use hir::HirDisplay; use ide_db::{base_db::FileId, helpers::SnippetCap}; use rustc_hash::{FxHashMap, FxHashSet}; use stdx::to_lower_snake_case; use syntax::{ ast::{ self, edit::{AstNodeEdit, IndentLevel}, make, ArgListOwner, AstNode, ModuleItemOwner, }, SyntaxKind, SyntaxNode, TextSize, }; use crate::{ utils::{render_snippet, Cursor}, AssistContext, AssistId, AssistKind, Assists, }; // Assist: generate_function // // Adds a stub function with a signature matching the function under the cursor. // // ``` // struct Baz; // fn baz() -> Baz { Baz } // fn foo() { // bar$0("", baz()); // } // // ``` // -> // ``` // struct Baz; // fn baz() -> Baz { Baz } // fn foo() { // bar("", baz()); // } // // fn bar(arg: &str, baz: Baz) ${0:-> ()} { // todo!() // } // // ``` pub(crate) fn generate_function(acc: &mut Assists, ctx: &AssistContext) -> Option<()> { let path_expr: ast::PathExpr = ctx.find_node_at_offset()?; let call = path_expr.syntax().parent().and_then(ast::CallExpr::cast)?; let path = path_expr.path()?; if ctx.sema.resolve_path(&path).is_some() { // The function call already resolves, no need to add a function return None; } let target_module = match path.qualifier() { Some(qualifier) => match ctx.sema.resolve_path(&qualifier) { Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))) => Some(module), _ => return None, }, None => None, }; let function_builder = FunctionBuilder::from_call(&ctx, &call, &path, target_module)?; let target = call.syntax().text_range(); acc.add( AssistId("generate_function", AssistKind::Generate), format!("Generate `{}` function", function_builder.fn_name), target, |builder| { let function_template = function_builder.render(); builder.edit_file(function_template.file); let new_fn = function_template.to_string(ctx.config.snippet_cap); match ctx.config.snippet_cap { Some(cap) => builder.insert_snippet(cap, function_template.insert_offset, new_fn), None => builder.insert(function_template.insert_offset, new_fn), } }, ) } struct FunctionTemplate { insert_offset: TextSize, leading_ws: String, fn_def: ast::Fn, ret_type: ast::RetType, should_render_snippet: bool, trailing_ws: String, file: FileId, } impl FunctionTemplate { fn to_string(&self, cap: Option<SnippetCap>) -> String { let f = match (cap, self.should_render_snippet) { (Some(cap), true) => { render_snippet(cap, self.fn_def.syntax(), Cursor::Replace(self.ret_type.syntax())) } _ => self.fn_def.to_string(), }; format!("{}{}{}", self.leading_ws, f, self.trailing_ws) } } struct FunctionBuilder { target: GeneratedFunctionTarget, fn_name: ast::Name, type_params: Option<ast::GenericParamList>, params: ast::ParamList, ret_type: ast::RetType, should_render_snippet: bool, file: FileId, needs_pub: bool, } impl FunctionBuilder { /// Prepares a generated function that matches `call`. /// The function is generated in `target_module` or next to `call` fn from_call( ctx: &AssistContext, call: &ast::CallExpr, path: &ast::Path, target_module: Option<hir::Module>, ) -> Option<Self> { let mut file = ctx.frange.file_id; let target = match &target_module { Some(target_module) => { let module_source = target_module.definition_source(ctx.db()); let (in_file, target) = next_space_for_fn_in_module(ctx.sema.db, &module_source)?; file = in_file; target } None => next_space_for_fn_after_call_site(&call)?, }; let needs_pub = target_module.is_some(); let target_module = target_module.or_else(|| ctx.sema.scope(target.syntax()).module())?; let fn_name = fn_name(&path)?; let (type_params, params) = fn_args(ctx, target_module, &call)?; // should_render_snippet intends to express a rough level of confidence about // the correctness of the return type. // // If we are able to infer some return type, and that return type is not unit, we // don't