Temporal `Instant` migration cont. and related changes (#3601)

* Migrate more of Instant

* Migrate round and some other adjustments

* Complete initial work on Instant

* Add some docs

* nanos -> quotient in roundNumberToIncrementAsIfPositive

* Update comments on todos

core/engine/src/bigint.rs

@@ -228,17 +228,6 @@ impl JsBigInt {
         Self::new(x.inner.as_ref().clone().add(y.inner.as_ref()))
     }
 
-    /// Utility function for performing `+` operation on more than two values.
-    #[inline]
-    #[cfg(feature = "temporal")]
-    pub(crate) fn add_n(values: &[Self]) -> Self {
-        let mut result = Self::zero();
-        for big_int in values {
-            result = Self::add(&result, big_int);
-        }
-        result
-    }
-
     /// Performs the `-` operation.
     #[inline]
     #[must_use]

core/engine/src/builtins/options.rs

@@ -110,6 +110,20 @@ impl OptionType for JsString {
     }
 }
 
+impl OptionType for f64 {
+    fn from_value(value: JsValue, context: &mut Context) -> JsResult<Self> {
+        let value = value.to_number(context)?;
+
+        if !value.is_finite() {
+            return Err(JsNativeError::range()
+                .with_message("roundingIncrement must be finite.")
+                .into());
+        }
+
+        Ok(value)
+    }
+}
+
 #[derive(Debug, Copy, Clone, Default)]
 pub(crate) enum RoundingMode {
     Ceil,
@@ -171,6 +185,7 @@ impl fmt::Display for RoundingMode {
     }
 }
 
+// TODO: remove once confirmed.
 #[cfg(feature = "temporal")]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum UnsignedRoundingMode {
@@ -182,7 +197,9 @@ pub(crate) enum UnsignedRoundingMode {
 }
 
 impl RoundingMode {
+    // TODO: remove once confirmed.
     #[cfg(feature = "temporal")]
+    #[allow(dead_code)]
     pub(crate) const fn negate(self) -> Self {
         use RoundingMode::{
             Ceil, Expand, Floor, HalfCeil, HalfEven, HalfExpand, HalfFloor, HalfTrunc, Trunc,
@@ -201,7 +218,9 @@ impl RoundingMode {
         }
     }
 
+    // TODO: remove once confirmed.
     #[cfg(feature = "temporal")]
+    #[allow(dead_code)]
     pub(crate) const fn get_unsigned_round_mode(self, is_negative: bool) -> UnsignedRoundingMode {
         use RoundingMode::{
             Ceil, Expand, Floor, HalfCeil, HalfEven, HalfExpand, HalfFloor, HalfTrunc, Trunc,

core/engine/src/builtins/temporal/instant/mod.rs

@@ -1,11 +1,11 @@
 //! Boa's implementation of ECMAScript's `Temporal.Instant` builtin object.
-#![allow(dead_code)]
 
 use crate::{
     builtins::{
-        options::{get_option, get_options_object, RoundingMode},
+        options::{get_option, get_options_object},
-        temporal::options::{
+        temporal::{
-            get_temporal_rounding_increment, get_temporal_unit, TemporalUnitGroup,
+            duration::{create_temporal_duration, to_temporal_duration_record},
+            options::{get_temporal_unit, TemporalUnitGroup},
         },
         BuiltInBuilder, BuiltInConstructor, BuiltInObject, IntrinsicObject,
     },
@@ -20,18 +20,17 @@ use crate::{
 };
 use boa_gc::{Finalize, Trace};
 use boa_profiler::Profiler;
-use boa_temporal::{components::Duration, options::TemporalUnit};
+use boa_temporal::{
-
+    components::Instant as InnerInstant,
-use super::{ns_max_instant, ns_min_instant, MIS_PER_DAY, MS_PER_DAY, NS_PER_DAY};
+    options::{TemporalRoundingMode, TemporalUnit},
-
+};
-const NANOSECONDS_PER_SECOND: i64 = 10_000_000_000;
-const NANOSECONDS_PER_MINUTE: i64 = 600_000_000_000;
-const NANOSECONDS_PER_HOUR: i64 = 36_000_000_000_000;
 
 /// The `Temporal.Instant` object.
 #[derive(Debug, Clone, Trace, Finalize, JsData)]
+// SAFETY: Instant does not contain any traceable values.
+#[boa_gc(unsafe_empty_trace)]
 pub struct Instant {
-    pub(crate) nanoseconds: JsBigInt,
+    pub(crate) inner: InnerInstant,
 }
 
 impl BuiltInObject for Instant {
@@ -131,13 +130,10 @@ impl BuiltInConstructor for Instant {
         let epoch_nanos = args.get_or_undefined(0).to_bigint(context)?;
 
         // 3. If ! IsValidEpochNanoseconds(epochNanoseconds) is false, throw a RangeError exception.
-        if !is_valid_epoch_nanos(&epoch_nanos) {
+        // NOTE: boa_temporal::Instant asserts that the epochNanoseconds are valid.
-            return Err(JsNativeError::range()
+        let instant = InnerInstant::new(epoch_nanos.as_inner().clone())?;
-                .with_message("Temporal.Instant must have a valid epochNanoseconds.")
-                .into());
-        };
         // 4. Return ? CreateTemporalInstant(epochNanoseconds, NewTarget).
-        create_temporal_instant(epoch_nanos, Some(new_target.clone()), context)
+        create_temporal_instant(instant, Some(new_target.clone()), context)
     }
 }
 
@@ -159,11 +155,7 @@ impl Instant {
                 JsNativeError::typ().with_message("the this object must be an instant object.")
             })?;
         // 3. Let ns be instant.[[Nanoseconds]].
-        let ns = &instant.nanoseconds;
+        Ok(instant.inner.epoch_seconds().into())
-        // 4. Let s be floor(ℝ(ns) / 10e9).
-        let s = (ns.to_f64() / 10e9).floor();
-        // 5. Return 𝔽(s).
-        Ok(s.into())
     }
 
     /// 8.3.4 get Temporal.Instant.prototype.epochMilliseconds
@@ -181,11 +173,9 @@ impl Instant {
                 JsNativeError::typ().with_message("the this object must be an instant object.")
             })?;
         // 3. Let ns be instant.[[Nanoseconds]].
-        let ns = &instant.nanoseconds;
         // 4. Let ms be floor(ℝ(ns) / 106).
-        let ms = (ns.to_f64() / 10e6).floor();
         // 5. Return 𝔽(ms).
-        Ok(ms.into())
+        Ok(instant.inner.epoch_milliseconds().into())
     }
 
     /// 8.3.5 get Temporal.Instant.prototype.epochMicroseconds
@@ -203,13 +193,10 @@ impl Instant {
                 JsNativeError::typ().with_message("the this object must be an instant object.")
             })?;
         // 3. Let ns be instant.[[Nanoseconds]].
-        let ns = &instant.nanoseconds;
         // 4. Let µs be floor(ℝ(ns) / 103).
-        let micro_s = (ns.to_f64() / 10e3).floor();
         // 5. Return ℤ(µs).
-        let big_int = JsBigInt::try_from(micro_s).map_err(|_| {
+        let big_int = JsBigInt::try_from(instant.inner.epoch_microseconds())
-            JsNativeError::typ().with_message("Could not convert microseconds to JsBigInt value")
+            .expect("valid microseconds is in range of BigInt");
-        })?;
         Ok(big_int.into())
     }
 
@@ -228,9 +215,10 @@ impl Instant {
                 JsNativeError::typ().with_message("the this object must be an instant object.")
             })?;
         // 3. Let ns be instant.[[Nanoseconds]].
-        let ns = &instant.nanoseconds;
         // 4. Return ns.
-        Ok(ns.clone().into())
+        let big_int = JsBigInt::try_from(instant.inner.epoch_nanoseconds())
+            .expect("valid nanoseconds is in range of BigInt");
+        Ok(big_int.into())
     }
 
     /// 8.3.7 `Temporal.Instant.prototype.add ( temporalDurationLike )`
@@ -249,8 +237,9 @@ impl Instant {
             })?;
 
