Factor common code out of the xml_format files.

base/xml_utils.h

@@ -0,0 +1,42 @@
+#ifndef BASE_XML_UTILS_H
+#define BASE_XML_UTILS_H
+
+#include <boost/lexical_cast.hpp>
+#include <boost/optional.hpp>
+#include <map>
+
+using namespace std;
+
+//----------------------------------------------------------------
+
+namespace xml_utils {
+	typedef std::map<std::string, std::string> attributes;
+
+	void build_attributes(attributes &a, char const **attr);
+
+	template <typename T>
+	T get_attr(attributes const &attr, string const &key) {
+		attributes::const_iterator it = attr.find(key);
+		if (it == attr.end()) {
+			ostringstream out;
+			out << "could not find attribute: " << key;
+			throw runtime_error(out.str());
+		}
+
+		return boost::lexical_cast<T>(it->second);
+	}
+
+	template <typename T>
+	boost::optional<T> get_opt_attr(attributes const &attr, string const &key) {
+		typedef boost::optional<T> rtype;
+		attributes::const_iterator it = attr.find(key);
+		if (it == attr.end())
+			return rtype();
+
+		return rtype(boost::lexical_cast<T>(it->second));
+	}
+}
+
+//----------------------------------------------------------------
+
+#endif