use hir::Adt; use ra_syntax::{ ast::{ self, AstNode, NameOwner, StructKind, TypeAscriptionOwner, TypeParamsOwner, VisibilityOwner, }, T, }; use stdx::{format_to, SepBy}; use crate::{AssistContext, AssistId, Assists}; // Assist: add_new // // Adds a new inherent impl for a type. // // ``` // struct Ctx { // data: T,<|> // } // ``` // -> // ``` // struct Ctx { // data: T, // } // // impl Ctx { // fn $0new(data: T) -> Self { Self { data } } // } // // ``` pub(crate) fn add_new(acc: &mut Assists, ctx: &AssistContext) -> Option<()> { let strukt = ctx.find_node_at_offset::()?; // 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, &strukt)?; let target = strukt.syntax().text_range(); acc.add(AssistId("add_new"), "Add default constructor", target, |builder| { let mut buf = String::with_capacity(512); if impl_def.is_some() { buf.push('\n'); } let vis = strukt.visibility().map_or(String::new(), |v| format!("{} ", v)); let params = field_list .fields() .filter_map(|f| { Some(format!("{}: {}", f.name()?.syntax(), f.ascribed_type()?.syntax())) }) .sep_by(", "); let fields = field_list.fields().filter_map(|f| f.name()).sep_by(", "); format_to!(buf, " {}fn new({}) -> Self {{ Self {{ {} }} }}", vis, params, fields); let start_offset = impl_def .and_then(|impl_def| { buf.push('\n'); let start = impl_def .syntax() .descendants_with_tokens() .find(|t| t.kind() == T!['{'])? .text_range() .end(); Some(start) }) .unwrap_or_else(|| { buf = generate_impl_text(&strukt, &buf); strukt.syntax().text_range().end() }); match ctx.config.snippet_cap { None => builder.insert(start_offset, buf), Some(cap) => { buf = buf.replace("fn new", "fn $0new"); builder.insert_snippet(cap, start_offset, buf); } } }) } // Generates the surrounding `impl Type { }` including type and lifetime // parameters fn generate_impl_text(strukt: &ast::StructDef, code: &str) -> String { let type_params = strukt.type_param_list(); let mut buf = String::with_capacity(code.len()); buf.push_str("\n\nimpl"); if let Some(type_params) = &type_params { format_to!(buf, "{}", type_params.syntax()); } buf.push_str(" "); buf.push_str(strukt.name().unwrap().text().as_str()); if let Some(type_params) = type_params { let lifetime_params = type_params .lifetime_params() .filter_map(|it| it.lifetime_token()) .map(|it| it.text().clone()); let type_params = type_params.type_params().filter_map(|it| it.name()).map(|it| it.text().clone()); format_to!(buf, "<{}>", lifetime_params.chain(type_params).sep_by(", ")) } format_to!(buf, " {{\n{}\n}}\n", code); buf } // Uses a syntax-driven approach to find any impl blocks for the struct that // exist within the module/file // // Returns `None` if we've found an existing `new` fn // // FIXME: change the new fn checking to a more semantic approach when that's more // viable (e.g. we process proc macros, etc) fn find_struct_impl(ctx: &AssistContext, strukt: &ast::StructDef) -> Option> { let db = ctx.db(); let module = strukt.syntax().ancestors().find(|node| { ast::Module::can_cast(node.kind()) || ast::SourceFile::can_cast(node.kind()) })?; let struct_def = ctx.sema.to_def(strukt)?; let block = module.descendants().filter_map(ast::ImplDef::cast).find_map(|impl_blk| { let blk = ctx.sema.to_def(&impl_blk)?; // FIXME: handle e.g. `struct S; impl S {}` // (we currently use the wrong type parameter) // also we wouldn't want to use e.g. `impl S` let same_ty = match blk.target_ty(db).as_adt() { Some(def) => def == Adt::Struct(struct_def), None => false, }; let not_trait_impl = blk.target_trait(db).is_none(); if !