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_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                                            Shape::legacy(self.config.max_width -
  63                                                          self.block_indent.width(),
  64                                                          self.block_indent));
  65                 self.push_rewrite(stmt.span, rewrite);
  66             }
  67             ast::StmtKind::Mac(ref mac) => {
  68                 let (ref mac, _macro_style, _) = **mac;
  69                 self.visit_mac(mac, None, MacroPosition::Statement);
  70                 self.format_missing(stmt.span.hi);
  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                 s: Span,
 129                 _: ast::NodeId,
 130                 defaultness: ast::Defaultness) {
 131         let indent = self.block_indent;
 132         let block;
 133         let rewrite = match fk {
 134             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 135                 block = b;
 136                 self.rewrite_fn(indent,
 137                                 ident,
 138                                 fd,
 139                                 generics,
 140                                 unsafety,
 141                                 constness.node,
 142                                 defaultness,
 143                                 abi,
 144                                 vis,
 145                                 codemap::mk_sp(s.lo, b.span.lo),
 146                                 &b)
 147             }
 148             visit::FnKind::Method(ident, sig, vis, b) => {
 149                 block = b;
 150                 self.rewrite_fn(indent,
 151                                 ident,
 152                                 fd,
 153                                 &sig.generics,
 154                                 sig.unsafety,
 155                                 sig.constness.node,
 156                                 defaultness,
 157                                 sig.abi,
 158                                 vis.unwrap_or(&ast::Visibility::Inherited),
 159                                 codemap::mk_sp(s.lo, b.span.lo),
 160                                 &b)
 161             }
 162             visit::FnKind::Closure(_) => unreachable!(),
 163         };
 164
 165         if let Some(fn_str) = rewrite {
 166             self.format_missing_with_indent(source!(self, s).lo);
 167             self.buffer.push_str(&fn_str);
 168             if let Some(c) = fn_str.chars().last() {
 169                 if c == '}' {
 170                     self.last_pos = source!(self, block.span).hi;
 171                     return;
 172                 }
 173             }
 174         } else {
 175             self.format_missing(source!(self, block.span).lo);
 176         }
 177
 178         self.last_pos = source!(self, block.span).lo;
 179         self.visit_block(block)
 180     }
 181
 182     pub fn visit_item(&mut self, item: &ast::Item) {
 183         // This is where we bail out if there is a skip attribute. This is only
 184         // complex in the module case. It is complex because the module could be
 185         // in a separate file and there might be attributes in both files, but
 186         // the AST lumps them all together.
 187         match item.node {
 188             ast::ItemKind::Mod(ref m) => {
 189                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 190                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 191                 if outer_file.name == inner_file.name {
 192                     // Module is inline, in this case we treat modules like any
 193                     // other item.
 194                     if self.visit_attrs(&item.attrs) {
 195                         self.push_rewrite(item.span, None);
 196                         return;
 197                     }
 198                 } else if utils::contains_skip(&item.attrs) {
 199                     // Module is not inline, but should be skipped.
 200                     return;
 201                 } else {
 202                     // Module is not inline and should not be skipped. We want
 203                     // to process only the attributes in the current file.
 204                     let attrs = item.attrs
 205                         .iter()
 206                         .filter_map(|a| {
 207                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 208                             if attr_file.name == outer_file.name {
 209                                 Some(a.clone())
 210                             } else {
 211                                 None
 212                             }
 213                         })
 214                         .collect::<Vec<_>>();
 215                     // Assert because if we should skip it should be caught by
 216                     // the above case.
