src/tools/rustfmt/src/reorder.rs

   1 //! Reorder items.
   2 //!
   3 //! `mod`, `extern crate` and `use` declarations are reordered in alphabetical
   4 //! order. Trait items are reordered in pre-determined order (associated types
   5 //! and constants comes before methods).
   6
   7 // FIXME(#2455): Reorder trait items.
   8
   9 use std::cmp::{Ord, Ordering};
  10
  11 use rustc_ast::ast;
  12 use rustc_span::{symbol::sym, Span};
  13
  14 use crate::config::{Config, GroupImportsTactic};
  15 use crate::imports::{normalize_use_trees_with_granularity, UseSegmentKind, UseTree};
  16 use crate::items::{is_mod_decl, rewrite_extern_crate, rewrite_mod};
  17 use crate::lists::{itemize_list, write_list, ListFormatting, ListItem};
  18 use crate::rewrite::RewriteContext;
  19 use crate::shape::Shape;
  20 use crate::source_map::LineRangeUtils;
  21 use crate::spanned::Spanned;
  22 use crate::utils::{contains_skip, mk_sp};
  23 use crate::visitor::FmtVisitor;
  24
  25 /// Choose the ordering between the given two items.
  26 fn compare_items(a: &ast::Item, b: &ast::Item) -> Ordering {
  27     match (&a.kind, &b.kind) {
  28         (&ast::ItemKind::Mod(..), &ast::ItemKind::Mod(..)) => {
  29             a.ident.as_str().cmp(b.ident.as_str())
  30         }
  31         (&ast::ItemKind::ExternCrate(ref a_name), &ast::ItemKind::ExternCrate(ref b_name)) => {
  32             // `extern crate foo as bar;`
  33             //               ^^^ Comparing this.
  34             let a_orig_name = a_name.unwrap_or(a.ident.name);
  35             let b_orig_name = b_name.unwrap_or(b.ident.name);
  36             let result = a_orig_name.as_str().cmp(b_orig_name.as_str());
  37             if result != Ordering::Equal {
  38                 return result;
  39             }
  40
  41             // `extern crate foo as bar;`
  42             //                      ^^^ Comparing this.
  43             match (a_name, b_name) {
  44                 (Some(..), None) => Ordering::Greater,
  45                 (None, Some(..)) => Ordering::Less,
  46                 (None, None) => Ordering::Equal,
  47                 (Some(..), Some(..)) => a.ident.as_str().cmp(b.ident.as_str()),
  48             }
  49         }
  50         _ => unreachable!(),
  51     }
  52 }
  53
  54 fn wrap_reorderable_items(
  55     context: &RewriteContext<'_>,
  56     list_items: &[ListItem],
  57     shape: Shape,
  58 ) -> Option<String> {
  59     let fmt = ListFormatting::new(shape, context.config)
  60         .separator("")
  61         .align_comments(false);
  62     write_list(list_items, &fmt)
  63 }
  64
  65 fn rewrite_reorderable_item(
  66     context: &RewriteContext<'_>,
  67     item: &ast::Item,
  68     shape: Shape,
  69 ) -> Option<String> {
  70     match item.kind {
  71         ast::ItemKind::ExternCrate(..) => rewrite_extern_crate(context, item, shape),
  72         ast::ItemKind::Mod(..) => rewrite_mod(context, item, shape),
  73         _ => None,
  74     }
  75 }
  76
  77 /// Rewrite a list of items with reordering and/or regrouping. Every item
  78 /// in `items` must have the same `ast::ItemKind`. Whether reordering, regrouping,
  79 /// or both are done is determined from the `context`.
  80 fn rewrite_reorderable_or_regroupable_items(
  81     context: &RewriteContext<'_>,
  82     reorderable_items: &[&ast::Item],
  83     shape: Shape,
  84     span: Span,
  85 ) -> Option<String> {
  86     match reorderable_items[0].kind {
  87         // FIXME: Remove duplicated code.
  88         ast::ItemKind::Use(..) => {
  89             let mut normalized_items: Vec<_> = reorderable_items
  90                 .iter()
  91                 .filter_map(|item| UseTree::from_ast_with_normalization(context, item))
  92                 .collect();
  93             let cloned = normalized_items.clone();
  94             // Add comments before merging.
