Merge pull request #1523 from m-holger/oh_array

Refactor private API class Array

Merge pull request #1523 from m-holger/oh_array
Refactor private API class Array
m-holger · GitHub
2 parents db288584 e3ce9e17
Showing 8 changed files with 383 additions and 268 deletions
include/qpdf/ObjectHandle.hh
libqpdf/NNTree.cc
libqpdf/QPDFObjectHandle.cc
libqpdf/QPDF_Array.cc
libqpdf/QPDF_Stream.cc
libqpdf/qpdf/QPDFObjectHandle_private.hh
libtests/sparse_array.cc
qpdf/qpdf.testcov
@@ -74,7 +74,6 @@ namespace qpdf
         }
         QPDFObjectHandle operator[](size_t n) const;
-
         QPDFObjectHandle operator[](int n) const;
         std::shared_ptr<QPDFObject> copy(bool shallow = false) const;
@@ -104,11 +103,18 @@ namespace qpdf
         BaseHandle& operator=(BaseHandle const&) = default;
         BaseHandle(BaseHandle&&) = default;
         BaseHandle& operator=(BaseHandle&&) = default;
+
+        inline BaseHandle(QPDFObjectHandle const& oh);
+        inline BaseHandle(QPDFObjectHandle&& oh);
+
         ~BaseHandle() = default;
         template <typename T>
         T* as() const;
+        inline void assign(qpdf_object_type_e required, BaseHandle const& other);
+        inline void assign(qpdf_object_type_e required, BaseHandle&& other);
+
         std::string description() const;
         std::runtime_error type_error(char const* expected_type) const;
         QPDFExc type_error(char const* expected_type, std::string const& message) const;
@@ -11,6 +11,8 @@
 #include <exception>
 #include <utility>
+using namespace qpdf;
+
 static std::string
 get_description(QPDFObjectHandle const& node)
 {
@@ -66,7 +68,7 @@ NNTreeIterator::updateIValue(bool allow_invalid)
         ivalue.second = QPDFObjectHandle();
         return;
     }
-    auto items = node.getKey(impl.details.itemsKey());
+    Array items = node.getKey(impl.details.itemsKey());
     if (!std::cmp_less(item_number + 1, items.size())) {
         impl.error(node, "update ivalue: items array is too short");
     }
@@ -85,7 +87,7 @@ NNTreeIterator::getNextKid(PathElement&amp; pe, bool backward)
 {
     while (true) {
         pe.kid_number += backward ? -1 : 1;
-        auto kids = pe.node.getKey("/Kids");
+        Array kids = pe.node.getKey("/Kids");
         if (pe.kid_number >= 0 && std::cmp_less(pe.kid_number, kids.size())) {
             auto result = kids[pe.kid_number];
             if (result.isDictionary() &&
@@ -117,7 +119,7 @@ NNTreeIterator::increment(bool backward)
     while (valid()) {
         item_number += backward ? -2 : 2;
-        auto items = node.getKey(impl.details.itemsKey());
+        Array items = node.getKey(impl.details.itemsKey());
         if (item_number < 0 || std::cmp_greater_equal(item_number, items.size())) {
             bool found = false;
             setItemNumber(QPDFObjectHandle(), -1);
@@ -152,9 +154,9 @@ NNTreeIterator::resetLimits(QPDFObjectHandle a_node, std::list&lt;PathElement&gt;::ite
             a_node.removeKey("/Limits");
             break;
         }
-        auto kids = a_node.getKey("/Kids");
-        size_t nkids = kids.isArray() ? kids.size() : 0;
-        auto items = a_node.getKey(impl.details.itemsKey());
+        Array kids = a_node.getKey("/Kids");
+        size_t nkids = kids.size();
+        Array items = a_node.getKey(impl.details.itemsKey());
         size_t nitems = items.size();
         bool changed = true;
@@ -167,8 +169,8 @@ NNTreeIterator::resetLimits(QPDFObjectHandle a_node, std::list&lt;PathElement&gt;::ite
             auto first_kid = kids[0];
             auto last_kid = kids[nkids - 1u];
             if (first_kid.isDictionary() && last_kid.isDictionary()) {
-                auto first_limits = first_kid.getKey("/Limits");
-                auto last_limits = last_kid.getKey("/Limits");
+                Array first_limits = first_kid.getKey("/Limits");
+                Array last_limits = last_kid.getKey("/Limits");
                 if (first_limits.size() >= 2 && last_limits.size() >= 2) {
                     first = first_limits[0];
                     last = last_limits[1];
@@ -176,16 +178,14 @@ NNTreeIterator::resetLimits(QPDFObjectHandle a_node, std::list&lt;PathElement&gt;::ite
             }
         }
         if (first && last) {
-            auto limits = QPDFObjectHandle::newArray();
-            limits.appendItem(first);
-            limits.appendItem(last);
-            auto olimits = a_node.getKey("/Limits");
+            Array limits({first, last});
+            Array olimits = a_node.getKey("/Limits");
             if (olimits.size() == 2) {
                 auto ofirst = olimits[0];
                 auto olast = olimits[1];
                 if (impl.details.keyValid(ofirst) && impl.details.keyValid(olast) &&
-                    (impl.details.compareKeys(first, ofirst) == 0) &&
-                    (impl.details.compareKeys(last, olast) == 0)) {
+                    impl.details.compareKeys(first, ofirst) == 0 &&
+                    impl.details.compareKeys(last, olast) == 0) {
                     changed = false;
                 }
             }
@@ -240,24 +240,23 @@ NNTreeIterator::split(QPDFObjectHandle to_split, std::list&lt;PathElement&gt;::iterato
     }
     // Find the array we actually need to split, which is either this node's kids or items.