         // 3. Return ? AddDurationToOrSubtractDurationFromInstant(add, instant, temporalDurationLike).
-        let temporal_duration_like = args.get_or_undefined(0);
+        let temporal_duration_like = to_temporal_duration_record(args.get_or_undefined(0))?;
-        add_or_subtract_duration_from_instant(true, &instant, temporal_duration_like, context)
+        let result = instant.inner.add(temporal_duration_like)?;
+        create_temporal_instant(result, None, context)
     }
 
     /// 8.3.8 `Temporal.Instant.prototype.subtract ( temporalDurationLike )`
@@ -269,8 +258,9 @@ impl Instant {
             })?;
 
         // 3. Return ? AddDurationToOrSubtractDurationFromInstant(subtract, instant, temporalDurationLike).
-        let temporal_duration_like = args.get_or_undefined(0);
+        let temporal_duration_like = to_temporal_duration_record(args.get_or_undefined(0))?;
-        add_or_subtract_duration_from_instant(false, &instant, temporal_duration_like, context)
+        let result = instant.inner.subtract(temporal_duration_like)?;
+        create_temporal_instant(result, None, context)
     }
 
     /// 8.3.9 `Temporal.Instant.prototype.until ( other [ , options ] )`
@@ -289,9 +279,18 @@ impl Instant {
             })?;
 
         // 3. Return ? DifferenceTemporalInstant(until, instant, other, options).
-        let other = args.get_or_undefined(0);
+        let other = to_temporal_instant(args.get_or_undefined(0))?;
-        let option = args.get_or_undefined(1);
+
-        diff_temporal_instant(true, &instant, other, option, context)
+        // Fetch the necessary options.
+        let options = get_options_object(args.get_or_undefined(1))?;
+        let mode = get_option::<TemporalRoundingMode>(&options, utf16!("roundingMode"), context)?;
+        let increment = get_option::<f64>(&options, utf16!("roundingIncrement"), context)?;
+        let smallest_unit = get_option::<TemporalUnit>(&options, utf16!("smallestUnit"), context)?;
+        let largest_unit = get_option::<TemporalUnit>(&options, utf16!("largestUnit"), context)?;
+        let result = instant
+            .inner
+            .until(&other, mode, increment, smallest_unit, largest_unit)?;
+        create_temporal_duration(result.into(), None, context).map(Into::into)
     }
 
     /// 8.3.10 `Temporal.Instant.prototype.since ( other [ , options ] )`
@@ -310,9 +309,16 @@ impl Instant {
             })?;
 
         // 3. Return ? DifferenceTemporalInstant(since, instant, other, options).
-        let other = args.get_or_undefined(0);
+        let other = to_temporal_instant(args.get_or_undefined(0))?;
-        let option = args.get_or_undefined(1);
+        let options = get_options_object(args.get_or_undefined(1))?;
-        diff_temporal_instant(false, &instant, other, option, context)
+        let mode = get_option::<TemporalRoundingMode>(&options, utf16!("roundingMode"), context)?;
+        let increment = get_option::<f64>(&options, utf16!("roundingIncrement"), context)?;
+        let smallest_unit = get_option::<TemporalUnit>(&options, utf16!("smallestUnit"), context)?;
+        let largest_unit = get_option::<TemporalUnit>(&options, utf16!("largestUnit"), context)?;
+        let result = instant
+            .inner
+            .since(&other, mode, increment, smallest_unit, largest_unit)?;
+        create_temporal_duration(result.into(), None, context).map(Into::into)
     }
 
     /// 8.3.11 `Temporal.Instant.prototype.round ( roundTo )`
@@ -362,11 +368,12 @@ impl Instant {
         // 6. NOTE: The following steps read options and perform independent validation in
         // alphabetical order (ToTemporalRoundingIncrement reads "roundingIncrement" and ToTemporalRoundingMode reads "roundingMode").
         // 7. Let roundingIncrement be ? ToTemporalRoundingIncrement(roundTo).
-        let rounding_increment = get_temporal_rounding_increment(&round_to, context)?;
+        let rounding_increment =
+            get_option::<f64>(&round_to, utf16!("roundingIncrement"), context)?;
 
         // 8. Let roundingMode be ? ToTemporalRoundingMode(roundTo, "halfExpand").
         let rounding_mode =
-            get_option(&round_to, utf16!("roundingMode"), context)?.unwrap_or_default();
+            get_option::<TemporalRoundingMode>(&round_to, utf16!("roundingMode"), context)?;
 
         // 9. Let smallestUnit be ? GetTemporalUnit(roundTo, "smallestUnit"), time, required).
         let smallest_unit = get_temporal_unit(
@@ -378,43 +385,28 @@ impl Instant {
         )?
         .ok_or_else(|| JsNativeError::range().with_message("smallestUnit cannot be undefined."))?;
 
-        let maximum = match smallest_unit {
         // 10. If smallestUnit is "hour"), then
         // a. Let maximum be HoursPerDay.
-            TemporalUnit::Hour => 24u64,
         // 11. Else if smallestUnit is "minute"), then
         // a. Let maximum be MinutesPerHour × HoursPerDay.
-            TemporalUnit::Minute => 14400u64,
         // 12. Else if smallestUnit is "second"), then
         // a. Let maximum be SecondsPerMinute × MinutesPerHour × HoursPerDay.
-            TemporalUnit::Second => 86400u64,
         // 13. Else if smallestUnit is "millisecond"), then
         // a. Let maximum be ℝ(msPerDay).
-            TemporalUnit::Millisecond => MS_PER_DAY as u64,
         // 14. Else if smallestUnit is "microsecond"), then
         // a. Let maximum be 10^3 × ℝ(msPerDay).
-            TemporalUnit::Microsecond => MIS_PER_DAY as u64,
         // 15. Else,
         // a. Assert: smallestUnit is "nanosecond".
         // b. Let maximum be nsPerDay.
-            TemporalUnit::Nanosecond => NS_PER_DAY as u64,
         // unreachable here functions as 15.a.
-            _ => unreachable!(),
-        };
-
         // 16. Perform ? ValidateTemporalRoundingIncrement(roundingIncrement, maximum, true).
-        super::validate_temporal_rounding_increment(rounding_increment.into(), maximum, true)?;
-
         // 17. Let roundedNs be RoundTemporalInstant(instant.[[Nanoseconds]], roundingIncrement, smallestUnit, roundingMode).
-        let rounded_ns = round_temporal_instant(
+        let result = instant
-            &instant.nanoseconds,
+            .inner
-            rounding_increment.into(),
+            .round(rounding_increment, smallest_unit, rounding_mode)?;
-            smallest_unit,
-            rounding_mode,
-        )?;
 
         // 18. Return ! CreateTemporalInstant(roundedNs).
-        create_temporal_instant(rounded_ns, None, context)
+        create_temporal_instant(result, None, context)
     }
 
     /// 8.3.12 `Temporal.Instant.prototype.equals ( other )`
@@ -434,7 +426,7 @@ impl Instant {
         let other = args.get_or_undefined(0);
         let other_instant = to_temporal_instant(other)?;
 
-        if instant.nanoseconds != other_instant.nanoseconds {
+        if instant.inner != other_instant {
             return Ok(false.into());
         }
         Ok(true.into())
@@ -467,30 +459,17 @@ impl Instant {
 
 // -- Instant Abstract Operations --
 
-/// 8.5.1 `IsValidEpochNanoseconds ( epochNanoseconds )`
+// 8.5.1 `IsValidEpochNanoseconds ( epochNanoseconds )`
-#[inline]
+// Implemented in `boa_temporal`
-fn is_valid_epoch_nanos(epoch_nanos: &JsBigInt) -> bool {
-    // 1. Assert: Type(epochNanoseconds) is BigInt.
-    // 2. If ℝ(epochNanoseconds) < nsMinInstant or ℝ(epochNanoseconds) > nsMaxInstant, then
-    if epoch_nanos.to_f64() < ns_min_instant().to_f64()
-        || epoch_nanos.to_f64() > ns_max_instant().to_f64()
-    {
-        // a. Return false.
-        return false;
-    }
-    // 3. Return true.
-    true
-}
 
