write for entry

examples/producer.rs

@@ -206,7 +206,7 @@ fn main() {
     let mut buf = Vec::new();
     if let Some(out_file_path) = ::std::env::args().nth(1) {
         for node in initial_tree_vec.into_iter() {
-            node.write(&mut buf);
+            node.write(&mut buf).expect("Failed to write data");
         }
 
         let mut file = std::fs::File::create(&out_file_path)

src/entry.rs

@@ -1,4 +1,4 @@
-use byteorder::{LittleEndian, ReadBytesExt};
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 
 use crate::{EntryKind, NodeData, Error, EntryLink, MAX_NODE_DATA_SIZE};
 
@@ -67,6 +67,24 @@ impl Entry {
         })
     }
 
+    pub fn write<W: std::io::Write>(&self, w: &mut W) -> std::io::Result<()> {
+        match self.kind {
+            EntryKind::Node(EntryLink::Stored(left), EntryLink::Stored(right)) => {
+                w.write_u8(0)?;
+                w.write_u32::<LittleEndian>(left)?;
+                w.write_u32::<LittleEndian>(right)?;
+            },
+            EntryKind::Leaf => {
+                w.write_u8(1)?;
+            },
+            _ => { return Err(std::io::Error::from(std::io::ErrorKind::InvalidData)); }
+        }
+
+        self.data.write(w)?;
+
+        Ok(())
+    }
+
     pub fn from_bytes<T: AsRef<[u8]>>(consensus_branch_id: u32, buf: T) -> std::io::Result<Self> {
         let mut cursor = std::io::Cursor::new(buf);
         Self::read(consensus_branch_id, &mut cursor)