More cleanup

core/src/buffer_view.rs

@@ -0,0 +1,70 @@
+use std::fmt::Debug;
+use crate::error::ErrorKind;
+
+pub(crate) struct BufferView<'a> {
+    inner: &'a [u8],
+    consumed: usize,
+}
+
+impl Debug for BufferView<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:?}", &self.inner[self.consumed..])
+    }
+}
+
+impl BufferView<'_> {
+    pub fn new(inner: &'_ [u8]) -> BufferView<'_> {
+        BufferView { inner, consumed: 0 }
+    }
+
+    pub fn consume_into_u32(&mut self) -> Result<u32, ErrorKind> {
+        if self.consumed + 4 > self.inner.len() {
+            return Err(ErrorKind::IncompleteData);
+        }
+        let res = u32::from_be_bytes(
+            self.inner[self.consumed..self.consumed + 4]
+                .try_into()
+                .unwrap(),
+        );
+        self.consumed += 4;
+        Ok(res)
+    }
+
+    pub fn consume_into_u16(&mut self) -> Result<u16, ErrorKind> {
+        if self.consumed + 2 > self.inner.len() {
+            return Err(ErrorKind::IncompleteData);
+        }
+        let res = u16::from_be_bytes(
+            self.inner[self.consumed..self.consumed + 2]
+                .try_into()
+                .unwrap(),
+        );
+        self.consumed += 2;
+        Ok(res)
+    }
+
+    pub fn consume_into_vec_n(&mut self, n: usize) -> Result<Vec<u8>, ErrorKind> {
+        if self.consumed + n > self.inner.len() {
+            return Err(ErrorKind::IncompleteData);
+        }
+        let data = self.inner[self.consumed..self.consumed + n].to_vec();
+        self.consumed += n;
+        if data.len() != n {
+            return Err(ErrorKind::IncompleteData);
+        }
+        Ok(data)
+    }
+
+    pub fn remaining(&self) -> usize {
+        self.inner.len() - self.consumed
+    }
+
+    pub fn consumed(&self) -> usize {
+        self.consumed
+    }
+
+    pub fn swallow(&mut self, n: usize) {
+        self.consumed += n;
+    }
+}
+