 /// 8.5.2 `CreateTemporalInstant ( epochNanoseconds [ , newTarget ] )`
 #[inline]
 fn create_temporal_instant(
-    epoch_nanos: JsBigInt,
+    instant: InnerInstant,
     new_target: Option<JsValue>,
     context: &mut Context,
 ) -> JsResult<JsValue> {
     // 1. Assert: ! IsValidEpochNanoseconds(epochNanoseconds) is true.
-    assert!(is_valid_epoch_nanos(&epoch_nanos));
     // 2. If newTarget is not present, set newTarget to %Temporal.Instant%.
     let new_target = new_target.unwrap_or_else(|| {
         context
@@ -506,12 +485,7 @@ fn create_temporal_instant(
         get_prototype_from_constructor(&new_target, StandardConstructors::instant, context)?;
 
     // 4. Set object.[[Nanoseconds]] to epochNanoseconds.
-    let obj = JsObject::from_proto_and_data(
+    let obj = JsObject::from_proto_and_data(proto, Instant { inner: instant });
-        proto,
-        Instant {
-            nanoseconds: epoch_nanos,
-        },
-    );
 
     // 5. Return object.
     Ok(obj.into())
@@ -519,231 +493,9 @@ fn create_temporal_instant(
 
 /// 8.5.3 `ToTemporalInstant ( item )`
 #[inline]
-fn to_temporal_instant(_: &JsValue) -> JsResult<Instant> {
+fn to_temporal_instant(_: &JsValue) -> JsResult<InnerInstant> {
     // TODO: Need to implement parsing.
     Err(JsNativeError::error()
         .with_message("Instant parsing is not yet implemented.")
         .into())
 }
-
-/// 8.5.6 `AddInstant ( epochNanoseconds, hours, minutes, seconds, milliseconds, microseconds, nanoseconds )`
-#[inline]
-fn add_instant(
-    epoch_nanos: &JsBigInt,
-    hours: i32,
-    minutes: i32,
-    seconds: i32,
-    millis: i32,
-    micros: i32,
-    nanos: i32,
-) -> JsResult<JsBigInt> {
-    let result = JsBigInt::add_n(&[
-        JsBigInt::mul(
-            &JsBigInt::from(hours),
-            &JsBigInt::from(NANOSECONDS_PER_HOUR),
-        ),
-        JsBigInt::mul(
-            &JsBigInt::from(minutes),
-            &JsBigInt::from(NANOSECONDS_PER_MINUTE),
-        ),
-        JsBigInt::mul(
-            &JsBigInt::from(seconds),
-            &JsBigInt::from(NANOSECONDS_PER_SECOND),
-        ),
-        JsBigInt::mul(&JsBigInt::from(millis), &JsBigInt::from(10_000_000_i32)),
-        JsBigInt::mul(&JsBigInt::from(micros), &JsBigInt::from(1000_i32)),
-        JsBigInt::add(&JsBigInt::from(nanos), epoch_nanos),
-    ]);
-    if !is_valid_epoch_nanos(&result) {
-        return Err(JsNativeError::range()
-            .with_message("result is not a valid epoch nanosecond value.")
-            .into());
-    }
-    Ok(result)
-}
-
-/// 8.5.7 `DifferenceInstant ( ns1, ns2, roundingIncrement, smallestUnit, largestUnit, roundingMode )`
-#[inline]
-fn diff_instant(
-    ns1: &JsBigInt,
-    ns2: &JsBigInt,
-    _rounding_increment: f64,
-    _smallest_unit: TemporalUnit,
-    _largest_unit: TemporalUnit,
-    _rounding_mode: RoundingMode,
-    _context: &mut Context,
-) -> JsResult<Duration> {
-    // 1. Let difference be ℝ(ns2) - ℝ(ns1).
-    let difference = JsBigInt::sub(ns1, ns2);
-    // 2. Let nanoseconds be remainder(difference, 1000).
-    let _nanoseconds = JsBigInt::rem(&difference, &JsBigInt::from(1000));
-    // 3. Let microseconds be remainder(truncate(difference / 1000), 1000).
-    let truncated_micro = JsBigInt::try_from((&difference.to_f64() / 1000_f64).trunc())
-        .map_err(|e| JsNativeError::typ().with_message(e.to_string()))?;
-    let _microseconds = JsBigInt::rem(&truncated_micro, &JsBigInt::from(1000));
-
-    // 4. Let milliseconds be remainder(truncate(difference / 106), 1000).
-    let truncated_milli = JsBigInt::try_from((&difference.to_f64() / 1_000_000_f64).trunc())
-        .map_err(|e| JsNativeError::typ().with_message(e.to_string()))?;
-    let _milliseconds = JsBigInt::rem(&truncated_milli, &JsBigInt::from(1000));
-
-    // 5. Let seconds be truncate(difference / 10^9).
-    let _seconds = (&difference.to_f64() / 1_000_000_000_f64).trunc();
-
-    // TODO: Update to new Temporal library
-    // 6. If smallestUnit is "nanosecond" and roundingIncrement is 1, then
-    // a. Return ! BalanceTimeDuration(0, 0, 0, seconds, milliseconds, microseconds, nanoseconds, largestUnit).
-    // 7. Let roundResult be ! RoundDuration(0, 0, 0, 0, 0, 0, seconds, milliseconds, microseconds, nanoseconds, roundingIncrement, smallestUnit, largestUnit, roundingMode).
-    // 8. Assert: roundResult.[[Days]] is 0.
-    // 9. Return ! BalanceTimeDuration(0, roundResult.[[Hours]], roundResult.[[Minutes]],
-    //    roundResult.[[Seconds]], roundResult.[[Milliseconds]], roundResult.[[Microseconds]],
-    //    roundResult.[[Nanoseconds]], largestUnit).
-
-    Err(JsNativeError::error()
-        .with_message("not yet implemented.")
-        .into())
-}
-
-/// 8.5.8 `RoundTemporalInstant ( ns, increment, unit, roundingMode )`
-#[inline]
-fn round_temporal_instant(
-    ns: &JsBigInt,
-    increment: f64,
-    unit: TemporalUnit,
-    rounding_mode: RoundingMode,
-) -> JsResult<JsBigInt> {
-    let increment_ns = match unit {
-        // 1. If unit is "hour"), then
-        TemporalUnit::Hour => {
-            // a. Let incrementNs be increment × 3.6 × 10^12.
-            increment as i64 * NANOSECONDS_PER_HOUR
-        }
-        // 2. Else if unit is "minute"), then
-        TemporalUnit::Minute => {
-            // a. Let incrementNs be increment × 6 × 10^10.
-            increment as i64 * NANOSECONDS_PER_MINUTE
-        }
-        // 3. Else if unit is "second"), then
-        TemporalUnit::Second => {
-            // a. Let incrementNs be increment × 10^9.
-            increment as i64 * NANOSECONDS_PER_SECOND
-        }
-        // 4. Else if unit is "millisecond"), then
-        TemporalUnit::Millisecond => {
-            // a. Let incrementNs be increment × 10^6.
-            increment as i64 * 1_000_000
-        }
-        // 5. Else if unit is "microsecond"), then
-        TemporalUnit::Microsecond => {
-            // a. Let incrementNs be increment × 10^3.
-            increment as i64 * 1000
-        }
-        // 6. Else,
-        TemporalUnit::Nanosecond => {
-            // NOTE: We shouldn't have to assert here as `unreachable` asserts instead.
-            // a. Assert: unit is "nanosecond".
-            // b. Let incrementNs be increment.
-            increment as i64
-        }
-        _ => unreachable!(),
-    };
-
-    // 7. Return ℤ(RoundNumberToIncrementAsIfPositive(ℝ(ns), incrementNs, roundingMode)).
-    super::round_to_increment_as_if_positive(ns, increment_ns, rounding_mode)
-}
-
-/// 8.5.10 `DifferenceTemporalInstant ( operation, instant, other, options )`
-#[inline]
-fn diff_temporal_instant(
-    op: bool,
-    instant: &Instant,
-    other: &JsValue,
-    options: &JsValue,
-    context: &mut Context,
-) -> JsResult<JsValue> {
-    // 1. If operation is since, let sign be -1. Otherwise, let sign be 1.
-    let _sign = if op { 1_f64 } else { -1_f64 };
-    // 2. Set other to ? ToTemporalInstant(other).
-    let other = to_temporal_instant(other)?;
-    // 3. Let resolvedOptions be ? CopyOptions(options).
-    let resolved_options =
-        super::snapshot_own_properties(&get_options_object(options)?, None, None, context)?;
-
-    // 4. Let settings be ? GetDifferenceSettings(operation, resolvedOptions, time, « », "nanosecond"), "second").
-    let settings = super::get_diff_settings(
-        op,
-        &resolved_options,
-        TemporalUnitGroup::Time,
-        &[],
-        TemporalUnit::Nanosecond,
-        TemporalUnit::Second,
-        context,
-    )?;
-
-    // 5. Let result be DifferenceInstant(instant.[[Nanoseconds]], other.[[Nanoseconds]], settings.[[RoundingIncrement]], settings.[[SmallestUnit]], settings.[[LargestUnit]], settings.[[RoundingMode]]).
-    let _result = diff_instant(
-        &instant.nanoseconds,
-        &other.nanoseconds,
-        settings.3,
-        settings.0,
-        settings.1,
-        settings.2,
-        context,
-    )?;
-
-    // TODO: diff_instant will error so this shouldn't run.
-    unimplemented!();
-    // 6. Return ! CreateTemporalDuration(0, 0, 0, 0, sign × result.[[Hours]], sign × result.[[Minutes]], sign × result.[[Seconds]], sign × result.[[Milliseconds]], sign × result.[[Microseconds]], sign × result.[[Nanoseconds]]).
-}
-
-/// 8.5.11 `AddDurationToOrSubtractDurationFromInstant ( operation, instant, temporalDurationLike )`
-#[inline]
-fn add_or_subtract_duration_from_instant(
-    op: bool,
-    instant: &Instant,
-    temporal_duration_like: &JsValue,
-    context: &mut Context,
-) -> JsResult<JsValue> {
-    // 1. If operation is subtract, let sign be -1. Otherwise, let sign be 1.
-    let sign = if op { 1 } else { -1 };
-    // 2. Let duration be ? ToTemporalDurationRecord(temporalDurationLike).
-    let duration = super::to_temporal_duration_record(temporal_duration_like)?;
-    // 3. If duration.[[Days]] is not 0, throw a RangeError exception.
-    if duration.date().days() != 0_f64 {
-        return Err(JsNativeError::range()
-            .with_message("DurationDays cannot be 0")
-            .into());
-    }
-    // 4. If duration.[[Months]] is not 0, throw a RangeError exception.
-    if duration.date().months() != 0_f64 {
-        return Err(JsNativeError::range()
-            .with_message("DurationMonths cannot be 0")
-            .into());
-    }
-    // 5. If duration.[[Weeks]] is not 0, throw a RangeError exception.
-    if duration.date().weeks() != 0_f64 {
-        return Err(JsNativeError::range()
-            .with_message("DurationWeeks cannot be 0")
-            .into());
-    }
-    // 6. If duration.[[Years]] is not 0, throw a RangeError exception.
-    if duration.date().years() != 0_f64 {
-        return Err(JsNativeError::range()
-            .with_message("DurationYears cannot be 0")
-            .into());
-    }
-    // 7. Let ns be ? AddInstant(instant.[[Nanoseconds]], sign × duration.[[Hours]],
-    // sign × duration.[[Minutes]], sign × duration.[[Seconds]], sign × duration.[[Milliseconds]],
-    // sign × duration.[[Microseconds]], sign × duration.[[Nanoseconds]]).
-    let new = add_instant(
-        &instant.nanoseconds,
-        sign * duration.time().hours() as i32,
-        sign * duration.time().minutes() as i32,
-        sign * duration.time().seconds() as i32,
-        sign * duration.time().milliseconds() as i32,
-        sign * duration.time().microseconds() as i32,
-        sign * duration.time().nanoseconds() as i32,
-    )?;
-    // 8. Return ! CreateTemporalInstant(ns).
-    create_temporal_instant(new, None, context)
-}

