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Fix copyWithin

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This commit is contained in:
Andrew Morris
2022-05-21 17:29:54 +10:00
parent 55e75669f7
commit 3dc2eb7d8b
1 changed files with 36 additions and 17 deletions
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53
src/vstc/virtual_machine/vs_array.rs
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@@ -149,21 +149,27 @@ static COPY_WITHIN: NativeFunction = NativeFunction {
match this {
Val::Array(array_data) => {
let array_data_mut = Rc::make_mut(array_data);
let len = array_data_mut.elements.len();
let ulen = array_data_mut.elements.len();
if ulen > isize::MAX as usize {
std::panic!("Not implemented: array len exceeds isize");
}
let mut target = match params.get(0) {
None => 0,
Some(p) => to_unchecked_wrapping_index(p, len),
Some(p) => to_unchecked_wrapping_index(p, ulen),
};
let mut start = match params.get(1) {
None => 0,
Some(p) => to_unchecked_wrapping_index(p, len),
Some(p) => to_unchecked_wrapping_index(p, ulen),
};
let end = match params.get(2) {
None => len as isize,
Some(p) => to_unchecked_wrapping_index(p, len),
let ilen = ulen as isize;
let mut end = match params.get(2) {
None => ilen,
Some(p) => to_unchecked_wrapping_index(p, ulen),
};
if target < 0 {
@@ -177,16 +183,8 @@ static COPY_WITHIN: NativeFunction = NativeFunction {
return this.clone();
}
if target > start && target < end {
// Tricky case - make sure we don't read from things we've written
std::panic!("Not implemented");
// 1, 2, 3, 4, 5, 6, 7
// ^--------^
// ^
} else {
// Easy case - no overlap between read and write
while target < len as isize && start < end {
if target <= start || target >= end {
while target < ilen && start < end {
array_data_mut.elements[target as usize] =
array_data_mut.elements[start as usize].clone()
;
@@ -194,8 +192,29 @@ static COPY_WITHIN: NativeFunction = NativeFunction {
target += 1;
start += 1;
}
} else {
// The target is after the start. If we copied from start to target
// and worked forwards we'd overwrite the values we needed later.
// Instead we simply do the copies in the reverse order.
target += copy_len - 1;
end -= 1;
if target >= ilen {
end -= target - ilen + 1;
target = ilen - 1;
}
while target >= 0 && end >= start {
array_data_mut.elements[target as usize] =
array_data_mut.elements[end as usize].clone()
;
target -= 1;
end -= 1;
}
}
return this.clone();
},
_ => std::panic!("Not implemented: exceptions/array indirection")