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|
use std::fmt::Write;
use hir::{
AdtDef, Ty, FieldSource, source_binder,
db::HirDatabase,
};
use ra_syntax::ast::{self, AstNode};
use crate::{AssistCtx, Assist};
pub(crate) fn fill_match_arms(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
let match_expr = ctx.node_at_offset::<ast::MatchExpr>()?;
// We already have some match arms, so we don't provide any assists.
match match_expr.match_arm_list() {
Some(arm_list) if arm_list.arms().count() > 0 => {
return None;
}
_ => {}
}
let expr = match_expr.expr()?;
let function =
source_binder::function_from_child_node(ctx.db, ctx.frange.file_id, expr.syntax())?;
let infer_result = function.infer(ctx.db);
let syntax_mapping = function.body_syntax_mapping(ctx.db);
let node_expr = syntax_mapping.node_expr(expr)?;
let match_expr_ty = infer_result[node_expr].clone();
let enum_def = match match_expr_ty {
Ty::Adt { def_id: AdtDef::Enum(e), .. } => e,
_ => return None,
};
let enum_name = enum_def.name(ctx.db)?;
let db = ctx.db;
ctx.build("fill match arms", |edit| {
let mut buf = format!("match {} {{\n", expr.syntax().text().to_string());
let variants = enum_def.variants(db);
for variant in variants {
let name = match variant.name(db) {
Some(it) => it,
None => continue,
};
write!(&mut buf, " {}::{}", enum_name, name.to_string()).unwrap();
let pat = variant
.fields(db)
.into_iter()
.map(|field| {
let name = field.name(db).to_string();
let (_, source) = field.source(db);
match source {
FieldSource::Named(_) => name,
FieldSource::Pos(_) => "_".to_string(),
}
})
.collect::<Vec<_>>();
match pat.first().map(|s| s.as_str()) {
Some("_") => write!(&mut buf, "({})", pat.join(", ")).unwrap(),
Some(_) => write!(&mut buf, "{{{}}}", pat.join(", ")).unwrap(),
None => (),
};
buf.push_str(" => (),\n");
}
buf.push_str("}");
edit.set_cursor(expr.syntax().range().start());
edit.replace_node_and_indent(match_expr.syntax(), buf);
})
}
#[cfg(test)]
mod tests {
use crate::helpers::check_assist;
use super::fill_match_arms;
#[test]
fn fill_match_arms_empty_body() {
check_assist(
fill_match_arms,
r#"
enum A {
As,
Bs,
Cs(String),
Ds(String, String),
Es{x: usize, y: usize}
}
fn main() {
let a = A::As;
match a<|> {}
}
"#,
r#"
enum A {
As,
Bs,
Cs(String),
Ds(String, String),
Es{x: usize, y: usize}
}
fn main() {
let a = A::As;
match <|>a {
A::As => (),
A::Bs => (),
A::Cs(_) => (),
A::Ds(_, _) => (),
A::Es{x, y} => (),
}
}
"#,
);
}
#[test]
fn fill_match_arms_no_body() {
check_assist(
fill_match_arms,
r#"
enum E { X, Y}
fn main() {
match E::X<|>
}
"#,
r#"
enum E { X, Y}
fn main() {
match <|>E::X {
E::X => (),
E::Y => (),
}
}
"#,
);
}
}
|
