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     pub failed: bool,
  43 }
  44
  45 impl<'a> FmtVisitor<'a> {
  46     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  47         debug!("visit_stmt: {:?} {:?}",
  48                self.codemap.lookup_char_pos(stmt.span.lo),
  49                self.codemap.lookup_char_pos(stmt.span.hi));
  50
  51         // FIXME(#434): Move this check to somewhere more central, eg Rewrite.
  52         if !self.config
  53                 .file_lines
  54                 .intersects(&self.codemap.lookup_line_range(stmt.span)) {
  55             return;
  56         }
  57
  58         match stmt.node {
  59             ast::StmtKind::Item(ref item) => {
  60                 self.visit_item(item);
  61             }
  62             ast::StmtKind::Local(..) |
  63             ast::StmtKind::Expr(..) |
  64             ast::StmtKind::Semi(..) => {
  65                 let rewrite =
  66                     stmt.rewrite(&self.get_context(),
  67                                  Shape::indented(self.block_indent, self.config));
  68                 self.push_rewrite(stmt.span, rewrite);
  69             }
  70             ast::StmtKind::Mac(ref mac) => {
  71                 let (ref mac, _macro_style, _) = **mac;
  72                 self.visit_mac(mac, None, MacroPosition::Statement);
  73                 self.format_missing(stmt.span.hi);
  74             }
  75         }
  76     }
  77
  78     pub fn visit_block(&mut self, b: &ast::Block) {
  79         debug!("visit_block: {:?} {:?}",
  80                self.codemap.lookup_char_pos(b.span.lo),
  81                self.codemap.lookup_char_pos(b.span.hi));
  82
  83         // Check if this block has braces.
  84         let snippet = self.snippet(b.span);
  85         let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
  86         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
  87
  88         self.last_pos = self.last_pos + brace_compensation;
  89         self.block_indent = self.block_indent.block_indent(self.config);
  90         self.buffer.push_str("{");
  91
  92         for stmt in &b.stmts {
  93             self.visit_stmt(stmt)
  94         }
  95
  96         if !b.stmts.is_empty() {
  97             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
  98                 if utils::semicolon_for_expr(expr) {
  99                     self.buffer.push_str(";");
 100                 }
 101             }
 102         }
 103
 104         // FIXME: we should compress any newlines here to just one
 105         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation);
 106         self.close_block();
 107         self.last_pos = source!(self, b.span).hi;
 108     }
 109
 110     // FIXME: this is a terrible hack to indent the comments between the last
 111     // item in the block and the closing brace to the block's level.
 112     // The closing brace itself, however, should be indented at a shallower
 113     // level.
 114     fn close_block(&mut self) {
 115         let total_len = self.buffer.len;
 116         let chars_too_many = if self.config.hard_tabs {
 117             1
 118         } else {
 119             self.config.tab_spaces
 120         };
 121         self.buffer.truncate(total_len - chars_too_many);
 122         self.buffer.push_str("}");
 123         self.block_indent = self.block_indent.block_unindent(self.config);
 124     }
 125
 126     // Note that this only gets called for function definitions. Required methods
 127     // on traits do not get handled here.
