From f6ff54c492df81018cf48da039ee681508f88e46 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sat, 16 Aug 2014 23:30:36 +0200
Subject: Implemented primitive optional parameter support for external
 functions * renamed FunctionExternalTextFormatter into
 FunctionExternalCommand ** the goal is to provide a general interface to a
 variety of external commands *** e.g. not just text formatters but system
 utilities for file management and so on ** this requires the stdin parameter
 to be optional as not all external commands require stdin input * implemented
 "filter_derived" helper template to determine amount of optional parameters
 ** optional parameters are defined as "boost::optional" specializations ***
 they in turn can be detected by checking if
 "boost::optional_detail::optional_tag" is a base class *
 "callConstructDocument" member method of "FunctionBase" performs additional
 bounds checking of parameter vector * "boost::optional<std::string>" specific
 member overload was added to "XObjectValue" helper class ** we will have to
 provide full specializations for all optional types as C++ prohibits partial
 member function template specialization * renamed the external function in
 "PlattformGuard" * changed README.md and test cases accordingly

---
 src/support/type/filter.h         | 24 ++++++++++++++++++++++++
 src/support/type/xobject_value.cc | 13 ++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 src/support/type/filter.h

(limited to 'src/support/type')

diff --git a/src/support/type/filter.h b/src/support/type/filter.h
new file mode 100644
index 0000000..4a0e19f
--- /dev/null
+++ b/src/support/type/filter.h
@@ -0,0 +1,24 @@
+#ifndef INPUTXSLT_SRC_SUPPORT_TYPE_FILTER_H_
+#define INPUTXSLT_SRC_SUPPORT_TYPE_FILTER_H_
+
+#include <tuple>
+#include <type_traits>
+
+namespace InputXSLT {
+
+template <
+	typename BaseReference,
+	typename Head,
+	typename... Tail
+>
+struct filter_derived {
+	typedef typename std::conditional<
+		std::is_base_of<BaseReference, Head>::value,
+		std::tuple<Head, Tail...>,
+		std::tuple<Tail...>
+	>::type type;
+};
+
+}
+
+#endif  // INPUTXSLT_SRC_SUPPORT_TYPE_FILTER_H_
diff --git a/src/support/type/xobject_value.cc b/src/support/type/xobject_value.cc
index 9bb6648..e457a69 100644
--- a/src/support/type/xobject_value.cc
+++ b/src/support/type/xobject_value.cc
@@ -4,7 +4,8 @@
 #include <xalanc/XalanDOM/XalanDocumentFragment.hpp>
 
 #include <boost/algorithm/string.hpp>
-#include "boost/filesystem.hpp"
+#include <boost/filesystem.hpp>
+#include <boost/optional.hpp>
 
 #include <string>
 
@@ -26,6 +27,16 @@ std::string XObjectValue::get<std::string>(
 	return boost::trim_copy(toString(ptr->str()));
 }
 
+template <>
+boost::optional<std::string> XObjectValue::get<boost::optional<std::string>>(
+	const xalan::XObjectPtr& ptr) const {
+	if ( ptr.null() ) {
+		return boost::optional<std::string>();
+	} else {
+		return this->get<std::string>(ptr);
+	}
+}
+
 template <>
 boost::filesystem::path XObjectValue::get<boost::filesystem::path>(
 	const xalan::XObjectPtr& ptr) const {
-- 
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