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|
use syntax::{
ast::{Expr, GenericArg},
ast::{LetStmt, Type::InferType},
AstNode, TextRange,
};
use crate::{
assist_context::{AssistContext, Assists},
AssistId, AssistKind,
};
// Assist: replace_turbofish_with_explicit_type
//
// Converts `::<_>` to an explicit type assignment.
//
// ```
// fn make<T>() -> T { ) }
// fn main() {
// let a = make$0::<i32>();
// }
// ```
// ->
// ```
// fn make<T>() -> T { ) }
// fn main() {
// let a: i32 = make();
// }
// ```
pub(crate) fn replace_turbofish_with_explicit_type(
acc: &mut Assists,
ctx: &AssistContext<'_>,
) -> Option<()> {
let let_stmt = ctx.find_node_at_offset::<LetStmt>()?;
let initializer = let_stmt.initializer()?;
let generic_args = match &initializer {
Expr::MethodCallExpr(ce) => ce.generic_arg_list()?,
Expr::CallExpr(ce) => {
if let Expr::PathExpr(pe) = ce.expr()? {
pe.path()?.segment()?.generic_arg_list()?
} else {
cov_mark::hit!(not_applicable_if_non_path_function_call);
return None;
}
}
_ => {
cov_mark::hit!(not_applicable_if_non_function_call_initializer);
return None;
}
};
// Find range of ::<_>
let colon2 = generic_args.coloncolon_token()?;
let r_angle = generic_args.r_angle_token()?;
let turbofish_range = TextRange::new(colon2.text_range().start(), r_angle.text_range().end());
let turbofish_args: Vec<GenericArg> = generic_args.generic_args().into_iter().collect();
// Find type of ::<_>
if turbofish_args.len() != 1 {
cov_mark::hit!(not_applicable_if_not_single_arg);
return None;
}
// An improvement would be to check that this is correctly part of the return value of the
// function call, or sub in the actual return type.
let turbofish_type = &turbofish_args[0];
let initializer_start = initializer.syntax().text_range().start();
if ctx.offset() > turbofish_range.end() || ctx.offset() < initializer_start {
cov_mark::hit!(not_applicable_outside_turbofish);
return None;
}
if let None = let_stmt.colon_token() {
// If there's no colon in a let statement, then there is no explicit type.
// let x = fn::<...>();
let ident_range = let_stmt.pat()?.syntax().text_range();
return acc.add(
AssistId("replace_turbofish_with_explicit_type", AssistKind::RefactorRewrite),
"Replace turbofish with explicit type",
TextRange::new(initializer_start, turbofish_range.end()),
|builder| {
builder.insert(ident_range.end(), format!(": {}", turbofish_type));
builder.delete(turbofish_range);
},
);
} else if let Some(InferType(t)) = let_stmt.ty() {
// If there's a type inferrence underscore, we can offer to replace it with the type in
// the turbofish.
// let x: _ = fn::<...>();
let underscore_range = t.syntax().text_range();
return acc.add(
AssistId("replace_turbofish_with_explicit_type", AssistKind::RefactorRewrite),
"Replace `_` with turbofish type",
turbofish_range,
|builder| {
builder.replace(underscore_range, turbofish_type.to_string());
builder.delete(turbofish_range);
},
);
}
None
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
#[test]
fn replaces_turbofish_for_vec_string() {
check_assist(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a = make$0::<Vec<String>>();
}
"#,
r#"
fn make<T>() -> T {}
fn main() {
let a: Vec<String> = make();
}
"#,
);
}
#[test]
fn replaces_method_calls() {
// foo.make() is a method call which uses a different expr in the let initializer
check_assist(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a = foo.make$0::<Vec<String>>();
}
"#,
r#"
fn make<T>() -> T {}
fn main() {
let a: Vec<String> = foo.make();
}
"#,
);
}
#[test]
fn replace_turbofish_target() {
check_assist_target(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a = $0make::<Vec<String>>();
}
"#,
r#"make::<Vec<String>>"#,
);
}
#[test]
fn not_applicable_outside_turbofish() {
cov_mark::check!(not_applicable_outside_turbofish);
check_assist_not_applicable(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let $0a = make::<Vec<String>>();
}
"#,
);
}
#[test]
fn replace_inferred_type_placeholder() {
check_assist(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a: _ = make$0::<Vec<String>>();
}
"#,
r#"
fn make<T>() -> T {}
fn main() {
let a: Vec<String> = make();
}
"#,
);
}
#[test]
fn not_applicable_constant_initializer() {
cov_mark::check!(not_applicable_if_non_function_call_initializer);
check_assist_not_applicable(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a = "foo"$0;
}
"#,
);
}
#[test]
fn not_applicable_non_path_function_call() {
cov_mark::check!(not_applicable_if_non_path_function_call);
check_assist_not_applicable(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
$0let a = (|| {})();
}
"#,
);
}
#[test]
fn non_applicable_multiple_generic_args() {
cov_mark::check!(not_applicable_if_not_single_arg);
check_assist_not_applicable(
replace_turbofish_with_explicit_type,
r#"
fn make<T>() -> T {}
fn main() {
let a = make$0::<Vec<String>, i32>();
}
"#,
);
}
}
|