want to render the snippet. The assumption here is in this situation the // return type is just as likely to be correct as any other part of the generated // function. // // In the case where the return type is inferred as unit it is likely that the // user does in fact intend for this generated function to return some non unit // type, but that the current state of their code doesn't allow that return type // to be accurately inferred. let (ret_ty, should_render_snippet) = { match ctx.sema.type_of_expr(&ast::Expr::CallExpr(call.clone())) { Some(ty) if ty.is_unknown() || ty.is_unit() => (make::ty_unit(), true), Some(ty) => { let rendered = ty.display_source_code(ctx.db(), target_module.into()); match rendered { Ok(rendered) => (make::ty(&rendered), false), Err(_) => (make::ty_unit(), true), } } None => (make::ty_unit(), true), } }; let ret_type = make::ret_type(ret_ty); Some(Self { target, fn_name, type_params, params, ret_type, should_render_snippet, file, needs_pub, }) } fn render(self) -> FunctionTemplate { let placeholder_expr = make::ext::expr_todo(); let fn_body = make::block_expr(vec![], Some(placeholder_expr)); let visibility = if self.needs_pub { Some(make::visibility_pub_crate()) } else { None }; let mut fn_def = make::fn_( visibility, self.fn_name, self.type_params, self.params, fn_body, Some(self.ret_type), ); let leading_ws; let trailing_ws; let insert_offset = match self.target { GeneratedFunctionTarget::BehindItem(it) => { let indent = IndentLevel::from_node(&it); leading_ws = format!("\n\n{}", indent); fn_def = fn_def.indent(indent); trailing_ws = String::new(); it.text_range().end() } GeneratedFunctionTarget::InEmptyItemList(it) => { let indent = IndentLevel::from_node(&it); leading_ws = format!("\n{}", indent + 1); fn_def = fn_def.indent(indent + 1); trailing_ws = format!("\n{}", indent); it.text_range().start() + TextSize::of('{') } }; FunctionTemplate { insert_offset, leading_ws, ret_type: fn_def.ret_type().unwrap(), should_render_snippet: self.should_render_snippet, fn_def, trailing_ws, file: self.file, } } } enum GeneratedFunctionTarget { BehindItem(SyntaxNode), InEmptyItemList(SyntaxNode), } impl GeneratedFunctionTarget { fn syntax(&self) -> &SyntaxNode { match self { GeneratedFunctionTarget::BehindItem(it) => it, GeneratedFunctionTarget::InEmptyItemList(it) => it, } } } fn fn_name(call: &ast::Path) -> Option<ast::Name> { let name = call.segment()?.syntax().to_string(); Some(make::name(&name)) } /// Computes the type variables and arguments required for the generated function fn fn_args( ctx: &AssistContext, target_module: hir::Module, call: &ast::CallExpr, ) -> Option<(Option<ast::GenericParamList>, ast::ParamList)> { let mut arg_names = Vec::new(); let mut arg_types = Vec::new(); for arg in call.arg_list()?.args() { arg_names.push(match fn_arg_name(&arg) { Some(name) => name, None => String::from("arg"), }); arg_types.push(match fn_arg_type(ctx, target_module, &arg) { Some(ty) => ty, None => String::from("()"), }); } deduplicate_arg_names(&mut arg_names); let params = arg_names .into_iter() .zip(arg_types) .map(|(name, ty)| make::param(make::ident_pat(make::name(&name)).into(), make::ty(&ty))); Some((None, make::param_list(None, params))) } /// Makes duplicate argument names unique by appending incrementing numbers. /// /// ``` /// let mut names: Vec<String> = /// vec!["foo".into(), "foo".into(), "bar".into(), "baz".into(), "bar".into()]; /// deduplicate_arg_names(&mut names); /// let expected: Vec<String> = /// vec!["foo_1".into(), "foo_2".into(), "bar_1".into(), "baz".into(), "bar_2".into()]; /// assert_eq!