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https://github.com/qpdf/qpdf.git
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161 lines
4.0 KiB
C++
161 lines
4.0 KiB
C++
// Copyright (c) 2005-2023 Jay Berkenbilt
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//
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// This file is part of qpdf.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Versions of qpdf prior to version 7 were released under the terms
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// of version 2.0 of the Artistic License. At your option, you may
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// continue to consider qpdf to be licensed under those terms. Please
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// see the manual for additional information.
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#ifndef QPDFOBJGEN_HH
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#define QPDFOBJGEN_HH
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#include <qpdf/DLL.h>
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#include <iostream>
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#include <set>
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class QPDFObjectHandle;
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class QPDFObjectHelper;
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// This class represents an object ID and generation pair. It is
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// suitable to use as a key in a map or set.
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class QPDFObjGen
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{
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public:
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// ABI: change to default.
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QPDF_DLL
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QPDFObjGen() :
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obj(0),
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gen(0)
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{
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}
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QPDF_DLL
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explicit QPDFObjGen(int obj, int gen) :
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obj(obj),
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gen(gen)
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{
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}
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QPDF_DLL
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bool
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operator<(QPDFObjGen const& rhs) const
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{
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return (obj < rhs.obj) || ((obj == rhs.obj) && (gen < rhs.gen));
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}
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QPDF_DLL
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bool
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operator==(QPDFObjGen const& rhs) const
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{
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return (obj == rhs.obj) && (gen == rhs.gen);
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}
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QPDF_DLL
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bool
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operator!=(QPDFObjGen const& rhs) const
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{
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return (obj != rhs.obj) || (gen != rhs.gen);
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}
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QPDF_DLL
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int
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getObj() const
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{
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return obj;
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}
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QPDF_DLL
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int
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getGen() const
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{
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return gen;
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}
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QPDF_DLL
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bool
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isIndirect() const
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{
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return obj != 0;
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}
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QPDF_DLL
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std::string unparse(char separator = ',') const;
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QPDF_DLL
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friend std::ostream& operator<<(std::ostream& os, const QPDFObjGen& og);
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// Convenience class for loop detection when processing objects.
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//
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// The class adds 'add' methods to a std::set<QPDFObjGen> which allows
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// to test whether an QPDFObjGen is present in the set and to insert it in
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// a single operation. The 'add' method is overloaded to take a QPDFObjGen,
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// QPDFObjectHandle or an QPDFObjectHelper as parameter.
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//
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// The erase method is modified to ignore requests to erase
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// QPDFObjGen(0, 0).
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//
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// Usage example:
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//
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// void process_object(QPDFObjectHandle oh, QPDFObjGen::set& seen)
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// {
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// if (seen.add(oh)) {
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// // handle first encounter of oh
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// } else {
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// // handle loop / subsequent encounter of oh
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// }
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// }
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class QPDF_DLL_CLASS set: public std::set<QPDFObjGen>
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{
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public:
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// Add 'og' to the set. Return false if 'og' is already present in
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// the set. Attempts to insert QPDFObjGen(0, 0) are ignored.
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QPDF_DLL
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bool
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add(QPDFObjGen og)
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{
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if (og.isIndirect()) {
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if (count(og) > 0) {
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return false;
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}
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emplace(og);
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}
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return true;
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}
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QPDF_DLL
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bool add(QPDFObjectHandle const& oh);
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QPDF_DLL
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bool add(QPDFObjectHelper const& oh);
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QPDF_DLL
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void
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erase(QPDFObjGen og)
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{
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if (og.isIndirect()) {
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std::set<QPDFObjGen>::erase(og);
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}
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}
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QPDF_DLL
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void erase(QPDFObjectHandle const& oh);
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QPDF_DLL
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void erase(QPDFObjectHelper const& oh);
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};
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private:
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// This class does not use the Members pattern to avoid a memory
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// allocation for every one of these. A lot of these get created
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// and destroyed.
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int obj{0};
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int gen{0};
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};
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#endif // QPDFOBJGEN_HH
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