fix: add get_ref/get_mut/into_inner for noodles-vcf (#211)

* fix: add get_ref/get_mut/into_inner for noodles-vcf

* vcf/async: Fix underlying I/O access examples

* vcf/changelog: Add entries for underlying I/O access

---------

Co-authored-by: Michael Macias <[email protected]>

noodles-vcf/CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## Unreleased
+
+### Added
+
+  * vcf/async: Add common methods to access the underlying I/O:
+    `AsyncReader::get_ref`, `AsyncReader::get_mut`, `AsyncReader::into_inner`,
+    `AsyncWriter::get_ref`, `AsyncWriter::get_mut`, and
+    `AsyncWriter::into_inner`.
+
 ## 0.42.0 - 2023-10-19
 
 ### Changed

noodles-vcf/src/async/reader.rs

@@ -73,6 +73,48 @@ where
         }
     }
 
+    /// Returns a reference to the underlying reader.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let data = [];
+    /// let reader = vcf::AsyncReader::new(&data[..]);
+    /// assert!(reader.get_ref().is_empty());
+    /// ```
+    pub fn get_ref(&self) -> &R {
+        &self.inner
+    }
+
+    /// Returns a mutable reference to the underlying reader.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let data = [];
+    /// let mut reader = vcf::AsyncReader::new(&data[..]);
+    /// assert!(reader.get_mut().is_empty());
+    /// ```
+    pub fn get_mut(&mut self) -> &mut R {
+        &mut self.inner
+    }
+
+    /// Returns the underlying reader.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let data = [];
+    /// let reader = vcf::AsyncReader::new(&data[..]);
+    /// assert!(reader.into_inner().is_empty());
+    /// ```
+    pub fn into_inner(self) -> R {
+        self.inner
+    }
+
     /// Reads the VCF header.
     ///
     /// This reads all header lines prefixed with a `#` (number sign), which includes the header

noodles-vcf/src/async/writer.rs

@@ -28,6 +28,45 @@ where
         Self { inner }
     }
 
+    /// Returns a reference to the underlying writer.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let writer = vcf::AsyncWriter::new(Vec::new());
+    /// assert!(writer.get_ref().is_empty());
+    /// ```
+    pub fn get_ref(&self) -> &W {
+        &self.inner
+    }
+
+    /// Returns a mutable reference to the underlying writer.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let mut writer = vcf::AsyncWriter::new(Vec::new());
+    /// assert!(writer.get_mut().is_empty());
+    /// ```
+    pub fn get_mut(&mut self) -> &mut W {
+        &mut self.inner
+    }
+
+    /// Returns the underlying writer.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_vcf as vcf;
+    /// let writer = vcf::AsyncWriter::new(Vec::new());
+    /// assert!(writer.into_inner().is_empty());
+    /// ```
+    pub fn into_inner(self) -> W {
+        self.inner
+    }
+
     /// Writes a VCF header.
     ///
     /// # Examples