-    auto kids = to_split.getKey("/Kids");
-    int nkids = kids.isArray() ? static_cast<int>(kids.size()) : 0;
-    auto items = to_split.getKey(impl.details.itemsKey());
-    int nitems = items.isArray() ? static_cast<int>(items.size()) : 0;
+    Array kids = to_split.getKey("/Kids");
+    size_t nkids = kids.size();
+    Array items = to_split.getKey(impl.details.itemsKey());
+    size_t nitems = items.size();
-    QPDFObjectHandle first_half;
-    int n = 0;
+    Array first_half;
+    size_t n = 0;
     std::string key;
-    int threshold = 0;
+    size_t threshold = static_cast<size_t>(impl.split_threshold);
     if (nkids > 0) {
         first_half = kids;
         n = nkids;
-        threshold = impl.split_threshold;
         key = "/Kids";
     } else if (nitems > 0) {
         first_half = items;
         n = nitems;
-        threshold = 2 * impl.split_threshold;
+        threshold *= 2;
         key = impl.details.itemsKey();
     } else {
         throw std::logic_error("NNTreeIterator::split called on invalid node");
@@ -289,8 +288,8 @@ NNTreeIterator::split(QPDFObjectHandle to_split, std::list&lt;PathElement&gt;::iterato
         auto first_node = impl.qpdf.makeIndirectObject(QPDFObjectHandle::newDictionary());
         first_node.replaceKey(key, first_half);
-        QPDFObjectHandle new_kids = QPDFObjectHandle::newArray();
-        new_kids.appendItem(first_node);
+        Array new_kids;
+        new_kids.push_back(first_node);
         to_split.removeKey("/Limits"); // already shouldn't be there for root
         to_split.removeKey(impl.details.itemsKey());
         to_split.replaceKey("/Kids", new_kids);
@@ -310,11 +309,11 @@ NNTreeIterator::split(QPDFObjectHandle to_split, std::list&lt;PathElement&gt;::iterato
     // Create a second half array, and transfer the second half of the items into the second half
     // array.
-    QPDFObjectHandle second_half = QPDFObjectHandle::newArray();
-    int start_idx = ((n / 2) & ~1);
+    Array second_half;
+    auto start_idx = static_cast<int>((n / 2) & ~1u);
     while (std::cmp_greater(first_half.size(), start_idx)) {
-        second_half.appendItem(first_half[start_idx]);
-        first_half.eraseItem(start_idx);
+        second_half.push_back(first_half[start_idx]);
+        first_half.erase(start_idx);
     }
     resetLimits(to_split, parent);
@@ -331,8 +330,8 @@ NNTreeIterator::split(QPDFObjectHandle to_split, std::list&lt;PathElement&gt;::iterato
     // kid_number to traverse through it. We need to update to_split's path element, or the node if
     // this is a leaf, so that the kid/item number points to the right place.
-    auto parent_kids = parent->node.getKey("/Kids");
-    parent_kids.insertItem(parent->kid_number + 1, second_node);
+    Array parent_kids = parent->node.getKey("/Kids");
+    parent_kids.insert(parent->kid_number + 1, second_node);
     auto cur_elem = parent;
     ++cur_elem; // points to end() for leaf nodes
     int old_idx = (is_leaf ? item_number : cur_elem->kid_number);
@@ -367,22 +366,21 @@ void
 NNTreeIterator::insertAfter(QPDFObjectHandle const& key, QPDFObjectHandle const& value)
 {
     if (!valid()) {
-        QTC::TC("qpdf", "NNTree insertAfter inserts first");
         impl.insertFirst(key, value);
         deepen(impl.oh, true, false);
         return;
     }
-    auto items = node.getKey(impl.details.itemsKey());
+    Array items = node.getKey(impl.details.itemsKey());
+    if (!items) {
+        impl.error(node, "node contains no items array");
+    }
     if (std::cmp_less(items.size(), item_number + 2)) {
-        if (!items.isArray()) {
-            impl.error(node, "node contains no items array");
-        }
         impl.error(node, "insert: items array is too short");
     }
-    items.insertItem(item_number + 2, key);
-    items.insertItem(item_number + 3, value);
+    items.insert(item_number + 2, key);
+    items.insert(item_number + 3, value);
     resetLimits(node, lastPathElement());
     split(node, lastPathElement());
     increment(false);
@@ -396,14 +394,14 @@ NNTreeIterator::remove()
     if (!valid()) {
         throw std::logic_error("attempt made to remove an invalid iterator");
     }
-    auto items = node.getKey(impl.details.itemsKey());
+    Array items = node.getKey(impl.details.itemsKey());
     int nitems = static_cast<int>(items.size());
     if (std::cmp_greater(item_number + 2, nitems)) {
         impl.error(node, "found short items array while removing an item");
     }
-    items.eraseItem(item_number);
-    items.eraseItem(item_number);
+    items.erase(item_number);
+    items.erase(item_number);
     nitems -= 2;
     if (nitems > 0) {
@@ -443,8 +441,8 @@ NNTreeIterator::remove()
         auto element = lastPathElement();
         auto parent = element;
         --parent;
-        auto kids = element->node.getKey("/Kids");
-        kids.eraseItem(element->kid_number);
+        Array kids = element->node.getKey("/Kids");
+        kids.erase(element->kid_number);
         auto nkids = kids.size();
         if (nkids > 0) {
             // The logic here is similar to the items case.
