Add QPDFObjectHandle::wrapInArray()

Wrap an object in an array if it is not already an array.

ChangeLog

@@ -1,3 +1,11 @@
+2018-12-18  Jay Berkenbilt  <ejb@ql.org>
+
+	* New method QPDFObjectHandle::wrapInArray returns the object
+	itself if it is an array. Otherwise, it returns an array
+	containing the object. This is useful for dealing with PDF data
+	that is sometimes expressed as a single element and sometimes
+	expressed as an array, which is a somewhat common PDF idiom.
+
 2018-10-11  Jay Berkenbilt  <ejb@ql.org>
 
 	* Files generated by autogen.sh are now committed so that it is

include/qpdf/QPDFObjectHandle.hh

@@ -255,6 +255,12 @@ class QPDFObjectHandle
 
     // Public factory methods
 
+    // Wrap an object in an array if it is not already an array. This
+    // is a helper for cases in which something in a PDF may either be
+    // a single item or an array of items, which is a common idiom.
+    QPDF_DLL
+    QPDFObjectHandle wrapInArray();
+
     // Construct an object of any type from a string representation of
     // the object.  Throws QPDFExc with an empty filename and an
     // offset into the string if there is an error.  Any indirect

libqpdf/QPDFObjectHandle.cc

@@ -1235,6 +1235,18 @@ QPDFObjectHandle::unparseBinary()
     }
 }
 
+QPDFObjectHandle
+QPDFObjectHandle::wrapInArray()
+{
+    if (isArray())
+    {
+        return *this;
+    }
+    QPDFObjectHandle result = QPDFObjectHandle::newArray();
+    result.appendItem(*this);
+    return result;
+}
+
 QPDFObjectHandle
 QPDFObjectHandle::parse(std::string const& object_str,
                         std::string const& object_description)