core/engine/src/builtins/temporal/mod.rs

@@ -22,41 +22,30 @@ mod zoned_date_time;
 #[cfg(test)]
 mod tests;
 
-use self::options::{get_temporal_rounding_increment, get_temporal_unit, TemporalUnitGroup};
 pub use self::{
     calendar::*, duration::*, instant::*, now::*, plain_date::*, plain_date_time::*,
     plain_month_day::*, plain_time::*, plain_year_month::*, time_zone::*, zoned_date_time::*,
 };
 
 use crate::{
-    builtins::{
+    builtins::{iterable::IteratorRecord, BuiltInBuilder, BuiltInObject, IntrinsicObject},
-        iterable::IteratorRecord,
-        options::{get_option, RoundingMode, UnsignedRoundingMode},
-        BuiltInBuilder, BuiltInObject, IntrinsicObject,
-    },
     context::intrinsics::Intrinsics,
     js_string,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     value::Type,
     Context, JsBigInt, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_profiler::Profiler;
-use boa_temporal::options::TemporalUnit;
+use boa_temporal::NS_PER_DAY;
-
-// Relavant numeric constants
-/// Nanoseconds per day constant: 8.64e+13
-pub(crate) const NS_PER_DAY: i64 = 86_400_000_000_000;
-/// Microseconds per day constant: 8.64e+10
-pub(crate) const MIS_PER_DAY: i64 = 8_640_000_000;
-/// Milliseconds per day constant: 8.64e+7
-pub(crate) const MS_PER_DAY: i32 = 24 * 60 * 60 * 1000;
 
+// TODO: Remove in favor of `boa_temporal`
 pub(crate) fn ns_max_instant() -> JsBigInt {
     JsBigInt::from(i128::from(NS_PER_DAY) * 100_000_000_i128)
 }
 
+// TODO: Remove in favor of `boa_temporal`
 pub(crate) fn ns_min_instant() -> JsBigInt {
     JsBigInt::from(i128::from(NS_PER_DAY) * -100_000_000_i128)
 }
@@ -226,9 +215,7 @@ pub(crate) fn _iterator_to_list_of_types(
 // Note: implemented on IsoDateRecord.
 
 // Abstract Operation 13.3 `EpochDaysToEpochMs`
-pub(crate) fn _epoch_days_to_epoch_ms(day: i32, time: i32) -> f64 {
+// Migrated to `boa_temporal`
-    f64::from(day).mul_add(f64::from(MS_PER_DAY), f64::from(time))
-}
 
 // 13.4 Date Equations
 // implemented in temporal/date_equations.rs
@@ -306,127 +293,14 @@ pub(crate) fn to_relative_temporal_object(
 // 13.26 `GetUnsignedRoundingMode ( roundingMode, isNegative )`
 // Implemented on RoundingMode in builtins/options.rs
 
-/// 13.27 `ApplyUnsignedRoundingMode ( x, r1, r2, unsignedRoundingMode )`
+// 13.27 `ApplyUnsignedRoundingMode ( x, r1, r2, unsignedRoundingMode )`
-#[inline]
+// Migrated to `boa_temporal`
-fn apply_unsigned_rounding_mode(
-    x: f64,
-    r1: f64,
-    r2: f64,
-    unsigned_rounding_mode: UnsignedRoundingMode,
-) -> f64 {
-    // 1. If x is equal to r1, return r1.
-    if (x - r1).abs() == 0.0 {
-        return r1;
-    };
-    // 2. Assert: r1 < x < r2.
-    assert!(r1 < x && x < r2);
-    // 3. Assert: unsignedRoundingMode is not undefined.
-
-    // 4. If unsignedRoundingMode is zero, return r1.
-    if unsigned_rounding_mode == UnsignedRoundingMode::Zero {
-        return r1;
-    };
-    // 5. If unsignedRoundingMode is infinity, return r2.
-    if unsigned_rounding_mode == UnsignedRoundingMode::Infinity {
-        return r2;
-    };
-
-    // 6. Let d1 be x – r1.
-    let d1 = x - r1;
-    // 7. Let d2 be r2 – x.
-    let d2 = r2 - x;
-    // 8. If d1 < d2, return r1.
-    if d1 < d2 {
-        return r1;
-    }
-    // 9. If d2 < d1, return r2.
-    if d2 < d1 {
-        return r2;
-    }
-    // 10. Assert: d1 is equal to d2.
-    assert!((d1 - d2).abs() == 0.0);
 
