[boa-dev#524] implement Math.imul()

boa/src/builtins/math/mod.rs

@@ -282,6 +282,20 @@ impl Math {
         Ok(args.iter().fold(0f64, |x, v| f64::from(v).hypot(x)).into())
     }
 
+    /// Get the result of the C-like 32-bit multiplication of the two parameters.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///  - [MDN documentation][mdn]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-math.imul
+    /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/imul
+    pub(crate) fn imul(_: &Value, args: &[Value], _: &mut Interpreter) -> ResultValue {
+        let a = args.get(0).map_or(0f64, f64::from);
+        let b = args.get(1).map_or(0f64, f64::from);
+        Ok(((a as u32).wrapping_mul(b as u32) as i32).into())
+    }
+
     /// Get the natural logarithm of a number.
     ///
     /// More information:
@@ -574,6 +588,7 @@ impl Math {
         make_builtin_fn(Self::floor, "floor", &math, 1);
         make_builtin_fn(Self::fround, "fround", &math, 1);
         make_builtin_fn(Self::hypot, "hypot", &math, 1);
+        make_builtin_fn(Self::imul, "imul", &math, 1);
         make_builtin_fn(Self::log, "log", &math, 1);
         make_builtin_fn(Self::log1p, "log1p", &math, 1);
         make_builtin_fn(Self::log10, "log10", &math, 1);

boa/src/builtins/math/tests.rs

@@ -390,6 +390,30 @@ fn hypot() {
     assert_eq!(f, String::from("Infinity"));
 }
 
+#[test]
+fn imul() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let init = r#"
+        var a = Math.imul(3, 4);
+        var b = Math.imul(-5, 12);
+        var c = Math.imul(0xffffffff, 5);
+        var d = Math.imul(0xfffffffe, 5);
+        "#;
+
+    eprintln!("{}", forward(&mut engine, init));
+
+    let a = forward_val(&mut engine, "a").unwrap();
+    let b = forward_val(&mut engine, "b").unwrap();
+    let c = forward_val(&mut engine, "c").unwrap();
+    let d = forward_val(&mut engine, "d").unwrap();
+
+    assert_eq!(a.to_number(), 12f64);
+    assert_eq!(b.to_number(), -60f64);
+    assert_eq!(c.to_number(), -5f64);
+    assert_eq!(d.to_number(), -10f64);
+}
+
 #[test]
 fn log() {
     let realm = Realm::create();