add set_nano

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fastdate"
-version = "0.3.5"
+version = "0.3.6"
 edition = "2021"
 description = "Rust fast date carte"
 readme = "Readme.md"

src/datetime.rs

@@ -307,8 +307,8 @@ impl DateTime {
 
     /// stand "0000-00-00 00:00:00.000000000"
     pub fn display_stand(&self) -> String {
-        let mut v =self.display(false);
-        v.replace_range((10..11)," ");
+        let mut v = self.display(false);
+        v.replace_range(10..11, " ");
         v
     }
 
@@ -392,6 +392,15 @@ impl DateTime {
         }
         len
     }
+
+    pub fn set_nano(mut self, nano: u32) -> Self {
+        let v = self.nano();
+        if nano != v {
+            self = self.sub(Duration::from_nanos(v as u64));
+            self = self.add(Duration::from_micros(nano as u64));
+        }
+        self
+    }
 }
 
 impl Add<Duration> for DateTime {

tests/datetime.rs

@@ -355,6 +355,7 @@ fn test_display_datetime() {
     let v = epoch.display(false);
     assert_eq!(v, "2000-01-01T01:01:11.000001233");
 }
+
 #[test]
 fn test_display_stand() {
     let epoch = fastdate::DateTime::from((Date {
@@ -370,3 +371,22 @@ fn test_display_stand() {
     let v = epoch.display_stand();
     assert_eq!(v, "2000-01-01 01:01:11.000001233");
 }
+
+#[test]
+fn test_set_micro() {
+    let mut dt = fastdate::DateTime::from((Date {
+        day: 1,
+        mon: 1,
+        year: 2000,
+    }, Time {
+        nano: 1233,
+        sec: 11,
+        minute: 1,
+        hour: 1,
+    }));
+    dt = dt.set_nano(0);
+    assert_eq!(dt.display_stand(), "2000-01-01 01:01:11");
+
+    dt = dt.set_nano(1);
+    assert_eq!(dt.display_stand(), "2000-01-01 01:01:11.000001");
+}