From 2b6dfe07cd1692ebe9fe7fe3ae924567ff5b417f Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 17 Jun 2018 18:11:09 +0100
Subject: Any stream type with CTF

Minor alteration to allow for custom helpers. Then a unit test to
demonstrate that with suitable helpers, a CTF can operate on any stream
type, such as a stdio FILE.
---
 libadhocutil/compileTimeFormatter.h                |  8 ++++++-
 .../unittests/testCompileTimeFormatter.cpp         | 28 ++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/libadhocutil/compileTimeFormatter.h b/libadhocutil/compileTimeFormatter.h
index f409b1c..fecbd91 100644
--- a/libadhocutil/compileTimeFormatter.h
+++ b/libadhocutil/compileTimeFormatter.h
@@ -89,6 +89,12 @@ namespace AdHoc {
 		}
 	};
 
+	template<typename stream, typename char_type>
+	static inline void appendStream(stream & s, const char_type * p, size_t n)
+	{
+		s.write(p, n);
+	}
+
 	/**
 	 * Compile time string formatter.
 	 * @param S the format string.
@@ -133,7 +139,7 @@ namespace AdHoc {
 					if (pos != L) {
 						constexpr auto ph = strchrnul<S, '%', pos, L>();
 						if constexpr (ph != pos) {
-							s.write((S + pos), ph - pos);
+							appendStream(s, (S + pos), ph - pos);
 						}
 						if constexpr (ph != L) {
 							packAndWrite<ph>(s, pn...);
diff --git a/libadhocutil/unittests/testCompileTimeFormatter.cpp b/libadhocutil/unittests/testCompileTimeFormatter.cpp
index 9d01a80..a04b92e 100644
--- a/libadhocutil/unittests/testCompileTimeFormatter.cpp
+++ b/libadhocutil/unittests/testCompileTimeFormatter.cpp
@@ -280,3 +280,31 @@ BOOST_AUTO_TEST_CASE( lorem_ipsum )
 	BOOST_CHECK_EQUAL_COLLECTIONS(s.begin(), s.end(), sv.begin(), sv.end());
 }
 
+namespace AdHoc {
+	template<>
+	inline void appendStream(FILE & strm, const char * const p, size_t n)
+	{
+		BOOST_VERIFY(fwrite(p, n, 1, &strm) == 1);
+	}
+}
+
+FILE &
+operator<<(FILE & strm, const char * const p)
+{
+	BOOST_VERIFY(fputs(p, &strm) != EOF);
+	return strm;
+}
+
+BOOST_AUTO_TEST_CASE( filestar )
+{
+	char * buf = NULL;
+	size_t len = 0;
+	FILE * strm = open_memstream(&buf, &len);
+	BOOST_REQUIRE(strm);
+	Formatter<formatStringMulti>::write(*strm, "file", "star");
+	fclose(strm);
+	BOOST_CHECK_EQUAL(len, 22);
+	BOOST_CHECK_EQUAL(buf, "First file, then star.");
+	free(buf);
+}
+
-- 
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