  95             let list_items = itemize_list(
  96                 context.snippet_provider,
  97                 cloned.iter(),
  98                 "",
  99                 ";",
 100                 |item| item.span().lo(),
 101                 |item| item.span().hi(),
 102                 |_item| Some("".to_owned()),
 103                 span.lo(),
 104                 span.hi(),
 105                 false,
 106             );
 107             for (item, list_item) in normalized_items.iter_mut().zip(list_items) {
 108                 item.list_item = Some(list_item.clone());
 109             }
 110             normalized_items = normalize_use_trees_with_granularity(
 111                 normalized_items,
 112                 context.config.imports_granularity(),
 113             );
 114
 115             let mut regrouped_items = match context.config.group_imports() {
 116                 GroupImportsTactic::Preserve | GroupImportsTactic::One => {
 117                     vec![normalized_items]
 118                 }
 119                 GroupImportsTactic::StdExternalCrate => group_imports(normalized_items),
 120             };
 121
 122             if context.config.reorder_imports() {
 123                 regrouped_items.iter_mut().for_each(|items| items.sort())
 124             }
 125
 126             // 4 = "use ", 1 = ";"
 127             let nested_shape = shape.offset_left(4)?.sub_width(1)?;
 128             let item_vec: Vec<_> = regrouped_items
 129                 .into_iter()
 130                 .filter(|use_group| !use_group.is_empty())
 131                 .map(|use_group| {
 132                     let item_vec: Vec<_> = use_group
 133                         .into_iter()
 134                         .map(|use_tree| ListItem {
 135                             item: use_tree.rewrite_top_level(context, nested_shape),
 136                             ..use_tree.list_item.unwrap_or_else(ListItem::empty)
 137                         })
 138                         .collect();
 139                     wrap_reorderable_items(context, &item_vec, nested_shape)
 140                 })
 141                 .collect::<Option<Vec<_>>>()?;
 142
 143             let join_string = format!("\n\n{}", shape.indent.to_string(context.config));
 144             Some(item_vec.join(&join_string))
 145         }
 146         _ => {
 147             let list_items = itemize_list(
 148                 context.snippet_provider,
 149                 reorderable_items.iter(),
 150                 "",
 151                 ";",
 152                 |item| item.span().lo(),
 153                 |item| item.span().hi(),
 154                 |item| rewrite_reorderable_item(context, item, shape),
 155                 span.lo(),
 156                 span.hi(),
 157                 false,
 158             );
 159
 160             let mut item_pair_vec: Vec<_> = list_items.zip(reorderable_items.iter()).collect();
 161             item_pair_vec.sort_by(|a, b| compare_items(a.1, b.1));
 162             let item_vec: Vec<_> = item_pair_vec.into_iter().map(|pair| pair.0).collect();
 163
 164             wrap_reorderable_items(context, &item_vec, shape)
 165         }
 166     }
 167 }
 168
 169 fn contains_macro_use_attr(item: &ast::Item) -> bool {
 170     crate::attr::contains_name(&item.attrs, sym::macro_use)
 171 }
 172
 173 /// Divides imports into three groups, corresponding to standard, external
 174 /// and local imports. Sorts each subgroup.
 175 fn group_imports(uts: Vec<UseTree>) -> Vec<Vec<UseTree>> {
 176     let mut std_imports = Vec::new();
 177     let mut external_imports = Vec::new();
 178     let mut local_imports = Vec::new();
 179
 180     for ut in uts.into_iter() {
 181         if ut.path.is_empty() {
 182             external_imports.push(ut);
 183             continue;
 184         }
 185         match &ut.path[0].kind {
 186             UseSegmentKind::Ident(id, _) => match id.as_ref() {
 187                 "std" | "alloc" | "core" => std_imports.push(ut),
 188                 _ => external_imports.push(ut),
 189             },
 190             UseSegmentKind::Slf(_) | UseSegmentKind::Super(_) | UseSegmentKind::Crate(_) => {
 191                 local_imports.push(ut)
 192             }
 193             // These are probably illegal here
 194             UseSegmentKind::Glob | UseSegmentKind::List(_) => external_imports.push(ut),
 195         }
 196     }
 197
 198     vec![std_imports, external_imports, local_imports]
 199 }
 200
 201 /// A simplified version of `ast::ItemKind`.
 202 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 203 enum ReorderableItemKind {
 204     ExternCrate,
 205     Mod,
 206     Use,
 207     /// An item that cannot be reordered. Either has an unreorderable item kind
 208     /// or an `macro_use` attribute.
