bencode encoding

src/bencode/encode.rs

@@ -0,0 +1,73 @@
+use std::borrow::Borrow;
+use std::collections::BTreeMap;
+
+use bencode::Object;
+
+pub fn encode<B>(obj: B) -> Vec<u8> where B: Borrow<Object> {
+    let mut buff = Vec::new();
+    encode_object(&mut buff, obj.borrow());
+    buff
+}
+
+fn encode_object(buff: &mut Vec<u8>, obj: &Object) {
+    match *obj {
+        Object::Int(num) => encode_int(buff, num),
+        Object::Bytes(ref bytes) => encode_bytes(buff, bytes),
+        Object::List(ref list) => encode_list(buff, list),
+        Object::Dict(ref dict) => encode_dict(buff, dict),
+    }
+}
+
+fn encode_int(buff: &mut Vec<u8>, num: i64) {
+    buff.extend_from_slice(format!("i{}e", num).as_bytes());
+}
+
+fn encode_bytes(buff: &mut Vec<u8>, bytes: &[u8]) {
+    buff.extend_from_slice(format!("{}:", bytes.len()).as_bytes());
+    buff.extend_from_slice(bytes);
+}
+
+fn encode_list(buff: &mut Vec<u8>, list: &[Object]) {
+    buff.push(b'l');
+    for obj in list {
+        encode_object(buff, obj);
+    }
+    buff.push(b'e');
+}
+
+fn encode_dict(buff: &mut Vec<u8>, dict: &BTreeMap<Vec<u8>, Object>) {
+    buff.push(b'd');
+    for (key, val) in dict {
+        encode_bytes(buff, key);
+        encode_object(buff, val);
+    }
+    buff.push(b'e');
+}
+
+#[test]
+fn test_int_pos() {
+    assert_eq!(encode(Object::Int(1337)), b"i1337e");
+}
+
+#[test]
+fn test_int_neg() {
+    assert_eq!(encode(Object::Int(-1337)), b"i-1337e");
+}
+
+#[test]
+fn test_bytes() {
+    assert_eq!(encode(Object::Bytes(b"hello".to_vec())), b"5:hello");
+}
+
+#[test]
+fn test_list() {
+    let list = vec![Object::Int(1), Object::Int(2), Object::Int(3)];
+    assert_eq!(encode(Object::List(list)), b"li1ei2ei3ee");
+}
+
+#[test]
+fn test_dict() {
+    let mut dict = BTreeMap::new();
+    dict.insert(b"hello".to_vec(), Object::Int(1337));
+    assert_eq!(encode(Object::Dict(dict)), b"d5:helloi1337ee")
+}