@@ -462,7 +460,7 @@ NNTreeIterator::remove()
                 }
             } else {
                 // Next kid is in deleted kid's position
-                deepen(kids.getArrayItem(element->kid_number), true, true);
+                deepen(kids.get(element->kid_number), true, true);
             }
             return;
         }
@@ -470,7 +468,7 @@ NNTreeIterator::remove()
         if (parent == path.end()) {
             // We erased the very last item. Convert the root to an empty items array.
             element->node.removeKey("/Kids");
-            element->node.replaceKey(impl.details.itemsKey(), QPDFObjectHandle::newArray());
+            element->node.replaceKey(impl.details.itemsKey(), Array());
             path.clear();
             setItemNumber(impl.oh, -1);
             return;
@@ -527,10 +525,7 @@ NNTreeIterator::operator==(NNTreeIterator const&amp; other) const
         ++tpi;
         ++opi;
     }
-    if (item_number != other.item_number) {
-        return false;
-    }
-    return true;
+    return item_number == other.item_number;
 }
 void
@@ -574,27 +569,30 @@ NNTreeIterator::deepen(QPDFObjectHandle a_node, bool first, bool allow_empty)
             return fail(a_node, "non-dictionary node while traversing name/number tree");
         }
-        auto items = a_node.getKey(impl.details.itemsKey());
+        Array items = a_node.getKey(impl.details.itemsKey());
         int nitems = static_cast<int>(items.size());
         if (nitems > 1) {
             setItemNumber(a_node, first ? 0 : nitems - 2);
             break;
         }
-        auto kids = a_node.getKey("/Kids");
-        int nkids = kids.isArray() ? static_cast<int>(kids.size()) : 0;
+        Array kids = a_node.getKey("/Kids");
+        int nkids = static_cast<int>(kids.size());
         if (nkids > 0) {
             int kid_number = first ? 0 : nkids - 1;
             addPathElement(a_node, kid_number);
             auto next = kids[kid_number];
-            if (!next.isIndirect()) {
+            if (!next) {
+                return fail(a_node, "kid number " + std::to_string(kid_number) + " is invalid");
+            }
+            if (!next.indirect()) {
                 if (impl.auto_repair) {
                     impl.warn(
                         a_node,
                         "converting kid number " + std::to_string(kid_number) +
                             " to an indirect object");
                     next = impl.qpdf.makeIndirectObject(next);
-                    kids.setArrayItem(kid_number, next);
+                    kids.set(kid_number, next);
                 } else {
                     impl.warn(
                         a_node,
@@ -602,7 +600,7 @@ NNTreeIterator::deepen(QPDFObjectHandle a_node, bool first, bool allow_empty)
                 }
             }
             a_node = next;
-        } else if (allow_empty && items.isArray()) {
+        } else if (allow_empty && items) {
             setItemNumber(a_node, -1);
             break;
         } else {
@@ -655,8 +653,8 @@ NNTreeImpl::last()
 int
 NNTreeImpl::withinLimits(QPDFObjectHandle const& key, QPDFObjectHandle const& node)
 {
-    auto limits = node.getKey("/Limits");
-    if (!(limits.size() >= 2 && details.keyValid(limits[0]) && details.keyValid(limits[1]))) {
+    Array limits = node.getKey("/Limits");
+    if (!(details.keyValid(limits[0]) && details.keyValid(limits[1]))) {
         error(node, "node is missing /Limits");
     }
     if (details.compareKeys(key, limits[0]) < 0) {
@@ -734,7 +732,7 @@ void
 NNTreeImpl::repair()
 {
     auto new_node = QPDFObjectHandle::newDictionary();
-    new_node.replaceKey(details.itemsKey(), QPDFObjectHandle::newArray());
+    new_node.replaceKey(details.itemsKey(), Array());
     NNTreeImpl repl(details, qpdf, new_node, false);
     for (auto const& i: *this) {
         repl.insert(i.first, i.second);
@@ -750,7 +748,6 @@ NNTreeImpl::find(QPDFObjectHandle key, bool return_prev_if_not_found)
         return findInternal(key, return_prev_if_not_found);
     } catch (QPDFExc& e) {
         if (auto_repair) {
-            QTC::TC("qpdf", "NNTree repair");
             warn(oh, std::string("attempting to repair after error: ") + e.what());
             repair();
             return findInternal(key, return_prev_if_not_found);
@@ -784,7 +781,7 @@ NNTreeImpl::findInternal(QPDFObjectHandle const&amp; key, bool return_prev_if_not_fo
             error(node, "loop detected in find");
         }
-        auto items = node.getKey(details.itemsKey());
+        Array items = node.getKey(details.itemsKey());
         size_t nitems = items.size();
         if (nitems > 1) {
             int idx = binarySearch(
@@ -795,8 +792,8 @@ NNTreeImpl::findInternal(QPDFObjectHandle const&amp; key, bool return_prev_if_not_fo
             return result;
         }
-        auto kids = node.getKey("/Kids");
-        size_t nkids = kids.isArray() ? kids.size() : 0;
+        Array kids = node.getKey("/Kids");
+        size_t nkids = kids.size();
         if (nkids > 0) {
             int idx = binarySearch(key, kids, nkids, true, &NNTreeImpl::compareKeyKid);
