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, 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::{self, CodeMapSpanUtils};
  19 use config::Config;
  20 use rewrite::{Rewrite, RewriteContext};
  21 use comment::rewrite_comment;
  22 use macros::rewrite_macro;
  23 use items::{rewrite_static, rewrite_associated_type, rewrite_type_alias, format_impl, format_trait};
  24
  25 // For format_missing and last_pos, need to use the source callsite (if applicable).
  26 // Required as generated code spans aren't guaranteed to follow on from the last span.
  27 macro_rules! source {
  28     ($this:ident, $sp: expr) => {
  29         $this.codemap.source_callsite($sp)
  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         match stmt.node {
  46             ast::StmtKind::Decl(ref decl, _) => {
  47                 if let ast::DeclKind::Item(ref item) = decl.node {
  48                     self.visit_item(item);
  49                 } else {
  50                     let rewrite = stmt.rewrite(&self.get_context(),
  51                                                self.config.max_width - self.block_indent.width(),
  52                                                self.block_indent);
  53
  54                     self.push_rewrite(stmt.span, rewrite);
  55                 }
  56             }
  57             ast::StmtKind::Expr(..) |
  58             ast::StmtKind::Semi(..) => {
  59                 let rewrite = stmt.rewrite(&self.get_context(),
  60                                            self.config.max_width - self.block_indent.width(),
  61                                            self.block_indent);
  62
  63                 self.push_rewrite(stmt.span, rewrite);
  64             }
  65             ast::StmtKind::Mac(ref mac, _macro_style, _) => {
  66                 self.format_missing_with_indent(source!(self, stmt.span).lo);
  67                 self.visit_mac(mac, None);
  68             }
  69         }
  70     }
  71
  72     pub fn visit_block(&mut self, b: &ast::Block) {
  73         debug!("visit_block: {:?} {:?}",
  74                self.codemap.lookup_char_pos(b.span.lo),
  75                self.codemap.lookup_char_pos(b.span.hi));
  76
  77         // Check if this block has braces.
  78         let snippet = self.snippet(b.span);
  79         let has_braces = snippet.starts_with("{") || snippet.starts_with("unsafe");
  80         let brace_compensation = if has_braces {
  81             BytePos(1)
  82         } else {
  83             BytePos(0)
  84         };
  85
  86         self.last_pos = self.last_pos + brace_compensation;
  87         self.block_indent = self.block_indent.block_indent(self.config);
  88         self.buffer.push_str("{");
  89
  90         for stmt in &b.stmts {
  91             self.visit_stmt(&stmt)
  92         }
  93
  94         if let Some(ref e) = b.expr {
  95             self.format_missing_with_indent(source!(self, e.span).lo);
  96             let rewrite = e.rewrite(&self.get_context(),
  97                          self.config.max_width - self.block_indent.width(),
  98                          self.block_indent)
  99                 .unwrap_or_else(|| self.snippet(e.span));
 100
 101             self.buffer.push_str(&rewrite);
 102             self.last_pos = source!(self, e.span).hi;
 103
 104             if utils::semicolon_for_expr(e) {
 105                 self.buffer.push_str(";");
 106             }
 107         }
 108
 109         // FIXME: we should compress any newlines here to just one
 110         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation);
 111         self.close_block();
 112         self.last_pos = source!(self, b.span).hi;
 113     }
 114
 115     // FIXME: this is a terrible hack to indent the comments between the last
 116     // item in the block and the closing brace to the block's level.
 117     // The closing brace itself, however, should be indented at a shallower
 118     // level.
 119     fn close_block(&mut self) {
 120         let total_len = self.buffer.len;
 121         let chars_too_many = if self.config.hard_tabs {
 122             1
 123         } else {
 124             self.config.tab_spaces
 125         };
 126         self.buffer.truncate(total_len - chars_too_many);
 127         self.buffer.push_str("}");
 128         self.block_indent = self.block_indent.block_unindent(self.config);
 129     }
 130
 131     // Note that this only gets called for function definitions. Required methods
 132     // on traits do not get handled here.
