Add native-endian methods to BinWrite API

Refs #326.

Author: csnover

binrw/src/binwrite/mod.rs

@@ -86,6 +86,19 @@ pub trait BinWrite {
         self.write_le_args(writer, Self::Args::args())
     }
 
+    /// Write `Self` to the writer assuming native-endian byte order.
+    ///
+    /// # Errors
+    ///
+    /// If writing fails, an [`Error`](crate::Error) variant will be returned.
+    #[inline]
+    fn write_ne<W: Write + Seek>(&self, writer: &mut W) -> BinResult<()>
+    where
+        for<'a> Self::Args<'a>: Required,
+    {
+        self.write_ne_args(writer, Self::Args::args())
+    }
+
     /// Write `Self` to the writer using the given arguments.
     ///
     /// # Errors
@@ -129,6 +142,21 @@ pub trait BinWrite {
         self.write_options(writer, Endian::Little, args)
     }
 
+    /// Write `Self` to the writer, assuming native-endian byte order, using the
+    /// given arguments.
+    ///
+    /// # Errors
+    ///
+    /// If reading fails, an [`Error`](crate::Error) variant will be returned.
+    #[inline]
+    fn write_ne_args<W: Write + Seek>(
+        &self,
+        writer: &mut W,
+        args: Self::Args<'_>,
+    ) -> BinResult<()> {
+        self.write_options(writer, Endian::NATIVE, args)
+    }
+
     /// Write `Self` to the writer using the given [`Endian`] and
     /// arguments.
     ///

binrw/tests/binwrite_impls.rs

@@ -75,6 +75,30 @@ fn non_zero() {
     );
 }
 
+#[test]
+fn native_endian() {
+    #[derive(BinWrite)]
+    struct Test(u16);
+
+    #[derive(BinWrite)]
+    #[bw(import(mul: u16))]
+    struct TestArgs(#[bw(map = |val| mul * *val)] u16);
+
+    let mut output = binrw::io::Cursor::new(vec![]);
+    Test(1).write_ne(&mut output).unwrap();
+    #[cfg(target_endian = "big")]
+    assert_eq!(output.into_inner(), b"\0\x01");
+    #[cfg(target_endian = "little")]
+    assert_eq!(output.into_inner(), b"\x01\0");
+
+    let mut output = binrw::io::Cursor::new(vec![]);
+    TestArgs(2).write_ne_args(&mut output, (2,)).unwrap();
+    #[cfg(target_endian = "big")]
+    assert_eq!(output.into_inner(), b"\0\x04");
+    #[cfg(target_endian = "little")]
+    assert_eq!(output.into_inner(), b"\x04\0");
+}
+
 #[test]
 fn option() {
     compare!(Some(1_i32), Endian::Big, b"\0\0\0\x01");