Merge pull request #11 from dshen109/master

Namespace Traversal

pytool/__init__.py

@@ -14,7 +14,7 @@
     limitations under the License.
 
 """
-__version__ = '3.8.1'
+__version__ = '3.9.0'
 
 
 from pytool import (

pytool/lang.py

@@ -402,6 +402,10 @@ class Namespace(object):
 
         Added dict-like access capability to Namespaces.
 
+    .. versionadded:: 3.9.0
+
+        Added traversal by key/index arrays for nested Namespaces and lists
+
     """
     def __init__(self, obj=None):
         if obj is not None:
@@ -532,6 +536,36 @@ def copy(self, *args, **kwargs):
     __copy__ = copy
     __deepcopy__ = copy
 
+    def traverse(self, path):
+        """ Traverse the Namespace and any nested elements by following the
+            elements in an iterable *path* and return the item found at the end
+            of *path*.
+
+            Traversal is achieved using the __getitem__ method, allowing for
+            traversal of nested structures such as arrays and dictionaries.
+
+            AttributeError is raised if one of the attributes in *path* does
+            not exist at the expected depth.
+
+            :param iterable path: An iterable whose elements specify the keys
+                to path over.
+
+        Example:
+
+            ns = Namespace({"foo":
+                            [Namespace({"name": "john"}),
+                             Namespace({"name": "jane"})]})
+            ns.traverse(["foo", 1, "name"])
+
+            ... returns ...
+
+            "jane"
+        """
+        struct = self
+        for k in path:
+            struct = struct[k]
+        return struct
+
 
 def _split_keys(obj):
     """

test/test_lang.py

@@ -544,3 +544,38 @@ def test_namespace_copy_api_list():
     ns2.foo[0].bar.baz = 2
 
     eq_(ns.foo[0].bar.baz, 1)
+
+
+def test_namespace_traverse():
+    ns = pytool.lang.Namespace()
+    ns.foo.bar = "foobar"
+    val = ns.traverse(["foo", "bar"])
+
+    eq_(val, "foobar")
+
+
+def test_namespace_traverse_list():
+    ns = pytool.lang.Namespace({"foo":
+                                [pytool.lang.Namespace({"name": "john"}),
+                                 pytool.lang.Namespace({"name": "jane"})]})
+    name = ns.traverse(["foo", 0, "name"])
+
+    eq_(name, "john")
+
+
+def test_namespace_traverse_dict():
+    ns = pytool.lang.Namespace()
+    ns.foo = {"first": pytool.lang.Namespace({"color": "red"}),
+              "second": pytool.lang.Namespace({"color": "blue"})}
+    val = ns.traverse(["foo", "second", "color"])
+
+    eq_(val, "blue")
+
+
+@raises(AttributeError)
+def test_namespace_traverse_failure():
+    ns = pytool.lang.Namespace()
+
+    ns.traverse(["foo"])
+
+    eq_(ns.as_dict(), {})