Change type of QPDFValue::object_description to std::shared_ptr<std::variant>

Also, name the type QPDFValue::Description.

libqpdf/QPDFObjectHandle.cc

@@ -2176,7 +2176,8 @@ QPDFObjectHandle::setObjectDescription(
     // This is called during parsing on newly created direct objects,
     // so we can't call dereference() here.
     if (isInitialized() && obj.get()) {
-        auto descr = std::make_shared<std::string>(object_description);
+        auto descr =
+            std::make_shared<QPDFValue::Description>(object_description);
         obj->setDescription(owning_qpdf, descr);
     }
 }

libqpdf/QPDFValue.cc

@@ -13,16 +13,28 @@ QPDFValue::do_create(QPDFValue* object)
 std::string
 QPDFValue::getDescription()
 {
-    auto description = object_description ? *object_description : "";
+    if (object_description) {
-    if (auto pos = description.find("$OG"); pos != std::string::npos) {
+        switch (object_description->index()) {
-        description.replace(pos, 3, og.unparse(' '));
+        case 0:
-    }
+            {
-    if (auto pos = description.find("$PO"); pos != std::string::npos) {
+                auto description = std::get<0>(*object_description);
-        qpdf_offset_t shift = (type_code == ::ot_dictionary) ? 2
-            : (type_code == ::ot_array)                      ? 1
-                                                             : 0;
 
-        description.replace(pos, 3, std::to_string(parsed_offset + shift));
+                if (auto pos = description.find("$OG");
+                    pos != std::string::npos) {
+                    description.replace(pos, 3, og.unparse(' '));
+                }
+                if (auto pos = description.find("$PO");
+                    pos != std::string::npos) {
+                    qpdf_offset_t shift = (type_code == ::ot_dictionary) ? 2
+                        : (type_code == ::ot_array)                      ? 1
+                                                                         : 0;
+
+                    description.replace(
+                        pos, 3, std::to_string(parsed_offset + shift));
+                }
+                return description;
+            }
+        }
     }
-    return description;
+    return {};
 }

libqpdf/QPDF_Stream.cc

@@ -123,7 +123,7 @@ QPDF_Stream::QPDF_Stream(
         throw std::logic_error("stream object instantiated with non-dictionary "
                                "object for dictionary");
     }
-    auto descr = std::make_shared<std::string>(
+    auto descr = std::make_shared<QPDFValue::Description>(
         qpdf->getFilename() + ", stream object " + og.unparse(' '));
     setDescription(qpdf, descr, offset);
 }
@@ -283,7 +283,9 @@ QPDF_Stream::getStreamJSON(
 
 void
 QPDF_Stream::setDescription(
-    QPDF* qpdf, std::shared_ptr<std::string>& description, qpdf_offset_t offset)
+    QPDF* qpdf,
+    std::shared_ptr<QPDFValue::Description>& description,
+    qpdf_offset_t offset)
 {
     this->QPDFValue::setDescription(qpdf, description, offset);
     setDictDescription();

libqpdf/qpdf/QPDFObject_private.hh

@@ -71,7 +71,7 @@ class QPDFObject
     void
     setDescription(
         QPDF* qpdf,
-        std::shared_ptr<std::string>& description,
+        std::shared_ptr<QPDFValue::Description>& description,
         qpdf_offset_t offset = -1)
     {
         return value->setDescription(qpdf, description, offset);

libqpdf/qpdf/QPDFParser.hh

@@ -2,6 +2,7 @@
 #define QPDFPARSER_HH
 
 #include <qpdf/QPDFObjectHandle.hh>
+#include <qpdf/QPDFValue.hh>
 
 #include <memory>
 #include <string>
@@ -21,8 +22,8 @@ class QPDFParser
         tokenizer(tokenizer),
         decrypter(decrypter),
         context(context),
-        description(std::make_shared<std::string>(
+        description(std::make_shared<QPDFValue::Description>(std::string(
-            input->getName() + ", " + object_description + " at offset $PO"))
+            input->getName() + ", " + object_description + " at offset $PO")))
     {
     }
     virtual ~QPDFParser() = default;
@@ -49,7 +50,7 @@ class QPDFParser
     QPDFTokenizer& tokenizer;
     QPDFObjectHandle::StringDecrypter* decrypter;
     QPDF* context;
-    std::shared_ptr<std::string> description;
+    std::shared_ptr<QPDFValue::Description> description;
 };
 
 #endif // QPDFPARSER_HH

libqpdf/qpdf/QPDFValue.hh

@@ -8,6 +8,7 @@
 #include <qpdf/Types.h>
 
 #include <string>
+#include <variant>
 
 class QPDF;
 class QPDFObjectHandle;
@@ -23,10 +24,13 @@ class QPDFValue
     virtual std::shared_ptr<QPDFObject> copy(bool shallow = false) = 0;
     virtual std::string unparse() = 0;
     virtual JSON getJSON(int json_version) = 0;
+
+    using Description = std::variant<std::string>;
+
     virtual void
     setDescription(
         QPDF* qpdf_p,
-        std::shared_ptr<std::string>& description,
+        std::shared_ptr<Description>& description,
         qpdf_offset_t offset)
     {
         qpdf = qpdf_p;
@@ -37,7 +41,7 @@ class QPDFValue
     setDefaultDescription(QPDF* a_qpdf, QPDFObjGen const& a_og)
     {
         static auto default_description{
-            std::make_shared<std::string>("object $OG")};
+            std::make_shared<Description>("object $OG")};
         if (!object_description) {
             object_description = default_description;
         }
@@ -49,7 +53,7 @@ class QPDFValue
     hasDescription()
     {
         return qpdf != nullptr && object_description &&
-            !object_description->empty();
+            !getDescription().empty();
     }
     void
     setParsedOffset(qpdf_offset_t offset)
@@ -108,7 +112,7 @@ class QPDFValue
   private:
     QPDFValue(QPDFValue const&) = delete;
     QPDFValue& operator=(QPDFValue const&) = delete;
-    std::shared_ptr<std::string> object_description;
+    std::shared_ptr<Description> object_description;
 
     const qpdf_object_type_e type_code{::ot_uninitialized};
     char const* type_name{"uninitialized"};

libqpdf/qpdf/QPDF_Stream.hh

@@ -27,7 +27,9 @@ class QPDF_Stream: public QPDFValue
     virtual std::string unparse();
     virtual JSON getJSON(int json_version);
     virtual void setDescription(
-        QPDF*, std::shared_ptr<std::string>& description, qpdf_offset_t offset);
+        QPDF*,
+        std::shared_ptr<QPDFValue::Description>& description,
+        qpdf_offset_t offset);
     virtual void disconnect();
     QPDFObjectHandle getDict() const;
     bool isDataModified() const;