             if (idx == -1) {
@@ -814,15 +811,15 @@ NNTreeImpl::iterator
 NNTreeImpl::insertFirst(QPDFObjectHandle const& key, QPDFObjectHandle const& value)
 {
     auto iter = begin();
-    QPDFObjectHandle items;
+    Array items(nullptr);
     if (iter.node.isDictionary()) {
         items = iter.node.getKey(details.itemsKey());
     }
-    if (!items.isArray()) {
+    if (!items) {
         error(oh, "unable to find a valid items node");
     }
-    items.insertItem(0, key);
-    items.insertItem(1, value);
+    items.insert(0, key);
+    items.insert(1, value);
     iter.setItemNumber(iter.node, 0);
     iter.resetLimits(iter.node, iter.lastPathElement());
     iter.split(iter.node, iter.lastPathElement());
@@ -836,8 +833,8 @@ NNTreeImpl::insert(QPDFObjectHandle const&amp; key, QPDFObjectHandle const&amp; value)
     if (!iter.valid()) {
         return insertFirst(key, value);
     } else if (details.compareKeys(key, iter->first) == 0) {
-        auto items = iter.node.getKey(details.itemsKey());
-        items.setArrayItem(iter.item_number + 1, value);
+        Array items = iter.node.getKey(details.itemsKey());
+        items.set(iter.item_number + 1, value);
         iter.updateIValue();
     } else {
         iter.insertAfter(key, value);
@@ -486,7 +486,7 @@ BaseHandle::write_json(int json_version, JSON::Writer&amp; p) const
             } else {
                 for (auto const& item: a.elements) {
                     p.writeNext();
-                    auto item_og = item.getObj()->getObjGen();
+                    auto item_og = item.id_gen();
                     if (item_og.isIndirect()) {
                         p << "\"" << item_og.unparse(' ') << " R\"";
                     } else {
@@ -1234,11 +1234,10 @@ QPDFObjectHandle::arrayOrStreamToStreamArray(
     if (auto array = as_array(strict)) {
         int n_items = static_cast<int>(array.size());
         for (int i = 0; i < n_items; ++i) {
-            QPDFObjectHandle item = array.at(i).second;
+            QPDFObjectHandle item = array[i];
             if (item.isStream()) {
                 result.emplace_back(item);
             } else {
-                QTC::TC("qpdf", "QPDFObjectHandle non-stream in stream array");
                 item.warn(
                     {qpdf_e_damaged_pdf,
                      "",
@@ -2,6 +2,7 @@
 #include <qpdf/QTC.hh>
+#include <array>
 #include <utility>
 using namespace std::literals;
@@ -60,6 +61,21 @@ Array::array() const
     return nullptr; // unreachable
 }
+Array::Array(bool empty) :
+    BaseHandle(empty ? QPDFObject::create<QPDF_Array>() : nullptr)
+{
+}
+
+Array::Array(std::vector<QPDFObjectHandle> const& items) :
+    BaseHandle(QPDFObject::create<QPDF_Array>(items))
+{
+}
+
+Array::Array(std::vector<QPDFObjectHandle>&& items) :
+    BaseHandle(QPDFObject::create<QPDF_Array>(std::move(items)))
+{
+}
+
 Array::iterator
 Array::begin()
 {
@@ -159,22 +175,58 @@ Array::null() const
 size_t
 Array::size() const
 {
-    auto a = array();
-    return a->sp ? a->sp->size : a->elements.size();
+    if (auto a = as<QPDF_Array>()) {
+        return a->sp ? a->sp->size : a->elements.size();
+    }
+    return 0;
 }
-std::pair<bool, QPDFObjectHandle>
-Array::at(int n) const
+QPDFObjectHandle const&
+Array::operator[](size_t n) const
 {
-    auto a = array();
-    if (n < 0 || std::cmp_greater_equal(n, size())) {
-        return {false, {}};
+    static const QPDFObjectHandle null_obj;
+    auto a = as<QPDF_Array>();
+    if (!a) {
+        return null_obj;
+    }
+    if (a->sp) {
+        auto const& iter = a->sp->elements.find(n);
+        return iter == a->sp->elements.end() ? null_obj : iter->second;
     }
+    return n >= a->elements.size() ? null_obj : a->elements[n];
+}
+
+QPDFObjectHandle const&
+Array::operator[](int n) const
+{
+    static const QPDFObjectHandle null_obj;
+    if (n < 0) {
+        return null_obj;
+    }
+    return (*this)[static_cast<size_t>(n)];
+}
+
+QPDFObjectHandle
+Array::get(size_t n) const
+{
+    if (n >= size()) {
+        return {};
+    }
+    auto a = array();
     if (!a->sp) {
-        return {true, a->elements[to_s(n)]};
+        return a->elements[n];
     }
-    auto const& iter = a->sp->elements.find(to_s(n));
-    return {true, iter == a->sp->elements.end() ? null() : iter->second};
+    auto const& iter = a->sp->elements.find(n);
+    return iter == a->sp->elements.end() ? null() : iter->second;
+}
+
+QPDFObjectHandle
+Array::get(int n) const
+{
+    if (n < 0) {
+        return {};
+    }
+    return get(to_s(n));
 }
 std::vector<QPDFObjectHandle>
@@ -196,21 +248,30 @@ Array::getAsVector() const
 }
 bool
-Array::setAt(int at, QPDFObjectHandle const& oh)
+Array::set(size_t at, QPDFObjectHandle const& oh)
 {
-    if (at < 0 || std::cmp_greater_equal(at, size())) {
+    if (at >= size()) {
         return false;
     }
     auto a = array();
     checkOwnership(oh);
     if (a->sp) {
-        a->sp->elements[to_s(at)] = oh;
+        a->sp->elements[at] = oh;
     } else {
-        a->elements[to_s(at)] = oh;
+        a->elements[at] = oh;
     }
     return true;
