Add helper script to add things to YAML

1 files changed, 78 insertions, 0 deletions

diff --git a/yaml-add b/yaml-add
new file mode 100755
index 0000000..b6d375c
--- /dev/null
+++ b/yaml-add
@@ -0,0 +1,78 @@
+#!/usr/bin/env python2
+# Copyright 2015  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+'''Add things to a YAML file.
+
+Read an object from a YAML file. The object must be a dictionary. Add
+a new value to the dictionary, or a sub-dictionary. Save the object
+back to its original file.
+
+Example:
+
+    echo '{}' > foo.ick
+    yaml-add foo.ick key1 key2 value
+
+This would result in:
+
+    key1:
+        key2: value
+
+If there is already a value, the value is made into a list and the new
+value appended to the list. If the value is already a list, the value
+is appended to the list.
+
+'''
+
+
+import sys
+
+import yaml
+
+
+if len(sys.argv) < 4:
+    sys.stderr.write('too few args\n')
+    sys.exit(1)
+
+
+with open(sys.argv[1]) as f:
+    obj = yaml.safe_load(f)
+
+
+keys = sys.argv[2:-1]
+value = sys.argv[-1]
+print keys
+print value
+
+thing = obj
+for key in keys[:-1]:
+    if key not in thing:
+        thing[key] = {}
+    thing = thing[key]
+
+key = keys[-1]
+old_value = thing.get(key)
+if old_value is None:
+    thing[key] = value
+elif type(old_value) is list:
+    old_value.append(value)
+else:
+    thing[key] = [old_value, value]
+
+with open(sys.argv[1], 'w') as f:
+    yaml.safe_dump(obj, stream=f, default_flow_style=False, indent=4)