1 files changed, 227 insertions, 0 deletions

diff --git a/crates/ide_assists/src/handlers/reorder_fields.rs b/crates/ide_assists/src/handlers/reorder_fields.rs
new file mode 100644
index 000000000..fba7d6ddb
--- /dev/null
+++ b/crates/ide_assists/src/handlers/reorder_fields.rs
@@ -0,0 +1,227 @@
+use itertools::Itertools;
+use rustc_hash::FxHashMap;
+
+use hir::{Adt, ModuleDef, PathResolution, Semantics, Struct};
+use ide_db::RootDatabase;
+use syntax::{algo, ast, match_ast, AstNode, SyntaxKind, SyntaxKind::*, SyntaxNode};
+use test_utils::mark;
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: reorder_fields
+//
+// Reorder the fields of record literals and record patterns in the same order as in
+// the definition.
+//
+// ```
+// struct Foo {foo: i32, bar: i32};
+// const test: Foo = $0Foo {bar: 0, foo: 1}
+// ```
+// ->
+// ```
+// struct Foo {foo: i32, bar: i32};
+// const test: Foo = Foo {foo: 1, bar: 0}
+// ```
+//
+pub(crate) fn reorder_fields(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    reorder::<ast::RecordExpr>(acc, ctx).or_else(|| reorder::<ast::RecordPat>(acc, ctx))
+}
+
+fn reorder<R: AstNode>(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let record = ctx.find_node_at_offset::<R>()?;
+    let path = record.syntax().children().find_map(ast::Path::cast)?;
+
+    let ranks = compute_fields_ranks(&path, &ctx)?;
+
+    let fields = get_fields(&record.syntax());
+    let sorted_fields = sorted_by_rank(&fields, |node| {
+        *ranks.get(&get_field_name(node)).unwrap_or(&usize::max_value())
+    });
+
+    if sorted_fields == fields {
+        mark::hit!(reorder_sorted_fields);
+        return None;
+    }
+
+    let target = record.syntax().text_range();
+    acc.add(
+        AssistId("reorder_fields", AssistKind::RefactorRewrite),
+        "Reorder record fields",
+        target,
+        |edit| {
+            let mut rewriter = algo::SyntaxRewriter::default();
+            for (old, new) in fields.iter().zip(&sorted_fields) {
+                rewriter.replace(old, new);
+            }
+            edit.rewrite(rewriter);
+        },
+    )
+}
+
+fn get_fields_kind(node: &SyntaxNode) -> Vec<SyntaxKind> {
+    match node.kind() {
+        RECORD_EXPR => vec![RECORD_EXPR_FIELD],
+        RECORD_PAT => vec![RECORD_PAT_FIELD, IDENT_PAT],
+        _ => vec![],
+    }
+}
+
+fn get_field_name(node: &SyntaxNode) -> String {
+    let res = match_ast! {
+        match node {
+            ast::RecordExprField(field) => field.field_name().map(|it| it.to_string()),
+            ast::RecordPatField(field) => field.field_name().map(|it| it.to_string()),
+            _ => None,
+        }
+    };
+    res.unwrap_or_default()
+}
+
+fn get_fields(record: &SyntaxNode) -> Vec<SyntaxNode> {
+    let kinds = get_fields_kind(record);
+    record.children().flat_map(|n| n.children()).filter(|n| kinds.contains(&n.kind())).collect()
+}
+
+fn sorted_by_rank(
+    fields: &[SyntaxNode],
+    get_rank: impl Fn(&SyntaxNode) -> usize,
+) -> Vec<SyntaxNode> {
+    fields.iter().cloned().sorted_by_key(get_rank).collect()
+}
+
+fn struct_definition(path: &ast::Path, sema: &Semantics<RootDatabase>) -> Option<Struct> {
+    match sema.resolve_path(path) {
+        Some(PathResolution::Def(ModuleDef::Adt(Adt::Struct(s)))) => Some(s),
+        _ => None,
+    }
+}
+
+fn compute_fields_ranks(path: &ast::Path, ctx: &AssistContext) -> Option<FxHashMap<String, usize>> {
+    Some(
+        struct_definition(path, &ctx.sema)?
+            .fields(ctx.db())
+            .iter()
+            .enumerate()
+            .map(|(idx, field)| (field.name(ctx.db()).to_string(), idx))
+            .collect(),
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::mark;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn reorder_sorted_fields() {
+        mark::check!(reorder_sorted_fields);
+        check_assist_not_applicable(
+            reorder_fields,
+            r#"
+struct Foo {
+    foo: i32,
+    bar: i32,
+}
+
+const test: Foo = $0Foo { foo: 0, bar: 0 };
+"#,
+        )
+    }
+
+    #[test]
+    fn trivial_empty_fields() {
+        check_assist_not_applicable(
+            reorder_fields,
+            r#"
+struct Foo {};
+const test: Foo = $0Foo {}
+"#,
+        )
+    }
+
+    #[test]
+    fn reorder_struct_fields() {
+        check_assist(
+            reorder_fields,
+            r#"
+struct Foo {foo: i32, bar: i32};
+const test: Foo = $0Foo {bar: 0, foo: 1}
+"#,
+            r#"
+struct Foo {foo: i32, bar: i32};
+const test: Foo = Foo {foo: 1, bar: 0}
+"#,
+        )
+    }
+
+    #[test]
+    fn reorder_struct_pattern() {
+        check_assist(
+            reorder_fields,
+            r#"
+struct Foo { foo: i64, bar: i64, baz: i64 }
+
+fn f(f: Foo) -> {
+    match f {
+        $0Foo { baz: 0, ref mut bar, .. } => (),
+        _ => ()
+    }
+}
+"#,
+            r#"
+struct Foo { foo: i64, bar: i64, baz: i64 }
+
+fn f(f: Foo) -> {
+    match f {
+        Foo { ref mut bar, baz: 0, .. } => (),
+        _ => ()
+    }
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn reorder_with_extra_field() {
+        check_assist(
+            reorder_fields,
+            r#"
+struct Foo {
+    foo: String,
+    bar: String,
+}
+
+impl Foo {
+    fn new() -> Foo {
+        let foo = String::new();
+        $0Foo {
+            bar: foo.clone(),
+            extra: "Extra field",
+            foo,
+        }
+    }
+}
+"#,
+            r#"
+struct Foo {
+    foo: String,
+    bar: String,
+}
+
+impl Foo {
+    fn new() -> Foo {
+        let foo = String::new();
+        Foo {
+            foo,
+            bar: foo.clone(),
+            extra: "Extra field",
+        }
+    }
+}
+"#,
+        )
+    }
+}