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-rw-r--r--crates/ide_assists/src/handlers/generate_deref.rs227
1 files changed, 227 insertions, 0 deletions
diff --git a/crates/ide_assists/src/handlers/generate_deref.rs b/crates/ide_assists/src/handlers/generate_deref.rs
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1use std::fmt::Display;
2
3use ide_db::{helpers::FamousDefs, RootDatabase};
4use syntax::{
5 ast::{self, NameOwner},
6 AstNode, SyntaxNode,
7};
8
9use crate::{
10 assist_context::{AssistBuilder, AssistContext, Assists},
11 utils::generate_trait_impl_text,
12 AssistId, AssistKind,
13};
14
15// Assist: generate_deref
16//
17// Generate `Deref` impl using the given struct field.
18//
19// ```
20// struct A;
21// struct B {
22// $0a: A
23// }
24// ```
25// ->
26// ```
27// struct A;
28// struct B {
29// a: A
30// }
31//
32// impl std::ops::Deref for B {
33// type Target = A;
34//
35// fn deref(&self) -> &Self::Target {
36// &self.a
37// }
38// }
39// ```
40pub(crate) fn generate_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
41 generate_record_deref(acc, ctx).or_else(|| generate_tuple_deref(acc, ctx))
42}
43
44fn generate_record_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
45 let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
46 let field = ctx.find_node_at_offset::<ast::RecordField>()?;
47
48 if existing_deref_impl(&ctx.sema, &strukt).is_some() {
49 cov_mark::hit!(test_add_record_deref_impl_already_exists);
50 return None;
51 }
52
53 let field_type = field.ty()?;
54 let field_name = field.name()?;
55 let target = field.syntax().text_range();
56 acc.add(
57 AssistId("generate_deref", AssistKind::Generate),
58 format!("Generate `Deref` impl using `{}`", field_name),
59 target,
60 |edit| generate_edit(edit, strukt, field_type.syntax(), field_name.syntax()),
61 )
62}
63
64fn generate_tuple_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
65 let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
66 let field = ctx.find_node_at_offset::<ast::TupleField>()?;
67 let field_list = ctx.find_node_at_offset::<ast::TupleFieldList>()?;
68 let field_list_index =
69 field_list.syntax().children().into_iter().position(|s| &s == field.syntax())?;
70
71 if existing_deref_impl(&ctx.sema, &strukt).is_some() {
72 cov_mark::hit!(test_add_field_deref_impl_already_exists);
73 return None;
74 }
75
76 let field_type = field.ty()?;
77 let target = field.syntax().text_range();
78 acc.add(
79 AssistId("generate_deref", AssistKind::Generate),
80 format!("Generate `Deref` impl using `{}`", field.syntax()),
81 target,
82 |edit| generate_edit(edit, strukt, field_type.syntax(), field_list_index),
83 )
84}
85
86fn generate_edit(
87 edit: &mut AssistBuilder,
88 strukt: ast::Struct,
89 field_type_syntax: &SyntaxNode,
90 field_name: impl Display,
91) {
92 let start_offset = strukt.syntax().text_range().end();
93 let impl_code = format!(
94 r#" type Target = {0};
95
96 fn deref(&self) -> &Self::Target {{
97 &self.{1}
98 }}"#,
99 field_type_syntax, field_name
100 );
101 let strukt_adt = ast::Adt::Struct(strukt);
102 let deref_impl = generate_trait_impl_text(&strukt_adt, "std::ops::Deref", &impl_code);
103 edit.insert(start_offset, deref_impl);
104}
105
106fn existing_deref_impl(
107 sema: &'_ hir::Semantics<'_, RootDatabase>,
108 strukt: &ast::Struct,
109) -> Option<()> {
110 let strukt = sema.to_def(strukt)?;
111 let krate = strukt.module(sema.db).krate();
112
113 let deref_trait = FamousDefs(sema, Some(krate)).core_ops_Deref()?;
114 let strukt_type = strukt.ty(sema.db);
115
116 if strukt_type.impls_trait(sema.db, deref_trait, &[]) {
117 Some(())
118 } else {
119 None
120 }
121}
122
123#[cfg(test)]
124mod tests {
125 use crate::tests::{check_assist, check_assist_not_applicable};
126
127 use super::*;
128
129 #[test]
130 fn test_generate_record_deref() {
131 check_assist(
132 generate_deref,
133 r#"struct A { }
134struct B { $0a: A }"#,
135 r#"struct A { }
136struct B { a: A }
137
138impl std::ops::Deref for B {
139 type Target = A;
140
141 fn deref(&self) -> &Self::Target {
142 &self.a
143 }
144}"#,
145 );
146 }
147
148 #[test]
149 fn test_generate_field_deref_idx_0() {
150 check_assist(
151 generate_deref,
152 r#"struct A { }
153struct B($0A);"#,
154 r#"struct A { }
155struct B(A);
156
157impl std::ops::Deref for B {
158 type Target = A;
159
160 fn deref(&self) -> &Self::Target {
161 &self.0
162 }
163}"#,
164 );
165 }
166 #[test]
167 fn test_generate_field_deref_idx_1() {
168 check_assist(
169 generate_deref,
170 r#"struct A { }
171struct B(u8, $0A);"#,
172 r#"struct A { }
173struct B(u8, A);
174
175impl std::ops::Deref for B {
176 type Target = A;
177
178 fn deref(&self) -> &Self::Target {
179 &self.1
180 }
181}"#,
182 );
183 }
184
185 fn check_not_applicable(ra_fixture: &str) {
186 let fixture = format!(
187 "//- /main.rs crate:main deps:core,std\n{}\n{}",
188 ra_fixture,
189 FamousDefs::FIXTURE
190 );
191 check_assist_not_applicable(generate_deref, &fixture)
192 }
193
194 #[test]
195 fn test_generate_record_deref_not_applicable_if_already_impl() {
196 cov_mark::check!(test_add_record_deref_impl_already_exists);
197 check_not_applicable(
198 r#"struct A { }
199struct B { $0a: A }
200
201impl std::ops::Deref for B {
202 type Target = A;
203
204 fn deref(&self) -> &Self::Target {
205 &self.a
206 }
207}"#,
208 )
209 }
210
211 #[test]
212 fn test_generate_field_deref_not_applicable_if_already_impl() {
213 cov_mark::check!(test_add_field_deref_impl_already_exists);
214 check_not_applicable(
215 r#"struct A { }
216struct B($0A)
217
218impl std::ops::Deref for B {
219 type Target = A;
220
221 fn deref(&self) -> &Self::Target {
222 &self.0
223 }
224}"#,
225 )
226 }
227}