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|
use hir::{db::HirDatabase, HirDisplay};
use ra_syntax::{
ast::{self, AstNode, LetStmt, NameOwner},
T,
};
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<impl HirDatabase>) -> 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();
// Assist not applicable if the type has already been specified
if stmt.syntax().children_with_tokens().any(|child| child.kind() == T![:]) {
return None;
}
// Infer type
let db = ctx.db;
let analyzer = ctx.source_analyzer(stmt.syntax(), None);
let ty = analyzer.type_of(db, &expr)?;
// Assist not applicable if the type is unknown
if ty.contains_unknown() {
return None;
}
ctx.add_assist(AssistId("add_explicit_type"), "add explicit type", |edit| {
edit.target(pat_range);
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_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); }");
}
}
|
