Fixes combined "and" and "or" rule handling

The text parser handles rules like below:

- A or B or C [or D...]
- A and B and C [and D...]

But it doesn't ones below:

- A or B and C
- A and B or C

So, this patch fixes them with:

- for "A and B or C": adds @reducer('and_expr', 'or', 'check') to
  _make_or_expr().

- for "A or B and C": adds _mix_or_and_expr() method. It pops the last
  check (B) from OrCheck rule list [A, B] and append AndCheck with
  rule list [B, C] to the Or Check rule list. So, finally we will get
  "OrCheck[A, AndCheck[B, C]]".

Change-Id: Iaaee4864356411374ee7e7c5c0c05b98889e0f4e
Closes-Bug: #1523030

1 files changed, 13 insertions, 0 deletions

diff --git a/oslo_policy/_parser.py b/oslo_policy/_parser.py
index 29be1b4..2225c2d 100644
--- a/oslo_policy/_parser.py
+++ b/oslo_policy/_parser.py
@@ -159,6 +159,18 @@ class ParseState(object):
 
         return [('and_expr', _checks.AndCheck([check1, check2]))]
 
+    @reducer('or_expr', 'and', 'check')
+    def _mix_or_and_expr(self, or_expr, _and, check):
+        """Modify the case 'A or B and C'"""
+
+        or_expr, check1 = or_expr.pop_check()
+        if isinstance(check1, _checks.AndCheck):
+            and_expr = check1
+            and_expr.add_check(check)
+        else:
+            and_expr = _checks.AndCheck([check1, check])
+        return [('or_expr', or_expr.add_check(and_expr))]
+
     @reducer('and_expr', 'and', 'check')
     def _extend_and_expr(self, and_expr, _and, check):
         """Extend an 'and_expr' by adding one more check."""
@@ -166,6 +178,7 @@ class ParseState(object):
         return [('and_expr', and_expr.add_check(check))]
 
     @reducer('check', 'or', 'check')
+    @reducer('and_expr', 'or', 'check')
     def _make_or_expr(self, check1, _or, check2):
         """Create an 'or_expr'.