crates/ra_assists/src/handlers/add_impl.rs

   1 use ra_syntax::ast::{self, AstNode, NameOwner, TypeParamsOwner};
   2 use stdx::{format_to, SepBy};
   3
   4 use crate::{AssistContext, AssistId, Assists};
   5
   6 // Assist: add_impl
   7 //
   8 // Adds a new inherent impl for a type.
   9 //
  10 // ```
  11 // struct Ctx<T: Clone> {
  12 //     data: T,<|>
  13 // }
  14 // ```
  15 // ->
  16 // ```
  17 // struct Ctx<T: Clone> {
  18 //     data: T,
  19 // }
  20 //
  21 // impl<T: Clone> Ctx<T> {
  22 //     $0
  23 // }
  24 // ```
  25 pub(crate) fn add_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
  26     let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
  27     let name = nominal.name()?;
  28     let target = nominal.syntax().text_range();
  29     acc.add(AssistId("add_impl"), format!("Implement {}", name.text().as_str()), target, |edit| {
  30         let type_params = nominal.type_param_list();
  31         let start_offset = nominal.syntax().text_range().end();
  32         let mut buf = String::new();
  33         buf.push_str("\n\nimpl");
  34         if let Some(type_params) = &type_params {
  35             format_to!(buf, "{}", type_params.syntax());
  36         }
  37         buf.push_str(" ");
  38         buf.push_str(name.text().as_str());
  39         if let Some(type_params) = type_params {
  40             let lifetime_params = type_params
  41                 .lifetime_params()
  42                 .filter_map(|it| it.lifetime_token())
  43                 .map(|it| it.text().clone());
  44             let type_params =
  45                 type_params.type_params().filter_map(|it| it.name()).map(|it| it.text().clone());
  46
  47             let generic_params = lifetime_params.chain(type_params).sep_by(", ");
  48             format_to!(buf, "<{}>", generic_params)
  49         }
  50         match ctx.config.snippet_cap {
  51             Some(cap) => {
  52                 buf.push_str(" {\n    $0\n}");
  53                 edit.insert_snippet(cap, start_offset, buf);
  54             }
  55             None => {
  56                 buf.push_str(" {\n}");
  57                 edit.insert(start_offset, buf);
  58             }
  59         }
  60     })
  61 }
  62
  63 #[cfg(test)]
  64 mod tests {
  65     use crate::tests::{check_assist, check_assist_target};
  66
  67     use super::*;
  68
  69     #[test]
  70     fn test_add_impl() {
  71         check_assist(add_impl, "struct Foo {<|>}\n", "struct Foo {}\n\nimpl Foo {\n    $0\n}\n");
  72         check_assist(
  73             add_impl,
  74             "struct Foo<T: Clone> {<|>}",
  75             "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n    $0\n}",
  76         );
  77         check_assist(
  78             add_impl,
  79             "struct Foo<'a, T: Foo<'a>> {<|>}",
  80             "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n    $0\n}",
  81         );
  82     }
  83
  84     #[test]
  85     fn add_impl_target() {
  86         check_assist_target(
  87             add_impl,
  88             "
  89 struct SomeThingIrrelevant;
  90 /// Has a lifetime parameter
  91 struct Foo<'a, T: Foo<'a>> {<|>}
  92 struct EvenMoreIrrelevant;
  93 ",
  94             "/// Has a lifetime parameter
  95 struct Foo<'a, T: Foo<'a>> {}",
  96         );
  97     }
  98 }