Add PDFVersion class

ChangeLog

@@ -1,3 +1,8 @@
+2022-02-08  Jay Berkenbilt  <ejb@ql.org>
+
+	* Add new class PDFVersion for more convenient comparison of PDF
+	version numbers from the %!PDF header.
+
 2022-02-06  Jay Berkenbilt  <ejb@ql.org>
 
 	* Pl_Buffer and QPDFWriter: add getBufferSharedPointer(), which

include/qpdf/PDFVersion.hh

@@ -0,0 +1,73 @@
+// 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.
+
+// This class implements a simple writer for saving QPDF objects to
+// new PDF files.  See comments through the header file for additional
+// details.
+
+#ifndef PDFVERSION_HH
+#define PDFVERSION_HH
+
+#include <qpdf/DLL.h>
+#include <string>
+
+class PDFVersion
+{
+  public:
+    // Represent a PDF version. PDF versions are typically
+    // major.minor, but PDF 1.7 has several extension levels as the
+    // ISO 32000 spec was in progress. This class helps with
+    // comparison of versions.
+    QPDF_DLL
+    PDFVersion();
+    QPDF_DLL
+    PDFVersion(PDFVersion const&) = default;
+    QPDF_DLL
+    PDFVersion(int major, int minor, int extension = 0);
+    QPDF_DLL
+    bool operator<(PDFVersion const& rhs) const;
+    QPDF_DLL
+    bool operator==(PDFVersion const& rhs) const;
+
+    // Replace this version with the other one if the other one is
+    // greater.
+    QPDF_DLL
+    void updateIfGreater(PDFVersion const& other);
+
+    // Initialize a string and integer suitable for passing to
+    // QPDFWriter::setMinimumPDFVersion or QPDFWriter::forcePDFVersion.
+    QPDF_DLL
+    void getVersion(std::string& version, int& extension_level) const;
+
+    QPDF_DLL
+    int getMajor() const;
+    QPDF_DLL
+    int getMinor() const;
+    QPDF_DLL
+    int getExtensionLevel() const;
+
+  private:
+    int major;
+    int minor;
+    int extension;
+};
+
+#endif // PDFVERSION_HH

libqpdf/PDFVersion.cc

@@ -0,0 +1,69 @@
+#include <qpdf/PDFVersion.hh>
+
+#include <qpdf/QUtil.hh>
+
+PDFVersion::PDFVersion() :
+    PDFVersion(0, 0, 0)
+{
+}
+
+PDFVersion::PDFVersion(int major, int minor, int extension) :
+    major(major),
+    minor(minor),
+    extension(extension)
+{
+}
+
+bool
+PDFVersion::operator<(PDFVersion const& rhs) const
+{
+    return ((this->major < rhs.major) ? true :
+            (this->major > rhs.major) ? false :
+            (this->minor < rhs.minor) ? true :
+            (this->minor > rhs.minor) ? false :
+            (this->extension < rhs.minor) ? true :
+            false);
+}
+
+bool
+PDFVersion::operator==(PDFVersion const& rhs) const
+{
+    return ((this->major == rhs.major) &&
+            (this->minor == rhs.minor) &&
+            (this->extension == rhs.extension));
+}
+
+void
+PDFVersion::updateIfGreater(PDFVersion const& other)
+{
+    if (*this < other)
+    {
+        *this = other;
+    }
+}
+
+void
+PDFVersion::getVersion(std::string& version, int& extension_level) const
+{
+    extension_level = this->extension;
+    version = QUtil::int_to_string(this->major) + "." +
+        QUtil::int_to_string(this->minor);
+}
+
+int
+PDFVersion::getMajor() const
+{
+    return this->major;
+}
+
+int
+PDFVersion::getMinor() const
+{
+    return this->minor;
+}
+
+int
+PDFVersion::getExtensionLevel() const
+{
+    return this->extension;
+}

libqpdf/build.mk

@@ -42,6 +42,7 @@ SRCS_libqpdf = \
 	libqpdf/MD5.cc \
 	libqpdf/NNTree.cc \
 	libqpdf/OffsetInputSource.cc \
+	libqpdf/PDFVersion.cc \
 	libqpdf/Pipeline.cc \
 	libqpdf/Pl_AES_PDF.cc \
 	libqpdf/Pl_ASCII85Decoder.cc \

libtests/build.mk

@@ -21,6 +21,7 @@ BINS_libtests = \
 	md5 \
 	nntree \
 	numrange \
+	pdf_version \
 	pointer_holder \
 	predictors \
 	qintc \

libtests/pdf_version.cc

@@ -0,0 +1,39 @@
+#include <qpdf/PDFVersion.hh>
+
+#include <cassert>
+#include <iostream>
+
+int main()
+{
+    PDFVersion v1;
+    assert(v1.getMajor() == 0);
+    assert(v1.getMinor() == 0);
+    assert(v1.getExtensionLevel() == 0);
+    v1 = PDFVersion(1, 7, 8);
+    assert(v1.getMajor() == 1);
+    assert(v1.getMinor() == 7);
+    assert(v1.getExtensionLevel() == 8);
+    std::string version;
+    int extension_level = -1;
+    v1.getVersion(version, extension_level);
+    assert(version == "1.7");
+    assert(extension_level == 8);
+    PDFVersion v2(1, 5);
+    v2.getVersion(version, extension_level);
+    assert(version == "1.5");
+    assert(extension_level == 0);
+    assert(v2 < v1);
+    PDFVersion v3 = v1;
+    assert(v3 == v1);
+    v1.updateIfGreater(v2);
+    assert(v3 == v1);
+    assert(! (v3 == v2));
+    assert(! (v2 == v1));
+    v2.updateIfGreater(v1);
+    assert(v2 == v1);
+    v2.getVersion(version, extension_level);
+    assert(version == "1.7");
+    assert(extension_level == 8);
+    std::cout << "PDFVersion assertions passed" << std::endl;
+    return 0;
+}

libtests/qtest/version.test

@@ -0,0 +1,16 @@
+#!/usr/bin/env perl
+require 5.008;
+use warnings;
+use strict;
+
+require TestDriver;
+
+my $td = new TestDriver('pdf_version');
+
+$td->runtest("pdf_version",
+             {$td->COMMAND => "pdf_version"},
+             {$td->STRING => "PDFVersion assertions passed\n",
+                  $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+
+$td->report(1);