Reference: implement peel()

This makes both objects and references peelable via the same interface,
simplifying how to get to the wanted type.

docs/references.rst

@@ -28,6 +28,7 @@ The Reference type
 .. automethod:: pygit2.Reference.delete
 .. automethod:: pygit2.Reference.rename
 .. automethod:: pygit2.Reference.resolve
+.. automethod:: pygit2.Reference.peel
 .. automethod:: pygit2.Reference.log
 
    Example::

src/object.c

@@ -135,24 +135,6 @@ Object_read_raw(Object *self)
     return aux;
 }
 
-static git_otype
-py_type_to_git_type(PyTypeObject *py_type)
-{
-    git_otype type = GIT_OBJ_BAD;
-
-    if (py_type == &CommitType) {
-        type = GIT_OBJ_COMMIT;
-    } else if (py_type == &TreeType) {
-        type = GIT_OBJ_TREE;
-    } else if (py_type == &BlobType) {
-        type = GIT_OBJ_BLOB;
-    } else if (py_type == &TagType) {
-        type = GIT_OBJ_TAG;
-    }
-
-    return type;
-}
-
 PyDoc_STRVAR(Object_peel__doc__,
   "peel(target_type) -> Object\n"
   "\n"
@@ -164,18 +146,9 @@ Object_peel(Object *self, PyObject *py_type)
     int type = -1, err;
     git_object *peeled;
 
-    if (PyLong_Check(py_type)) {
-        type = PyLong_AsLong(py_type);
-        if (type == -1 && PyErr_Occurred())
-            return NULL;
-    } else if (PyType_Check(py_type)) {
-        type = py_type_to_git_type((PyTypeObject *) py_type);
-    }
-
-    if (type == -1) {
-        PyErr_SetString(PyExc_ValueError, "invalid target type");
+    type = py_object_to_object_type(py_type);
+    if (type == -1)
         return NULL;
-    }
 
     err = git_object_peel(&peeled, self->obj, (git_otype)type);
     if (err < 0)

src/reference.c

@@ -384,6 +384,29 @@ Reference_get_object(Reference *self)
     return wrap_object(obj, self->repo);
 }
 
+PyDoc_STRVAR(Reference_peel__doc__,
+  "peel(type) -> object\n"
+  "\n"
+  "Retrieve an object of the given type by recursive peeling.");
+
+PyObject *
+Reference_peel(Reference *self, PyObject *py_type)
+{
+    int err, type;
+    git_object *obj;
+
+    CHECK_REFERENCE(self);
+
+    type = py_object_to_object_type(py_type);
+    if (type == -1)
+        return NULL;
+
+    err = git_reference_peel(&obj, self->reference, type);
+    if (err < 0)
+        return Error_set(err);
+
+    return wrap_object(obj, self->repo);
+}
 
 PyDoc_STRVAR(RefLogEntry_committer__doc__, "Committer.");
 
@@ -479,6 +502,7 @@ PyMethodDef Reference_methods[] = {
     METHOD(Reference, log, METH_NOARGS),
     METHOD(Reference, get_object, METH_NOARGS),
     METHOD(Reference, set_target, METH_VARARGS | METH_KEYWORDS),
+    METHOD(Reference, peel, METH_O),
     {NULL}
 };
 

src/utils.c

@@ -31,6 +31,10 @@
 #include "utils.h"
 
 extern PyTypeObject ReferenceType;
+extern PyTypeObject TreeType;
+extern PyTypeObject CommitType;
+extern PyTypeObject BlobType;
+extern PyTypeObject TagType;
 
 /**
  * py_str_to_c_str() returns a newly allocated C string holding the string
@@ -153,3 +157,41 @@ on_error:
 
     return -1;
 }
+
+static git_otype
+py_type_to_git_type(PyTypeObject *py_type)
+{
+    git_otype type = GIT_OBJ_BAD;
+
+    if (py_type == &CommitType) {
+        type = GIT_OBJ_COMMIT;
+    } else if (py_type == &TreeType) {
+        type = GIT_OBJ_TREE;
+    } else if (py_type == &BlobType) {
+        type = GIT_OBJ_BLOB;
+    } else if (py_type == &TagType) {
+        type = GIT_OBJ_TAG;
+    }
+
+    return type;
+}
+
+int
+py_object_to_object_type(PyObject *py_type)
+{
+    int type = -1;
+
+    if (PyLong_Check(py_type)) {
+        type = PyLong_AsLong(py_type);
+        if (type == -1 && PyErr_Occurred())
+            return -1;
+    } else if (PyType_Check(py_type)) {
+        type = py_type_to_git_type((PyTypeObject *) py_type);
+    }
+
+    if (type == -1) {
+        PyErr_SetString(PyExc_ValueError, "invalid target type");
+    }
+
+    return type;
+}

src/utils.h

@@ -119,6 +119,8 @@ const char *py_str_borrow_c_str(PyObject **tvaue, PyObject *value, const char *e
 PyObject * get_pylist_from_git_strarray(git_strarray *strarray);
 int get_strarraygit_from_pylist(git_strarray *array, PyObject *pylist);
 
+int py_object_to_object_type(PyObject *py_type);
+
 #define py_path_to_c_str(py_path) \
         py_str_to_c_str(py_path, Py_FileSystemDefaultEncoding)
 

test/test_refs.py

@@ -32,6 +32,7 @@ from __future__ import unicode_literals
 import unittest
 
 from pygit2 import GitError, GIT_REF_OID, GIT_REF_SYMBOLIC, Signature
+from pygit2 import Commit, Tree
 from . import utils
 
 
@@ -223,6 +224,11 @@ class ReferencesTest(utils.RepoTestCase):
         ref = repo.lookup_reference('refs/heads/master')
         self.assertEqual(repo[ref.target].id, ref.get_object().id)
 
+    def test_peel(self):
+        ref = self.repo.lookup_reference('refs/heads/master')
+        commit = ref.peel(Commit)
+        self.assertEqual(commit.tree.id, ref.peel(Tree).id)
+
 
 if __name__ == '__main__':
     unittest.main()