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;
  12 use syntax::codemap::{self, CodeMap, Span, BytePos};
  13 use syntax::parse::ParseSess;
  14 use syntax::visit;
  15
  16 use strings::string_buffer::StringBuffer;
  17
  18 use Indent;
  19 use utils;
  20 use config::Config;
  21 use rewrite::{Rewrite, RewriteContext};
  22 use comment::rewrite_comment;
  23 use macros::rewrite_macro;
  24 use items::{rewrite_static, rewrite_associated_static, rewrite_associated_type,
  25             rewrite_type_alias, format_impl, format_trait};
  26
  27 pub struct FmtVisitor<'a> {
  28     pub parse_session: &'a ParseSess,
  29     pub codemap: &'a CodeMap,
  30     pub buffer: StringBuffer,
  31     pub last_pos: BytePos,
  32     // FIXME: use an RAII util or closure for indenting
  33     pub block_indent: Indent,
  34     pub config: &'a Config,
  35 }
  36
  37 impl<'a> FmtVisitor<'a> {
  38     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  39         match stmt.node {
  40             ast::StmtKind::Decl(ref decl, _) => {
  41                 if let ast::DeclKind::Item(ref item) = decl.node {
  42                     self.visit_item(item);
  43                 } else {
  44                     let rewrite = stmt.rewrite(&self.get_context(),
  45                                                self.config.max_width - self.block_indent.width(),
  46                                                self.block_indent);
  47
  48                     self.push_rewrite(stmt.span, rewrite);
  49                 }
  50             }
  51             ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
  52                 let rewrite = stmt.rewrite(&self.get_context(),
  53                                            self.config.max_width - self.block_indent.width(),
  54                                            self.block_indent);
  55
  56                 self.push_rewrite(stmt.span, rewrite);
  57             }
  58             ast::StmtKind::Mac(ref mac, _macro_style, _) => {
  59                 self.format_missing_with_indent(stmt.span.lo);
  60                 self.visit_mac(mac);
  61             }
  62         }
  63     }
  64
  65     pub fn visit_block(&mut self, b: &ast::Block) {
  66         debug!("visit_block: {:?} {:?}",
  67                self.codemap.lookup_char_pos(b.span.lo),
  68                self.codemap.lookup_char_pos(b.span.hi));
  69
  70         // Check if this block has braces.
  71         let snippet = self.snippet(b.span);
  72         let has_braces = snippet.starts_with("{") || snippet.starts_with("unsafe");
  73         let brace_compensation = if has_braces {
  74             BytePos(1)
  75         } else {
  76             BytePos(0)
  77         };
  78
  79         self.last_pos = self.last_pos + brace_compensation;
  80         self.block_indent = self.block_indent.block_indent(self.config);
  81         self.buffer.push_str("{");
  82
  83         for stmt in &b.stmts {
  84             self.visit_stmt(&stmt)
  85         }
  86
  87         if let Some(ref e) = b.expr {
  88             self.format_missing_with_indent(e.span.lo);
  89             let rewrite = e.rewrite(&self.get_context(),
  90                                     self.config.max_width - self.block_indent.width(),
  91                                     self.block_indent)
  92                            .unwrap_or_else(|| self.snippet(e.span));
  93
  94             self.buffer.push_str(&rewrite);
  95             self.last_pos = e.span.hi;
  96
  97             if utils::semicolon_for_expr(e) {
  98                 self.buffer.push_str(";");
  99             }
 100         }
 101
 102         // FIXME: we should compress any newlines here to just one
 103         self.format_missing_with_indent(b.span.hi - brace_compensation);
 104         self.close_block();
 105         self.last_pos = b.span.hi;
 106     }
 107
 108     // FIXME: this is a terrible hack to indent the comments between the last
 109     // item in the block and the closing brace to the block's level.
 110     // The closing brace itself, however, should be indented at a shallower
 111     // level.
