Add basic timing library

crates/lb/Cargo.toml

@@ -10,6 +10,7 @@ repository.workspace = true
 [features]
 runtime = ["tokio/rt"]
 task = ["tokio/rt", "tokio/time"]
+time = []
 fs = ["tokio/fs", "dep:walkdir", "dep:globset", "dep:tempfile"]
 net = ["tokio/net", "tokio/io-util"]
 

crates/lb/src/lib.rs

@@ -9,3 +9,5 @@ pub mod net;
 pub mod runtime;
 #[cfg(feature = "task")]
 pub mod task;
+#[cfg(feature = "time")]
+pub mod time;

crates/lb/src/time.rs

@@ -0,0 +1,30 @@
+use luaffi::{cdef, metatype};
+
+#[cdef(module = "lb:time")]
+pub struct lb_timelib;
+
+#[metatype]
+impl lb_timelib {
+    #[new]
+    extern "Lua-C" fn new() -> Self {
+        Self
+    }
+
+    pub extern "Lua-C" fn instant() -> lb_instant {
+        lb_instant::new(std::time::Instant::now())
+    }
+}
+
+#[cdef]
+pub struct lb_instant(#[opaque] std::time::Instant);
+
+#[metatype]
+impl lb_instant {
+    fn new(instant: std::time::Instant) -> Self {
+        Self(instant)
+    }
+
+    pub extern "Lua-C" fn elapsed(&self) -> f64 {
+        self.0.elapsed().as_secs_f64()
+    }
+}