add replace_is_some_with_if_let_some assist

crates/ide-assists/src/handlers/replace_is_some_with_if_let_some.rs

@@ -0,0 +1,90 @@
+use syntax::ast::{self, AstNode};
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: replace_is_some_with_if_let
+//
+// Replace `if x.is_some()` with `if let Some(_tmp) = x`.
+//
+// ```
+// fn main() {
+//     let x = Some(1);
+//     if x.is_som$0e() {}
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let x = Some(1);
+//     if let Some(_tmp) = x {}
+// }
+// ```
+pub(crate) fn replace_is_some_with_if_let_some(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+) -> Option<()> {
+    let if_expr = ctx.find_node_at_offset::<ast::IfExpr>()?;
+
+    let cond = if_expr.condition()?;
+    let call_expr = match cond {
+        ast::Expr::MethodCallExpr(call) => call,
+        _ => return None,
+    };
+
+    let name_ref = call_expr.name_ref()?;
+    if name_ref.text() != "is_some" {
+        return None;
+    }
+
+    let receiver = call_expr.receiver()?;
+    let target = call_expr.syntax().text_range();
+
+    acc.add(
+        AssistId("replace_is_some_with_if_let_some", AssistKind::RefactorRewrite),
+        "Replace `is_some` with `if let Some`",
+        target,
+        |edit| {
+            let replacement = format!("let Some(_tmp) = {}", receiver);
+            edit.replace(target, replacement);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::replace_is_some_with_if_let_some;
+
+    #[test]
+    fn replace_is_some_with_if_let_works() {
+        check_assist(
+            replace_is_some_with_if_let_some,
+            r#"
+fn main() {
+    let x = Some(1);
+    if x.is_som$0e() {}
+}
+"#,
+            r#"
+fn main() {
+    let x = Some(1);
+    if let Some(_tmp) = x {}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn replace_is_some_with_if_let_not_applicable() {
+        check_assist_not_applicable(
+            replace_is_some_with_if_let_some,
+            r#"
+fn main() {
+    let x = Some(1);
+    if x.is_non$0e() {}
+}
+"#,
+        );
+    }
+}

crates/ide-assists/src/lib.rs

@@ -213,6 +213,7 @@ mod handlers {
     mod unwrap_block;
     mod unwrap_result_return_type;
     mod unqualify_method_call;
+    mod replace_is_some_with_if_let_some;
     mod wrap_return_type_in_result;
     mod into_to_qualified_from;
 
@@ -332,6 +333,7 @@ pub(crate) fn all() -> &'static [Handler] {
             unwrap_result_return_type::unwrap_result_return_type,
             unwrap_tuple::unwrap_tuple,
             unqualify_method_call::unqualify_method_call,
+            replace_is_some_with_if_let_some::replace_is_some_with_if_let_some,
             wrap_return_type_in_result::wrap_return_type_in_result,
             // These are manually sorted for better priorities. By default,
             // priority is determined by the size of the target range (smaller