aboutsummaryrefslogtreecommitdiff
path: root/crates/assists/src/handlers/replace_impl_trait_with_generic.rs
blob: ff25b61ea2709857969dd871df2a011f9edfdae8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
use syntax::ast::{self, edit::AstNodeEdit, make, AstNode, GenericParamsOwner};

use crate::{AssistContext, AssistId, AssistKind, Assists};

// Assist: replace_impl_trait_with_generic
//
// Replaces `impl Trait` function argument with the named generic.
//
// ```
// fn foo(bar: $0impl Bar) {}
// ```
// ->
// ```
// fn foo<B: Bar>(bar: B) {}
// ```
pub(crate) fn replace_impl_trait_with_generic(
    acc: &mut Assists,
    ctx: &AssistContext,
) -> Option<()> {
    let type_impl_trait = ctx.find_node_at_offset::<ast::ImplTraitType>()?;
    let type_param = type_impl_trait.syntax().parent().and_then(ast::Param::cast)?;
    let type_fn = type_param.syntax().ancestors().find_map(ast::Fn::cast)?;

    let impl_trait_ty = type_impl_trait.type_bound_list()?;

    let target = type_fn.syntax().text_range();
    acc.add(
        AssistId("replace_impl_trait_with_generic", AssistKind::RefactorRewrite),
        "Replace impl trait with generic",
        target,
        |edit| {
            let generic_letter = impl_trait_ty.to_string().chars().next().unwrap().to_string();

            let generic_param_list = type_fn
                .generic_param_list()
                .unwrap_or_else(|| make::generic_param_list(None))
                .append_param(make::generic_param(generic_letter.clone(), Some(impl_trait_ty)));

            let new_type_fn = type_fn
                .replace_descendant::<ast::Type>(type_impl_trait.into(), make::ty(&generic_letter))
                .with_generic_param_list(generic_param_list);

            edit.replace_ast(type_fn.clone(), new_type_fn);
        },
    )
}

#[cfg(test)]
mod tests {
    use super::*;

    use crate::tests::check_assist;

    #[test]
    fn replace_impl_trait_with_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<G>(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<G, B: Bar>(bar: B) {}
            "#,
        );
    }

    #[test]
    fn replace_impl_trait_without_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<B: Bar>(bar: B) {}
            "#,
        );
    }

    #[test]
    fn replace_two_impl_trait_with_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<G>(foo: impl Foo, bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<G, B: Bar>(foo: impl Foo, bar: B) {}
            "#,
        );
    }

    #[test]
    fn replace_impl_trait_with_empty_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<>(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<B: Bar>(bar: B) {}
            "#,
        );
    }

    #[test]
    fn replace_impl_trait_with_empty_multiline_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<
            >(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<B: Bar
            >(bar: B) {}
            "#,
        );
    }

    #[test]
    #[ignore = "This case is very rare but there is no simple solutions to fix it."]
    fn replace_impl_trait_with_exist_generic_letter() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<B>(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<B, C: Bar>(bar: C) {}
            "#,
        );
    }

    #[test]
    fn replace_impl_trait_with_multiline_generic_params() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo<
                G: Foo,
                F,
                H,
            >(bar: $0impl Bar) {}
            "#,
            r#"
            fn foo<
                G: Foo,
                F,
                H, B: Bar
            >(bar: B) {}
            "#,
        );
    }

    #[test]
    fn replace_impl_trait_multiple() {
        check_assist(
            replace_impl_trait_with_generic,
            r#"
            fn foo(bar: $0impl Foo + Bar) {}
            "#,
            r#"
            fn foo<F: Foo + Bar>(bar: F) {}
            "#,
        );
    }
}