 217                     assert!(!self.visit_attrs(&attrs));
 218                 }
 219             }
 220             _ => {
 221                 if self.visit_attrs(&item.attrs) {
 222                     self.push_rewrite(item.span, None);
 223                     return;
 224                 }
 225             }
 226         }
 227
 228         match item.node {
 229             ast::ItemKind::Use(ref vp) => {
 230                 self.format_import(&item.vis, vp, item.span);
 231             }
 232             ast::ItemKind::Impl(..) => {
 233                 self.format_missing_with_indent(source!(self, item.span).lo);
 234                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 235                     self.buffer.push_str(&impl_str);
 236                     self.last_pos = source!(self, item.span).hi;
 237                 }
 238             }
 239             ast::ItemKind::Trait(..) => {
 240                 self.format_missing_with_indent(item.span.lo);
 241                 if let Some(trait_str) = format_trait(&self.get_context(),
 242                                                       item,
 243                                                       self.block_indent) {
 244                     self.buffer.push_str(&trait_str);
 245                     self.last_pos = source!(self, item.span).hi;
 246                 }
 247             }
 248             ast::ItemKind::ExternCrate(_) => {
 249                 self.format_missing_with_indent(source!(self, item.span).lo);
 250                 let new_str = self.snippet(item.span);
 251                 self.buffer.push_str(&new_str);
 252                 self.last_pos = source!(self, item.span).hi;
 253             }
 254             ast::ItemKind::Struct(ref def, ref generics) => {
 255                 let rewrite = {
 256                     let indent = self.block_indent;
 257                     let context = self.get_context();
 258                     ::items::format_struct(&context,
 259                                            "struct ",
 260                                            item.ident,
 261                                            &item.vis,
 262                                            def,
 263                                            Some(generics),
 264                                            item.span,
 265                                            indent,
 266                                            None)
 267                             .map(|s| match *def {
 268                                      ast::VariantData::Tuple(..) => s + ";",
 269                                      _ => s,
 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.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 285             }
 286             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 287                 self.format_missing_with_indent(source!(self, item.span).lo);
 288                 self.format_foreign_mod(foreign_mod, item.span);
 289             }
 290             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 291                 let rewrite = rewrite_static("static",
 292                                              &item.vis,
 293                                              item.ident,
 294                                              ty,
 295                                              mutability,
 296                                              Some(expr),
 297                                              self.block_indent,
 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.block_indent,
 309                                              &self.get_context());
 310                 self.push_rewrite(item.span, rewrite);
 311             }
 312             ast::ItemKind::DefaultImpl(..) => {
 313                 // FIXME(#78): format impl definitions.
 314             }
 315             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 316                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 317                                                     generics,
 318                                                     unsafety,
 319                                                     constness,
 320                                                     abi,
 321                                                     &item.vis,
 322                                                     body),
 323                               decl,
 324                               item.span,
 325                               item.id,
 326                               ast::Defaultness::Final)
 327             }
 328             ast::ItemKind::Ty(ref ty, ref generics) => {
 329                 let rewrite = rewrite_type_alias(&self.get_context(),
 330                                                  self.block_indent,
 331                                                  item.ident,
 332                                                  ty,
 333                                                  generics,
 334                                                  &item.vis,
 335                                                  item.span);
 336                 self.push_rewrite(item.span, rewrite);
 337             }
 338             ast::ItemKind::Union(..) => {
 339                 // FIXME(#1157): format union definitions.
