Rust: Add helper predicates for accessing statements and expressions together.

rust/ql/lib/codeql/rust/elements/internal/StmtListImpl.qll

@@ -1,4 +1,3 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `StmtList`.
  *
@@ -26,5 +25,25 @@ module Impl {
    * //  ^^^^^^^^^
    * ```
    */
-  class StmtList extends Generated::StmtList { }
+  class StmtList extends Generated::StmtList {
+    /**
+     * Gets the `index`th statement or expression of this statement list (0-based).
+     */
+    AstNode getStmtOrExpr(int index) {
+      result = this.getStatement(index)
+      or
+      index = max(int i | exists(this.getStatement(i))) + 1 and
+      result = this.getTailExpr()
+    }
+
+    /**
+     * Gets any of the statements or expressions of this statement list.
+     */
+    final AstNode getAStmtOrExpr() { result = this.getStmtOrExpr(_) }
+
+    /**
+     * Gets the number of statements or expressions of this statement list.
+     */
+    final int getNumberOfStmtOrExpr() { result = count(int i | exists(this.getStmtOrExpr(i))) }
+  }
 }