 128     fn visit_fn(&mut self,
 129                 fk: visit::FnKind,
 130                 fd: &ast::FnDecl,
 131                 s: Span,
 132                 _: ast::NodeId,
 133                 defaultness: ast::Defaultness) {
 134         let indent = self.block_indent;
 135         let block;
 136         let rewrite = match fk {
 137             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 138                 block = b;
 139                 self.rewrite_fn(indent,
 140                                 ident,
 141                                 fd,
 142                                 generics,
 143                                 unsafety,
 144                                 constness.node,
 145                                 defaultness,
 146                                 abi,
 147                                 vis,
 148                                 codemap::mk_sp(s.lo, b.span.lo),
 149                                 &b)
 150             }
 151             visit::FnKind::Method(ident, sig, vis, b) => {
 152                 block = b;
 153                 self.rewrite_fn(indent,
 154                                 ident,
 155                                 fd,
 156                                 &sig.generics,
 157                                 sig.unsafety,
 158                                 sig.constness.node,
 159                                 defaultness,
 160                                 sig.abi,
 161                                 vis.unwrap_or(&ast::Visibility::Inherited),
 162                                 codemap::mk_sp(s.lo, b.span.lo),
 163                                 &b)
 164             }
 165             visit::FnKind::Closure(_) => unreachable!(),
 166         };
 167
 168         if let Some(fn_str) = rewrite {
 169             self.format_missing_with_indent(source!(self, s).lo);
 170             self.buffer.push_str(&fn_str);
 171             if let Some(c) = fn_str.chars().last() {
 172                 if c == '}' {
 173                     self.last_pos = source!(self, block.span).hi;
 174                     return;
 175                 }
 176             }
 177         } else {
 178             self.format_missing(source!(self, block.span).lo);
 179         }
 180
 181         self.last_pos = source!(self, block.span).lo;
 182         self.visit_block(block)
 183     }
 184
 185     pub fn visit_item(&mut self, item: &ast::Item) {
 186         // This is where we bail out if there is a skip attribute. This is only
 187         // complex in the module case. It is complex because the module could be
 188         // in a separate file and there might be attributes in both files, but
 189         // the AST lumps them all together.
 190         match item.node {
 191             ast::ItemKind::Mod(ref m) => {
 192                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 193                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 194                 if outer_file.name == inner_file.name {
 195                     // Module is inline, in this case we treat modules like any
 196                     // other item.
 197                     if self.visit_attrs(&item.attrs) {
 198                         self.push_rewrite(item.span, None);
 199                         return;
 200                     }
 201                 } else if utils::contains_skip(&item.attrs) {
 202                     // Module is not inline, but should be skipped.
 203                     return;
 204                 } else {
 205                     // Module is not inline and should not be skipped. We want
 206                     // to process only the attributes in the current file.
 207                     let attrs = item.attrs
 208                         .iter()
 209                         .filter_map(|a| {
 210                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 211                             if attr_file.name == outer_file.name {
 212                                 Some(a.clone())
 213                             } else {
 214                                 None
 215                             }
 216                         })
 217                         .collect::<Vec<_>>();
 218                     // Assert because if we should skip it should be caught by
 219                     // the above case.
 220                     assert!(!self.visit_attrs(&attrs));
 221                 }
 222             }
 223             _ => {
 224                 if self.visit_attrs(&item.attrs) {
 225                     self.push_rewrite(item.span, None);
 226                     return;
 227                 }
 228             }
 229         }
 230
 231         match item.node {
 232             ast::ItemKind::Use(ref vp) => {
 233                 self.format_import(&item.vis, vp, item.span);
 234             }
 235             ast::ItemKind::Impl(..) => {
 236                 self.format_missing_with_indent(source!(self, item.span).lo);
 237                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 238                     self.buffer.push_str(&impl_str);
 239                     self.last_pos = source!(self, item.span).hi;
 240                 }
 241             }
 242             ast::ItemKind::Trait(..) => {
 243                 self.format_missing_with_indent(item.span.lo);
 244                 if let Some(trait_str) = format_trait(&self.get_context(),
 245                                                       item,
 246                                                       self.block_indent) {
 247                     self.buffer.push_str(&trait_str);
 248                     self.last_pos = source!(self, item.span).hi;
 249                 }
 250             }
 251             ast::ItemKind::ExternCrate(_) => {
 252                 self.format_missing_with_indent(source!(self, item.span).lo);
 253                 let new_str = self.snippet(item.span);
 254                 self.buffer.push_str(&new_str);
 255                 self.last_pos = source!(self, item.span).hi;
 256             }
 257             ast::ItemKind::Struct(ref def, ref generics) => {
