yaml literals

setup.cfg

@@ -52,6 +52,7 @@ console_scripts =
 
 [options.extras_require]
 toml = tomli
+yaml = pyyaml
 
 [scriv]
 version = literal: src/scriv/__init__.py: __version__

src/scriv/literals.py

@@ -11,6 +11,10 @@
 except ImportError:  # pragma: no cover
     tomli = None  # type: ignore
 
+try:
+    import yaml
+except ImportError:  # pragma: no cover
+    yaml = None  # type: ignore
 
 def find_literal(file_name: str, literal_name: str) -> Optional[str]:
     """
@@ -35,6 +39,16 @@ def find_literal(file_name: str, literal_name: str) -> Optional[str]:
         with open(file_name, encoding="utf-8") as f:
             data = tomli.loads(f.read())
         return find_toml_value(data, literal_name)
+    elif ext == ".yml" or ext == ".yaml":
+        if yaml is None:
+            msg = (
+                "Can't read {!r} without yaml support. "
+                + "Install with [yaml] extra"
+            ).format(file_name)
+            raise Exception(msg)
+        with open(file_name, encoding="utf-8") as f:
+            data = yaml.safe_load(f.read())
+        return find_yaml_value(data, literal_name)
     else:
         raise Exception(f"Can't read literals from files like {file_name!r}")
 
@@ -98,3 +112,20 @@ def find_toml_value(data: MutableMapping[str, Any], name: str) -> Optional[str]:
     if isinstance(current_object, str):
         return current_object
     return None
+
+def find_yaml_value(data: MutableMapping[str, Any], name: str) -> Optional[str]:
+    """
+    Use a period-separated name to traverse a dictionary.
+
+    Only string values are supported.
+    """
+    current_object = data
+    for key in name.split("."):
+        try:
+            current_object = current_object[key]
+        except (KeyError, TypeError):
+            return None
+
+    if isinstance(current_object, str):
+        return current_object
+    return None