 }
+bool
+Array::set(int at, QPDFObjectHandle const& oh)
+{
+    if (at < 0) {
+        return false;
+    }
+    return set(to_s(at), oh);
+}
+
 void
 Array::setFromVector(std::vector<QPDFObjectHandle> const& v)
 {
@@ -224,43 +285,48 @@ Array::setFromVector(std::vector&lt;QPDFObjectHandle&gt; const&amp; v)
 }
 bool
-Array::insert(int at_i, QPDFObjectHandle const& item)
+Array::insert(size_t at, QPDFObjectHandle const& item)
 {
     auto a = array();
     size_t sz = size();
-    if (at_i < 0) {
-        return false;
-    }
-    size_t at = to_s(at_i);
     if (at > sz) {
         return false;
     }
+    checkOwnership(item);
     if (at == sz) {
         // As special case, also allow insert beyond the end
         push_back(item);
         return true;
     }
-    checkOwnership(item);
-    if (a->sp) {
-        auto iter = a->sp->elements.crbegin();
-        while (iter != a->sp->elements.crend()) {
-            auto key = (iter++)->first;
-            if (key >= at) {
-                auto nh = a->sp->elements.extract(key);
-                ++nh.key();
-                a->sp->elements.insert(std::move(nh));
-            } else {
-                break;
-            }
+    if (!a->sp) {
+        a->elements.insert(a->elements.cbegin() + to_i(at), item);
+        return true;
+    }
+    auto iter = a->sp->elements.crbegin();
+    while (iter != a->sp->elements.crend()) {
+        auto key = (iter++)->first;
+        if (key >= at) {
+            auto nh = a->sp->elements.extract(key);
+            ++nh.key();
+            a->sp->elements.insert(std::move(nh));
+        } else {
+            break;
         }
-        a->sp->elements[at] = item.getObj();
-        ++a->sp->size;
-    } else {
-        a->elements.insert(a->elements.cbegin() + at_i, item.getObj());
     }
+    a->sp->elements[at] = item;
+    ++a->sp->size;
     return true;
 }
+bool
+Array::insert(int at_i, QPDFObjectHandle const& item)
+{
+    if (at_i < 0) {
+        return false;
+    }
+    return insert(to_s(at_i), item);
+}
+
 void
 Array::push_back(QPDFObjectHandle const& item)
 {
@@ -274,61 +340,68 @@ Array::push_back(QPDFObjectHandle const&amp; item)
 }
 bool
-Array::erase(int at_i)
+Array::erase(size_t at)
 {
     auto a = array();
-    if (at_i < 0) {
-        return false;
-    }
-    size_t at = to_s(at_i);
     if (at >= size()) {
         return false;
     }
-    if (a->sp) {
-        auto end = a->sp->elements.end();
-        if (auto iter = a->sp->elements.lower_bound(at); iter != end) {
-            if (iter->first == at) {
-                iter++;
-                a->sp->elements.erase(at);
-            }
+    if (!a->sp) {
+        a->elements.erase(a->elements.cbegin() + to_i(at));
+        return true;
+    }
+    auto end = a->sp->elements.end();
+    if (auto iter = a->sp->elements.lower_bound(at); iter != end) {
+        if (iter->first == at) {
+            iter++;
+            a->sp->elements.erase(at);
+        }
-            while (iter != end) {
-                auto nh = a->sp->elements.extract(iter++);
-                --nh.key();
-                a->sp->elements.insert(std::move(nh));
-            }
+        while (iter != end) {
+            auto nh = a->sp->elements.extract(iter++);
+            --nh.key();
+            a->sp->elements.insert(std::move(nh));
         }
-        --(a->sp->size);
-    } else {
-        a->elements.erase(a->elements.cbegin() + at_i);
     }
+    --(a->sp->size);
     return true;
 }
+bool
+Array::erase(int at_i)
+{
+    if (at_i < 0) {
+        return false;
+    }
+    return erase(to_s(at_i));
+}
+
 int
 QPDFObjectHandle::getArrayNItems() const
 {
-    if (auto array = as_array(strict)) {
-        return to_i(array.size());
+    auto s = size();
+    if (s > 1 || isArray()) {
+        return to_i(s);
     }
     typeWarning("array", "treating as empty");
-    QTC::TC("qpdf", "QPDFObjectHandle array treating as empty");
     return 0;
 }
 QPDFObjectHandle
 QPDFObjectHandle::getArrayItem(int n) const
 {
-    if (auto array = as_array(strict)) {
-        if (auto const [success, oh] = array.at(n); success) {
-            return oh;
-        } else {
-            objectWarning("returning null for out of bounds array access");
-            QTC::TC("qpdf", "QPDFObjectHandle array bounds");
+    if (auto array = Array(*this)) {
+        if (auto result = array[n]) {
+            return result;
         }
+        if (n >= 0 && std::cmp_less(n, array.size())) {
+            // sparse array null
+            return newNull();
+        }
+        objectWarning("returning null for out of bounds array access");
+
     } else {
         typeWarning("array", "returning null");
-        QTC::TC("qpdf", "QPDFObjectHandle array null for non-array");
     }
     static auto constexpr msg = " -> null returned from invalid array access"sv;
     return QPDF_Null::create(obj, msg, "");
@@ -337,69 +410,61 @@ QPDFObjectHandle::getArrayItem(int n) const
 bool
 QPDFObjectHandle::isRectangle() const
 {
-    if (auto array = as_array(strict)) {
-        for (int i = 0; i < 4; ++i) {
