From f9c7e46a347576c9327aaa0d9b6a5b4cd07c26e2 Mon Sep 17 00:00:00 2001
From: HybridDog <3192173+HybridDog@users.noreply.github.com>
Date: Sat, 4 Jan 2020 15:44:48 +0100
Subject: [PATCH] Add table.key_value_swap (#9248)

---
 builtin/common/misc_helpers.lua | 9 +++++++++
 doc/lua_api.txt                 | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
index 88a498927..199f13cd1 100644
--- a/builtin/common/misc_helpers.lua
+++ b/builtin/common/misc_helpers.lua
@@ -575,6 +575,15 @@ function table.insert_all(t, other)
 end
 
 
+function table.key_value_swap(t)
+	local ti = {}
+	for k,v in pairs(t) do
+		ti[v] = k
+	end
+	return ti
+end
+
+
 --------------------------------------------------------------------------------
 -- mainmenu only functions
 --------------------------------------------------------------------------------
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 35be95d51..374a774b1 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -2902,6 +2902,8 @@ Helper functions
 * `table.insert_all(table, other_table)`:
     * Appends all values in `other_table` to `table` - uses `#table + 1` to
       find new indices.
+* `table.key_value_swap(t)`: returns a table with keys and values swapped
+    * If multiple keys in `t` map to the same value, the result is undefined.
 * `minetest.pointed_thing_to_face_pos(placer, pointed_thing)`: returns a
   position.
     * returns the exact position on the surface of a pointed node