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