From 08971abb0631b62b0fee6aabc4d2eb90a37fd1e5 Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@recursive.engineer>
Date: Sun, 22 Oct 2023 04:43:25 -0400
Subject: [PATCH] Add IStreamable helper.

---
 CMakeLists.txt                            |  1 +
 IOStreams/CMakeLists.txt                  |  1 +
 IOStreams/IStreamable.h                   | 60 +++++++++++++++++++++++
 IOStreams/IStreamable.test/0.cc           | 52 ++++++++++++++++++++
 IOStreams/IStreamable.test/CMakeLists.txt |  2 +
 5 files changed, 116 insertions(+)
 create mode 100644 IOStreams/CMakeLists.txt
 create mode 100644 IOStreams/IStreamable.h
 create mode 100644 IOStreams/IStreamable.test/0.cc
 create mode 100644 IOStreams/IStreamable.test/CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8ce0158..2ce4949 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,6 +19,7 @@ link_libraries( alepha )
 # The subdirs to build
 add_subdirectory( Meta )
 add_subdirectory( Proof )
+add_subdirectory( IOStreams )
 add_subdirectory( Reflection )
 add_subdirectory( Testing )
 add_subdirectory( Utility )
diff --git a/IOStreams/CMakeLists.txt b/IOStreams/CMakeLists.txt
new file mode 100644
index 0000000..f44cb48
--- /dev/null
+++ b/IOStreams/CMakeLists.txt
@@ -0,0 +1 @@
+add_subdirectory( IStreamable.test )
diff --git a/IOStreams/IStreamable.h b/IOStreams/IStreamable.h
new file mode 100644
index 0000000..54010f7
--- /dev/null
+++ b/IOStreams/IStreamable.h
@@ -0,0 +1,60 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+#include <istream>
+
+#include <Alepha/Capabilities.h>
+#include <Alepha/template_for_each.h>
+#include <Alepha/string_algorithms.h>
+#include <Alepha/Concepts.h>
+
+#include <Alepha/Reflection/tuplizeAggregate.h>
+
+namespace Alepha::Hydrogen::IOStreams  ::detail::  istreamable_module
+{
+	inline namespace exports
+	{
+		struct IStreamable {};
+	}
+
+	template< typename T >
+	concept IStreamableAggregate= Aggregate< T > and Capability< T, IStreamable >;
+
+
+	std::istream &
+	operator >> ( std::istream &is, IStreamableAggregate auto &istreamable )
+	{
+		std::string line;
+		std::getline( is, line );
+		const auto commentChar= line.find( "#" );
+		if( commentChar != std::string::npos ) line= line.substr( line.find( "#" ) );
+
+		const auto tokens= split( line, '\t' );
+
+		auto decomposed= Alepha::Reflection::tuplizeAggregate( istreamable );
+
+		if( tokens.size() != std::tuple_size_v< std::decay_t< decltype( decomposed ) > > )
+		{
+			throw 0;
+		}
+
+		int index= 0;
+		// TODO: Consider the lens system here... but the basic use case seems to be for
+		// aggregates, so we'll go with this simple case for now...
+		tuple_for_each( decomposed ) <=[&]( auto &element )
+		{
+			std::istringstream iss{ tokens.at( index++ ) };
+			iss >> element;
+		};
+
+		return is;
+	}
+}
+
+namespace Alepha::Hydrogen::IOStreams::inline exports::inline istreamable_module
+{
+	using namespace detail::istreamable_module::exports;
+}
diff --git a/IOStreams/IStreamable.test/0.cc b/IOStreams/IStreamable.test/0.cc
new file mode 100644
index 0000000..8b4537a
--- /dev/null
+++ b/IOStreams/IStreamable.test/0.cc
@@ -0,0 +1,52 @@
+static_assert( __cplusplus > 2020'00 );
+
+#include "../IStreamable.h"
+
+#include <Alepha/Testing/TableTest.h>
+#include <Alepha/Testing/test.h>
+
+#include <sstream>
+
+namespace
+{
+	template< typename= Alepha::Capabilities< Alepha::IOStreams::IStreamable > >
+	struct Agg_core
+	{
+		int x;
+		int y;
+		int z;
+
+		friend bool operator == ( const Agg_core &lhs, const Agg_core &rhs )= default;
+		friend std::ostream &
+		operator << ( std::ostream &os, const Agg_core &agg )
+		{
+			return os << "{ " << agg.x << ", " << agg.y << ", " << agg.z << " }";
+		}
+	};
+
+	using Agg= Agg_core<>;
+	static_assert( Alepha::Aggregate< Agg > );
+	static_assert( Alepha::Capability< Agg, Alepha::IOStreams::IStreamable > );
+}
+
+
+auto
+buildFromString( const std::string text )
+{
+	Agg rv;
+	std::istringstream iss{ text };
+	iss >> rv;
+	return rv;
+}
+
+static auto init= Alepha::Utility::enroll <=[]
+{
+	using namespace Alepha::Testing::exports;
+	using namespace Alepha::Testing::literals::test_literals;
+
+	"Simple IStream"_test <=TableTest< buildFromString >
+	::Cases
+	{
+		{ "smoke test", { "1\t2\t3" }, { 1, 2, 3 } },
+	};
+};
diff --git a/IOStreams/IStreamable.test/CMakeLists.txt b/IOStreams/IStreamable.test/CMakeLists.txt
new file mode 100644
index 0000000..d31c4a6
--- /dev/null
+++ b/IOStreams/IStreamable.test/CMakeLists.txt
@@ -0,0 +1,2 @@
+link_libraries( unit-test )
+unit_test( 0 )