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|
use syntax::{
ast::{self, edit::AstNodeEdit, make, AstNode, NameOwner, TypeBoundsOwner},
match_ast,
SyntaxKind::*,
T,
};
use crate::{AssistContext, AssistId, AssistKind, Assists};
// Assist: move_bounds_to_where_clause
//
// Moves inline type bounds to a where clause.
//
// ```
// fn apply<T, U, $0F: FnOnce(T) -> U>(f: F, x: T) -> U {
// f(x)
// }
// ```
// ->
// ```
// fn apply<T, U, F>(f: F, x: T) -> U where F: FnOnce(T) -> U {
// f(x)
// }
// ```
pub(crate) fn move_bounds_to_where_clause(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
let type_param_list = ctx.find_node_at_offset::<ast::GenericParamList>()?;
let mut type_params = type_param_list.type_params();
if type_params.all(|p| p.type_bound_list().is_none()) {
return None;
}
let parent = type_param_list.syntax().parent()?;
if parent.children_with_tokens().any(|it| it.kind() == WHERE_CLAUSE) {
return None;
}
let anchor = match_ast! {
match parent {
ast::Fn(it) => it.body()?.syntax().clone().into(),
ast::Trait(it) => it.assoc_item_list()?.syntax().clone().into(),
ast::Impl(it) => it.assoc_item_list()?.syntax().clone().into(),
ast::Enum(it) => it.variant_list()?.syntax().clone().into(),
ast::Struct(it) => {
it.syntax().children_with_tokens()
.find(|it| it.kind() == RECORD_FIELD_LIST || it.kind() == T![;])?
},
_ => return None
}
};
let target = type_param_list.syntax().text_range();
acc.add(
AssistId("move_bounds_to_where_clause", AssistKind::RefactorRewrite),
"Move to where clause",
target,
|edit| {
let new_params = type_param_list
.type_params()
.filter(|it| it.type_bound_list().is_some())
.map(|type_param| {
let without_bounds = type_param.remove_bounds();
(type_param, without_bounds)
});
let new_type_param_list = type_param_list.replace_descendants(new_params);
edit.replace_ast(type_param_list.clone(), new_type_param_list);
let where_clause = {
let predicates = type_param_list.type_params().filter_map(build_predicate);
make::where_clause(predicates)
};
let to_insert = match anchor.prev_sibling_or_token() {
Some(ref elem) if elem.kind() == WHITESPACE => {
format!("{} ", where_clause.syntax())
}
_ => format!(" {}", where_clause.syntax()),
};
edit.insert(anchor.text_range().start(), to_insert);
},
)
}
fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
let path = {
let name_ref = make::name_ref(¶m.name()?.syntax().to_string());
let segment = make::path_segment(name_ref);
make::path_unqualified(segment)
};
let predicate = make::where_pred(path, param.type_bound_list()?.bounds());
Some(predicate)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::check_assist;
#[test]
fn move_bounds_to_where_clause_fn() {
check_assist(
move_bounds_to_where_clause,
r#"
fn foo<T: u32, $0F: FnOnce(T) -> T>() {}
"#,
r#"
fn foo<T, F>() where T: u32, F: FnOnce(T) -> T {}
"#,
);
}
#[test]
fn move_bounds_to_where_clause_impl() {
check_assist(
move_bounds_to_where_clause,
r#"
impl<U: u32, $0T> A<U, T> {}
"#,
r#"
impl<U, T> A<U, T> where U: u32 {}
"#,
);
}
#[test]
fn move_bounds_to_where_clause_struct() {
check_assist(
move_bounds_to_where_clause,
r#"
struct A<$0T: Iterator<Item = u32>> {}
"#,
r#"
struct A<T> where T: Iterator<Item = u32> {}
"#,
);
}
#[test]
fn move_bounds_to_where_clause_tuple_struct() {
check_assist(
move_bounds_to_where_clause,
r#"
struct Pair<$0T: u32>(T, T);
"#,
r#"
struct Pair<T>(T, T) where T: u32;
"#,
);
}
}
|
