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                                 None,
 146                                 generics,
 147                                 unsafety,
 148                                 constness,
 149                                 abi,
 150                                 vis,
 151                                 codemap::mk_sp(s.lo, b.span.lo),
 152                                 &b)
 153             }
 154             visit::FnKind::Method(ident, ref sig, vis) => {
 155                 self.rewrite_fn(indent,
 156                                 ident,
 157                                 fd,
 158                                 Some(&sig.explicit_self),
 159                                 &sig.generics,
 160                                 sig.unsafety,
 161                                 sig.constness,
 162                                 sig.abi,
 163                                 vis.unwrap_or(&ast::Visibility::Inherited),
 164                                 codemap::mk_sp(s.lo, b.span.lo),
 165                                 &b)
 166             }
 167             visit::FnKind::Closure => None,
 168         };
 169
 170         if let Some(fn_str) = rewrite {
 171             self.format_missing_with_indent(source!(self, s).lo);
 172             self.buffer.push_str(&fn_str);
 173             if let Some(c) = fn_str.chars().last() {
 174                 if c == '}' {
 175                     self.last_pos = source!(self, b.span).hi;
 176                     return;
 177                 }
 178             }
 179         } else {
 180             self.format_missing(source!(self, b.span).lo);
 181         }
 182
 183         self.last_pos = source!(self, b.span).lo;
 184         self.visit_block(b)
 185     }
 186
 187     fn visit_item(&mut self, item: &ast::Item) {
 188         // This is where we bail out if there is a skip attribute. This is only
 189         // complex in the module case. It is complex because the module could be
 190         // in a seperate file and there might be attributes in both files, but
 191         // the AST lumps them all together.
 192         match item.node {
 193             ast::ItemKind::Mod(ref m) => {
 194                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 195                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 196                 if outer_file.name == inner_file.name {
 197                     // Module is inline, in this case we treat modules like any
 198                     // other item.
 199                     if self.visit_attrs(&item.attrs) {
 200                         self.push_rewrite(item.span, None);
 201                         return;
 202                     }
 203                 } else if utils::contains_skip(&item.attrs) {
 204                     // Module is not inline, but should be skipped.
 205                     return;
 206                 } else {
 207                     // Module is not inline and should not be skipped. We want
 208                     // to process only the attributes in the current file.
 209                     let attrs = item.attrs
 210                         .iter()
 211                         .filter_map(|a| {
 212                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 213                             if attr_file.name == outer_file.name {
 214                                 Some(a.clone())
 215                             } else {
 216                                 None
 217                             }
 218                         })
 219                         .collect::<Vec<_>>();
 220                     // Assert because if we should skip it should be caught by
 221                     // the above case.
 222                     assert!(!self.visit_attrs(&attrs));
 223                 }
 224             }
 225             _ => {
 226                 if self.visit_attrs(&item.attrs) {
 227                     self.push_rewrite(item.span, None);
 228                     return;
 229                 }
 230             }
 231         }
 232
 233         match item.node {
 234             ast::ItemKind::Use(ref vp) => {
 235                 self.format_import(&item.vis, vp, item.span);
 236             }
 237             ast::ItemKind::Impl(..) => {
 238                 self.format_missing_with_indent(source!(self, item.span).lo);
 239                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 240                     self.buffer.push_str(&impl_str);
 241                     self.last_pos = source!(self, item.span).hi;
 242                 }
 243             }
 244             ast::ItemKind::Trait(..) => {
 245                 self.format_missing_with_indent(item.span.lo);
 246                 if let Some(trait_str) = format_trait(&self.get_context(),
 247                                                       item,
 248                                                       self.block_indent) {
 249                     self.buffer.push_str(&trait_str);
 250                     self.last_pos = source!(self, item.span).hi;
 251                 }
 252             }
 253             ast::ItemKind::ExternCrate(_) => {
 254                 self.format_missing_with_indent(source!(self, item.span).lo);
 255                 let new_str = self.snippet(item.span);
 256                 self.buffer.push_str(&new_str);
 257                 self.last_pos = source!(self, item.span).hi;
 258             }
 259             ast::ItemKind::Struct(ref def, ref generics) => {
 260                 let rewrite = {
 261                     let indent = self.block_indent;
 262                     let context = self.get_context();
 263                     ::items::format_struct(&context,
 264                                            "struct ",
 265                                            item.ident,
 266                                            &item.vis,
 267                                            def,
 268                                            Some(generics),
 269                                            item.span,
 270                                            indent,
 271                                            None)
 272                         .map(|s| {
 273                             match *def {
 274                                 ast::VariantData::Tuple(..) => s + ";",
 275                                 _ => s,
 276                             }
 277                         })
