refactor(set): prevent rehashing

Author: FlyCloudC

set/linked_hash_set.mbt

@@ -70,7 +70,12 @@ pub fn[K] Set::new(capacity? : Int = 8) -> Set[K] {
 /// Create a hash set from array.
 #as_free_fn
 pub fn[K : Hash + Eq] Set::from_array(arr : Array[K]) -> Set[K] {
-  let m = Set::new(capacity=arr.length())
+  let length = arr.length()
+  let mut capacity = length.next_power_of_two()
+  if length >= calc_grow_threshold(capacity) {
+    capacity *= 2
+  }
+  let m = Set::new(capacity~)
   arr.each(e => m.add(e))
   m
 }
@@ -453,7 +458,11 @@ pub impl[K : Hash + Eq] Eq for Set[K] with equal(self, other) {
 #as_free_fn
 pub fn[K : Hash + Eq] Set::of(arr : FixedArray[K]) -> Set[K] {
   let length = arr.length()
-  let m = Set::new(capacity=length)
+  let mut capacity = length.next_power_of_two()
+  if length >= calc_grow_threshold(capacity) {
+    capacity *= 2
+  }
+  let m = Set::new(capacity~)
   for i in 0..<length {
     let e = arr[i]
     m.add(e)