 133     fn visit_fn(&mut self,
 134                 fk: visit::FnKind,
 135                 fd: &ast::FnDecl,
 136                 b: &ast::Block,
 137                 s: Span,
 138                 _: ast::NodeId) {
 139         let indent = self.block_indent;
 140         let rewrite = match fk {
 141             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 142                 self.rewrite_fn(indent,
 143                                 ident,
 144                                 fd,
 145                                 generics,
 146                                 unsafety,
 147                                 constness,
 148                                 abi,
 149                                 vis,
 150                                 codemap::mk_sp(s.lo, b.span.lo),
 151                                 &b)
 152             }
 153             visit::FnKind::Method(ident, ref sig, vis) => {
 154                 self.rewrite_fn(indent,
 155                                 ident,
 156                                 fd,
 157                                 &sig.generics,
 158                                 sig.unsafety,
 159                                 sig.constness,
 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 => None,
 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, b.span).hi;
 174                     return;
 175                 }
 176             }
 177         } else {
 178             self.format_missing(source!(self, b.span).lo);
 179         }
 180
 181         self.last_pos = source!(self, b.span).lo;
 182         self.visit_block(b)
 183     }
 184
 185     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 seperate 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| {
 271                             match *def {
 272                                 ast::VariantData::Tuple(..) => s + ";",
 273                                 _ => s,
 274                             }
 275                         })
 276                 };
 277                 self.push_rewrite(item.span, rewrite);
 278             }
 279             ast::ItemKind::Enum(ref def, ref generics) => {
 280                 self.format_missing_with_indent(source!(self, item.span).lo);
 281                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 282                 self.last_pos = source!(self, item.span).hi;
 283             }
 284             ast::ItemKind::Mod(ref module) => {
 285                 self.format_missing_with_indent(source!(self, item.span).lo);
 286                 self.format_mod(module, &item.vis, item.span, item.ident);
 287             }
 288             ast::ItemKind::Mac(ref mac) => {
 289                 self.format_missing_with_indent(source!(self, item.span).lo);
 290                 self.visit_mac(mac, Some(item.ident));
 291             }
 292             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 293                 self.format_missing_with_indent(source!(self, item.span).lo);
 294                 self.format_foreign_mod(foreign_mod, item.span);
 295             }
 296             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 297                 let rewrite = rewrite_static("static",
 298                                              &item.vis,
 299                                              item.ident,
 300                                              ty,
 301                                              mutability,
 302                                              Some(expr),
 303                                              &self.get_context());
 304                 self.push_rewrite(item.span, rewrite);
 305             }
 306             ast::ItemKind::Const(ref ty, ref expr) => {
 307                 let rewrite = rewrite_static("const",
 308                                              &item.vis,
 309                                              item.ident,
 310                                              ty,
 311                                              ast::Mutability::Immutable,
 312                                              Some(expr),
 313                                              &self.get_context());
 314                 self.push_rewrite(item.span, rewrite);
 315             }
 316             ast::ItemKind::DefaultImpl(..) => {
 317                 // FIXME(#78): format impl definitions.
 318             }
 319             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 320                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 321                                                     generics,
 322                                                     unsafety,
 323                                                     constness,
 324                                                     abi,
 325                                                     &item.vis),
 326                               decl,
 327                               body,
 328                               item.span,
 329                               item.id)
 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         }
 342     }
 343
 344     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 345         if self.visit_attrs(&ti.attrs) {
 346             return;
 347         }
 348
 349         match ti.node {
 350             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 351                 let rewrite = rewrite_static("const",
 352                                              &ast::Visibility::Inherited,
 353                                              ti.ident,
 354                                              ty,
 355                                              ast::Mutability::Immutable,
 356                                              expr_opt.as_ref(),
 357                                              &self.get_context());
 358                 self.push_rewrite(ti.span, rewrite);
 359             }
 360             ast::TraitItemKind::Method(ref sig, None) => {
