std::vec: add the fit method to the Vec[T] structure

std/internal/dynar/dynar.jule

@@ -65,8 +65,9 @@ impl Dynar {
             ret true
         }
         unsafe {
+            let size = if self.buff.len <= n { self.buff.len } else { n }
             if self.buff.len > 0 {
-                copy[T](new_heap, self.buff.heap, self.buff.len)
+                copy[T](new_heap, self.buff.heap, size)
             }
             unsafe {
                 integ::delete_array[T](self.buff.heap)

std/vec/vec.jule

@@ -14,7 +14,7 @@ const GROW_FACTOR = 2
 //
 // Deallocates itself when destroyed.
 //
-// Vectors aren't use shared allocation between them.
+// Vectors aren't use shared allocation between themselves.
 // Allocates new space and copies (not deep copy) items into space.
 pub struct Vec[T] {
     mem: Dynar[T]
@@ -55,6 +55,15 @@ impl Vec {
         self.mem.dispose()
     }
 
+    // Set capacity to length.
+    // Removes additional capacity that waiting to use.
+    // Allocates new memory to cut additional capacity.
+    pub fn fit(mut self) {
+        if self.len() != self.cap() {
+            self.resize(self.len())
+        }
+    }
+
     // Returns length.
     pub fn len(self): int {
         ret self.mem.buff.len