FeedReader plugin

- reserved service id
- reworked error codes
- added xpath manipulation and basic gui elements in preview dialog

git-svn-id: http://svn.code.sf.net/p/retroshare/code/branches/v0.5-gxs-b1@5514 b45a01b8-16f6-495d-af2f-9b41ad6348cc

plugins/FeedReader/util/XPathWrapper.cpp

@@ -0,0 +1,102 @@
+/****************************************************************
+ *  RetroShare GUI is distributed under the following license:
+ *
+ *  Copyright (C) 2012 by Thunder
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version 2
+ *  of the License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA  02110-1301, USA.
+ ****************************************************************/
+
+#include "XPathWrapper.h"
+#include "XMLWrapper.h"
+
+XPathWrapper::XPathWrapper(XMLWrapper &xmlWrapper) : mXMLWrapper(xmlWrapper)
+{
+	mContext = NULL;
+	mResult = NULL;
+}
+
+XPathWrapper::~XPathWrapper()
+{
+	cleanup();
+}
+
+void XPathWrapper::cleanup()
+{
+	if (mResult) {
+		xmlXPathFreeObject(mResult);
+		mResult = NULL;
+	}
+	if (mContext) {
+		xmlXPathFreeContext(mContext);
+		mContext = NULL;
+	}
+}
+
+bool XPathWrapper::compile(const char *expression)
+{
+	cleanup();
+
+	xmlDocPtr document = mXMLWrapper.getDocument();
+	if (!document) {
+		return false;
+	}
+
+	mContext = xmlXPathNewContext(document);
+	if (!mContext) {
+		cleanup();
+		return false;
+	}
+
+	xmlChar *xmlExpression = NULL;
+	if (!mXMLWrapper.convertFromString(expression, xmlExpression)) {
+		cleanup();
+		return false;
+	}
+	mResult = xmlXPathEvalExpression(xmlExpression, mContext);
+	xmlFree(xmlExpression);
+
+	return true;
+}
+
+unsigned int XPathWrapper::count()
+{
+	if (!mResult) {
+		return 0;
+	}
+
+	if (xmlXPathNodeSetIsEmpty(mResult->nodesetval)) {
+		return 0;
+	}
+
+	return mResult->nodesetval->nodeNr;
+}
+
+xmlNodePtr XPathWrapper::node(unsigned int index)
+{
+	if (!mResult) {
+		return NULL;
+	}
+
+	if (xmlXPathNodeSetIsEmpty(mResult->nodesetval)) {
+		return NULL;
+	}
+
+	if (index >= (unsigned int) mResult->nodesetval->nodeNr) {
+		return NULL;
+	}
+
+	return mResult->nodesetval->nodeTab[index];
+}