// Copyright (c) 2005-2021 Jay Berkenbilt

// Copyright (c) 2022-2026 Jay Berkenbilt and Manfred Holger

//

// 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 PIPELINE_HH

#define PIPELINE_HH

#include <qpdf/DLL.h>

#include <memory>

#include <string>

// 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.

//

// 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);

    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);

    Pipeline*

    next() const noexcept

    {

        return next_;

    }

    std::string identifier;

  private:

    Pipeline(Pipeline const&) = delete;

    Pipeline& operator=(Pipeline const&) = delete;

    Pipeline* next_;

};

#endif // PIPELINE_HH