Implemented global DOM document cache

* the plan to return XML-nodes from each external function requires a better way to manage the lifetime of many xerces DOM document instances and their support class instances
** this is why DomDocumentCache and DomDocumentCache::item were implemented
** based on std::map so we can easily access the result of old function calls
* changed external read-directory function to return the children of the document node instead of the document node itself
** removes unnecessary cruft in function calls
** will make returning status codes alongside the function result more pleasing to the eye
* updated test transformation to reflect new features

1 files changed, 27 insertions, 0 deletions

diff --git a/src/support/dom/document_cache.h b/src/support/dom/document_cache.h
new file mode 100644
index 0000000..4447a18
--- /dev/null
+++ b/src/support/dom/document_cache.h
@@ -0,0 +1,27 @@
+#ifndef INPUTXSLT_SRC_SUPPORT_DOM_DOCUMENT_CACHE_H_
+#define INPUTXSLT_SRC_SUPPORT_DOM_DOCUMENT_CACHE_H_
+
+#include <map>
+#include <string>
+#include <memory>
+
+namespace InputXSLT {
+
+class DomDocumentCache {
+	public:
+		class item;
+
+		DomDocumentCache();
+
+		item* get(const std::string&);
+
+	private:
+		std::map<std::string, std::unique_ptr<item>> map_;
+
+};
+
+}
+
+#include "document_cache_item.h"
+
+#endif  // INPUTXSLT_SRC_SUPPORT_DOM_DOCUMENT_CACHE_H_