Make sorting in climb() and prune() configurable (#271)

Allow users to disable sorting by node names and preserve the
order in which child nodes where inserted into the tree.

docs/modules.rst

@@ -3,6 +3,29 @@
     Modules
 ===============
 
+.. _sort:
+
+Sort
+----
+
+By default, when exploring test metadata in the tree, child nodes
+are sorted alphabetically by node name. This applies to command
+line usage such as ``fmf ls`` or ``fmf show`` as well as for the
+:py:meth:`fmf.Tree.climb()` and :py:meth:`fmf.Tree.prune()`
+methods.
+
+If the tree content is not created from files on disk but created
+manually using the :py:meth:`fmf.Tree.child()` method, the child
+order can be preserved by providing the ``sort=False`` parameter
+to the :py:meth:`fmf.Tree.climb()` and :py:meth:`fmf.Tree.prune()`
+methods.
+
+.. versionadded:: 1.6
+
+
+fmf
+---
+
 .. automodule:: fmf
     :members:
     :undoc-members:

docs/releases.rst

@@ -12,6 +12,12 @@ In order to search :ref:`context` dimension values using regular
 expressions, it is now possible to use operator ``~`` for matching
 patterns and operator ``!~`` for non matching patterns.
 
+When exploring trees using the :py:meth:`fmf.Tree.climb()` and
+:py:meth:`fmf.Tree.prune()` methods, optional parameter ``sort``
+can be used to preserve the original order in which child nodes
+where inserted into the tree. See the :ref:`sort` section for more
+details.
+
 
 fmf-1.5.0
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

fmf/base.py

@@ -707,12 +707,33 @@ def grow(self, path):
                 del self.children[name]
                 log.debug("Empty tree '{0}' removed.".format(child.name))
 
-    def climb(self, whole=False):
-        """ Climb through the tree (iterate leaf/all nodes) """
+    def climb(self, whole: bool = False, sort: bool = True):
+        """
+        Climb through the tree (iterate over nodes)
+
+        :param whole: By default only leaf nodes are considered. When
+            set to ``True`` all nodes are iterated, including parent
+            branches.
+
+        :param sort: When iterating, child nodes are sorted by name by
+            default. Set to ``False`` if you prefer to keep the order in
+            which the child nodes were inserted into the tree.
+        """
+
+        # Include branches when `whole` is enabled or the `select`
+        # directive has been used to pick this node.
         if whole or self.select:
             yield self
-        for name, child in sorted(self.children.items()):
-            for node in child.climb(whole):
+
+        # Sort child nodes by name only if requested
+        if sort:
+            children = [child for _, child in sorted(self.children.items())]
+        else:
+            children = self.children.values()
+
+        # Iterate through each child node
+        for child in children:
+            for node in child.climb(whole=whole, sort=sort):
                 yield node
 
     @property
@@ -730,9 +751,36 @@ def find(self, name):
                 return node
         return None
 
-    def prune(self, whole=False, keys=None, names=None, filters=None,
-              conditions=None, sources=None):
-        """ Filter tree nodes based on given criteria """
+    def prune(
+            self,
+            whole: bool = False,
+            keys: Optional[list[str]] = None,
+            names: Optional[list[str]] = None,
+            filters: Optional[list[str]] = None,
+            conditions: Optional[list[str]] = None,
+            sources: Optional[list[str]] = None,
+            sort: bool = True):
+        """
+        Filter tree nodes based on given criteria
+
+        :param whole: By default only leaf nodes are considered. When
+            set to ``True`` all nodes are iterated, including parent
+            branches.
+
+        :param keys: Include only nodes containing given keys.
+
+        :param names: Include only nodes matching provided names.
+
+        :param filters: Include only nodes matching given filters.
+
+        :param conditions: Include only nodes satisfying the conditions.
+
+        :param sources: Filter by source fmf file names on disk.
+
+        :param sort: When iterating, child nodes are sorted by name by
+            default. Set to ``False`` if you prefer to keep the order in
+            which the child nodes were inserted into the tree.
+        """
         keys = keys or []
         names = names or []
         filters = filters or []
@@ -742,7 +790,7 @@ def prune(self, whole=False, keys=None, names=None, filters=None,
         if sources:
             sources = {os.path.abspath(src) for src in sources}
 
-        for node in self.climb(whole):
+        for node in self.climb(whole, sort=sort):
             # Select only nodes with key content
             if not all([key in node.data for key in keys]):
                 continue

tests/unit/test_base.py

@@ -80,6 +80,27 @@ def test_subtrees(self):
         child = Tree(EXAMPLES + "child")
         assert child.find("/nobody") is None
 
+    def test_insert_child(self):
+        """ Manual child creation """
+
+        # Prepare a simple tree by manually inserting child nodes
+        tree = Tree(data={"key": "value"})
+        tree.child(name="child2", data={"key": "value"})
+        tree.child(name="child3", data={"key": "value"})
+        tree.child(name="child1", data={"key": "value"})
+
+        # By default, node names should be sorted when climbing & prunning
+        expected = ['/child1', '/child2', '/child3']
+        assert [node.name for node in tree.climb()] == expected
+        assert [node.name for node in tree.prune()] == expected
+        assert [node.name for node in tree.climb(sort=True)] == expected
+        assert [node.name for node in tree.prune(sort=True)] == expected
+
+        # Original order should be kept if requested
+        expected = ['/child2', '/child3', '/child1']
+        assert [node.name for node in tree.climb(sort=False)] == expected
+        assert [node.name for node in tree.prune(sort=False)] == expected
+
     def test_prune_sources(self):
         """ Pruning by sources """
         original_directory = os.getcwd()