on the way to a usable version

src/utils.rs

@@ -1,13 +1,25 @@
 // SPDX-License-Identifier: GPL-3.0-only
+
+use crate::reader::AheadReader;
+
+use std::io::BufReader;
 use std::{
     fs::File,
-    io::{self, Read, Write},
+    io::{self, Write},
 };
 
-pub(crate) fn read_from_file_or_stdin<S: AsRef<str>>(input_file: Option<S>) -> Box<dyn Read> {
+pub const BUFSIZE: usize = 64 * 1024; // 64 KiB
+
+pub(crate) fn read_from_file_or_stdin<S: AsRef<str>>(
+    input_file: Option<S>,
+    bufsz: usize,
+) -> AheadReader {
     match input_file {
-        Some(f) => Box::new(File::open(f.as_ref()).unwrap()),
-        None => Box::new(io::stdin()),
+        Some(f) => AheadReader::from(
+            Box::new(BufReader::new(File::open(f.as_ref()).unwrap())),
+            bufsz,
+        ),
+        None => AheadReader::from(Box::new(io::stdin().lock()), bufsz),
     }
 }