_yaml: Remove 'node_extend_list' and add 'SequenceNode.append'

There was a single place using 'node_extend_list', which we can replace
more easily with 'SequenceNode.append'.

Also rewrite _projectrefs.py:_lookup to use the new API more effectively

4 files changed, 16 insertions, 80 deletions

diff --git a/src/buildstream/_projectrefs.py b/src/buildstream/_projectrefs.py
index d10456b14..c3e669c81 100644
--- a/src/buildstream/_projectrefs.py
+++ b/src/buildstream/_projectrefs.py
@@ -121,15 +121,16 @@ class ProjectRefs():
     # Looks up a ref node in the project.refs file, creates one if ensure is True.
     #
     def _lookup(self, toplevel, project, element, source_index, *, ensure=False):
+        projects = toplevel.get_mapping('projects')
+
         # Fetch the project
         try:
-            projects = toplevel.get_mapping('projects')
             project_node = projects.get_mapping(project)
         except LoadError:
             if not ensure:
                 return None
-            project_node = _yaml.new_empty_node(ref_node=projects)
-            projects[project] = project_node
+            projects[project] = {}
+            project_node = projects.get_mapping(project)
 
         # Fetch the element
         try:
@@ -137,8 +138,8 @@ class ProjectRefs():
         except LoadError:
             if not ensure:
                 return None
-            element_list = _yaml.new_empty_list_node()
-            project_node[element] = element_list
+            project_node[element] = []
+            element_list = project_node.get_sequence(element)
 
         # Fetch the source index
         try:
@@ -147,9 +148,7 @@ class ProjectRefs():
             if not ensure:
                 return None
 
-            # Pad the list with empty newly created dictionaries
-            _yaml.node_extend_list(project_node, element, source_index + 1, {})
-
-            node = project_node.get_sequence(element).mapping_at(source_index)
+            element_list.append({})
+            node = element_list.mapping_at(source_index)
 
         return node
diff --git a/src/buildstream/_yaml.pxd b/src/buildstream/_yaml.pxd
index 32a39dfd4..d7109bba5 100644
--- a/src/buildstream/_yaml.pxd
+++ b/src/buildstream/_yaml.pxd
@@ -67,6 +67,7 @@ cdef class ScalarNode(Node):
 
 
 cdef class SequenceNode(Node):
+    cpdef void append(self, object value)
     cpdef MappingNode mapping_at(self, int index)
     cpdef SequenceNode sequence_at(self, int index)
     cpdef list as_str_list(self)
diff --git a/src/buildstream/_yaml.pyx b/src/buildstream/_yaml.pyx
index fe5cdd426..b717b2eb3 100644
--- a/src/buildstream/_yaml.pyx
+++ b/src/buildstream/_yaml.pyx
@@ -558,6 +558,13 @@ cdef class SequenceNode(Node):
         self.line = line
         self.column = column
 
+    cpdef void append(self, object value):
+        if type(value) in [MappingNode, ScalarNode, SequenceNode]:
+            self.value.append(value)
+        else:
+            node = _create_node_recursive(value, self)
+            self.value.append(node)
+
     cpdef SequenceNode copy(self):
         cdef list copy = []
         cdef Node entry
@@ -943,19 +950,6 @@ cdef class Representer:
         return RepresenterState.init
 
 
-cdef Node _create_node(object value, int file_index, int line, int column):
-    cdef type_value = type(value)
-
-    if type_value in [bool, str, type(None), int]:
-        return ScalarNode(value, file_index, line, column)
-    elif type_value is dict:
-        return MappingNode(value, file_index, line, column)
-    elif type_value is list:
-        return SequenceNode(value, file_index, line, column)
-    raise ValueError(
-        "Node values can only be 'list', 'dict', 'bool', 'str', 'int' or None. Not {}".format(type_value))
-
-
 cdef Node _create_node_recursive(object value, Node ref_node):
     cdef value_type = type(value)
 
@@ -1097,50 +1091,6 @@ cpdef ProvenanceInformation node_get_provenance(Node node, str key=None, list in
     return ProvenanceInformation(nodeish)
 
 
-# node_extend_list()
-#
-# Extend a list inside a node to a given length, using the passed
-# default value to fill it out.
-#
-# Valid default values are:
-#    Any string
-#    An empty dict
-#    An empty list
-#
-# Args:
-#    node (node): The node
-#    key (str): The list name in the node
-#    length (int): The length to extend the list to
-#    default (any): The default value to extend with.
-def node_extend_list(Node node, str key, Py_ssize_t length, object default):
-    assert type(default) is str or default in ([], {})
-
-    cdef Node list_node = <Node> node.value.get(key)
-    if list_node is None:
-        list_node = node.value[key] = SequenceNode([], node.file_index, node.line, next_synthetic_counter())
-
-    cdef list the_list = list_node.value
-    def_type = type(default)
-
-    file_index = node.file_index
-    if the_list:
-        line_num = the_list[-1][2]
-    else:
-        line_num = list_node.line
-
-    while length > len(the_list):
-        if def_type is str:
-            value = default
-        elif def_type is list:
-            value = []
-        else:
-            value = {}
-
-        line_num += 1
-
-        the_list.append(_create_node(value, file_index, line_num, next_synthetic_counter()))
-
-
 # is_node()
 #
 # A test method which returns whether or not the passed in value
diff --git a/tests/internals/yaml.py b/tests/internals/yaml.py
index 9b3269d46..69f29a573 100644
--- a/tests/internals/yaml.py
+++ b/tests/internals/yaml.py
@@ -273,20 +273,6 @@ def test_list_deletion(datafiles):
     assert not children
 
 
-# Test that extending a non-existent list works as expected
-@pytest.mark.datafiles(os.path.join(DATA_DIR))
-def test_nonexistent_list_extension(datafiles):
-    base = os.path.join(datafiles.dirname, datafiles.basename, 'basics.yaml')
-
-    base = _yaml.load(base, shortname='basics.yaml')
-    assert 'todo' not in base
-
-    _yaml.node_extend_list(base, 'todo', 3, 'empty')
-
-    assert len(base.get_sequence('todo')) == 3
-    assert base.get_sequence('todo').as_str_list() == ['empty', 'empty', 'empty']
-
-
 # Tests for deep list composition
 #
 # Same as test_list_composition(), but adds an additional file