feat(filter): add some set theory filters

plugins/filter/base.py

@@ -0,0 +1,37 @@
+import collections
+import re
+
+from ansible.errors import AnsibleFilterError
+
+
+def consensus(pipe_in: dict[str], set: bool = False, msg=""):
+    apply = FilterModule.xset if set else id
+    [head, *tail] = map(apply, pipe_in.values())
+    if not all(head == x for x in tail):
+        raise AnsibleFilterError(msg or "No consensus", pipe_in)
+    return head
+
+
+def split2multidict(pipe_in, sep=None):
+    result = collections.defaultdict(list)
+    for key, val in map(lambda line: line.split(sep, 1), pipe_in):
+        result[key].append(val)
+    return result
+
+
+def regex_replace(pipe_in, pattern, repl, count=0, require_n=0):
+    result, actual_n = re.subn(pattern, repl, pipe_in, count=count)
+    if require_n not in {0, actual_n}:
+        raise AnsibleFilterError("unexpected substitution count")
+    return result
+
+
+class FilterModule(object):
+    xset = set
+
+    def filters(self):
+        return {
+            "consensus": consensus,
+            "split2multidict": split2multidict,
+            "regex_replace": regex_replace,
+        }