Rename string gen to IOStreams::String.

IOStreams/String.h

@@ -0,0 +1,61 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+#include <sstream>
+
+#include <Alepha/Concepts.h>
+
+namespace Alepha::Hydrogen::IOStreams  ::detail::  string
+{
+	inline namespace exports
+	{
+		class String;
+
+		enum { FinishString };
+
+		std::string stringify( const Alepha::OStreamable auto &item, Alepha::OStreamable auto && ... params );
+	}
+
+	class exports::String
+	{
+		private:
+			// TODO: We need the exception throwing capabilities of the
+			// `boost::lexical_cast` operation.  But this stream technique
+			// lets us build strings using stream modifiers and manipulators,
+			// which `boost::lexical_cast` doesn't support.
+			std::ostringstream oss;
+
+		public:
+			String &&
+			operator << ( const Alepha::OStreamable auto &t ) &&
+			{
+				oss << t;
+				return std::move( *this );
+			}
+
+			std::string
+			operator << ( decltype( FinishString ) ) &&
+			{
+				return std::move( oss ).str();
+			}
+
+			operator std::string () &&
+			{
+				return std::move( *this ) << FinishString;
+			}
+	};
+
+	inline std::string
+	exports::stringify( const Alepha::OStreamable auto &item, Alepha::OStreamable auto && ... params )
+	{
+		return ( String{} << ... << params ) << item << FinishString;
+	}
+}
+
+namespace Alepha::Hydrogen::IOStreams::inline exports::inline string
+{
+	using namespace detail::string::exports;
+}