PS: Add unary expression AST class.

Author: MathiasVP

powershell/ql/lib/powershell.qll

@@ -22,6 +22,7 @@ import semmle.code.powershell.ScriptBlock
 import semmle.code.powershell.StringLiteral
 import semmle.code.powershell.AssignmentStatement
 import semmle.code.powershell.BinaryExpression
+import semmle.code.powershell.UnaryExpression
 import semmle.code.powershell.ScriptBlockExpr
 import semmle.code.powershell.TernaryExpression
 import semmle.code.powershell.UsingExpression

powershell/ql/lib/semmle/code/powershell/UnaryExpression.qll

@@ -0,0 +1,15 @@
+import powershell
+
+class UnaryExpr extends @unary_expression, Expr {
+  override SourceLocation getLocation() { unary_expression_location(this, result) }
+
+  int getKind() { unary_expression(this, _, result, _) }
+
+  Expr getOperand() { unary_expression(this, result, _, _) }
+}
+
+class NotExpr extends UnaryExpr {
+  NotExpr() { this.getKind() = 36 }
+
+  final override string toString() { result = "!..." }
+}