From 4af77dfea5290b0053efcb31cad774cabf71af59 Mon Sep 17 00:00:00 2001 From: binarycat Date: Tue, 30 Jul 2024 14:27:20 -0400 Subject: implement BufReader::peek --- library/std/src/io/buffered/bufreader/buffer.rs | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'library/std/src/io/buffered/bufreader/buffer.rs') diff --git a/library/std/src/io/buffered/bufreader/buffer.rs b/library/std/src/io/buffered/bufreader/buffer.rs index 796137c0123..ccd67fafb45 100644 --- a/library/std/src/io/buffered/bufreader/buffer.rs +++ b/library/std/src/io/buffered/bufreader/buffer.rs @@ -97,6 +97,27 @@ impl Buffer { self.pos = self.pos.saturating_sub(amt); } + /// Read more bytes into the buffer without discarding any of its contents + pub fn read_more(&mut self, mut reader: impl Read) -> io::Result<()> { + let mut buf = BorrowedBuf::from(&mut self.buf[self.pos..]); + let old_init = self.initialized - self.pos; + unsafe { + buf.set_init(old_init); + } + reader.read_buf(buf.unfilled())?; + self.filled += buf.len(); + self.initialized += buf.init_len() - old_init; + Ok(()) + } + + /// Remove bytes that have already been read from the buffer. + pub fn backshift(&mut self) { + self.buf.copy_within(self.pos.., 0); + self.initialized -= self.pos; + self.filled -= self.pos; + self.pos = 0; + } + #[inline] pub fn fill_buf(&mut self, mut reader: impl Read) -> io::Result<&[u8]> { // If we've reached the end of our internal buffer then we need to fetch -- cgit 1.4.1-3-g733a5