(names, expected); /// ``` fn deduplicate_arg_names(arg_names: &mut Vec<String>) { let arg_name_counts = arg_names.iter().fold(FxHashMap::default(), |mut m, name| { *m.entry(name).or_insert(0) += 1; m }); let duplicate_arg_names: FxHashSet<String> = arg_name_counts .into_iter() .filter(|(_, count)| *count >= 2) .map(|(name, _)| name.clone()) .collect(); let mut counter_per_name = FxHashMap::default(); for arg_name in arg_names.iter_mut() { if duplicate_arg_names.contains(arg_name) { let counter = counter_per_name.entry(arg_name.clone()).or_insert(1); arg_name.push('_'); arg_name.push_str(&counter.to_string()); *counter += 1; } } } fn fn_arg_name(fn_arg: &ast::Expr) -> Option<String> { match fn_arg { ast::Expr::CastExpr(cast_expr) => fn_arg_name(&cast_expr.expr()?), _ => { let s = fn_arg .syntax() .descendants() .filter(|d| ast::NameRef::can_cast(d.kind())) .last()? .to_string(); Some(to_lower_snake_case(&s)) } } } fn fn_arg_type( ctx: &AssistContext, target_module: hir::Module, fn_arg: &ast::Expr, ) -> Option<String> { let ty = ctx.sema.type_of_expr(fn_arg)?; if ty.is_unknown() { return None; } if let Ok(rendered) = ty.display_source_code(ctx.db(), target_module.into()) { Some(rendered) } else { None } } /// Returns the position inside the current mod or file /// directly after the current block /// We want to write the generated function directly after /// fns, impls or macro calls, but inside mods fn next_space_for_fn_after_call_site(expr: &ast::CallExpr) -> Option<GeneratedFunctionTarget> { let mut ancestors = expr.syntax().ancestors().peekable(); let mut last_ancestor: Option<SyntaxNode> = None; while let Some(next_ancestor) = ancestors.next() { match next_ancestor.kind() { SyntaxKind::SOURCE_FILE => { break; } SyntaxKind::ITEM_LIST => { if ancestors.peek().map(|a| a.kind()) == Some(SyntaxKind::MODULE) { break; } } _ => {} } last_ancestor = Some(next_ancestor); } last_ancestor.map(GeneratedFunctionTarget::BehindItem) } fn next_space_for_fn_in_module( db: &dyn hir::db::AstDatabase, module_source: &hir::InFile<hir::ModuleSource>, ) -> Option<(FileId, GeneratedFunctionTarget)> { let file = module_source.file_id.original_file(db); let assist_item = match &module_source.value { hir::ModuleSource::SourceFile(it) => { if let Some(last_item) = it.items().last() { GeneratedFunctionTarget::BehindItem(last_item.syntax().clone()) } else { GeneratedFunctionTarget::BehindItem(it.syntax().clone()) } } hir::ModuleSource::Module(it) => { if let Some(last_item) = it.item_list().and_then(|it| it.items().last()) { GeneratedFunctionTarget::BehindItem(last_item.syntax().clone()) } else { GeneratedFunctionTarget::InEmptyItemList(it.item_list()?.syntax().clone()) } } hir::ModuleSource::BlockExpr(it) => { if let Some(last_item) = it.statements().take_while(|stmt| matches!(stmt, ast::Stmt::Item(_))).last() { GeneratedFunctionTarget::BehindItem(last_item.syntax().clone()) } else { GeneratedFunctionTarget::InEmptyItemList(it.syntax().clone()) } } }; Some((file, assist_item)) } #[cfg(test)] mod tests { use crate::tests::{check_assist, check_assist_not_applicable}; use super::*; #[test] fn add_function_with_no_args() { check_assist( generate_function, r" fn foo() { bar$0(); } ", r" fn foo() { bar(); } fn bar() ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_from_method() { // This ensures that the function is correctly generated // in the next outer mod or file check_assist( generate_function, r" impl Foo { fn foo() { bar$0(); } } ", r" impl Foo { fn foo() { bar(); } } fn bar() ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_directly_after_current_block() { // The new fn should not be created at the end of the file or module check_assist( generate_function, r" fn foo1() { bar$0(); } fn foo2() {} ", r" fn foo1() { bar(); } fn bar() ${0:-> ()} { todo!