Tune handling of sparse arrays in QPDF_Array

Sparse arrays are rare. Dynamically create the variables needed to manage
them only when needed.

1 files changed, 9 insertions, 4 deletions

diff --git a/libqpdf/qpdf/QPDF_Array.hh b/libqpdf/qpdf/QPDF_Array.hh
index 10ac9f8c..281e1d48 100644
--- a/libqpdf/qpdf/QPDF_Array.hh
+++ b/libqpdf/qpdf/QPDF_Array.hh
@@ -8,6 +8,13 @@
 
 class QPDF_Array: public QPDFValue
 {
+  private:
+    struct Sparse
+    {
+        int size{0};
+        std::map<int, std::shared_ptr<QPDFObject>> elements;
+    };
+
   public:
     ~QPDF_Array() override = default;
     static std::shared_ptr<QPDFObject> create(std::vector<QPDFObjectHandle> const& items);
@@ -21,7 +28,7 @@ class QPDF_Array: public QPDFValue
     int
     size() const noexcept
     {
-        return sparse ? sp_size : int(elements.size());
+        return sp ? sp->size : int(elements.size());
     }
     QPDFObjectHandle at(int n) const noexcept;
     bool setAt(int n, QPDFObjectHandle const& oh);
@@ -39,9 +46,7 @@ class QPDF_Array: public QPDFValue
 
     void checkOwnership(QPDFObjectHandle const& item) const;
 
-    bool sparse{false};
-    int sp_size{0};
-    std::map<int, std::shared_ptr<QPDFObject>> sp_elements;
+    std::unique_ptr<Sparse> sp;
     std::vector<std::shared_ptr<QPDFObject>> elements;
 };