30 lines
1011 B
Markdown
30 lines
1011 B
Markdown
% Deallocating
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Next we should implement Drop so that we don't massively leak tons of resources.
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The easiest way is to just call `pop` until it yields None, and then deallocate
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our buffer. Note that calling `pop` is uneeded if `T: !Drop`. In theory we can
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ask Rust if T needs_drop and omit the calls to `pop`. However in practice LLVM
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is *really* good at removing simple side-effect free code like this, so I wouldn't
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bother unless you notice it's not being stripped (in this case it is).
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We must not call `heap::deallocate` when `self.cap == 0`, as in this case we haven't
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actually allocated any memory.
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```rust
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impl<T> Drop for Vec<T> {
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fn drop(&mut self) {
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if self.cap != 0 {
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while let Some(_) = self.pop() { }
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let align = mem::min_align_of::<T>();
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let elem_size = mem::size_of::<T>();
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let num_bytes = elem_size * self.cap;
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unsafe {
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heap::deallocate(*self.ptr, num_bytes, align);
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}
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}
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}
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}
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```
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