implement ReadSized for HashMap

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bitstream_reader"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["Robin Appelman <robin@icewind.nl>"]
 edition = "2018"
 description = "Reading bit sequences from a byte slice"
@@ -14,4 +14,7 @@ travis-ci = { repository = "icewind1991/bitstream_reader" }
 num-traits = "0.2"
 bitstream_reader_derive = { version = "0.3", path = "bitstream_reader_derive" }
 
+[dev-dependencies]
+maplit = "1.0.1"
+
 [workspace]

src/read.rs

@@ -1,4 +1,6 @@
 use crate::{BitStream, Endianness, Result};
+use std::collections::HashMap;
+use std::hash::Hash;
 
 /// Trait for types that can be read from a stream without requiring the size to be configured
 ///
@@ -269,3 +271,16 @@ impl<E: Endianness, T: BitRead<E>> BitReadSized<E> for Vec<T> {
 //        stream.read_bytes(size)
 //    }
 //}
+
+/// Read `K` and `T` `size` times and return as `HashMap<K, T>`
+impl<E: Endianness, K: BitRead<E> + Eq + Hash, T: BitRead<E>> BitReadSized<E> for HashMap<K, T> {
+    fn read(stream: &mut BitStream<E>, size: usize) -> Result<Self> {
+        let mut map = HashMap::with_capacity(size);
+        for _ in 0..size {
+            let key = stream.read()?;
+            let value = stream.read()?;
+            map.insert(key, value);
+        }
+        Ok(map)
+    }
+}

tests/tests.rs

@@ -1,4 +1,6 @@
 use bitstream_reader::{BigEndian, BitBuffer, BitRead, BitStream, LittleEndian};
+use maplit::hashmap;
+use std::collections::HashMap;
 
 // for bench on nightly
 //use std::fs;
@@ -270,6 +272,12 @@ fn read_sized_trait() {
     stream.set_pos(0).unwrap();
     let vec: Vec<u8> = stream.read_sized(3).unwrap();
     assert_eq!(vec![0b1011_0101, 0b0110_1010, 0b1010_1100], vec);
+    stream.set_pos(0).unwrap();
+    let result: HashMap<u8, u8> = stream.read_sized(2).unwrap();
+    assert_eq!(
+        hashmap!(0b1011_0101 => 0b0110_1010, 0b1010_1100 => 0b1001_1001),
+        result
+    );
 }
 
 #[derive(BitRead, PartialEq, Debug)]