add arc impl (#522)

* add arc impl

* ci: trigger

---------

Co-authored-by: Emmanuel Thompson <[email protected]>

Author: vhdirk

src/impls/arc.rs

@@ -0,0 +1,151 @@
+use no_std_io::io::{Read, Seek, Write};
+use std::sync::Arc;
+
+use alloc::vec::Vec;
+
+use crate::ctx::Limit;
+use crate::reader::Reader;
+use crate::writer::Writer;
+use crate::{DekuError, DekuReader, DekuWriter};
+
+impl<'a, T, Ctx> DekuReader<'a, Ctx> for Arc<T>
+where
+    T: DekuReader<'a, Ctx>,
+    Ctx: Copy,
+{
+    fn from_reader_with_ctx<R: Read + Seek>(
+        reader: &mut Reader<R>,
+        inner_ctx: Ctx,
+    ) -> Result<Self, DekuError> {
+        let val = <T>::from_reader_with_ctx(reader, inner_ctx)?;
+        Ok(Arc::new(val))
+    }
+}
+
+impl<'a, T, Ctx, Predicate> DekuReader<'a, (Limit<T, Predicate>, Ctx)> for Arc<[T]>
+where
+    T: DekuReader<'a, Ctx>,
+    Ctx: Copy,
+    Predicate: FnMut(&T) -> bool,
+{
+    fn from_reader_with_ctx<R: Read + Seek>(
+        reader: &mut Reader<R>,
+        (limit, inner_ctx): (Limit<T, Predicate>, Ctx),
+    ) -> Result<Self, DekuError> {
+        // use Vec<T>'s implementation and convert to Arc<[T]>
+        let val = <Vec<T>>::from_reader_with_ctx(reader, (limit, inner_ctx))?;
+        Ok(Arc::from(val.into_boxed_slice()))
+    }
+}
+
+impl<T, Ctx> DekuWriter<Ctx> for Arc<[T]>
+where
+    T: DekuWriter<Ctx>,
+    Ctx: Copy,
+{
+    /// Write all `T`s to bits
+    fn to_writer<W: Write + Seek>(
+        &self,
+        writer: &mut Writer<W>,
+        ctx: Ctx,
+    ) -> Result<(), DekuError> {
+        for v in self.as_ref() {
+            v.to_writer(writer, ctx)?;
+        }
+        Ok(())
+    }
+}
+
+impl<T, Ctx> DekuWriter<Ctx> for Arc<T>
+where
+    T: DekuWriter<Ctx>,
+    Ctx: Copy,
+{
+    /// Write all `T`s to bits
+    fn to_writer<W: Write + Seek>(
+        &self,
+        writer: &mut Writer<W>,
+        ctx: Ctx,
+    ) -> Result<(), DekuError> {
+        self.as_ref().to_writer(writer, ctx)?;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use no_std_io::io::Cursor;
+    use rstest::rstest;
+
+    use super::*;
+    use crate::ctx::*;
+    use crate::native_endian;
+    use crate::reader::Reader;
+    #[cfg(feature = "bits")]
+    use bitvec::prelude::*;
+
+    #[rstest(input, expected,
+        case(
+            &[0xEF, 0xBE],
+            Arc::new(native_endian!(0xBEEF_u16)),
+        ),
+    )]
+    fn test_boxed(input: &[u8], expected: Arc<u16>) {
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let res_read = <Arc<u16>>::from_reader_with_ctx(&mut reader, ()).unwrap();
+        assert_eq!(expected, res_read);
+
+        let mut writer = Writer::new(Cursor::new(vec![]));
+        res_read.to_writer(&mut writer, ()).unwrap();
+        assert_eq!(input.to_vec(), writer.inner.into_inner());
+    }
+
+    // Note: Copied tests from vec.rs impl
+    #[cfg(feature = "bits")]
+    #[rstest(input, endian, bit_size, limit, expected, expected_rest_bits, expected_rest_bytes, expected_write,
+        case::normal_le([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Little, Some(16), 2.into(), Arc::from(vec![0xBBAA, 0xDDCC].into_boxed_slice()), bits![u8, Msb0;], &[], vec![0xAA, 0xBB, 0xCC, 0xDD]),
+        case::normal_be([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Big, Some(16), 2.into(), Arc::from(vec![0xAABB, 0xCCDD].into_boxed_slice()), bits![u8, Msb0;], &[], vec![0xAA, 0xBB, 0xCC, 0xDD]),
+        case::predicate_le([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Little, Some(16), (|v: &u16| *v == 0xBBAA).into(), Arc::from(vec![0xBBAA].into_boxed_slice()), bits![u8, Msb0;], &[0xcc, 0xdd], vec![0xAA, 0xBB]),
+        case::predicate_be([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Big, Some(16), (|v: &u16| *v == 0xAABB).into(), Arc::from(vec![0xAABB].into_boxed_slice()), bits![u8, Msb0;], &[0xcc, 0xdd], vec![0xAA, 0xBB]),
+        case::bytes_le([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Little, Some(16), BitSize(16).into(), Arc::from(vec![0xBBAA].into_boxed_slice()), bits![u8, Msb0;], &[0xcc, 0xdd], vec![0xAA, 0xBB]),
+        case::bytes_be([0xAA, 0xBB, 0xCC, 0xDD].as_ref(), Endian::Big, Some(16), BitSize(16).into(), Arc::from(vec![0xAABB].into_boxed_slice()), bits![u8, Msb0;], &[0xcc, 0xdd], vec![0xAA, 0xBB]),
+    )]
+    fn test_boxed_slice_from_reader_with_ctx<Predicate: FnMut(&u16) -> bool>(
+        input: &[u8],
+        endian: Endian,
+        bit_size: Option<usize>,
+        limit: Limit<u16, Predicate>,
+        expected: Arc<[u16]>,
+        expected_rest_bits: &bitvec::slice::BitSlice<u8, bitvec::prelude::Msb0>,
+        expected_rest_bytes: &[u8],
+        expected_write: Vec<u8>,
+    ) {
+        // Unwrap here because all test cases are `Some`.
+        let bit_size = bit_size.unwrap();
+
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let res_read =
+            <Arc<[u16]>>::from_reader_with_ctx(&mut reader, (limit, (endian, BitSize(bit_size))))
+                .unwrap();
+        assert_eq!(expected, res_read);
+        assert_eq!(
+            reader.rest(),
+            expected_rest_bits.iter().by_vals().collect::<Vec<bool>>()
+        );
+        let mut buf = vec![];
+        cursor.read_to_end(&mut buf).unwrap();
+        assert_eq!(expected_rest_bytes, buf);
+
+        assert_eq!(input[..expected_write.len()].to_vec(), expected_write);
+
+        let mut writer = Writer::new(Cursor::new(vec![]));
+        res_read
+            .to_writer(&mut writer, (endian, BitSize(bit_size)))
+            .unwrap();
+        assert_eq!(expected_write, writer.inner.into_inner());
+
+        assert_eq!(input[..expected_write.len()].to_vec(), expected_write);
+    }
+}

src/impls/mod.rs

@@ -7,6 +7,9 @@ mod tuple;
 mod unit;
 mod vec;
 
+#[cfg(feature = "std")]
+mod arc;
+
 #[cfg(feature = "std")]
 mod cow;