 112     fn close_block(&mut self) {
 113         let total_len = self.buffer.len;
 114         let chars_too_many = if self.config.hard_tabs {
 115             1
 116         } else {
 117             self.config.tab_spaces
 118         };
 119         self.buffer.truncate(total_len - chars_too_many);
 120         self.buffer.push_str("}");
 121         self.block_indent = self.block_indent.block_unindent(self.config);
 122     }
 123
 124     // Note that this only gets called for function definitions. Required methods
 125     // on traits do not get handled here.
 126     fn visit_fn(&mut self,
 127                 fk: visit::FnKind,
 128                 fd: &ast::FnDecl,
 129                 b: &ast::Block,
 130                 s: Span,
 131                 _: ast::NodeId) {
 132         let indent = self.block_indent;
 133         let rewrite = match fk {
 134             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 135                 self.rewrite_fn(indent,
 136                                 ident,
 137                                 fd,
 138                                 None,
 139                                 generics,
 140                                 unsafety,
 141                                 constness,
 142                                 abi,
 143                                 vis,
 144                                 codemap::mk_sp(s.lo, b.span.lo),
 145                                 &b)
 146             }
 147             visit::FnKind::Method(ident, ref sig, vis) => {
 148                 self.rewrite_fn(indent,
 149                                 ident,
 150                                 fd,
 151                                 Some(&sig.explicit_self),
 152                                 &sig.generics,
 153                                 sig.unsafety,
 154                                 sig.constness,
 155                                 sig.abi,
 156                                 vis.unwrap_or(ast::Visibility::Inherited),
 157                                 codemap::mk_sp(s.lo, b.span.lo),
 158                                 &b)
 159             }
 160             visit::FnKind::Closure => None,
 161         };
 162
 163         if let Some(fn_str) = rewrite {
 164             self.format_missing_with_indent(s.lo);
 165             self.buffer.push_str(&fn_str);
 166             if let Some(c) = fn_str.chars().last() {
 167                 if c == '}' {
 168                     self.last_pos = b.span.hi;
 169                     return;
 170                 }
 171             }
 172         } else {
 173             self.format_missing(b.span.lo);
 174         }
 175
 176         self.last_pos = b.span.lo;
 177         self.visit_block(b)
 178     }
 179
 180     fn visit_item(&mut self, item: &ast::Item) {
 181         // Don't look at attributes for modules (except for rustfmt_skip).
 182         // We want to avoid looking at attributes in another file, which the AST
 183         // doesn't distinguish.
 184         // FIXME This is overly conservative and means we miss attributes on
 185         // inline modules.
 186         match item.node {
 187             ast::ItemKind::Mod(_) => {
 188                 if utils::contains_skip(&item.attrs) {
 189                     return;
 190                 }
 191             }
 192             _ => {
 193                 if self.visit_attrs(&item.attrs) {
 194                     self.push_rewrite(item.span, None);
 195                     return;
 196                 }
 197             }
 198         }
 199
 200         match item.node {
 201             ast::ItemKind::Use(ref vp) => {
 202                 self.format_import(item.vis, vp, item.span);
 203             }
 204             ast::ItemKind::Impl(..) => {
 205                 self.format_missing_with_indent(item.span.lo);
 206                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 207                     self.buffer.push_str(&impl_str);
 208                     self.last_pos = item.span.hi;
 209                 }
 210             }
 211             ast::ItemKind::Trait(..) => {
 212                 self.format_missing_with_indent(item.span.lo);
 213                 if let Some(trait_str) = format_trait(&self.get_context(),
 214                                                       item,
 215                                                       self.block_indent) {
 216                     self.buffer.push_str(&trait_str);
 217                     self.last_pos = item.span.hi;
 218                 }
 219             }
 220             ast::ItemKind::ExternCrate(_) => {
 221                 self.format_missing_with_indent(item.span.lo);
 222                 let new_str = self.snippet(item.span);
 223                 self.buffer.push_str(&new_str);
 224                 self.last_pos = item.span.hi;
 225             }
 226             ast::ItemKind::Struct(ref def, ref generics) => {
 227                 let rewrite = {
 228                     let indent = self.block_indent;
 229                     let context = self.get_context();
 230                     ::items::format_struct(&context,
 231                                            "struct ",
 232                                            item.ident,
 233                                            item.vis,
 234                                            def,
 235                                            Some(generics),
 236                                            item.span,
 237                                            indent)
 238                         .map(|s| {
