got some serious performance improvement from once_cell!!!!

3 files changed, 8 insertions, 2 deletions

diff --git a/src/lib.rs b/src/lib.rs
index e8eb2af..8086a17 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 extern crate chrono;
+extern crate once_cell;
 
 pub mod datetime;
 pub mod iter;
diff --git a/src/masks.rs b/src/masks.rs
index 3b609b4..2ae7941 100644
--- a/src/masks.rs
+++ b/src/masks.rs
@@ -1,9 +1,14 @@
+use once_cell::sync::Lazy;
+
 // =============================================================================
 // Date masks
 // =============================================================================
 
 // Every mask is 7 days longer to handle cross-year weekly periods.
 
+pub static MASKS: Lazy<Masks> = Lazy::new(|| Masks::new());
+
+#[derive(Clone)]
 pub struct Masks {
     pub WDAY: Vec<usize>,
     pub M365: Vec<usize>,
diff --git a/src/yearinfo.rs b/src/yearinfo.rs
index 19a21a6..08aad23 100644
--- a/src/yearinfo.rs
+++ b/src/yearinfo.rs
@@ -1,4 +1,4 @@
-use crate::masks::Masks;
+use crate::masks::MASKS;
 use crate::options::*;
 use chrono::prelude::*;
 use chrono::{DateTime, Duration};
@@ -39,7 +39,7 @@ pub struct BaseMasks {
 }
 
 fn base_year_masks(year: i32) -> BaseMasks {
-    let masks = Masks::new();
+    let masks = MASKS.clone();
     let firstyday = Utc.ymd(year, 1, 1).and_hms_milli(0, 0, 0, 0);
     let yearlen = get_year_len(year);
     let wday = get_weekday_val(&firstyday.weekday()) as usize;