Unified: Add more logical expressions to AstExtra.

Author: aschackmull

unified/ql/lib/codeql/unified/internal/AstExtra.qll

@@ -5,13 +5,26 @@
 private import unified
 
 module Public {
-  /**
-   * A logical 'and' expression with short-circuiting.
-   */
+  /** A short-circuiting logical AND expression. */
   class LogicalAndExpr extends BinaryExpr {
     LogicalAndExpr() { this.getOperator().getValue() = "&&" }
   }
 
+  /** A short-circuiting logical OR expression. */
+  class LogicalOrExpr extends BinaryExpr {
+    LogicalOrExpr() { this.getOperator().getValue() = "||" }
+  }
+
+  /** A short-circuiting null-coalescing expression. */
+  class NullCoalescingExpr extends BinaryExpr {
+    NullCoalescingExpr() { this.getOperator().getValue() = "??" }
+  }
+
+  /** A logical NOT expression. */
+  class LogicalNotExpr extends UnaryExpr {
+    LogicalNotExpr() { this.getOperator().(PrefixOperator).getValue() = "!" }
+  }
+
   /**
    * Declaration of a local or top-level variable.
    */