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// Copyright (c) 2005-2023 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.
// Generalized Pipeline interface. By convention, subclasses of Pipeline are called Pl_Something.
//
// When an instance of Pipeline is created with a pointer to a next pipeline, that pipeline writes
// its data to the next one when it finishes with it. In order to make possible a usage style in
// which a pipeline may be passed to a function which may stick other pipelines in front of it, the
// allocator of a pipeline is responsible for its destruction. In other words, one pipeline object
// does not attempt to manage the memory of its successor.
//
// The client is required to call finish() before destroying a Pipeline in order to avoid loss of
// data. A Pipeline class should not throw an exception in the destructor if this hasn't been done
// though since doing so causes too much trouble when deleting pipelines during error conditions.
//
// Some pipelines are reusable (i.e., you can call write() after calling finish() and can call
// finish() multiple times) while others are not. It is up to the caller to use a pipeline
// according to its own restrictions.
#ifndef PIPELINE_HH
#define PIPELINE_HH
#include <qpdf/DLL.h>
#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
#include <memory>
#include <string>
// Remember to use QPDF_DLL_CLASS on anything derived from Pipeline so it will work with
// dynamic_cast across the shared object boundary.
class QPDF_DLL_CLASS Pipeline
{
public:
QPDF_DLL
Pipeline(char const* identifier, Pipeline* next);
QPDF_DLL
virtual ~Pipeline() = default;
// Subclasses should implement write and finish to do their jobs and then, if they are not
// end-of-line pipelines, call getNext()->write or getNext()->finish.
QPDF_DLL
virtual void write(unsigned char const* data, size_t len) = 0;
QPDF_DLL
virtual void finish() = 0;
QPDF_DLL
std::string getIdentifier() const;
// These are convenience methods for making it easier to write certain other types of data to
// pipelines without having to cast. The methods that take char const* expect null-terminated C
// strings and do not write the null terminators.
QPDF_DLL
void writeCStr(char const* cstr);
QPDF_DLL
void writeString(std::string const&);
// This allows *p << "x" << "y" but is not intended to be a general purpose << compatible with
// ostream and does not have local awareness or the ability to be "imbued" with properties.
QPDF_DLL
Pipeline& operator<<(char const* cstr);
QPDF_DLL
Pipeline& operator<<(std::string const&);
QPDF_DLL
Pipeline& operator<<(short);
QPDF_DLL
Pipeline& operator<<(int);
QPDF_DLL
Pipeline& operator<<(long);
QPDF_DLL
Pipeline& operator<<(long long);
QPDF_DLL
Pipeline& operator<<(unsigned short);
QPDF_DLL
Pipeline& operator<<(unsigned int);
QPDF_DLL
Pipeline& operator<<(unsigned long);
QPDF_DLL
Pipeline& operator<<(unsigned long long);
// Overloaded write to reduce casting
QPDF_DLL
void write(char const* data, size_t len);
protected:
QPDF_DLL
Pipeline* getNext(bool allow_null = false);
std::string identifier;
private:
Pipeline(Pipeline const&) = delete;
Pipeline& operator=(Pipeline const&) = delete;
Pipeline* next;
};
#endif // PIPELINE_HH
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