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comparison rust/hg-core/src/dirstate_tree/owning.rs @ 48084:3d0a9c6e614d

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dirstate: Remove the Rust abstraction DirstateMapMethods This Rust trait used to exist in order to allow the DirstateMap class exposed to Python to be backed by either of two implementations: one similar to the Python implementation based on a "flat" `HashMap<HgPathBuf, DirstateEntry>`, and the newer one based on a tree of nodes matching the directory structure of tracked files. A boxed trait object was used with dynamic dispatch. With the flat implementation removed and only the tree one remaining, this abstraction is not useful anymore and the concrete type can be stored directly. It remains that the trait was implemented separately for `DirstateMap<'_>` (which takes a lifetime parameter) and `OwningDirstateMap` (whose job is to wrap the former and hide the lifetime parameter), with the latter impl only forwarding calls. This changeset also removes this forwarding. Instead, the methods formerly of the `DirstateMapMethods` trait are now inherent methods implemented for `OwningDirstateMap` (where they will actually be used) but in the module that defines `DirstateMap`. This unusual setup gives access to the private fields of `DirstateMap` from those methods. Differential Revision: https://phab.mercurial-scm.org/D11517
author Simon Sapin <simon.sapin@octobus.net>
date Mon, 27 Sep 2021 13:52:49 +0200
parents 37a41267d000
children d1210d56008b
comparison
equal deleted inserted replaced
48083:bf8837e3d7ce 48084:3d0a9c6e614d
42 let ptr: *mut () = ptr.cast(); 42 let ptr: *mut () = ptr.cast();
43 43
44 Self { on_disk, ptr } 44 Self { on_disk, ptr }
45 } 45 }
46 46
47 pub fn get_mut_pair<'a>( 47 pub fn get_pair_mut<'a>(
48 &'a mut self, 48 &'a mut self,
49 ) -> (&'a [u8], &'a mut DirstateMap<'a>) { 49 ) -> (&'a [u8], &'a mut DirstateMap<'a>) {
50 // SAFETY: We cast the type-erased pointer back to the same type it had 50 // SAFETY: We cast the type-erased pointer back to the same type it had
51 // in `new`, except with a different lifetime parameter. This time we 51 // in `new`, except with a different lifetime parameter. This time we
52 // connect the lifetime to that of `self`. This cast is valid because 52 // connect the lifetime to that of `self`. This cast is valid because
58 // new `&mut` to that of `self`. This is valid because the 58 // new `&mut` to that of `self`. This is valid because the
59 // raw pointer is to a boxed value, and `self` owns that box. 59 // raw pointer is to a boxed value, and `self` owns that box.
60 (&self.on_disk, unsafe { &mut *ptr }) 60 (&self.on_disk, unsafe { &mut *ptr })
61 } 61 }
62 62
63 pub fn get_mut<'a>(&'a mut self) -> &'a mut DirstateMap<'a> { 63 pub fn get_map_mut<'a>(&'a mut self) -> &'a mut DirstateMap<'a> {
64 self.get_mut_pair().1 64 self.get_pair_mut().1
65 } 65 }
66 66
67 pub fn get<'a>(&'a self) -> &'a DirstateMap<'a> { 67 pub fn get_map<'a>(&'a self) -> &'a DirstateMap<'a> {
68 // SAFETY: same reasoning as in `get_mut` above. 68 // SAFETY: same reasoning as in `get_mut` above.
69 let ptr: *mut DirstateMap<'a> = self.ptr.cast(); 69 let ptr: *mut DirstateMap<'a> = self.ptr.cast();
70 unsafe { &*ptr } 70 unsafe { &*ptr }
71 } 71 }
72 72