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array: add reverse_in_place for performance (#5798)

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yuyi
2020-07-11 19:17:11 +08:00
committed by GitHub
parent b92ce38593
commit fae601fe39
2 changed files with 29 additions and 0 deletions
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15
vlib/builtin/array.v
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@ -400,6 +400,21 @@ pub fn (mut a3 array) push_many(val voidptr, size int) {
a3.len += size
}
pub fn (mut a array) reverse_in_place() {
if a.len < 2 {
return
}
unsafe {
mut tmp_value := malloc(a.element_size)
for i in 0..a.len/2 {
C.memcpy(tmp_value, byteptr(a.data) + i * a.element_size, a.element_size)
C.memcpy(byteptr(a.data) + i * a.element_size, byteptr(a.data) + (a.len-1-i) * a.element_size, a.element_size)
C.memcpy(byteptr(a.data) + (a.len-1-i) * a.element_size, tmp_value, a.element_size)
}
free(tmp_value)
}
}
// array.reverse returns a new array with the elements of
// the original array in reverse order.
pub fn (a array) reverse() array {