crates/ide-assists/src/handlers/generate_new.rs - third_party/github.com/rust-lang/rust-analyzer - Git at Google

 use ide_db::{
     imports::import_assets::item_for_path_search, use_trivial_constructor::use_trivial_constructor,
 };
 use syntax::{
     ast::{self, AstNode, HasName, HasVisibility, StructKind, edit_in_place::Indent, make},
     ted,
 };

 use crate::{
     AssistContext, AssistId, AssistKind, Assists,
     utils::{find_struct_impl, generate_impl},
 };

 // Assist: generate_new
 //
 // Adds a `fn new` for a type.
 //
 // ```
 // struct Ctx<T: Clone> {
 //      data: T,$0
 // }
 // ```
 // ->
 // ```
 // struct Ctx<T: Clone> {
 //      data: T,
 // }
 //
 // impl<T: Clone> Ctx<T> {
 //     fn $0new(data: T) -> Self {
 //         Self { data }
 //     }
 // }
 // ```
 pub(crate) fn generate_new(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
     let strukt = ctx.find_node_at_offset::<ast::Struct>()?;

     // We want to only apply this to non-union structs with named fields
     let field_list = match strukt.kind() {
         StructKind::Record(named) => named,
         _ => return None,
     };

     // Return early if we've found an existing new fn
     let impl_def =
         find_struct_impl(ctx, &ast::Adt::Struct(strukt.clone()), &[String::from("new")])?;

     let current_module = ctx.sema.scope(strukt.syntax())?.module();

     let target = strukt.syntax().text_range();
     acc.add(AssistId("generate_new", AssistKind::Generate), "Generate `new`", target, |builder| {
         let trivial_constructors = field_list
             .fields()
             .map(|f| {
                 let name = f.name()?;

                 let ty = ctx.sema.resolve_type(&f.ty()?)?;

                 let item_in_ns = hir::ItemInNs::from(hir::ModuleDef::from(ty.as_adt()?));

                 let type_path = current_module.find_path(
                     ctx.sema.db,
                     item_for_path_search(ctx.sema.db, item_in_ns)?,
                     ctx.config.import_path_config(),
                 )?;

                 let edition = current_module.krate().edition(ctx.db());

                 let expr = use_trivial_constructor(
                     ctx.sema.db,
                     ide_db::helpers::mod_path_to_ast(&type_path, edition),
                     &ty,
                     edition,
                 )?;

                 Some(make::record_expr_field(make::name_ref(&name.text()), Some(expr)))
             })
             .collect::<Vec<_>>();

         let params = field_list.fields().enumerate().filter_map(|(i, f)| {
             if trivial_constructors[i].is_none() {
                 let name = f.name()?;
                 let ty = f.ty()?;

                 Some(make::param(make::ident_pat(false, false, name).into(), ty))
             } else {
                 None
             }
         });
         let params = make::param_list(None, params);

         let fields = field_list.fields().enumerate().filter_map(|(i, f)| {
             let constructor = trivial_constructors[i].clone();
             if constructor.is_some() {
                 constructor
             } else {
                 Some(make::record_expr_field(make::name_ref(&f.name()?.text()), None))
             }
         });
         let fields = make::record_expr_field_list(fields);

         let record_expr = make::record_expr(make::ext::ident_path("Self"), fields);
         let body = make::block_expr(None, Some(record_expr.into()));

         let ret_type = make::ret_type(make::ty_path(make::ext::ident_path("Self")));

         let fn_ = make::fn_(
             strukt.visibility(),
             make::name("new"),
             None,
             None,
             params,
             body,
             Some(ret_type),
             false,
             false,
             false,
             false,
         )
         .clone_for_update();
         fn_.indent(1.into());

         // Add a tabstop before the name
         if let Some(cap) = ctx.config.snippet_cap {
             if let Some(name) = fn_.name() {
                 builder.add_tabstop_before(cap, name);
             }
         }

         // Get the mutable version of the impl to modify
         let impl_def = if let Some(impl_def) = impl_def {
             builder.make_mut(impl_def)
         } else {
             // Generate a new impl to add the method to
             let impl_def = generate_impl(&ast::Adt::Struct(strukt.clone()));

             // Insert it after the adt
             let strukt = builder.make_mut(strukt.clone());

             ted::insert_all_raw(
                 ted::Position::after(strukt.syntax()),
                 vec![make::tokens::blank_line().into(), impl_def.syntax().clone().into()],
             );

             impl_def
         };

         // Add the `new` method at the start of the impl
         impl_def.get_or_create_assoc_item_list().add_item_at_start(fn_.into());
     })
 }