 209     Other,
 210 }
 211
 212 impl ReorderableItemKind {
 213     fn from(item: &ast::Item) -> Self {
 214         match item.kind {
 215             _ if contains_macro_use_attr(item) | contains_skip(&item.attrs) => {
 216                 ReorderableItemKind::Other
 217             }
 218             ast::ItemKind::ExternCrate(..) => ReorderableItemKind::ExternCrate,
 219             ast::ItemKind::Mod(..) if is_mod_decl(item) => ReorderableItemKind::Mod,
 220             ast::ItemKind::Use(..) => ReorderableItemKind::Use,
 221             _ => ReorderableItemKind::Other,
 222         }
 223     }
 224
 225     fn is_same_item_kind(self, item: &ast::Item) -> bool {
 226         ReorderableItemKind::from(item) == self
 227     }
 228
 229     fn is_reorderable(self, config: &Config) -> bool {
 230         match self {
 231             ReorderableItemKind::ExternCrate => config.reorder_imports(),
 232             ReorderableItemKind::Mod => config.reorder_modules(),
 233             ReorderableItemKind::Use => config.reorder_imports(),
 234             ReorderableItemKind::Other => false,
 235         }
 236     }
 237
 238     fn is_regroupable(self, config: &Config) -> bool {
 239         match self {
 240             ReorderableItemKind::ExternCrate
 241             | ReorderableItemKind::Mod
 242             | ReorderableItemKind::Other => false,
 243             ReorderableItemKind::Use => config.group_imports() != GroupImportsTactic::Preserve,
 244         }
 245     }
 246
 247     fn in_group(self, config: &Config) -> bool {
 248         match self {
 249             ReorderableItemKind::ExternCrate | ReorderableItemKind::Mod => true,
 250             ReorderableItemKind::Use => config.group_imports() == GroupImportsTactic::Preserve,
 251             ReorderableItemKind::Other => false,
 252         }
 253     }
 254 }
 255
 256 impl<'b, 'a: 'b> FmtVisitor<'a> {
 257     /// Format items with the same item kind and reorder them, regroup them, or
 258     /// both. If `in_group` is `true`, then the items separated by an empty line
 259     /// will not be reordered together.
 260     fn walk_reorderable_or_regroupable_items(
 261         &mut self,
 262         items: &[&ast::Item],
 263         item_kind: ReorderableItemKind,
 264         in_group: bool,
 265     ) -> usize {
 266         let mut last = self.parse_sess.lookup_line_range(items[0].span());
 267         let item_length = items
 268             .iter()
 269             .take_while(|ppi| {
 270                 item_kind.is_same_item_kind(&***ppi)
 271                     && (!in_group || {
 272                         let current = self.parse_sess.lookup_line_range(ppi.span());
 273                         let in_same_group = current.lo < last.hi + 2;
 274                         last = current;
 275                         in_same_group
 276                     })
 277             })
 278             .count();
 279         let items = &items[..item_length];
 280
 281         let at_least_one_in_file_lines = items
 282             .iter()
 283             .any(|item| !out_of_file_lines_range!(self, item.span));
 284
 285         if at_least_one_in_file_lines && !items.is_empty() {
 286             let lo = items.first().unwrap().span().lo();
 287             let hi = items.last().unwrap().span().hi();
 288             let span = mk_sp(lo, hi);
 289             let rw = rewrite_reorderable_or_regroupable_items(
 290                 &self.get_context(),
 291                 items,
 292                 self.shape(),
 293                 span,
 294             );
 295             self.push_rewrite(span, rw);
 296         } else {
 297             for item in items {
 298                 self.push_rewrite(item.span, None);
 299             }
 300         }
 301
 302         item_length
 303     }
 304
 305     /// Visits and format the given items. Items are reordered If they are
 306     /// consecutive and reorderable.
 307     pub(crate) fn visit_items_with_reordering(&mut self, mut items: &[&ast::Item]) {
 308         while !items.is_empty() {
 309             // If the next item is a `use`, `extern crate` or `mod`, then extract it and any
 310             // subsequent items that have the same item kind to be reordered within
 311             // `walk_reorderable_items`. Otherwise, just format the next item for output.
 312             let item_kind = ReorderableItemKind::from(items[0]);
 313             if item_kind.is_reorderable(self.config) || item_kind.is_regroupable(self.config) {
 314                 let visited_items_num = self.walk_reorderable_or_regroupable_items(
 315                     items,
 316                     item_kind,
 317                     item_kind.in_group(self.config),
 318                 );
 319                 let (_, rest) = items.split_at(visited_items_num);
 320                 items = rest;
 321             } else {
 322                 // Reaching here means items were not reordered. There must be at least
 323                 // one item left in `items`, so calling `unwrap()` here is safe.
 324                 let (item, rest) = items.split_first().unwrap();
 325                 self.visit_item(item);
 326                 items = rest;
 327             }
 328         }
 329     }
 330 }