From 4f0d02c27694f52dce637e1bfbf2a0bd28dadeac Mon Sep 17 00:00:00 2001 From: Lukas Wirth Date: Fri, 6 Nov 2020 21:49:03 +0100 Subject: Enable infer_function_return_type in return-type position --- .../src/handlers/infer_function_return_type.rs | 158 +++++++++++++++++---- 1 file changed, 129 insertions(+), 29 deletions(-) (limited to 'crates/assists/src/handlers') diff --git a/crates/assists/src/handlers/infer_function_return_type.rs b/crates/assists/src/handlers/infer_function_return_type.rs index b4944a6b0..80864c530 100644 --- a/crates/assists/src/handlers/infer_function_return_type.rs +++ b/crates/assists/src/handlers/infer_function_return_type.rs @@ -1,5 +1,5 @@ use hir::HirDisplay; -use syntax::{ast, AstNode, SyntaxToken, TextSize}; +use syntax::{ast, AstNode, TextRange, TextSize}; use test_utils::mark; use crate::{AssistContext, AssistId, AssistKind, Assists}; @@ -7,7 +7,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists}; // Assist: infer_function_return_type // // Adds the return type to a function or closure inferred from its tail expression if it doesn't have a return -// type specified. +// type specified. This assists is useable in a functions or closures tail expression or return type position. // // ``` // fn foo() { 4<|>2i32 } @@ -17,10 +17,12 @@ use crate::{AssistContext, AssistId, AssistKind, Assists}; // fn foo() -> i32 { 42i32 } // ``` pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> { - let expr = ctx.find_node_at_offset::()?; - let (tail_expr, insert_pos, wrap_expr) = extract_tail(expr)?; + let (tail_expr, builder_edit_pos, wrap_expr) = extract_tail(ctx)?; let module = ctx.sema.scope(tail_expr.syntax()).module()?; - let ty = ctx.sema.type_of_expr(&tail_expr).filter(|ty| !ty.is_unit())?; + let ty = ctx.sema.type_of_expr(&tail_expr)?; + if ty.is_unit() { + return None; + } let ty = ty.display_source_code(ctx.db(), module.into()).ok()?; acc.add( @@ -28,8 +30,14 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext) "Add this function's return type", tail_expr.syntax().text_range(), |builder| { - let insert_pos = insert_pos.text_range().end() + TextSize::from(1); - builder.insert(insert_pos, &format!("-> {} ", ty)); + match builder_edit_pos { + InsertOrReplace::Insert(insert_pos) => { + builder.insert(insert_pos, &format!("-> {} ", ty)) + } + InsertOrReplace::Replace(text_range) => { + builder.replace(text_range, &format!("-> {}", ty)) + } + } if wrap_expr { mark::hit!(wrap_closure_non_block_expr); // `|x| x` becomes `|x| -> T x` which is invalid, so wrap it in a block @@ -39,34 +47,69 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext) ) } -fn extract_tail(expr: ast::Expr) -> Option<(ast::Expr, SyntaxToken, bool)> { - let (ret_ty, tail_expr, insert_pos, wrap_expr) = - if let Some(closure) = expr.syntax().ancestors().find_map(ast::ClosureExpr::cast) { - let (tail_expr, wrap_expr) = match closure.body()? { +enum InsertOrReplace { + Insert(TextSize), + Replace(TextRange), +} + +/// Check the potentially already specified return type and reject it or turn it into a builder command +/// if allowed. +fn ret_ty_to_action(ret_ty: Option, insert_pos: TextSize) -> Option { + match ret_ty { + Some(ret_ty) => match ret_ty.ty() { + Some(ast::Type::InferType(_)) | None => { + mark::hit!(existing_infer_ret_type); + mark::hit!(existing_infer_ret_type_closure); + Some(InsertOrReplace::Replace(ret_ty.syntax().text_range())) + } + _ => { + mark::hit!(existing_ret_type); + mark::hit!