(same_ty && not_trait_impl) { None } else { Some(impl_blk) } }); if let Some(ref impl_blk) = block { if has_new_fn(impl_blk) { return None; } } Some(block) } fn has_new_fn(imp: &ast::ImplDef) -> bool { if let Some(il) = imp.item_list() { for item in il.assoc_items() { if let ast::AssocItem::FnDef(f) = item { if let Some(name) = f.name() { if name.text().eq_ignore_ascii_case("new") { return true; } } } } } false } #[cfg(test)] mod tests { use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target}; use super::*; #[test] #[rustfmt::skip] fn test_add_new() { // Check output of generation check_assist( add_new, "struct Foo {<|>}", "struct Foo {} impl Foo { fn $0new() -> Self { Self { } } } ", ); check_assist( add_new, "struct Foo {<|>}", "struct Foo {} impl Foo { fn $0new() -> Self { Self { } } } ", ); check_assist( add_new, "struct Foo<'a, T: Foo<'a>> {<|>}", "struct Foo<'a, T: Foo<'a>> {} impl<'a, T: Foo<'a>> Foo<'a, T> { fn $0new() -> Self { Self { } } } ", ); check_assist( add_new, "struct Foo { baz: String <|>}", "struct Foo { baz: String } impl Foo { fn $0new(baz: String) -> Self { Self { baz } } } ", ); check_assist( add_new, "struct Foo { baz: String, qux: Vec <|>}", "struct Foo { baz: String, qux: Vec } impl Foo { fn $0new(baz: String, qux: Vec) -> Self { Self { baz, qux } } } ", ); // Check that visibility modifiers don't get brought in for fields check_assist( add_new, "struct Foo { pub baz: String, pub qux: Vec <|>}", "struct Foo { pub baz: String, pub qux: Vec } impl Foo { fn $0new(baz: String, qux: Vec) -> Self { Self { baz, qux } } } ", ); // Check that it reuses existing impls check_assist( add_new, "struct Foo {<|>} impl Foo {} ", "struct Foo {} impl Foo { fn $0new() -> Self { Self { } } } ", ); check_assist( add_new, "struct Foo {<|>} impl Foo { fn qux(&self) {} } ", "struct Foo {} impl Foo { fn $0new() -> Self { Self { } } fn qux(&self) {} } ", ); check_assist( add_new, "struct Foo {<|>} impl Foo { fn qux(&self) {} fn baz() -> i32 { 5 } } ", "struct Foo {} impl Foo { fn $0new() -> Self { Self { } } fn qux(&self) {} fn baz() -> i32 { 5 } } ", ); // Check visibility of new fn based on struct check_assist( add_new, "pub struct Foo {<|>}", "pub struct Foo {} impl Foo { pub fn $0new() -> Self { Self { } } } ", ); check_assist( add_new, "pub(crate) struct Foo {<|>}", "pub(crate) struct Foo {} impl Foo { pub(crate) fn $0new() -> Self { Self { } } } ", ); } #[test] fn add_new_not_applicable_if_fn_exists() { check_assist_not_applicable( add_new, " struct Foo {<|>} impl Foo { fn new() -> Self { Self } }", ); check_assist_not_applicable( add_new, " struct Foo {<|>} impl Foo { fn New() -> Self { Self } }", ); } #[test] fn add_new_target() { check_assist_target( add_new, " struct SomeThingIrrelevant; /// Has a lifetime parameter struct Foo<'a, T: Foo<'a>> {<|>} struct EvenMoreIrrelevant; ", "/// Has a lifetime parameter struct Foo<'a, T: Foo<'a>> {}", ); } #[test] fn test_unrelated_new() { check_assist( add_new, r##" pub struct AstId { file_id: HirFileId, file_ast_id: FileAstId, } impl AstId { pub fn new(file_id: HirFileId, file_ast_id: FileAstId) -> AstId { AstId { file_id, file_ast_id } } } pub struct Source { pub file_id: HirFileId,<|> pub ast: T, } impl Source { pub fn map U, U>(self, f: F) -> Source { Source { file_id: self.file_id, ast: f(self.ast) } } } "##, r##" pub struct AstId { file_id: HirFileId, file_ast_id: FileAstId, } impl AstId { pub fn new(file_id: HirFileId, file_ast_id: FileAstId) -> AstId { AstId { file_id, file_ast_id } } } pub struct Source { pub file_id: HirFileId, pub ast: T, } impl Source { pub fn $0new(file_id: HirFileId, ast: T) -> Self { Self { file_id, ast } } pub fn map U, U>(self, f: F) -> Source { Source { file_id: self.file_id, ast: f(self.ast) } } } "##, ); } }