make update_reader/mmap/mmap_rayon return self

This makes them consistent with how the existing update() and
update_rayon() methods work, with the difference being that it's it's
io::Result<&mut Self> instead of just &mut Self.

src/lib.rs

@@ -1346,8 +1346,9 @@ impl Hasher {
     /// # }
     /// ```
     #[cfg(feature = "std")]
-    pub fn update_reader(&mut self, reader: impl std::io::Read) -> std::io::Result<u64> {
-        io::copy_wide(reader, self)
+    pub fn update_reader(&mut self, reader: impl std::io::Read) -> std::io::Result<&mut Self> {
+        io::copy_wide(reader, self)?;
+        Ok(self)
     }
 
     /// As [`update`](Hasher::update), but using Rayon-based multithreading
@@ -1417,14 +1418,14 @@ impl Hasher {
     /// # }
     /// ```
     #[cfg(feature = "mmap")]
-    pub fn update_mmap(&mut self, path: impl AsRef<std::path::Path>) -> std::io::Result<()> {
+    pub fn update_mmap(&mut self, path: impl AsRef<std::path::Path>) -> std::io::Result<&mut Self> {
         let file = std::fs::File::open(path.as_ref())?;
         if let Some(mmap) = io::maybe_mmap_file(&file)? {
             self.update(&mmap);
         } else {
             io::copy_wide(&file, self)?;
         }
-        Ok(())
+        Ok(self)
     }
 
     /// As [`update_rayon`](Hasher::update_rayon), but reading the contents of a file using
@@ -1469,14 +1470,17 @@ impl Hasher {
     /// ```
     #[cfg(feature = "mmap")]
     #[cfg(feature = "rayon")]
-    pub fn update_mmap_rayon(&mut self, path: impl AsRef<std::path::Path>) -> std::io::Result<()> {
+    pub fn update_mmap_rayon(
+        &mut self,
+        path: impl AsRef<std::path::Path>,
+    ) -> std::io::Result<&mut Self> {
         let file = std::fs::File::open(path.as_ref())?;
         if let Some(mmap) = io::maybe_mmap_file(&file)? {
             self.update_rayon(&mmap);
         } else {
             io::copy_wide(&file, self)?;
         }
-        Ok(())
+        Ok(self)
     }
 }
 

src/test.rs

@@ -701,9 +701,12 @@ fn test_update_reader() -> Result<(), std::io::Error> {
     let mut tempfile = tempfile::NamedTempFile::new()?;
     tempfile.write_all(&input)?;
     tempfile.flush()?;
-    let mut hasher = crate::Hasher::new();
-    hasher.update_reader(std::fs::File::open(tempfile.path())?)?;
-    assert_eq!(hasher.finalize(), crate::hash(&input));
+    assert_eq!(
+        crate::Hasher::new()
+            .update_reader(std::fs::File::open(tempfile.path())?)?
+            .finalize(),
+        crate::hash(&input),
+    );
     Ok(())
 }
 
@@ -755,9 +758,12 @@ fn test_mmap() -> Result<(), std::io::Error> {
     let mut tempfile = tempfile::NamedTempFile::new()?;
     tempfile.write_all(&input)?;
     tempfile.flush()?;
-    let mut hasher = crate::Hasher::new();
-    hasher.update_mmap(tempfile.path())?;
-    assert_eq!(hasher.finalize(), crate::hash(&input));
+    assert_eq!(
+        crate::Hasher::new()
+            .update_mmap(tempfile.path())?
+            .finalize(),
+        crate::hash(&input),
+    );
     Ok(())
 }
 
@@ -792,8 +798,11 @@ fn test_mmap_rayon() -> Result<(), std::io::Error> {
     let mut tempfile = tempfile::NamedTempFile::new()?;
     tempfile.write_all(&input)?;
     tempfile.flush()?;
-    let mut hasher = crate::Hasher::new();
-    hasher.update_mmap_rayon(tempfile.path())?;
-    assert_eq!(hasher.finalize(), crate::hash(&input));
+    assert_eq!(
+        crate::Hasher::new()
+            .update_mmap_rayon(tempfile.path())?
+            .finalize(),
+        crate::hash(&input),
+    );
     Ok(())
 }