From bacaa9fcee300f388054bbb0360e5d98acf41acb Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@recursive.engineer>
Date: Wed, 25 Oct 2023 03:55:42 -0400
Subject: [PATCH] Make stream state have a default-construction option.

Start integrating it for the field delimiters.
---
 IOStreams/OStreamable.test/0.cc | 36 ++++++++++++++++++++++++++++++++-
 IOStreams/StreamState.h         |  6 +++---
 IOStreams/delimiters.h          | 13 ++++++++++--
 3 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/IOStreams/OStreamable.test/0.cc b/IOStreams/OStreamable.test/0.cc
index 75280cd..21486b0 100644
--- a/IOStreams/OStreamable.test/0.cc
+++ b/IOStreams/OStreamable.test/0.cc
@@ -30,10 +30,28 @@ namespace
 	stringify( const Agg &agg, const std::string delim )
 	{
 		std::ostringstream oss;
+		Alepha::IOStreams::setGlobalFieldDelimiter( "YOU SHOULD NOT SEE THIS" );
 		oss << Alepha::IOStreams::setFieldDelimiter( delim );
 		oss << agg;
 		return std::move( oss ).str();
 	}
+
+	auto
+	stringify_global( const Agg &agg, const std::string delim )
+	{
+		std::ostringstream oss;
+		Alepha::IOStreams::setGlobalFieldDelimiter( delim );
+		oss << agg;
+		return std::move( oss ).str();
+	}
+
+	auto
+	stringify_default( const Agg &agg )
+	{
+		std::ostringstream oss;
+		oss << agg;
+		return std::move( oss ).str();
+	}
 }
 
 static auto init= Alepha::Utility::enroll <=[]
@@ -41,7 +59,13 @@ static auto init= Alepha::Utility::enroll <=[]
 	using namespace Alepha::Testing::exports;
 	using namespace Alepha::Testing::literals::test_literals;
 
-	"Simple OStream"_test <=TableTest< stringify >
+	"Simple OStream (default delimiter)"_test <=TableTest< stringify_default >
+	::Cases
+	{
+		{ "smoke test", { { 1, 2, 3 } }, { "1\t2\t3" } },
+	};
+
+	"Simple OStream (specific delimiter)"_test <=TableTest< stringify >
 	::Cases
 	{
 		{ "smoke test", { { 1, 2, 3 }, "\t" }, { "1\t2\t3" } },
@@ -49,4 +73,14 @@ static auto init= Alepha::Utility::enroll <=[]
 		{ "smoke test", { { 1, 2, 3 }, ";;" }, { "1;;2;;3" } },
 		{ "smoke test", { { 1, 2, 3 }, ", " }, { "1, 2, 3" } },
 	};
+
+	"Simple OStream (global delimiter)"_test <=TableTest< stringify_global >
+	::Cases
+	{
+		{ "smoke test", { { 1, 2, 3 }, "\t" }, { "1\t2\t3" } },
+		{ "smoke test", { { 1, 2, 3 }, "," }, { "1,2,3" } },
+		{ "smoke test", { { 1, 2, 3 }, ";;" }, { "1;;2;;3" } },
+		{ "smoke test", { { 1, 2, 3 }, ", " }, { "1, 2, 3" } },
+	};
+
 };
diff --git a/IOStreams/StreamState.h b/IOStreams/StreamState.h
index 0f32f40..dc23936 100644
--- a/IOStreams/StreamState.h
+++ b/IOStreams/StreamState.h
@@ -11,11 +11,11 @@ namespace Alepha::Hydrogen::IOStreams  ::detail::  stream_state
 {
 	inline namespace exports
 	{
-		template< typename Tag, typename Type >
+		template< typename Tag, typename Type, auto Default= [] { return Type{}; } >
 		class StreamState;
 	}
 
-	template< typename Tag, typename Type >
+	template< typename Tag, typename Type, auto Default >
 	class exports::StreamState
 	{
 		private:
@@ -70,7 +70,7 @@ namespace Alepha::Hydrogen::IOStreams  ::detail::  stream_state
 					ios.register_callback( callback, index() );
 				}
 				auto *&ptr= get_ptr( ios );
-				if( not ptr ) ptr= new Type{};
+				if( not ptr ) ptr= new Type{ Default() };
 			}
 
 		public:
diff --git a/IOStreams/delimiters.h b/IOStreams/delimiters.h
index 097f4cd..6f543e3 100644
--- a/IOStreams/delimiters.h
+++ b/IOStreams/delimiters.h
@@ -20,8 +20,6 @@ namespace Alepha::Hydrogen::IOStreams  ::detail::  delimiters
 		enum { RecordDelimiter };
 	}
 
-	using FieldDelimiterState= StreamState< decltype( FieldDelimiter ), std::string >;
-
 	namespace C
 	{
 		const std::string defaultFieldDelimiter= "\t";
@@ -41,6 +39,15 @@ namespace Alepha::Hydrogen::IOStreams  ::detail::  delimiters
 		return storage::globalFieldDelimiter().value();
 	}
 
+	namespace exports
+	{
+		inline void
+		setGlobalFieldDelimiter( const std::string delim )
+		{
+			storage::globalFieldDelimiter()= delim;
+		}
+	}
+
 	inline char
 	globalRecordDelimiter()
 	{
@@ -48,6 +55,8 @@ namespace Alepha::Hydrogen::IOStreams  ::detail::  delimiters
 		return storage::globalRecordDelimiter().value();
 	}
 
+	using FieldDelimiterState= StreamState< decltype( FieldDelimiter ), std::string, globalFieldDelimiter >;
+
 	inline std::ostream &
 	operator << ( std::ostream &os, decltype( FieldDelimiter ) )
 	{