From 91e482b46d43a24cd0a48ea1119b93105140cff2 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Fri, 27 Mar 2020 12:12:17 +0100
Subject: Replace if with if-let
---
crates/ra_assists/src/doc_tests/generated.rs | 26 +++++
.../src/handlers/replace_let_with_if_let.rs | 108 +++++++++++++++++++++
crates/ra_assists/src/lib.rs | 2 +
3 files changed, 136 insertions(+)
create mode 100644 crates/ra_assists/src/handlers/replace_let_with_if_let.rs
(limited to 'crates/ra_assists/src')
diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
index 62dcb3808..c0486a8a9 100644
--- a/crates/ra_assists/src/doc_tests/generated.rs
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -607,6 +607,32 @@ fn handle(action: Action) {
)
}
+#[test]
+fn doctest_replace_let_with_if_let() {
+ check(
+ "replace_let_with_if_let",
+ r#####"
+enum Option<T> { Some(T), None }
+
+fn main(action: Action) {
+ <|>let x = compute();
+}
+
+fn compute() -> Option<i32> { None }
+"#####,
+ r#####"
+enum Option<T> { Some(T), None }
+
+fn main(action: Action) {
+ if let Some(x) = compute() {
+ }
+}
+
+fn compute() -> Option<i32> { None }
+"#####,
+ )
+}
+
#[test]
fn doctest_replace_qualified_name_with_use() {
check(
diff --git a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
new file mode 100644
index 000000000..10e41f97e
--- /dev/null
+++ b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
@@ -0,0 +1,108 @@
+use hir::Adt;
+use ra_syntax::{
+ ast::{self, make},
+ AstNode, T,
+};
+
+use crate::{
+ assist_ctx::{Assist, AssistCtx},
+ AssistId,
+};
+use ast::edit::{AstNodeEdit, IndentLevel};
+use std::iter::once;
+
+// Assist: replace_let_with_if_let
+//
+// Replaces `if let` with an else branch with a `match` expression.
+//
+// ```
+// # enum Option<T> { Some(T), None }
+//
+// fn main(action: Action) {
+// <|>let x = compute();
+// }
+//
+// fn compute() -> Option<i32> { None }
+// ```
+// ->
+// ```
+// # enum Option<T> { Some(T), None }
+//
+// fn main(action: Action) {
+// if let Some(x) = compute() {
+// }
+// }
+//
+// fn compute() -> Option<i32> { None }
+// ```
+pub(crate) fn replace_let_with_if_let(ctx: AssistCtx) -> Option<Assist> {
+ let let_kw = ctx.find_token_at_offset(T![let])?;
+ let let_stmt = let_kw.ancestors().find_map(ast::LetStmt::cast)?;
+ let init = let_stmt.initializer()?;
+ let original_pat = let_stmt.pat()?;
+ let ty = ctx.sema.type_of_expr(&init)?;
+ let enum_ = match ty.as_adt() {
+ Some(Adt::Enum(it)) => it,
+ _ => return None,
+ };
+ let happy_case =
+ [("Result", "Ok"), ("Option", "Some")].iter().find_map(|(known_type, happy_case)| {
+ if &enum_.name(ctx.db).to_string() == known_type {
+ return Some(happy_case);
+ }
+ None
+ });
+
+ ctx.add_assist(AssistId("replace_let_with_if_let"), "Replace with if-let", |edit| {
+ let with_placeholder: ast::Pat = match happy_case {
+ None => make::placeholder_pat().into(),
+ Some(var_name) => make::tuple_struct_pat(
+ make::path_unqualified(make::path_segment(make::name_ref(var_name))),
+ once(make::placeholder_pat().into()),
+ )
+ .into(),
+ };
+ let block =
+ IndentLevel::from_node(let_stmt.syntax()).increase_indent(make::block_expr(None, None));
+ let if_ = make::expr_if(make::condition(init, Some(with_placeholder)), block);
+ let stmt = make::expr_stmt(if_);
+
+ let placeholder = stmt.syntax().descendants().find_map(ast::PlaceholderPat::cast).unwrap();
+ let target_offset =
+ let_stmt.syntax().text_range().start() + placeholder.syntax().text_range().start();
+ let stmt = stmt.replace_descendant(placeholder.into(), original_pat);
+
+ edit.replace_ast(ast::Stmt::from(let_stmt), ast::Stmt::from(stmt));
+ edit.target(let_kw.text_range());
+ edit.set_cursor(target_offset);
+ })
+}
+
+#[cfg(test)]
+mod tests {
+ use crate::helpers::check_assist;
+
+ use super::*;
+
+ #[test]
+ fn replace_let_unknown_enum() {
+ check_assist(
+ replace_let_with_if_let,
+ r"
+enum E<T> { X(T), Y(T) }
+
+fn main() {
+ <|>let x = E::X(92);
+}
+ ",
+ r"
+enum E<T> { X(T), Y(T) }
+
+fn main() {
+ if let <|>x = E::X(92) {
+ }
+}
+ ",
+ )
+ }
+}
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index bcc9b3f10..67a58fc1f 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -118,6 +118,7 @@ mod handlers {
mod remove_dbg;
mod remove_mut;
mod replace_if_let_with_match;
+ mod replace_let_with_if_let;
mod replace_qualified_name_with_use;
mod split_import;
@@ -153,6 +154,7 @@ mod handlers {
remove_dbg::remove_dbg,
remove_mut::remove_mut,
replace_if_let_with_match::replace_if_let_with_match,
+ replace_let_with_if_let::replace_let_with_if_let,
replace_qualified_name_with_use::replace_qualified_name_with_use,
split_import::split_import,
]
--
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