feat(jet): add ExprPtrs for pointer slice expressions

ExprPtrs dereferences []*T values, skips nil entries, and maps survivors
through a converter.

Co-authored-by: Cursor <cursoragent@cursor.com>

jet_expr.go

@@ -16,6 +16,19 @@ func ExprValues[T any](values []T, f func(T) Expression) []Expression {
 	return expressions
 }
 
+// ExprPtrs converts a list of pointers to Expression values, skipping nil
+// entries. Function f receives the dereferenced value.
+func ExprPtrs[T any](values []*T, f func(T) Expression) []Expression {
+	expressions := make([]Expression, 0, len(values))
+	for _, v := range values {
+		if v == nil {
+			continue
+		}
+		expressions = append(expressions, f(*v))
+	}
+	return expressions
+}
+
 // ExprStringers converts a list of fmt.Stringers to a list of Expression values.
 func ExprStringers(values []fmt.Stringer) []Expression {
 	expressions := make([]Expression, len(values))