allow constant truth values in boolean conditions

Author: jeff-k

pyvdrm/asi2.py

@@ -83,6 +83,18 @@ def __call__(self, mutations):
         return Score(not child_score.score, child_score.residues)
 
 
+class BoolTrue(AsiExpr):
+    """Boolean True constant"""
+    def __call__(self, *args):
+        return Score(True, [])
+
+
+class BoolFalse(AsiExpr):
+    """Boolean False constant"""
+    def __call__(self, *args):
+        return Score(False, [])
+
+
 class AndExpr(AsiExpr):
     """Fold boolean AND on children"""
 
@@ -279,8 +291,11 @@ def parser(self, rule):
         selectstatement = select + select_quantifier + from_ + residue_list
         selectstatement.setParseAction(SelectFrom)
 
+        bool_ = Literal('TRUE').suppress().setParseAction(BoolTrue) |\
+                Literal('FALSE').suppress().setParseAction(BoolFalse)
+
         booleancondition = Forward()
-        condition = residue | excludestatement | selectstatement
+        condition = residue | excludestatement | selectstatement | bool_
 
         booleancondition << infixNotation(condition,
                                           [(and_, 2, opAssoc.LEFT, AndExpr),

pyvdrm/tests/test_asi2.py

@@ -81,6 +81,14 @@ def test_bool_and(self):
         self.assertEqual(rule(VariantCalls("7Y 1G 2T")), True)
         self.assertEqual(rule([]), False)
 
+    def test_bool_constants(self):
+        rule = ASI2("TRUE OR 1G")
+        self.assertEqual(rule(VariantCalls("2G")), True)
+        rule = ASI2("FALSE AND 1G")
+        self.assertEqual(rule(VariantCalls("1G")), False)
+        rule = ASI2("TRUE OR (FALSE AND TRUE)")
+        self.assertEqual(rule(VariantCalls("1G")), True)
+
     def test_bool_or(self):
         rule = ASI2("1G OR (2T OR 7Y)")
         self.assertTrue(rule(VariantCalls("2T")))