From 1f8c95ba28a59bf8459a15c8b2d52234e577e191 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Fri, 29 Aug 2014 14:56:13 -0400
Subject: [PATCH] luatz/timetable: Optimize and export `is_leap`; add tests

---
 luatz/timetable.lua     |  9 ++++++++-
 spec/timetable_spec.lua | 13 +++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/luatz/timetable.lua b/luatz/timetable.lua
index f096372..99ac52e 100644
--- a/luatz/timetable.lua
+++ b/luatz/timetable.lua
@@ -16,7 +16,13 @@ end
 local sakamoto = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
 
 local function is_leap ( y )
-	return (y % 4) == 0 and (y % 100) ~= 0 or (y % 400) == 0
+	if (y % 4) ~= 0 then
+		return false
+	elseif (y % 100) ~= 0 then
+		return true
+	else
+		return (y % 400) == 0
+	end
 end
 
 local function year_length ( y )
@@ -200,6 +206,7 @@ local function new_from_timestamp ( ts )
 end
 
 return {
+	is_leap = is_leap ;
 	day_of_year = day_of_year ;
 	day_of_week = day_of_week ;
 	normalise = normalise ;
diff --git a/spec/timetable_spec.lua b/spec/timetable_spec.lua
index b769911..0ff42b1 100644
--- a/spec/timetable_spec.lua
+++ b/spec/timetable_spec.lua
@@ -9,6 +9,19 @@ describe ( "Timetable library" , function ( )
 		})
 	end
 
+	it ( "#is_leap is correct" , function ( )
+		assert.same ( false , timetable.is_leap ( 1 ) )
+		assert.same ( false , timetable.is_leap ( 3 ) )
+		assert.same ( true  , timetable.is_leap ( 4 ) )
+		assert.same ( true  , timetable.is_leap ( 2000 ) )
+		assert.same ( true  , timetable.is_leap ( 2004 ) )
+		assert.same ( true  , timetable.is_leap ( 2012 ) )
+		assert.same ( false , timetable.is_leap ( 2013 ) )
+		assert.same ( false , timetable.is_leap ( 2014 ) )
+		assert.same ( false , timetable.is_leap ( 2100 ) )
+		assert.same ( true  , timetable.is_leap ( 2400 ) )
+	end )
+
 	it ( "#normalise gets #wday (day of week) correct" , function ( )
 
 		local function assert_same_wday ( year , month , day )
-- 
2.39.2