From 2f7fc20abf11a28011c828449142fb0df1ab858c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 18 Oct 2016 22:07:57 +0100
Subject: Add operator/ for resolving optional things to a final thing

---
 libadhocutil/optionals.h                 | 30 +++++++++++++++++++++
 libadhocutil/unittests/Jamfile.jam       |  8 ++++++
 libadhocutil/unittests/testOptionals.cpp | 46 ++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)
 create mode 100644 libadhocutil/optionals.h
 create mode 100644 libadhocutil/unittests/testOptionals.cpp

diff --git a/libadhocutil/optionals.h b/libadhocutil/optionals.h
new file mode 100644
index 0000000..f4d6b1a
--- /dev/null
+++ b/libadhocutil/optionals.h
@@ -0,0 +1,30 @@
+#ifndef ADHOCUTIL_OPTIONALS_H
+#define ADHOCUTIL_OPTIONALS_H
+
+#include <type_traits>
+
+namespace AdHoc {
+	template <typename A, typename B>
+	auto
+	operator/(const A & a, const B & b) -> typename std::enable_if<
+			std::is_constructible<bool, A>::value &&
+			!std::is_pointer<B>::value &&
+			std::is_convertible<decltype(*a), B>::value,
+		decltype(a ? *a : b)>::type
+	{
+		return (a ? *a : b);
+	}
+
+	template <typename A, typename B>
+	auto
+	operator/(const A & a, const B & b) -> typename std::enable_if<
+			std::is_constructible<bool, A>::value &&
+			std::is_pointer<B>::value,
+		decltype(a ? &*a : b)>::type
+	{
+		return (a ? &*a : b);
+	}
+}
+
+#endif
+
diff --git a/libadhocutil/unittests/Jamfile.jam b/libadhocutil/unittests/Jamfile.jam
index bf86e9c..5072f39 100644
--- a/libadhocutil/unittests/Jamfile.jam
+++ b/libadhocutil/unittests/Jamfile.jam
@@ -261,3 +261,11 @@ run
 	<library>boost_filesystem
 	;
 
+run
+	testOptionals.cpp
+	: : :
+	<define>BOOST_TEST_DYN_LINK
+	<library>..//adhocutil
+	<library>boost_utf
+	;
+
diff --git a/libadhocutil/unittests/testOptionals.cpp b/libadhocutil/unittests/testOptionals.cpp
new file mode 100644
index 0000000..7e5b4b1
--- /dev/null
+++ b/libadhocutil/unittests/testOptionals.cpp
@@ -0,0 +1,46 @@
+#define BOOST_TEST_MODULE Buffer
+#include <boost/test/unit_test.hpp>
+
+#include <optionals.h>
+#include <boost/optional.hpp>
+#include <IceUtil/Exception.h>
+#include <IceUtil/Optional.h>
+
+using namespace AdHoc;
+
+BOOST_AUTO_TEST_CASE ( general )
+{
+	boost::optional<int> x;
+	boost::optional<double> y = 2.3;
+	IceUtil::Optional<float> ix;
+	IceUtil::Optional<short> iy = 4;
+	std::string * p = nullptr;
+	std::string * q = new std::string("str");
+	boost::optional<std::string> r;
+	IceUtil::Optional<std::string> s;
+
+	bool b(p);
+	BOOST_REQUIRE_EQUAL(false, b);
+	auto a1 = x / y;
+	BOOST_REQUIRE(a1);
+	BOOST_REQUIRE_EQUAL(2.3, *a1);
+	auto a2 = x / 10;
+	BOOST_REQUIRE_EQUAL(10, a2);
+	auto a3 = ix /  11;
+	BOOST_REQUIRE_EQUAL(11, a3);
+	auto a4 = iy /  11;
+	BOOST_REQUIRE_EQUAL(4, a4);
+
+	auto s1 = p / s / r;
+	BOOST_REQUIRE(!s1);
+	auto s2 = q / s / r;
+	BOOST_REQUIRE(s2);
+	BOOST_REQUIRE_EQUAL("str", *s2);
+
+	auto p1 = r / q;
+	BOOST_REQUIRE(p1);
+	BOOST_REQUIRE_EQUAL("str", *p1);
+
+	delete q;
+}
+
-- 
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