-            if (auto item = array.at(i).second; !item.isNumber()) {
-                return false;
-            }
+    Array array(*this);
+    for (auto const& oh: array) {
+        if (!oh.isNumber()) {
+            return false;
         }
-        return array.size() == 4;
     }
-    return false;
+    return array.size() == 4;
 }
 bool
 QPDFObjectHandle::isMatrix() const
 {
-    if (auto array = as_array(strict)) {
-        for (int i = 0; i < 6; ++i) {
-            if (auto item = array.at(i).second; !item.isNumber()) {
-                return false;
-            }
+    Array array(*this);
+    for (auto const& oh: array) {
+        if (!oh.isNumber()) {
+            return false;
         }
-        return array.size() == 6;
     }
-    return false;
+    return array.size() == 6;
 }
 QPDFObjectHandle::Rectangle
 QPDFObjectHandle::getArrayAsRectangle() const
 {
-    if (auto array = as_array(strict)) {
-        if (array.size() != 4) {
+    Array array(*this);
+    if (array.size() != 4) {
+        return {};
+    }
+    std::array<double, 4> items;
+    for (size_t i = 0; i < 4; ++i) {
+        if (!array[i].getValueAsNumber(items[i])) {
             return {};
         }
-        double items[4];
-        for (int i = 0; i < 4; ++i) {
-            if (auto item = array.at(i).second; !item.getValueAsNumber(items[i])) {
-                return {};
-            }
-        }
-        return {
-            std::min(items[0], items[2]),
-            std::min(items[1], items[3]),
-            std::max(items[0], items[2]),
-            std::max(items[1], items[3])};
     }
-    return {};
+    return {
+        std::min(items[0], items[2]),
+        std::min(items[1], items[3]),
+        std::max(items[0], items[2]),
+        std::max(items[1], items[3])};
 }
 QPDFObjectHandle::Matrix
 QPDFObjectHandle::getArrayAsMatrix() const
 {
-    if (auto array = as_array(strict)) {
-        if (array.size() != 6) {
+    Array array(*this);
+    if (array.size() != 6) {
+        return {};
+    }
+    std::array<double, 6> items;
+    for (size_t i = 0; i < 6; ++i) {
+        if (!array[i].getValueAsNumber(items[i])) {
             return {};
         }
-        double items[6];
-        for (int i = 0; i < 6; ++i) {
-            if (auto item = array.at(i).second; !item.getValueAsNumber(items[i])) {
-                return {};
-            }
-        }
-        return {items[0], items[1], items[2], items[3], items[4], items[5]};
     }
-    return {};
+    return {items[0], items[1], items[2], items[3], items[4], items[5]};
 }
 std::vector<QPDFObjectHandle>
@@ -417,13 +482,11 @@ void
 QPDFObjectHandle::setArrayItem(int n, QPDFObjectHandle const& item)
 {
     if (auto array = as_array(strict)) {
-        if (!array.setAt(n, item)) {
+        if (!array.set(n, item)) {
             objectWarning("ignoring attempt to set out of bounds array item");
-            QTC::TC("qpdf", "QPDFObjectHandle set array bounds");
         }
     } else {
         typeWarning("array", "ignoring attempt to set item");
-        QTC::TC("qpdf", "QPDFObjectHandle array ignoring set item");
     }
 }
 void
@@ -493,11 +556,9 @@ QPDFObjectHandle::eraseItem(int at)
 QPDFObjectHandle
 QPDFObjectHandle::eraseItemAndGetOld(int at)
 {
-    auto array = as_array(strict);
-    auto result =
-        (array && std::cmp_less(at, array.size()) && at >= 0) ? array.at(at).second : newNull();
+    auto result = Array(*this)[at];
     eraseItem(at);
-    return result;
+    return result ? result : newNull();
 }
 size_t
@@ -532,36 +593,13 @@ BaseHandle::size() const
 QPDFObjectHandle
 BaseHandle::operator[](size_t n) const
 {
-    switch (resolved_type_code()) {
-    case ::ot_array:
-        {
-            auto a = as<QPDF_Array>();
-            if (n >= a->size()) {
-                return {};
-            }
-            return Array(obj).at(static_cast<int>(n)).second;
-        }
-    case ::ot_uninitialized:
-    case ::ot_reserved:
-    case ::ot_null:
-    case ::ot_destroyed:
-    case ::ot_unresolved:
-    case ::ot_reference:
-        return {};
-    case ::ot_boolean:
-    case ::ot_integer:
-    case ::ot_real:
-    case ::ot_string:
-    case ::ot_name:
-    case ::ot_dictionary:
-    case ::ot_stream:
-    case ::ot_inlineimage:
-    case ::ot_operator:
-        return {obj};
-    default:
-        throw std::logic_error("Unexpected type code in size"); // unreachable
-        return {};                                              // unreachable
+    if (resolved_type_code() == ::ot_array) {
+        return Array(obj)[n];
     }
+    if (n < size()) {
+        return *this;
+    }
+    return {};
 }
 QPDFObjectHandle
@@ -442,7 +442,7 @@ Stream::filterable(
         int i = -1;
         for (auto& filter: filters) {
-            auto d_obj = decode_array.at(++i).second;
+            auto d_obj = decode_array.get(++i);
             if (!can_filter(decode_level, *filter, d_obj)) {
                 return false;
             }
@@ -12,6 +12,30 @@ namespace qpdf
     class Array final: public BaseHandle
     {
       public:
+        // Create an empty Array. If 'empty' is false, create a null Array.
