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Implement
to_integer_or_infinity from the ECMA spec and use it in `…
…fill` and `slice`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| use super::*; | ||
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| use std::convert::TryFrom; | ||
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| /// Represents the result of ToIntegerOrInfinity operation | ||
| #[derive(Debug, Clone, Copy, PartialEq, Eq)] | ||
| pub enum IntegerOrInfinity { | ||
| Integer(isize), | ||
| Undefined, | ||
| PositiveInfinity, | ||
| NegativeInfinity, | ||
| } | ||
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| impl IntegerOrInfinity { | ||
| /// Represents the algorithm to calculate `relativeStart` (or `k`) in array functions. | ||
| pub fn as_relative_start(self, len: usize) -> usize { | ||
| match self { | ||
| // 1. If relativeStart is -∞, let k be 0. | ||
| IntegerOrInfinity::NegativeInfinity => 0, | ||
| // 2. Else if relativeStart < 0, let k be max(len + relativeStart, 0). | ||
| IntegerOrInfinity::Integer(i) if i < 0 => Self::offset(len, i), | ||
| // 3. Else, let k be min(relativeStart, len). | ||
| IntegerOrInfinity::Integer(i) => (i as usize).min(len), | ||
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| // Special case - postive infinity. `len` is always smaller than +inf, thus from (3) | ||
| IntegerOrInfinity::PositiveInfinity => len, | ||
| // Special case - `undefined` is treated like 0 | ||
| IntegerOrInfinity::Undefined => 0, | ||
| } | ||
| } | ||
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| /// Represents the algorithm to calculate `relativeEnd` (or `final`) in array functions. | ||
| pub fn as_relative_end(self, len: usize) -> usize { | ||
| match self { | ||
| // 1. If end is undefined, let relativeEnd be len | ||
| IntegerOrInfinity::Undefined => len, | ||
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| // 1. cont, else let relativeEnd be ? ToIntegerOrInfinity(end). | ||
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| // 2. If relativeEnd is -∞, let final be 0. | ||
| IntegerOrInfinity::NegativeInfinity => 0, | ||
| // 3. Else if relativeEnd < 0, let final be max(len + relativeEnd, 0). | ||
| IntegerOrInfinity::Integer(i) if i < 0 => Self::offset(len, i), | ||
| // 4. Else, let final be min(relativeEnd, len). | ||
| IntegerOrInfinity::Integer(i) => (i as usize).min(len), | ||
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| // Special case - postive infinity. `len` is always smaller than +inf, thus from (4) | ||
| IntegerOrInfinity::PositiveInfinity => len, | ||
| } | ||
| } | ||
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| fn offset(len: usize, i: isize) -> usize { | ||
| debug_assert!(i < 0); | ||
| if i == isize::MIN { | ||
| len.saturating_sub(isize::MAX as usize).saturating_sub(1) | ||
| } else { | ||
| len.saturating_sub(i.saturating_neg() as usize) | ||
| } | ||
| } | ||
| } | ||
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| impl Value { | ||
| /// Converts argument to an integer, +∞, or -∞. | ||
| /// | ||
| /// See: <https://tc39.es/ecma262/#sec-tointegerorinfinity> | ||
| pub fn to_integer_or_infinity(&self, context: &mut Context) -> Result<IntegerOrInfinity> { | ||
| // Special case - `undefined` | ||
| if self.is_undefined() { | ||
| return Ok(IntegerOrInfinity::Undefined); | ||
| } | ||
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| // 1. Let number be ? ToNumber(argument). | ||
| let number = self.to_number(context)?; | ||
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| // 2. If number is NaN, +0𝔽, or -0𝔽, return 0. | ||
| if number.is_nan() || number == 0.0 || number == -0.0 { | ||
| Ok(IntegerOrInfinity::Integer(0)) | ||
| } else if number.is_infinite() && number.is_sign_positive() { | ||
| // 3. If number is +∞𝔽, return +∞. | ||
| Ok(IntegerOrInfinity::PositiveInfinity) | ||
| } else if number.is_infinite() && number.is_sign_negative() { | ||
| // 4. If number is -∞𝔽, return -∞. | ||
| Ok(IntegerOrInfinity::NegativeInfinity) | ||
| } else { | ||
| // 5. Let integer be floor(abs(ℝ(number))). | ||
| let integer = number.abs().floor(); | ||
| let integer = integer.min(Number::MAX_SAFE_INTEGER) as i64; | ||
| let integer = isize::try_from(integer)?; | ||
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| // 6. If number < +0𝔽, set integer to -integer. | ||
| // 7. Return integer. | ||
| if number < 0.0 { | ||
| Ok(IntegerOrInfinity::Integer(-integer)) | ||
| } else { | ||
| Ok(IntegerOrInfinity::Integer(integer)) | ||
| } | ||
| } | ||
| } | ||
| } |