 340             }
 341         }
 342     }
 343
 344     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 345         if self.visit_attrs(&ti.attrs) {
 346             self.push_rewrite(ti.span, None);
 347             return;
 348         }
 349
 350         match ti.node {
 351             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 352                 let rewrite = rewrite_static("const",
 353                                              &ast::Visibility::Inherited,
 354                                              ti.ident,
 355                                              ty,
 356                                              ast::Mutability::Immutable,
 357                                              expr_opt.as_ref(),
 358                                              self.block_indent,
 359                                              &self.get_context());
 360                 self.push_rewrite(ti.span, rewrite);
 361             }
 362             ast::TraitItemKind::Method(ref sig, None) => {
 363                 let indent = self.block_indent;
 364                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 365                 self.push_rewrite(ti.span, rewrite);
 366             }
 367             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 368                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None, body),
 369                               &sig.decl,
 370                               ti.span,
 371                               ti.id,
 372                               ast::Defaultness::Final);
 373             }
 374             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 375                 let rewrite = rewrite_associated_type(ti.ident,
 376                                                       None,
 377                                                       Some(type_param_bounds),
 378                                                       &self.get_context(),
 379                                                       self.block_indent);
 380                 self.push_rewrite(ti.span, rewrite);
 381             }
 382             ast::TraitItemKind::Macro(..) => {
 383                 // FIXME(#1158) Macros in trait item position
 384             }
 385         }
 386     }
 387
 388     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 389         if self.visit_attrs(&ii.attrs) {
 390             self.push_rewrite(ii.span, None);
 391             return;
 392         }
 393
 394         match ii.node {
 395             ast::ImplItemKind::Method(ref sig, ref body) => {
 396                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 397                               &sig.decl,
 398                               ii.span,
 399                               ii.id,
 400                               ii.defaultness);
 401             }
 402             ast::ImplItemKind::Const(ref ty, ref expr) => {
 403                 let rewrite = rewrite_static("const",
 404                                              &ii.vis,
 405                                              ii.ident,
 406                                              ty,
 407                                              ast::Mutability::Immutable,
 408                                              Some(expr),
 409                                              self.block_indent,
 410                                              &self.get_context());
 411                 self.push_rewrite(ii.span, rewrite);
 412             }
 413             ast::ImplItemKind::Type(ref ty) => {
 414                 let rewrite = rewrite_associated_type(ii.ident,
 415                                                       Some(ty),
 416                                                       None,
 417                                                       &self.get_context(),
 418                                                       self.block_indent);
 419                 self.push_rewrite(ii.span, rewrite);
 420             }
 421             ast::ImplItemKind::Macro(ref mac) => {
 422                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 423             }
 424         }
 425     }
 426
 427     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 428         // 1 = ;
 429         let width = self.config.max_width - self.block_indent.width() - 1;
 430         let rewrite = rewrite_macro(mac,
 431                                     ident,
 432                                     &self.get_context(),
 433                                     Shape::legacy(width, self.block_indent),
 434                                     pos);
 435         self.push_rewrite(mac.span, rewrite);
 436     }
 437
 438     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 439         self.format_missing_with_indent(source!(self, span).lo);
 440         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 441         self.buffer.push_str(&result);
 442         self.last_pos = source!(self, span).hi;
 443     }
 444
 445     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 446         FmtVisitor {
 447             parse_session: parse_session,
 448             codemap: parse_session.codemap(),
 449             buffer: StringBuffer::new(),
 450             last_pos: BytePos(0),
 451             block_indent: Indent {
 452                 block_indent: 0,
 453                 alignment: 0,
 454             },
 455             config: config,
 456         }
 457     }
 458
 459     pub fn snippet(&self, span: Span) -> String {
 460         match self.codemap.span_to_snippet(span) {
 461             Ok(s) => s,
 462             Err(_) => {
 463                 println!("Couldn't make snippet for span {:?}->{:?}",
 464                          self.codemap.lookup_char_pos(span.lo),
 465                          self.codemap.lookup_char_pos(span.hi));
 466                 "".to_owned()
 467             }
 468         }
 469     }
 470
 471     // Returns true if we should skip the following item.
 472     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 473         if utils::contains_skip(attrs) {
 474             return true;
 475         }
 476
 477         let outers: Vec<_> = attrs.iter()
 478             .filter(|a| a.style == ast::AttrStyle::Outer)
 479             .cloned()
 480             .collect();
 481         if outers.is_empty() {
 482             return false;
 483         }
 484
 485         let first = &outers[0];
 486         self.format_missing_with_indent(source!(self, first.span).lo);
 487
 488         let rewrite = outers.rewrite(&self.get_context(),
 489                                      Shape::legacy(self.config.max_width -
 490                                                    self.block_indent.width(),
 491                                                    self.block_indent))
 492             .unwrap();
 493         self.buffer.push_str(&rewrite);
 494         let last = outers.last().unwrap();
 495         self.last_pos = source!(self, last.span).hi;
 496         false
 497     }
 498
 499     fn walk_mod_items(&mut self, m: &ast::Mod) {
 500         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 501         while !items_left.is_empty() {
 502             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 503             // to be potentially reordered within `format_imports`. Otherwise, just format the
 504             // next item for output.