-    // 11. If unsignedRoundingMode is half-zero, return r1.
+// 13.28 `RoundNumberToIncrement ( x, increment, roundingMode )`
-    if unsigned_rounding_mode == UnsignedRoundingMode::HalfZero {
+// Migrated to `boa_temporal`
-        return r1;
-    };
-    // 12. If unsignedRoundingMode is half-infinity, return r2.
-    if unsigned_rounding_mode == UnsignedRoundingMode::HalfInfinity {
-        return r2;
-    };
-    // 13. Assert: unsignedRoundingMode is half-even.
-    assert!(unsigned_rounding_mode == UnsignedRoundingMode::HalfEven);
-    // 14. Let cardinality be (r1 / (r2 – r1)) modulo 2.
-    let cardinality = (r1 / (r2 - r1)) % 2.0;
-    // 15. If cardinality is 0, return r1.
-    if cardinality == 0.0 {
-        return r1;
-    }
-    // 16. Return r2.
-    r2
-}
 
-/// 13.28 `RoundNumberToIncrement ( x, increment, roundingMode )`
+// 13.29 `RoundNumberToIncrementAsIfPositive ( x, increment, roundingMode )`
-pub(crate) fn _round_number_to_increment(
+// Migrated to `boa_temporal`
-    x: f64,
-    increment: f64,
-    rounding_mode: RoundingMode,
-) -> f64 {
-    // 1. Let quotient be x / increment.
-    let mut quotient = x / increment;
-
-    // 2. If quotient < 0, then
-    let is_negative = if quotient < 0_f64 {
-        // a. Let isNegative be true.
-        // b. Set quotient to -quotient.
-        quotient = -quotient;
-        true
-    // 3. Else,
-    } else {
-        // a. Let isNegative be false.
-        false
-    };
-
-    // 4. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, isNegative).
-    let unsigned_rounding_mode = rounding_mode.get_unsigned_round_mode(is_negative);
-    // 5. Let r1 be the largest integer such that r1 ≤ quotient.
-    let r1 = quotient.ceil();
-    // 6. Let r2 be the smallest integer such that r2 > quotient.
-    let r2 = quotient.floor();
-    // 7. Let rounded be ApplyUnsignedRoundingMode(quotient, r1, r2, unsignedRoundingMode).
-    let mut rounded = apply_unsigned_rounding_mode(quotient, r1, r2, unsigned_rounding_mode);
-    // 8. If isNegative is true, set rounded to -rounded.
-    if is_negative {
-        rounded = -rounded;
-    };
-    // 9. Return rounded × increment.
-    rounded * increment
-}
-
-/// 13.29 `RoundNumberToIncrementAsIfPositive ( x, increment, roundingMode )`
-#[inline]
-pub(crate) fn round_to_increment_as_if_positive(
-    ns: &JsBigInt,
-    increment: i64,
-    rounding_mode: RoundingMode,
-) -> JsResult<JsBigInt> {
-    // 1. Let quotient be x / increment.
-    let q = ns.to_f64() / increment as f64;
-    // 2. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, false).
-    let unsigned_rounding_mode = rounding_mode.get_unsigned_round_mode(false);
-    // 3. Let r1 be the largest integer such that r1 ≤ quotient.
-    let r1 = q.trunc();
-    // 4. Let r2 be the smallest integer such that r2 > quotient.
-    let r2 = q.trunc() + 1.0;
-    // 5. Let rounded be ApplyUnsignedRoundingMode(quotient, r1, r2, unsignedRoundingMode).
-    let rounded = apply_unsigned_rounding_mode(q, r1, r2, unsigned_rounding_mode);
-
-    // 6. Return rounded × increment.
-    let rounded = JsBigInt::try_from(rounded)
-        .map_err(|err| JsNativeError::typ().with_message(err.to_string()))?;
-
-    Ok(JsBigInt::mul(&rounded, &JsBigInt::from(increment)))
-}
 
 /// 13.43 `ToPositiveIntegerWithTruncation ( argument )`
 #[inline]
@@ -480,174 +354,13 @@ pub(crate) fn to_integer_if_integral(arg: &JsValue, context: &mut Context) -> Js
 // See fields.rs
 
 // NOTE: op -> true == until | false == since
-/// 13.47 `GetDifferenceSettings ( operation, options, unitGroup, disallowedUnits, fallbackSmallestUnit, smallestLargestDefaultUnit )`
+// 13.47 `GetDifferenceSettings ( operation, options, unitGroup, disallowedUnits, fallbackSmallestUnit, smallestLargestDefaultUnit )`
-#[inline]
+// Migrated to `boa_temporal`
-pub(crate) fn get_diff_settings(
-    op: bool,
-    options: &JsObject,
-    unit_group: TemporalUnitGroup,
-    disallowed_units: &[TemporalUnit],
-    fallback_smallest_unit: TemporalUnit,
-    smallest_largest_default_unit: TemporalUnit,
-    context: &mut Context,
-) -> JsResult<(TemporalUnit, TemporalUnit, RoundingMode, f64)> {
-    // 1. NOTE: The following steps read options and perform independent validation in alphabetical order (ToTemporalRoundingIncrement reads "roundingIncrement" and ToTemporalRoundingMode reads "roundingMode").
-    // 2. Let largestUnit be ? GetTemporalUnit(options, "largestUnit", unitGroup, "auto").
-    let mut largest_unit =
-        get_temporal_unit(options, utf16!("largestUnit"), unit_group, None, context)?
-            .unwrap_or(TemporalUnit::Auto);
-
-    // 3. If disallowedUnits contains largestUnit, throw a RangeError exception.
-    if disallowed_units.contains(&largest_unit) {
-        return Err(JsNativeError::range()
-            .with_message("largestUnit is not an allowed unit.")
-            .into());
-    }
-
-    // 4. Let roundingIncrement be ? ToTemporalRoundingIncrement(options).
-    let rounding_increment = get_temporal_rounding_increment(options, context)?;
-
-    // 5. Let roundingMode be ? ToTemporalRoundingMode(options, "trunc").
-    let mut rounding_mode =
-        get_option(options, utf16!("roundingMode"), context)?.unwrap_or(RoundingMode::Trunc);
-
-    // 6. If operation is since, then
-    if !op {
-        // a. Set roundingMode to ! NegateTemporalRoundingMode(roundingMode).
-        rounding_mode = rounding_mode.negate();
-    }
-
-    // 7. Let smallestUnit be ? GetTemporalUnit(options, "smallestUnit", unitGroup, fallbackSmallestUnit).
-    let smallest_unit =
-        get_temporal_unit(options, utf16!("smallestUnit"), unit_group, None, context)?
-            .unwrap_or(fallback_smallest_unit);
-
-    // 8. If disallowedUnits contains smallestUnit, throw a RangeError exception.
-    if disallowed_units.contains(&smallest_unit) {
-        return Err(JsNativeError::range()
-            .with_message("smallestUnit is not an allowed unit.")
-            .into());
-    }
-
-    // 9. Let defaultLargestUnit be ! LargerOfTwoTemporalUnits(smallestLargestDefaultUnit, smallestUnit).
-    let default_largest_unit = core::cmp::max(smallest_largest_default_unit, smallest_unit);
-
-    // 10. If largestUnit is "auto", set largestUnit to defaultLargestUnit.
-    if largest_unit == TemporalUnit::Auto {
-        largest_unit = default_largest_unit;
-    }
-
-    // 11. If LargerOfTwoTemporalUnits(largestUnit, smallestUnit) is not largestUnit, throw a RangeError exception.
-    if largest_unit != core::cmp::max(largest_unit, smallest_unit) {
-        return Err(JsNativeError::range()
-            .with_message("largestUnit must be larger than smallestUnit")
-            .into());
-    }
-
-    // 12. Let maximum be ! MaximumTemporalDurationRoundingIncrement(smallestUnit).
-    let maximum = smallest_unit.to_maximum_rounding_increment();
-
-    // 13. If maximum is not undefined, perform ? ValidateTemporalRoundingIncrement(roundingIncrement, maximum, false).
-    if let Some(max) = maximum {
-        validate_temporal_rounding_increment(rounding_increment.into(), max.into(), false)?;
-    }
-
-    // 14. Return the Record { [[SmallestUnit]]: smallestUnit, [[LargestUnit]]: largestUnit, [[RoundingMode]]: roundingMode, [[RoundingIncrement]]: roundingIncrement, }.
-    Ok((
-        smallest_unit,
-        largest_unit,
-        rounding_mode,
-        rounding_increment.into(),
-    ))
-}
 
