src/visitor.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use syntax::{ast, ptr, visit};
  12 use syntax::codemap::{self, CodeMap, Span, BytePos};
  13 use syntax::parse::ParseSess;
  14
  15 use strings::string_buffer::StringBuffer;
  16
  17 use {Indent, Shape};
  18 use utils;
  19 use codemap::{LineRangeUtils, SpanUtils};
  20 use config::Config;
  21 use rewrite::{Rewrite, RewriteContext};
  22 use comment::rewrite_comment;
  23 use macros::{rewrite_macro, MacroPosition};
  24 use items::{rewrite_static, rewrite_associated_type, rewrite_associated_impl_type,
  25             rewrite_type_alias, format_impl, format_trait};
  26
  27 fn is_use_item(item: &ast::Item) -> bool {
  28     match item.node {
  29         ast::ItemKind::Use(_) => true,
  30         _ => false,
  31     }
  32 }
  33
  34 pub struct FmtVisitor<'a> {
  35     pub parse_session: &'a ParseSess,
  36     pub codemap: &'a CodeMap,
  37     pub buffer: StringBuffer,
  38     pub last_pos: BytePos,
  39     // FIXME: use an RAII util or closure for indenting
  40     pub block_indent: Indent,
  41     pub config: &'a Config,
  42 }
  43
  44 impl<'a> FmtVisitor<'a> {
  45     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  46         debug!("visit_stmt: {:?} {:?}",
  47                self.codemap.lookup_char_pos(stmt.span.lo),
  48                self.codemap.lookup_char_pos(stmt.span.hi));
  49
  50         // FIXME(#434): Move this check to somewhere more central, eg Rewrite.
  51         if !self.config.file_lines.contains(&self.codemap.lookup_line_range(stmt.span)) {
  52             return;
  53         }
  54
  55         match stmt.node {
  56             ast::StmtKind::Item(ref item) => {
  57                 self.visit_item(item);
  58             }
  59             ast::StmtKind::Local(..) |
  60             ast::StmtKind::Expr(..) |
  61             ast::StmtKind::Semi(..) => {
  62                 let rewrite = stmt.rewrite(&self.get_context(),
  63                                            Shape::legacy(self.config.max_width -
  64                                                          self.block_indent.width(),
  65                                                          self.block_indent));
  66                 self.push_rewrite(stmt.span, rewrite);
  67             }
  68             ast::StmtKind::Mac(ref mac) => {
  69                 let (ref mac, _macro_style, _) = **mac;
  70                 self.visit_mac(mac, None, MacroPosition::Statement);
  71                 self.format_missing(stmt.span.hi);
  72             }
  73         }
  74     }
  75
  76     pub fn visit_block(&mut self, b: &ast::Block) {
  77         debug!("visit_block: {:?} {:?}",
  78                self.codemap.lookup_char_pos(b.span.lo),
  79                self.codemap.lookup_char_pos(b.span.hi));
  80
  81         // Check if this block has braces.
  82         let snippet = self.snippet(b.span);
  83         let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
  84         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
  85
  86         self.last_pos = self.last_pos + brace_compensation;
  87         self.block_indent = self.block_indent.block_indent(self.config);
  88         self.buffer.push_str("{");
  89
  90         for stmt in &b.stmts {
  91             self.visit_stmt(stmt)
  92         }
  93
  94         if !b.stmts.is_empty() {
  95             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
  96                 if utils::semicolon_for_expr(expr) {
  97                     self.buffer.push_str(";");
  98                 }
  99             }
 100         }
 101
 102         // FIXME: we should compress any newlines here to just one
 103         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation);
 104         self.close_block();
 105         self.last_pos = source!(self, b.span).hi;
 106     }
 107
 108     // FIXME: this is a terrible hack to indent the comments between the last
 109     // item in the block and the closing brace to the block's level.
 110     // The closing brace itself, however, should be indented at a shallower
 111     // level.
 112     fn close_block(&mut self) {
 113         let total_len = self.buffer.len;
 114         let chars_too_many = if self.config.hard_tabs {
 115             1
 116         } else {
 117             self.config.tab_spaces
 118         };
 119         self.buffer.truncate(total_len - chars_too_many);
 120         self.buffer.push_str("}");
 121         self.block_indent = self.block_indent.block_unindent(self.config);
 122     }
 123
 124     // Note that this only gets called for function definitions. Required methods
 125     // on traits do not get handled here.
