) Id() *Oid {
+	return newOidFromC(C.git_commit_id(o.ptr))
+}
+
+func (o gitObject) Type() ObjectType {
+	return ObjectType(C.git_object_type(o.ptr))
+}
+
+func (o *gitObject) Free() {
+	runtime.SetFinalizer(o, nil)
+	C.git_commit_free(o.ptr)
+}
+
+func allocObject(cobj *C.git_object) Object {
+
+	switch ObjectType(C.git_object_type(cobj)) {
+	case OBJ_COMMIT:
+		commit := &Commit{gitObject{cobj}}
+		runtime.SetFinalizer(commit, (*Commit).Free)
+		return commit
+
+	case OBJ_TREE:
+		tree := &Tree{gitObject{cobj}}
+		runtime.SetFinalizer(tree, (*Tree).Free)
+		return tree
+
+	case OBJ_BLOB:
+		blob := &Blob{gitObject{cobj}}
+		runtime.SetFinalizer(blob, (*Blob).Free)
+		return blob
+	}
+
+	return nil
+}