diff --git a/crates/ra_assists/src/assists/add_new.rs b/crates/ra_assists/src/assists/add_new.rs new file mode 100644 index 0000000000..a8839cfba3 --- /dev/null +++ b/crates/ra_assists/src/assists/add_new.rs @@ -0,0 +1,379 @@ +use format_buf::format; +use hir::{db::HirDatabase, FromSource}; +use join_to_string::join; +use ra_syntax::{ + ast::{ + self, AstNode, NameOwner, StructKind, TypeAscriptionOwner, TypeParamsOwner, VisibilityOwner, + }, + TextUnit, T, +}; +use std::fmt::Write; + +use crate::{Assist, AssistCtx, AssistId}; + +// Assist: add_new +// +// Adds a new inherent impl for a type. +// +// ``` +// struct Ctx { +// data: T,<|> +// } +// ``` +// -> +// ``` +// struct Ctx { +// data: T, +// } +// +// impl Ctx { +// fn new(data: T) -> Self { Self { data } } +// } +// +// ``` +pub(crate) fn add_new(ctx: AssistCtx) -> 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(), strukt.is_union()) { + (StructKind::Named(named), false) => named, + _ => return None, + }; + + // Return early if we've found an existing new fn + let impl_block = find_struct_impl(&ctx, &strukt)?; + + ctx.add_assist(AssistId("add_new"), "add new fn", |edit| { + edit.target(strukt.syntax().text_range()); + + let mut buf = String::with_capacity(512); + + if impl_block.is_some() { + buf.push('\n'); + } + + let vis = strukt.visibility().map(|v| format!("{} ", v.syntax())); + let vis = vis.as_ref().map(String::as_str).unwrap_or(""); + write!(&mut buf, " {}fn new(", vis).unwrap(); + + join(field_list.fields().map(|f| { + format!( + "{}: {}", + f.name().unwrap().syntax().text(), + f.ascribed_type().unwrap().syntax().text() + ) + })) + .separator(", ") + .to_buf(&mut buf); + + buf.push_str(") -> Self { Self {"); + + join(field_list.fields().map(|f| f.name().unwrap().syntax().text())) + .separator(", ") + .surround_with(" ", " ") + .to_buf(&mut buf); + + buf.push_str("} }"); + + let (start_offset, end_offset) = if let Some(impl_block) = impl_block { + buf.push('\n'); + let start = impl_block + .syntax() + .descendants_with_tokens() + .find(|t| t.kind() == T!['{']) + .unwrap() + .text_range() + .end(); + + (start, TextUnit::from_usize(1)) + } else { + buf = generate_impl_text(&strukt, &buf); + let start = strukt.syntax().text_range().end(); + + (start, TextUnit::from_usize(3)) + }; + + edit.set_cursor(start_offset + TextUnit::of_str(&buf) - end_offset); + edit.insert(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!(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()); + join(lifetime_params.chain(type_params)).surround_with("<", ">").to_buf(&mut buf); + } + + format!(&mut 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: &AssistCtx, + 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_ty = { + let src = hir::Source { file_id: ctx.frange.file_id.into(), ast: strukt.clone() }; + hir::Struct::from_source(db, src).unwrap().ty(db) + }; + + let mut found_new_fn = false; + + let block = module.descendants().filter_map(ast::ImplBlock::cast).find(|impl_blk| { + if found_new_fn { + return false; + } + + let src = hir::Source { file_id: ctx.frange.file_id.into(), ast: impl_blk.clone() }; + let blk = hir::ImplBlock::from_source(db, src).unwrap(); + + let same_ty = blk.target_ty(db) == struct_ty; + let not_trait_impl = blk.target_trait(db).is_none(); + + found_new_fn = has_new_fn(impl_blk); + + same_ty && not_trait_impl + }); + + if found_new_fn { + None + } else { + Some(block) + } +} + +fn has_new_fn(imp: &ast::ImplBlock) -> bool { + if let Some(il) = imp.item_list() { + for item in il.impl_items() { + if let ast::ImplItem::FnDef(f) = item { + if f.name().unwrap().text().eq_ignore_ascii_case("new") { + return true; + } + } + } + } + + false +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target}; + + #[test] + #[rustfmt::skip] + fn test_add_new() { + // Check output of generation + check_assist( + add_new, +"struct Foo {<|>}", +"struct Foo {} + +impl Foo { + fn new() -> Self { Self { } }<|> +} +", + ); + check_assist( + add_new, +"struct Foo {<|>}", +"struct Foo {} + +impl Foo { + fn new() -> 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 new() -> Self { Self { } }<|> +} +", + ); + check_assist( + add_new, +"struct Foo { baz: String <|>}", +"struct Foo { baz: String } + +impl Foo { + fn new(baz: String) -> Self { Self { baz } }<|> +} +", + ); + check_assist( + add_new, +"struct Foo { baz: String, qux: Vec <|>}", +"struct Foo { baz: String, qux: Vec } + +impl Foo { + fn new(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 new(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 new() -> Self { Self { } }<|> +} +", + ); + check_assist( + add_new, +"struct Foo {<|>} + +impl Foo { + fn qux(&self) {} +} +", +"struct Foo {} + +impl Foo { + fn new() -> 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 new() -> 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 new() -> Self { Self { } }<|> +} +", + ); + check_assist( + add_new, +"pub(crate) struct Foo {<|>}", +"pub(crate) struct Foo {} + +impl Foo { + pub(crate) fn new() -> 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>> {}", + ); + } +} diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs index 1bee76f59a..176761efb9 100644 --- a/crates/ra_assists/src/doc_tests/generated.rs +++ b/crates/ra_assists/src/doc_tests/generated.rs @@ -156,6 +156,28 @@ fn process(map: HashMap) {} ) } +#[test] +fn doctest_add_new() { + check( + "add_new", + r#####" +struct Ctx { + data: T,<|> +} +"#####, + r#####" +struct Ctx { + data: T, +} + +impl Ctx { + fn new(data: T) -> Self { Self { data } } +} + +"#####, + ) +} + #[test] fn doctest_apply_demorgan() { check( diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs index 39c1c283f4..f2f0dacbf7 100644 --- a/crates/ra_assists/src/lib.rs +++ b/crates/ra_assists/src/lib.rs @@ -95,6 +95,7 @@ mod assists { mod add_derive; mod add_explicit_type; mod add_impl; + mod add_new; mod apply_demorgan; mod flip_comma; mod flip_binexpr; @@ -119,6 +120,7 @@ mod assists { add_derive::add_derive, add_explicit_type::add_explicit_type, add_impl::add_impl, + add_new::add_new, apply_demorgan::apply_demorgan, change_visibility::change_visibility, fill_match_arms::fill_match_arms, diff --git a/docs/user/assists.md b/docs/user/assists.md index 303353e742..8da7578e2f 100644 --- a/docs/user/assists.md +++ b/docs/user/assists.md @@ -150,6 +150,27 @@ use std::collections::HashMap; fn process(map: HashMap) {} ``` +## `add_new` + +Adds a new inherent impl for a type. + +```rust +// BEFORE +struct Ctx { + data: T,┃ +} + +// AFTER +struct Ctx { + data: T, +} + +impl Ctx { + fn new(data: T) -> Self { Self { data } } +} + +``` + ## `apply_demorgan` Apply [De Morgan's law](https://en.wikipedia.org/wiki/De_Morgan%27s_laws).