Python: add YAML dbscheme fragment

Author: aibaars

python/ql/lib/semmlecode.python.dbscheme

@@ -1104,3 +1104,44 @@ xmllocations(int xmlElement: @xmllocatable ref,
              int location: @location_default ref);
 
 @xmllocatable = @xmlcharacters | @xmlelement | @xmlcomment | @xmlattribute | @xmldtd | @file | @xmlnamespace;
+
+/**
+ *  YAML
+ */
+
+#keyset[parent, idx]
+yaml (unique int id: @yaml_node,
+      int kind: int ref,
+      int parent: @yaml_node_parent ref,
+      int idx: int ref,
+      varchar(900) tag: string ref,
+      varchar(900) tostring: string ref);
+
+case @yaml_node.kind of
+  0 = @yaml_scalar_node
+| 1 = @yaml_mapping_node
+| 2 = @yaml_sequence_node
+| 3 = @yaml_alias_node
+;
+
+@yaml_collection_node = @yaml_mapping_node | @yaml_sequence_node;
+
+@yaml_node_parent = @yaml_collection_node | @file;
+
+yaml_anchors (unique int node: @yaml_node ref,
+              varchar(900) anchor: string ref);
+
+yaml_aliases (unique int alias: @yaml_alias_node ref,
+              varchar(900) target: string ref);
+
+yaml_scalars (unique int scalar: @yaml_scalar_node ref,
+              int style: int ref,
+              varchar(900) value: string ref);
+
+yaml_errors (unique int id: @yaml_error,
+             varchar(900) message: string ref);
+
+yaml_locations(unique int locatable: @yaml_locatable ref,
+             int location: @location_default ref);
+
+@yaml_locatable = @yaml_node | @yaml_error;