Add and test QPDFLogger class

1 files changed, 158 insertions, 0 deletions

diff --git a/include/qpdf/QPDFLogger.hh b/include/qpdf/QPDFLogger.hh
new file mode 100644
index 00000000..340706c9
--- /dev/null
+++ b/include/qpdf/QPDFLogger.hh
@@ -0,0 +1,158 @@
+// 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.
+
+#ifndef QPDFLOGGER_HH
+#define QPDFLOGGER_HH
+
+#include <qpdf/DLL.h>
+#include <qpdf/Pipeline.hh>
+#include <iostream>
+#include <memory>
+
+class QPDFLogger
+{
+  public:
+    QPDF_DLL
+    QPDFLogger();
+
+    QPDF_DLL
+    static std::shared_ptr<QPDFLogger> defaultLogger();
+
+    // Defaults:
+    //
+    // info -- if save is standard output, standard error, else standard output
+    // warn -- whatever error points to
+    // error -- standard error
+    // save -- undefined unless set
+    //
+    // On deletion, finish() is called for the standard output and
+    // standard error pipelines, which flushes output. If you supply
+    // any custom pipelines, you must call finish() on them yourself.
+    // Note that calling finish is not needed for string, stdio, or
+    // ostream pipelines.
+    //
+    // NOTES ABOUT THE SAVE PIPELINE
+    //
+    // You should never set the save pipeline to the same destination
+    // as something else. Doing so will corrupt your save output. If
+    // you want to save to standard output, use the method
+    // saveToStandardOutput(). In addition to setting the save
+    // pipeline, that does the following extra things:
+    //
+    // * If standard output has been used, a logic error is thrown
+    // * If info is set to standard output at the time of the set save
+    //   call, it is switched to standard error.
+    //
+    // This is not a guarantee. You can still mess this up in ways
+    // that are not checked. Here are a few examples:
+    //
+    // * Don't set any pipeline to standard output *after* passing it
+    //   to setSave()
+    // * Don't use a separate mechanism to write stdout/stderr other
+    //   than QPDFLogger::standardOutput()
+    // * Don't set anything to the same custom pipeline that save is
+    //   set to.
+    //
+    // Just be sure that if you change pipelines around, you should
+    // avoid having the save pipeline also be used for any other
+    // purpose. The special case for saving to standard output allows
+    // you to call saveToStandardOutput() early without having to
+    // worry about the info pipeline.
+
+    QPDF_DLL
+    void info(char const*);
+    QPDF_DLL
+    void info(std::string const&);
+    QPDF_DLL
+    std::shared_ptr<Pipeline> getInfo(bool null_okay = false);
+
+    QPDF_DLL
+    void warn(char const*);
+    QPDF_DLL
+    void warn(std::string const&);
+    QPDF_DLL
+    std::shared_ptr<Pipeline> getWarn(bool null_okay = false);
+
+    QPDF_DLL
+    void error(char const*);
+    QPDF_DLL
+    void error(std::string const&);
+    QPDF_DLL
+    std::shared_ptr<Pipeline> getError(bool null_okay = false);
+
+    QPDF_DLL
+    std::shared_ptr<Pipeline> getSave(bool null_okay = false);
+
+    QPDF_DLL
+    std::shared_ptr<Pipeline> standardOutput();
+    QPDF_DLL
+    std::shared_ptr<Pipeline> standardError();
+    QPDF_DLL
+    std::shared_ptr<Pipeline> discard();
+
+    // Passing a null pointer resets to default
+    QPDF_DLL
+    void setInfo(std::shared_ptr<Pipeline>);
+    QPDF_DLL
+    void setWarn(std::shared_ptr<Pipeline>);
+    QPDF_DLL
+    void setError(std::shared_ptr<Pipeline>);
+    // See notes above about the save pipeline
+    QPDF_DLL
+    void setSave(std::shared_ptr<Pipeline>);
+    QPDF_DLL
+    void saveToStandardOutput();
+
+    // Shortcut for logic to reset output to new output/error streams.
+    // out_stream is used for info, err_stream is used for error, and
+    // warning is cleared so that it follows error.
+    QPDF_DLL
+    void setOutputStreams(std::ostream* out_stream, std::ostream* err_stream);
+
+  private:
+    std::shared_ptr<Pipeline>
+    throwIfNull(std::shared_ptr<Pipeline>, bool null_okay);
+
+    class Members
+    {
+        friend class QPDFLogger;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&) = delete;
+
+        std::shared_ptr<Pipeline> p_discard;
+        std::shared_ptr<Pipeline> p_real_stdout;
+        std::shared_ptr<Pipeline> p_stdout;
+        std::shared_ptr<Pipeline> p_stderr;
+        std::shared_ptr<Pipeline> p_info;
+        std::shared_ptr<Pipeline> p_warn;
+        std::shared_ptr<Pipeline> p_error;
+        std::shared_ptr<Pipeline> p_save;
+    };
+    std::shared_ptr<Members> m;
+};
+
+#endif // QPDFLOGGER_HH