Add operator ""_qpdf for creating QPDFObjectHandle literals

Jay Berkenbilt
1 parent b48a0ff0
Showing 14 changed files with 57 additions and 48 deletions
ChangeLog
TODO
examples/pdf-attach-file.cc
examples/pdf-create.cc
examples/pdf-overlay-page.cc
include/qpdf/QPDFObjectHandle.hh
libqpdf/QPDFFormFieldObjectHelper.cc
libqpdf/QPDFJob.cc
libqpdf/QPDFNameTreeObjectHelper.cc
libqpdf/QPDFNumberTreeObjectHelper.cc
libqpdf/QPDFObjectHandle.cc
libqpdf/QPDFPageDocumentHelper.cc
libqpdf/QPDFPageObjectHelper.cc
qpdf/test_driver.cc
 2022-02-05  Jay Berkenbilt  <ejb@ql.org>
  
+	* Add a global user-defined string literal "_qpdf" as a shorthand
+	for QPDFObjectHandle::parse, allowing you to create
+	QPDFObjectHandle objects with
+
+	QPDFObjectHandle oh = "<</Some (PDF)>>"_qpdf;
+
 	* Expose QPDF::emptyPDF to the C API as qpdf_empty_pdf()
  
 	* Add comments letting people know that the version string
@@ -11,9 +11,6 @@
  
 * QPDFObjectHandle: getValueAsX methods, getKeyIfDict. Plus C API.
  
-* Add user-defined initializer `QPDFObjectHandle operator ""_qpdf` to
-  be like QPDFObjectHandle::parse: `auto oh = "<< /a (b) >>"_qpdf;`
-
 * See if this has been done or is trivial with C++11 local static
   initializers: Secure random number generation could be made more
   efficient by using a local static to ensure a single random device
@@ -36,16 +36,16 @@ static void process(char const* infilename, char const* password,
     QPDF q;
     q.processFile(infilename, password);
  
-    // Create an indirect object for the built-in Helvetica font.
+    // Create an indirect object for the built-in Helvetica font. This
+    // uses the qpdf literal syntax introduced in qpdf 10.6.
     auto f1 = q.makeIndirectObject(
-        QPDFObjectHandle::parse(
-            "<<"
-            "  /Type /Font"
-            "  /Subtype /Type1"
-            "  /Name /F1"
-            "  /BaseFont /Helvetica"
-            "  /Encoding /WinAnsiEncoding"
-            ">>"));
+        "<<"
+        "  /Type /Font"
+        "  /Subtype /Type1"
+        "  /Name /F1"
+        "  /BaseFont /Helvetica"
+        "  /Encoding /WinAnsiEncoding"
+        ">>"_qpdf);
  
     // Create a resources dictionary with fonts. This uses the new
     // parse introduced in qpdf 10.2 that takes a QPDF* and allows
@@ -93,7 +93,7 @@ static void process(char const* infilename, char const* password,
     apdict.replaceKey("/Resources", QPDFObjectHandle::newDictionary());
     apdict.replaceKey("/Type", QPDFObjectHandle::newName("/XObject"));
     apdict.replaceKey("/Subtype", QPDFObjectHandle::newName("/Form"));
-    apdict.replaceKey("/BBox", QPDFObjectHandle::parse("[ 0 0 20 20 ]"));
+    apdict.replaceKey("/BBox", "[ 0 0 20 20 ]"_qpdf);
     auto annot = q.makeIndirectObject(
         QPDFObjectHandle::parse(
             &q,
@@ -182,12 +182,11 @@ void add_page(QPDFPageDocumentHelper&amp; dh, QPDFObjectHandle font,
     size_t width = p->getWidth();
     size_t height = p->getHeight();
     QPDFObjectHandle image = QPDFObjectHandle::newStream(&pdf);
-    image.replaceDict(QPDFObjectHandle::parse(
-                          "<<"
-                          " /Type /XObject"
-                          " /Subtype /Image"
-                          " /BitsPerComponent 8"
-                          ">>"));
+    image.replaceDict("<<"
+                      " /Type /XObject"
+                      " /Subtype /Image"
+                      " /BitsPerComponent 8"
+                      ">>"_qpdf);
     QPDFObjectHandle image_dict = image.getDict();
     image_dict.replaceKey("/ColorSpace", newName(color_space));
     image_dict.replaceKey("/Width", newInteger(width));
@@ -199,8 +198,7 @@ void add_page(QPDFPageDocumentHelper&amp; dh, QPDFObjectHandle font,
                             QPDFObjectHandle::newNull());
  
