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@ -112,6 +112,7 @@ impl BuiltIn for Array {
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.method(Self::reduce_right, "reduceRight", 2) |
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.method(Self::keys, "keys", 0) |
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.method(Self::entries, "entries", 0) |
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.method(Self::copy_within, "copyWithin", 3) |
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// Static Methods
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.static_method(Self::is_array, "isArray", 1) |
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.static_method(Self::of, "of", 0) |
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@ -1575,6 +1576,71 @@ impl Array {
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Ok(accumulator) |
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} |
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/// `Array.prototype.copyWithin ( target, start [ , end ] )`
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///
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/// The copyWithin() method shallow copies part of an array to another location
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/// in the same array and returns it without modifying its length.
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///
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/// More information:
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/// - [ECMAScript reference][spec]
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/// - [MDN documentation][mdn]
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///
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/// [spec]: https://tc39.es/ecma262/#sec-array.prototype.copywithin
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/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/copyWithin
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pub(crate) fn copy_within( |
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this: &Value, |
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args: &[Value], |
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context: &mut Context, |
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) -> Result<Value> { |
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enum Direction { |
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Forward, |
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Backward, |
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} |
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let this: Value = this.to_object(context)?.into(); |
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let length = this.get_field("length", context)?.to_length(context)?; |
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let mut to = Self::get_relative_start(context, args.get(0), length)?; |
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let mut from = Self::get_relative_start(context, args.get(1), length)?; |
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let finale = Self::get_relative_end(context, args.get(2), length)?; |
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// saturating sub accounts for the case from > finale, which would cause an overflow
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// can skip the check for length - to, because we assert to <= length in get_relative_start
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let count = (finale.saturating_sub(from)).min(length - to); |
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let direction = if from < to && to < from + count { |
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from += count - 1; |
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to += count - 1; |
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Direction::Backward |
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} else { |
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Direction::Forward |
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}; |
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// the original spec uses a while-loop from count to 1,
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// but count is not used inside the loop, so we can safely replace it
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// with a for-loop from 0 to count - 1
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for _ in 0..count { |
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if this.has_field(from) { |
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let val = this.get_field(from, context)?; |
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this.set_field(to, val, true, context)?; |
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} else { |
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this.remove_property(to); |
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} |
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match direction { |
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Direction::Forward => { |
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from += 1; |
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to += 1; |
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} |
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Direction::Backward => { |
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from -= 1; |
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to -= 1; |
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} |
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} |
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} |
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Ok(this) |
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} |
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/// `Array.prototype.values( )`
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///
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/// The values method returns an iterable that iterates over the values in the array.
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