---
 src/sed/edit.rs | 47 ++++++++++++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/src/sed/edit.rs b/src/sed/edit.rs
index c80cde1..3d11d93 100644
--- a/src/sed/edit.rs
+++ b/src/sed/edit.rs
@@ -20,9 +20,13 @@ use super::parser::parse_substitute;
 use super::types::{Address, Command, Substitute};
 
 use itertools::Itertools;
+use std::borrow::Cow;
 use std::iter::{empty, once, repeat};
 
-fn regex_replace<'a, I>(lines: I, arg: &str) -> Result<String, String>
+fn regex_replace<'a, I>(
+    lines: I,
+    arg: &'a str,
+) -> Result<impl Iterator<Item = Cow<'a, str>>, String>
 where
     I: Iterator<Item = &'a str>,
 {
@@ -31,18 +35,14 @@ where
         replacement,
         flags,
     } = parse_substitute(arg)?;
-    let global = flags.contains('g');
-    let rep: &str = replacement.as_ref();
 
-    let replaced = lines.map(|line| {
-        if global {
-            pattern.replace_all(line, rep)
+    Ok(lines.map(move |line| {
+        if flags.contains('g') {
+            pattern.replace_all(line, &replacement[..])
         } else {
-            pattern.replace(line, rep)
+            pattern.replace(line, &replacement[..])
         }
-    });
-
-    Ok(replaced.collect::<Vec<_>>().join("\n"))
+    }))
 }
 
 pub fn edit(text: &str, cmd: Command) -> Result<String, String> {
@@ -58,24 +58,29 @@ pub fn edit(text: &str, cmd: Command) -> Result<String, String> {
     let editing_range = text.split('\n').skip(start).take(count);
     let repeating_arg = repeat(arg.as_ref()).take(count);
 
-    let tmp;
-    let edited: Box<dyn Iterator<Item = &str>> = match command {
-        'a' => Box::new(editing_range.interleave_shortest(repeating_arg)),
-        'c' => Box::new(once(arg.as_ref())),
+    let edited: Box<dyn Iterator<Item = Cow<'_, str>>> = match command {
+        'a' => Box::new(
+            editing_range
+                .interleave_shortest(repeating_arg)
+                .map(Cow::Borrowed),
+        ),
+        'c' => Box::new(once(arg.as_ref()).map(Cow::Borrowed)),
         'd' => Box::new(empty()),
-        'i' => Box::new(repeating_arg.interleave_shortest(editing_range)),
-        's' => {
-            tmp = regex_replace(editing_range, &arg)?;
-            Box::new(once(tmp.as_ref()))
-        }
+        'i' => Box::new(
+            repeating_arg
+                .interleave_shortest(editing_range)
+                .map(Cow::Borrowed),
+        ),
+        's' => Box::new(regex_replace(editing_range, &arg)?),
         _ => return Err(format!("Sed command `{}` not implemented!", command)),
     };
 
     Ok(text
         .split('\n')
         .take(start)
+        .map(Cow::Borrowed)
         .chain(edited)
-        .chain(text.split('\n').skip(start + count))
-        .intersperse("\n")
+        .chain(text.split('\n').skip(start + count).map(Cow::Borrowed))
+        .intersperse(Cow::Borrowed("\n"))
         .collect())
 }
-- 
2.27.0

Awesome, thanks! This was a real head-scratcher for me, I just
couldn't figure out how to do this this afternoon.

-Hannu