 278                 };
 279                 self.push_rewrite(item.span, rewrite);
 280             }
 281             ast::ItemKind::Enum(ref def, ref generics) => {
 282                 self.format_missing_with_indent(source!(self, item.span).lo);
 283                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 284                 self.last_pos = source!(self, item.span).hi;
 285             }
 286             ast::ItemKind::Mod(ref module) => {
 287                 self.format_missing_with_indent(source!(self, item.span).lo);
 288                 self.format_mod(module, &item.vis, item.span, item.ident);
 289             }
 290             ast::ItemKind::Mac(ref mac) => {
 291                 self.format_missing_with_indent(source!(self, item.span).lo);
 292                 self.visit_mac(mac, Some(item.ident));
 293             }
 294             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 295                 self.format_missing_with_indent(source!(self, item.span).lo);
 296                 self.format_foreign_mod(foreign_mod, item.span);
 297             }
 298             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 299                 let rewrite = rewrite_static("static",
 300                                              &item.vis,
 301                                              item.ident,
 302                                              ty,
 303                                              mutability,
 304                                              Some(expr),
 305                                              &self.get_context());
 306                 self.push_rewrite(item.span, rewrite);
 307             }
 308             ast::ItemKind::Const(ref ty, ref expr) => {
 309                 let rewrite = rewrite_static("const",
 310                                              &item.vis,
 311                                              item.ident,
 312                                              ty,
 313                                              ast::Mutability::Immutable,
 314                                              Some(expr),
 315                                              &self.get_context());
 316                 self.push_rewrite(item.span, rewrite);
 317             }
 318             ast::ItemKind::DefaultImpl(..) => {
 319                 // FIXME(#78): format impl definitions.
 320             }
 321             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 322                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 323                                                     generics,
 324                                                     unsafety,
 325                                                     constness,
 326                                                     abi,
 327                                                     &item.vis),
 328                               decl,
 329                               body,
 330                               item.span,
 331                               item.id)
 332             }
 333             ast::ItemKind::Ty(ref ty, ref generics) => {
 334                 let rewrite = rewrite_type_alias(&self.get_context(),
 335                                                  self.block_indent,
 336                                                  item.ident,
 337                                                  ty,
 338                                                  generics,
 339                                                  &item.vis,
 340                                                  item.span);
 341                 self.push_rewrite(item.span, rewrite);
 342             }
 343         }
 344     }
 345
 346     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 347         if self.visit_attrs(&ti.attrs) {
 348             return;
 349         }
 350
 351         match ti.node {
 352             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 353                 let rewrite = rewrite_static("const",
 354                                              &ast::Visibility::Inherited,
 355                                              ti.ident,
 356                                              ty,
 357                                              ast::Mutability::Immutable,
 358                                              expr_opt.as_ref(),
 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),
 369                               &sig.decl,
 370                               &body,
 371                               ti.span,
 372                               ti.id);
 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         }
 383     }
 384
 385     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 386         if self.visit_attrs(&ii.attrs) {
 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)),
 393                               &sig.decl,
 394                               body,
 395                               ii.span,
 396                               ii.id);
 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.format_missing_with_indent(source!(self, ii.span).lo);
 418                 self.visit_mac(mac, Some(ii.ident));
 419             }
 420         }
 421     }
 422
 423     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>) {
 424         // 1 = ;
 425         let width = self.config.max_width - self.block_indent.width() - 1;
 426         let rewrite = rewrite_macro(mac, ident, &self.get_context(), width, self.block_indent);
 427
 428         if let Some(res) = rewrite {
 429             self.buffer.push_str(&res);
 430             self.last_pos = source!(self, mac.span).hi;
 431         }
 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.node.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         for item in &m.items {
 496             self.visit_item(&item);
 497         }
 498     }
 499
 500     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 501         // Decide whether this is an inline mod or an external mod.
 502         let local_file_name = self.codemap.span_to_filename(s);
 503         let is_internal = local_file_name == self.codemap.span_to_filename(source!(self, m.inner));
 504
 505         self.buffer.push_str(&*utils::format_visibility(vis));
 506         self.buffer.push_str("mod ");
 507         self.buffer.push_str(&ident.to_string());
 508
 509         if is_internal {
 510             self.buffer.push_str(" {");
 511             // Hackery to account for the closing }.