 #[cfg(test)]
 mod tests {
     use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};

     use super::*;

     #[test]
     fn test_generate_new_with_zst_fields() {
         check_assist(
             generate_new,
             r#"
 struct Empty;

 struct Foo { empty: Empty $0}
 "#,
             r#"
 struct Empty;

 struct Foo { empty: Empty }

 impl Foo {
     fn $0new() -> Self {
         Self { empty: Empty }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Empty;

 struct Foo { baz: String, empty: Empty $0}
 "#,
             r#"
 struct Empty;

 struct Foo { baz: String, empty: Empty }

 impl Foo {
     fn $0new(baz: String) -> Self {
         Self { baz, empty: Empty }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 enum Empty { Bar }

 struct Foo { empty: Empty $0}
 "#,
             r#"
 enum Empty { Bar }

 struct Foo { empty: Empty }

 impl Foo {
     fn $0new() -> Self {
         Self { empty: Empty::Bar }
     }
 }
 "#,
         );

         // make sure the assist only works on unit variants
         check_assist(
             generate_new,
             r#"
 struct Empty {}

 struct Foo { empty: Empty $0}
 "#,
             r#"
 struct Empty {}

 struct Foo { empty: Empty }

 impl Foo {
     fn $0new(empty: Empty) -> Self {
         Self { empty }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 enum Empty { Bar {} }

 struct Foo { empty: Empty $0}
 "#,
             r#"
 enum Empty { Bar {} }

 struct Foo { empty: Empty }

 impl Foo {
     fn $0new(empty: Empty) -> Self {
         Self { empty }
     }
 }
 "#,
         );
     }

     #[test]
     fn test_generate_new() {
         check_assist(
             generate_new,
             r#"
 struct Foo {$0}
 "#,
             r#"
 struct Foo {}

 impl Foo {
     fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Foo<T: Clone> {$0}
 "#,
             r#"
 struct Foo<T: Clone> {}

 impl<T: Clone> Foo<T> {
     fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Foo<'a, T: Foo<'a>> {$0}
 "#,
             r#"
 struct Foo<'a, T: Foo<'a>> {}

 impl<'a, T: Foo<'a>> Foo<'a, T> {
     fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Foo { baz: String $0}
 "#,
             r#"
 struct Foo { baz: String }

 impl Foo {
     fn $0new(baz: String) -> Self {
         Self { baz }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Foo { baz: String, qux: Vec<i32> $0}
 "#,
             r#"
 struct Foo { baz: String, qux: Vec<i32> }

 impl Foo {
     fn $0new(baz: String, qux: Vec<i32>) -> Self {
         Self { baz, qux }
     }
 }
 "#,
         );
     }

     #[test]
     fn check_that_visibility_modifiers_dont_get_brought_in() {
         check_assist(
             generate_new,
             r#"
 struct Foo { pub baz: String, pub qux: Vec<i32> $0}
 "#,
             r#"
 struct Foo { pub baz: String, pub qux: Vec<i32> }

 impl Foo {
     fn $0new(baz: String, qux: Vec<i32>) -> Self {
         Self { baz, qux }
     }
 }
 "#,
         );
     }

     #[test]
     fn check_it_reuses_existing_impls() {
         check_assist(
             generate_new,
             r#"
 struct Foo {$0}

 impl Foo {}
 "#,
             r#"
 struct Foo {}

 impl Foo {
     fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 struct Foo {$0}

 impl Foo {
     fn qux(&self) {}
 }
 "#,
             r#"
 struct Foo {}

 impl Foo {
     fn $0new() -> Self {
         Self {  }
     }

     fn qux(&self) {}
 }
 "#,
         );

         check_assist(
             generate_new,
             r#"
 struct Foo {$0}

 impl Foo {
     fn qux(&self) {}
     fn baz() -> i32 {
         5
     }
 }
 "#,
             r#"
 struct Foo {}

 impl Foo {
     fn $0new() -> Self {
         Self {  }
     }

     fn qux(&self) {}
     fn baz() -> i32 {
         5
     }
 }
 "#,
         );
     }

     #[test]
     fn check_visibility_of_new_fn_based_on_struct() {
         check_assist(
             generate_new,
             r#"
 pub struct Foo {$0}
 "#,
             r#"
 pub struct Foo {}

 impl Foo {
     pub fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
         check_assist(
             generate_new,
             r#"
 pub(crate) struct Foo {$0}
 "#,
             r#"
 pub(crate) struct Foo {}

 impl Foo {
     pub(crate) fn $0new() -> Self {
         Self {  }
     }
 }
 "#,
         );
     }

     #[test]
     fn generate_new_not_applicable_if_fn_exists() {
         check_assist_not_applicable(
             generate_new,
             r#"
 struct Foo {$0}

 impl Foo {
     fn new() -> Self {
         Self
     }
 }
 "#,
         );

         check_assist_not_applicable(
             generate_new,
             r#"
 struct Foo {$0}

 impl Foo {
     fn New() -> Self {
         Self
     }
 }
 "#,
         );
     }

     #[test]
     fn generate_new_target() {
         check_assist_target(
             generate_new,
             r#"
 struct SomeThingIrrelevant;
 /// Has a lifetime parameter
 struct Foo<'a, T: Foo<'a>> {$0}
 struct EvenMoreIrrelevant;
 "#,
             "/// Has a lifetime parameter
 struct Foo<'a, T: Foo<'a>> {}",
         );
     }

     #[test]
     fn test_unrelated_new() {
         check_assist(
             generate_new,
             r#"
 pub struct AstId<N: AstNode> {
     file_id: HirFileId,
     file_ast_id: FileAstId<N>,
 }

 impl<N: AstNode> AstId<N> {
     pub fn new(file_id: HirFileId, file_ast_id: FileAstId<N>) -> AstId<N> {
         AstId { file_id, file_ast_id }
     }
 }

 pub struct Source<T> {
     pub file_id: HirFileId,$0
     pub ast: T,
 }

 impl<T> Source<T> {
     pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
         Source { file_id: self.file_id, ast: f(self.ast) }
     }
 }
 "#,
             r#"
 pub struct AstId<N: AstNode> {
     file_id: HirFileId,
     file_ast_id: FileAstId<N>,
 }

 impl<N: AstNode> AstId<N> {
     pub fn new(file_id: HirFileId, file_ast_id: FileAstId<N>) -> AstId<N> {
         AstId { file_id, file_ast_id }
     }
 }

 pub struct Source<T> {
     pub file_id: HirFileId,
     pub ast: T,
 }

 impl<T> Source<T> {
     pub fn $0new(file_id: HirFileId, ast: T) -> Self {
         Self { file_id, ast }
     }

     pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
         Source { file_id: self.file_id, ast: f(self.ast) }
     }
 }
 "#,
         );
     }
 }
	use ide_db::{
	imports::import_assets::item_for_path_search, use_trivial_constructor::use_trivial_constructor,
	};
	use syntax::{
	ast::{self, AstNode, HasName, HasVisibility, StructKind, edit_in_place::Indent, make},
	ted,
	};

	use crate::{
	AssistContext, AssistId, AssistKind, Assists,
	utils::{find_struct_impl, generate_impl},
	};

	// Assist: generate_new
	//
	// Adds a `fn new` for a type.
	//
	// ```
	// struct Ctx<T: Clone> {
	// data: T,$0
	// }
	// ```
	// ->
	// ```
	// struct Ctx<T: Clone> {
	// data: T,
	// }
	//
	// impl<T: Clone> Ctx<T> {
	// fn $0new(data: T) -> Self {
	// Self { data }
	// }
	// }
	// ```
	pub(crate) fn generate_new(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
	let strukt = ctx.find_node_at_offset::<ast::Struct>()?;

	// We want to only apply this to non-union structs with named fields
	let field_list = match strukt.kind() {
	StructKind::Record(named) => named,
	_ => return None,
	};

	// Return early if we've found an existing new fn
	let impl_def =
	find_struct_impl(ctx, &ast::Adt::Struct(strukt.clone()), &[String::from("new")])?;

	let current_module = ctx.sema.scope(strukt.syntax())?.module();

	let target = strukt.syntax().text_range();
	acc.add(AssistId("generate_new", AssistKind::Generate), "Generate `new`", target, \|builder\| {
	let trivial_constructors = field_list
	.fields()
	.map(\|f\| {
	let name = f.name()?;

	let ty = ctx.sema.resolve_type(&f.ty()?)?;

	let item_in_ns = hir::ItemInNs::from(hir::ModuleDef::from(ty.as_adt()?));

	let type_path = current_module.find_path(
	ctx.sema.db,
	item_for_path_search(ctx.sema.db, item_in_ns)?,
	ctx.config.import_path_config(),
	)?;

	let edition = current_module.krate().edition(ctx.db());

	let expr = use_trivial_constructor(
	ctx.sema.db,
	ide_db::helpers::mod_path_to_ast(&type_path, edition),
	&ty,
	edition,
	)?;