+        Array(bool empty = true);
+
+        Array(std::vector<QPDFObjectHandle> const& items);
+
+        Array(std::vector<QPDFObjectHandle>&& items);
+
+        Array(Array const& other) :
+            BaseHandle(other.obj)
+        {
+        }
+
+        Array&
+        operator=(Array const& other)
+        {
+            if (obj != other.obj) {
+                obj = other.obj;
+            }
+            return *this;
+        }
+
+        Array(Array&&) = default;
+        Array& operator=(Array&&) = default;
+
         explicit Array(std::shared_ptr<QPDFObject> const& obj) :
             BaseHandle(obj)
         {
@@ -22,6 +46,34 @@ namespace qpdf
         {
         }
+        Array(QPDFObjectHandle const& oh) :
+            BaseHandle(oh.resolved_type_code() == ::ot_array ? oh : QPDFObjectHandle())
+        {
+        }
+
+        Array&
+        operator=(QPDFObjectHandle const& oh)
+        {
+            assign(::ot_array, oh);
+            return *this;
+        }
+
+        Array(QPDFObjectHandle&& oh) :
+            BaseHandle(oh.resolved_type_code() == ::ot_array ? std::move(oh) : QPDFObjectHandle())
+        {
+        }
+
+        Array&
+        operator=(QPDFObjectHandle&& oh)
+        {
+            assign(::ot_array, std::move(oh));
+            return *this;
+        }
+
+        QPDFObjectHandle const& operator[](size_t n) const;
+
+        QPDFObjectHandle const& operator[](int n) const;
+
         using iterator = std::vector<QPDFObjectHandle>::iterator;
         using const_iterator = std::vector<QPDFObjectHandle>::const_iterator;
         using const_reverse_iterator = std::vector<QPDFObjectHandle>::const_reverse_iterator;
@@ -38,11 +90,16 @@ namespace qpdf
         const_reverse_iterator crend();
+        // Return the number of elements in the array. Return 0 if the object is not an array.
         size_t size() const;
-        std::pair<bool, QPDFObjectHandle> at(int n) const;
-        bool setAt(int at, QPDFObjectHandle const& oh);
+        QPDFObjectHandle get(size_t n) const;
+        QPDFObjectHandle get(int n) const;
+        bool set(size_t at, QPDFObjectHandle const& oh);
+        bool set(int at, QPDFObjectHandle const& oh);
+        bool insert(size_t at, QPDFObjectHandle const& item);
         bool insert(int at, QPDFObjectHandle const& item);
         void push_back(QPDFObjectHandle const& item);
+        bool erase(size_t at);
         bool erase(int at);
         std::vector<QPDFObjectHandle> getAsVector() const;
@@ -342,6 +399,32 @@ namespace qpdf
         return nullptr;
     }
+    inline BaseHandle::BaseHandle(QPDFObjectHandle const& oh) :
+        obj(oh.obj)
+    {
+    }
+
+    inline BaseHandle::BaseHandle(QPDFObjectHandle&& oh) :
+        obj(std::move(oh.obj))
+    {
+    }
+
+    inline void
+    BaseHandle::assign(qpdf_object_type_e required, BaseHandle const& other)
+    {
+        if (obj != other.obj) {
+            obj = other.resolved_type_code() == required ? other.obj : nullptr;
+        }
+    }
+
+    inline void
+    BaseHandle::assign(qpdf_object_type_e required, BaseHandle&& other)
+    {
+        if (obj != other.obj) {
+            obj = other.resolved_type_code() == required ? std::move(other.obj) : nullptr;
+        }
+    }
+
     inline QPDFObjGen
     BaseHandle::id_gen() const
     {
@@ -26,69 +26,69 @@ main()
     a.push_back(QPDFObjectHandle::parse("null"));
     a.push_back(QPDFObjectHandle::parse("/Quack"));
     assert(a.size() == 5);
-    assert(a.at(0).second.isInteger() && (a.at(0).second.getIntValue() == 1));
-    assert(a.at(1).second.isString() && (a.at(1).second.getStringValue() == "potato"));
-    assert(a.at(2).second.isNull());
-    assert(a.at(3).second.isNull());
-    assert(a.at(4).second.isName() && (a.at(4).second.getName() == "/Quack"));
+    assert(a[0].isInteger() && (a[0].getIntValue() == 1));
+    assert(a[1].isString() && (a[1].getStringValue() == "potato"));
+    assert(a[2].isNull());
+    assert(a[3].isNull());
+    assert(a[4].isName() && (a[4].getName() == "/Quack"));
     a.insert(4, QPDFObjectHandle::parse("/BeforeQuack"));
     assert(a.size() == 6);
-    assert(a.at(0).second.isInteger() && (a.at(0).second.getIntValue() == 1));
-    assert(a.at(4).second.isName() && (a.at(4).second.getName() == "/BeforeQuack"));
-    assert(a.at(5).second.isName() && (a.at(5).second.getName() == "/Quack"));
+    assert(a[0].isInteger() && (a[0].getIntValue() == 1));
+    assert(a[4].isName() && (a[4].getName() == "/BeforeQuack"));
+    assert(a[5].isName() && (a[5].getName() == "/Quack"));
     a.insert(2, QPDFObjectHandle::parse("/Third"));
     assert(a.size() == 7);
-    assert(a.at(1).second.isString() && (a.at(1).second.getStringValue() == "potato"));
-    assert(a.at(2).second.isName() && (a.at(2).second.getName() == "/Third"));
-    assert(a.at(3).second.isNull());
-    assert(a.at(6).second.isName() && (a.at(6).second.getName() == "/Quack"));
+    assert(a[1].isString() && (a[1].getStringValue() == "potato"));
+    assert(a[2].isName() && (a[2].getName() == "/Third"));
+    assert(a[3].isNull());
+    assert(a[6].isName() && (a[6].getName() == "/Quack"));
     a.insert(0, QPDFObjectHandle::parse("/First"));
     assert(a.size() == 8);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(7).second.isName() && (a.at(7).second.getName() == "/Quack"));
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[7].isName() && (a[7].getName() == "/Quack"));
