From d4c3b70d6290c52f903e674e9957b979abd4ce07 Mon Sep 17 00:00:00 2001
From: lamp
Date: Sun, 5 Mar 2023 21:37:45 +0000
Subject: init

---
 src/peekable_bufreader.rs | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 src/peekable_bufreader.rs

(limited to 'src/peekable_bufreader.rs')

diff --git a/src/peekable_bufreader.rs b/src/peekable_bufreader.rs
new file mode 100644
index 0000000..ae02155
--- /dev/null
+++ b/src/peekable_bufreader.rs
@@ -0,0 +1,47 @@
+use async_std::prelude::*;
+use async_std::io::BufReader;
+use async_std::io::Read;
+
+pub struct PeekableBufReader<T>
+    where T: Read + Unpin {
+    reader: BufReader<T>,
+    buffer: [u8; 1],
+    peeked_last: bool,
+}
+
+impl<T> PeekableBufReader<T>
+    where T: Read + Unpin {
+    pub fn new(reader: BufReader<T>) -> Self {
+        Self {
+            reader,
+            buffer: [0],
+            peeked_last: false,
+        }
+    }
+
+    pub async fn next(&mut self) -> Option<u8> {
+        if self.peeked_last {
+            self.peeked_last = false;
+            Some(self.buffer[0])
+        } else {
+            match self.reader.read(&mut self.buffer).await.ok()? {
+                1 => Some(self.buffer[0]),
+                _ => None,
+            }
+        }
+    }
+
+    pub async fn peek(&mut self) -> Option<&u8> {
+        if self.peeked_last {
+            Some(&self.buffer[0])
+        } else {
+            match self.reader.read(&mut self.buffer).await.ok()? {
+                1 => {
+                    self.peeked_last = true;
+                    Some(&self.buffer[0])
+                },
+                _ => None,
+            }
+        }
+    }
+}
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