Refactor FormField class: replace inheritance from QPDFObjectHelper with BaseDic…

…tionary, modernize constructors, and clean up null handling logic.

Refactor FormField class: replace inheritance from QPDFObjectHelper with BaseDic…
…tionary, modernize constructors, and clean up null handling logic.
m-holger
1 parent 6ad83cfd
Showing 2 changed files with 22 additions and 19 deletions
libqpdf/QPDFFormFieldObjectHelper.cc
libqpdf/qpdf/FormField.hh
@@ -18,7 +18,7 @@ using namespace qpdf;
 using FormField = qpdf::impl::FormField;
-class QPDFFormFieldObjectHelper::Members: public qpdf::impl::FormField
+class QPDFFormFieldObjectHelper::Members: public FormField
 {
   public:
     Members(QPDFObjectHandle const& oh) :
@@ -34,44 +34,41 @@ QPDFFormFieldObjectHelper::QPDFFormFieldObjectHelper(QPDFObjectHandle o) :
 }
 QPDFFormFieldObjectHelper::QPDFFormFieldObjectHelper() :
-    QPDFObjectHelper(QPDFObjectHandle::newNull()),
-    m(std::make_shared<Members>(oh()))
+    QPDFObjectHelper(Null::temp()),
+    m(std::make_shared<Members>(QPDFObjectHandle()))
 {
 }
 bool
 QPDFFormFieldObjectHelper::isNull()
 {
-    return m->isNull();
-}
-
-bool
-FormField::isNull()
-{
-    return oh().null();
+    return m->null();
 }
 QPDFFormFieldObjectHelper
 QPDFFormFieldObjectHelper::getParent()
 {
-    return {m->getParent()};
+    return {Null::if_null(m->getParent().oh())};
 }
 FormField
 FormField::getParent()
 {
-    return oh().getKey("/Parent"); // may be null
+    return {oh()["/Parent"]}; // maybe null
 }
 QPDFFormFieldObjectHelper
 QPDFFormFieldObjectHelper::getTopLevelField(bool* is_different)
 {
-    return {m->getTopLevelField(is_different)};
+    return Null::if_null(m->getTopLevelField(is_different).oh());
 }
 FormField
 FormField::getTopLevelField(bool* is_different)
 {
+    if (!obj) {
+        return {};
+    }
     auto top_field = oh();
     QPDFObjGen::set seen;
     while (seen.add(top_field) && !top_field.getKeyIfDict("/Parent").null()) {
@@ -12,19 +12,25 @@ namespace qpdf::impl
 {
     // This object helper helps with form fields for interactive forms. Please see comments in
     // QPDFAcroFormDocumentHelper.hh for additional details.
-    class FormField: public QPDFObjectHelper
+    class FormField: public qpdf::BaseDictionary
     {
       public:
-        FormField() = delete;
+        FormField() = default;
+        FormField(FormField const&) = default;
+        FormField& operator=(FormField const&) = default;
+        FormField(FormField&&) = default;
+        FormField& operator=(FormField&&) = default;
+        ~FormField() = default;
         FormField(QPDFObjectHandle const& oh) :
-            QPDFObjectHelper(oh)
+            BaseDictionary(oh)
         {
         }
-        ~FormField() override = default;
-
-        bool isNull();
+        FormField(QPDFObjectHandle&& oh) :
+            BaseDictionary(std::move(oh))
+        {
+        }
         // Return the field's parent. A form field object helper whose underlying object is null is
         // returned if there is no parent. This condition may be tested by calling isNull().