From f411e9b86ebc9c8a5fbae7fc2b51c1f017005f74 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 9 Dec 2016 17:58:26 +0000
Subject: Macro helper for easily adding new formatters

---
 libadhocutil/compileTimeFormatter.h                | 25 ++++++++++++-----
 .../unittests/testCompileTimeFormatter.cpp         | 31 +++++++++++++++-------
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/libadhocutil/compileTimeFormatter.h b/libadhocutil/compileTimeFormatter.h
index e17270a..501e0a7 100644
--- a/libadhocutil/compileTimeFormatter.h
+++ b/libadhocutil/compileTimeFormatter.h
@@ -1,6 +1,7 @@
 #include <iostream>
 #include <string.h>
 #include <boost/static_assert.hpp>
+#include <boost/preprocessor/variadic/size.hpp>
 
 namespace AdHoc {
 	constexpr int WRAP_AT = 120;
@@ -69,25 +70,37 @@ namespace AdHoc {
 		static void write(stream &, const Pn & ...) { }
 	};
 
+	template<const char * const & S, int start, int len, typename stream, char ... sn>
+	struct StreamWriterBase {
+		template<typename ... Pn>
+		static void next(stream & s, const Pn & ... pn)
+		{
+			StreamWriter<S, start + len, stream, sn...>::write(s, pn...);
+		}
+	};
+
+#define StreamWriterT(C...) \
+	template<const char * const & S, int start, typename stream, char ... sn> \
+	struct StreamWriter<S, start, stream, '%', C, sn...> : \
+		public StreamWriterBase<S, start, BOOST_PP_VARIADIC_SIZE(C) + 1, stream, sn...>
+
 	// Default stream writer formatter
-	template<const char * const & S, int start, typename stream, char ... sn>
-	struct StreamWriter<S, start, stream, '%', '?', sn...> {
+	StreamWriterT('?') {
 		template<typename P, typename ... Pn>
 		static void write(stream & s, const P & p, const Pn & ... pn)
 		{
 			s << p;
-			StreamWriter<S, start + 2, stream, sn...>::write(s, pn...);
+			StreamWriter::next(s, pn...);
 		}
 	};
 
 	// Escaped % stream writer formatter
-	template<const char * const & S, int start, typename stream, char ... sn>
-	struct StreamWriter<S, start, stream, '%', '%', sn...> {
+	StreamWriterT('%') {
 		template<typename ... Pn>
 		static void write(stream & s, const Pn & ... pn)
 		{
 			s << '%';
-			StreamWriter<S, start + 2, stream, sn...>::write(s, pn...);
+			StreamWriter::next(s, pn...);
 		}
 	};
 
diff --git a/libadhocutil/unittests/testCompileTimeFormatter.cpp b/libadhocutil/unittests/testCompileTimeFormatter.cpp
index 2c5bedf..7ecd50e 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 * formatStringCustom = "custom %()";
+extern constexpr const char * formatStringCustomLong = "custom %(longname)";
+extern constexpr const char * formatStringLong = "                                                                                                                                                                                                                                                      ";
+extern constexpr const char * formatStringMultiArg = "value%ra";
 extern constexpr const char * formatStringEscape1 = "literal %% percentage.";
 extern constexpr const char * formatStringEscape2 = "literal %%? percentage.";
 extern constexpr const char * formatStringEscape3 = "literal %%%? percentage.";
@@ -23,19 +27,25 @@ extern constexpr const char * formatStringEscape4 = "literal %%%?%% percentage."
 
 namespace AdHoc {
 	// Custom stream writer formatter, formats as (bracketed expression)
-	template<const char * const & S, int start, typename stream, char ... sn>
-	struct StreamWriter<S, start, stream, '%', '(', ')', sn...> {
+	StreamWriterT('(', ')') {
 		template<typename P, typename ... Pn>
 		static void write(stream & s, const P & p, const Pn & ... pn)
 		{
 			s << "-( " << p << " )-";
-			StreamWriter<S, start + 3, stream, sn...>::write(s, pn...);
+			StreamWriter::next(s, pn...);
+		}
+	};
+	StreamWriterT('(', 'l', 'o', 'n', 'g', 'n', 'a', 'm', 'e', ')') {
+		template<typename P, typename ... Pn>
+		static void write(stream & s, const P & p, const Pn & ... pn)
+		{
+			s << "---( " << p << " )---";
+			StreamWriter::next(s, pn...);
 		}
 	};
 	// Custom stream writer formatter, formats
 	//            right-aligned by given width
-	template<const char * const & S, int start, typename stream, char ... sn>
-	struct StreamWriter<S, start, stream, '%', 'r', 'a', sn...> {
+	StreamWriterT('r', 'a') {
 		template<typename P, typename ... Pn>
 		static void write(stream & s, int width, const P & p, const Pn & ... pn)
 		{
@@ -43,7 +53,7 @@ namespace AdHoc {
 			buf << p;
 			std::string spaces(width - buf.str().length(), ' ');
 			s << spaces << buf.str();
-			StreamWriter<S, start + 3, stream, sn...>::write(s, pn...);
+			StreamWriter::next(s, pn...);
 		}
 	};
 }
@@ -135,13 +145,18 @@ BOOST_AUTO_TEST_CASE ( escape4 )
 	BOOST_REQUIRE_EQUAL(this->str(), "literal %3% percentage.");
 }
 
-extern constexpr const char * formatStringCustom = "custom %()";
 BOOST_AUTO_TEST_CASE ( customBracketted )
 {
 	Formatter<formatStringCustom>::write(*this, "expr");
 	BOOST_REQUIRE_EQUAL(this->str(), "custom -( expr )-");
 }
 
+BOOST_AUTO_TEST_CASE ( customLongName )
+{
+	Formatter<formatStringCustomLong>::write(*this, "some text here");
+	BOOST_REQUIRE_EQUAL(this->str(), "custom ---( some text here )---");
+}
+
 typedef Formatter<formatStringCustom> TestFormat;
 BOOST_AUTO_TEST_CASE ( typedefFormat )
 {
@@ -149,7 +164,6 @@ BOOST_AUTO_TEST_CASE ( typedefFormat )
 	BOOST_REQUIRE_EQUAL(this->str(), "custom -( expr )-");
 }
 
-extern constexpr const char * formatStringLong = "                                                                                                                                                                                                                                                      ";
 BOOST_AUTO_TEST_CASE ( longFormatString )
 {
 	Formatter<formatStringLong>::write(*this);
@@ -158,7 +172,6 @@ BOOST_AUTO_TEST_CASE ( longFormatString )
 
 BOOST_AUTO_TEST_SUITE_END();
 
-extern constexpr const char * formatStringMultiArg = "value%ra";
 BOOST_AUTO_TEST_CASE ( customMultiArgRightAlign )
 {
 	std::stringstream buf1, buf2, buf3;
-- 
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