Add Date::new() and Date::value_of() (#452)

Author: bnoordhuis

src/binding.cc

@@ -852,6 +852,23 @@ const v8::Array* v8__Array__New_with_elements(v8::Isolate* isolate,
 
 uint32_t v8__Array__Length(const v8::Array& self) { return self.Length(); }
 
+const v8::Date* v8__Date__New(const v8::Context& context, double time) {
+  // v8::Date::New() is kind of weird in that it returns a v8::Value,
+  // not a v8::Date, even though the object is always a Date object.
+  // Let's paper over that quirk here.
+  v8::MaybeLocal<v8::Date> maybe_date;
+
+  v8::Local<v8::Value> value;
+  if (v8::Date::New(ptr_to_local(&context), time).ToLocal(&value)) {
+    assert(value->IsDate());
+    maybe_date = value.As<v8::Date>();
+  }
+
+  return maybe_local_to_ptr(maybe_date);
+}
+
+double v8__Date__ValueOf(const v8::Date& self) { return self.ValueOf(); }
+
 const v8::External* v8__External__New(v8::Isolate* isolate, void* value) {
   return local_to_ptr(v8::External::New(isolate, value));
 }

src/date.rs

@@ -0,0 +1,29 @@
+// Copyright 2019-2020 the Deno authors. All rights reserved. MIT license.
+
+use crate::Context;
+use crate::Date;
+use crate::HandleScope;
+use crate::Local;
+
+extern "C" {
+  fn v8__Date__New(context: *const Context, value: f64) -> *const Date;
+  fn v8__Date__ValueOf(this: *const Date) -> f64;
+}
+
+/// An instance of the built-in Date constructor (ECMA-262, 15.9).
+impl Date {
+  pub fn new<'s>(
+    scope: &mut HandleScope<'s>,
+    value: f64,
+  ) -> Option<Local<'s, Date>> {
+    unsafe {
+      scope.cast_local(|sd| v8__Date__New(sd.get_current_context(), value))
+    }
+  }
+
+  /// A specialization of Value::NumberValue that is more efficient
+  /// because we know the structure of this object.
+  pub fn value_of(&self) -> f64 {
+    unsafe { v8__Date__ValueOf(self) }
+  }
+}

src/lib.rs

@@ -37,6 +37,7 @@ mod array_buffer;
 mod array_buffer_view;
 mod context;
 mod data;
+mod date;
 mod exception;
 mod external;
 mod external_references;

tests/test_api.rs

@@ -3485,3 +3485,33 @@ fn synthetic_module() {
   check("a", 1.0);
   check("b", 2.0);
 }
+
+#[allow(clippy::float_cmp)]
+#[test]
+fn date() {
+  let time = 1_291_404_900_000.; // 2010-12-03 20:35:00 - Mees <3
+
+  let _setup_guard = setup();
+  let isolate = &mut v8::Isolate::new(Default::default());
+
+  let scope = &mut v8::HandleScope::new(isolate);
+
+  let context = v8::Context::new(scope);
+  let scope = &mut v8::ContextScope::new(scope, context);
+
+  let date = v8::Date::new(scope, time).unwrap();
+  assert_eq!(date.value_of(), time);
+
+  let key = v8::String::new(scope, "d").unwrap();
+  context.global(scope).set(scope, key.into(), date.into());
+
+  let result = eval(scope, "d.toISOString()").unwrap();
+  let result = result.to_string(scope).unwrap();
+  let result = result.to_rust_string_lossy(scope);
+  assert_eq!(result, "2010-12-03T19:35:00.000Z");
+
+  // V8 chops off fractions.
+  let date = v8::Date::new(scope, std::f64::consts::PI).unwrap();
+  assert_eq!(date.value_of(), 3.0);
+  assert_eq!(date.number_value(scope).unwrap(), 3.0);
+}