     a.erase(6);
     assert(a.size() == 7);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(5).second.isNull());
-    assert(a.at(6).second.isName() && (a.at(6).second.getName() == "/Quack"));
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[5].isNull());
+    assert(a[6].isName() && (a[6].getName() == "/Quack"));
     a.erase(6);
     assert(a.size() == 6);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(3).second.isName() && (a.at(3).second.getName() == "/Third"));
-    assert(a.at(4).second.isNull());
-    assert(a.at(5).second.isNull());
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[3].isName() && (a[3].getName() == "/Third"));
+    assert(a[4].isNull());
+    assert(a[5].isNull());
-    a.setAt(4, QPDFObjectHandle::parse("12"));
-    assert(a.at(4).second.isInteger() && (a.at(4).second.getIntValue() == 12));
-    a.setAt(4, QPDFObjectHandle::newNull());
-    assert(a.at(4).second.isNull());
+    a.set(4, QPDFObjectHandle::parse("12"));
+    assert(a[4].isInteger() && (a[4].getIntValue() == 12));
+    a.set(4, QPDFObjectHandle::newNull());
+    assert(a[4].isNull());
     a.erase(to_i(a.size()) - 1);
     assert(a.size() == 5);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(3).second.isName() && (a.at(3).second.getName() == "/Third"));
-    assert(a.at(4).second.isNull());
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[3].isName() && (a[3].getName() == "/Third"));
+    assert(a[4].isNull());
     a.erase(to_i(a.size()) - 1);
     assert(a.size() == 4);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(3).second.isName() && (a.at(3).second.getName() == "/Third"));
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[3].isName() && (a[3].getName() == "/Third"));
     a.erase(to_i(a.size()) - 1);
     assert(a.size() == 3);
-    assert(a.at(0).second.isName() && (a.at(0).second.getName() == "/First"));
-    assert(a.at(1).second.isInteger() && (a.at(1).second.getIntValue() == 1));
-    assert(a.at(2).second.isString() && (a.at(2).second.getStringValue() == "potato"));
+    assert(a[0].isName() && (a[0].getName() == "/First"));
+    assert(a[1].isInteger() && (a[1].getIntValue() == 1));
+    assert(a[2].isString() && (a[2].getStringValue() == "potato"));
     QPDF pdf;
     pdf.emptyPDF();
@@ -96,22 +96,22 @@ main()
     obj = QPDFObject::create<QPDF_Array>(
         std::vector<QPDFObjectHandle>{10, "null"_qpdf.getObj()}, true);
     auto b = qpdf::Array(obj);
-    b.setAt(5, pdf.newIndirectNull());
-    b.setAt(7, "[0 1 2 3]"_qpdf);
-    assert(b.at(3).second.isNull());
-    assert(b.at(8).second.isNull());
-    assert(b.at(5).second.isIndirect());
+    b.set(5, pdf.newIndirectNull());
+    b.set(7, "[0 1 2 3]"_qpdf);
+    assert(b[3].null());
+    assert(b[8].null());
+    assert(b[5].indirect());
     assert(
         QPDFObjectHandle(obj).unparse() ==
         "[ null null null null null 3 0 R null [ 0 1 2 3 ] null null ]");
     auto c = QPDFObjectHandle(obj).unsafeShallowCopy();
     auto d = QPDFObjectHandle(obj).shallowCopy();
-    b.at(7).second.setArrayItem(2, "42"_qpdf);
+    b.get(7).setArrayItem(2, "42"_qpdf);
     assert(c.unparse() == "[ null null null null null 3 0 R null [ 0 1 42 3 ] null null ]");
     assert(d.unparse() == "[ null null null null null 3 0 R null [ 0 1 2 3 ] null null ]");
     try {
-        b.setAt(3, {});
+        b.set(3, {});
         std::cout << "inserted uninitialized object\n";
     } catch (std::logic_error&) {
     }
@@ -119,7 +119,7 @@ main()
     pdf2.emptyPDF();
     try {
         pdf.makeIndirectObject(obj);
-        b.setAt(3, pdf2.getObject(1, 0));
+        b.set(3, pdf2.getObject(1, 0));
         std::cout << "inserted uninitialized object\n";
     } catch (std::logic_error&) {
     }
@@ -282,7 +282,6 @@ qpdf-c called qpdf_set_newline_before_endstream 0
 SF_FlateLzwDecode TIFF predictor 0
 QPDFTokenizer inline image at EOF 0
 Pl_QPDFTokenizer found ID 0
-QPDFObjectHandle non-stream in stream array 0
 QPDFObjectHandle coalesce called on stream 0
 QPDFObjectHandle coalesce provide stream data 0
 QPDF_Stream bad token at end during normalize 0
@@ -290,7 +289,6 @@ QPDFParser bad token in parse 0
 QPDFParser bad token in parseRemainder 0
 QPDFParser eof in parse 0
 QPDFParser eof in parseRemainder 0
-QPDFObjectHandle array bounds 0
 QPDFObjectHandle boolean returning false 0
 QPDFObjectHandle integer returning 0 0
 QPDFObjectHandle real returning 0.0 0
@@ -299,11 +297,7 @@ QPDFObjectHandle string returning empty string 0
 QPDFObjectHandle string returning empty utf8 0
 QPDFObjectHandle operator returning fake value 0
 QPDFObjectHandle inlineimage returning empty data 0
-QPDFObjectHandle array treating as empty 0
-QPDFObjectHandle array null for non-array 0
 QPDFObjectHandle array treating as empty vector 0
-QPDFObjectHandle array ignoring set item 0
-QPDFObjectHandle set array bounds 0
 QPDFObjectHandle array ignoring replace items 0
 QPDFObjectHandle array ignoring insert item 0
 QPDFObjectHandle insert array bounds 0
@@ -519,8 +513,6 @@ qpdf-c called qpdf_oh_unparse_resolved 0
 qpdf-c called qpdf_oh_unparse_binary 0
 QPDFWriter getFilterOnWrite false 0
 QPDFPageObjectHelper::forEachXObject 3
-NNTree repair 0
-NNTree insertAfter inserts first 0
 NNTree erased last kid/item in tree 1
 QPDFPageObjectHelper unresolved names 0
 QPDFPageObjectHelper resolving unresolved 0