Enable non-slice readers

src/de/decoder.rs

@@ -1,4 +1,7 @@
-use super::{read::Reader, Decode};
+use super::{
+    read::{BorrowReader, Reader},
+    BorrowDecode, Decode,
+};
 use crate::{
     config::{Config, Endian, IntEncoding},
     error::DecodeError,
@@ -23,6 +26,12 @@ impl<'de, R: Reader<'de>, C: Config> Decoder<R, C> {
     }
 }
 
+impl<'a, 'de, R: BorrowReader<'de>, C: Config> BorrowDecode<'de> for &'a mut Decoder<R, C> {
+    fn decode_slice(&mut self, len: usize) -> Result<&'de [u8], DecodeError> {
+        self.reader.take_bytes(len)
+    }
+}
+
 impl<'a, 'de, R: Reader<'de>, C: Config> Decode<'de> for &'a mut Decoder<R, C> {
     fn decode_u8(&mut self) -> Result<u8, DecodeError> {
         let mut bytes = [0u8; 1];
@@ -198,10 +207,6 @@ impl<'a, 'de, R: Reader<'de>, C: Config> Decode<'de> for &'a mut Decoder<R, C> {
         })
     }
 
-    fn decode_slice(&mut self, len: usize) -> Result<&'de [u8], DecodeError> {
-        self.reader.forward_read(len, |s| s)
-    }
-
     fn decode_array<const N: usize>(&mut self) -> Result<[u8; N], DecodeError> {
         let mut array = [0u8; N];
         self.reader.read(&mut array)?;

src/de/impls.rs

@@ -1,4 +1,4 @@
-use super::{Decodable, Decode};
+use super::{BorrowDecodable, BorrowDecode, Decodable, Decode};
 use crate::error::DecodeError;
 
 impl<'de> Decodable<'de> for u8 {
@@ -85,16 +85,16 @@ impl<'de> Decodable<'de> for f64 {
     }
 }
 
-impl<'de> Decodable<'de> for &'de [u8] {
-    fn decode<D: Decode<'de>>(mut decoder: D) -> Result<Self, DecodeError> {
+impl<'a, 'de: 'a> BorrowDecodable<'de> for &'a [u8] {
+    fn borrow_decode<D: BorrowDecode<'de>>(mut decoder: D) -> Result<Self, DecodeError> {
         let len = usize::decode(&mut decoder)?;
         decoder.decode_slice(len)
     }
 }
 
-impl<'de> Decodable<'de> for &'de str {
-    fn decode<D: Decode<'de>>(decoder: D) -> Result<Self, DecodeError> {
-        let slice: &[u8] = Decodable::decode(decoder)?;
+impl<'a, 'de: 'a> BorrowDecodable<'de> for &'a str {
+    fn borrow_decode<D: BorrowDecode<'de>>(decoder: D) -> Result<Self, DecodeError> {
+        let slice: &[u8] = BorrowDecodable::borrow_decode(decoder)?;
         core::str::from_utf8(slice).map_err(DecodeError::Utf8)
     }
 }
@@ -171,10 +171,6 @@ where
         T::decode_f64(self)
     }
 
-    fn decode_slice(&mut self, len: usize) -> Result<&'de [u8], DecodeError> {
-        T::decode_slice(self, len)
-    }
-
     fn decode_array<const N: usize>(&mut self) -> Result<[u8; N], DecodeError> {
         T::decode_array::<N>(self)
     }

src/de/mod.rs

@@ -6,10 +6,20 @@ mod impls;
 pub mod read;
 pub use self::decoder::Decoder;
 
-pub trait Decodable<'de>: Sized {
+pub trait Decodable<'de>: Sized + BorrowDecodable<'de> {
     fn decode<D: Decode<'de>>(decoder: D) -> Result<Self, DecodeError>;
 }
 