 126     fn visit_fn(&mut self,
 127                 fk: visit::FnKind,
 128                 fd: &ast::FnDecl,
 129                 s: Span,
 130                 _: ast::NodeId,
 131                 defaultness: ast::Defaultness) {
 132         let indent = self.block_indent;
 133         let block;
 134         let rewrite = match fk {
 135             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 136                 block = b;
 137                 self.rewrite_fn(indent,
 138                                 ident,
 139                                 fd,
 140                                 generics,
 141                                 unsafety,
 142                                 constness.node,
 143                                 defaultness,
 144                                 abi,
 145                                 vis,
 146                                 codemap::mk_sp(s.lo, b.span.lo),
 147                                 &b)
 148             }
 149             visit::FnKind::Method(ident, sig, vis, b) => {
 150                 block = b;
 151                 self.rewrite_fn(indent,
 152                                 ident,
 153                                 fd,
 154                                 &sig.generics,
 155                                 sig.unsafety,
 156                                 sig.constness.node,
 157                                 defaultness,
 158                                 sig.abi,
 159                                 vis.unwrap_or(&ast::Visibility::Inherited),
 160                                 codemap::mk_sp(s.lo, b.span.lo),
 161                                 &b)
 162             }
 163             visit::FnKind::Closure(_) => unreachable!(),
 164         };
 165
 166         if let Some(fn_str) = rewrite {
 167             self.format_missing_with_indent(source!(self, s).lo);
 168             self.buffer.push_str(&fn_str);
 169             if let Some(c) = fn_str.chars().last() {
 170                 if c == '}' {
 171                     self.last_pos = source!(self, block.span).hi;
 172                     return;
 173                 }
 174             }
 175         } else {
 176             self.format_missing(source!(self, block.span).lo);
 177         }
 178
 179         self.last_pos = source!(self, block.span).lo;
 180         self.visit_block(block)
 181     }
 182
 183     pub fn visit_item(&mut self, item: &ast::Item) {
 184         // This is where we bail out if there is a skip attribute. This is only
 185         // complex in the module case. It is complex because the module could be
 186         // in a separate file and there might be attributes in both files, but
 187         // the AST lumps them all together.
 188         match item.node {
 189             ast::ItemKind::Mod(ref m) => {
 190                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 191                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 192                 if outer_file.name == inner_file.name {
 193                     // Module is inline, in this case we treat modules like any
 194                     // other item.
 195                     if self.visit_attrs(&item.attrs) {
 196                         self.push_rewrite(item.span, None);
 197                         return;
 198                     }
 199                 } else if utils::contains_skip(&item.attrs) {
 200                     // Module is not inline, but should be skipped.
 201                     return;
 202                 } else {
 203                     // Module is not inline and should not be skipped. We want
 204                     // to process only the attributes in the current file.
 205                     let attrs = item.attrs
 206                         .iter()
 207                         .filter_map(|a| {
 208                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 209                             if attr_file.name == outer_file.name {
 210                                 Some(a.clone())
 211                             } else {
 212                                 None
 213                             }
 214                         })
 215                         .collect::<Vec<_>>();
 216                     // Assert because if we should skip it should be caught by
 217                     // the above case.
