ExpressionParser: Add XOR operator.

Source/Core/DolphinQt/Config/Mapping/IOWindow.cpp

@@ -234,6 +234,7 @@ void IOWindow::CreateMainLayout()
     m_operators_combo->addItem(tr("> Greater-than"));
     m_operators_combo->addItem(tr("< Less-than"));
     m_operators_combo->addItem(tr("& And"));
+    m_operators_combo->addItem(tr("^ Xor"));
   }
   m_operators_combo->addItem(tr("| Or"));
   if (m_type == Type::Input)

Source/Core/InputCommon/ControlReference/ExpressionParser.cpp

@@ -136,6 +136,8 @@ Token Lexer::NextToken()
     return Token(TOK_GTHAN);
   case ',':
     return Token(TOK_COMMA);
+  case '^':
+    return Token(TOK_XOR);
   case '\'':
     return GetDelimitedLiteral();
   case '$':
@@ -278,6 +280,12 @@ public:
       lhs->GetValue();
       return rhs->GetValue();
     }
+    case TOK_XOR:
+    {
+      const auto lval = lhs->GetValue();
+      const auto rval = rhs->GetValue();
+      return std::max(std::min(1 - lval, rval), std::min(lval, 1 - rval));
+    }
     default:
       assert(false);
       return 0;
@@ -621,12 +629,14 @@ private:
       return 3;
     case TOK_AND:
       return 4;
-    case TOK_OR:
+    case TOK_XOR:
       return 5;
-    case TOK_ASSIGN:
+    case TOK_OR:
       return 6;
-    case TOK_COMMA:
+    case TOK_ASSIGN:
       return 7;
+    case TOK_COMMA:
+      return 8;
     default:
       assert(false);
       return 0;

Source/Core/InputCommon/ControlReference/ExpressionParser.h

@@ -39,6 +39,7 @@ enum TokenType
   TOK_LTHAN,
   TOK_GTHAN,
   TOK_COMMA,
+  TOK_XOR,
   TOK_BINARY_OPS_END,
 };