Support YAML metadata (Issue #2801)

CHANGES.txt

@@ -1,3 +1,11 @@
+New in master
+=============
+
+Features
+--------
+
+* Support for YAML metadata (Issue #2801)
+
 New in v7.8.6
 =============
 

nikola/post.py

@@ -51,6 +51,10 @@
     import pyphen
 except ImportError:
     pyphen = None
+try:
+    import yaml
+except ImportError:
+    yaml = None
 
 from math import ceil  # for reading time feature
 
@@ -1023,6 +1027,17 @@ def _get_metadata_from_file(meta_data):
     if not meta_data[0]:
         meta_data = meta_data[1:]
 
+    # If 1st line is '---', then it's YAML metadata
+    if meta_data[0] == '---':
+        if yaml is None:
+            utils.req_missing('pyyaml', 'use YAML metadata')
+        idx = meta_data.index('---', 1)
+        meta = yaml.load('\n'.join(meta_data[1:idx]))
+        # We expect empty metadata to be '', not None
+        for k in meta:
+            if meta[k] is None:
+                meta[k] = ''
+
     # First, get metadata from the beginning of the file,
     # up to first empty line
 

requirements.txt

@@ -13,3 +13,4 @@ setuptools>=20.3
 natsort>=3.5.2
 requests>=2.2.0
 piexif>=1.0.3
+PyYAML==3.12