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|
use hir::HirDisplay;
use ra_syntax::{
ast::{self, AstNode, LetStmt, NameOwner, TypeAscriptionOwner},
TextRange,
};
use crate::{Assist, AssistCtx, AssistId};
// 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(ctx: AssistCtx) -> Option<Assist> {
let stmt = ctx.find_node_at_offset::<LetStmt>()?;
let expr = stmt.initializer()?;
let pat = stmt.pat()?;
// Must be a binding
let pat = match pat {
ast::Pat::BindPat(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 = stmt.syntax().text_range();
let eq_range = stmt.eq_token()?.text_range();
// Assist should only be applicable if cursor is between 'let' and '='
let let_range = TextRange::from_to(stmt_range.start(), eq_range.start());
let cursor_in_range = ctx.frange.range.is_subrange(&let_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 = stmt.ascribed_type();
if let Some(ref ty) = ascribed_ty {
if ty.syntax().descendants().find_map(ast::PlaceholderType::cast).is_none() {
return None;
}
}
// Infer type
let ty = ctx.sema.type_of_expr(&expr)?;
// Assist not applicable if the type is unknown
if ty.contains_unknown() {
return None;
}
let db = ctx.db;
ctx.add_assist(
AssistId("add_explicit_type"),
format!("Insert explicit type '{}'", ty.display(db)),
|edit| {
edit.target(pat_range);
if let Some(ascribed_ty) = ascribed_ty {
edit.replace(ascribed_ty.syntax().text_range(), format!("{}", ty.display(db)));
} else {
edit.insert(name_range.end(), format!(": {}", ty.display(db)));
}
},
)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::helpers::{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,
"macro_rules! v { () => {0u64} } fn f() { let a<|> = v!(); }",
"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,
"macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|> = v!(); }",
"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};}",
)
}
}
|
