Parsing frames.

Cargo.toml

@@ -12,3 +12,4 @@ tokio = { version = "1.16.1", features = ["full"] }
 dirs = "4.0.0"
 serde_json = "1.0.79"
 serde = { version = "1.0.136", features= ["derive"] }
+bytes = "1.1.0"

src/mpvctl/mod.rs

@@ -1,4 +1,5 @@
 mod command;
+mod mpv_framed;
 mod mpvctl;
 
 pub use mpvctl::MpvCtl;

src/mpvctl/mpv_framed.rs

@@ -0,0 +1,58 @@
+use bytes::{Buf, BytesMut};
+use std::io::{self, Cursor};
+use tokio::{io::AsyncReadExt, net::unix::OwnedReadHalf};
+
+pub struct MpvFramed {
+    buffer: BytesMut,
+    socket_read: OwnedReadHalf,
+}
+
+impl MpvFramed {
+    pub fn new(socket_read: OwnedReadHalf) -> Self {
+        MpvFramed {
+            socket_read,
+            buffer: BytesMut::with_capacity(4 * 1024),
+        }
+    }
+
+    pub async fn read_frame(
+        &mut self,
+    ) -> Result<Option<serde_json::Value>, Box<dyn std::error::Error>> {
+        //
+        todo!()
+    }
+
+    fn parse_frame(&mut self) -> Result<Option<serde_json::Value>, Box<dyn std::error::Error>> {
+        let mut cursor = Cursor::new(&self.buffer[..]);
+        if Self::has_frame(&mut cursor) {
+            let len = cursor.position() as usize;
+            cursor.set_position(0);
+            let frame: serde_json::Value = serde_json::from_slice(&cursor.get_ref()[0..len])?;
+            self.buffer.advance(len);
+            return Ok(Some(frame));
+        }
+        Ok(None)
+    }
+
+    fn has_frame(cursor: &mut Cursor<&[u8]>) -> bool {
+        loop {
+            match Self::next_byte(cursor) {
+                Some(nb) if nb == b'\n' => {
+                    return true;
+                }
+                Some(_) => (),
+                None => {
+                    return false;
+                }
+            };
+        }
+    }
+
+    fn next_byte(cursor: &mut Cursor<&[u8]>) -> Option<u8> {
+        if !cursor.has_remaining() {
+            None
+        } else {
+            Some(cursor.get_u8())
+        }
+    }
+}

src/mpvctl/mpvctl.rs

@@ -1,3 +1,5 @@
+use super::command::Command;
+use bytes::BytesMut;
 use std::collections::HashMap;
 use std::io::Read;
 use std::os::unix::prelude::OsStrExt;
@@ -7,8 +9,6 @@ use tokio::net::unix::OwnedWriteHalf;
 use tokio::net::UnixStream;
 use tokio::sync::oneshot;
 
-use super::command::Command;
-
 pub struct MpvCtl {
     socket: OwnedWriteHalf,
     next_request_id: u64,