diff options
Diffstat (limited to 'crates/ide_db/src/ty_filter.rs')
-rw-r--r-- | crates/ide_db/src/ty_filter.rs | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/crates/ide_db/src/ty_filter.rs b/crates/ide_db/src/ty_filter.rs new file mode 100644 index 000000000..63a945282 --- /dev/null +++ b/crates/ide_db/src/ty_filter.rs | |||
@@ -0,0 +1,58 @@ | |||
1 | //! This module contains structures for filtering the expected types. | ||
2 | //! Use case for structures in this module is, for example, situation when you need to process | ||
3 | //! only certain `Enum`s. | ||
4 | |||
5 | use crate::RootDatabase; | ||
6 | use hir::{Adt, Semantics, Type}; | ||
7 | use std::iter; | ||
8 | use syntax::ast::{self, make}; | ||
9 | |||
10 | /// Enum types that implement `std::ops::Try` trait. | ||
11 | #[derive(Clone, Copy)] | ||
12 | pub enum TryEnum { | ||
13 | Result, | ||
14 | Option, | ||
15 | } | ||
16 | |||
17 | impl TryEnum { | ||
18 | const ALL: [TryEnum; 2] = [TryEnum::Option, TryEnum::Result]; | ||
19 | |||
20 | /// Returns `Some(..)` if the provided type is an enum that implements `std::ops::Try`. | ||
21 | pub fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> { | ||
22 | let enum_ = match ty.as_adt() { | ||
23 | Some(Adt::Enum(it)) => it, | ||
24 | _ => return None, | ||
25 | }; | ||
26 | TryEnum::ALL.iter().find_map(|&var| { | ||
27 | if &enum_.name(sema.db).to_string() == var.type_name() { | ||
28 | return Some(var); | ||
29 | } | ||
30 | None | ||
31 | }) | ||
32 | } | ||
33 | |||
34 | pub fn happy_case(self) -> &'static str { | ||
35 | match self { | ||
36 | TryEnum::Result => "Ok", | ||
37 | TryEnum::Option => "Some", | ||
38 | } | ||
39 | } | ||
40 | |||
41 | pub fn sad_pattern(self) -> ast::Pat { | ||
42 | match self { | ||
43 | TryEnum::Result => make::tuple_struct_pat( | ||
44 | make::path_unqualified(make::path_segment(make::name_ref("Err"))), | ||
45 | iter::once(make::wildcard_pat().into()), | ||
46 | ) | ||
47 | .into(), | ||
48 | TryEnum::Option => make::ident_pat(make::name("None")).into(), | ||
49 | } | ||
50 | } | ||
51 | |||
52 | fn type_name(self) -> &'static str { | ||
53 | match self { | ||
54 | TryEnum::Result => "Result", | ||
55 | TryEnum::Option => "Option", | ||
56 | } | ||
57 | } | ||
58 | } | ||