clean up Value of XMLDocument

tinyxml2.cpp

@@ -645,6 +645,9 @@ XMLNode::~XMLNode()
 
 const char* XMLNode::Value() const 
 {
+    // Catch an edge case: XMLDocuments don't have a a Value. Carefully return nullptr.
+    if ( this->ToDocument() )
+        return 0;
     return _value.GetStr();
 }
 

tinyxml2.h

@@ -708,7 +708,7 @@ public:
 
     /** The meaning of 'value' changes for the specific type.
     	@verbatim
-    	Document:	empty
+    	Document:	empty (NULL is returned, not an empty string)
     	Element:	name of the element
     	Comment:	the comment text
     	Unknown:	the tag contents

xmltest.cpp

@@ -30,7 +30,13 @@ int gFail = 0;
 
 bool XMLTest (const char* testString, const char* expected, const char* found, bool echo=true, bool extraNL=false )
 {
-	bool pass = !strcmp( expected, found );
+	bool pass;
+	if ( !expected && !found )
+		pass = true;
+	else if ( !expected || !found )
+		pass = false;
+	else 
+		pass = !strcmp( expected, found );
 	if ( pass )
 		printf ("[pass]");
 	else
@@ -1479,6 +1485,19 @@ int main( int argc, const char ** argv )
 	    XMLTest("Test that declaration after a child throws an error", doc.ErrorID(), XML_ERROR_PARSING_DECLARATION);
 	}
 
+    {
+	    // No matter - before or after successfully parsing a text -
+	    // calling XMLDocument::Value() causes an assert in debug.
+	    const char* validXml = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>"
+	                           "<first />"
+	                           "<second />";
+	    XMLDocument* doc = new XMLDocument();
+	    XMLTest( "XMLDocument::Value() returns null?", NULL, doc->Value() );
+	    doc->Parse( validXml );
+	    XMLTest( "XMLDocument::Value() returns null?", NULL, doc->Value() );
+	    delete doc;
+    }
+
     // ----------- Performance tracking --------------
 	{
 #if defined( _MSC_VER )