 // NOTE: used for MergeFields methods. Potentially can be omitted in favor of `TemporalFields`.
-/// 14.6 `CopyDataProperties ( target, source, excludedKeys [ , excludedValues ] )`
+// 14.6 `CopyDataProperties ( target, source, excludedKeys [ , excludedValues ] )`
-pub(crate) fn copy_data_properties(
+// Migrated or repurposed to `boa_temporal`/`fields.rs`
-    target: &JsObject,
-    source: &JsValue,
-    excluded_keys: &Vec<JsString>,
-    excluded_values: Option<&Vec<JsValue>>,
-    context: &mut Context,
-) -> JsResult<()> {
-    // 1. If source is undefined or null, return unused.
-    if source.is_null_or_undefined() {
-        return Ok(());
-    }
-
-    // 2. Let from be ! ToObject(source).
-    let from = source.to_object(context)?;
-
-    // 3. Let keys be ? from.[[OwnPropertyKeys]]().
-    let keys = from.__own_property_keys__(context)?;
-
-    // 4. For each element nextKey of keys, do
-    for next_key in keys {
-        // a. Let excluded be false.
-        let mut excluded = false;
-        // b. For each element e of excludedItemsexcludedKeys, do
-        for e in excluded_keys {
-            // i. If SameValue(e, nextKey) is true, then
-            if next_key.to_string() == e.to_std_string_escaped() {
-                // 1. Set excluded to true.
-                excluded = true;
-            }
-        }
-
-        // c. If excluded is false, then
-        if !excluded {
-            // i. Let desc be ? from.[[GetOwnProperty]](nextKey).
-            let desc = from.__get_own_property__(&next_key, &mut context.into())?;
-            // ii. If desc is not undefined and desc.[[Enumerable]] is true, then
-            match desc {
-                Some(d)
-                    if d.enumerable()
-                        .expect("enumerable field must be set per spec.") =>
-                {
-                    // 1. Let propValue be ? Get(from, nextKey).
-                    let prop_value = from.get(next_key.clone(), context)?;
-                    // 2. If excludedValues is present, then
-                    if let Some(values) = excluded_values {
-                        // a. For each element e of excludedValues, do
-                        for e in values {
-                            // i. If SameValue(e, propValue) is true, then
-                            if JsValue::same_value(e, &prop_value) {
-                                // i. Set excluded to true.
-                                excluded = true;
-                            }
-                        }
-                    }
-
-                    // 3. PerformIf excluded is false, perform ! CreateDataPropertyOrThrow(target, nextKey, propValue).
-                    if !excluded {
-                        target.create_data_property_or_throw(next_key, prop_value, context)?;
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    // 5. Return unused.
-    Ok(())
-}
 
 // Note: Deviates from Proposal spec -> proto appears to be always null across the specification.
-/// 14.7 `SnapshotOwnProperties ( source, proto [ , excludedKeys [ , excludedValues ] ] )`
+// 14.7 `SnapshotOwnProperties ( source, proto [ , excludedKeys [ , excludedValues ] ] )`
-fn snapshot_own_properties(
+// Migrated or repurposed to `boa_temporal`/`fields.rs`
-    source: &JsObject,
-    excluded_keys: Option<Vec<JsString>>,
-    excluded_values: Option<Vec<JsValue>>,
-    context: &mut Context,
-) -> JsResult<JsObject> {
-    // 1. Let copy be OrdinaryObjectCreate(proto).
-    let copy = JsObject::with_null_proto();
-    // 2. If excludedKeys is not present, set excludedKeys to « ».
-    let keys = excluded_keys.unwrap_or_default();
-    // 3. If excludedValues is not present, set excludedValues to « ».
-    let values = excluded_values.unwrap_or_default();
-    // 4. Perform ? CopyDataProperties(copy, source, excludedKeys, excludedValues).
-    copy_data_properties(&copy, &source.clone().into(), &keys, Some(&values), context)?;
-    // 5. Return copy.
-    Ok(copy)
-}

core/engine/src/builtins/temporal/options.rs

@@ -13,11 +13,13 @@ use crate::{
     js_string, Context, JsNativeError, JsObject, JsResult,
 };
 use boa_temporal::options::{
-    ArithmeticOverflow, DurationOverflow, InstantDisambiguation, OffsetDisambiguation, TemporalUnit,
+    ArithmeticOverflow, DurationOverflow, InstantDisambiguation, OffsetDisambiguation,
+    TemporalRoundingMode, TemporalUnit,
 };
 
 // TODO: Expand docs on the below options.
 
+// TODO: Remove and refactor: migrate to `boa_temporal`
 #[inline]
 pub(crate) fn get_temporal_rounding_increment(
     options: &JsObject,
@@ -131,3 +133,4 @@ impl ParsableOptionType for ArithmeticOverflow {}
 impl ParsableOptionType for DurationOverflow {}
 impl ParsableOptionType for InstantDisambiguation {}
 impl ParsableOptionType for OffsetDisambiguation {}
+impl ParsableOptionType for TemporalRoundingMode {}

core/temporal/src/components/duration.rs

@@ -61,6 +61,11 @@ impl Duration {
     pub(crate) fn one_week(week_value: f64) -> Self {
         Self::from_date_duration(DateDuration::new_unchecked(0f64, 0f64, week_value, 0f64))
     }
+
+    /// Utility that checks whether `Duration`'s `DateDuration` is empty.
+    pub(crate) fn is_time_duration(&self) -> bool {
+        self.date().iter().any(|x| x != 0f64)
+    }
 }
 
 // ==== Public Duration API ====
@@ -934,6 +939,15 @@ fn duration_sign(set: &Vec<f64>) -> i32 {
     0
 }
 
+impl From<TimeDuration> for Duration {
+    fn from(value: TimeDuration) -> Self {
+        Self {
+            time: value,
+            date: DateDuration::default(),
+        }
+    }
+}
+
 // ==== FromStr trait impl ====
 
 impl FromStr for Duration {

core/temporal/src/components/duration/time.rs

@@ -292,6 +292,20 @@ impl TimeDuration {
         }
     }
 
+    /// Returns a negated `TimeDuration`.
+    #[inline]
+    #[must_use]
+    pub fn neg(&self) -> Self {
+        Self {
+            hours: self.hours * -1f64,
+            minutes: self.minutes * -1f64,
+            seconds: self.seconds * -1f64,
+            milliseconds: self.milliseconds * -1f64,
+            microseconds: self.microseconds * -1f64,
+            nanoseconds: self.nanoseconds * -1f64,
+        }
+    }
+
     /// Balances a `TimeDuration` given a day value and the largest unit. `balance` will return
     /// the balanced `day` and `TimeDuration`.
     ///

core/temporal/src/components/instant.rs

@@ -1,13 +1,17 @@
 //! An implementation of the Temporal Instant.
 
