From ec8f0c1e1c9e92fde33577b469b7b778c60b4c48 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 6 Feb 2019 16:27:48 -0800
Subject: [PATCH] ircd::m::event: Add refs interface.

---
 include/ircd/m/event.h       |  1 +
 include/ircd/m/event/event.h |  1 +
 include/ircd/m/event/refs.h  | 34 ++++++++++++++++++
 ircd/m_event.cc              | 69 ++++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+)
 create mode 100644 include/ircd/m/event/refs.h

diff --git a/include/ircd/m/event.h b/include/ircd/m/event.h
index ad9ae14b6..e68f4477e 100644
--- a/include/ircd/m/event.h
+++ b/include/ircd/m/event.h
@@ -33,6 +33,7 @@ namespace ircd::m
 
 #include "event/event.h"
 #include "event/prev.h"
+#include "event/refs.h"
 #include "event/index.h"
 #include "event/fetch.h"
 #include "event/get.h"
diff --git a/include/ircd/m/event/event.h b/include/ircd/m/event/event.h
index d235b15f2..ab7d4b94a 100644
--- a/include/ircd/m/event/event.h
+++ b/include/ircd/m/event/event.h
@@ -78,6 +78,7 @@ struct ircd::m::event
 >
 {
 	struct prev;
+	struct refs;
 	struct fetch;
 	struct conforms;
 
diff --git a/include/ircd/m/event/refs.h b/include/ircd/m/event/refs.h
new file mode 100644
index 000000000..1784185ed
--- /dev/null
+++ b/include/ircd/m/event/refs.h
@@ -0,0 +1,34 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_M_EVENT_REFS_H
+
+struct ircd::m::event::refs
+{
+	using closure_bool = event::closure_idx_bool;
+
+	event::idx idx;
+
+  public:
+	bool for_each(const closure_bool &) const;
+	bool has(const event::idx &) const noexcept;
+	size_t count() const noexcept;
+
+	refs(const event::idx &idx) noexcept;
+};
+
+inline
+ircd::m::event::refs::refs(const event::idx &idx)
+noexcept
+:idx{idx}
+{
+	assert(idx);
+}
diff --git a/ircd/m_event.cc b/ircd/m_event.cc
index cf0b70e53..d4fb24158 100644
--- a/ircd/m_event.cc
+++ b/ircd/m_event.cc
@@ -1034,6 +1034,75 @@ ircd::m::index(const event::id &event_id,
 	});
 }
 
+///////////////////////////////////////////////////////////////////////////////
+//
+// event/refs.h
+//
+
+size_t
+ircd::m::event::refs::count()
+const noexcept
+{
+	assert(idx);
+	size_t ret(0);
+	for_each([&ret](const auto &)
+	{
+		++ret;
+		return true;
+	});
+
+	return ret;
+}
+
+bool
+ircd::m::event::refs::has(const event::idx &idx)
+const noexcept
+{
+	return !for_each([&idx](const event::idx &ref)
+	{
+		return ref != idx; // true to continue, false to break
+	});
+}
+
+bool
+ircd::m::event::refs::for_each(const closure_bool &closure)
+const
+{
+	auto &column
+	{
+		dbs::event_refs
+	};
+
+	const byte_view<string_view> &key
+	{
+		idx
+	};
+
+	auto it
+	{
+		column.begin(key)
+	};
+
+	for(; it; ++it)
+	{
+		const auto parts
+		{
+			dbs::event_refs_key(it->first)
+		};
+
+		const auto &ref
+		{
+			std::get<0>(parts)
+		};
+
+		assert(idx != ref);
+		if(!closure(ref))
+			return false;
+	}
+
+	return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // event/prev.h