 239                             match *def {
 240                                 ast::VariantData::Tuple(..) => s + ";",
 241                                 _ => s,
 242                             }
 243                         })
 244                 };
 245                 self.push_rewrite(item.span, rewrite);
 246             }
 247             ast::ItemKind::Enum(ref def, ref generics) => {
 248                 self.format_missing_with_indent(item.span.lo);
 249                 self.visit_enum(item.ident, item.vis, def, generics, item.span);
 250                 self.last_pos = item.span.hi;
 251             }
 252             ast::ItemKind::Mod(ref module) => {
 253                 self.format_missing_with_indent(item.span.lo);
 254                 self.format_mod(module, item.vis, item.span, item.ident);
 255             }
 256             ast::ItemKind::Mac(ref mac) => {
 257                 self.format_missing_with_indent(item.span.lo);
 258                 self.visit_mac(mac);
 259             }
 260             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 261                 self.format_missing_with_indent(item.span.lo);
 262                 self.format_foreign_mod(foreign_mod, item.span);
 263             }
 264             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 265                 let rewrite = rewrite_static("static",
 266                                              item.vis,
 267                                              item.ident,
 268                                              ty,
 269                                              mutability,
 270                                              expr,
 271                                              &self.get_context());
 272                 self.push_rewrite(item.span, rewrite);
 273             }
 274             ast::ItemKind::Const(ref ty, ref expr) => {
 275                 let rewrite = rewrite_static("const",
 276                                              item.vis,
 277                                              item.ident,
 278                                              ty,
 279                                              ast::Mutability::Immutable,
 280                                              expr,
 281                                              &self.get_context());
 282                 self.push_rewrite(item.span, rewrite);
 283             }
 284             ast::ItemKind::DefaultImpl(..) => {
 285                 // FIXME(#78): format impl definitions.
 286             }
 287             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 288                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 289                                                     generics,
 290                                                     unsafety,
 291                                                     constness,
 292                                                     abi,
 293                                                     item.vis),
 294                               decl,
 295                               body,
 296                               item.span,
 297                               item.id)
 298             }
 299             ast::ItemKind::Ty(ref ty, ref generics) => {
 300                 let rewrite = rewrite_type_alias(&self.get_context(),
 301                                                  self.block_indent,
 302                                                  item.ident,
 303                                                  ty,
 304                                                  generics,
 305                                                  item.vis,
 306                                                  item.span);
 307                 self.push_rewrite(item.span, rewrite);
 308             }
 309         }
 310     }
 311
 312     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 313         if self.visit_attrs(&ti.attrs) {
 314             return;
 315         }
 316
 317         match ti.node {
 318             ast::TraitItemKind::Const(ref ty, ref expr) => {
 319                 let rewrite = rewrite_associated_static("const",
 320                                                         ast::Visibility::Inherited,
 321                                                         ti.ident,
 322                                                         ty,
 323                                                         ast::Mutability::Immutable,
 324                                                         expr,
 325                                                         &self.get_context());
 326                 self.push_rewrite(ti.span, rewrite);
 327             }
 328             ast::TraitItemKind::Method(ref sig, None) => {
 329                 let indent = self.block_indent;
 330                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 331                 self.push_rewrite(ti.span, rewrite);
 332             }
 333             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 334                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 335                               &sig.decl,
 336                               &body,
 337                               ti.span,
 338                               ti.id);
 339             }
 340             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 341                 let rewrite = rewrite_associated_type("type",
 342                                                       ti.ident,
 343                                                       None,
 344                                                       Some(type_param_bounds),
