139 lines
4.1 KiB
Rust
139 lines
4.1 KiB
Rust
use hir::db::HirDatabase;
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use ra_syntax::{
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ast::{self, edit, make, AstNode, NameOwner, TypeBoundsOwner},
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SyntaxElement,
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SyntaxKind::*,
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};
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use crate::{Assist, AssistCtx, AssistId};
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// Assist: move_bounds_to_where_clause
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//
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// Moves inline type bounds to a where clause.
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//
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// ```
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// fn apply<T, U, <|>F: FnOnce(T) -> U>(f: F, x: T) -> U {
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// f(x)
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// }
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// ```
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// ->
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// ```
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// fn apply<T, U, F>(f: F, x: T) -> U where F: FnOnce(T) -> U {
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// f(x)
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// }
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// ```
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pub(crate) fn move_bounds_to_where_clause(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
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let type_param_list = ctx.find_node_at_offset::<ast::TypeParamList>()?;
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let mut type_params = type_param_list.type_params();
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if type_params.all(|p| p.type_bound_list().is_none()) {
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return None;
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}
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let parent = type_param_list.syntax().parent()?;
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if parent.children_with_tokens().any(|it| it.kind() == WHERE_CLAUSE) {
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return None;
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}
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let anchor: SyntaxElement = match parent.kind() {
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FN_DEF => ast::FnDef::cast(parent)?.body()?.syntax().clone().into(),
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TRAIT_DEF => ast::TraitDef::cast(parent)?.item_list()?.syntax().clone().into(),
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IMPL_BLOCK => ast::ImplBlock::cast(parent)?.item_list()?.syntax().clone().into(),
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ENUM_DEF => ast::EnumDef::cast(parent)?.variant_list()?.syntax().clone().into(),
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STRUCT_DEF => parent
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.children_with_tokens()
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.find(|it| it.kind() == RECORD_FIELD_DEF_LIST || it.kind() == SEMI)?,
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_ => return None,
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};
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ctx.add_assist(AssistId("move_bounds_to_where_clause"), "Move to where clause", |edit| {
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let new_params = type_param_list
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.type_params()
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.filter(|it| it.type_bound_list().is_some())
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.map(|type_param| {
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let without_bounds = type_param.remove_bounds();
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(type_param, without_bounds)
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});
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let new_type_param_list = edit::replace_descendants(&type_param_list, new_params);
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edit.replace_ast(type_param_list.clone(), new_type_param_list);
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let where_clause = {
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let predicates = type_param_list.type_params().filter_map(build_predicate);
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make::where_clause(predicates)
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};
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let to_insert = match anchor.prev_sibling_or_token() {
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Some(ref elem) if elem.kind() == WHITESPACE => format!("{} ", where_clause.syntax()),
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_ => format!(" {}", where_clause.syntax()),
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};
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edit.insert(anchor.text_range().start(), to_insert);
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edit.target(type_param_list.syntax().text_range());
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})
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}
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fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
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let path = make::path_from_name_ref(make::name_ref(¶m.name()?.syntax().to_string()));
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let predicate = make::where_pred(path, param.type_bound_list()?.bounds());
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Some(predicate)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::helpers::check_assist;
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#[test]
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fn move_bounds_to_where_clause_fn() {
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check_assist(
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move_bounds_to_where_clause,
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r#"
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fn foo<T: u32, <|>F: FnOnce(T) -> T>() {}
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"#,
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r#"
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fn foo<T, <|>F>() where T: u32, F: FnOnce(T) -> T {}
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"#,
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);
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}
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#[test]
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fn move_bounds_to_where_clause_impl() {
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check_assist(
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move_bounds_to_where_clause,
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r#"
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impl<U: u32, <|>T> A<U, T> {}
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"#,
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r#"
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impl<U, <|>T> A<U, T> where U: u32 {}
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"#,
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);
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}
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#[test]
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fn move_bounds_to_where_clause_struct() {
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check_assist(
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move_bounds_to_where_clause,
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r#"
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struct A<<|>T: Iterator<Item = u32>> {}
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"#,
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r#"
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struct A<<|>T> where T: Iterator<Item = u32> {}
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"#,
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);
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}
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#[test]
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fn move_bounds_to_where_clause_tuple_struct() {
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check_assist(
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move_bounds_to_where_clause,
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r#"
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struct Pair<<|>T: u32>(T, T);
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"#,
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r#"
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struct Pair<<|>T>(T, T) where T: u32;
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"#,
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);
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}
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}
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