(existing_ret_type_closure); + None + } + }, + None => Some(InsertOrReplace::Insert(insert_pos + TextSize::from(1))), + } +} + +fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool)> { + let (tail_expr, return_type_range, action, wrap_expr) = + if let Some(closure) = ctx.find_node_at_offset::() { + let rpipe_pos = closure.param_list()?.syntax().last_token()?.text_range().end(); + let action = ret_ty_to_action(closure.ret_type(), rpipe_pos)?; + + let body = closure.body()?; + let body_start = body.syntax().first_token()?.text_range().start(); + let (tail_expr, wrap_expr) = match body { ast::Expr::BlockExpr(block) => (block.expr()?, false), body => (body, true), }; - let ret_ty = closure.ret_type(); - let rpipe = closure.param_list()?.syntax().last_token()?; - (ret_ty, tail_expr, rpipe, wrap_expr) + + let ret_range = TextRange::new(rpipe_pos, body_start); + (tail_expr, ret_range, action, wrap_expr) } else { - let func = expr.syntax().ancestors().find_map(ast::Fn::cast)?; - let tail_expr = func.body()?.expr()?; - let ret_ty = func.ret_type(); - let rparen = func.param_list()?.r_paren_token()?; - (ret_ty, tail_expr, rparen, false) + let func = ctx.find_node_at_offset::()?; + let rparen_pos = func.param_list()?.r_paren_token()?.text_range().end(); + let action = ret_ty_to_action(func.ret_type(), rparen_pos)?; + + let body = func.body()?; + let tail_expr = body.expr()?; + + let ret_range_end = body.l_curly_token()?.text_range().start(); + let ret_range = TextRange::new(rparen_pos, ret_range_end); + (tail_expr, ret_range, action, false) }; - if ret_ty.is_some() { - mark::hit!(existing_ret_type); - mark::hit!(existing_ret_type_closure); - return None; - } - // check whether the expr we were at is indeed the tail expression - if !tail_expr.syntax().text_range().contains_range(expr.syntax().text_range()) { - mark::hit!(not_tail_expr); + let frange = ctx.frange.range; + if return_type_range.contains_range(frange) { + mark::hit!(cursor_in_ret_position); + mark::hit!(cursor_in_ret_position_closure); + } else if tail_expr.syntax().text_range().contains_range(frange) { + mark::hit!(cursor_on_tail); + mark::hit!(cursor_on_tail_closure); + } else { return None; } - Some((tail_expr, insert_pos, wrap_expr)) + Some((tail_expr, action, wrap_expr)) } #[cfg(test)] @@ -75,8 +118,65 @@ mod tests { use super::*; + #[test] + fn infer_return_type_specified_inferred() { + mark::check!(existing_infer_ret_type); + check_assist( + infer_function_return_type, + r#"fn foo() -> <|>_ { + 45 + }"#, + r#"fn foo() -> i32 { + 45 + }"#, + ); + } + + #[test] + fn infer_return_type_specified_inferred_closure() { + mark::check!(existing_infer_ret_type_closure); + check_assist( + infer_function_return_type, + r#"fn foo() { + || -> _ {<|>45}; + }"#, + r#"fn foo() { + || -> i32 {45}; + }"#, + ); + } + + #[test] + fn infer_return_type_cursor_at_return_type_pos() { + mark::check!(cursor_in_ret_position); + check_assist( + infer_function_return_type, + r#"fn foo() <|>{ + 45 + }"#, + r#"fn foo() -> i32 { + 45 + }"#, + ); + } + + #[test] + fn infer_return_type_cursor_at_return_type_pos_closure() { + mark::check!(cursor_in_ret_position_closure); + check_assist( + infer_function_return_type, + r#"fn foo() { + || <|>45 + }"#, + r#"fn foo() { + || -> i32 {45} + }"#, + ); + } + #[test] fn infer_return_type() { + mark::check!(cursor_on_tail); check_assist( infer_function_return_type, r#"fn foo() { @@ -122,7 +222,6 @@ mod tests { #[test] fn not_applicable_non_tail_expr() { - mark::check!(not_tail_expr); check_assist_not_applicable( infer_function_return_type, r#"fn foo() { @@ -144,6 +243,7 @@ mod tests { #[test] fn infer_return_type_closure_block() { + mark::check!(cursor_on_tail_closure); check_assist( infer_function_return_type, r#"fn foo() { -- cgit v1.2.3