Added Decode/Encode for HashMap<K, V> (#438)

src/features/impl_std.rs

@@ -6,6 +6,7 @@ use crate::{
 };
 use core::time::Duration;
 use std::{
+    collections::HashMap,
     ffi::{CStr, CString},
     io::Read,
     net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
@@ -345,3 +346,35 @@ impl Decode for SocketAddrV6 {
 
 impl std::error::Error for EncodeError {}
 impl std::error::Error for DecodeError {}
+
+impl<K, V> Encode for HashMap<K, V>
+where
+    K: Encode,
+    V: Encode,
+{
+    fn encode<E: Encoder>(&self, mut encoder: E) -> Result<(), EncodeError> {
+        crate::enc::encode_slice_len(&mut encoder, self.len())?;
+        for (k, v) in self.iter() {
+            Encode::encode(k, &mut encoder)?;
+            Encode::encode(v, &mut encoder)?;
+        }
+        Ok(())
+    }
+}
+
+impl<K, V> Decode for HashMap<K, V>
+where
+    K: Decode + Eq + std::hash::Hash,
+    V: Decode,
+{
+    fn decode<D: Decoder>(mut decoder: D) -> Result<Self, DecodeError> {
+        let len = crate::de::decode_slice_len(&mut decoder)?;
+        let mut map = HashMap::with_capacity(len);
+        for _ in 0..len {
+            let k = K::decode(&mut decoder)?;
+            let v = V::decode(&mut decoder)?;
+            map.insert(k, v);
+        }
+        Ok(map)
+    }
+}

src/lib.rs

@@ -15,7 +15,7 @@
 //!
 //! |Name  |Default?|Supported types for Encode/Decode|Enabled methods                                                  |Other|
 //! |------|--------|-----------------------------------------|-----------------------------------------------------------------|-----|
-//! |std   | Yes    ||`decode_from_reader` and `encode_into_writer`|
+//! |std   | Yes    |`HashMap`|`decode_from_reader` and `encode_into_writer`|
 //! |alloc | Yes    |All common containers in alloc, like `Vec`, `String`, `Box`|`encode_to_vec`|
 //! |atomic| Yes    |All `Atomic*` integer types, e.g. `AtomicUsize`, and `AtomicBool`||
 //! |derive| Yes    |||Enables the `BorrowDecode`, `Decode` and `Encode` derive macros|

tests/std.rs

@@ -93,6 +93,12 @@ fn test_std_commons() {
         &*a.read().unwrap() == &*b.read().unwrap()
     });
 
+    let mut map = std::collections::HashMap::new();
+    map.insert("Hello".to_owned(), "world".to_owned());
+    map.insert("How".to_owned(), "are".to_owned());
+    map.insert("you".to_owned(), "doing?".to_owned());
+    the_same(map);
+
     // Borrowed values
     let config = bincode::config::Configuration::standard();
     let mut buffer = [0u8; 1024];