implement ReadStream

src/fot.rs

@@ -1,6 +1,7 @@
-mod raw;
 mod decoder;
-mod tag;
 mod fstring;
-mod world;
+mod raw;
 pub mod save;
+mod stream;
+mod tag;
+mod world;

src/fot/stream.rs

@@ -0,0 +1,41 @@
+use super::decoder::Decoder;
+use super::raw::Raw;
+use anyhow::Result;
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use std::io::Cursor;
+
+pub struct ReadStream<'a> {
+    raw: &'a Raw,
+    rdr: Cursor<&'a [u8]>,
+}
+
+impl<'a> ReadStream<'a> {
+    fn new(raw: &Raw, offset: usize) -> ReadStream {
+        ReadStream {
+            raw: raw,
+            rdr: Cursor::new(&raw.mem[offset..]),
+        }
+    }
+
+    fn offset(&self) -> usize {
+        self.rdr.position() as usize
+    }
+
+    fn skip(&mut self, size: usize) {
+        self.rdr.set_position(self.rdr.position() + size as u64);
+    }
+
+    fn read<T: Decoder>(&mut self, size: usize) -> Result<T> {
+        let val = T::decode(&self.raw, self.offset(), size)?;
+        self.skip(val.get_enc_size());
+        Ok(val)
+    }
+
+    fn read_u16(&mut self) -> Result<u16> {
+        Ok(self.rdr.read_u16::<LittleEndian>()?)
+    }
+
+    fn read_u32(&mut self) -> Result<u32> {
+        Ok(self.rdr.read_u32::<LittleEndian>()?)
+    }
+}