_yaml: Remove 'key' from node_find_target

- node_find_target with 'key' is only used once in the codebase.
  We can remove and simplify this function
- Allow 'MappingNode.get_node()' to be called without any
  'expected_types'

3 files changed, 7 insertions, 12 deletions

diff --git a/src/buildstream/_yaml.pxd b/src/buildstream/_yaml.pxd
index 98ea64b28..6e4fd6218 100644
--- a/src/buildstream/_yaml.pxd
+++ b/src/buildstream/_yaml.pxd
@@ -33,7 +33,7 @@ cdef class Node:
 cdef class MappingNode(Node):
     cdef Node get(self, str key, default, default_constructor)
     cpdef MappingNode get_mapping(self, str key, default=*)
-    cpdef Node get_node(self, str key, list allowed_types, bint allow_none=*)
+    cpdef Node get_node(self, str key, list allowed_types=*, bint allow_none=*)
     cpdef ScalarNode get_scalar(self, str key, default=*)
     cpdef SequenceNode get_sequence(self, str key, object default=*)
     cpdef bint get_bool(self, str key, default=*) except *
diff --git a/src/buildstream/_yaml.pyx b/src/buildstream/_yaml.pyx
index 6d5ac9508..ef1a7f015 100644
--- a/src/buildstream/_yaml.pyx
+++ b/src/buildstream/_yaml.pyx
@@ -173,7 +173,7 @@ cdef class MappingNode(Node):
 
         return value
 
-    cpdef Node get_node(self, str key, list allowed_types, bint allow_none = False):
+    cpdef Node get_node(self, str key, list allowed_types = None, bint allow_none = False):
         cdef value = self.value.get(key, _sentinel)
 
         if value is _sentinel:
@@ -184,7 +184,7 @@ cdef class MappingNode(Node):
             raise LoadError(LoadErrorReason.INVALID_DATA,
                             "{}: Dictionary did not contain expected key '{}'".format(provenance, key))
 
-        if type(value) not in allowed_types:
+        if allowed_types and type(value) not in allowed_types:
             provenance = node_get_provenance(self)
             raise LoadError(LoadErrorReason.INVALID_DATA,
                             "{}: Value of '{}' is not one of the following: {}.".format(
@@ -1342,19 +1342,12 @@ def assert_symbol_name(ProvenanceInformation provenance, str symbol_name, str pu
 # Args:
 #    node (Node): The node at the root of the tree to search
 #    target (Node): The node you are looking for in that tree
-#    key (str): Optional string key within target node
 #
 # Returns:
 #    (list): A path from `node` to `target` or None if `target` is not in the subtree
-cpdef list node_find_target(MappingNode node, Node target, str key=None):
-    if key is not None:
-        target = target.value[key]
-
+cpdef list node_find_target(MappingNode node, Node target):
     cdef list path = []
     if _walk_find_target(node, path, target):
-        if key:
-            # Remove key from end of path
-            path = path[:-1]
         return path
     return None
 
diff --git a/src/buildstream/source.py b/src/buildstream/source.py
index 6d65811be..2274f47d9 100644
--- a/src/buildstream/source.py
+++ b/src/buildstream/source.py
@@ -970,7 +970,9 @@ class Source(Plugin):
             if action == 'add':
                 path = _yaml.node_find_target(toplevel_node, node)
             else:
-                path = _yaml.node_find_target(toplevel_node, node, key=key)
+                full_path = _yaml.node_find_target(toplevel_node, node.get_node(key))
+                # We want the path to the node containing the key, not to the key
+                path = full_path[:-1]
 
             roundtrip_file = roundtrip_cache.get(provenance.filename)
             if not roundtrip_file: