From 434f9c1b3102ef1bbce5f73f17babdbf7b55d974 Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Tue, 2 Apr 2024 12:46:16 -0500
Subject: Implement arity checks

---
 util.lua | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

(limited to 'util.lua')

diff --git a/util.lua b/util.lua
index b5a57b1..d151858 100644
--- a/util.lua
+++ b/util.lua
@@ -7,10 +7,30 @@ function m.pop (tbl)
 	return table.remove(tbl, 1)
 end
 
-function m.arity (r, min, max)
-	--[[ Return whether R is within MIN and MAX (inclusive). ]]
-	local len = #r
-	return len >= min and len <= max
+function m.proc (arity, fn)
+	--[[ Wrap RN in a check that for its ARITY.
+		ARITY can be a number, the minimum number of arguments,
+		or a table {MIN, MAX}.  If MIN is nil or absent, it's 0;
+		if MAX is nil or absent, it's infinity.  MIN and MAX are
+		both inclusive.
+	]]
+	local rmin, rmax, rstr
+	if type(arity) ~= "table" then
+		rmin, rmax = arity, arity
+		rstr = rmin
+	else
+		rmin, rmax = arity[1] or 0, arity[2] or 1/0 -- infinity
+		rstr = rmin .. ".." .. rmax
+	end
+	return function (r)
+		local rlen = r and #r or 0
+		if rlen < rmin or rlen > rmax then
+			error(string.format("Wrong arity: %s, need %s",
+					rlen,
+					rstr))
+		end
+		return fn(r)
+	end
 end
 
 ---
-- 
cgit 1.4.1-21-gabe81