reorder imports in group

Configurations.md

@@ -1007,7 +1007,42 @@ use lorem;
 use sit;
 ```
 
-See also [`reorder_imported_names`](#reorder_imported_names).
+See also [`reorder_imported_names`](#reorder_imported_names), [`reorder_imports_in_group`](#reorder_imports_in_group).
+
+## `reorder_imports_in_group`
+
+Reorder import statements in group
+
+- **Default value**: `false`
+- **Possible values**: `true`, `false`
+
+**Note:** This option takes effect only when [`reorder_imports`](#reorder_imports) is set to `true`.
+
+#### `false`:
+
+```rust
+use std::mem;
+use std::io;
+
+use lorem;
+use ipsum;
+use dolor;
+use sit;
+```
+
+#### `true`:
+
+```rust
+use std::io;
+use std::mem;
+
+use dolor;
+use ipsum;
+use lorem;
+use sit;
+```
+
+See also [`reorder_imports`](#reorder_imports).
 
 ## `single_line_if_else_max_width`
 

src/config.rs

@@ -387,6 +387,7 @@ create_config! {
     chain_indent: IndentStyle, IndentStyle::Block, "Indentation of chain";
     chain_one_line_max: usize, 60, "Maximum length of a chain to fit on a single line";
     reorder_imports: bool, false, "Reorder import statements alphabetically";
+    reorder_imports_in_group: bool, false, "Reorder import statements in group";
     reorder_imported_names: bool, false,
         "Reorder lists of names in import statements alphabetically";
     single_line_if_else_max_width: usize, 50, "Maximum line length for single line if-else \

src/visitor.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use std::cmp;
+
 use syntax::{ast, ptr, visit};
 use syntax::codemap::{self, CodeMap, Span, BytePos};
 use syntax::parse::ParseSess;
@@ -31,6 +33,19 @@ fn is_use_item(item: &ast::Item) -> bool {
     }
 }
 
+fn item_bound(item: &ast::Item) -> Span {
+    item.attrs
+        .iter()
+        .map(|attr| attr.span)
+        .fold(item.span, |bound, span| {
+            Span {
+                lo: cmp::min(bound.lo, span.lo),
+                hi: cmp::max(bound.hi, span.hi),
+                expn_id: span.expn_id,
+            }
+        })
+}
+
 pub struct FmtVisitor<'a> {
     pub parse_session: &'a ParseSess,
     pub codemap: &'a CodeMap,
@@ -510,9 +525,20 @@ impl<'a> FmtVisitor<'a> {
             // to be potentially reordered within `format_imports`. Otherwise, just format the
             // next item for output.
             if self.config.reorder_imports && is_use_item(&*items_left[0]) {
+                let reorder_imports_in_group = self.config.reorder_imports_in_group;
+                let mut last = self.codemap.lookup_line_range(item_bound(&items_left[0]));
                 let use_item_length = items_left
                     .iter()
-                    .take_while(|ppi| is_use_item(&***ppi))
+                    .take_while(|ppi| {
+                        is_use_item(&***ppi) &&
+                        (!reorder_imports_in_group ||
+                         {
+                             let current = self.codemap.lookup_line_range(item_bound(&ppi));
+                             let in_same_group = current.lo < last.hi + 2;
+                             last = current;
+                             in_same_group
+                         })
+                    })
                     .count();
                 let (use_items, rest) = items_left.split_at(use_item_length);
                 self.format_imports(use_items);

tests/source/configs-reorder_imports_in_group-false.rs

@@ -0,0 +1,13 @@
+// rustfmt-reorder_imports: true
+// rustfmt-reorder_imports_in_group: false
+// Reorder imports in group
+
+/// This comment should stay with `use std::mem;`
+use std::mem;
+use std::io;
+
+use lorem;
+/// This comment should stay with `use ipsum;`
+use ipsum;
+use dolor;
+use sit;

tests/source/configs-reorder_imports_in_group-true.rs

@@ -0,0 +1,13 @@
+// rustfmt-reorder_imports: true
+// rustfmt-reorder_imports_in_group: true
+// Reorder imports in group
+
+/// This comment should stay with `use std::mem;`
+use std::mem;
+use std::io;
+
+use lorem;
+/// This comment should stay with `use ipsum;`
+use ipsum;
+use dolor;
+use sit;

tests/target/configs-reorder_imports_in_group-false.rs

@@ -0,0 +1,13 @@
+// rustfmt-reorder_imports: true
+// rustfmt-reorder_imports_in_group: false
+// Reorder imports in group
+
+use dolor;
+/// This comment should stay with `use ipsum;`
+use ipsum;
+
+use lorem;
+use sit;
+use std::io;
+/// This comment should stay with `use std::mem;`
+use std::mem;

tests/target/configs-reorder_imports_in_group-true.rs

@@ -0,0 +1,13 @@
+// rustfmt-reorder_imports: true
+// rustfmt-reorder_imports_in_group: true
+// Reorder imports in group
+
+use std::io;
+/// This comment should stay with `use std::mem;`
+use std::mem;
+
+use dolor;
+/// This comment should stay with `use ipsum;`
+use ipsum;
+use lorem;
+use sit;