rename remaining to remaining_slice and add a new remaining

library/std/src/io/cursor.rs

@@ -209,6 +209,32 @@ impl<T> Cursor<T>
 where
     T: AsRef<[u8]>,
 {
+    /// Returns the remaining length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(cursor_remaining)]
+    /// use std::io::Cursor;
+    ///
+    /// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
+    ///
+    /// assert_eq!(buff.remaining(), 5);
+    ///
+    /// buff.set_position(2);
+    /// assert_eq!(buff.remaining(), 3);
+    ///
+    /// buff.set_position(4);
+    /// assert_eq!(buff.remaining(), 1);
+    ///
+    /// buff.set_position(6);
+    /// assert_eq!(buff.remaining(), 0);
+    /// ```
+    #[unstable(feature = "cursor_remaining", issue = "86369")]
+    pub fn remaining(&self) -> u64 {
+        (self.inner.as_ref().len() as u64).checked_sub(self.pos).unwrap_or(0)
+    }
+
     /// Returns the remaining slice.
     ///
     /// # Examples
@@ -219,19 +245,19 @@ where
     ///
     /// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
     ///
-    /// assert_eq!(buff.remaining(), &[1, 2, 3, 4, 5]);
+    /// assert_eq!(buff.remaining_slice(), &[1, 2, 3, 4, 5]);
     ///
     /// buff.set_position(2);
-    /// assert_eq!(buff.remaining(), &[3, 4, 5]);
+    /// assert_eq!(buff.remaining_slice(), &[3, 4, 5]);
     ///
     /// buff.set_position(4);
-    /// assert_eq!(buff.remaining(), &[5]);
+    /// assert_eq!(buff.remaining_slice(), &[5]);
     ///
     /// buff.set_position(6);
-    /// assert_eq!(buff.remaining(), &[]);
+    /// assert_eq!(buff.remaining_slice(), &[]);
     /// ```
     #[unstable(feature = "cursor_remaining", issue = "86369")]
-    pub fn remaining(&self) -> &[u8] {
+    pub fn remaining_slice(&self) -> &[u8] {
         let len = self.pos.min(self.inner.as_ref().len() as u64);
         &self.inner.as_ref()[(len as usize)..]
     }
@@ -324,7 +350,7 @@ where
     T: AsRef<[u8]>,
 {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let n = Read::read(&mut self.remaining(), buf)?;
+        let n = Read::read(&mut self.remaining_slice(), buf)?;
         self.pos += n as u64;
         Ok(n)
     }
@@ -347,7 +373,7 @@ where
 
     fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
         let n = buf.len();
-        Read::read_exact(&mut self.remaining(), buf)?;
+        Read::read_exact(&mut self.remaining_slice(), buf)?;
         self.pos += n as u64;
         Ok(())
     }
@@ -364,7 +390,7 @@ where
     T: AsRef<[u8]>,
 {
     fn fill_buf(&mut self) -> io::Result<&[u8]> {
-        Ok(self.remaining())
+        Ok(self.remaining_slice())
     }
     fn consume(&mut self, amt: usize) {
         self.pos += amt as u64;