+pub trait BorrowDecodable<'de>: Sized {
+    fn borrow_decode<D: BorrowDecode<'de>>(decoder: D) -> Result<Self, DecodeError>;
+}
+
+impl<'de, T: Decodable<'de>> BorrowDecodable<'de> for T {
+    fn borrow_decode<D: Decode<'de>>(decoder: D) -> Result<Self, DecodeError> {
+        Decodable::decode(decoder)
+    }
+}
+
 pub trait Decode<'de> {
     fn decode_u8(&mut self) -> Result<u8, DecodeError>;
     fn decode_u16(&mut self) -> Result<u16, DecodeError>;
@@ -27,6 +37,9 @@ pub trait Decode<'de> {
 
     fn decode_f32(&mut self) -> Result<f32, DecodeError>;
     fn decode_f64(&mut self) -> Result<f64, DecodeError>;
-    fn decode_slice(&mut self, len: usize) -> Result<&'de [u8], DecodeError>;
     fn decode_array<const N: usize>(&mut self) -> Result<[u8; N], DecodeError>;
 }
+
+pub trait BorrowDecode<'de>: Decode<'de> {
+    fn decode_slice(&mut self, len: usize) -> Result<&'de [u8], DecodeError>;
+}

src/de/read.rs

@@ -2,9 +2,10 @@ use crate::error::DecodeError;
 
 pub trait Reader<'storage> {
     fn read(&mut self, bytes: &mut [u8]) -> Result<(), DecodeError>;
-    fn forward_read<F, R>(&mut self, length: usize, visitor: F) -> Result<R, DecodeError>
-    where
-        F: Fn(&'storage [u8]) -> R;
+}
+
+pub trait BorrowReader<'storage>: Reader<'storage> {
+    fn take_bytes(&mut self, length: usize) -> Result<&'storage [u8], DecodeError>;
 }
 
 pub struct SliceReader<'storage> {
@@ -40,12 +41,22 @@ impl<'storage> Reader<'storage> for SliceReader<'storage> {
 
         Ok(())
     }
+}
 
+impl<'storage> BorrowReader<'storage> for SliceReader<'storage> {
     #[inline(always)]
-    fn forward_read<F, R>(&mut self, length: usize, visitor: F) -> Result<R, DecodeError>
-    where
-        F: Fn(&'storage [u8]) -> R,
-    {
-        Ok(visitor(self.get_byte_slice(length)?))
+    fn take_bytes(&mut self, length: usize) -> Result<&'storage [u8], DecodeError> {
+        self.get_byte_slice(length)
+    }
+}
+
+#[cfg(feature = "std")]
+impl<'storage, R: std::io::Read> Reader<'storage> for R {
+    #[inline(always)]
+    fn read(&mut self, bytes: &mut [u8]) -> Result<(), DecodeError> {
+        match self.read_exact(bytes) {
+            Ok(_) => Ok(()),
+            Err(_) => Err(DecodeError::UnexpectedEnd),
+        }
     }
 }

src/lib.rs

@@ -43,17 +43,33 @@ pub fn encode_into_slice_with_config<E: enc::Encodeable, C: Config>(
     Ok(encoder.into_writer().bytes_written())
 }
 
-pub fn decode<'__de, D: de::Decodable<'__de>>(
+pub fn decode<'__de, D: de::BorrowDecodable<'__de>>(
     src: &'__de mut [u8],
 ) -> Result<D, error::DecodeError> {
     decode_with_config(src, config::Default)
 }
 
-pub fn decode_with_config<'__de, D: de::Decodable<'__de>, C: Config>(
+pub fn decode_with_config<'__de, D: de::BorrowDecodable<'__de>, C: Config>(
     src: &'__de mut [u8],
     _config: C,
 ) -> Result<D, error::DecodeError> {
     let reader = de::read::SliceReader::new(src);
     let mut decoder = de::Decoder::<_, C>::new(reader, _config);
+    D::borrow_decode(&mut decoder)
+}
+
+#[cfg(feature = "std")]
+pub fn decode_from<'__de, D: de::Decodable<'__de>, R: std::io::Read>(
+    src: &'__de mut R,
+) -> Result<D, error::DecodeError> {
+    decode_from_with_config(src, config::Default)
+}
+
+#[cfg(feature = "std")]
+pub fn decode_from_with_config<'__de, D: de::Decodable<'__de>, C: Config, R: std::io::Read>(
+    src: &'__de mut R,
+    _config: C,
+) -> Result<D, error::DecodeError> {
+    let mut decoder = de::Decoder::<_, C>::new(src, _config);
     D::decode(&mut decoder)
 }