feat: Introduce the SharedDataCursor type

src/shared_data_cursor.rs

@@ -0,0 +1,45 @@
+use std::io::{self, Read, Cursor, BufRead};
+use std::sync::Arc;
+use crate::data::SharedData;
+
+pub struct SharedDataCursor(Cursor<SharedData>);
+
+impl SharedDataCursor {
+    pub fn from_bytes(bytes: Vec<u8>) -> SharedDataCursor {
+        let len = bytes.len();
+        let bytes = Arc::new(bytes);
+
+        SharedDataCursor::from_shared_bytes(bytes, 0, len)
+    }
+
+    pub fn from_shared_bytes(bytes: Arc<Vec<u8>>, offset: usize, len: usize) -> SharedDataCursor {
+        let data = SharedData::new(bytes, offset, len);
+        let cursor = Cursor::new(data);
+
+        SharedDataCursor(cursor)
+    }
+
+    pub fn extract(&mut self, amt: usize) -> SharedData {
+        let offset = self.0.position() as usize;
+        let extracted = self.0.get_ref().range(offset, amt);
+        self.0.consume(amt);
+
+        extracted
+    }
+}
+
+impl Read for SharedDataCursor {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.read(buf)
+    }
+}
+
+impl BufRead for SharedDataCursor {
+    fn fill_buf(&mut self) -> io::Result<&[u8]> {
+        self.0.fill_buf()
+    }
+
+    fn consume(&mut self, amt: usize) {
+        self.0.consume(amt)
+    }
+}