 345                                                       &self.get_context(),
 346                                                       self.block_indent);
 347                 self.push_rewrite(ti.span, rewrite);
 348             }
 349         }
 350     }
 351
 352     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 353         if self.visit_attrs(&ii.attrs) {
 354             return;
 355         }
 356
 357         match ii.node {
 358             ast::ImplItemKind::Method(ref sig, ref body) => {
 359                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
 360                               &sig.decl,
 361                               body,
 362                               ii.span,
 363                               ii.id);
 364             }
 365             ast::ImplItemKind::Const(ref ty, ref expr) => {
 366                 let rewrite = rewrite_static("const",
 367                                              ast::Visibility::Inherited,
 368                                              ii.ident,
 369                                              ty,
 370                                              ast::Mutability::Immutable,
 371                                              &expr,
 372                                              &self.get_context());
 373                 self.push_rewrite(ii.span, rewrite);
 374             }
 375             ast::ImplItemKind::Type(ref ty) => {
 376                 let rewrite = rewrite_associated_type("type",
 377                                                       ii.ident,
 378                                                       Some(ty),
 379                                                       None,
 380                                                       &self.get_context(),
 381                                                       self.block_indent);
 382                 self.push_rewrite(ii.span, rewrite);
 383             }
 384             ast::ImplItemKind::Macro(ref mac) => {
 385                 self.format_missing_with_indent(ii.span.lo);
 386                 self.visit_mac(mac);
 387             }
 388         }
 389     }
 390
 391     fn visit_mac(&mut self, mac: &ast::Mac) {
 392         // 1 = ;
 393         let width = self.config.max_width - self.block_indent.width() - 1;
 394         let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
 395
 396         if let Some(res) = rewrite {
 397             self.buffer.push_str(&res);
 398             self.last_pos = mac.span.hi;
 399         }
 400     }
 401
 402     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 403         self.format_missing_with_indent(span.lo);
 404         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 405         self.buffer.push_str(&result);
 406         self.last_pos = span.hi;
 407     }
 408
 409     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 410         FmtVisitor {
 411             parse_session: parse_session,
 412             codemap: parse_session.codemap(),
 413             buffer: StringBuffer::new(),
 414             last_pos: BytePos(0),
 415             block_indent: Indent {
 416                 block_indent: 0,
 417                 alignment: 0,
 418             },
 419             config: config,
 420         }
 421     }
 422
 423     pub fn snippet(&self, span: Span) -> String {
 424         match self.codemap.span_to_snippet(span) {
 425             Ok(s) => s,
 426             Err(_) => {
 427                 println!("Couldn't make snippet for span {:?}->{:?}",
 428                          self.codemap.lookup_char_pos(span.lo),
 429                          self.codemap.lookup_char_pos(span.hi));
 430                 "".to_owned()
 431             }
 432         }
 433     }
 434
 435     // Returns true if we should skip the following item.
 436     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 437         if utils::contains_skip(attrs) {
 438             return true;
 439         }
 440
 441         let outers: Vec<_> = attrs.iter()
 442                                   .filter(|a| a.node.style == ast::AttrStyle::Outer)
 443                                   .cloned()
 444                                   .collect();
 445         if outers.is_empty() {
 446             return false;
 447         }
 448
 449         let first = &outers[0];
 450         self.format_missing_with_indent(first.span.lo);
 451
 452         let rewrite = outers.rewrite(&self.get_context(),
 453                                      self.config.max_width - self.block_indent.width(),
 454                                      self.block_indent)
 455                             .unwrap();
 456         self.buffer.push_str(&rewrite);
 457         let last = outers.last().unwrap();
 458         self.last_pos = last.span.hi;
 459         false
 460     }
 461
 462     fn walk_mod_items(&mut self, m: &ast::Mod) {
 463         for item in &m.items {
 464             self.visit_item(&item);
 465         }
 466     }
 467
 468     fn format_mod(&mut self, m: &ast::Mod, vis: ast::Visibility, s: Span, ident: ast::Ident) {
 469         // Decide whether this is an inline mod or an external mod.
 470         let local_file_name = self.codemap.span_to_filename(s);
 471         let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
 472
 473         self.buffer.push_str(utils::format_visibility(vis));
 474         self.buffer.push_str("mod ");
 475         self.buffer.push_str(&ident.to_string());
 476
 477         if is_internal {
 478             self.buffer.push_str(" {");
 479             // Hackery to account for the closing }.
