Add QPDFNumberTreeObjectHelper

1 files changed, 110 insertions, 0 deletions

diff --git a/include/qpdf/QPDFNumberTreeObjectHelper.hh b/include/qpdf/QPDFNumberTreeObjectHelper.hh
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+++ b/include/qpdf/QPDFNumberTreeObjectHelper.hh
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+// Copyright (c) 2005-2018 Jay Berkenbilt
+//
+// This file is part of qpdf.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Versions of qpdf prior to version 7 were released under the terms
+// of version 2.0 of the Artistic License. At your option, you may
+// continue to consider qpdf to be licensed under those terms. Please
+// see the manual for additional information.
+
+#ifndef QPDFNUMBERTREEOBJECTHELPER_HH
+#define QPDFNUMBERTREEOBJECTHELPER_HH
+
+#include <qpdf/QPDFObjectHelper.hh>
+#include <qpdf/QPDFObjGen.hh>
+#include <functional>
+#include <map>
+
+#include <qpdf/DLL.h>
+
+// This is an object helper for number trees. See section 7.9.7 in the
+// PDF spec (ISO 32000) for a description of number trees. This
+// implementation disregards stated limits and sequencing and simply
+// builds a map from numerical index to object. If the array of
+// numbers does not contain a numerical value where expected, this
+// implementation silently skips forward until it finds a number.
+
+class QPDFNumberTreeObjectHelper: public QPDFObjectHelper
+{
+  public:
+    QPDF_DLL
+    QPDFNumberTreeObjectHelper(QPDFObjectHandle);
+
+    typedef long long int numtree_number;
+
+    // Return overall minimum and maximum indices
+    QPDF_DLL
+    numtree_number getMin();
+    QPDF_DLL
+    numtree_number getMax();
+
+    // Return whether the number tree has an explicit entry for this
+    // number.
+    QPDF_DLL
+    bool hasIndex(numtree_number idx);
+
+    // Find an object with a specific index. If found, returns true
+    // and initializes oh.
+    QPDF_DLL
+    bool findObject(numtree_number idx, QPDFObjectHandle& oh);
+    // Find the object at the index or, if not found, the object whose
+    // index is the highest index less than the requested index. If
+    // the requested index is less than the minimum, return false.
+    // Otherwise, return true, initialize oh to the object, and set
+    // offset to the difference between the requested index and the
+    // actual index. For example, if a number tree has values for 3
+    // and 6 and idx is 5, this method would return true, initialize
+    // oh to the value with index 3, and set offset to 2 (5 - 3).
+    QPDF_DLL
+    bool findObjectAtOrBelow(numtree_number idx, QPDFObjectHandle& oh,
+                             numtree_number& offset);
+
+    typedef std::map<numtree_number, QPDFObjectHandle> idx_map;
+    QPDF_DLL
+    idx_map getAsMap() const;
+
+  private:
+    class Members
+    {
+        friend class QPDFNumberTreeObjectHelper;
+        typedef QPDFNumberTreeObjectHelper::numtree_number numtree_number;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+
+        // Use a reverse sorted map so we can use the lower_bound
+        // method for searching. lower_bound returns smallest entry
+        // not before the searched entry, meaning that the searched
+        // entry is the lower bound. There's also an upper_bound
+        // method, but it does not do what you'd think it should.
+        // lower_bound implements >=, and upper_bound implements >.
+        typedef std::map<numtree_number,
+                         QPDFObjectHandle,
+                         std::greater<numtree_number> > idx_map;
+        idx_map entries;
+        std::set<QPDFObjGen> seen;
+    };
+
+    void updateMap(QPDFObjectHandle oh);
+
+    PointerHolder<Members> m;
+};
+
+#endif // QPDFNUMBERTREEOBJECTHELPER_HH