 218                     assert!(!self.visit_attrs(&attrs));
 219                 }
 220             }
 221             _ => {
 222                 if self.visit_attrs(&item.attrs) {
 223                     self.push_rewrite(item.span, None);
 224                     return;
 225                 }
 226             }
 227         }
 228
 229         match item.node {
 230             ast::ItemKind::Use(ref vp) => {
 231                 self.format_import(&item.vis, vp, item.span);
 232             }
 233             ast::ItemKind::Impl(..) => {
 234                 self.format_missing_with_indent(source!(self, item.span).lo);
 235                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 236                     self.buffer.push_str(&impl_str);
 237                     self.last_pos = source!(self, item.span).hi;
 238                 }
 239             }
 240             ast::ItemKind::Trait(..) => {
 241                 self.format_missing_with_indent(item.span.lo);
 242                 if let Some(trait_str) = format_trait(&self.get_context(),
 243                                                       item,
 244                                                       self.block_indent) {
 245                     self.buffer.push_str(&trait_str);
 246                     self.last_pos = source!(self, item.span).hi;
 247                 }
 248             }
 249             ast::ItemKind::ExternCrate(_) => {
 250                 self.format_missing_with_indent(source!(self, item.span).lo);
 251                 let new_str = self.snippet(item.span);
 252                 self.buffer.push_str(&new_str);
 253                 self.last_pos = source!(self, item.span).hi;
 254             }
 255             ast::ItemKind::Struct(ref def, ref generics) => {
 256                 let rewrite = {
 257                     let indent = self.block_indent;
 258                     let context = self.get_context();
 259                     ::items::format_struct(&context,
 260                                            "struct ",
 261                                            item.ident,
 262                                            &item.vis,
 263                                            def,
 264                                            Some(generics),
 265                                            item.span,
 266                                            indent,
 267                                            None)
 268                             .map(|s| match *def {
 269                                      ast::VariantData::Tuple(..) => s + ";",
 270                                      _ => s,
 271                                  })
 272                 };
 273                 self.push_rewrite(item.span, rewrite);
 274             }
 275             ast::ItemKind::Enum(ref def, ref generics) => {
 276                 self.format_missing_with_indent(source!(self, item.span).lo);
 277                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 278                 self.last_pos = source!(self, item.span).hi;
 279             }
 280             ast::ItemKind::Mod(ref module) => {
 281                 self.format_missing_with_indent(source!(self, item.span).lo);
 282                 self.format_mod(module, &item.vis, item.span, item.ident);
 283             }
 284             ast::ItemKind::Mac(ref mac) => {
 285                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 286             }
 287             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 288                 self.format_missing_with_indent(source!(self, item.span).lo);
 289                 self.format_foreign_mod(foreign_mod, item.span);
 290             }
 291             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 292                 let rewrite = rewrite_static("static",
 293                                              &item.vis,
 294                                              item.ident,
 295                                              ty,
 296                                              mutability,
 297                                              Some(expr),
 298                                              self.block_indent,
 299                                              &self.get_context());
 300                 self.push_rewrite(item.span, rewrite);
 301             }
 302             ast::ItemKind::Const(ref ty, ref expr) => {
 303                 let rewrite = rewrite_static("const",
 304                                              &item.vis,
 305                                              item.ident,
 306                                              ty,
 307                                              ast::Mutability::Immutable,
 308                                              Some(expr),
 309                                              self.block_indent,
 310                                              &self.get_context());
 311                 self.push_rewrite(item.span, rewrite);
 312             }
 313             ast::ItemKind::DefaultImpl(..) => {
 314                 // FIXME(#78): format impl definitions.
 315             }
 316             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 317                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 318                                                     generics,
 319                                                     unsafety,
 320                                                     constness,
 321                                                     abi,
 322                                                     &item.vis,
 323                                                     body),
 324                               decl,
 325                               item.span,
 326                               item.id,
 327                               ast::Defaultness::Final)
 328             }
 329             ast::ItemKind::Ty(ref ty, ref generics) => {
 330                 let rewrite = rewrite_type_alias(&self.get_context(),
 331                                                  self.block_indent,
 332                                                  item.ident,
 333                                                  ty,
 334                                                  generics,
 335                                                  &item.vis,
 336                                                  item.span);
 337                 self.push_rewrite(item.span, rewrite);
 338             }
 339             ast::ItemKind::Union(..) => {
 340                 // FIXME(#1157): format union definitions.
