# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1781260719 -3600
# Node ID 7eb0e47418abab87e8d5989830ea610fcfddb1f7
# Parent  75d09be04f130bd513a59f10ae2d736cd7141a79
util.human.io: Add simple version comparison

This is a small helper function that compares version string (it can be passed
to table.sort() as a comparator).

Full version sorts (e.g. semver, and natural/alphanumeric sort in general) are
more complex, and I would like to eventually support those. But this is a
stable branch and we don't need it for anything just yet.

Regarding justification for the stable branch:

The function is being committed with extensive tests, and isn't currently used
anywhere. The plan is to use it in an upcoming update of how TLS profiles are
configured, but the inputs in that case will be fixed (meaning that the risk
of breakage is lower than if we were running it against arbitrary data).

diff -r 75d09be04f13 -r 7eb0e47418ab core/features.lua
--- a/core/features.lua	Sun May 31 11:51:22 2026 +0200
+++ b/core/features.lua	Fri Jun 12 11:38:39 2026 +0100
@@ -37,5 +37,8 @@
 
 		-- SIGUSR1 and 2 events
 		"signal-events";
+
+		-- util.human.io.simple_version_compare
+		"simple-version-compare";
 	};
 };
diff -r 75d09be04f13 -r 7eb0e47418ab spec/util_human_io_spec.lua
--- a/spec/util_human_io_spec.lua	Sun May 31 11:51:22 2026 +0200
+++ b/spec/util_human_io_spec.lua	Fri Jun 12 11:38:39 2026 +0100
@@ -100,6 +100,79 @@
 			return assert.is_nil(human_io.parse_duration_lax("two weeks"), "\"2 weeks\" -> nil");
 		end);
 	end);
+
+	describe("simple_version_compare", function ()
+		local version_compare = human_io.simple_version_compare;
+
+		local function cmp_version(a, b, exp)
+			assert.equal(exp, version_compare(a, b), ("%q < %q"):format(a, b));
+		end
+
+		it("orders versions with differing major numbers", function ()
+			cmp_version("1.0", "2.0", true);
+			cmp_version("2.0", "1.0", false);
+		end);
+
+		it("orders versions with differing minor numbers", function ()
+			cmp_version("1.0", "1.1", true);
+			cmp_version("1.1", "1.0", false);
+		end);
+
+		it("treats a shorter version as less than a longer one sharing the same prefix", function ()
+			cmp_version("1.0", "1.0.1", true);
+			cmp_version("1.0.1", "1.0", false);
+
+			cmp_version("1", "1.0", true);
+			cmp_version("1", "1.1", true);
+
+			cmp_version("1.0.0", "1.0.0.1", true);
+		end);
+
+		it("compares components left-to-right regardless of how many components there are", function ()
+			cmp_version("1.0.1", "1.1", true);
+			cmp_version("1.1", "1.0.1", false);
+
+			cmp_version("1.0.1", "1.1.0", true);
+			cmp_version("1.1.0", "1.0.1", false);
+
+			cmp_version("1.0.0.1", "1.0.1", true);
+		end);
+
+		it("never considers a version less than itself", function ()
+			cmp_version("0", "0", false);
+			cmp_version("1.0", "1.0", false);
+			cmp_version("1.2.3", "1.2.3", false);
+			cmp_version("foo", "foo", false);
+		end);
+
+		it("compares components numerically", function ()
+			cmp_version("1.9", "1.10", true);
+			cmp_version("1.10", "1.9", false);
+
+			cmp_version("1.9.9", "1.10.0", true);
+
+			cmp_version("2.0", "10.0", true);
+			cmp_version("10.0", "2.0", false);
+
+			cmp_version("1.2", "1.10", true);
+
+			cmp_version("1.99", "1.100", true);
+			cmp_version("1.100", "1.99", false);
+		end);
+
+		it("handles leading zeros in numeric components", function ()
+			cmp_version("1.02", "1.10", true);
+			cmp_version("1.10", "1.02", false);
+		end);
+
+		it("treats an empty or non-numeric string as a version with no components", function ()
+			cmp_version("", "1.0", true);
+			cmp_version("1.0", "", false);
+			cmp_version("foo", "1.0", true);
+			cmp_version("1.0", "foo", false);
+			cmp_version("", "", false);
+		end);
+	end);
 end);
 
 
diff -r 75d09be04f13 -r 7eb0e47418ab util/human/io.lua
--- a/util/human/io.lua	Sun May 31 11:51:22 2026 +0200
+++ b/util/human/io.lua	Fri Jun 12 11:38:39 2026 +0100
@@ -222,6 +222,29 @@
 	return tonumber(n) * ( multipliers_lax[m] or 1 );
 end
 
+-- Compares simple version strings (numeric only, not semver compatible)
+-- (can be passed to table.sort)
+local function simple_version_compare(a, b)
+	local a_f, a_s, a_part = a:gmatch("%d+");
+	local b_f, b_s, b_part = b:gmatch("%d+");
+
+	a_part = a_f(a_s, a_part);
+	b_part = b_f(b_s, b_part);
+
+	while a_part and b_part do
+		local an, bn = tonumber(a_part), tonumber(b_part);
+		if an ~= bn then
+			return an < bn;
+		end
+		a_part = a_f(a_s, a_part);
+		b_part = b_f(b_s, b_part);
+	end
+
+	-- return true (a is lower) if b is exhausted
+	-- otherwise, they are equal or b is longer/greater (-> return false)
+	return b_part ~= nil;
+end
+
 return {
 	getchar = getchar;
 	getline = getline;
@@ -237,4 +260,5 @@
 	table = new_table;
 	parse_duration = parse_duration;
 	parse_duration_lax = parse_duration_lax;
+	simple_version_compare = simple_version_compare;
 };