() } fn foo2() {} ", ) } #[test] fn add_function_with_no_args_in_same_module() { check_assist( generate_function, r" mod baz { fn foo() { bar$0(); } } ", r" mod baz { fn foo() { bar(); } fn bar() ${0:-> ()} { todo!() } } ", ) } #[test] fn add_function_with_upper_camel_case_arg() { check_assist( generate_function, r" struct BazBaz; fn foo() { bar$0(BazBaz); } ", r" struct BazBaz; fn foo() { bar(BazBaz); } fn bar(baz_baz: BazBaz) ${0:-> ()} { todo!() } ", ); } #[test] fn add_function_with_upper_camel_case_arg_as_cast() { check_assist( generate_function, r" struct BazBaz; fn foo() { bar$0(&BazBaz as *const BazBaz); } ", r" struct BazBaz; fn foo() { bar(&BazBaz as *const BazBaz); } fn bar(baz_baz: *const BazBaz) ${0:-> ()} { todo!() } ", ); } #[test] fn add_function_with_function_call_arg() { check_assist( generate_function, r" struct Baz; fn baz() -> Baz { todo!() } fn foo() { bar$0(baz()); } ", r" struct Baz; fn baz() -> Baz { todo!() } fn foo() { bar(baz()); } fn bar(baz: Baz) ${0:-> ()} { todo!() } ", ); } #[test] fn add_function_with_method_call_arg() { check_assist( generate_function, r" struct Baz; impl Baz { fn foo(&self) -> Baz { ba$0r(self.baz()) } fn baz(&self) -> Baz { Baz } } ", r" struct Baz; impl Baz { fn foo(&self) -> Baz { bar(self.baz()) } fn baz(&self) -> Baz { Baz } } fn bar(baz: Baz) -> Baz { todo!() } ", ) } #[test] fn add_function_with_string_literal_arg() { check_assist( generate_function, r#" fn foo() { $0bar("bar") } "#, r#" fn foo() { bar("bar") } fn bar(arg: &str) ${0:-> ()} { todo!() } "#, ) } #[test] fn add_function_with_char_literal_arg() { check_assist( generate_function, r#" fn foo() { $0bar('x') } "#, r#" fn foo() { bar('x') } fn bar(arg: char) ${0:-> ()} { todo!() } "#, ) } #[test] fn add_function_with_int_literal_arg() { check_assist( generate_function, r" fn foo() { $0bar(42) } ", r" fn foo() { bar(42) } fn bar(arg: i32) ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_with_cast_int_literal_arg() { check_assist( generate_function, r" fn foo() { $0bar(42 as u8) } ", r" fn foo() { bar(42 as u8) } fn bar(arg: u8) ${0:-> ()} { todo!() } ", ) } #[test] fn name_of_cast_variable_is_used() { // Ensures that the name of the cast type isn't used // in the generated function signature. check_assist( generate_function, r" fn foo() { let x = 42; bar$0(x as u8) } ", r" fn foo() { let x = 42; bar(x as u8) } fn bar(x: u8) ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_with_variable_arg() { check_assist( generate_function, r" fn foo() { let worble = (); $0bar(worble) } ", r" fn foo() { let worble = (); bar(worble) } fn bar(worble: ()) ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_with_impl_trait_arg() { check_assist( generate_function, r" trait Foo {} fn foo() -> impl Foo { todo!() } fn baz() { $0bar(foo()) } ", r" trait Foo {} fn foo() -> impl Foo { todo!() } fn baz() { bar(foo()) } fn bar(foo: impl Foo) ${0:-> ()} { todo!() } ", ) } #[test] fn borrowed_arg() { check_assist( generate_function, r" struct Baz; fn baz() -> Baz { todo!() } fn foo() { bar$0(&baz()) } ", r" struct Baz; fn baz() -> Baz { todo!() } fn foo() { bar(&baz()) } fn bar(baz: &Baz) ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_with_qualified_path_arg() { check_assist( generate_function, r" mod Baz { pub struct Bof; pub fn baz() -> Bof { Bof } } fn foo() { $0bar(Baz::baz()) } ", r" mod Baz { pub struct Bof; pub fn baz() -> Bof { Bof } } fn foo() { bar(Baz::baz()) } fn bar(baz: Baz::Bof) ${0:-> ()} { todo!() } ", ) } #[test] #[ignore] // FIXME fix printing the generics of a `Ty` to make this test pass fn add_function_with_generic_arg() { check_assist( generate_function, r" fn foo<T>(t: T) { $0bar(t) } ", r" fn foo<T>(t: T) { bar(t) } fn bar<T>(t: T) ${0:-> ()} { todo!