events: implement a first attempt at an eventing system

src/events.rs

@@ -0,0 +1,163 @@
+use core::fmt::Debug;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum InputEvent {
+    PowerOn,
+    PowerOff,
+    NetworkActivity,
+    NetworkOnline,
+    NetworkOffline
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Variant {
+    Byte(u8),
+    UInt(u32),
+    Int(i32),
+    BigUInt(u64),
+    BigInt(i64),
+    Boolean(bool)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Event {
+    ReadyToRock,
+    Tick,
+    StartThing(&'static str),
+    StopThing(&'static str),
+    Input(InputEvent),
+    PropertyChange(&'static str, Variant)
+}
+
+pub struct SystemState {
+    key: &'static str,
+    value: Variant,
+    values: Vec::<Box<SystemState>>
+}
+
+impl SystemState {
+    pub fn new() -> Self {
+        SystemState {
+            key: "",
+            value: Variant::Byte(0),
+            values: Vec::new()
+        }
+    }
+
+    fn get_key(&self, key: &'static str) -> Option<&Self> {
+        if key == self.key {
+            Some(self)
+        } else {
+            for next in self.values.iter() {
+                match next.get_key(key) {
+                    None => (),
+                    Some(next_val) => return Some(next_val)
+                }
+            }
+            return None
+        }
+    }
+
+    fn get_key_mut(&mut self, key: &'static str) -> Option<&mut Self> {
+        if key == self.key {
+            Some(self)
+        } else {
+            for next in self.values.iter_mut() {
+                match next.get_key_mut(key) {
+                    None => (),
+                    Some(next_val) => return Some(next_val)
+                }
+            }
+            return None
+        }
+    }
+
+    pub fn get(&self, key: &'static str) -> Option<Variant> {
+        match self.get_key(key) {
+            None => None,
+            Some(v) => Some(v.value)
+        }
+    }
+
+    pub fn set<V>(&mut self, key: &'static str, value: V) where Variant: From<V> {
+        match self.get_key_mut(key) {
+            None => self.values.push(Box::new(SystemState {
+                value: value.into(),
+                key: key,
+                values: Vec::new()
+            })),
+            Some(found_key) => {
+                found_key.value = value.into()
+            }
+        }
+    }
+}
+
+impl Event {
+    pub fn new_tick() -> Self {
+        Event::Tick
+    }
+
+    pub fn new_property_change<T>(key: &'static str, data: T) -> Self where Variant: From<T> {
+        Event::PropertyChange(key, Variant::from(data))
+    }
+
+    pub fn new_ready_to_rock() -> Self {
+        Event::ReadyToRock
+    }
+
+    pub fn new_input_event(event: InputEvent) -> Self {
+        Event::Input(event)
+    }
+}
+
+impl Into<u8> for Variant {
+    fn into(self) -> u8 {
+        match self {
+            Variant::Byte(b) => b,
+            _ => 0
+        }
+    }
+}
+
+impl From<bool> for Variant {
+    fn from(value: bool) -> Self {
+        Variant::Boolean(value)
+    }
+}
+
+impl From<i64> for Variant {
+    fn from(value: i64) -> Self {
+        Variant::BigInt(value)
+    }
+}
+
+impl From<u8> for Variant {
+    fn from(value: u8) -> Self {
+        Variant::Byte(value)
+    }
+}
+
+pub struct EventBus {
+    pending: Vec<Event>
+}
+
+impl EventBus {
+    pub fn new() -> Self {
+        EventBus {
+            pending: Vec::new()
+        }
+    }
+
+    pub fn next(&mut self) -> Event {
+        if self.pending.len() == 0 {
+            Event::new_tick()
+        } else {
+            self.pending.pop().unwrap()
+        }
+    }
+
+    pub fn push(&mut self, event: Event) {
+        self.pending.push(event);
+    }
+}