 341             }
 342         }
 343     }
 344
 345     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 346         if self.visit_attrs(&ti.attrs) {
 347             self.push_rewrite(ti.span, None);
 348             return;
 349         }
 350
 351         match ti.node {
 352             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 353                 let rewrite = rewrite_static("const",
 354                                              &ast::Visibility::Inherited,
 355                                              ti.ident,
 356                                              ty,
 357                                              ast::Mutability::Immutable,
 358                                              expr_opt.as_ref(),
 359                                              self.block_indent,
 360                                              &self.get_context());
 361                 self.push_rewrite(ti.span, rewrite);
 362             }
 363             ast::TraitItemKind::Method(ref sig, None) => {
 364                 let indent = self.block_indent;
 365                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 366                 self.push_rewrite(ti.span, rewrite);
 367             }
 368             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 369                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None, body),
 370                               &sig.decl,
 371                               ti.span,
 372                               ti.id,
 373                               ast::Defaultness::Final);
 374             }
 375             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 376                 let rewrite = rewrite_associated_type(ti.ident,
 377                                                       None,
 378                                                       Some(type_param_bounds),
 379                                                       &self.get_context(),
 380                                                       self.block_indent);
 381                 self.push_rewrite(ti.span, rewrite);
 382             }
 383             ast::TraitItemKind::Macro(..) => {
 384                 // FIXME(#1158) Macros in trait item position
 385             }
 386         }
 387     }
 388
 389     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 390         if self.visit_attrs(&ii.attrs) {
 391             self.push_rewrite(ii.span, None);
 392             return;
 393         }
 394
 395         match ii.node {
 396             ast::ImplItemKind::Method(ref sig, ref body) => {
 397                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 398                               &sig.decl,
 399                               ii.span,
 400                               ii.id,
 401                               ii.defaultness);
 402             }
 403             ast::ImplItemKind::Const(ref ty, ref expr) => {
 404                 let rewrite = rewrite_static("const",
 405                                              &ii.vis,
 406                                              ii.ident,
 407                                              ty,
 408                                              ast::Mutability::Immutable,
 409                                              Some(expr),
 410                                              self.block_indent,
 411                                              &self.get_context());
 412                 self.push_rewrite(ii.span, rewrite);
 413             }
 414             ast::ImplItemKind::Type(ref ty) => {
 415                 let rewrite = rewrite_associated_impl_type(ii.ident,
 416                                                            ii.defaultness,
 417                                                            Some(ty),
 418                                                            None,
 419                                                            &self.get_context(),
 420                                                            self.block_indent);
 421                 self.push_rewrite(ii.span, rewrite);
 422             }
 423             ast::ImplItemKind::Macro(ref mac) => {
 424                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 425             }
 426         }
 427     }
 428
 429     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 430         // 1 = ;
 431         let width = self.config.max_width - self.block_indent.width() - 1;
 432         let rewrite = rewrite_macro(mac,
 433                                     ident,
 434                                     &self.get_context(),
 435                                     Shape::legacy(width, self.block_indent),
 436                                     pos);
 437         self.push_rewrite(mac.span, rewrite);
 438     }
 439
 440     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 441         self.format_missing_with_indent(source!(self, span).lo);
 442         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 443         self.buffer.push_str(&result);
 444         self.last_pos = source!(self, span).hi;
 445     }
 446
 447     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 448         FmtVisitor {
 449             parse_session: parse_session,
 450             codemap: parse_session.codemap(),
 451             buffer: StringBuffer::new(),
 452             last_pos: BytePos(0),
 453             block_indent: Indent {
 454                 block_indent: 0,
 455                 alignment: 0,
 456             },
 457             config: config,
 458         }
 459     }
 460
 461     pub fn snippet(&self, span: Span) -> String {
 462         match self.codemap.span_to_snippet(span) {
 463             Ok(s) => s,
 464             Err(_) => {
 465                 println!("Couldn't make snippet for span {:?}->{:?}",
 466                          self.codemap.lookup_char_pos(span.lo),
 467                          self.codemap.lookup_char_pos(span.hi));
 468                 "".to_owned()
 469             }
 470         }
 471     }
 472
 473     // Returns true if we should skip the following item.
 474     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 475         if utils::contains_skip(attrs) {
 476             return true;
 477         }
 478
 479         let outers: Vec<_> = attrs.iter()
 480             .filter(|a| a.style == ast::AttrStyle::Outer)
 481             .cloned()
 482             .collect();
 483         if outers.is_empty() {
 484             return false;
 485         }
 486
 487         let first = &outers[0];
 488         self.format_missing_with_indent(source!(self, first.span).lo);
 489
 490         let rewrite = outers.rewrite(&self.get_context(),
 491                                      Shape::legacy(self.config.max_width -
 492                                                    self.block_indent.width(),
 493                                                    self.block_indent))
 494             .unwrap();
 495         self.buffer.push_str(&rewrite);
 496         let last = outers.last().unwrap();
 497         self.last_pos = source!(self, last.span).hi;
 498         false
 499     }
 500
 501     fn walk_mod_items(&mut self, m: &ast::Mod) {
 502         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 503         while !items_left.is_empty() {
 504             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 505             // to be potentially reordered within `format_imports`. Otherwise, just format the
 506             // next item for output.