 361                 let indent = self.block_indent;
 362                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 363                 self.push_rewrite(ti.span, rewrite);
 364             }
 365             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 366                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 367                               &sig.decl,
 368                               &body,
 369                               ti.span,
 370                               ti.id);
 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         }
 381     }
 382
 383     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 384         if self.visit_attrs(&ii.attrs) {
 385             return;
 386         }
 387
 388         match ii.node {
 389             ast::ImplItemKind::Method(ref sig, ref body) => {
 390                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis)),
 391                               &sig.decl,
 392                               body,
 393                               ii.span,
 394                               ii.id);
 395             }
 396             ast::ImplItemKind::Const(ref ty, ref expr) => {
 397                 let rewrite = rewrite_static("const",
 398                                              &ii.vis,
 399                                              ii.ident,
 400                                              ty,
 401                                              ast::Mutability::Immutable,
 402                                              Some(expr),
 403                                              &self.get_context());
 404                 self.push_rewrite(ii.span, rewrite);
 405             }
 406             ast::ImplItemKind::Type(ref ty) => {
 407                 let rewrite = rewrite_associated_type(ii.ident,
 408                                                       Some(ty),
 409                                                       None,
 410                                                       &self.get_context(),
 411                                                       self.block_indent);
 412                 self.push_rewrite(ii.span, rewrite);
 413             }
 414             ast::ImplItemKind::Macro(ref mac) => {
 415                 self.format_missing_with_indent(source!(self, ii.span).lo);
 416                 self.visit_mac(mac, Some(ii.ident));
 417             }
 418         }
 419     }
 420
 421     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>) {
 422         // 1 = ;
 423         let width = self.config.max_width - self.block_indent.width() - 1;
 424         let rewrite = rewrite_macro(mac, ident, &self.get_context(), width, self.block_indent);
 425
 426         if let Some(res) = rewrite {
 427             self.buffer.push_str(&res);
 428             self.last_pos = source!(self, mac.span).hi;
 429         }
 430     }
 431
 432     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 433         self.format_missing_with_indent(source!(self, span).lo);
 434         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 435         self.buffer.push_str(&result);
 436         self.last_pos = source!(self, span).hi;
 437     }
 438
 439     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 440         FmtVisitor {
 441             parse_session: parse_session,
 442             codemap: parse_session.codemap(),
 443             buffer: StringBuffer::new(),
 444             last_pos: BytePos(0),
 445             block_indent: Indent {
 446                 block_indent: 0,
 447                 alignment: 0,
 448             },
 449             config: config,
 450         }
 451     }
 452
 453     pub fn snippet(&self, span: Span) -> String {
 454         match self.codemap.span_to_snippet(span) {
 455             Ok(s) => s,
 456             Err(_) => {
 457                 println!("Couldn't make snippet for span {:?}->{:?}",
 458                          self.codemap.lookup_char_pos(span.lo),
 459                          self.codemap.lookup_char_pos(span.hi));
 460                 "".to_owned()
 461             }
 462         }
 463     }
 464
 465     // Returns true if we should skip the following item.
 466     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 467         if utils::contains_skip(attrs) {
 468             return true;
 469         }
 470
 471         let outers: Vec<_> = attrs.iter()
 472             .filter(|a| a.node.style == ast::AttrStyle::Outer)
 473             .cloned()
 474             .collect();
 475         if outers.is_empty() {
 476             return false;
 477         }
 478
 479         let first = &outers[0];
 480         self.format_missing_with_indent(source!(self, first.span).lo);
 481
 482         let rewrite = outers.rewrite(&self.get_context(),
 483                      self.config.max_width - self.block_indent.width(),
 484                      self.block_indent)
 485             .unwrap();
 486         self.buffer.push_str(&rewrite);
 487         let last = outers.last().unwrap();
 488         self.last_pos = source!(self, last.span).hi;
 489         false
 490     }
 491
 492     fn walk_mod_items(&mut self, m: &ast::Mod) {
 493         for item in &m.items {
 494             self.visit_item(&item);
 495         }
 496     }
 497
 498     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 499         // Decide whether this is an inline mod or an external mod.
 500         let local_file_name = self.codemap.span_to_filename(s);
 501         let is_internal = local_file_name == self.codemap.span_to_filename(source!(self, m.inner));
 502
 503         self.buffer.push_str(&*utils::format_visibility(vis));
 504         self.buffer.push_str("mod ");
 505         self.buffer.push_str(&ident.to_string());
 506
 507         if is_internal {
 508             self.buffer.push_str(" {");
 509             // Hackery to account for the closing }.
