iter: Replace some map(..).flatten() with and_then(..)

Signed-off-by: Kristofer Rye <kristofer.rye@gmail.com>

Author: rye

src/iter/address.rs

@@ -34,7 +34,7 @@ where
 	/// may produce `None`.
 	fn next(&mut self) -> Option<Self::Item> {
 		let cur: Option<Self::Item> = self.cur;
-		let next: Option<Self::Item> = cur.map(|cur| cur.offset(1_u32)).flatten();
+		let next: Option<Self::Item> = cur.and_then(|cur| cur.offset(1_u32));
 
 		match (cur, next) {
 			(Some(cur), Some(next)) => {

src/iter/offset.rs

@@ -24,11 +24,10 @@ impl Offset<i32> for Ipv6Addr {
 
 		// This is a simple "if positive, use checked_add, if negative, use checked_sub" conditional
 		offset_abs
-			.map(|abs: u128| match offset {
+			.and_then(|abs: u128| match offset {
 				0..=MAX => u128::from(*self).checked_add(abs),
 				MIN..=-1 => u128::from(*self).checked_sub(abs),
 			})
-			.flatten()
 			.map(Ipv6Addr::from)
 	}
 }
@@ -53,8 +52,7 @@ impl Offset<i32> for Ipv4Addr {
 		let offset: Option<u32> = addr
 			.checked_add(i64::from(offset))
 			.map(TryInto::try_into)
-			.map(Result::ok)
-			.flatten();
+			.and_then(Result::ok);
 		offset.map(Ipv4Addr::from)
 	}
 }
@@ -63,8 +61,7 @@ impl Offset<u128> for Ipv4Addr {
 	fn offset(&self, offset: u128) -> Option<Self> {
 		let offset: Option<u32> = offset.try_into().ok();
 		offset
-			.map(|offset: u32| u32::from(*self).checked_add(offset))
-			.flatten()
+			.and_then(|offset: u32| u32::from(*self).checked_add(offset))
 			.map(Ipv4Addr::from)
 	}
 }

src/iter/subnet.rs

@@ -19,9 +19,8 @@ impl Iterator for SubnetIterator<Netv4Addr, Netv4Addr> {
 			Some(cur) if self.net.contains(&cur) => {
 				let device_count: Option<u32> = cur.len();
 
-				let next: Option<Netv4Addr> = device_count
-					.map(|device_count: u32| cur.offset(device_count))
-					.flatten();
+				let next: Option<Netv4Addr> =
+					device_count.and_then(|device_count: u32| cur.offset(device_count));
 
 				match next {
 					Some(next) => {
@@ -56,9 +55,8 @@ impl Iterator for SubnetIterator<Netv6Addr, Netv6Addr> {
 			Some(cur) if self.net.contains(&cur) => {
 				let device_count: Option<u128> = cur.len();
 
-				let next: Option<Netv6Addr> = device_count
-					.map(|device_count: u128| cur.offset(device_count))
-					.flatten();
+				let next: Option<Netv6Addr> =
+					device_count.and_then(|device_count: u128| cur.offset(device_count));
 
 				match next {
 					Some(next) => {