 507             if self.config.reorder_imports && is_use_item(&*items_left[0]) {
 508                 let use_item_length =
 509                     items_left.iter().take_while(|ppi| is_use_item(&***ppi)).count();
 510                 let (use_items, rest) = items_left.split_at(use_item_length);
 511                 self.format_imports(use_items);
 512                 items_left = rest;
 513             } else {
 514                 // `unwrap()` is safe here because we know `items_left`
 515                 // has elements from the loop condition
 516                 let (item, rest) = items_left.split_first().unwrap();
 517                 self.visit_item(item);
 518                 items_left = rest;
 519             }
 520         }
 521     }
 522
 523     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 524         // Decide whether this is an inline mod or an external mod.
 525         let local_file_name = self.codemap.span_to_filename(s);
 526         let inner_span = source!(self, m.inner);
 527         let is_internal = !(inner_span.lo.0 == 0 && inner_span.hi.0 == 0) &&
 528                           local_file_name == self.codemap.span_to_filename(inner_span);
 529
 530         self.buffer.push_str(&*utils::format_visibility(vis));
 531         self.buffer.push_str("mod ");
 532         self.buffer.push_str(&ident.to_string());
 533
 534         if is_internal {
 535             self.buffer.push_str(" {");
 536             // Hackery to account for the closing }.
 537             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 538             let body_snippet =
 539                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 540             let body_snippet = body_snippet.trim();
 541             if body_snippet.is_empty() {
 542                 self.buffer.push_str("}");
 543             } else {
 544                 self.last_pos = mod_lo;
 545                 self.block_indent = self.block_indent.block_indent(self.config);
 546                 self.walk_mod_items(m);
 547                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 548                 self.close_block();
 549             }
 550             self.last_pos = source!(self, m.inner).hi;
 551         } else {
 552             self.buffer.push_str(";");
 553             self.last_pos = source!(self, s).hi;
 554         }
 555     }
 556
 557     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 558         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 559         self.last_pos = filemap.start_pos;
 560         self.block_indent = Indent::empty();
 561         self.walk_mod_items(m);
 562         self.format_missing_with_indent(filemap.end_pos);
 563     }
 564
 565     pub fn get_context(&self) -> RewriteContext {
 566         RewriteContext {
 567             parse_session: self.parse_session,
 568             codemap: self.codemap,
 569             config: self.config,
 570         }
 571     }
 572 }
 573
 574 impl<'a> Rewrite for [ast::Attribute] {
 575     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 576         let mut result = String::new();
 577         if self.is_empty() {
 578             return Some(result);
 579         }
 580         let indent = shape.indent.to_string(context.config);
 581
 582         for (i, a) in self.iter().enumerate() {
 583             let mut a_str = context.snippet(a.span);
 584
 585             // Write comments and blank lines between attributes.
 586             if i > 0 {
 587                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 588                 // This particular horror show is to preserve line breaks in between doc
 589                 // comments. An alternative would be to force such line breaks to start
 590                 // with the usual doc comment token.
 591                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 592                 let comment = comment.trim();
 593                 if !comment.is_empty() {
 594                     let comment = try_opt!(rewrite_comment(comment,
 595                                                            false,
 596                                                            Shape::legacy(context.config
 597                                                                              .comment_width -
 598                                                                          shape.indent.width(),
 599                                                                          shape.indent),
 600                                                            context.config));
 601                     result.push_str(&indent);
 602                     result.push_str(&comment);
 603                     result.push('\n');
 604                 } else if multi_line {
 605                     result.push('\n');
 606                 }
 607                 result.push_str(&indent);
 608             }
 609
 610             if a_str.starts_with("//") {
 611                 a_str = try_opt!(rewrite_comment(&a_str,
 612                                                  false,
 613                                                  Shape::legacy(context.config.comment_width -
 614                                                                shape.indent.width(),
 615                                                                shape.indent),
 616                                                  context.config));
 617             }
 618
 619             // Write the attribute itself.
 620             result.push_str(&a_str);
 621
 622             if i < self.len() - 1 {
 623                 result.push('\n');
 624             }
 625         }
 626
 627         Some(result)
 628     }
 629 }