feat: add assist to convert char literal

Author: Young-Flash

src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_char_literal.rs

@@ -0,0 +1,46 @@
+use syntax::{AstToken, ast};
+
+use crate::{AssistContext, AssistId, Assists, GroupLabel};
+
+// Assist: convert_char_literal
+//
+// Converts character literals between different representations. Currently supports normal character -> ASCII / Unicode escape.
+pub(crate) fn convert_char_literal(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    if !ctx.has_empty_selection() {
+        return None;
+    }
+
+    let literal = ctx.find_node_at_offset::<ast::Literal>()?;
+    let literal = match literal.kind() {
+        ast::LiteralKind::Char(it) => it,
+        _ => return None,
+    };
+
+    let value = literal.value().ok()?;
+    let text = literal.syntax().text().to_string();
+    let range = literal.syntax().text_range();
+    let group_id = GroupLabel("Convert char representation".into());
+
+    let mut add_assist = |converted: String| {
+        // Skip no-op assists (e.g. `'const C: char = '\\x61';'` already matches the ASCII form).
+        if converted == text {
+            return;
+        }
+        let label = format!("Convert {text} to {converted}");
+        acc.add_group(
+            &group_id,
+            AssistId::refactor_rewrite("convert_char_literal"),
+            label,
+            range,
+            |builder| builder.replace(range, converted),
+        );
+    };
+
+    if value.is_ascii() {
+        add_assist(format!("'\\x{:02x}'", value as u32));
+    }
+
+    add_assist(format!("'\\u{{{:x}}}'", value as u32));
+
+    Some(())
+}

src/tools/rust-analyzer/crates/ide-assists/src/lib.rs

@@ -119,6 +119,7 @@ mod handlers {
     mod change_visibility;
     mod convert_bool_then;
     mod convert_bool_to_enum;
+    mod convert_char_literal;
     mod convert_closure_to_fn;
     mod convert_comment_block;
     mod convert_comment_from_or_to_doc;
@@ -256,6 +257,7 @@ mod handlers {
             convert_bool_then::convert_bool_then_to_if,
             convert_bool_then::convert_if_to_bool_then,
             convert_bool_to_enum::convert_bool_to_enum,
+            convert_char_literal::convert_char_literal,
             convert_closure_to_fn::convert_closure_to_fn,
             convert_comment_block::convert_comment_block,
             convert_comment_from_or_to_doc::convert_comment_from_or_to_doc,