implement field stuff too

crates/ide_assists/src/handlers/generate_deref.rs

@@ -1,11 +1,13 @@
+use std::fmt::Display;
+
 use ide_db::{helpers::FamousDefs, RootDatabase};
 use syntax::{
     ast::{self, NameOwner},
-    AstNode,
+    AstNode, SyntaxNode,
 };
 
 use crate::{
-    assist_context::{AssistContext, Assists},
+    assist_context::{AssistBuilder, AssistContext, Assists},
     utils::generate_trait_impl_text,
     AssistId, AssistKind,
 };
@@ -36,11 +38,15 @@ use crate::{
 // }
 // ```
 pub(crate) fn generate_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_record_deref(acc, ctx).or_else(|| generate_tuple_deref(acc, ctx))
+}
+
+fn generate_record_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
     let field = ctx.find_node_at_offset::<ast::RecordField>()?;
 
     if existing_deref_impl(&ctx.sema, &strukt).is_some() {
-        cov_mark::hit!(test_add_deref_impl_already_exists);
+        cov_mark::hit!(test_add_record_deref_impl_already_exists);
         return None;
     }
 
@@ -51,7 +57,38 @@ pub(crate) fn generate_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<(
         AssistId("generate_deref", AssistKind::Generate),
         format!("Generate `Deref` impl using `{}`", field_name),
         target,
-        |edit| {
+        |edit| generate_edit(edit, strukt, field_type.syntax(), field_name.syntax()),
+    )
+}
+
+fn generate_tuple_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
+    let field = ctx.find_node_at_offset::<ast::TupleField>()?;
+    let field_list = ctx.find_node_at_offset::<ast::TupleFieldList>()?;
+    let field_list_index =
+        field_list.syntax().children().into_iter().position(|s| &s == field.syntax())?;
+
+    if existing_deref_impl(&ctx.sema, &strukt).is_some() {
+        cov_mark::hit!(test_add_field_deref_impl_already_exists);
+        return None;
+    }
+
+    let field_type = field.ty()?;
+    let target = field.syntax().text_range();
+    acc.add(
+        AssistId("generate_deref", AssistKind::Generate),
+        format!("Generate `Deref` impl using `{}`", field.syntax()),
+        target,
+        |edit| generate_edit(edit, strukt, field_type.syntax(), field_list_index),
+    )
+}
+
+fn generate_edit(
+    edit: &mut AssistBuilder,
+    strukt: ast::Struct,
+    field_type_syntax: &SyntaxNode,
+    field_name: impl Display,
+) {
     let start_offset = strukt.syntax().text_range().end();
     let impl_code = format!(
         r#"    type Target = {0};
@@ -59,18 +96,11 @@ pub(crate) fn generate_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<(
     fn deref(&self) -> &Self::Target {{
         &self.{1}
     }}"#,
-                field_type.syntax(),
-                field_name.syntax()
+        field_type_syntax, field_name
     );
     let strukt_adt = ast::Adt::Struct(strukt);
-            // Q for reviewer: Is there a better way to specify the trait_text, e.g.
-            // - can I have it auto `use std::ops::Deref`, and then just use `Deref` as the trait text?
-            //   Or is there a helper that might detect if `std::ops::Deref` has been used, and pick `Deref`,
-            //   otherwise, pick `std::ops::Deref` for the trait_text.
     let deref_impl = generate_trait_impl_text(&strukt_adt, "std::ops::Deref", &impl_code);
     edit.insert(start_offset, deref_impl);
-        },
-    )
 }
 
 fn existing_deref_impl(
@@ -97,7 +127,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_generate_deref() {
+    fn test_generate_record_deref() {
         check_assist(
             generate_deref,
             r#"struct A { }
@@ -115,6 +145,43 @@ impl std::ops::Deref for B {
         );
     }
 
+    #[test]
+    fn test_generate_field_deref_idx_0() {
+        check_assist(
+            generate_deref,
+            r#"struct A { }
+struct B($0A);"#,
+            r#"struct A { }
+struct B(A);
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}"#,
+        );
+    }
+    #[test]
+    fn test_generate_field_deref_idx_1() {
+        check_assist(
+            generate_deref,
+            r#"struct A { }
+struct B(u8, $0A);"#,
+            r#"struct A { }
+struct B(u8, A);
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.1
+    }
+}"#,
+        );
+    }
+
     fn check_not_applicable(ra_fixture: &str) {
         let fixture = format!(
             "//- /main.rs crate:main deps:core,std\n{}\n{}",
@@ -125,8 +192,8 @@ impl std::ops::Deref for B {
     }
 
     #[test]
-    fn test_generate_deref_not_applicable_if_already_impl() {
-        cov_mark::check!(test_add_deref_impl_already_exists);
+    fn test_generate_record_deref_not_applicable_if_already_impl() {
+        cov_mark::check!(test_add_record_deref_impl_already_exists);
         check_not_applicable(
             r#"struct A { }
 struct B { $0a: A }
@@ -137,6 +204,23 @@ impl std::ops::Deref for B {
     fn deref(&self) -> &Self::Target {
         &self.a
     }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_generate_field_deref_not_applicable_if_already_impl() {
+        cov_mark::check!(test_add_field_deref_impl_already_exists);
+        check_not_applicable(
+            r#"struct A { }
+struct B($0A)
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
 }"#,
         )
     }