Merge pull request hush-shell#37 from caioraposo/std.rand

Add std.rand/randint

Cargo.toml

@@ -28,6 +28,7 @@ serde = "1.0"
 serde_json = "1.0"
 base64 = "0.13"
 hex = "0.4"
+rand = "0.8.5"
 
 [dev-dependencies]
 assert_matches = "1.5"

src/runtime/lib/rand.rs

@@ -0,0 +1,47 @@
+use gc::{Finalize, Trace};
+
+use super::{
+	Float,
+	NativeFun,
+	Panic,
+	RustFun,
+	Value,
+	CallContext,
+};
+use rand::{Rng, thread_rng};
+
+inventory::submit! { RustFun::from(Rand) }
+inventory::submit! { RustFun::from(RandInt) }
+
+#[derive(Trace, Finalize)]
+struct Rand;
+
+#[derive(Trace, Finalize)]
+struct RandInt;
+
+impl NativeFun for Rand {
+	fn name(&self) -> &'static str { "std.rand" }
+
+	fn call(&self, context: CallContext) -> Result<Value, Panic> {
+		let mut rng = thread_rng();
+		let args = context.args();
+		if args.is_empty() {
+			Ok(Value::Float(Float(rng.gen::<f64>())))
+		} else {
+			Err(Panic::invalid_args(args.len() as u32, 0, context.pos))
+		}
+	}
+}
+
+impl NativeFun for RandInt {
+	fn name(&self) -> &'static str { "std.randint" }
+
+	fn call(&self, context: CallContext) -> Result<Value, Panic> {
+		let mut rng = thread_rng();
+		match context.args() {
+			[ Value::Int(m), Value::Int(n) ] => Ok(Value::Int(rng.gen_range(*m..=*n))),
+			[ other, _ ] => Err(Panic::type_error(other.copy(), "int", context.pos)),
+			args => Err(Panic::invalid_args(args.len() as u32, 2, context.pos))
+		}
+	}
+}