rust/crates/ra_assists/src/handlers/add_derive.rs
2020-02-07 17:28:02 +01:00

121 lines
2.9 KiB
Rust

use ra_syntax::{
ast::{self, AstNode, AttrsOwner},
SyntaxKind::{COMMENT, WHITESPACE},
TextUnit,
};
use crate::{Assist, AssistCtx, AssistId};
// Assist: add_derive
//
// Adds a new `#[derive()]` clause to a struct or enum.
//
// ```
// struct Point {
// x: u32,
// y: u32,<|>
// }
// ```
// ->
// ```
// #[derive()]
// struct Point {
// x: u32,
// y: u32,
// }
// ```
pub(crate) fn add_derive(ctx: AssistCtx) -> Option<Assist> {
let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
let node_start = derive_insertion_offset(&nominal)?;
ctx.add_assist(AssistId("add_derive"), "Add `#[derive]`", |edit| {
let derive_attr = nominal
.attrs()
.filter_map(|x| x.as_simple_call())
.filter(|(name, _arg)| name == "derive")
.map(|(_name, arg)| arg)
.next();
let offset = match derive_attr {
None => {
edit.insert(node_start, "#[derive()]\n");
node_start + TextUnit::of_str("#[derive(")
}
Some(tt) => tt.syntax().text_range().end() - TextUnit::of_char(')'),
};
edit.target(nominal.syntax().text_range());
edit.set_cursor(offset)
})
}
// Insert `derive` after doc comments.
fn derive_insertion_offset(nominal: &ast::NominalDef) -> Option<TextUnit> {
let non_ws_child = nominal
.syntax()
.children_with_tokens()
.find(|it| it.kind() != COMMENT && it.kind() != WHITESPACE)?;
Some(non_ws_child.text_range().start())
}
#[cfg(test)]
mod tests {
use super::*;
use crate::helpers::{check_assist, check_assist_target};
#[test]
fn add_derive_new() {
check_assist(
add_derive,
"struct Foo { a: i32, <|>}",
"#[derive(<|>)]\nstruct Foo { a: i32, }",
);
check_assist(
add_derive,
"struct Foo { <|> a: i32, }",
"#[derive(<|>)]\nstruct Foo { a: i32, }",
);
}
#[test]
fn add_derive_existing() {
check_assist(
add_derive,
"#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
"#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
);
}
#[test]
fn add_derive_new_with_doc_comment() {
check_assist(
add_derive,
"
/// `Foo` is a pretty important struct.
/// It does stuff.
struct Foo { a: i32<|>, }
",
"
/// `Foo` is a pretty important struct.
/// It does stuff.
#[derive(<|>)]
struct Foo { a: i32, }
",
);
}
#[test]
fn add_derive_target() {
check_assist_target(
add_derive,
"
struct SomeThingIrrelevant;
/// `Foo` is a pretty important struct.
/// It does stuff.
struct Foo { a: i32<|>, }
struct EvenMoreIrrelevant;
",
"/// `Foo` is a pretty important struct.
/// It does stuff.
struct Foo { a: i32, }",
);
}
}