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, 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                                            self.config.max_width - self.block_indent.width(),
  63                                            self.block_indent);
  64                 self.push_rewrite(stmt.span, rewrite);
  65             }
  66             ast::StmtKind::Mac(ref mac) => {
  67                 let (ref mac, _macro_style, _) = **mac;
  68                 self.visit_mac(mac, None, MacroPosition::Statement);
  69                 self.format_missing(stmt.span.hi);
  70             }
  71         }
  72     }
  73
  74     pub fn visit_block(&mut self, b: &ast::Block) {
  75         debug!("visit_block: {:?} {:?}",
  76                self.codemap.lookup_char_pos(b.span.lo),
  77                self.codemap.lookup_char_pos(b.span.hi));
  78
  79         // Check if this block has braces.
  80         let snippet = self.snippet(b.span);
  81         let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
  82         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
  83
  84         self.last_pos = self.last_pos + brace_compensation;
  85         self.block_indent = self.block_indent.block_indent(self.config);
  86         self.buffer.push_str("{");
  87
  88         for stmt in &b.stmts {
  89             self.visit_stmt(stmt)
  90         }
  91
  92         if !b.stmts.is_empty() {
  93             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
  94                 if utils::semicolon_for_expr(expr) {
  95                     self.buffer.push_str(";");
  96                 }
  97             }
  98         }
  99
 100         // FIXME: we should compress any newlines here to just one
 101         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation);
 102         self.close_block();
 103         self.last_pos = source!(self, b.span).hi;
 104     }
 105
 106     // FIXME: this is a terrible hack to indent the comments between the last
 107     // item in the block and the closing brace to the block's level.
 108     // The closing brace itself, however, should be indented at a shallower
 109     // level.
 110     fn close_block(&mut self) {
 111         let total_len = self.buffer.len;
 112         let chars_too_many = if self.config.hard_tabs {
 113             1
 114         } else {
 115             self.config.tab_spaces
 116         };
 117         self.buffer.truncate(total_len - chars_too_many);
 118         self.buffer.push_str("}");
 119         self.block_indent = self.block_indent.block_unindent(self.config);
 120     }
 121
 122     // Note that this only gets called for function definitions. Required methods
 123     // on traits do not get handled here.
 124     fn visit_fn(&mut self,
 125                 fk: visit::FnKind,
 126                 fd: &ast::FnDecl,
 127                 s: Span,
 128                 _: ast::NodeId,
 129                 defaultness: ast::Defaultness) {
 130         let indent = self.block_indent;
 131         let block;
 132         let rewrite = match fk {
 133             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 134                 block = b;
 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, b) => {
 148                 block = b;
 149                 self.rewrite_fn(indent,
 150                                 ident,
 151                                 fd,
 152                                 &sig.generics,
 153                                 sig.unsafety,
 154                                 sig.constness.node,
 155                                 defaultness,
 156                                 sig.abi,
 157                                 vis.unwrap_or(&ast::Visibility::Inherited),
 158                                 codemap::mk_sp(s.lo, b.span.lo),
 159                                 &b)
 160             }
 161             visit::FnKind::Closure(_) => unreachable!(),
 162         };
 163
 164         if let Some(fn_str) = rewrite {
 165             self.format_missing_with_indent(source!(self, s).lo);
 166             self.buffer.push_str(&fn_str);
 167             if let Some(c) = fn_str.chars().last() {
 168                 if c == '}' {
 169                     self.last_pos = source!(self, block.span).hi;
 170                     return;
 171                 }
 172             }
 173         } else {
 174             self.format_missing(source!(self, block.span).lo);
 175         }
 176
 177         self.last_pos = source!(self, block.span).lo;
 178         self.visit_block(block)
 179     }
 180
 181     pub fn visit_item(&mut self, item: &ast::Item) {
 182         // This is where we bail out if there is a skip attribute. This is only
 183         // complex in the module case. It is complex because the module could be
 184         // in a separate file and there might be attributes in both files, but
 185         // the AST lumps them all together.