 512             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 513             let body_snippet =
 514                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 515             let body_snippet = body_snippet.trim();
 516             if body_snippet.is_empty() {
 517                 self.buffer.push_str("}");
 518             } else {
 519                 self.last_pos = mod_lo;
 520                 self.block_indent = self.block_indent.block_indent(self.config);
 521                 self.walk_mod_items(m);
 522                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 523                 self.close_block();
 524             }
 525             self.last_pos = source!(self, m.inner).hi;
 526         } else {
 527             self.buffer.push_str(";");
 528             self.last_pos = source!(self, s).hi;
 529         }
 530     }
 531
 532     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 533         let filemap = self.codemap.lookup_char_pos(source!(self, m.inner).lo).file;
 534         self.last_pos = filemap.start_pos;
 535         self.block_indent = Indent::empty();
 536         self.walk_mod_items(m);
 537         self.format_missing(filemap.end_pos);
 538     }
 539
 540     fn format_import(&mut self, vis: &ast::Visibility, vp: &ast::ViewPath, span: Span) {
 541         let vis = utils::format_visibility(vis);
 542         let mut offset = self.block_indent;
 543         offset.alignment += vis.len() + "use ".len();
 544         // 1 = ";"
 545         match vp.rewrite(&self.get_context(),
 546                          self.config.max_width - offset.width() - 1,
 547                          offset) {
 548             Some(ref s) if s.is_empty() => {
 549                 // Format up to last newline
 550                 let prev_span = codemap::mk_sp(self.last_pos, source!(self, span).lo);
 551                 let span_end = match self.snippet(prev_span).rfind('\n') {
 552                     Some(offset) => self.last_pos + BytePos(offset as u32),
 553                     None => source!(self, span).lo,
 554                 };
 555                 self.format_missing(span_end);
 556                 self.last_pos = source!(self, span).hi;
 557             }
 558             Some(ref s) => {
 559                 let s = format!("{}use {};", vis, s);
 560                 self.format_missing_with_indent(source!(self, span).lo);
 561                 self.buffer.push_str(&s);
 562                 self.last_pos = source!(self, span).hi;
 563             }
 564             None => {
 565                 self.format_missing_with_indent(source!(self, span).lo);
 566                 self.format_missing(source!(self, span).hi);
 567             }
 568         }
 569     }
 570
 571     pub fn get_context(&self) -> RewriteContext {
 572         RewriteContext {
 573             parse_session: self.parse_session,
 574             codemap: self.codemap,
 575             config: self.config,
 576             block_indent: self.block_indent,
 577         }
 578     }
 579 }
 580
 581 impl<'a> Rewrite for [ast::Attribute] {
 582     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 583         let mut result = String::new();
 584         if self.is_empty() {
 585             return Some(result);
 586         }
 587         let indent = offset.to_string(context.config);
 588
 589         for (i, a) in self.iter().enumerate() {
 590             let mut a_str = context.snippet(a.span);
 591
 592             // Write comments and blank lines between attributes.
 593             if i > 0 {
 594                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 595                 // This particular horror show is to preserve line breaks in between doc
 596                 // comments. An alternative would be to force such line breaks to start
 597                 // with the usual doc comment token.
 598                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 599                 let comment = comment.trim();
 600                 if !comment.is_empty() {
 601                     let comment = try_opt!(rewrite_comment(comment,
 602                                                            false,
 603                                                            context.config.ideal_width -
 604                                                            offset.width(),
 605                                                            offset,
 606                                                            context.config));
 607                     result.push_str(&indent);
 608                     result.push_str(&comment);
 609                     result.push('\n');
 610                 } else if multi_line {
 611                     result.push('\n');
 612                 }
 613                 result.push_str(&indent);
 614             }
 615
 616             if a_str.starts_with("//") {
 617                 a_str = try_opt!(rewrite_comment(&a_str,
 618                                                  false,
 619                                                  context.config.ideal_width - offset.width(),
 620                                                  offset,
 621                                                  context.config));
 622             }
 623
 624             // Write the attribute itself.
 625             result.push_str(&a_str);
 626
 627             if i < self.len() - 1 {
 628                 result.push('\n');
 629             }
 630         }
 631
 632         Some(result)
 633     }
 634 }