Implement compile_addresses

Author: dspinellis

README.md

@@ -27,6 +27,10 @@ cargo run --release
 ## Extensions
 ### GNU
 * Command-line arguments can be specified in long (`--`) form.
+* Spaces can precede a regular expression modifier.
+
+### BSD and GNU
+* The second address in a range can be specified as a relative address with +N.
 
 ### Other
 * Unicode characters can be specified in regular expression pattern, replacement

src/uu/sed/src/command.rs

@@ -107,6 +107,21 @@ pub struct Command {
     pub next: Option<Box<Command>>, // Pointer to next command
 }
 
+impl Default for Command {
+    fn default() -> Self {
+        Command {
+            code: '_',
+            addr1: None,
+            addr2: None,
+            non_select: false,
+            start_line: Some(0),
+            text: None,
+            data: CommandData::None,
+            next: None,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub enum CommandData {
     None,