 505             if self.config.reorder_imports && is_use_item(&*items_left[0]) {
 506                 let use_item_length =
 507                     items_left.iter().take_while(|ppi| is_use_item(&***ppi)).count();
 508                 let (use_items, rest) = items_left.split_at(use_item_length);
 509                 self.format_imports(use_items);
 510                 items_left = rest;
 511             } else {
 512                 // `unwrap()` is safe here because we know `items_left`
 513                 // has elements from the loop condition
 514                 let (item, rest) = items_left.split_first().unwrap();
 515                 self.visit_item(item);
 516                 items_left = rest;
 517             }
 518         }
 519     }
 520
 521     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 522         // Decide whether this is an inline mod or an external mod.
 523         let local_file_name = self.codemap.span_to_filename(s);
 524         let inner_span = source!(self, m.inner);
 525         let is_internal = !(inner_span.lo.0 == 0 && inner_span.hi.0 == 0) &&
 526                           local_file_name == self.codemap.span_to_filename(inner_span);
 527
 528         self.buffer.push_str(&*utils::format_visibility(vis));
 529         self.buffer.push_str("mod ");
 530         self.buffer.push_str(&ident.to_string());
 531
 532         if is_internal {
 533             self.buffer.push_str(" {");
 534             // Hackery to account for the closing }.
 535             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 536             let body_snippet =
 537                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 538             let body_snippet = body_snippet.trim();
 539             if body_snippet.is_empty() {
 540                 self.buffer.push_str("}");
 541             } else {
 542                 self.last_pos = mod_lo;
 543                 self.block_indent = self.block_indent.block_indent(self.config);
 544                 self.walk_mod_items(m);
 545                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 546                 self.close_block();
 547             }
 548             self.last_pos = source!(self, m.inner).hi;
 549         } else {
 550             self.buffer.push_str(";");
 551             self.last_pos = source!(self, s).hi;
 552         }
 553     }
 554
 555     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 556         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 557         self.last_pos = filemap.start_pos;
 558         self.block_indent = Indent::empty();
 559         self.walk_mod_items(m);
 560         self.format_missing_with_indent(filemap.end_pos);
 561     }
 562
 563     pub fn get_context(&self) -> RewriteContext {
 564         RewriteContext {
 565             parse_session: self.parse_session,
 566             codemap: self.codemap,
 567             config: self.config,
 568         }
 569     }
 570 }
 571
 572 impl<'a> Rewrite for [ast::Attribute] {
 573     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 574         let mut result = String::new();
 575         if self.is_empty() {
 576             return Some(result);
 577         }
 578         let indent = shape.indent.to_string(context.config);
 579
 580         for (i, a) in self.iter().enumerate() {
 581             let mut a_str = context.snippet(a.span);
 582
 583             // Write comments and blank lines between attributes.
 584             if i > 0 {
 585                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 586                 // This particular horror show is to preserve line breaks in between doc
 587                 // comments. An alternative would be to force such line breaks to start
 588                 // with the usual doc comment token.
 589                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 590                 let comment = comment.trim();
 591                 if !comment.is_empty() {
 592                     let comment = try_opt!(rewrite_comment(comment,
 593                                                            false,
 594                                                            Shape::legacy(context.config
 595                                                                              .ideal_width -
 596                                                                          shape.indent.width(),
 597                                                                          shape.indent),
 598                                                            context.config));
 599                     result.push_str(&indent);
 600                     result.push_str(&comment);
 601                     result.push('\n');
 602                 } else if multi_line {
 603                     result.push('\n');
 604                 }
 605                 result.push_str(&indent);
 606             }
 607
 608             if a_str.starts_with("//") {
 609                 a_str = try_opt!(rewrite_comment(&a_str,
 610                                                  false,
 611                                                  Shape::legacy(context.config.ideal_width -
 612                                                                shape.indent.width(),
 613                                                                shape.indent),
 614                                                  context.config));
 615             }
 616
 617             // Write the attribute itself.
 618             result.push_str(&a_str);
 619
 620             if i < self.len() - 1 {
 621                 result.push('\n');
 622             }
 623         }
 624
 625         Some(result)
 626     }
 627 }