 use crate::{
-    components::duration::TimeDuration,
+    components::{duration::TimeDuration, Duration},
-    options::{DifferenceSettings, TemporalUnit},
+    options::{TemporalRoundingMode, TemporalUnit},
-    TemporalError, TemporalResult,
+    utils, TemporalError, TemporalResult, MS_PER_DAY, NS_PER_DAY,
 };
 
 use num_bigint::BigInt;
-use num_traits::ToPrimitive;
+use num_traits::{FromPrimitive, ToPrimitive};
+
+const NANOSECONDS_PER_SECOND: f64 = 1e9;
+const NANOSECONDS_PER_MINUTE: f64 = 60f64 * NANOSECONDS_PER_SECOND;
+const NANOSECONDS_PER_HOUR: f64 = 60f64 * NANOSECONDS_PER_MINUTE;
 
 /// The native Rust implementation of `Temporal.Instant`
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
@@ -18,6 +22,23 @@ pub struct Instant {
 // ==== Private API ====
 
 impl Instant {
+    /// Adds a `TimeDuration` to the current `Instant`.
+    ///
+    /// Temporal-Proposal equivalent: `AddDurationToOrSubtractDurationFrom`.
+    pub(crate) fn add_to_instant(&self, duration: &TimeDuration) -> TemporalResult<Self> {
+        let result = self.epoch_nanoseconds()
+            + duration.nanoseconds
+            + (duration.microseconds * 1000f64)
+            + (duration.milliseconds * 1_000_000f64)
+            + (duration.seconds * NANOSECONDS_PER_SECOND)
+            + (duration.minutes * NANOSECONDS_PER_MINUTE)
+            + (duration.hours * NANOSECONDS_PER_HOUR);
+        let nanos = BigInt::from_f64(result).ok_or_else(|| {
+            TemporalError::range().with_message("Duration added to instant exceeded valid range.")
+        })?;
+        Self::new(nanos)
+    }
+
     // TODO: Add test for `diff_instant`.
     // NOTE(nekevss): As the below is internal, op will be left as a boolean
     // with a `since` op being true and `until` being false.
@@ -27,35 +48,89 @@ impl Instant {
         &self,
         op: bool,
         other: &Self,
-        settings: DifferenceSettings, // TODO: Determine DifferenceSettings fate -> is there a better way to approach this.
+        rounding_mode: Option<TemporalRoundingMode>,
+        rounding_increment: Option<f64>,
+        largest_unit: Option<TemporalUnit>,
+        smallest_unit: Option<TemporalUnit>,
     ) -> TemporalResult<TimeDuration> {
-        let diff = self
+        // diff the instant and determine its component values.
-            .nanos
+        let diff = self.to_f64() - other.to_f64();
-            .to_f64()
-            .expect("valid instant is representable by f64.")
-            - other
-                .nanos
-                .to_f64()
-                .expect("Valid instant nanos is representable by f64.");
         let nanos = diff.rem_euclid(1000f64);
         let micros = (diff / 1000f64).trunc().rem_euclid(1000f64);
         let millis = (diff / 1_000_000f64).trunc().rem_euclid(1000f64);
-        let secs = (diff / 1_000_000_000f64).trunc();
+        let secs = (diff / NANOSECONDS_PER_SECOND).trunc();
+
+        // Handle the settings provided to `diff_instant`
+        let rounding_increment = rounding_increment.unwrap_or(1.0);
+        let rounding_mode = if op {
+            rounding_mode
+                .unwrap_or(TemporalRoundingMode::Trunc)
+                .negate()
+        } else {
+            rounding_mode.unwrap_or(TemporalRoundingMode::Trunc)
+        };
+        let smallest_unit = smallest_unit.unwrap_or(TemporalUnit::Nanosecond);
+        // Use the defaultlargestunit which is max smallestlargestdefault and smallestunit
+        let largest_unit = largest_unit.unwrap_or(smallest_unit.max(TemporalUnit::Second));
+
+        // TODO: validate roundingincrement
+        // Steps 11-13 of 13.47 GetDifferenceSettings
 
-        if settings.smallest_unit == TemporalUnit::Nanosecond {
+        if smallest_unit == TemporalUnit::Nanosecond {
             let (_, result) = TimeDuration::new_unchecked(0f64, 0f64, secs, millis, micros, nanos)
-                .balance(0f64, settings.largest_unit)?;
+                .balance(0f64, largest_unit)?;
             return Ok(result);
         }
 
         let (round_result, _) = TimeDuration::new(0f64, 0f64, secs, millis, micros, nanos)?.round(
-            settings.rounding_increment,
+            rounding_increment,
-            settings.smallest_unit,
+            smallest_unit,
-            settings.rounding_mode,
+            rounding_mode,
         )?;
-        let (_, result) = round_result.balance(0f64, settings.largest_unit)?;
+        let (_, result) = round_result.balance(0f64, largest_unit)?;
         Ok(result)
     }
+
+    /// Rounds a current `Instant` given the resolved options, returning a `BigInt` result.
+    pub(crate) fn round_instant(
+        &self,
+        increment: f64,
+        unit: TemporalUnit,
+        rounding_mode: TemporalRoundingMode,
+    ) -> TemporalResult<BigInt> {
+        let increment_nanos = match unit {
+            TemporalUnit::Hour => increment * NANOSECONDS_PER_HOUR,
+            TemporalUnit::Minute => increment * NANOSECONDS_PER_MINUTE,
+            TemporalUnit::Second => increment * NANOSECONDS_PER_SECOND,
+            TemporalUnit::Millisecond => increment * 1_000_000f64,
+            TemporalUnit::Microsecond => increment * 1_000f64,
+            TemporalUnit::Nanosecond => increment,
+            _ => {
+                return Err(TemporalError::range()
+                    .with_message("Invalid unit provided for Instant::round."))
+            }
+        };
+
+        let rounded = utils::round_number_to_increment_as_if_positive(
+            self.to_f64(),
+            increment_nanos,
+            rounding_mode,
+        );
+
+        BigInt::from_f64(rounded)
+            .ok_or_else(|| TemporalError::range().with_message("Invalid rounded Instant value."))
+    }
+
+    /// Utility for converting `Instant` to f64.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if called on an invalid `Instant`.
+    pub(crate) fn to_f64(&self) -> f64 {
+        self.nanos
+            .to_f64()
+            .expect("A valid instant is representable by f64.")
+    }
 }
 
 // ==== Public API ====
@@ -71,6 +146,105 @@ impl Instant {
         Ok(Self { nanos })
     }
 
