cpdf_numbertree.h

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// Copyright 2016 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
#ifndef CORE_FPDFDOC_CPDF_NUMBERTREE_H_
#define CORE_FPDFDOC_CPDF_NUMBERTREE_H_
 
#include <optional>
 
#include "core/fxcrt/retain_ptr.h"
 
class CPDF_Dictionary;
class CPDF_Object;
 
// Represents a number tree that allows for sub-linear lookups of tree nodes.
// See ISO 32000-1:2008 spec, section 7.9.7.
class CPDF_NumberTree {
 public:
  struct KeyValue {
    KeyValue(int key, RetainPtr<const CPDF_Object> value);
    KeyValue(const KeyValue&) = delete;
    KeyValue& operator=(const KeyValue&) = delete;
    KeyValue(KeyValue&&) noexcept;
    KeyValue& operator=(KeyValue&&) noexcept;
    ~KeyValue();
 
    int key;
    RetainPtr<const CPDF_Object> value;
  };
 
  explicit CPDF_NumberTree(RetainPtr<const CPDF_Dictionary> root);
  ~CPDF_NumberTree();
 
  // Finds the object in the number tree whose key is `num`. Returns nullptr in
  // there is no `num` key in the tree.
  RetainPtr<const CPDF_Object> LookupValue(int num) const;
 
  // Finds the object in the number tree with the largest key, such that
  // `num` >= key. Returns the key/value pair if such a key exists, or
  // std::nullopt otherwise.
  // Note that this is similar to, but not exactly the same as
  // std::lower_bound().
  std::optional<KeyValue> GetLowerBound(int num) const;
 
 protected:
  RetainPtr<const CPDF_Dictionary> const root_;
};
 
#endif  // CORE_FPDFDOC_CPDF_NUMBERTREE_H_