implemented xor in evaluation

Author: ashwin6-dev

evaluation_function/domain/__init__.py

@@ -8,6 +8,7 @@
     Disjunction,
     Implication,
     Biconditional,
+    Xor,
 )
 from .evaluators import (
     Assignment,
@@ -27,6 +28,7 @@
     "Disjunction",
     "Implication",
     "Biconditional",
+    "Xor",
     "Assignment",
     "FormulaEvaluator",
     "EquivalenceEvaluator",

evaluation_function/domain/evaluators.py

@@ -10,6 +10,7 @@
     Disjunction,
     Implication,
     Biconditional,
+    Xor,
 )
 
 
@@ -51,6 +52,10 @@ def _evaluate_formula(self, formula: Formula) -> bool:
             return not self._evaluate_formula(formula.left) or self._evaluate_formula(formula.right)
         if isinstance(formula, Biconditional):
             return self._evaluate_formula(formula.left) == self._evaluate_formula(formula.right)
+        if isinstance(formula, Xor):
+            left_val = self._evaluate_formula(formula.left)
+            right_val = self._evaluate_formula(formula.right)
+            return left_val != right_val
         raise TypeError(f"Unknown formula type: {type(formula)}")
 
 
@@ -63,7 +68,7 @@ def _extract_atoms(formula: Formula) -> Set[Atom]:
         pass
     elif isinstance(formula, Negation):
         atoms.update(_extract_atoms(formula.operand))
-    elif isinstance(formula, (Conjunction, Disjunction, Implication, Biconditional)):
+    elif isinstance(formula, (Conjunction, Disjunction, Implication, Biconditional, Xor)):
         atoms.update(_extract_atoms(formula.left))
         atoms.update(_extract_atoms(formula.right))
 

evaluation_function/domain/formula.py

@@ -149,3 +149,8 @@ def _operator_symbol(self) -> str:
 class Biconditional(BinaryOperator):
     def _operator_symbol(self) -> str:
         return "↔"
+
+
+class Xor(BinaryOperator):
+    def _operator_symbol(self) -> str:
+        return "⊕"

evaluation_function/parsing/binary_operator_builder.py

@@ -1,5 +1,5 @@
 from typing import Dict, Callable
-from ..domain.formula import Formula, Conjunction, Disjunction, Implication, Biconditional
+from ..domain.formula import Formula, Conjunction, Disjunction, Implication, Biconditional, Xor
 from .token_stream import TokenStream
 from .token import TokenType
 from .expression_builder import ExpressionBuilder
@@ -9,15 +9,17 @@ class BinaryOperatorBuilder(ExpressionBuilder):
     _PRECEDENCE: Dict[TokenType, int] = {
         TokenType.BICONDITIONAL: 1,
         TokenType.IMPLICATION: 2,
-        TokenType.DISJUNCTION: 3,
-        TokenType.CONJUNCTION: 4,
+        TokenType.XOR: 3,
+        TokenType.DISJUNCTION: 4,
+        TokenType.CONJUNCTION: 5,
     }
 
     _OPERATOR_CONSTRUCTORS: Dict[TokenType, Callable[[Formula, Formula], Formula]] = {
         TokenType.CONJUNCTION: Conjunction,
         TokenType.DISJUNCTION: Disjunction,
         TokenType.IMPLICATION: Implication,
         TokenType.BICONDITIONAL: Biconditional,
+        TokenType.XOR: Xor,
     }
 
     _RIGHT_ASSOCIATIVE: set = {TokenType.IMPLICATION}

evaluation_function/parsing/token.py

@@ -10,6 +10,7 @@ class TokenType(Enum):
     DISJUNCTION = "DISJUNCTION"
     IMPLICATION = "IMPLICATION"
     BICONDITIONAL = "BICONDITIONAL"
+    XOR = "XOR"
     LEFT_PAREN = "LEFT_PAREN"
     RIGHT_PAREN = "RIGHT_PAREN"
     EOF = "EOF"

evaluation_function/parsing/tokenizer.py

@@ -18,6 +18,7 @@ def _create_default_matchers(self) -> List[TokenMatcher]:
             SingleCharTokenMatcher("∨", TokenType.DISJUNCTION),
             SingleCharTokenMatcher("→", TokenType.IMPLICATION),
             SingleCharTokenMatcher("↔", TokenType.BICONDITIONAL),
+            SingleCharTokenMatcher("⊕", TokenType.XOR),
             SingleCharTokenMatcher("(", TokenType.LEFT_PAREN),
             SingleCharTokenMatcher(")", TokenType.RIGHT_PAREN),
             AtomTokenMatcher(),