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|
use hir::{
HirDisplay, Ty,
db::HirDatabase,
};
use ra_syntax::{
SyntaxKind,
ast::{LetStmt, PatKind, NameOwner, AstNode}
};
use crate::{AssistCtx, Assist, AssistId};
/// Add explicit type assist.
pub(crate) fn add_explicit_type(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
let stmt = ctx.node_at_offset::<LetStmt>()?;
let expr = stmt.initializer()?;
let pat = stmt.pat()?;
// Must be a binding
let pat = match pat.kind() {
PatKind::BindPat(bind_pat) => bind_pat,
_ => return None,
};
let pat_range = pat.syntax().range();
// The binding must have a name
let name = pat.name()?;
let name_range = name.syntax().range();
// Assist not applicable if the type has already been specified
if stmt.syntax().children_with_tokens().any(|child| child.kind() == SyntaxKind::COLON) {
return None;
}
// Infer type
let db = ctx.db;
let analyzer = hir::SourceAnalyser::new(db, ctx.frange.file_id, stmt.syntax());
let ty = analyzer.type_of(db, expr)?;
// Assist not applicable if the type is unknown
if is_unknown(&ty) {
return None;
}
ctx.add_action(AssistId("add_explicit_type"), "add explicit type", |edit| {
edit.target(pat_range);
edit.insert(name_range.end(), format!(": {}", ty.display(db)));
});
ctx.build()
}
/// Returns true if any type parameter is unknown
fn is_unknown(ty: &Ty) -> bool {
match ty {
Ty::Unknown => true,
Ty::Apply(a_ty) => a_ty.parameters.iter().any(is_unknown),
_ => false,
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::helpers::{ check_assist, check_assist_target, check_assist_not_applicable };
#[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_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); }");
}
}
|