 480             let mod_lo = ::utils::span_after(s, "{", self.codemap);
 481             let body_snippet = self.snippet(codemap::mk_sp(mod_lo, m.inner.hi - BytePos(1)));
 482             let body_snippet = body_snippet.trim();
 483             if body_snippet.is_empty() {
 484                 self.buffer.push_str("}");
 485             } else {
 486                 self.last_pos = mod_lo;
 487                 self.block_indent = self.block_indent.block_indent(self.config);
 488                 self.walk_mod_items(m);
 489                 self.format_missing_with_indent(m.inner.hi - BytePos(1));
 490                 self.close_block();
 491             }
 492             self.last_pos = m.inner.hi;
 493         } else {
 494             self.buffer.push_str(";");
 495             self.last_pos = s.hi;
 496         }
 497     }
 498
 499     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 500         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 501         self.last_pos = filemap.start_pos;
 502         self.block_indent = Indent::empty();
 503         self.walk_mod_items(m);
 504         self.format_missing(filemap.end_pos);
 505     }
 506
 507     fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
 508         let vis = utils::format_visibility(vis);
 509         let mut offset = self.block_indent;
 510         offset.alignment += vis.len() + "use ".len();
 511         // 1 = ";"
 512         match vp.rewrite(&self.get_context(),
 513                          self.config.max_width - offset.width() - 1,
 514                          offset) {
 515             Some(ref s) if s.is_empty() => {
 516                 // Format up to last newline
 517                 let prev_span = codemap::mk_sp(self.last_pos, span.lo);
 518                 let span_end = match self.snippet(prev_span).rfind('\n') {
 519                     Some(offset) => self.last_pos + BytePos(offset as u32),
 520                     None => span.lo,
 521                 };
 522                 self.format_missing(span_end);
 523                 self.last_pos = span.hi;
 524             }
 525             Some(ref s) => {
 526                 let s = format!("{}use {};", vis, s);
 527                 self.format_missing_with_indent(span.lo);
 528                 self.buffer.push_str(&s);
 529                 self.last_pos = span.hi;
 530             }
 531             None => {
 532                 self.format_missing_with_indent(span.lo);
 533                 self.format_missing(span.hi);
 534             }
 535         }
 536     }
 537
 538     pub fn get_context(&self) -> RewriteContext {
 539         RewriteContext {
 540             parse_session: self.parse_session,
 541             codemap: self.codemap,
 542             config: self.config,
 543             block_indent: self.block_indent,
 544         }
 545     }
 546 }
 547
 548 impl<'a> Rewrite for [ast::Attribute] {
 549     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 550         let mut result = String::new();
 551         if self.is_empty() {
 552             return Some(result);
 553         }
 554         let indent = offset.to_string(context.config);
 555
 556         for (i, a) in self.iter().enumerate() {
 557             let a_str = context.snippet(a.span);
 558
 559             // Write comments and blank lines between attributes.
 560             if i > 0 {
 561                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 562                 // This particular horror show is to preserve line breaks in between doc
 563                 // comments. An alternative would be to force such line breaks to start
 564                 // with the usual doc comment token.
 565                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 566                 let comment = comment.trim();
 567                 if !comment.is_empty() {
 568                     let comment = try_opt!(rewrite_comment(comment,
 569                                                            false,
 570                                                            context.config.max_width -
 571                                                            offset.width(),
 572                                                            offset,
 573                                                            context.config));
 574                     result.push_str(&indent);
 575                     result.push_str(&comment);
 576                     result.push('\n');
 577                 } else if multi_line {
 578                     result.push('\n');
 579                 }
 580                 result.push_str(&indent);
 581             }
 582
 583             // Write the attribute itself.
 584             result.push_str(&a_str);
 585
 586             if i < self.len() - 1 {
 587                 result.push('\n');
 588             }
 589         }
 590
 591         Some(result)
 592     }
 593 }