feat: allow streaming, line-buffered input and output

src/cli.rs

@@ -57,6 +57,10 @@ w - match full words only
     */
     pub flags: Option<String>,
 
+    #[arg(short = 'l', long = "line-buffered", default_value_t = false)]
+    /// Buffered mode. Doesn't support multiline matching
+    pub line_buffered: bool,
+
     /// The regexp or string (if using `-F`) to search for.
     pub find: String,
 

src/main.rs

@@ -8,7 +8,7 @@ use clap::Parser;
 use memmap2::MmapMut;
 use std::{
     fs,
-    io::{stdout, Write},
+    io::{stdout, BufRead, Write},
     ops::DerefMut,
     path::PathBuf,
     process,
@@ -43,6 +43,34 @@ fn try_main() -> Result<()> {
         Source::from_stdin()
     };
 
+    if options.line_buffered && sources == Source::from_stdin() {
+        let stdin = std::io::stdin();
+        let stdout = std::io::stdout();
+        let mut handle = stdout.lock();
+
+        let mut buffer = String::new();
+
+        loop {
+            let mut read_handle = stdin.lock();
+            let bytes_read = read_handle.read_line(&mut buffer)?;
+
+            // .lock()
+            // .read_line(&mut buffer)
+            // .expect("Error reading from standard input");
+            if bytes_read == 0 {
+                break;
+            }
+            let replaced = replacer.replace(buffer.as_bytes());
+            handle
+                .write_all(replaced.as_ref())
+                .expect("Error writing to standard output");
+            handle.flush().expect("Error flushing output");
+            buffer.clear();
+        }
+
+        return Ok(());
+    }
+
     let mut mmaps = Vec::new();
     for source in sources.iter() {
         let mmap = match source {