() } ", ) } #[test] #[ignore] // FIXME Fix function type printing to make this test pass fn add_function_with_fn_arg() { check_assist( generate_function, r" struct Baz; impl Baz { fn new() -> Self { Baz } } fn foo() { $0bar(Baz::new); } ", r" struct Baz; impl Baz { fn new() -> Self { Baz } } fn foo() { bar(Baz::new); } fn bar(arg: fn() -> Baz) ${0:-> ()} { todo!() } ", ) } #[test] #[ignore] // FIXME Fix closure type printing to make this test pass fn add_function_with_closure_arg() { check_assist( generate_function, r" fn foo() { let closure = |x: i64| x - 1; $0bar(closure) } ", r" fn foo() { let closure = |x: i64| x - 1; bar(closure) } fn bar(closure: impl Fn(i64) -> i64) ${0:-> ()} { todo!() } ", ) } #[test] fn unresolveable_types_default_to_unit() { check_assist( generate_function, r" fn foo() { $0bar(baz) } ", r" fn foo() { bar(baz) } fn bar(baz: ()) ${0:-> ()} { todo!() } ", ) } #[test] fn arg_names_dont_overlap() { check_assist( generate_function, r" struct Baz; fn baz() -> Baz { Baz } fn foo() { $0bar(baz(), baz()) } ", r" struct Baz; fn baz() -> Baz { Baz } fn foo() { bar(baz(), baz()) } fn bar(baz_1: Baz, baz_2: Baz) ${0:-> ()} { todo!() } ", ) } #[test] fn arg_name_counters_start_at_1_per_name() { check_assist( generate_function, r#" struct Baz; fn baz() -> Baz { Baz } fn foo() { $0bar(baz(), baz(), "foo", "bar") } "#, r#" struct Baz; fn baz() -> Baz { Baz } fn foo() { bar(baz(), baz(), "foo", "bar") } fn bar(baz_1: Baz, baz_2: Baz, arg_1: &str, arg_2: &str) ${0:-> ()} { todo!() } "#, ) } #[test] fn add_function_in_module() { check_assist( generate_function, r" mod bar {} fn foo() { bar::my_fn$0() } ", r" mod bar { pub(crate) fn my_fn() ${0:-> ()} { todo!() } } fn foo() { bar::my_fn() } ", ) } #[test] #[ignore] // Ignored until local imports are supported. // See https://github.com/rust-analyzer/rust-analyzer/issues/1165 fn qualified_path_uses_correct_scope() { check_assist( generate_function, " mod foo { pub struct Foo; } fn bar() { use foo::Foo; let foo = Foo; baz$0(foo) } ", " mod foo { pub struct Foo; } fn bar() { use foo::Foo; let foo = Foo; baz(foo) } fn baz(foo: foo::Foo) ${0:-> ()} { todo!() } ", ) } #[test] fn add_function_in_module_containing_other_items() { check_assist( generate_function, r" mod bar { fn something_else() {} } fn foo() { bar::my_fn$0() } ", r" mod bar { fn something_else() {} pub(crate) fn my_fn() ${0:-> ()} { todo!() } } fn foo() { bar::my_fn() } ", ) } #[test] fn add_function_in_nested_module() { check_assist( generate_function, r" mod bar { mod baz {} } fn foo() { bar::baz::my_fn$0() } ", r" mod bar { mod baz { pub(crate) fn my_fn() ${0:-> ()} { todo!() } } } fn foo() { bar::baz::my_fn() } ", ) } #[test] fn add_function_in_another_file() { check_assist( generate_function, r" //- /main.rs mod foo; fn main() { foo::bar$0() } //- /foo.rs ", r" pub(crate) fn bar() ${0:-> ()} { todo!() }", ) } #[test] fn add_function_with_return_type() { check_assist( generate_function, r" fn main() { let x: u32 = foo$0(); } ", r" fn main() { let x: u32 = foo(); } fn foo() -> u32 { todo!() } ", ) } #[test] fn add_function_not_applicable_if_function_already_exists() { check_assist_not_applicable( generate_function, r" fn foo() { bar$0(); } fn bar() {} ", ) } #[test] fn add_function_not_applicable_if_unresolved_variable_in_call_is_selected() { check_assist_not_applicable( // bar is resolved, but baz isn't. // The assist is only active if the cursor is on an unresolved path, // but the assist should only be offered if the path is a function call. generate_function, r" fn foo() { bar(b$0az); } fn bar(baz: ()) {} ", ) } #[test] #[ignore] fn create_method_with_no_args() { check_assist( generate_function, r" struct Foo; impl Foo { fn foo(&self) { self.bar()$0; } } ", r" struct Foo; impl Foo { fn foo(&self) { self.bar(); } fn bar(&self) { todo!(); } } ", ) } }