 186         match item.node {
 187             ast::ItemKind::Mod(ref m) => {
 188                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 189                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 190                 if outer_file.name == inner_file.name {
 191                     // Module is inline, in this case we treat modules like any
 192                     // other item.
 193                     if self.visit_attrs(&item.attrs) {
 194                         self.push_rewrite(item.span, None);
 195                         return;
 196                     }
 197                 } else if utils::contains_skip(&item.attrs) {
 198                     // Module is not inline, but should be skipped.
 199                     return;
 200                 } else {
 201                     // Module is not inline and should not be skipped. We want
 202                     // to process only the attributes in the current file.
 203                     let attrs = item.attrs
 204                         .iter()
 205                         .filter_map(|a| {
 206                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 207                             if attr_file.name == outer_file.name {
 208                                 Some(a.clone())
 209                             } else {
 210                                 None
 211                             }
 212                         })
 213                         .collect::<Vec<_>>();
 214                     // Assert because if we should skip it should be caught by
 215                     // the above case.
 216                     assert!(!self.visit_attrs(&attrs));
 217                 }
 218             }
 219             _ => {
 220                 if self.visit_attrs(&item.attrs) {
 221                     self.push_rewrite(item.span, None);
 222                     return;
 223                 }
 224             }
 225         }
 226
 227         match item.node {
 228             ast::ItemKind::Use(ref vp) => {
 229                 self.format_import(&item.vis, vp, item.span);
 230             }
 231             ast::ItemKind::Impl(..) => {
 232                 self.format_missing_with_indent(source!(self, item.span).lo);
 233                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 234                     self.buffer.push_str(&impl_str);
 235                     self.last_pos = source!(self, item.span).hi;
 236                 }
 237             }
 238             ast::ItemKind::Trait(..) => {
 239                 self.format_missing_with_indent(item.span.lo);
 240                 if let Some(trait_str) = format_trait(&self.get_context(),
 241                                                       item,
 242                                                       self.block_indent) {
 243                     self.buffer.push_str(&trait_str);
 244                     self.last_pos = source!(self, item.span).hi;
 245                 }
 246             }
 247             ast::ItemKind::ExternCrate(_) => {
 248                 self.format_missing_with_indent(source!(self, item.span).lo);
 249                 let new_str = self.snippet(item.span);
 250                 self.buffer.push_str(&new_str);
 251                 self.last_pos = source!(self, item.span).hi;
 252             }
 253             ast::ItemKind::Struct(ref def, ref generics) => {
 254                 let rewrite = {
 255                     let indent = self.block_indent;
 256                     let context = self.get_context();
 257                     ::items::format_struct(&context,
 258                                            "struct ",
 259                                            item.ident,
 260                                            &item.vis,
 261                                            def,
 262                                            Some(generics),
 263                                            item.span,
 264                                            indent,
 265                                            None)
 266                         .map(|s| match *def {
 267                             ast::VariantData::Tuple(..) => s + ";",
 268                             _ => s,
 269                         })
 270                 };
 271                 self.push_rewrite(item.span, rewrite);
 272             }
 273             ast::ItemKind::Enum(ref def, ref generics) => {
 274                 self.format_missing_with_indent(source!(self, item.span).lo);
 275                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 276                 self.last_pos = source!(self, item.span).hi;
 277             }
 278             ast::ItemKind::Mod(ref module) => {
 279                 self.format_missing_with_indent(source!(self, item.span).lo);
 280                 self.format_mod(module, &item.vis, item.span, item.ident);
 281             }
 282             ast::ItemKind::Mac(ref mac) => {
 283                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 284             }
 285             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 286                 self.format_missing_with_indent(source!(self, item.span).lo);
 287                 self.format_foreign_mod(foreign_mod, item.span);
 288             }
 289             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 290                 let rewrite = rewrite_static("static",
 291                                              &item.vis,
 292                                              item.ident,
 293                                              ty,
 294                                              mutability,
 295                                              Some(expr),
 296                                              &self.get_context());
 297                 self.push_rewrite(item.span, rewrite);
 298             }
 299             ast::ItemKind::Const(ref ty, ref expr) => {
 300                 let rewrite = rewrite_static("const",
 301                                              &item.vis,
 302                                              item.ident,
 303                                              ty,
 304                                              ast::Mutability::Immutable,
 305                                              Some(expr),
 306                                              &self.get_context());
 307                 self.push_rewrite(item.span, rewrite);
 308             }
 309             ast::ItemKind::DefaultImpl(..) => {
 310                 // FIXME(#78): format impl definitions.
