From 159bebbd26b8a0c51311753d7171649ca685147e Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 16 Dec 2020 17:06:10 -0800
Subject: [PATCH] ircd::m::event: Add more ergonomic bulk id/idx extraction
 interface.

---
 include/ircd/m/event/auth.h  | 42 ++++++++++++++++++++++++++++++++++++
 include/ircd/m/event/event.h |  2 +-
 include/ircd/m/event/prev.h  | 42 ++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/include/ircd/m/event/auth.h b/include/ircd/m/event/auth.h
index 8f210f83f..058d149f6 100644
--- a/include/ircd/m/event/auth.h
+++ b/include/ircd/m/event/auth.h
@@ -37,6 +37,8 @@ struct ircd::m::event::auth
 		5
 	};
 
+	template<size_t N> vector_view<event::id> ids(event::id (&)[N]) const;
+	template<size_t N> vector_view<event::idx> idxs(event::idx (&)[N]) const;
 	std::tuple<event::id, json::object> auth_events(const size_t &idx) const;
 	event::id auth_event(const size_t &idx) const;
 	bool auth_event_exists(const size_t &idx) const;
@@ -48,3 +50,43 @@ struct ircd::m::event::auth
 	using super_type::tuple;
 	using super_type::operator=;
 };
+
+template<size_t N>
+inline ircd::vector_view<ircd::m::event::idx>
+ircd::m::event::auth::idxs(event::idx (&out)[N])
+const
+{
+	event::id buf[N];
+	const auto &ids
+	{
+		auth::ids(buf)
+	};
+
+	const auto &found
+	{
+		m::index(out, ids)
+	};
+
+	return vector_view<event::idx>
+	(
+		out, out + ids.size()
+	);
+}
+
+template<size_t N>
+inline ircd::vector_view<ircd::m::event::id>
+ircd::m::event::auth::ids(event::id (&out)[N])
+const
+{
+	size_t i(0);
+	m::for_each(*this, [&i, &out](const event::id &event_id)
+	{
+		out[i++] = event_id;
+		return i < N;
+	});
+
+	return vector_view<event::id>
+	(
+		out, i
+	);
+}
diff --git a/include/ircd/m/event/event.h b/include/ircd/m/event/event.h
index f466c2c8c..a0b826e19 100644
--- a/include/ircd/m/event/event.h
+++ b/include/ircd/m/event/event.h
@@ -156,11 +156,11 @@ struct ircd::m::event
 	event() = default;
 };
 
+#include "index.h"
 #include "auth.h"
 #include "prev.h"
 #include "refs.h"
 #include "horizon.h"
-#include "index.h"
 #include "event_id.h"
 #include "fetch.h"
 #include "cached.h"
diff --git a/include/ircd/m/event/prev.h b/include/ircd/m/event/prev.h
index 9acde3595..7772b9298 100644
--- a/include/ircd/m/event/prev.h
+++ b/include/ircd/m/event/prev.h
@@ -44,6 +44,8 @@ struct ircd::m::event::prev
 		20
 	};
 
+	template<size_t N> vector_view<event::id> ids(event::id (&)[N]) const;
+	template<size_t N> vector_view<event::idx> idxs(event::idx (&)[N]) const;
 	std::tuple<event::id, json::object> prev_events(const size_t &idx) const;
 	event::id prev_event(const size_t &idx) const;
 	bool prev_event_exists(const size_t &idx) const;
@@ -55,3 +57,43 @@ struct ircd::m::event::prev
 	using super_type::tuple;
 	using super_type::operator=;
 };
+
+template<size_t N>
+inline ircd::vector_view<ircd::m::event::idx>
+ircd::m::event::prev::idxs(event::idx (&out)[N])
+const
+{
+	event::id buf[N];
+	const auto &ids
+	{
+		prev::ids(buf)
+	};
+
+	const auto &found
+	{
+		m::index(out, ids)
+	};
+
+	return vector_view<event::idx>
+	(
+		out, out + ids.size()
+	);
+}
+
+template<size_t N>
+inline ircd::vector_view<ircd::m::event::id>
+ircd::m::event::prev::ids(event::id (&out)[N])
+const
+{
+	size_t i(0);
+	m::for_each(*this, [&i, &out](const event::id &event_id)
+	{
+		out[i++] = event_id;
+		return i < N;
+	});
+
+	return vector_view<event::id>
+	(
+		out, i
+	);
+}