	Some(make::record_expr_field(make::name_ref(&name.text()), Some(expr)))
	})
	.collect::<Vec<_>>();

	let params = field_list.fields().enumerate().filter_map(\|(i, f)\| {
	if trivial_constructors[i].is_none() {
	let name = f.name()?;
	let ty = f.ty()?;

	Some(make::param(make::ident_pat(false, false, name).into(), ty))
	} else {
	None
	}
	});
	let params = make::param_list(None, params);

	let fields = field_list.fields().enumerate().filter_map(\|(i, f)\| {
	let constructor = trivial_constructors[i].clone();
	if constructor.is_some() {
	constructor
	} else {
	Some(make::record_expr_field(make::name_ref(&f.name()?.text()), None))
	}
	});
	let fields = make::record_expr_field_list(fields);

	let record_expr = make::record_expr(make::ext::ident_path("Self"), fields);
	let body = make::block_expr(None, Some(record_expr.into()));

	let ret_type = make::ret_type(make::ty_path(make::ext::ident_path("Self")));

	let fn_ = make::fn_(
	strukt.visibility(),
	make::name("new"),
	None,
	None,
	params,
	body,
	Some(ret_type),
	false,
	false,
	false,
	false,
	)
	.clone_for_update();
	fn_.indent(1.into());

	// Add a tabstop before the name
	if let Some(cap) = ctx.config.snippet_cap {
	if let Some(name) = fn_.name() {
	builder.add_tabstop_before(cap, name);
	}
	}

	// Get the mutable version of the impl to modify
	let impl_def = if let Some(impl_def) = impl_def {
	builder.make_mut(impl_def)
	} else {
	// Generate a new impl to add the method to
	let impl_def = generate_impl(&ast::Adt::Struct(strukt.clone()));

	// Insert it after the adt
	let strukt = builder.make_mut(strukt.clone());

	ted::insert_all_raw(
	ted::Position::after(strukt.syntax()),
	vec![make::tokens::blank_line().into(), impl_def.syntax().clone().into()],
	);

	impl_def
	};

	// Add the `new` method at the start of the impl
	impl_def.get_or_create_assoc_item_list().add_item_at_start(fn_.into());
	})
	}

	#[cfg(test)]
	mod tests {
	use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};

	use super::*;

	#[test]
	fn test_generate_new_with_zst_fields() {
	check_assist(
	generate_new,
	r#"
	struct Empty;

	struct Foo { empty: Empty $0}
	"#,
	r#"
	struct Empty;

	struct Foo { empty: Empty }

	impl Foo {
	fn $0new() -> Self {
	Self { empty: Empty }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Empty;

	struct Foo { baz: String, empty: Empty $0}
	"#,
	r#"
	struct Empty;

	struct Foo { baz: String, empty: Empty }

	impl Foo {
	fn $0new(baz: String) -> Self {
	Self { baz, empty: Empty }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	enum Empty { Bar }

	struct Foo { empty: Empty $0}
	"#,
	r#"
	enum Empty { Bar }

	struct Foo { empty: Empty }

	impl Foo {
	fn $0new() -> Self {
	Self { empty: Empty::Bar }
	}
	}
	"#,
	);

	// make sure the assist only works on unit variants
	check_assist(
	generate_new,
	r#"
	struct Empty {}

	struct Foo { empty: Empty $0}
	"#,
	r#"
	struct Empty {}

	struct Foo { empty: Empty }

	impl Foo {
	fn $0new(empty: Empty) -> Self {
	Self { empty }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	enum Empty { Bar {} }

	struct Foo { empty: Empty $0}
	"#,
	r#"
	enum Empty { Bar {} }

	struct Foo { empty: Empty }

	impl Foo {
	fn $0new(empty: Empty) -> Self {
	Self { empty }
	}
	}
	"#,
	);
	}

	#[test]
	fn test_generate_new() {
	check_assist(
	generate_new,
	r#"
	struct Foo {$0}
	"#,
	r#"
	struct Foo {}

	impl Foo {
	fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Foo<T: Clone> {$0}
	"#,
	r#"
	struct Foo<T: Clone> {}

	impl<T: Clone> Foo<T> {
	fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Foo<'a, T: Foo<'a>> {$0}
	"#,
	r#"
	struct Foo<'a, T: Foo<'a>> {}

	impl<'a, T: Foo<'a>> Foo<'a, T> {
	fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Foo { baz: String $0}
	"#,
	r#"
	struct Foo { baz: String }

	impl Foo {
	fn $0new(baz: String) -> Self {
	Self { baz }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Foo { baz: String, qux: Vec<i32> $0}
	"#,
	r#"
	struct Foo { baz: String, qux: Vec<i32> }

	impl Foo {
	fn $0new(baz: String, qux: Vec<i32>) -> Self {
	Self { baz, qux }
	}
	}
	"#,
	);
	}

