crates/ra_assists/src/add_impl.rs

   1 use join_to_string::join;
   2 use hir::db::HirDatabase;
   3 use ra_syntax::{
   4     ast::{self, AstNode, AstToken, NameOwner, TypeParamsOwner},
   5     TextUnit,
   6 };
   7
   8 use crate::{AssistCtx, Assist};
   9
  10 pub(crate) fn add_impl(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
  11     let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
  12     let name = nominal.name()?;
  13     ctx.build("add impl", |edit| {
  14         edit.target(nominal.syntax().range());
  15         let type_params = nominal.type_param_list();
  16         let start_offset = nominal.syntax().range().end();
  17         let mut buf = String::new();
  18         buf.push_str("\n\nimpl");
  19         if let Some(type_params) = type_params {
  20             type_params.syntax().text().push_to(&mut buf);
  21         }
  22         buf.push_str(" ");
  23         buf.push_str(name.text().as_str());
  24         if let Some(type_params) = type_params {
  25             let lifetime_params =
  26                 type_params.lifetime_params().filter_map(|it| it.lifetime()).map(|it| it.text());
  27             let type_params =
  28                 type_params.type_params().filter_map(|it| it.name()).map(|it| it.text());
  29             join(lifetime_params.chain(type_params)).surround_with("<", ">").to_buf(&mut buf);
  30         }
  31         buf.push_str(" {\n");
  32         edit.set_cursor(start_offset + TextUnit::of_str(&buf));
  33         buf.push_str("\n}");
  34         edit.insert(start_offset, buf);
  35     })
  36 }
  37
  38 #[cfg(test)]
  39 mod tests {
  40     use super::*;
  41     use crate::helpers::{check_assist, check_assist_target};
  42
  43     #[test]
  44     fn test_add_impl() {
  45         check_assist(add_impl, "struct Foo {<|>}\n", "struct Foo {}\n\nimpl Foo {\n<|>\n}\n");
  46         check_assist(
  47             add_impl,
  48             "struct Foo<T: Clone> {<|>}",
  49             "struct Foo<T: Clone> {}\n\nimpl<T: Clone> Foo<T> {\n<|>\n}",
  50         );
  51         check_assist(
  52             add_impl,
  53             "struct Foo<'a, T: Foo<'a>> {<|>}",
  54             "struct Foo<'a, T: Foo<'a>> {}\n\nimpl<'a, T: Foo<'a>> Foo<'a, T> {\n<|>\n}",
  55         );
  56     }
  57
  58     #[test]
  59     fn add_impl_target() {
  60         check_assist_target(
  61             add_impl,
  62             "
  63 struct SomeThingIrrelevant;
  64 /// Has a lifetime parameter
  65 struct Foo<'a, T: Foo<'a>> {<|>}
  66 struct EvenMoreIrrelevant;
  67 ",
  68             "/// Has a lifetime parameter
  69 struct Foo<'a, T: Foo<'a>> {}",
  70         );
  71     }
  72 }