_yaml: Introduce 'get_sequence()' and 'sequence_at()'/'mapping_at()'

- Adding 'get_sequence' on MappingNode to access sequences in a mapping
- Adding 'sequence_at' on SequenceNode to access sequences in a sequence
- Adding 'mapping_at' on SequenceNode to access mappings in a sequence

Using "*_at" in sequences allows us to quickly understand if we are
dealing with a sequence or a mapping.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/buildstream/_gitsourcebase.py b/src/buildstream/_gitsourcebase.py
index 61ecd36eb..4837877f4 100644
--- a/src/buildstream/_gitsourcebase.py
+++ b/src/buildstream/_gitsourcebase.py
@@ -383,7 +383,7 @@ class _GitSourceBase(Source):
                        'track-tags', 'tags']
         self.node_validate(node, config_keys + Source.COMMON_CONFIG_KEYS)
 
-        tags_node = self.node_get_member(node, list, 'tags', [])
+        tags_node = node.get_sequence('tags', [])
         for tag_node in tags_node:
             self.node_validate(tag_node, ['tag', 'commit', 'annotated'])
 
@@ -663,7 +663,7 @@ class _GitSourceBase(Source):
 
     def _load_tags(self, node):
         tags = []
-        tags_node = self.node_get_member(node, list, 'tags', [])
+        tags_node = node.get_sequence('tags', [])
         for tag_node in tags_node:
             tag = tag_node.get_str('tag')
             commit_ref = tag_node.get_str('commit')