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|
use hir::HirDisplay;
use syntax::{
ast::{self, AstNode, LetStmt, NameOwner},
TextRange,
};
use crate::{AssistContext, AssistId, AssistKind, Assists};
// Assist: add_explicit_type
//
// Specify type for a let binding.
//
// ```
// fn main() {
// let x<|> = 92;
// }
// ```
// ->
// ```
// fn main() {
// let x: i32 = 92;
// }
// ```
pub(crate) fn add_explicit_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
let let_stmt = ctx.find_node_at_offset::<LetStmt>()?;
let module = ctx.sema.scope(let_stmt.syntax()).module()?;
let expr = let_stmt.initializer()?;
// Must be a binding
let pat = match let_stmt.pat()? {
ast::Pat::IdentPat(bind_pat) => bind_pat,
_ => return None,
};
let pat_range = pat.syntax().text_range();
// The binding must have a name
let name = pat.name()?;
let name_range = name.syntax().text_range();
let stmt_range = let_stmt.syntax().text_range();
let eq_range = let_stmt.eq_token()?.text_range();
// Assist should only be applicable if cursor is between 'let' and '='
let let_range = TextRange::new(stmt_range.start(), eq_range.start());
let cursor_in_range = let_range.contains_range(ctx.frange.range);
if !cursor_in_range {
return None;
}
// Assist not applicable if the type has already been specified
// and it has no placeholders
let ascribed_ty = let_stmt.ty();
if let Some(ty) = &ascribed_ty {
if ty.syntax().descendants().find_map(ast::InferType::cast).is_none() {
return None;
}
}
// Infer type
let ty = ctx.sema.type_of_expr(&expr)?;
if ty.contains_unknown() || ty.is_closure() {
return None;
}
let inferred_type = ty.display_source_code(ctx.db(), module.into()).ok()?;
acc.add(
AssistId("add_explicit_type", AssistKind::RefactorRewrite),
format!("Insert explicit type `{}`", inferred_type),
pat_range,
|builder| match ascribed_ty {
Some(ascribed_ty) => {
builder.replace(ascribed_ty.syntax().text_range(), inferred_type);
}
None => {
builder.insert(name_range.end(), format!(": {}", inferred_type));
}
},
)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
#[test]
fn add_explicit_type_target() {
check_assist_target(add_explicit_type, "fn f() { let a<|> = 1; }", "a");
}
#[test]
fn add_explicit_type_works_for_simple_expr() {
check_assist(add_explicit_type, "fn f() { let a<|> = 1; }", "fn f() { let a: i32 = 1; }");
}
#[test]
fn add_explicit_type_works_for_underscore() {
check_assist(
add_explicit_type,
"fn f() { let a<|>: _ = 1; }",
"fn f() { let a: i32 = 1; }",
);
}
#[test]
fn add_explicit_type_works_for_nested_underscore() {
check_assist(
add_explicit_type,
r#"
enum Option<T> {
Some(T),
None
}
fn f() {
let a<|>: Option<_> = Option::Some(1);
}"#,
r#"
enum Option<T> {
Some(T),
None
}
fn f() {
let a: Option<i32> = Option::Some(1);
}"#,
);
}
#[test]
fn add_explicit_type_works_for_macro_call() {
check_assist(
add_explicit_type,
r"macro_rules! v { () => {0u64} } fn f() { let a<|> = v!(); }",
r"macro_rules! v { () => {0u64} } fn f() { let a: u64 = v!(); }",
);
}
#[test]
fn add_explicit_type_works_for_macro_call_recursive() {
check_assist(
add_explicit_type,
r#"macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|> = v!(); }"#,
r#"macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a: u64 = v!(); }"#,
);
}
#[test]
fn add_explicit_type_not_applicable_if_ty_not_inferred() {
check_assist_not_applicable(add_explicit_type, "fn f() { let a<|> = None; }");
}
#[test]
fn add_explicit_type_not_applicable_if_ty_already_specified() {
check_assist_not_applicable(add_explicit_type, "fn f() { let a<|>: i32 = 1; }");
}
#[test]
fn add_explicit_type_not_applicable_if_specified_ty_is_tuple() {
check_assist_not_applicable(add_explicit_type, "fn f() { let a<|>: (i32, i32) = (3, 4); }");
}
#[test]
fn add_explicit_type_not_applicable_if_cursor_after_equals() {
check_assist_not_applicable(
add_explicit_type,
"fn f() {let a =<|> match 1 {2 => 3, 3 => 5};}",
)
}
#[test]
fn add_explicit_type_not_applicable_if_cursor_before_let() {
check_assist_not_applicable(
add_explicit_type,
"fn f() <|>{let a = match 1 {2 => 3, 3 => 5};}",
)
}
#[test]
fn closure_parameters_are_not_added() {
check_assist_not_applicable(
add_explicit_type,
r#"
fn main() {
let multiply_by_two<|> = |i| i * 3;
let six = multiply_by_two(2);
}"#,
)
}
#[test]
fn default_generics_should_not_be_added() {
check_assist(
add_explicit_type,
r#"
struct Test<K, T = u8> {
k: K,
t: T,
}
fn main() {
let test<|> = Test { t: 23u8, k: 33 };
}"#,
r#"
struct Test<K, T = u8> {
k: K,
t: T,
}
fn main() {
let test: Test<i32> = Test { t: 23u8, k: 33 };
}"#,
);
}
}
|
