feat(ecmascript): implement Date constructor and prototype methods (#586)

Author: kermanx

nova_vm/src/builtin_strings

@@ -461,7 +461,7 @@ unregister
 unscopables
 unshift
 URIError
-utc
+UTC
 value
 valueOf
 values

nova_vm/src/ecmascript/abstract_operations/type_conversion.rs

@@ -449,6 +449,26 @@ impl IntegerOrInfinity {
     }
 }
 
+/// ### [7.1.5 ToIntegerOrInfinity ( argument )](https://tc39.es/ecma262/#sec-tointegerorinfinity)
+pub(crate) fn to_integer_or_infinity_f64(number: f64) -> f64 {
+    // `ToIntegerOrInfinity ( argument )`
+    if number.is_nan() || number == 0.0 {
+        // 2. If number is NaN, +0𝔽, or -0𝔽, return 0.
+        0.0
+    } else if number == f64::INFINITY {
+        // 3. If number is +∞𝔽, return +∞.
+        f64::INFINITY
+    } else if number == f64::NEG_INFINITY {
+        // 4. If number is -∞𝔽, return -∞.
+        f64::NEG_INFINITY
+    } else {
+        // 5. Let integer be floor(abs(ℝ(number))).
+        // 6. If number < +0𝔽, set integer to -integer.
+        // 7. Return integer.
+        number.trunc()
+    }
+}
+
 /// ### [7.1.5 ToIntegerOrInfinity ( argument )](https://tc39.es/ecma262/#sec-tointegerorinfinity)
 pub(crate) fn to_integer_or_infinity(
     agent: &mut Agent,

nova_vm/src/ecmascript/builtins/date.rs

@@ -6,6 +6,8 @@ pub(crate) mod data;
 
 use core::ops::{Index, IndexMut};
 
+use data::DateValue;
+
 use crate::{
     ecmascript::{
         execution::{Agent, ProtoIntrinsics},
@@ -38,6 +40,18 @@ impl Date<'_> {
         Scoped::new(agent, self.unbind(), gc)
     }
 
+    /// ### get [[DateValue]]
+    #[inline]
+    pub(crate) fn date_value(self, agent: &Agent) -> DateValue {
+        agent[self].date
+    }
+
+    /// ### set [[DateValue]]
+    #[inline]
+    pub(crate) fn set_date_value(self, agent: &mut Agent, date: DateValue) {
+        agent[self].date = date;
+    }
+
     pub(crate) const fn _def() -> Self {
         Self(DateIndex::from_u32_index(0))
     }

nova_vm/src/ecmascript/builtins/date/data.rs

@@ -2,23 +2,97 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
+use std::time::SystemTime;
+
 use crate::{
-    ecmascript::types::OrdinaryObject,
+    SmallInteger,
+    ecmascript::types::{IntoValue, OrdinaryObject, Value},
     heap::{CompactionLists, HeapMarkAndSweep, WorkQueues},
 };
-use std::time::SystemTime;
+
+/// ### [21.4.1.1 Time Values and Time Range](https://tc39.es/ecma262/#sec-time-values-and-time-range)
+///
+/// A Number can exactly represent all integers from -9,007,199,254,740,992
+/// to 9,007,199,254,740,992 (21.1.2.8 and 21.1.2.6). A time value supports
+/// a slightly smaller range of -8,640,000,000,000,000 to 8,640,000,000,000,000 milliseconds.
+/// This yields a supported time value range of exactly -100,000,000 days
+/// to 100,000,000 days relative to midnight at the beginning of 1 January 1970 UTC.
+///
+/// In that case, the time value can be either:
+///
+/// - Invalid, which is presented as `i64::MAX`
+/// - An integer in the range of -8,640,000,000,000,000 to 8,640,000,000,000,000,
+///   which is represented as a non-max `i64`, and can also fit in `SmallInteger`
+#[derive(Debug, Clone, Copy)]
+#[repr(transparent)]
+pub(crate) struct DateValue(i64);
+
+impl DateValue {
+    pub const NAN: Self = Self(i64::MAX);
+
+    pub fn get_i64(self) -> Option<i64> {
+        if self.0 == i64::MAX {
+            None
+        } else {
+            Some(self.0)
+        }
+    }
+
+    pub fn get_f64(self) -> Option<f64> {
+        self.get_i64().map(|v| v as f64)
+    }
+
+    pub fn now() -> Self {
+        let now = SystemTime::now();
+        let now = now
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .expect("Time went backwards")
+            .as_millis();
+        Self(now as i64)
+    }
+}
+
+/// ### [21.4.1.31 TimeClip ( time )](https://tc39.es/ecma262/#sec-timeclip)
+///
+/// The abstract operation TimeClip takes argument time (a Number) and returns
+/// a Number. It calculates a number of milliseconds.
+pub(crate) fn time_clip(time: f64) -> DateValue {
+    // 1. If time is not finite, return NaN.
+    if !time.is_finite() {
+        return DateValue::NAN;
+    }
+
+    // 2. If abs(ℝ(time)) > 8.64 × 10**15, return NaN.
+    if time.abs() > 8.64e15 {
+        return DateValue::NAN;
+    }
+
+    // 3. Return 𝔽(! ToIntegerOrInfinity(time)).
+    DateValue(time.trunc() as i64)
+}
+
+impl<'a> IntoValue<'a> for DateValue {
+    fn into_value(self) -> Value<'a> {
+        if let Some(value) = self.get_f64() {
+            // SAFETY: `value` is guaranteed to be in the range of `SmallInteger`.
+            Value::Integer(SmallInteger::try_from(value).unwrap())
+        } else {
+            Value::nan()
+        }
+    }
+}
 
 #[derive(Debug, Clone, Copy)]
 pub struct DateHeapData {
     pub(crate) object_index: Option<OrdinaryObject<'static>>,
-    pub(crate) date: Option<SystemTime>,
+    pub(crate) date: DateValue,
 }
 
 impl DateHeapData {
     pub(crate) fn new_invalid() -> Self {
         Self {
             object_index: None,
-            date: None,
+            date: DateValue::NAN,
         }
     }
 }