	#[test]
	fn check_that_visibility_modifiers_dont_get_brought_in() {
	check_assist(
	generate_new,
	r#"
	struct Foo { pub baz: String, pub qux: Vec<i32> $0}
	"#,
	r#"
	struct Foo { pub baz: String, pub qux: Vec<i32> }

	impl Foo {
	fn $0new(baz: String, qux: Vec<i32>) -> Self {
	Self { baz, qux }
	}
	}
	"#,
	);
	}

	#[test]
	fn check_it_reuses_existing_impls() {
	check_assist(
	generate_new,
	r#"
	struct Foo {$0}

	impl Foo {}
	"#,
	r#"
	struct Foo {}

	impl Foo {
	fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	struct Foo {$0}

	impl Foo {
	fn qux(&self) {}
	}
	"#,
	r#"
	struct Foo {}

	impl Foo {
	fn $0new() -> Self {
	Self { }
	}

	fn qux(&self) {}
	}
	"#,
	);

	check_assist(
	generate_new,
	r#"
	struct Foo {$0}

	impl Foo {
	fn qux(&self) {}
	fn baz() -> i32 {
	5
	}
	}
	"#,
	r#"
	struct Foo {}

	impl Foo {
	fn $0new() -> Self {
	Self { }
	}

	fn qux(&self) {}
	fn baz() -> i32 {
	5
	}
	}
	"#,
	);
	}

	#[test]
	fn check_visibility_of_new_fn_based_on_struct() {
	check_assist(
	generate_new,
	r#"
	pub struct Foo {$0}
	"#,
	r#"
	pub struct Foo {}

	impl Foo {
	pub fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	check_assist(
	generate_new,
	r#"
	pub(crate) struct Foo {$0}
	"#,
	r#"
	pub(crate) struct Foo {}

	impl Foo {
	pub(crate) fn $0new() -> Self {
	Self { }
	}
	}
	"#,
	);
	}

	#[test]
	fn generate_new_not_applicable_if_fn_exists() {
	check_assist_not_applicable(
	generate_new,
	r#"
	struct Foo {$0}

	impl Foo {
	fn new() -> Self {
	Self
	}
	}
	"#,
	);

	check_assist_not_applicable(
	generate_new,
	r#"
	struct Foo {$0}

	impl Foo {
	fn New() -> Self {
	Self
	}
	}
	"#,
	);
	}

	#[test]
	fn generate_new_target() {
	check_assist_target(
	generate_new,
	r#"
	struct SomeThingIrrelevant;
	/// Has a lifetime parameter
	struct Foo<'a, T: Foo<'a>> {$0}
	struct EvenMoreIrrelevant;
	"#,
	"/// Has a lifetime parameter
	struct Foo<'a, T: Foo<'a>> {}",
	);
	}

	#[test]
	fn test_unrelated_new() {
	check_assist(
	generate_new,
	r#"
	pub struct AstId<N: AstNode> {
	file_id: HirFileId,
	file_ast_id: FileAstId<N>,
	}

	impl<N: AstNode> AstId<N> {
	pub fn new(file_id: HirFileId, file_ast_id: FileAstId<N>) -> AstId<N> {
	AstId { file_id, file_ast_id }
	}
	}

	pub struct Source<T> {
	pub file_id: HirFileId,$0
	pub ast: T,
	}

	impl<T> Source<T> {
	pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
	Source { file_id: self.file_id, ast: f(self.ast) }
	}
	}
	"#,
	r#"
	pub struct AstId<N: AstNode> {
	file_id: HirFileId,
	file_ast_id: FileAstId<N>,
	}

	impl<N: AstNode> AstId<N> {
	pub fn new(file_id: HirFileId, file_ast_id: FileAstId<N>) -> AstId<N> {
	AstId { file_id, file_ast_id }
	}
	}

	pub struct Source<T> {
	pub file_id: HirFileId,
	pub ast: T,
	}

	impl<T> Source<T> {
	pub fn $0new(file_id: HirFileId, ast: T) -> Self {
	Self { file_id, ast }
	}

	pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
	Source { file_id: self.file_id, ast: f(self.ast) }
	}
	}
	"#,
	);
	}
	}