     // Create direct objects as needed by the page dictionary.
-    QPDFObjectHandle procset = QPDFObjectHandle::parse(
-        "[/PDF /Text /ImageC]");
+    QPDFObjectHandle procset = "[/PDF /Text /ImageC]"_qpdf;
  
     QPDFObjectHandle rfont = QPDFObjectHandle::newDictionary();
     rfont.replaceKey("/F1", font);
@@ -384,14 +382,13 @@ static void create_pdf(char const* filename)
     // Add an indirect object to contain a font descriptor for the
     // built-in Helvetica font.
     QPDFObjectHandle font = pdf.makeIndirectObject(
-        QPDFObjectHandle::parse(
-            "<<"
-            " /Type /Font"
-            " /Subtype /Type1"
-            " /Name /F1"
-            " /BaseFont /Helvetica"
-            " /Encoding /WinAnsiEncoding"
-            ">>"));
+        "<<"
+        " /Type /Font"
+        " /Subtype /Type1"
+        " /Name /F1"
+        " /BaseFont /Helvetica"
+        " /Encoding /WinAnsiEncoding"
+        ">>"_qpdf);
  
     std::vector<std::string> color_spaces;
     color_spaces.push_back("/DeviceCMYK");
@@ -65,8 +65,7 @@ static void stamp_page(char const* infile,
             // Append the content to the page's content. Surround the
             // original content with q...Q to the new content from the
             // page's original content.
-            resources.mergeResources(
-                QPDFObjectHandle::parse("<< /XObject << >> >>"));
+            resources.mergeResources("<< /XObject << >> >>"_qpdf);
             resources.getKey("/XObject").replaceKey(name, stamp_fo);
             ph.addPageContents(
                 QPDFObjectHandle::newStream(&inpdf, "q\n"), true);
@@ -395,7 +395,7 @@ class QPDFObjectHandle
     // object syntax (obj gen R) will cause a logic_error exception to
     // be thrown.  If object_description is provided, it will appear
     // in the message of any QPDFExc exception thrown for invalid
-    // syntax.
+    // syntax. See also the global `operator ""_qpdf` defined below.
     QPDF_DLL
     static QPDFObjectHandle parse(std::string const& object_str,
                                   std::string const& object_description = "");
@@ -1450,6 +1450,17 @@ class QPDFObjectHandle
     bool reserved;
 };
  
+#ifndef QPDF_NO_QPDF_STRING
+// This is short for QPDFObjectHandle::parse, so you can do
+
+// auto oh = "<< /Key (value) >>"_qpdf;
+
+// If this is causing problems in your code, define
+// QPDF_NO_QPDF_STRING to prevent the declaration from being here.
+QPDF_DLL
+QPDFObjectHandle operator ""_qpdf(char const* v, size_t len);
+#endif // QPDF_NO_QPDF_STRING
+
 class QPDFObjectHandle::QPDFDictItems
 {
     // This class allows C++-style iteration, including range-for
@@ -981,8 +981,7 @@ QPDFFormFieldObjectHelper::generateTextAppearance(
                 AS.getDict().replaceKey("/Resources", resources);
             }
             // Use mergeResources to force /Font to be local
-            resources.mergeResources(
-                QPDFObjectHandle::parse("<< /Font << >> >>"));
+            resources.mergeResources("<< /Font << >> >>"_qpdf);
             resources.getKey("/Font").replaceKey(font_name, font);
         }
  
