implement deserialize for event

src/asciicast.rs

@@ -2,9 +2,14 @@
 //!
 //! [asciicast v2]: https://github.com/asciinema/asciinema/blob/develop/doc/asciicast-v2.md
 
-use std::collections::HashMap;
+use std::{collections::HashMap, fmt};
 
-use serde::ser::{Serialize, SerializeSeq, Serializer};
+use serde::{
+  de::{
+    Deserialize, Deserializer, Error as DeError, SeqAccess, Unexpected, Visitor,
+  },
+  ser::{Serialize, SerializeSeq, Serializer},
+};
 
 #[derive(Debug, Builder, Serialize)]
 pub struct Header {
@@ -45,8 +50,14 @@ pub struct Theme {
   palette: String,
 }
 
-pub struct Event(pub f64, pub EventKind);
+#[derive(Debug, Clone, PartialEq)]
+pub struct Event(
+  /// Elapsed time
+  pub f64,
+  pub EventKind,
+);
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub enum EventKind {
   Output(Vec<u8>),
   Input(Vec<u8>),
@@ -72,3 +83,74 @@ impl Serialize for Event {
     seq.end()
   }
 }
+
+impl<'d> Deserialize<'d> for Event {
+  fn deserialize<D>(de: D) -> std::result::Result<Self, D::Error>
+  where
+    D: Deserializer<'d>,
+  {
+    struct Vis;
+    impl<'de> Visitor<'de> for Vis {
+      type Value = Event;
+
+      fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("an array of [timestamp, o or i, data]")
+      }
+
+      fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+      where
+        A: SeqAccess<'de>,
+      {
+        let elapsed: f64 = match seq.next_element()? {
+          Some(v) => v,
+          None => {
+            return Err(A::Error::invalid_length(0, &"an array of length 3"))
+          }
+        };
+
+        let io: char = match seq.next_element()? {
+          Some(v) => v,
+          None => {
+            return Err(A::Error::invalid_length(1, &"an array of length 3"))
+          }
+        };
+
+        // Must first go through &[u8] then to Vec<u8> because serde_json treats
+        // &[u8] specially when it comes to deserializing from binary strings
+        let data = {
+          let data: &'de [u8] = match seq.next_element()? {
+            Some(v) => v,
+            None => {
+              return Err(A::Error::invalid_length(2, &"an array of length 3"))
+            }
+          };
+          data.to_vec()
+        };
+
+        let event_kind = match io {
+          'i' => EventKind::Input(data),
+          'o' => EventKind::Output(data),
+          _ => {
+            return Err(A::Error::invalid_value(
+              Unexpected::Char(io),
+              &"either i or o",
+            ))
+          }
+        };
+
+        Ok(Event(elapsed, event_kind))
+      }
+    }
+
+    de.deserialize_seq(Vis)
+  }
+}
+
+#[test]
+fn test() {
+  let evt = Event(1.5, EventKind::Output(vec![69, 42]));
+  let evt_ser = serde_json::to_string(&evt).unwrap();
+  eprintln!("ser: {evt_ser}");
+  let evt_de: Event = serde_json::from_str(&evt_ser).unwrap();
+  assert_eq!(evt, evt_de);
+}