 258                 let rewrite = {
 259                     let indent = self.block_indent;
 260                     let context = self.get_context();
 261                     ::items::format_struct(&context,
 262                                            "struct ",
 263                                            item.ident,
 264                                            &item.vis,
 265                                            def,
 266                                            Some(generics),
 267                                            item.span,
 268                                            indent,
 269                                            None)
 270                             .map(|s| match *def {
 271                                      ast::VariantData::Tuple(..) => s + ";",
 272                                      _ => s,
 273                                  })
 274                 };
 275                 self.push_rewrite(item.span, rewrite);
 276             }
 277             ast::ItemKind::Enum(ref def, ref generics) => {
 278                 self.format_missing_with_indent(source!(self, item.span).lo);
 279                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 280                 self.last_pos = source!(self, item.span).hi;
 281             }
 282             ast::ItemKind::Mod(ref module) => {
 283                 self.format_missing_with_indent(source!(self, item.span).lo);
 284                 self.format_mod(module, &item.vis, item.span, item.ident);
 285             }
 286             ast::ItemKind::Mac(ref mac) => {
 287                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 288             }
 289             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 290                 self.format_missing_with_indent(source!(self, item.span).lo);
 291                 self.format_foreign_mod(foreign_mod, item.span);
 292             }
 293             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 294                 let rewrite = rewrite_static("static",
 295                                              &item.vis,
 296                                              item.ident,
 297                                              ty,
 298                                              mutability,
 299                                              Some(expr),
 300                                              self.block_indent,
 301                                              &self.get_context());
 302                 self.push_rewrite(item.span, rewrite);
 303             }
 304             ast::ItemKind::Const(ref ty, ref expr) => {
 305                 let rewrite = rewrite_static("const",
 306                                              &item.vis,
 307                                              item.ident,
 308                                              ty,
 309                                              ast::Mutability::Immutable,
 310                                              Some(expr),
 311                                              self.block_indent,
 312                                              &self.get_context());
 313                 self.push_rewrite(item.span, rewrite);
 314             }
 315             ast::ItemKind::DefaultImpl(..) => {
 316                 // FIXME(#78): format impl definitions.
 317             }
 318             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 319                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 320                                                     generics,
 321                                                     unsafety,
 322                                                     constness,
 323                                                     abi,
 324                                                     &item.vis,
 325                                                     body),
 326                               decl,
 327                               item.span,
 328                               item.id,
 329                               ast::Defaultness::Final)
 330             }
 331             ast::ItemKind::Ty(ref ty, ref generics) => {
 332                 let rewrite = rewrite_type_alias(&self.get_context(),
 333                                                  self.block_indent,
 334                                                  item.ident,
 335                                                  ty,
 336                                                  generics,
 337                                                  &item.vis,
 338                                                  item.span);
 339                 self.push_rewrite(item.span, rewrite);
 340             }
 341             ast::ItemKind::Union(..) => {
 342                 // FIXME(#1157): format union definitions.
 343             }
 344         }
 345     }
 346
 347     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 348         if self.visit_attrs(&ti.attrs) {
 349             self.push_rewrite(ti.span, None);
 350             return;
 351         }
 352
 353         match ti.node {
 354             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 355                 let rewrite = rewrite_static("const",
 356                                              &ast::Visibility::Inherited,
 357                                              ti.ident,
 358                                              ty,
 359                                              ast::Mutability::Immutable,
 360                                              expr_opt.as_ref(),
 361                                              self.block_indent,
 362                                              &self.get_context());
 363                 self.push_rewrite(ti.span, rewrite);
 364             }
 365             ast::TraitItemKind::Method(ref sig, None) => {
 366                 let indent = self.block_indent;
 367                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 368                 self.push_rewrite(ti.span, rewrite);
 369             }
