From 7bcaa341b8685ba411d206c1a89dc3ca77aa71bb Mon Sep 17 00:00:00 2001
From: Max Verevkin <maxxverrr@gmail.com>
Date: Fri, 1 Apr 2022 21:50:19 +0300
Subject: initial commit

---
 src/lines_buffer.rs | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 src/lines_buffer.rs

(limited to 'src/lines_buffer.rs')

diff --git a/src/lines_buffer.rs b/src/lines_buffer.rs
new file mode 100644
index 0000000..7813ea2
--- /dev/null
+++ b/src/lines_buffer.rs
@@ -0,0 +1,54 @@
+use std::borrow::Cow;
+use std::io::{BufRead, BufReader, Read, Result};
+
+pub struct LinesBuffer<R> {
+    reader: BufReader<R>,
+    next_line: Vec<u8>,
+}
+
+impl<R: Read> LinesBuffer<R> {
+    pub fn new(inner: R) -> Self {
+        Self {
+            reader: BufReader::new(inner),
+            next_line: Vec::new(),
+        }
+    }
+
+    pub fn fill_buf(&mut self) -> Result<()> {
+        self.reader.fill_buf()?;
+        Ok(())
+    }
+
+    pub fn inner(&self) -> &R {
+        self.reader.get_ref()
+    }
+}
+
+impl<R: Read> Iterator for &mut LinesBuffer<R> {
+    type Item = String;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let pending = self.reader.buffer();
+        let (result, used) = match memchr::memchr(b'\n', pending) {
+            None => {
+                self.next_line.extend_from_slice(pending);
+                (None, pending.len())
+            }
+            Some(i) => {
+                self.next_line.extend_from_slice(&pending[..i]);
+                let line = from_utf8(&self.next_line);
+                self.next_line.clear();
+                (Some(line), i + 1)
+            }
+        };
+        self.reader.consume(used);
+        result
+    }
+}
+
+fn from_utf8(bytes: &[u8]) -> String {
+    match String::from_utf8_lossy(bytes) {
+        Cow::Borrowed(s) => s.to_owned(),
+        Cow::Owned(s) => s,
+    }
+}
-- 
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