Merge remote-tracking branch 'upstream/master' into 503-hover-doc-links

1 files changed, 208 insertions, 0 deletions

diff --git a/crates/assists/src/handlers/add_custom_impl.rs b/crates/assists/src/handlers/add_custom_impl.rs
new file mode 100644
index 000000000..8757fa33f
--- /dev/null
+++ b/crates/assists/src/handlers/add_custom_impl.rs
@@ -0,0 +1,208 @@
+use itertools::Itertools;
+use syntax::{
+    ast::{self, AstNode},
+    Direction, SmolStr,
+    SyntaxKind::{IDENT, WHITESPACE},
+    TextRange, TextSize,
+};
+
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId, AssistKind,
+};
+
+// Assist: add_custom_impl
+//
+// Adds impl block for derived trait.
+//
+// ```
+// #[derive(Deb<|>ug, Display)]
+// struct S;
+// ```
+// ->
+// ```
+// #[derive(Display)]
+// struct S;
+//
+// impl Debug for S {
+//     $0
+// }
+// ```
+pub(crate) fn add_custom_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let attr = ctx.find_node_at_offset::<ast::Attr>()?;
+    let input = attr.token_tree()?;
+
+    let attr_name = attr
+        .syntax()
+        .descendants_with_tokens()
+        .filter(|t| t.kind() == IDENT)
+        .find_map(|i| i.into_token())
+        .filter(|t| *t.text() == "derive")?
+        .text()
+        .clone();
+
+    let trait_token =
+        ctx.token_at_offset().find(|t| t.kind() == IDENT && *t.text() != attr_name)?;
+
+    let annotated = attr.syntax().siblings(Direction::Next).find_map(ast::Name::cast)?;
+    let annotated_name = annotated.syntax().text().to_string();
+    let start_offset = annotated.syntax().parent()?.text_range().end();
+
+    let label =
+        format!("Add custom impl `{}` for `{}`", trait_token.text().as_str(), annotated_name);
+
+    let target = attr.syntax().text_range();
+    acc.add(AssistId("add_custom_impl", AssistKind::Refactor), label, target, |builder| {
+        let new_attr_input = input
+            .syntax()
+            .descendants_with_tokens()
+            .filter(|t| t.kind() == IDENT)
+            .filter_map(|t| t.into_token().map(|t| t.text().clone()))
+            .filter(|t| t != trait_token.text())
+            .collect::<Vec<SmolStr>>();
+        let has_more_derives = !new_attr_input.is_empty();
+
+        if has_more_derives {
+            let new_attr_input = format!("({})", new_attr_input.iter().format(", "));
+            builder.replace(input.syntax().text_range(), new_attr_input);
+        } else {
+            let attr_range = attr.syntax().text_range();
+            builder.delete(attr_range);
+
+            let line_break_range = attr
+                .syntax()
+                .next_sibling_or_token()
+                .filter(|t| t.kind() == WHITESPACE)
+                .map(|t| t.text_range())
+                .unwrap_or_else(|| TextRange::new(TextSize::from(0), TextSize::from(0)));
+            builder.delete(line_break_range);
+        }
+
+        match ctx.config.snippet_cap {
+            Some(cap) => {
+                builder.insert_snippet(
+                    cap,
+                    start_offset,
+                    format!("\n\nimpl {} for {} {{\n    $0\n}}", trait_token, annotated_name),
+                );
+            }
+            None => {
+                builder.insert(
+                    start_offset,
+                    format!("\n\nimpl {} for {} {{\n\n}}", trait_token, annotated_name),
+                );
+            }
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn add_custom_impl_for_unique_input() {
+        check_assist(
+            add_custom_impl,
+            "
+#[derive(Debu<|>g)]
+struct Foo {
+    bar: String,
+}
+            ",
+            "
+struct Foo {
+    bar: String,
+}
+
+impl Debug for Foo {
+    $0
+}
+            ",
+        )
+    }
+
+    #[test]
+    fn add_custom_impl_for_with_visibility_modifier() {
+        check_assist(
+            add_custom_impl,
+            "
+#[derive(Debug<|>)]
+pub struct Foo {
+    bar: String,
+}
+            ",
+            "
+pub struct Foo {
+    bar: String,
+}
+
+impl Debug for Foo {
+    $0
+}
+            ",
+        )
+    }
+
+    #[test]
+    fn add_custom_impl_when_multiple_inputs() {
+        check_assist(
+            add_custom_impl,
+            "
+#[derive(Display, Debug<|>, Serialize)]
+struct Foo {}
+            ",
+            "
+#[derive(Display, Serialize)]
+struct Foo {}
+
+impl Debug for Foo {
+    $0
+}
+            ",
+        )
+    }
+
+    #[test]
+    fn test_ignore_derive_macro_without_input() {
+        check_assist_not_applicable(
+            add_custom_impl,
+            "
+#[derive(<|>)]
+struct Foo {}
+            ",
+        )
+    }
+
+    #[test]
+    fn test_ignore_if_cursor_on_param() {
+        check_assist_not_applicable(
+            add_custom_impl,
+            "
+#[derive<|>(Debug)]
+struct Foo {}
+            ",
+        );
+
+        check_assist_not_applicable(
+            add_custom_impl,
+            "
+#[derive(Debug)<|>]
+struct Foo {}
+            ",
+        )
+    }
+
+    #[test]
+    fn test_ignore_if_not_derive() {
+        check_assist_not_applicable(
+            add_custom_impl,
+            "
+#[allow(non_camel_<|>case_types)]
+struct Foo {}
+            ",
+        )
+    }
+}