@@ -2281,8 +2281,7 @@ QPDFJob::doUnderOverlayForPage(
             from_page, cm, dest_afdh, make_afdh(from_page));
         if (! new_content.empty())
         {
-            resources.mergeResources(
-                QPDFObjectHandle::parse("<< /XObject << >> >>"));
+            resources.mergeResources("<< /XObject << >> >>"_qpdf);
             auto xobject = resources.getKey("/XObject");
             if (xobject.isDictionary())
             {
@@ -61,8 +61,7 @@ QPDFNameTreeObjectHelper
 QPDFNameTreeObjectHelper::newEmpty(QPDF& qpdf, bool auto_repair)
 {
     return QPDFNameTreeObjectHelper(
-        qpdf.makeIndirectObject(
-            QPDFObjectHandle::parse("<< /Names [] >>")), qpdf, auto_repair);
+        qpdf.makeIndirectObject("<< /Names [] >>"_qpdf), qpdf, auto_repair);
 }
  
 QPDFNameTreeObjectHelper::iterator::iterator(
@@ -58,8 +58,7 @@ QPDFNumberTreeObjectHelper
 QPDFNumberTreeObjectHelper::newEmpty(QPDF& qpdf, bool auto_repair)
 {
     return QPDFNumberTreeObjectHelper(
-        qpdf.makeIndirectObject(
-            QPDFObjectHandle::parse("<< /Nums [] >>")), qpdf, auto_repair);
+        qpdf.makeIndirectObject("<< /Nums [] >>"_qpdf), qpdf, auto_repair);
 }
  
 QPDFNumberTreeObjectHelper::iterator::iterator(
@@ -3666,3 +3666,10 @@ QPDFObjectHandle::QPDFArrayItems::end()
 {
     return iterator(oh, false);
 }
+
+QPDFObjectHandle
+operator ""_qpdf(char const* v, size_t len)
+{
+    return QPDFObjectHandle::parse(
+        std::string(v, len), "QPDFObjectHandle literal");
+}
@@ -161,8 +161,7 @@ QPDFPageDocumentHelper::flattenAnnotationsForPage(
                 name, rotate, required_flags, forbidden_flags);
             if (! content.empty())
             {
-                resources.mergeResources(
-                    QPDFObjectHandle::parse("<< /XObject << >> >>"));
+                resources.mergeResources("<< /XObject << >> >>"_qpdf);
                 resources.getKey("/XObject").replaceKey(name, as);
                 ++next_fx;
             }
@@ -500,8 +500,7 @@ QPDFPageObjectHelper::externalizeInlineImages(size_t min_size, bool shallow)
         QPDFObjectHandle resources = getAttribute("/Resources", true);
         // Calling mergeResources also ensures that /XObject becomes
         // direct and is not shared with other pages.
-        resources.mergeResources(
-            QPDFObjectHandle::parse("<< /XObject << >> >>"));
+        resources.mergeResources("<< /XObject << >> >>"_qpdf);
         InlineImageTracker iit(this->oh.getOwningQPDF(), min_size, resources);
         Pl_Buffer b("new page content");
         bool filtered = false;
@@ -1255,10 +1255,8 @@ static void test_31(QPDF&amp; pdf, char const* arg2)
 {
     // Test object parsing from a string.  The input file is not used.
  
-    QPDFObjectHandle o1 =
-        QPDFObjectHandle::parse(
-            "[/name 16059 3.14159 false\n"
-            " << /key true /other [ (string1) (string2) ] >> null]");
+    auto o1 = "[/name 16059 3.14159 false\n"
+        " << /key true /other [ (string1) (string2) ] >> null]"_qpdf;
     std::cout << o1.unparse() << std::endl;
     QPDFObjectHandle o2 = QPDFObjectHandle::parse("   12345 \f  ");
     assert(o2.isInteger() && (o2.getIntValue() == 12345));