f - no allocations

Author: jkczyz

lightning/src/routing/gossip.rs

@@ -935,20 +935,24 @@ impl fmt::Display for NodeAlias {
 		let control_symbol = core::char::REPLACEMENT_CHARACTER;
 		let first_null = self.0.iter().position(|b| *b == 0).unwrap_or(self.0.len());
 		let bytes = self.0.split_at(first_null).0;
-		let alias = match core::str::from_utf8(bytes) {
+		match core::str::from_utf8(bytes) {
 			Ok(alias) => {
-				alias.chars()
-					.map(|c| if c.is_control() { control_symbol } else { c })
-					.collect::<String>()
+				for c in alias.chars() {
+					let mut bytes = [0u8; 4];
+					let c = if !c.is_control() { c } else { control_symbol };
+					f.write_str(c.encode_utf8(&mut bytes))?;
+				}
 			},
 			Err(_) => {
-				bytes.iter().map(|b| *b as char)
+				for c in bytes.iter().map(|b| *b as char) {
 					// Display printable ASCII characters
-					.map(|c| if c >= '\x20' && c <= '\x7e' { c } else { control_symbol })
-					.collect::<String>()
+					let mut bytes = [0u8; 4];
+					let c = if c >= '\x20' && c <= '\x7e' { c } else { control_symbol };
+					f.write_str(c.encode_utf8(&mut bytes))?;
+				}
 			},
 		};
-		f.write_str(&alias)
+		Ok(())
 	}
 }