 311             }
 312             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 313                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 314                                                     generics,
 315                                                     unsafety,
 316                                                     constness,
 317                                                     abi,
 318                                                     &item.vis,
 319                                                     body),
 320                               decl,
 321                               item.span,
 322                               item.id,
 323                               ast::Defaultness::Final)
 324             }
 325             ast::ItemKind::Ty(ref ty, ref generics) => {
 326                 let rewrite = rewrite_type_alias(&self.get_context(),
 327                                                  self.block_indent,
 328                                                  item.ident,
 329                                                  ty,
 330                                                  generics,
 331                                                  &item.vis,
 332                                                  item.span);
 333                 self.push_rewrite(item.span, rewrite);
 334             }
 335             ast::ItemKind::Union(..) => {
 336                 // FIXME(#1157): format union definitions.
 337             }
 338         }
 339     }
 340
 341     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 342         if self.visit_attrs(&ti.attrs) {
 343             self.push_rewrite(ti.span, None);
 344             return;
 345         }
 346
 347         match ti.node {
 348             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 349                 let rewrite = rewrite_static("const",
 350                                              &ast::Visibility::Inherited,
 351                                              ti.ident,
 352                                              ty,
 353                                              ast::Mutability::Immutable,
 354                                              expr_opt.as_ref(),
 355                                              &self.get_context());
 356                 self.push_rewrite(ti.span, rewrite);
 357             }
 358             ast::TraitItemKind::Method(ref sig, None) => {
 359                 let indent = self.block_indent;
 360                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 361                 self.push_rewrite(ti.span, rewrite);
 362             }
 363             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 364                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None, body),
 365                               &sig.decl,
 366                               ti.span,
 367                               ti.id,
 368                               ast::Defaultness::Final);
 369             }
 370             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 371                 let rewrite = rewrite_associated_type(ti.ident,
 372                                                       None,
 373                                                       Some(type_param_bounds),
 374                                                       &self.get_context(),
 375                                                       self.block_indent);
 376                 self.push_rewrite(ti.span, rewrite);
 377             }
 378             ast::TraitItemKind::Macro(..) => {
 379                 // FIXME(#1158) Macros in trait item position
 380             }
 381         }
 382     }
 383
 384     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 385         if self.visit_attrs(&ii.attrs) {
 386             self.push_rewrite(ii.span, None);
 387             return;
 388         }
 389
 390         match ii.node {
 391             ast::ImplItemKind::Method(ref sig, ref body) => {
 392                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 393                               &sig.decl,
 394                               ii.span,
 395                               ii.id,
 396                               ii.defaultness);
 397             }
 398             ast::ImplItemKind::Const(ref ty, ref expr) => {
 399                 let rewrite = rewrite_static("const",
 400                                              &ii.vis,
 401                                              ii.ident,
 402                                              ty,
 403                                              ast::Mutability::Immutable,
 404                                              Some(expr),
 405                                              &self.get_context());
 406                 self.push_rewrite(ii.span, rewrite);
 407             }
 408             ast::ImplItemKind::Type(ref ty) => {
 409                 let rewrite = rewrite_associated_type(ii.ident,
