From 02f4420399a388f4c7cca0e9ab87ecf8e4286e08 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 9 Dec 2016 16:28:48 +0000
Subject: Provide a way of formatting a literal percent sign

---
 libadhocutil/compileTimeFormatter.h                | 11 +++++++
 .../unittests/testCompileTimeFormatter.cpp         | 34 +++++++++++++++++++++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/libadhocutil/compileTimeFormatter.h b/libadhocutil/compileTimeFormatter.h
index d9349dc..e17270a 100644
--- a/libadhocutil/compileTimeFormatter.h
+++ b/libadhocutil/compileTimeFormatter.h
@@ -80,6 +80,17 @@ namespace AdHoc {
 		}
 	};
 
+	// Escaped % stream writer formatter
+	template<const char * const & S, int start, typename stream, char ... sn>
+	struct StreamWriter<S, start, stream, '%', '%', sn...> {
+		template<typename ... Pn>
+		static void write(stream & s, const Pn & ... pn)
+		{
+			s << '%';
+			StreamWriter<S, start + 2, stream, sn...>::write(s, pn...);
+		}
+	};
+
 	// Unknown stream writer formatter
 	template<const char * const & S, int start, typename stream, char ... sn>
 	struct StreamWriter<S, start, stream, '%', sn...> {
diff --git a/libadhocutil/unittests/testCompileTimeFormatter.cpp b/libadhocutil/unittests/testCompileTimeFormatter.cpp
index ffb528b..b3e3dac 100644
--- a/libadhocutil/unittests/testCompileTimeFormatter.cpp
+++ b/libadhocutil/unittests/testCompileTimeFormatter.cpp
@@ -16,6 +16,10 @@ extern constexpr const char * formatEdgeCaseFormatLonely = "%?";
 extern constexpr const char * formatStringLiteral = "literal";
 extern constexpr const char * formatStringSingle = "single %?.";
 extern constexpr const char * formatStringMulti = "First %?, then %?.";
+extern constexpr const char * formatStringEscape1 = "literal %% percentage.";
+extern constexpr const char * formatStringEscape2 = "literal %%? percentage.";
+extern constexpr const char * formatStringEscape3 = "literal %%%? percentage.";
+extern constexpr const char * formatStringEscape4 = "literal %%%?%% percentage.";
 
 BOOST_AUTO_TEST_CASE ( empty )
 {
@@ -84,10 +88,38 @@ BOOST_AUTO_TEST_CASE ( singlePath )
 BOOST_AUTO_TEST_CASE ( multi )
 {
 	std::stringstream buf;
-  Formatter<formatStringMulti>::write(buf, "one", "two");
+	Formatter<formatStringMulti>::write(buf, "one", "two");
 	BOOST_REQUIRE_EQUAL(buf.str(), "First one, then two.");
 }
 
+BOOST_AUTO_TEST_CASE ( escape1 )
+{
+	std::stringstream buf;
+	Formatter<formatStringEscape1>::write(buf);
+	BOOST_REQUIRE_EQUAL(buf.str(), "literal % percentage.");
+}
+
+BOOST_AUTO_TEST_CASE ( escape2 )
+{
+	std::stringstream buf;
+	Formatter<formatStringEscape2>::write(buf);
+	BOOST_REQUIRE_EQUAL(buf.str(), "literal %? percentage.");
+}
+
+BOOST_AUTO_TEST_CASE ( escape3 )
+{
+	std::stringstream buf;
+	Formatter<formatStringEscape3>::write(buf, 3);
+	BOOST_REQUIRE_EQUAL(buf.str(), "literal %3 percentage.");
+}
+
+BOOST_AUTO_TEST_CASE ( escape4 )
+{
+	std::stringstream buf;
+	Formatter<formatStringEscape4>::write(buf, 3);
+	BOOST_REQUIRE_EQUAL(buf.str(), "literal %3% percentage.");
+}
+
 namespace AdHoc {
 	// Custom stream writer formatter, formats as (bracketed expression)
 	template<const char * const & S, int start, typename stream, char ... sn>
-- 
cgit v1.2.3