+    /// Adds a `Duration` to the current `Instant`, returning an error if the `Duration`
+    /// contains a `DateDuration`.
+    #[inline]
+    pub fn add(&self, duration: Duration) -> TemporalResult<Self> {
+        if !duration.is_time_duration() {
+            return Err(TemporalError::range()
+                .with_message("DateDuration values cannot be added to instant."));
+        }
+        self.add_time_duration(duration.time())
+    }
+
+    /// Adds a `TimeDuration` to `Instant`.
+    #[inline]
+    pub fn add_time_duration(&self, duration: &TimeDuration) -> TemporalResult<Self> {
+        self.add_to_instant(duration)
+    }
+
+    /// Subtract a `Duration` to the current `Instant`, returning an error if the `Duration`
+    /// contains a `DateDuration`.
+    #[inline]
+    pub fn subtract(&self, duration: Duration) -> TemporalResult<Self> {
+        if !duration.is_time_duration() {
+            return Err(TemporalError::range()
+                .with_message("DateDuration values cannot be added to instant."));
+        }
+        self.subtract_time_duration(duration.time())
+    }
+
+    /// Subtracts a `TimeDuration` to `Instant`.
+    #[inline]
+    pub fn subtract_time_duration(&self, duration: &TimeDuration) -> TemporalResult<Self> {
+        self.add_to_instant(&duration.neg())
+    }
+
+    /// Returns a `TimeDuration` representing the duration since provided `Instant`
+    #[inline]
+    pub fn since(
+        &self,
+        other: &Self,
+        rounding_mode: Option<TemporalRoundingMode>,
+        rounding_increment: Option<f64>,
+        largest_unit: Option<TemporalUnit>,
+        smallest_unit: Option<TemporalUnit>,
+    ) -> TemporalResult<TimeDuration> {
+        self.diff_instant(
+            true,
+            other,
+            rounding_mode,
+            rounding_increment,
+            largest_unit,
+            smallest_unit,
+        )
+    }
+
+    /// Returns a `TimeDuration` representing the duration until provided `Instant`
+    #[inline]
+    pub fn until(
+        &self,
+        other: &Self,
+        rounding_mode: Option<TemporalRoundingMode>,
+        rounding_increment: Option<f64>,
+        largest_unit: Option<TemporalUnit>,
+        smallest_unit: Option<TemporalUnit>,
+    ) -> TemporalResult<TimeDuration> {
+        self.diff_instant(
+            false,
+            other,
+            rounding_mode,
+            rounding_increment,
+            largest_unit,
+            smallest_unit,
+        )
+    }
+
+    /// Returns an `Instant` by rounding the current `Instant` according to the provided settings.
+    pub fn round(
+        &self,
+        increment: Option<f64>,
+        unit: TemporalUnit, // smallestUnit is required on Instant::round
+        rounding_mode: Option<TemporalRoundingMode>,
+    ) -> TemporalResult<Self> {
+        let increment = utils::to_rounding_increment(increment)?;
+        let mode = rounding_mode.unwrap_or(TemporalRoundingMode::HalfExpand);
+        let maximum = match unit {
+            TemporalUnit::Hour => 24u64,
+            TemporalUnit::Minute => 24 * 60,
+            TemporalUnit::Second => 24 * 3600,
+            TemporalUnit::Millisecond => MS_PER_DAY as u64,
+            TemporalUnit::Microsecond => MS_PER_DAY as u64 * 1000,
+            TemporalUnit::Nanosecond => NS_PER_DAY as u64,
+            _ => return Err(TemporalError::range().with_message("Invalid roundTo unit provided.")),
+        };
+        // NOTE: to_rounding_increment returns an f64 within a u32 range.
+        utils::validate_temporal_rounding_increment(increment as u32, maximum, true)?;
+
+        let round_result = self.round_instant(increment, unit, mode)?;
+        Self::new(round_result)
+    }
+
     /// Returns the `epochSeconds` value for this `Instant`.
     #[must_use]
     pub fn epoch_seconds(&self) -> f64 {
@@ -101,9 +275,7 @@ impl Instant {
     /// Returns the `epochNanoseconds` value for this `Instant`.
     #[must_use]
     pub fn epoch_nanoseconds(&self) -> f64 {
-        self.nanos
+        self.to_f64()
-            .to_f64()
-            .expect("A validated Instant should be within a valid f64")
     }
 }
 

core/temporal/src/lib.rs

@@ -61,11 +61,9 @@ pub type TemporalResult<T> = Result<T, TemporalError>;
 
 // Relevant numeric constants
 /// Nanoseconds per day constant: 8.64e+13
-#[doc(hidden)]
+pub const NS_PER_DAY: i64 = 86_400_000_000_000;
-pub(crate) const NS_PER_DAY: i64 = 86_400_000_000_000;
 /// Milliseconds per day constant: 8.64e+7
-#[doc(hidden)]
+pub const MS_PER_DAY: i32 = 24 * 60 * 60 * 1000;
-pub(crate) const MS_PER_DAY: i32 = 24 * 60 * 60 * 1000;
 /// Max Instant nanosecond constant
 #[doc(hidden)]
 pub(crate) const NS_MAX_INSTANT: i128 = NS_PER_DAY as i128 * 100_000_000i128;

core/temporal/src/options.rs

@@ -7,17 +7,6 @@ use core::{fmt, str::FromStr};
 
 use crate::TemporalError;
 
-// NOTE: Currently the `DifferenceSetting` is the record returned from 13.47 `GetDifferenceSetting`.
-// This should be reassessed once Instant is added to the builtin `Temporal.Instant`.
-/// The settings for a difference Op
-#[derive(Debug, Clone, Copy)]
-pub struct DifferenceSettings {
-    pub(crate) rounding_mode: TemporalRoundingMode,
-    pub(crate) rounding_increment: f64,
-    pub(crate) largest_unit: TemporalUnit,
-    pub(crate) smallest_unit: TemporalUnit,
-}
-
 // ==== Options enums and methods ====
 
 /// The relevant unit that should be used for the operation that

core/temporal/src/utils.rs

@@ -2,13 +2,32 @@
 
 use crate::{
     options::{TemporalRoundingMode, TemporalUnsignedRoundingMode},
-    MS_PER_DAY,
+    TemporalError, TemporalResult, MS_PER_DAY,
 };
 
 use std::ops::Mul;
 
 // NOTE: Review the below for optimizations and add ALOT of tests.
 
+/// Converts and validates an `Option<f64>` rounding increment value into a valid increment result.
+pub(crate) fn to_rounding_increment(increment: Option<f64>) -> TemporalResult<f64> {
+    let inc = increment.unwrap_or(1.0);
+
+    if !inc.is_finite() {
+        return Err(TemporalError::range().with_message("roundingIncrement must be finite."));
+    }
+
+    let integer = inc.trunc();
+
+    if !(1.0..=1_000_000_000f64).contains(&integer) {
+        return Err(
+            TemporalError::range().with_message("roundingIncrement is not within a valid range.")
+        );
+    }
+
+    Ok(integer)
+}
+
 fn apply_unsigned_rounding_mode(
     x: f64,
     r1: f64,
@@ -91,9 +110,9 @@ pub(crate) fn round_number_to_increment(
     // 4. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, isNegative).
     let unsigned_rounding_mode = rounding_mode.get_unsigned_round_mode(is_negative);
     // 5. Let r1 be the largest integer such that r1 ≤ quotient.
-    let r1 = quotient.ceil();
+    let r1 = quotient.floor();
     // 6. Let r2 be the smallest integer such that r2 > quotient.
-    let r2 = quotient.floor();
+    let r2 = quotient.ceil();
     // 7. Let rounded be ApplyUnsignedRoundingMode(quotient, r1, r2, unsignedRoundingMode).
     let mut rounded = apply_unsigned_rounding_mode(quotient, r1, r2, unsigned_rounding_mode);
     // 8. If isNegative is true, set rounded to -rounded.
@@ -104,6 +123,46 @@ pub(crate) fn round_number_to_increment(
     rounded * increment
 }
 
+/// Rounds provided number assuming that the increment is greater than 0.
+pub(crate) fn round_number_to_increment_as_if_positive(
+    nanos: f64,
+    increment_nanos: f64,
+    rounding_mode: TemporalRoundingMode,
+) -> f64 {
+    // 1. Let quotient be x / increment.
+    let quotient = nanos / increment_nanos;
+    // 2. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, false).
+    let unsigned_rounding_mode = rounding_mode.get_unsigned_round_mode(false);
+    // 3. Let r1 be the largest integer such that r1 ≤ quotient.
+    let r1 = quotient.floor();
+    // 4. Let r2 be the smallest integer such that r2 > quotient.
+    let r2 = quotient.ceil();
+    // 5. Let rounded be ApplyUnsignedRoundingMode(quotient, r1, r2, unsignedRoundingMode).
+    let rounded = apply_unsigned_rounding_mode(quotient, r1, r2, unsigned_rounding_mode);
+    // 6. Return rounded × increment.
+    rounded * increment_nanos
+}
+
+pub(crate) fn validate_temporal_rounding_increment(
+    increment: u32,
+    dividend: u64,
+    inclusive: bool,
+) -> TemporalResult<()> {
+    let max = if inclusive { dividend } else { dividend - 1 };
+
+    if u64::from(increment) > max {
+        return Err(TemporalError::range().with_message("roundingIncrement exceeds maximum."));
+    }
+
+    if dividend.rem_euclid(u64::from(increment)) != 0 {
+        return Err(
+            TemporalError::range().with_message("dividend is not divisble by roundingIncrement.")
+        );
+    }
+
+    Ok(())
+}
+
 // ==== Begin Date Equations ====
 
 pub(crate) const MS_PER_HOUR: f64 = 3_600_000f64;