 370             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 371                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None, body),
 372                               &sig.decl,
 373                               ti.span,
 374                               ti.id,
 375                               ast::Defaultness::Final);
 376             }
 377             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 378                 let rewrite = rewrite_associated_type(ti.ident,
 379                                                       None,
 380                                                       Some(type_param_bounds),
 381                                                       &self.get_context(),
 382                                                       self.block_indent);
 383                 self.push_rewrite(ti.span, rewrite);
 384             }
 385             ast::TraitItemKind::Macro(ref mac) => {
 386                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 387             }
 388         }
 389     }
 390
 391     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 392         if self.visit_attrs(&ii.attrs) {
 393             self.push_rewrite(ii.span, None);
 394             return;
 395         }
 396
 397         match ii.node {
 398             ast::ImplItemKind::Method(ref sig, ref body) => {
 399                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 400                               &sig.decl,
 401                               ii.span,
 402                               ii.id,
 403                               ii.defaultness);
 404             }
 405             ast::ImplItemKind::Const(ref ty, ref expr) => {
 406                 let rewrite = rewrite_static("const",
 407                                              &ii.vis,
 408                                              ii.ident,
 409                                              ty,
 410                                              ast::Mutability::Immutable,
 411                                              Some(expr),
 412                                              self.block_indent,
 413                                              &self.get_context());
 414                 self.push_rewrite(ii.span, rewrite);
 415             }
 416             ast::ImplItemKind::Type(ref ty) => {
 417                 let rewrite = rewrite_associated_impl_type(ii.ident,
 418                                                            ii.defaultness,
 419                                                            Some(ty),
 420                                                            None,
 421                                                            &self.get_context(),
 422                                                            self.block_indent);
 423                 self.push_rewrite(ii.span, rewrite);
 424             }
 425             ast::ImplItemKind::Macro(ref mac) => {
 426                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 427             }
 428         }
 429     }
 430
 431     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 432         // 1 = ;
 433         let shape = Shape::indented(self.block_indent, self.config)
 434             .sub_width(1)
 435             .unwrap();
 436         let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, 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         self.failed = match rewrite {
 443             Some(ref s) if s.rewrite(&self.get_context(),
 444                                      Shape::indented(self.block_indent, self.config))
 445                                .is_none() => true,
 446             None => true,
 447             _ => self.failed,
 448         };
 449         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 450         self.buffer.push_str(&result);
 451         self.last_pos = source!(self, span).hi;
 452     }
 453
 454     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 455         FmtVisitor {
 456             parse_session: parse_session,
 457             codemap: parse_session.codemap(),
 458             buffer: StringBuffer::new(),
 459             last_pos: BytePos(0),
 460             block_indent: Indent::empty(),
 461             config: config,
 462             failed: false,
 463         }
 464     }
 465
 466     pub fn snippet(&self, span: Span) -> String {
 467         match self.codemap.span_to_snippet(span) {
 468             Ok(s) => s,
 469             Err(_) => {
 470                 println!("Couldn't make snippet for span {:?}->{:?}",
 471                          self.codemap.lookup_char_pos(span.lo),
 472                          self.codemap.lookup_char_pos(span.hi));
 473                 "".to_owned()
 474             }
 475         }
 476     }
 477
 478     // Returns true if we should skip the following item.
 479     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 480         if utils::contains_skip(attrs) {
 481             return true;
 482         }
 483
 484         let outers: Vec<_> = attrs
 485             .iter()
 486             .filter(|a| a.style == ast::AttrStyle::Outer)
 487             .cloned()
 488             .collect();
 489         if outers.is_empty() {
 490             return false;
 491         }
 492
 493         let first = &outers[0];
 494         self.format_missing_with_indent(source!(self, first.span).lo);
 495
 496         let rewrite = outers
 497             .rewrite(&self.get_context(),
 498                      Shape::indented(self.block_indent, self.config))
 499             .unwrap();
 500         self.buffer.push_str(&rewrite);
 501         let last = outers.last().unwrap();
 502         self.last_pos = source!(self, last.span).hi;
 503         false
 504     }
 505
 506     fn walk_mod_items(&mut self, m: &ast::Mod) {
 507         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 508         while !items_left.is_empty() {
 509             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 510             // to be potentially reordered within `format_imports`. Otherwise, just format the
 511             // next item for output.
