Add new Pl_OStream Pipeline

ChangeLog

@@ -1,5 +1,8 @@
 2022-05-03  Jay Berkenbilt  <ejb@ql.org>
 
+        * Add new Pipeline class Pl_OStream, similar to Pl_StdioFile but
+        takes a std::ostream instead of a FILE*.
+
         * Add new convenience methods to Pipeline: writeCStr and
         writeString. Also add a limit << operator that takes C strings and
         std::strings. Also add an overloaded version of write that takes

TODO

@@ -47,7 +47,6 @@ Output JSON v2
 notes from 5/2:
 
 Need new pipelines:
-* Pl_OStream(std::ostream) with semantics like Pl_StdioFile
 * Pl_String to std::string with semantics like Pl_Buffer
 
 See if I can change all output and error messages issued by the

include/qpdf/Pl_OStream.hh

@@ -0,0 +1,69 @@
+// Copyright (c) 2005-2022 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.
+
+// End-of-line pipeline that simply writes its data to a stdio FILE* object.
+
+#ifndef PL_OSTREAM_HH
+#define PL_OSTREAM_HH
+
+#include <qpdf/Pipeline.hh>
+
+#include <iostream>
+
+//
+// This pipeline is reusable.
+//
+
+class QPDF_DLL_CLASS Pl_OStream: public Pipeline
+{
+  public:
+    // os is externally maintained; this class just writes to and
+    // flushes it.  It does not close it.
+    QPDF_DLL
+    Pl_OStream(char const* identifier, std::ostream& os);
+    QPDF_DLL
+    virtual ~Pl_OStream();
+
+    QPDF_DLL
+    virtual void write(unsigned char const* buf, size_t len);
+    QPDF_DLL
+    virtual void finish();
+
+  private:
+    class QPDF_DLL_PRIVATE Members
+    {
+        friend class Pl_OStream;
+
+      public:
+        QPDF_DLL
+        ~Members() = default;
+
+      private:
+        Members(std::ostream&);
+        Members(Members const&) = delete;
+
+        std::ostream& os;
+    };
+
+    std::shared_ptr<Members> m;
+};
+
+#endif // PL_OSTREAM_HH

libqpdf/CMakeLists.txt

@@ -44,6 +44,7 @@ set(libqpdf_SOURCES
   Pl_Flate.cc
   Pl_LZWDecoder.cc
   Pl_MD5.cc
+  Pl_OStream.cc
   Pl_PNGFilter.cc
   Pl_QPDFTokenizer.cc
   Pl_RC4.cc

libqpdf/Pl_OStream.cc

@@ -0,0 +1,35 @@
+#include <qpdf/Pl_OStream.hh>
+
+#include <qpdf/QUtil.hh>
+#include <errno.h>
+#include <stdexcept>
+
+Pl_OStream::Members::Members(std::ostream& os) :
+    os(os)
+{
+}
+
+Pl_OStream::Pl_OStream(char const* identifier, std::ostream& os) :
+    Pipeline(identifier, 0),
+    m(new Members(os))
+{
+}
+
+Pl_OStream::~Pl_OStream()
+{
+    // Must be explicit and not inline -- see QPDF_DLL_CLASS in
+    // README-maintainer
+}
+
+void
+Pl_OStream::write(unsigned char const* buf, size_t len)
+{
+    this->m->os.write(
+        reinterpret_cast<char const*>(buf), static_cast<std::streamsize>(len));
+}
+
+void
+Pl_OStream::finish()
+{
+    this->m->os.flush();
+}

libtests/base64.cc

@@ -2,7 +2,7 @@
 
 #include <qpdf/Pl_Base64.hh>
 
-#include <qpdf/Pl_StdioFile.hh>
+#include <qpdf/Pl_OStream.hh>
 #include <qpdf/QUtil.hh>
 #include <cstdlib>
 #include <cstring>
@@ -52,7 +52,7 @@ main(int argc, char* argv[])
     }
 
     try {
-        Pl_StdioFile out("stdout", stdout);
+        Pl_OStream out("stdout", std::cout);
         Pl_Base64 decode("decode", &out, action);
         // The comments are "n: n%4 n%3", where n is the number of
         // bytes read at the end of the call, and are there to

manual/release-notes.rst

@@ -117,6 +117,9 @@ For a detailed list of changes, please see the file
 
       - ``operator <<``: for null-terminated C strings and std::strings
 
+    - Add new ``Pipeline`` type ``Pl_OStream`` to write to a
+      ``std::ostream``.
+
   - Other changes
 
     - A new chapter on contributing to qpdf has been added to the

qpdf/sizes.cc

@@ -16,6 +16,7 @@
 #include <qpdf/Pl_DCT.hh>
 #include <qpdf/Pl_Discard.hh>
 #include <qpdf/Pl_Flate.hh>
+#include <qpdf/Pl_OStream.hh>
 #include <qpdf/Pl_QPDFTokenizer.hh>
 #include <qpdf/Pl_RunLength.hh>
 #include <qpdf/Pl_StdioFile.hh>
@@ -75,6 +76,7 @@ main()
     print_size(Pl_DCT);
     print_size(Pl_Discard);
     print_size(Pl_Flate);
+    print_size(Pl_OStream);
     print_size(Pl_QPDFTokenizer);
     print_size(Pl_RunLength);
     print_size(Pl_StdioFile);