added the yaml utility for the gitlab ci

cbutil/yaml_util.py

+import yaml
+
+
+class Reference:
+    yaml_tag = '!reference'
+
+    def __init__(self, values):
+        self._values = values
+
+
+def reference_constructor(loader: yaml.SafeLoader, node: yaml.nodes.CollectionNode) -> Reference:
+    return Reference(loader.construct_sequence(node))
+
+
+def reference_representer(dumper: yaml.SafeDumper, ref: Reference) -> yaml.nodes.SequenceNode:
+    return dumper.represent_sequence(Reference.yaml_tag, ref._values, flow_style=True)
+
+
+def loader():
+    loader = yaml.SafeLoader
+    loader.add_constructor(Reference.yaml_tag, reference_constructor)
+    return loader
+
+
+def dumper():
+    dumper = yaml.SafeDumper
+    dumper.add_representer(Reference, reference_representer)
+    dumper.ignore_aliases = lambda *args: True
+    return dumper
+
+
+def load_script(raw_strings):
+    if isinstance(raw_strings, str):
+        raw_strings = [raw_strings]
+    for raw_string in raw_strings:
+        yield yaml.load(raw_string, Loader=loader())
+
+
+def print_yaml_file(config: dict) -> str:
+    return yaml.dump(config,
+                     default_flow_style=False,
+                     line_break=False,
+                     width=120,
+                     Dumper=dumper(),
+                     sort_keys=False)

pyproject.toml

@@ -18,6 +18,7 @@ dependencies = [
     "numpy",
     "pandas",
     "importlib_resources ; python_version<'3.7'",
+    "pyyaml",
 ]
 
 [project.optional-dependencies]

tests/test_yaml_util.py

+from cbutil.yaml_util import load_script, dumper
+import yaml
+
+
+def test_load_script():
+    test_string = "before_script:\n -!reference [.load_cbutil, script]\n"""
+    actual = yaml.dump(next(load_script(test_string)), Dumper=dumper())
+    assert actual.replace(" ", "").replace("\n", "") == test_string.replace(" ", "").replace("\n", "")