 512             if self.config.reorder_imports && is_use_item(&*items_left[0]) {
 513                 let use_item_length = items_left
 514                     .iter()
 515                     .take_while(|ppi| is_use_item(&***ppi))
 516                     .count();
 517                 let (use_items, rest) = items_left.split_at(use_item_length);
 518                 self.format_imports(use_items);
 519                 items_left = rest;
 520             } else {
 521                 // `unwrap()` is safe here because we know `items_left`
 522                 // has elements from the loop condition
 523                 let (item, rest) = items_left.split_first().unwrap();
 524                 self.visit_item(item);
 525                 items_left = rest;
 526             }
 527         }
 528     }
 529
 530     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 531         // Decide whether this is an inline mod or an external mod.
 532         let local_file_name = self.codemap.span_to_filename(s);
 533         let inner_span = source!(self, m.inner);
 534         let is_internal = !(inner_span.lo.0 == 0 && inner_span.hi.0 == 0) &&
 535                           local_file_name == self.codemap.span_to_filename(inner_span);
 536
 537         self.buffer.push_str(&*utils::format_visibility(vis));
 538         self.buffer.push_str("mod ");
 539         self.buffer.push_str(&ident.to_string());
 540
 541         if is_internal {
 542             self.buffer.push_str(" {");
 543             // Hackery to account for the closing }.
 544             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 545             let body_snippet =
 546                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 547             let body_snippet = body_snippet.trim();
 548             if body_snippet.is_empty() {
 549                 self.buffer.push_str("}");
 550             } else {
 551                 self.last_pos = mod_lo;
 552                 self.block_indent = self.block_indent.block_indent(self.config);
 553                 self.walk_mod_items(m);
 554                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 555                 self.close_block();
 556             }
 557             self.last_pos = source!(self, m.inner).hi;
 558         } else {
 559             self.buffer.push_str(";");
 560             self.last_pos = source!(self, s).hi;
 561         }
 562     }
 563
 564     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 565         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 566         self.last_pos = filemap.start_pos;
 567         self.block_indent = Indent::empty();
 568         self.walk_mod_items(m);
 569         self.format_missing_with_indent(filemap.end_pos);
 570     }
 571
 572     pub fn get_context(&self) -> RewriteContext {
 573         RewriteContext {
 574             parse_session: self.parse_session,
 575             codemap: self.codemap,
 576             config: self.config,
 577             inside_macro: false,
 578         }
 579     }
 580 }
 581
 582 impl<'a> Rewrite for [ast::Attribute] {
 583     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 584         let mut result = String::new();
 585         if self.is_empty() {
 586             return Some(result);
 587         }
 588         let indent = shape.indent.to_string(context.config);
 589
 590         for (i, a) in self.iter().enumerate() {
 591             let mut a_str = context.snippet(a.span);
 592
 593             // Write comments and blank lines between attributes.
 594             if i > 0 {
 595                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 596                 // This particular horror show is to preserve line breaks in between doc
 597                 // comments. An alternative would be to force such line breaks to start
 598                 // with the usual doc comment token.
 599                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 600                 let comment = comment.trim();
 601                 if !comment.is_empty() {
 602                     let comment = try_opt!(rewrite_comment(comment,
 603                                                            false,
 604                                                            Shape::legacy(context.config
 605                                                                              .comment_width -
 606                                                                          shape.indent.width(),
 607                                                                          shape.indent),
 608                                                            context.config));
 609                     result.push_str(&indent);
 610                     result.push_str(&comment);
 611                     result.push('\n');
 612                 } else if multi_line {
 613                     result.push('\n');
 614                 }
 615                 result.push_str(&indent);
 616             }
 617
 618             if a_str.starts_with("//") {
 619                 a_str = try_opt!(rewrite_comment(&a_str,
 620                                                  false,
 621                                                  Shape::legacy(context.config.comment_width -
 622                                                                shape.indent.width(),
 623                                                                shape.indent),
 624                                                  context.config));
 625             }
 626
 627             // Write the attribute itself.
 628             result.push_str(&a_str);
 629
 630             if i < self.len() - 1 {
 631                 result.push('\n');
 632             }
 633         }
 634
 635         Some(result)
 636     }
 637 }