 410                                                       Some(ty),
 411                                                       None,
 412                                                       &self.get_context(),
 413                                                       self.block_indent);
 414                 self.push_rewrite(ii.span, rewrite);
 415             }
 416             ast::ImplItemKind::Macro(ref mac) => {
 417                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 418             }
 419         }
 420     }
 421
 422     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 423         // 1 = ;
 424         let width = self.config.max_width - self.block_indent.width() - 1;
 425         let rewrite = rewrite_macro(mac,
 426                                     ident,
 427                                     &self.get_context(),
 428                                     width,
 429                                     self.block_indent,
 430                                     pos);
 431         self.push_rewrite(mac.span, rewrite);
 432     }
 433
 434     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 435         self.format_missing_with_indent(source!(self, span).lo);
 436         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 437         self.buffer.push_str(&result);
 438         self.last_pos = source!(self, span).hi;
 439     }
 440
 441     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 442         FmtVisitor {
 443             parse_session: parse_session,
 444             codemap: parse_session.codemap(),
 445             buffer: StringBuffer::new(),
 446             last_pos: BytePos(0),
 447             block_indent: Indent {
 448                 block_indent: 0,
 449                 alignment: 0,
 450             },
 451             config: config,
 452         }
 453     }
 454
 455     pub fn snippet(&self, span: Span) -> String {
 456         match self.codemap.span_to_snippet(span) {
 457             Ok(s) => s,
 458             Err(_) => {
 459                 println!("Couldn't make snippet for span {:?}->{:?}",
 460                          self.codemap.lookup_char_pos(span.lo),
 461                          self.codemap.lookup_char_pos(span.hi));
 462                 "".to_owned()
 463             }
 464         }
 465     }
 466
 467     // Returns true if we should skip the following item.
 468     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 469         if utils::contains_skip(attrs) {
 470             return true;
 471         }
 472
 473         let outers: Vec<_> = attrs.iter()
 474             .filter(|a| a.style == ast::AttrStyle::Outer)
 475             .cloned()
 476             .collect();
 477         if outers.is_empty() {
 478             return false;
 479         }
 480
 481         let first = &outers[0];
 482         self.format_missing_with_indent(source!(self, first.span).lo);
 483
 484         let rewrite = outers.rewrite(&self.get_context(),
 485                      self.config.max_width - self.block_indent.width(),
 486                      self.block_indent)
 487             .unwrap();
 488         self.buffer.push_str(&rewrite);
 489         let last = outers.last().unwrap();
 490         self.last_pos = source!(self, last.span).hi;
 491         false
 492     }
 493
 494     fn walk_mod_items(&mut self, m: &ast::Mod) {
 495         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 496         while !items_left.is_empty() {
 497             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 498             // to be potentially reordered within `format_imports`. Otherwise, just format the
 499             // next item for output.
 500             if self.config.reorder_imports && is_use_item(&*items_left[0]) {
 501                 let use_item_length =
 502                     items_left.iter().take_while(|ppi| is_use_item(&***ppi)).count();
 503                 let (use_items, rest) = items_left.split_at(use_item_length);
 504                 self.format_imports(use_items);
 505                 items_left = rest;
 506             } else {
 507                 // `unwrap()` is safe here because we know `items_left`
 508                 // has elements from the loop condition
 509                 let (item, rest) = items_left.split_first().unwrap();
 510                 self.visit_item(item);
 511                 items_left = rest;
 512             }
 513         }
 514     }
 515
 516     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 517         // Decide whether this is an inline mod or an external mod.
 518         let local_file_name = self.codemap.span_to_filename(s);
 519         let inner_span = source!(self, m.inner);
 520         let is_internal = !(inner_span.lo.0 == 0 && inner_span.hi.0 == 0) &&
 521                           local_file_name == self.codemap.span_to_filename(inner_span);
 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(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 }