 510             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 511             let body_snippet =
 512                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 513             let body_snippet = body_snippet.trim();
 514             if body_snippet.is_empty() {
 515                 self.buffer.push_str("}");
 516             } else {
 517                 self.last_pos = mod_lo;
 518                 self.block_indent = self.block_indent.block_indent(self.config);
 519                 self.walk_mod_items(m);
 520                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 521                 self.close_block();
 522             }
 523             self.last_pos = source!(self, m.inner).hi;
 524         } else {
 525             self.buffer.push_str(";");
 526             self.last_pos = source!(self, s).hi;
 527         }
 528     }
 529
 530     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 531         let filemap = self.codemap.lookup_char_pos(source!(self, m.inner).lo).file;
 532         self.last_pos = filemap.start_pos;
 533         self.block_indent = Indent::empty();
 534         self.walk_mod_items(m);
 535         self.format_missing(filemap.end_pos);
 536     }
 537
 538     fn format_import(&mut self, vis: &ast::Visibility, vp: &ast::ViewPath, span: Span) {
 539         let vis = utils::format_visibility(vis);
 540         let mut offset = self.block_indent;
 541         offset.alignment += vis.len() + "use ".len();
 542         // 1 = ";"
 543         match vp.rewrite(&self.get_context(),
 544                          self.config.max_width - offset.width() - 1,
 545                          offset) {
 546             Some(ref s) if s.is_empty() => {
 547                 // Format up to last newline
 548                 let prev_span = codemap::mk_sp(self.last_pos, source!(self, span).lo);
 549                 let span_end = match self.snippet(prev_span).rfind('\n') {
 550                     Some(offset) => self.last_pos + BytePos(offset as u32),
 551                     None => source!(self, span).lo,
 552                 };
 553                 self.format_missing(span_end);
 554                 self.last_pos = source!(self, span).hi;
 555             }
 556             Some(ref s) => {
 557                 let s = format!("{}use {};", vis, s);
 558                 self.format_missing_with_indent(source!(self, span).lo);
 559                 self.buffer.push_str(&s);
 560                 self.last_pos = source!(self, span).hi;
 561             }
 562             None => {
 563                 self.format_missing_with_indent(source!(self, span).lo);
 564                 self.format_missing(source!(self, span).hi);
 565             }
 566         }
 567     }
 568
 569     pub fn get_context(&self) -> RewriteContext {
 570         RewriteContext {
 571             parse_session: self.parse_session,
 572             codemap: self.codemap,
 573             config: self.config,
 574             block_indent: self.block_indent,
 575         }
 576     }
 577 }
 578
 579 impl<'a> Rewrite for [ast::Attribute] {
 580     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 581         let mut result = String::new();
 582         if self.is_empty() {
 583             return Some(result);
 584         }
 585         let indent = offset.to_string(context.config);
 586
 587         for (i, a) in self.iter().enumerate() {
 588             let mut a_str = context.snippet(a.span);
 589
 590             // Write comments and blank lines between attributes.
 591             if i > 0 {
 592                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 593                 // This particular horror show is to preserve line breaks in between doc
 594                 // comments. An alternative would be to force such line breaks to start
 595                 // with the usual doc comment token.
 596                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 597                 let comment = comment.trim();
 598                 if !comment.is_empty() {
 599                     let comment = try_opt!(rewrite_comment(comment,
 600                                                            false,
 601                                                            context.config.ideal_width -
 602                                                            offset.width(),
 603                                                            offset,
 604                                                            context.config));
 605                     result.push_str(&indent);
 606                     result.push_str(&comment);
 607                     result.push('\n');
 608                 } else if multi_line {
 609                     result.push('\n');
 610                 }
 611                 result.push_str(&indent);
 612             }
 613
 614             if a_str.starts_with("//") {
 615                 a_str = try_opt!(rewrite_comment(&a_str,
 616                                                  false,
 617                                                  context.config.ideal_width - offset.width(),
 618                                                  offset,
 619                                                  context.config));
 620             }
 621
 622             // Write the attribute itself.
 623             result.push_str(&a_str);
 624
 625             if i < self.len() - 1 {
 626                 result.push('\n');
 627             }
 628         }
 629
 630         Some(result)
 631     }
 632 }